Power conversion apparatus

A power conversion apparatus includes a main circuit with switches, and performs power conversion to generate power to a three-phase AC load from a three- or single-phase AC power supply. Some of the switches are configured, using a bidirectional switch including a normally-on device that is turned OFF when a gate circuit is provided with a positive or negative voltage, and a normally-off device that is turned ON when the gate circuit is provided with a positive or negative voltage, to provide only a specific unidirectional current flow when the gate circuit is not activated, and when the gate circuit is activated, provide and control a bidirectional current flow to direct only in an arbitrary unidirectional way. By providing the power conversion apparatus with a capability of directing back, to a load (motor), any power coming therefrom, the conversion apparatus requires no direct-current link capacitor and a diode clamping circuit.

TECHNICAL FIELD

The present invention relates to a power conversion apparatus and, more particularly, to a power conversion apparatus configured by a plurality of switches being high in power density or capable of realizing a power integrated circuit.

BACKGROUND ART

The power consumption of motors has been increased in homes, industries, and transportation systems, for example, and reducing such a power consumption of motors is important considering the recent energy-saving-oriented society and the continuous increase of electric energy availability. For optimizing the energy for use in a motor, the motor is controlled in terms of output rotation speed using an AC-to-AC power conversion apparatus. The issue here is that, however, such a power conversion apparatus for use with a motor is hardly popular in the current market, and is expected to be more popular and widely used from this time forward. In order to encourage the use of the power conversion apparatus, there needs to achieve reduction of material by increasing the power density in the power conversion apparatus, and there also needs to implement a general-purpose power integrated circuit by designing the power conversion apparatus with a highly integrated design.

FIGS. 1 to 3are each a circuit diagram of a conventional power conversion apparatus that performs power conversion into an AC load from an AC power supply via a DC section. Specifically,FIG. 1shows an apparatus that performs power conversion into a three-phase AC load from a three-phase AC power supply via a three-phase full-bridge circuit1, a DC link capacitor2, and a three-phase full-bridge circuit3.FIG. 2shows an apparatus that performs power conversion into a three-phase AC load from a single-phase AC power supply via a single-phase full-bridge circuit4, the DC link capacitor2, and a three-phase full-bridge circuit5.FIG. 3shows an apparatus that performs power conversion into a three-phase AC load from a single-phase AC power supply via a single-phase full-bridge circuit6, a composite chopper circuit7, the DC link capacitor2, and a three-phase full-bridge circuit8.

FIGS. 4 to 7are each a circuit diagram of a conventional power conversion apparatus that performs power conversion into an AC load from an AC power supply not via a DC section but directly. Specifically,FIG. 4shows a direct power conversion apparatus of an indirect type, i.e., indirect matrix converter, that performs power conversion into a three-phase AC load from a three-phase AC power supply via two three-phase full-bridge circuits9and10.FIG. 5shows another direct power conversion apparatus of an indirect type, i.e., indirect matrix converter, that performs power conversion into a three-phase AC load from a single-phase AC power supply via a single-phase full-bridge circuit12and a three-phase full-bridge circuit13.FIG. 6shows an apparatus that performs power conversion into a three-phase AC load from a three-phase AC power supply via a direct power conversion circuit of a direct type, i.e., direct matrix converter,14.FIG. 7shows an apparatus that performs power conversion into a three-phase AC load from a single-phase AC power supply via a direct power conversion circuit of a direct type, i.e., direct matrix converter,15.

FIGS. 8 to 13each show a bidirectional switch for use in the power conversion apparatus described above for direct conversion from AC to AC. Specifically,FIG. 8shows a bidirectional switch configured by a thyristor or a Gate Turn-Off thyristor (GTO) connected in reverse parallel with another.FIG. 9shows a bidirectional switch configured by a diode bridge circuit connected with an Insulated Gate Bipolar Transistor (IGBT).FIG. 10shows a bidirectional switch including an IGBT connected in reverse parallel with a diode, and the connecting structure is connected with another to face each other with the emitter side in shared use.FIG. 11shows a bidirectional switch including an IGBT connected in reverse parallel with a diode, and the connecting structure is connected with another to face each other with the collector side in shared use.FIG. 12shows a bidirectional switch including an IGBT connected in series with a diode, and the connecting structure is connected in reverse parallel with another. InFIG. 12example, alternatively, the drift layer of the diode connected in series with the IGBT may be shared for use with another, and the resulting element piece, i.e., the reverse-blocking IGBT, may be connected in reverse parallel with another.FIG. 13shows a bidirectional switch including a MOSFET connected with another to face each other with the source side in shared use.

In all the bidirectional switches ofFIGS. 8 to 13, when any of a gate power supply, a control power supply, and a gate circuit is not activated, current flow is cut off bidirectionally.

The power conversion apparatuses ofFIGS. 1 to 7are each used as a power supply mainly for driving a motor. When the motor is driven thereby, the flow of power is directed in two directions, i.e., one is from the power supply to the motor (powering operation), and the other is from the motor to the power supply (regenerative operation). When such a flow of power is abruptly changed, the need arises to process the power of delay caused by controlling and switching inside of the power conversion apparatus. In consideration thereof, the apparatuses ofFIGS. 1 to 3are each provided with the DC link capacitor2of a large capacity for power processing, and the apparatuses ofFIGS. 4 to 7are each connected with a diode clamping circuit11for power processing.

FIG. 14shows a specific example of the diode clamping circuit11for power conversion into a three-phase AC load from a three-phase AC power supply.FIG. 15shows a specific example of the diode clamping circuit11for power conversion into a three-phase AC load from a single-phase AC power supply. In the diode clamping circuit, a capacitor16is used. The power from the load or the power supply is stored in the capacitor16, and is discharged, as power loss, by a resistor17connected in parallel to the capacitor16.

The power conversion apparatuses ofFIGS. 4 to 7have been implemented by using a semiconductor device with which the bidirectional current flow is allowed. With a conventional bidirectional switch typified by those ofFIGS. 8 to 13, however, the flow of current cannot be controlled when a power failure occurs in the gate power supply, the control power supply, and the gate circuit. When the components in the power conversion apparatus, i.e., an input power supply, the gate power supply, the control power supply, and the gate circuit, suffer from sudden failures, momentary (short-time) power failures, and momentary voltage drop, or when a motor is with hard braking or is operated under light load, a diode clamping circuit is connected, and the DC link thereof is connected with a large-capacity capacitor and a discharge resistor, for processing the energy stored in the motor.

The problem here is that the DC link capacitor and the diode clamping circuit described above each occupy a large portion of volume of the power conversion apparatus, and this is the obstacle to achieve the high power density and highly integrated design of the power conversion apparatus.

DISCLOSURE OF INVENTION

Motors have been prevented from being energy saving because power conversion apparatuses for use to drive the motors are not yet high in power density or not yet designed with high integration. Especially motors of a low output capacity, i.e., equal to or lower than several kW, have been prevented from being energy saving.

In a power conversion apparatus for motor driving use, there is no room for the power to go when the motor is in the regenerative operation. As such, the power conversion apparatuses ofFIGS. 1 to 3, i.e., apparatuses of DC link type, all require a large-capacity DC link capacitor. However, such a DC link capacitor is generally high in required resistance to pressure and large in capacity, thereby becoming an obstacle to achieve the high power density and highly integrated design.

Among the power conversion apparatuses for motor driving use, the power conversion apparatuses ofFIGS. 4 to 7, those perform direct conversion from AC to AC do not include a DC link section and a large-capacity capacitor. Therefore, there needs to connect a diode clamping circuit on both input and output sides, and therebetween, to provide a circuit similar to a DC link capacitor. This configuration, however, prevents the high power density and highly integrated design because the capacitor provided in each of the diode clamping circuits is large in size, a resistor is required for discharging the energy stored in the capacitor, and a cooling apparatus is required due to heat generated via the resistor at the time of discharge of the energy.

For decreasing the power consumption of the motors making up the dominant portion of the entire amount, the power conversion apparatus being high in power density or highly integrated design has to be more popular and widely used. However, no technology is yet proposed to reduce the size of or eliminate the DC link capacitor and the diode clamping circuit, which occupy most of the volume of the power conversion apparatus.

Particularly, for reducing the size of or eliminating the DC link capacitor and the diode clamping circuit occupying most of the volume of the power conversion apparatus as such, any special design considerations are required not to store any regenerative power in the power conversion apparatus from a load such as motor, but no such technology is yet specifically proposed.

In the power conversion apparatuses ofFIGS. 4 to 7, i.e., apparatuses of direct conversion from AC to AC with no DC section involved, the diode clamping circuit may be indeed not required any more if any regenerative power from a load such as motor can be put back thereto by providing a path specifically therefor other than the diode clamping circuit. However, the bidirectional switches ofFIGS. 8 to 13do not serve well enough to put back the regenerative power from the motor to the switch sections ofFIGS. 4 to 7.

In consideration thereof, an object of the invention is to provide an AC-to-AC power conversion apparatus not including a DC link capacitor and a diode clamping circuit by providing a capability of directing back, to a load such as motor, any power coming therefrom when the flow of power is changed, i.e., when the load such as motor is changed from powering operation to regenerative operation, or when any of the components connected to a semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

In a power conversion apparatus of the invention, the main circuit includes a plurality of switches, and power conversion is performed to generate power for supply to an AC load from a three- or single-phase AC power supply. Using a bidirectional switch configured by a normally-on device and a normally-off device, at least some of the plurality of switches are configured to provide only a specific unidirectional current flow when a gate circuit is not activated, and when the gate circuit is activated, provide a bidirectional current flow and control the current flow to direct in an arbitrary unidirectional way. The normally-on device is the one that is turned OFF when the gate circuit is provided with either a positive or negative voltage, and the normally-off device is the one that is turned ON when the gate circuit is provided with either a positive or negative voltage. With such a configuration, without requiring a component element for storing the energy in the power conversion apparatus, the power from the load can be circulated between the power conversion apparatus and the load.

The bidirectional switches ofFIGS. 16 to 18are each a semiconductor device having capabilities of providing only a specific unidirectional current flow when the gate circuit including the gate power supply and the control power supply is not activated, and when such a gate circuit including the gate power supply and the control power supply is activated, providing a bidirectional current flow and controlling the current flow to direct in an arbitrary unidirectional way. By using such a semiconductor device in the AC-to-AC power conversion apparatus, the power conversion apparatus is provided with a capability of directing back, to a load such as motor, any power coming therefrom when the component connected to the semiconductor device is not activated, i.e., the gate circuit including the gate power supply and the control power supply.FIG. 16shows a three-terminal switch,FIG. 17shows a four-terminal switch, andFIG. 18shows a five-terminal switch. These three-, four-, and five-terminal switches are specifically shown inFIGS. 19 and 20,FIGS. 21 and 22, andFIGS. 23 and 24, respectively.

The bidirectional switches ofFIGS. 19 to 24are each a semiconductor device in which a switch section is a combination of a normally-on device and a normally-off device. The normally-on device is the one that is turned OFF when a gate circuit is provided with either a positive or negative voltage, and the normally-off device is the one that is turned ON when the gate circuit is provided with either a positive or negative voltage. The bidirectional switches ofFIGS. 19 to 24are all capable of controlling a current flow to direct in an arbitrary unidirectional way only in response to an input signal coming from the gate circuit. When the gate circuit is not activated, a diode connected in parallel to the normally-off device forms a current path with the normally-on device, thereby being able to direct the current flow in a specific unidirectional way only. Specifically, the bidirectional switches ofFIGS. 23 and 24are each provided with a drain terminal between the normally-on device and the normally-off device, and this configuration allows a first or second source and the drain terminal to provide a bidirectional current flow when the gate circuit is not activated, or allows the first or second source and the drain terminal to provide only a specific unidirectional current flow. As such, the power conversion apparatus is provided with a capability of directing back, to a load such as motor, any power coming therefrom when the flow of current s changed, i.e., when the motor is changed from powering operation to regenerative operation, or when any of the components connected to the semiconductor device is not activated, i.e., the gate power supply, the control power supply, and the gate circuit.

With the AC-to-AC power conversion apparatus implemented as such without requiring a DC link capacitor and a diode clamping circuit, the resulting power conversion apparatus being high in power density or implementing a power integrated circuit is expected to be widely used specifically for motor driving use.

In order to solve the problems described above and achieve the object described above, an aspect of the invention is directed to a power conversion apparatus or a power integrated circuit that can deal with the flow of current from a motor in any case without requiring a DC link capacitor and a diode clamping circuit, e.g., when the flow of current is changed, i.e., when a motor is changed from powering operation to regenerative operation, when any of components connected to a semiconductor device is not activated, i.e., the gate circuit including the gate power supply and the control power supply, when an input power supply in the power conversion apparatus suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load. Such a power conversion apparatus or a power integrated circuit can be provided using the semiconductor devices ofFIGS. 16 to 18, each having a capability of providing only a specific unidirectional current flow when the gate circuit including the gate power supply and the control power supply is not activated, and when the gate circuit including the gate power supply and the control power supply is activated, providing a bidirectional current flow and controlling the current flow to direct only in an arbitrary unidirectional way.

Another aspect of the invention is directed to a power conversion apparatus or a power integrated circuit that performs power conversion into a three-phase AC from a three- or single-phase AC without including the DC link capacitor and the diode clamping circuit described above.

The invention implements a power conversion apparatus or a power integrated circuit that performs power conversion into a three-phase AC from a three- or single-phase AC, and the resulting power conversion apparatus can be used for motor driving use at low cost, thereby contributing to good energy efficiency of motors.

The invention implements a power conversion apparatus or a power integrated circuit being high in power density that performs power conversion into a three-phase AC from a single-phase AC. The invention provides the good energy efficiency of motors driven by a single-phase AC power supply especially for use in household appliances such as air conditioners, refrigerators, washing machines, and vacuum cleaners.

In a conventional power conversion apparatus, when the input power supply therein suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, a diode clamping circuit has been working to absorb the power so that the component elements have been protected from damage. On the other hand, in the AC direct power conversion apparatus of the invention, using a bidirectional switch of the invention favorably eliminates any abrupt change of power and current, thereby being able to protect component elements without using a diode clamping circuit.

PREFERRED EMBODIMENTS OF THE INVENTION

In the below, any load to be driven by a power conversion apparatus of the invention is denoted as a three-phase AC load. The three-phase AC load includes an inductive load and a resistive load, which are operated by a three-phase alternating current such as brushless DC motor, induction motor, and synchronous motor. Such a three-phase AC load is surely not the only application option, but the invention is applicable to any other types of AC load such as single-phase AC load.

First Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 25shows a power conversion apparatus of the invention that drives a three-phase AC load from a three-phase AC power supply. To the side of the three-phase AC power supply, a filter section is connected. The filter section is configured by an inductor or a capacitor. An AC-to-AC conversion circuit section is provided with switches, which are partially or entirely any of the bidirectional switches ofFIGS. 16 to 18or a combination thereof, thereby implementing the power conversion apparatus not requiring a DC link capacitor and a diode clamping circuit.

The AC-to-AC conversion circuit section ofFIG. 25is so configured as to perform power conversion without via a DC circuit and any component for storage of energy. Such an AC-to-AC conversion circuit section uses an AC direct power conversion circuit of an indirect type (matrix converter; refer toFIG. 4), or a direct power conversion circuit of a direct type (direct-type matrix converter; refer toFIG. 6). The indirect-type AC power conversion circuit is in the configuration that a three-phase full-bridge circuit on the power-supply side is connected with a three-phase full-bridge circuit on the load side. In the direct-type power conversion circuit, nine bidirectional switches are connected to input/output lines between a three-phase AC power supply and a three-phase AC load.

FIG. 26shows another power conversion apparatus of the invention that drives a three-phase AC load from a single-phase AC power supply. To the side of the single-phase AC power supply, a filter section is connected. The filter section is configured by an inductor or a capacitor. An AC-to-AC conversion circuit section is provided with switches, which are partially or entirely any of the bidirectional switches ofFIGS. 16 to 18or a combination thereof, thereby implementing the power conversion apparatus not requiring a DC link capacitor and a diode clamping circuit.

The AC-to-AC conversion circuit section ofFIG. 26is so configured as to perform power conversion without via a DC circuit and any component element for storage of energy. Such an AC-to-AC conversion circuit section uses a direct power conversion circuit of an indirect (matrix converter; refer toFIG. 5), or a direct power conversion circuit of a direct type (direct-type matrix converter; refer toFIG. 7). The indirect-type power conversion circuit is in an AC indirect conversion circuit in which a single-phase full-bridge circuit on the power-supply side is connected with a three-phase full-bridge circuit on the load side. In the direct power conversion circuit, six bidirectional switches are connected to input/output lines between the single-phase AC power supply and the three-phase AC load.

FIGS. 19 and 20each show a bidirectional switch, i.e., three-terminal semiconductor device, configured by a normally on device18, a normally-off device19, and diodes20and21. The normally-on device18is turned OFF when a gate is provided with either a positive or negative voltage, and the normally-off device19is turned ON when the gate is provided with either a positive or negative voltage. The diodes20and21are connected in parallel to the normally-on and normally-off devices18and19, respectively. Such a bidirectional switch serves to provide only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switch is provided with a gate section, and two current paths, i.e., first and second sources. The bidirectional switch has a capability of controlling a current flow to the first and second sources in the two, at the maximum, operation modes depending on the signal combination provided to the gate section.

FIGS. 21 and 22each show a bidirectional switch, i.e., four-terminal semiconductor device, configured by the normally-on device18, the normally-off device19, and the diodes20and21. The normally-on device18is turned OFF when a gate is provided with either a positive or negative voltage, and the normally-off device19is turned ON when the gate is provided with either a positive or negative voltage. The diodes20and21are connected in parallel to the normally-on and normally-off devices18and19, respectively. Such a bidirectional switch serves to provide only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switch is provided with two gate sections, i.e., first and second gates, and two current paths, i.e., first and second sources. The bidirectional switch has a capability of controlling a current flow to the first and second sources in the four, at the maximum, operation modes depending on the signal combination provided to each of the gate sections.

FIGS. 23 and 24each show a bidirectional switch, i.e., five-terminal semiconductor device, configured by the normally-on device18, the normally-off device19, and the diodes20and21. The normally-on device18is turned OFF when a gate is provided with either a positive or negative voltage, and the normally-off device19is turned ON when the gate is provided with either a positive or negative voltage. The diodes20and21are connected in parallel to the normally-on and normally-off devices18and19, respectively. Such a bidirectional switch serves to provide only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switch is provided with two gate sections, i.e., first and second gates, and three current paths, i.e., first and second sources, and a drain. The bidirectional switch has a capability of controlling a current flow to the first and second sources in the four, at the maximum, operation modes depending on the signal combination provided to each of the gate sections. The drain terminal is provided between the normally-on device18and the normally-off device19so that another current flow is provided while a current flow to the first and second sources is being controlled.

FIGS. 27 to 32each show a circuit symbol of a bidirectional switch, i.e., semiconductor device, that provides only a specific unidirectional current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

Specifically,FIGS. 27 and 28each show a circuit symbol of a three-terminal bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device ofFIG. 16, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 27shows a circuit symbol of a semiconductor device that provides a unidirectional current flow from the second source to the first source when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 28shows a circuit symbol of a semiconductor device that provides a unidirectional current flow from the first source to the second source when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIGS. 29 and 30each show a circuit symbol of a four-terminal bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device ofFIG. 17, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 29shows a circuit symbol of a semiconductor device that provides a unidirectional current flow from the second source to the first source when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 30shows a circuit symbol of a semiconductor device that provides a unidirectional current flow from the first source to the second source when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIGS. 31 and 32each show a circuit symbol of a five-terminal bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device ofFIG. 18, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 31shows a circuit symbol of a semiconductor device that provides a unidirectional current flow only from the second source to the first source when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 32shows a circuit symbol of a semiconductor device that provides a unidirectional current flow only from the first source to the second source when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIGS. 33 to 51each show a specific example of a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIGS. 33 and 34each show a semiconductor device configured by a first n-type MOSFET section22, and a second n-type MOSFET section23. The first n-type MOSFET section22provides a unidirectional current flow only from a first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second n-type MOSFET section23provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 33shows a four-terminal semiconductor device, including two gate sections, i.e., first and second gates, and two current paths, i.e., first and second sources.FIG. 34shows a five-terminal semiconductor device, including two gate sections, i.e., first and second gates, and three current paths, i.e., first and second sources, and a drain.

The first and second n-type MOSFET sections are each provided therein with a diode. The first n-type MOSFET sections ofFIGS. 33 and 34correspond to the components ofFIGS. 19,21, and23, i.e., the normally-off device sections and the diode sections connected in parallel thereto, and the second n-type MOSFET sections correspond to the components ofFIGS. 19,21, and23, i.e., the normally-on device sections and the diode sections connected in parallel thereto.

FIG. 35shows a four-terminal semiconductor device of a lateral type configured by a first n-type MOSFET section24, and a second n-type MOSFET section25. The first n-type MOSFET section24provides a unidirectional current flow only from a first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second n-type MOSFET section25provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 36shows a four-terminal semiconductor device of a vertical type configured by a first n-type MOSFET section26, and a second n-type MOSFET section27. The first n-type MOSFET section26provides a unidirectional current flow only from a first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second n-type MOSFET section27provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The first n-type MOSFET section26is separated from the second n-type MOSFET section27by an insulator28.

FIG. 37shows a five-terminal semiconductor device of a lateral type configured by a first n-type MOSFET section29, and a second n-type MOSFET section30. The first n-type MOSFET section29provides a unidirectional current flow only from a first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second n-type MOSFET section30provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Between the first and second n-type MOSFET sections29and30, a drain terminal31is disposed.

FIG. 38shows a five-terminal semiconductor device of a lateral type configured by a first n-type MOSFET section32, and a second n-type MOSFET section33. The first n-type MOSFET section32provides a unidirectional current flow only from a first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second n-type MOSFET section33provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Between the first and second n-type MOSFET sections32and33, a drain terminal34is disposed. Moreover, the first n-type MOSFET section32is separated from the second n-type MOSFET section33by an insulator35.

FIG. 39shows a five-terminal semiconductor device of a vertical type configured by a first n-type MOSFET section36, and a second n-type MOSFET section37. The first n-type MOSFET section36provides a unidirectional current flow only from a first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second n-type MOSFET section37provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Between the first and second n-type MOSFET sections36and37, a drain terminal38is disposed. Moreover, the first n-type MOSFET section36is separated from the second n-type MOSFET section37by an insulator39.

In the semiconductor devices ofFIGS. 35 to 39, the first and second n-type MOSFET sections are each provided therein with a parasitic diode, or alternatively, are each externally connected with a diode.

With the semiconductor devices ofFIGS. 33 to 39, the first n-type MOSFET section is allowed to open the n-channel through application of a positive voltage to the first gate with respect to the first source, thereby being able to provide a bidirectional current flow. Through application of a negative voltage to the second gate with respect to the second source, the second n-type MOSFET section is allowed to close the n-channel, thereby being able to provide a unidirectional current flow only from the second source.

If voltage application is not performed to both the first and second gates, a unidirectional current flow is allowed only from the first source to the second source. When a positive voltage is applied to the first gate with respect to the first source to open the n-channel in the first n-type MOSFET section, and when no voltage is applied to the second gate, a bidirectional current flow is allowed, i.e., from the first source to the second source, and from the second source to the first source. When no voltage is applied to the first gate, and when a negative voltage is applied to the second gate with respect to the second source to close the n-channel in the second n-type MOSFET section, a current flow is cut off bidirectionally in the semiconductor device. When a positive voltage is applied to the first gate with respect to the first source to open the n-channel in the first n-type MOSFET section, and when a negative voltage is applied to the second gate with respect to the second source to close the n-channel in the second n-type MOSFET section, a unidirectional current flow is allowed only from the second source to the first source.

FIGS. 40 and 41each show a semiconductor device of a lateral type configured by a first p-type MOSFET section40, and a second p-type MOSFET section41. The first p-type MOSFET section40provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second p-type MOSFET section41provides a unidirectional current flow directing only to the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.FIG. 40shows a four-terminal semiconductor device, including two gate sections, i.e., first and second gates, and two current paths, i.e., first and second sources.FIG. 41shows a five-terminal semiconductor device, including two gate sections, i.e., first and second gates, and three current paths, i.e., first and second sources, and a drain.

The first and second p-type MOSFET sections are each provided therein with a diode. The first p-type MOSFET sections ofFIGS. 40 and 41correspond to the components ofFIGS. 20,22, and24, i.e., the normally-on device sections and the diode sections connected in parallel thereto, and the second p-type MOSFET sections correspond to the components ofFIGS. 20,22, and24, i.e., the normally-off device sections and the diode sections connected in parallel thereto.

FIG. 42shows a semiconductor device of a lateral type configured by a first p-type MOSFET section42, and a second p-type MOSFET section43. The first p-type MOSFET section42provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second p-type MOSFET section43provides a unidirectional current flow directing only to the second source when the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 43shows a semiconductor device of a vertical type configured by a first p-type MOSFET section44, and a second p-type MOSFET section45. The first p-type MOSFET section44provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second p-type MOSFET section45provides a unidirectional current flow directing only to the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The first p-type MOSFET section44is separated from the second p-type MOSFET section45by an insulator46.

FIG. 44shows a semiconductor device of a lateral type configured by a first p-type MOSFET section47, and a second p-type MOSFET section48. The first p-type MOSFET section47provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second p-type MOSFET section48provides a unidirectional current flow directing only to the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Between the first and second p-type MOSFET sections47and48, a drain terminal49is disposed.

FIG. 45shows a semiconductor device of a lateral type configured by a first p-type MOSFET section50, and a second p-type MOSFET section51. The first p-type MOSFET section50provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second p-type MOSFET section51provides a unidirectional current flow directing only to the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Between the first and second p-type MOSFET sections50and51, a drain terminal52is disposed. Moreover, the first p-type MOSFET section50is separated from the second p-type MOSFET section51by an insulator53.

FIG. 46shows a semiconductor device of a vertical type configured by a first p-type MOSFET section54, and a second p-type MOSFET section55. The first p-type MOSFET section54provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second p-type MOSFET section55provides a unidirectional current flow directing only to the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Between the first and second p-type MOSFET sections54and55, a drain terminal56is disposed. Moreover, the first p-type MOSFET section54is separated from the second p-type MOSFET section55by an insulator57.

In the semiconductor devices ofFIGS. 42 to 46, the first and second p-type MOSFET sections are each provided therein with a parasitic diode, or alternatively, are each externally connected with a diode.

With the semiconductor devices ofFIGS. 40 to 46, the first p-type MOSFET section is allowed to close the p-channel through application of a positive voltage to the first gate with respect to the first source, thereby being able to provide a unidirectional current flow only to the first source. Through application of a negative voltage to the second gate with respect to the second source, the second p-type MOSFET section is allowed to open the p-channel, thereby being able to provide a bidirectional current flow.

If voltage application is not performed to both the first and second gates, a current flow is allowed to direct only in unidirectional from the first source to the second source. When a positive voltage is applied to the first gate with respect to the first source to close the p-channel in the first p-type MOSFET section, and when no voltage is applied to the second gate, a current flow is cut off bidirectionally in the semiconductor device. When no voltage is applied to the first gate, and when a negative voltage is applied to the second gate with respect to the second source to open the p-channel in the second p-type MOSFET section, a bidirectional current flow is allowed from the first source to the second source, and from the second source to the first source. When a positive voltage is applied to the first gate with respect to the first source to close the p-channel in the first p-type MOSFET section, and when a negative voltage is applied to the second gate with respect to the second source to open the p-channel in the second p-type MOSFET section, a unidirectional current flow is allowed only from the second source to the first source.

FIG. 47shows a lateral-type semiconductor device of the super junction structure, i.e., a combination of two semiconductor devices. One semiconductor device is the one configured by a first n-type MOSFET section58, and a second n-type MOSFET section59. The first n-type MOSFET section58provides a unidirectional current flow only from the first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second n-type MOSFET section59provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The other semiconductor device is the one configured by a first p-type MOSFET section60, and a second p-type MOSFET section61. The first p-type MOSFET section60provides a unidirectional current flow only from the first source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second p-type MOSFET section61provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

In the semiconductor device ofFIG. 47, the first and second n-type MOSFET sections, and the first and second p-type MOSFET sections are each provided therein with a parasitic diode, or alternatively, are each externally connected with a diode.

With the semiconductor device ofFIG. 47, the first n-type MOSFET section is allowed to open the n-channel through application of a positive voltage to the first gate with respect to the first source, thereby being able to provide a bidirectional current flow. Through application of a negative voltage to the second gate with respect to the second source, the second p-type MOSFET section is allowed to open the p-channel, thereby being able to provide a bidirectional current flow.

If voltage application is not performed to both the first and second gates, a unidirectional current flow is allowed only from the first source to the second source. When a positive voltage is applied to the first gate with respect to the first source to open the n-channel in the first n-type MOSFET section, and when no voltage is applied to the second gate, a bidirectional current flow is allowed from the first source to the second source, and from the second source to the first source. When no voltage is applied to the first gate, and when a negative voltage is applied to the second gate with respect to the second source to open the p-channel in the second p-type MOSFET section, a bidirectional current flow is allowed from the first source to the second source, and from the second source to the first source. When a positive voltage is applied to the first gate with respect to the first source to open the n-channel in the first n-type MOSFET section and to close the p-channel in the first p-type MOSFET section, and when a negative voltage is applied to the second gate with respect to the second source to close the n-channel in the second n-type MOSFET section and to open the p-channel in the second p-type MOSFET section, a unidirectional current flow is allowed only from the second source to the first source.

FIG. 48shows a semiconductor device configured by a JFET (Junction FET) section62, a diode section63, and an n-type MOSFET section64. The JFET section62serves to provide a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The n-type MOSFET section64serves to provide a unidirectional current flow only from the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

In the semiconductor device ofFIG. 48, the JFET section and the n-type MOSFET section are each provided therein with a parasitic diode, or alternatively, are each externally connected with a diode.

Especially when the components, i.e., JFET, MOSFET, and diode, are made of silicon carbide, the performance can be favorably improved.

With the semiconductor device ofFIG. 48, the JFET section is allowed to close the n-channel through application of a negative voltage to the first gate with respect to the first source, thereby being able to cut off a bidirectional current flow. Through application of a positive voltage to the second gate with respect to the second source, the n-type MOSFET section is allowed to open the n-channel, thereby being able to provide a bidirectional current flow.

The JFET section ofFIG. 48corresponds to the normally-on device sections ofFIGS. 19,21, and23, and the diode connected in parallel to the JFET section corresponds to the diodes connected in parallel to the normally-on device sections ofFIGS. 19,21, and23. The n-type MOSFET section is provided therein with a diode, and the n-type MOSFET section ofFIG. 48corresponds to the components ofFIGS. 19,21, and23, i.e., the normally-off device sections and the diode sections connected in parallel thereto.

If voltage application is not performed to both the first and second gates, a unidirectional current flow is allowed only from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the JFET section, and when no voltage is applied to the second gate, a current flow is cut off bidirectionally. When no voltage is applied to the first gate, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the n-type MOSFET section, a bidirectional current flow is allowed from the first source to the second source, and from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the JFET section, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the n-type MOSFET section, a unidirectional current flow is allowed only from the first source to the second source.

FIG. 49shows a semiconductor device configured by a first JFET section65, a diode section66, a second JFET section67, and a diode section68. The first JFET section65serves to provide a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second JFET section67serves to provide a unidirectional current flow only from the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

The first JFET section ofFIG. 49corresponds to the normally-on device sections ofFIGS. 19,21, and23, and the diode connected in parallel to the first JFET section corresponds to the diodes connected in parallel to the normally-on device sections ofFIGS. 19,21, and23. The second JFET section corresponds to the normally-off device sections ofFIGS. 19,21, and23, and the diode connected in parallel to the second JFET section corresponds to the diode sections connected in parallel to the normally-off device sections ofFIGS. 19,21, and23.

In the semiconductor device ofFIG. 49, the first and second JFET sections are each provided therein with a parasitic diode, or alternatively, are each externally connected with a diode.

Especially when the components, i.e., JFET, and diode, are made of silicon carbide, the performance can be favorably improved.

With the semiconductor device ofFIG. 49, the first JFET section is allowed to close the n-channel through application of a negative voltage to the first gate with respect to the first source, thereby being able to cut off a current flow bidirectionally. Through application of a positive voltage to the second gate with respect to the second source, the second JFET section is allowed to open the n-channel, thereby being able to provide a bidirectional current flow.

If voltage application is not performed to both the first and second gates, a unidirectional current flow is allowed only from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the first JFET section, and when no voltage is applied to the second gate, a current flow is cut off bidirectionally. When no voltage is applied to the first gate, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the second JFET section, a bidirectional current flow is allowed from the first source to the second source, and from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the first JFET section, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the second JFET section, a unidirectional current flow is allowed only from the first source to the second source.

FIG. 50shows a semiconductor device configured by a MESFET (Metal Semiconductor FET) section69, a diode section70, and an n-type MOSFET section71. The MESFET section69provides a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The n-type MOSFET section71provides a unidirectional current flow only from the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

The MESFET section ofFIG. 50corresponds to the normally-on device sections ofFIGS. 19,21, and23, and the diode section connected in parallel to the MESFET section corresponds to the components ofFIGS. 19,21, and23, i.e., the diode sections connected in parallel to the normally-on device sections. The n-type MOSFET section is provided therein with a diode, and the n-type MOSFET section ofFIG. 50corresponds to the components ofFIGS. 19,21, and23, i.e., the normally-on device sections and the diode sections connected in parallel thereto.

In the semiconductor device ofFIG. 50, the MESFET section and the n-type MOSFET section are each provided therein with a parasitic diode, or alternatively, are each externally connected with a diode.

Especially when the component, i.e., MESFET, diode, or MOSFET, is made of gallium nitride, the performance can be favorably improved.

With the semiconductor device ofFIG. 50, the MESFET section is allowed to close the n-channel through application of a negative voltage to the first gate with respect to the first source, thereby cutting off a current flow bidirectionally. Through application of a positive voltage to the second gate with respect to the second source, the n-type MOSFET section is allowed to open the n-channel, thereby being able to provide a bidirectional current flow.

If voltage application is not performed to both the first and second gates, a unidirectional current flow is allowed only from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the MESFET section, and when no voltage is applied to the second gate, a current flow is cut off bidirectionally. When no voltage is applied to the first gate, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the n-type MOSFET section, a bidirectional current flow is allowed from the first source to the second source, and from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the MESFET section, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the n-type MOSFET section, a unidirectional current flow is allowed only from the first source to the second source.

FIG. 51shows a semiconductor device configured by a first MESFET section72, a diode section73, a second MESFET section74, and a diode section75. The first MESFET section72serves to provide a bidirectional current flow when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The second MESFET section74provides a unidirectional current flow only from the second source when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

The first MESFET section ofFIG. 51corresponds to the normally-on device sections ofFIGS. 19,21, and23, and the diode connected in parallel to the first MESFET section corresponds to the diodes connected in parallel to the normally-on device sections ofFIGS. 19,21, and23. The second MESFET section corresponds to the normally-off device sections ofFIGS. 19,21, and23, and the diode section connected in parallel to the second MESFET section corresponds to the diode sections connected in parallel to the normally-off device sections ofFIGS. 19,21, and23.

In the semiconductor device ofFIG. 51, the first and second MESFET sections are each provided therein with a parasitic diode, or alternatively, are each externally connected with a diode.

Especially when the components, i.e., MESFET, and diode, are made of gallium nitride, the performance can be favorably improved.

With the semiconductor device ofFIG. 51, the first MESFET section is allowed to close the n-channel through application of a negative voltage to the first gate with respect to the first source, thereby cutting off a current flow bidirectionally. Through application of a positive voltage to the second gate with respect to the second source, the second MESFET section is allowed to open the n channel, thereby being able to provide a bidirectional current flow.

If voltage application is not performed to both the first and second gates, a unidirectional current flow is allowed only from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the MESFET section, and when no voltage is applied to the second gate, a current flow is cut off bidirectionally. When no voltage is applied to the first gate, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the second MESFET section, a bidirectional current flow is allowed from the first source to the second source, and from the second source to the first source. When a negative voltage is applied to the first gate with respect to the first source to close the n-channel in the first MESFET section, and when a positive voltage is applied to the second gate with respect to the second source to open the n-channel in the second MESFET section, a unidirectional current flow is allowed only from the first source to the second source.

Second Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 52shows a power conversion apparatus of the invention that drives a three-phase AC load from a three-phase AC power supply. The side of the three-phase AC power supply is connected with a filter76, which is configured by an inductor and a capacitor. In a three-phase full-bridge circuit77on the side of the three-phase AC power supply, second switch sections provided in two legs are each a bidirectional switch that cuts off a current flow when any of components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Note here that the leg denotes a circuit constituting an AC phase in the power conversion apparatus, or a circuit inserted in parallel thereinto. The bidirectional switches ofFIGS. 8 to 13are each a specific example thereof, and any of or a combination of these bidirectional switches is used. In the three-phase full-bridge circuit77on the side of the three-phase AC power supply, first switch sections provided in one leg are each a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. This is applicable also to first switch sections provided in every leg in a three-phase full-bridge circuit78on the side of the three-phase AC load. Such bidirectional switches are each any of or a combination of the bidirectional switches ofFIGS. 16 to 18. With such a configuration, the resulting power conversion apparatus does not require a DC link capacitor and a diode clamping circuit.

FIG. 53shows a power conversion apparatus similar to that ofFIG. 52but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply, and the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 54shows a power conversion apparatus similar to that ofFIG. 52but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply, and the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 55shows a power conversion apparatus similar to that ofFIG. 52but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by a MOSFET and a diode ofFIG. 56. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 57shows a power conversion apparatus similar to that ofFIG. 52but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by an IGBT and a diode ofFIG. 58. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

Third Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 59shows a power conversion apparatus of the invention that drives a three-phase AC load from a single-phase AC power supply. The side of the single-phase AC power supply is connected with a filter79, which is configured by an inductor and a capacitor. In a single-phase full-bridge circuit80on the side of the single-phase AC power supply ofFIG. 59, second switch sections provided in one leg are each a bidirectional switch that cuts off a current flow when any of components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switches are each any of or a combination of the conventional bidirectional switches ofFIGS. 8 to 13. In the single-phase full-bridge circuit80on the side of the single-phase AC power supply, first switch sections provided in one leg are each a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. This is applicable also to first switch sections provided in every leg in a three-phase full-bridge circuit81on the side of the three-phase AC load. Such bidirectional switches are each any of or a combination of the bidirectional switches ofFIGS. 16 to 18. With such a configuration, the resulting power conversion apparatus does not require a DC link capacitor and a diode clamping circuit.

FIG. 60shows a power conversion apparatus similar to that ofFIG. 59but the switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply, and the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 61shows a power conversion apparatus similar to that ofFIG. 59but the switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply, and the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 62shows a power conversion apparatus similar to that ofFIG. 59but the switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by the MOSFET and the diode ofFIG. 56. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing only a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 63shows a power conversion apparatus similar to that ofFIG. 59but the switch sections provided in the two legs in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by the IGBT and the diode ofFIG. 58. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, thereby not requiring a DC link capacitor and a diode clamping circuit. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing only a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

Fourth Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 64shows a power conversion apparatus of the invention that drives a three-phase AC load from a three-phase AC power supply. The side of the three-phase AC power supply is connected with a filter82, which is configured by an inductor. A three-phase full-bridge circuit83on the power-supply side is connected with a three-phase full-bridge circuit85on the load side via a leg84configured by first switch sections and a capacitor. The capacitor here is extremely small in capacity compared with a conventional one because it is not for the conventional use, i.e., storage of power, but for absorbing any surge voltage to be generated at the time of switching of semiconductor device. In the three-phase full-bridge circuit83on the side of the three-phase AC power supply, second switch sections provided in one leg are each a bidirectional switch that cuts off a current flow when any of components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switches are each any of or a combination of the conventional bidirectional switches ofFIGS. 8 to 13. In the three-phase full-bridge circuit83on the side of the three-phase AC power supply, first switch sections provided in one leg are each a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. This is applicable also to first switch sections provided in every leg in a three-phase full-bridge circuit85on the side of the three-phase AC load, and to first switch sections provided in the leg84between the two three-phase full-bridge circuits. Such bidirectional switches are each any of or a combination of the bidirectional switches ofFIGS. 16 to 18. With such a configuration, the resulting power conversion apparatus does not require a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used.

FIG. 65shows a power conversion apparatus similar to that ofFIG. 64but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply, the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load and the switch sections disposed between the two three-phase full-bridge circuits are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 66shows a power conversion apparatus similar to that ofFIG. 64but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply, the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load, and the switch sections disposed between the two three-phase full-bridge circuits are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 67shows a power conversion apparatus similar to that ofFIG. 64but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by the MOSFET and the diode ofFIG. 56. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing only a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 68shows a power conversion apparatus similar to that ofFIG. 64but the switch sections provided in the two legs in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the three-phase full-bridge circuit on the side of the three-phase AC power supply are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by the IGBT and the diode ofFIG. 58. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing only a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

Fifth Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 69shows a power conversion apparatus of the invention that drives a three-phase AC load from a single-phase AC power supply. The side of the single-phase AC power supply is connected with a filter86, which is configured by an inductor. A single-phase full-bridge circuit87on the power-supply side is connected with a three-phase full-bridge circuit89on the load side via a leg88configured by first switch sections and a capacitor. The capacitor here is extremely small in capacity compared with a conventional one because it is not for the conventional use, i.e., storage of power, but for absorbing any surge voltage to be generated at the time of switching of semiconductor device. In a single-phase full-bridge circuit87on the side of the single-phase AC power supply, second switch sections provided in one leg are each a bidirectional switch that cuts off a current flow when any of components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switches are each any of or a combination of the conventional bidirectional switches ofFIGS. 8 to 13. In the single-phase full-bridge circuit87on the side of the single-phase AC power supply, first switch sections provided in one leg are each a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. This is applicable also to first switch sections provided in every leg in the three-phase full-bridge circuit89on the side of the three-phase AC load, and to first switch sections provided in the leg88between the single-phase full-bridge circuit and the three-phase full-bridge circuit. Such bidirectional switches are each any of or a combination of the bidirectional switches ofFIGS. 16 to 18. With such a configuration, the resulting power conversion apparatus does not require a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used.

FIG. 70shows a power conversion apparatus similar to that ofFIG. 69but the switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply, the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load, and the switch sections disposed between the single-phase full-bridge circuit and the three-phase full-bridge circuit are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 71shows a power conversion apparatus similar to that ofFIG. 69but the switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply, the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load, and the switch sections disposed between the single-phase full-bridge circuit and the three-phase full-bridge circuit are each a semiconductor device B. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 72shows a power conversion apparatus similar to that ofFIG. 69but the switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the MOSFET ofFIG. 13. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply, the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load, and the switch sections disposed between the single-phase full-bridge circuit and the three-phase full-bridge circuit are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by the MOSFET and the diode ofFIG. 56. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

FIG. 73shows a power conversion apparatus similar to that ofFIG. 69but the switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply are each a semiconductor device A using the IGBT ofFIG. 12. The switch sections provided in one leg in the single-phase full-bridge circuit on the side of the single-phase AC power supply, the switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load, and the switch sections disposed between the single-phase full-bridge circuit and the three-phase full-bridge circuit are each a semiconductor device B. The switch sections provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load are each a switch C configured by the IGBT and the diode ofFIG. 58. The semiconductor device A serves as a bidirectional switch that cuts off a current flow when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor device B serves to provide only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus becomes able to provide a three-phase load current between the switch sections and a motor using a semiconductor device, and prevent any short circuit of a capacitor by the switch thereof cutting off a current flow, thereby not requiring a DC link capacitor and a diode clamping circuit for storage of power as they have been conventionally used. The semiconductor device here is the one providing regenerative power and circulating power only in one specific way from the three-phase AC load when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load, and providing a current flow only in one specific way when any of the components connected thereto is not activated, i.e., a gate power supply, a control power supply, and a gate circuit.

Sixth Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 74shows a power conversion apparatus of the invention that drives a three-phase AC load from a three-phase AC power supply. The side of the three-phase AC power supply is connected with a filter90, which is configured by an inductor. A three-phase diode rectifier circuit91on the power-supply side is connected with a three-phase full-bridge circuit94on the load side via legs92and93. The leg92is the one configured by switch sections, and the leg93is the one configured by switch sections and a capacitor. The diode section provided in the three-phase diode rectifier circuit91on the side of the three-phase AC power supply is a diode. In the three-phase full-bridge circuit94on the side of the three-phase AC load, switch sections provided in every leg are each a bidirectional switch that provides only a specific unidirectional current when any of components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. This is applicable also to switch sections provided in the legs92and93between the three-phase diode rectifier circuit91and the three-phase full-bridge circuit94. The bidirectional switches are each any of or a combination of the conventional bidirectional switches ofFIGS. 16 to 18. The switch sections in the leg93are each in a power short-circuited mode when the power conversion apparatus is in the normal operation, and shape a near-sinusoidal waveform of input current, thereby being able to improve the power factor of total input and reduce harmonics of the input current. The switch sections provided in the leg93are each a bidirectional switch that provides only a specific unidirectional current when any of components is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, so that the regenerative power and the circulating power from a three-phase AC load can be directed back to the motor when the motor is with hard braking or is operated under light load. The switch sections provided in the leg93are operated in cooperation with the switch sections provided in the leg92, i.e., cut off a current flow bidirectionally, prevent a sudden surge of voltage at a capacitor terminal, and when the components connected to the semiconductor device, i.e., a gate power supply, a control power supply, and a gate circuit, are returned to operation, and direct the stored power back to the load by operating in cooperation with the switch sections in the three-phase full-bridge circuit94on the load side. Accordingly, the harmonics of the input current can be reduced, and the resulting power conversion apparatus becomes able to perform power conversion in small capacity.

FIG. 75shows a power conversion apparatus similar to that ofFIG. 74but the diode section provided in the three-phase diode rectifier circuit on the side of the three-phase AC power supply is a diode, and the switch sections are each a semiconductor device that provides only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The switch sections are those provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load, and those disposed between the three-phase diode rectifier circuit and the three-phase full-bridge circuit. The switch sections in a leg95are each in a power short-circuited mode when the power conversion apparatus is in the normal operation, improve the power factor of total input, and shape a near-sinusoidal waveform of input current, thereby being able to reduce harmonics of the input current. The regenerative power and the circulating power from a three-phase AC load can be directed back to the motor when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or when the motor is hard braking or is operated under light load. Accordingly, the harmonics of the input current can be reduced, and the resulting power conversion apparatus becomes able to perform power conversion by a capacitor with small capacity.

Seventh Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 76shows a power conversion apparatus of the invention that drives a three-phase AC load from a single-phase AC power supply. The side of the single-phase AC power supply is connected with a filter96, which is configured by an inductor. A single-phase diode rectifier circuit97on the power-supply side is connected with a three-phase full-bridge circuit100on the load side via legs98and99. The leg98is the one configured by switch sections, and the leg99is the one configured by switch sections and a capacitor. The diode section provided in the single-phase diode rectifier circuit97on the side of the single-phase AC power supply is a diode. In the three-phase full-bridge circuit100on the side of the three-phase AC load, switch sections provided in every leg are each a bidirectional switch that provides only a specific unidirectional current flow when any of components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. This is applicable also to switch sections disposed between the single-phase diode rectifier circuit and the three-phase full-bridge circuit. The bidirectional switches are each any of or a combination of the bidirectional switches ofFIGS. 16 to 22. The switch sections in the leg99are each in a power short-circuited mode when the power conversion apparatus is in the normal operation, and shape a near-sinusoidal waveform of input current, thereby being able to improve the power factor of total input and reduce harmonics of the input current. The switch sections provided in the leg99are each a bidirectional switch that provides only a specific unidirectional current when any of components is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, so that the regenerative power and the circulating power from a three-phase AC load can be directed back to the motor when the motor is with hard braking or is operated under light load. The switch sections provided in the leg99are operated in cooperation with the switch sections provided in the leg98, i.e., cut off a current flow bidirectionally, prevent a sudden surge of voltage at a capacitor terminal, and when the components connected to the semiconductor device, i.e., a gate power supply, a control power supply, and a gate circuit, are returned to operation, and direct the stored power back to the load by operating in cooperation with the switch sections in the three-phase full-bridge circuit100on the load side. Accordingly, the harmonics of the input current can be reduced, and the resulting power conversion apparatus becomes able to perform power conversion by the DC link capacitor with small capacity.

FIG. 77shows a power conversion apparatus similar to that ofFIG. 76but the diode section provided in the single-phase diode rectifier circuit on the side of the single-phase AC power supply is a diode, and the switch sections are each a semiconductor device that provides only a specific unidirectional current flow when any of the components connected to the semiconductor devices ofFIGS. 16 to 18is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The switch sections are those provided in every leg in the three-phase full-bridge circuit on the side of the three-phase AC load, and those disposed between the single-phase diode rectifier circuit and the three-phase full-bridge circuit. The switch sections in a leg101are each in a power short-circuited mode when the power conversion apparatus is in the normal operation, and shape a near-sinusoidal waveform of input current, thereby being able to improve the power factor of total input and reduce harmonics of the input current. The regenerative power and the circulating power from a three-phase AC load can be directed back to the motor when any of the components connected to the semiconductor device is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, or the motor is with hard braking or is operated under light load. Accordingly, the harmonics of the input current can be reduced, and the resulting power conversion apparatus becomes able to perform power conversion by a capacitor with small capacity.

Eighth Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 78shows a power conversion apparatus of the invention that drives a three-phase AC load from a three-phase AC power supply. The side of the three-phase AC power supply is connected with a filter102, which is configured by an inductor and a capacitor. The filter102on the side of the three-phase AC power supply is connected with the three-phase AC load by a direct power conversion circuit of a direct type, i.e., direct matrix converter,103. This direct matrix converter103is the one that performs power conversion into a three-phase AC load from a three-phase AC power supply, which includes nine first switch sections and three feed paths. Some of the nine first switches provided to the direct matrix converter103are each provided with a drain terminal, and second switch sections104are used to connect together the phases. The first switch sections are each a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switches are each any of or a combination of the conventional bidirectional switches ofFIGS. 16 to 18. The second switch sections104are each a bidirectional switch that provides a bidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus does not require a diode clamping circuit, which has been indispensable in a conventional AC-to-AC direct power conversion apparatus.

FIG. 79shows the circuit symbol of a bidirectional switch that provides a bidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. Such a bidirectional switch is used in each of the second switch sections104in the direct matrix converter103described above. The bidirectional switch is provided with a gate section, and two current paths, i.e., first and second sources. The bidirectional switch has a capability of controlling a current flow into the first and second sources depending on the signal combination provided to the gate section.

Especially when the second switch sections are each provided with the JFET made of silicon carbide, and the MESFET made of gallium nitride, the performance can be favorably improved.

FIG. 80shows a power conversion apparatus similar to that ofFIG. 78but the nine switch sections provided in the direct matrix converter are the semiconductor devices B ofFIGS. 16 to 18, and the switch sections serving to connect together the phases are each a semiconductor device C. The semiconductor devices B each serve as a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor C serves to provide a bidirectional current flow when any of the components connected to the semiconductor device ofFIG. 79is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. With such a configuration that the switch sections connecting together the phases each provide a bidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, the regenerative power from the load can be directed back to the load with safety, and this thus eliminates the need for a diode clamping circuit. Moreover, the regenerative power and the circulating power from the three-phase AC load can be provided between the switch sections and the motor when the three-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load. As such, the resulting power conversion apparatus does not require a diode clamping circuit, which has been indispensable in a conventional AC-to-AC direct power conversion apparatus.

Ninth Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 81shows a power conversion apparatus of the invention that drives a three-phase AC load from a single-phase AC power supply. The side of the single-phase AC power supply is connected with a filter105, which is configured by an inductor and a capacitor. The filter105on the side of the single-phase AC power supply is connected with the three-phase AC load by a direct power conversion circuit of a direct type, i.e., direct matrix converter,106. This direct matrix converter106is the one that performs power conversion into a three-phase AC load from a single-phase AC power supply, which includes six first switch sections and three feed paths. Some of the six first switches provided to the direct matrix converter106are each provided with a drain terminal, and second switch sections107are used to connect together the phases. The first switch sections are each a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switches are each any of or a combination of the conventional bidirectional switches ofFIGS. 16 to 18. The second switch sections107are each a bidirectional switch that provides a bidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus does not require a diode clamping circuit, which has been indispensable in a conventional AC-to-AC direct power conversion apparatus.

FIG. 82shows a power conversion apparatus similar to that ofFIG. 81but the six switch sections in the direct matrix converter are the semiconductor devices B ofFIGS. 16 to 18, and the switch sections serving to connect together the phases are each a semiconductor device C. The semiconductor devices B each serve as a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor C serves to provide a bidirectional current flow when any of the components connected to the semiconductor device ofFIG. 79is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. With such a configuration that the switch sections connecting together the phases each provide a bidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, the regenerative power from the load can be directed back to the load with safety, and this thus eliminates the need for a diode clamping circuit. Moreover, the regenerative power and the circulating power from the three-phase AC load can be provided between the switch sections and the motor when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load. As such, the resulting power conversion apparatus does not require a diode clamping circuit, which has been indispensable in a conventional AC-to-AC direct power conversion apparatus.

Tenth Embodiment of Apparatus for Power Conversion from AC Power Supply to AC Load

FIG. 83shows a power conversion apparatus of the invention that drives a three-phase AC load from a single-phase AC power supply. The side of the single-phase AC power supply is connected with a filter108and a capacitor109. The filter108is configured by an inductor and a capacitor, and the capacitor109is for ripple suppression use in the single-phase AC. These components on the side of the single-phase AC power supply, i.e., the filter108and the capacitor109for ripple suppression use in the single-phase AC, are connected with the three-phase AC load by a direct power conversion circuit of a direct type, i.e., direct matrix converter,110. This direct matrix converter110is the one that performs power conversion into a three-phase AC load from a three-phase AC power supply, which includes nine first switch sections and three feed paths. Some of the nine first switches provided to the direct matrix converter110are each provided with a drain terminal, and second switch sections111are used to connect together the phases. The first switch sections are each a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The bidirectional switches are each any of or a combination of the conventional bidirectional switches ofFIGS. 16 to 18. The second switch sections111are each a bidirectional switch that provides a bidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. As such, the resulting power conversion apparatus does not require a diode clamping circuit, which has been indispensable in a conventional AC-to-AC direct power conversion apparatus.

FIG. 84shows a power conversion apparatus similar to that ofFIG. 83but the nine switch sections in the direct matrix converter are the semiconductor devices B ofFIGS. 16 to 18, and the switch sections serving to connect together the phases are each a semiconductor device C. The semiconductor devices B each serve as a bidirectional switch that provides only a specific unidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. The semiconductor C serves to provide a bidirectional current flow when any of the components connected to the semiconductor device ofFIG. 79is not activated, i.e., a gate power supply, a control power supply, and a gate circuit. With such a configuration that the switch sections connecting together the phases each provide a bidirectional current flow when any of the components connected thereto, i.e., semiconductor device, is not activated, i.e., a gate power supply, a control power supply, and a gate circuit, the regenerative power from the load can be directed back to the load with safety, and this thus eliminates the need for a diode clamping circuit. Moreover, the regenerative power and the circulating power from the three-phase AC load can be provided between the switch sections and the motor when the single-phase AC power supply suffers from sudden failures, when a momentary (short-time) power failure occurs, and when a momentary voltage drop occurs, or when the motor is with hard braking or is operated under light load. As such, the resulting power conversion apparatus does not require a diode clamping circuit, which has been indispensable in a conventional AC-to-AC direct power conversion apparatus.