Patent Description:
The present disclosure relates to a motor driving apparatus and an air conditioner including the same, and more particularly to a motor driving apparatus capable of determining whether a switching device for switching connection of a motor operates abnormally, and an air conditioner including the same.

An air conditioner is an apparatus that discharges cool or hot air into a room in order to adjust room temperature and to purify air in the room, thereby providing a comfortable room environment to users. Generally, the air conditioner includes an indoor device installed in the room, the indoor device including a heat exchanger, and an outdoor device for supplying refrigerant to the indoor device, the outdoor device including a compressor and a heat exchanger.

<CIT> (hereinafter referred to as a "prior art") discloses a switching device for switching motor windings to Y-connection and Δ-connection in order to improve power conversion efficiency or a motor driving efficiency when a compressor motor of a compressor is driven.

However, in the prior art, a mechanical switch or an electrical switch is required as the switching device in order to switch windings of the motor to Y-connection and Δ-connection, and when repeatedly used, the switch may be damaged or its life may be degraded.

<CIT> is another related prior art document.

It is an object of the present disclosure to provide a motor driving apparatus capable of determining whether a switching device for switching connection of a motor operates abnormally, and an air conditioner including the same.

It is another object of the present disclosure to provide a motor driving apparatus capable of determining whether a switching device operates abnormally based on a winding resistance in a first connection and a winding resistance in a second connection by an operation of the switching device, and an air conditioner including the same.

It is yet another object of the present disclosure to provide a motor driving apparatus capable of increasing power conversion efficiency or motor driving efficiency when the switching device operates normally, and an air conditioner including the same.

It is still another object of the present disclosure to provide a motor driving apparatus capable of controlling the switching device to be operated in either the first connection or the second connection when the switching device operates abnormally, and an air conditioner including the same.

It is still another object of the present disclosure to provide a motor driving apparatus capable of determining whether a failure occurs in the motor, and an air conditioner including the same.

These objects are achieved with a motor driving apparatus as defined in independent claim <NUM>.

In accordance with an aspect of the present disclosure, the invention provides a motor driving apparatus and an air conditioner including the same, which include: an inverter having a plurality of switching elements, and configured to output alternating current (AC) power to a motor based on a switching operation; a switching device disposed between the inverter and the motor, and configured to switch windings of the motor to a first connection or a second connection; an output current detector configured to detect an output current output from the inverter; and a controller configured to control the inverter and the switching device, wherein in a switching device check mode, an output current at a first level is output from the inverter during a first period in a state in which the windings of the motor are connected in the first connection by an operation of the switching device, and the output current at the first level is output from the inverter during a second period after the first period in a state in which the windings of the motor are connected in the second connection by the operation of the switching device, based on a winding resistance of the motor in the first connection and a winding resistance of the motor in the second connection, the controller determines whether the switching device operates abnormally.

Meanwhile, the motor driving apparatus and the air conditioner including the same may further include an output voltage detector configured to detect an output voltage output from the inverter, wherein the controller may calculate a first winding resistance of the motor based on a first output voltage detected according to an output of the output current at the first level during the first period; may calculate a second winding resistance of the motor based on a second output voltage detected according to the output of the output current at the first level during the second period; and may determine whether the switching device operates abnormally based on the first winding resistance and the second winding resistance.

Meanwhile, the controller may calculate a ratio between the first winding resistance and the second winding resistance and may determine whether the switching device operates abnormally based on the calculated ratio.

Meanwhile, the controller may calculate ratios between the first winding resistance and the second winding resistance for each phase; and in response to ratios of all phases among the calculated ratios being within a predetermined range, the controller may determine that the switching device is normal, and may control the switching device to switch the windings of the motor from the first connection to the second connection according to an operating frequency of the motor.

Meanwhile, the controller may control the motor to continue to operate without stopping while the switching device switches the windings of the motor from the first connection to the second connection.

Meanwhile, the controller may control the operating frequency of the motor to decrease from a first frequency to a second frequency and then to increase again, while the switching device switches the windings of the motor from the first connection to the second connection.

Meanwhile, the controller may calculate ratios between the first winding resistance and the second winding resistance for each phase; and in response to a ratio of at least one phase among the calculated ratios falling outside a predetermined range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated in either the first connection or the second connection.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase falling outside a first range, and a range of the second winding resistance for each phase falling outside a second range, the controller may determine that the motor is out of order.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase being within the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is normal, and may control the switching device to switch the windings of the motor from the first connection to the second connection according to an operating frequency of the motor.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase being within the first range, and a range of the second winding resistance for each phase falling outside the second range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated only in the first connection.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase falling outside the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated only in the second connection.

Meanwhile, the controller may control the output current at the first level and the output current at the second level to be sequentially output from the inverter during the first period in a state in which the windings of the motor are connected in the first connection; and may control the output current at the first level and the output current at the second level to be sequentially output from the inverter during the second period in a state in which the windings of the motor are connected in the second connection.

Meanwhile, the motor driving apparatus and the air conditioner including the same may further include an output voltage detector configured to detect an output voltage output from the inverter, wherein the controller may calculate a first winding resistance of the motor based on an output voltage detected according to the output of the output current at the first level and the output current at the second level during the first period; may calculate a second winding resistance of the motor based on a second output voltage detected according to the output of the output current at the first level and the output current at the second level during the second period; and may determine whether the switching device operates abnormally based on the first winding resistance and the second winding resistance.

Meanwhile, the motor may be a three-phase motor; and the switching device may include a first to third relays which are electrically connected to each phase output of the inverter, wherein: a first terminal of the first relay, a first terminal of the second relay, and a first terminal of the third relay may be connected in parallel; one end of a first winding of the motor may be connected to a second terminal of the first relay; one end of a second winding of the motor may be connected to a second terminal of the second relay; one end of a third winding of the motor may be connected to a second terminal of the third relay; an opposite end of the first winding of the motor may be connected to a common terminal of the third relay; an opposite end of the second winding of the motor may be connected to a common terminal of the first relay; and an opposite end of the third winding of the motor may be connected to a common terminal of the second relay.

Meanwhile, for the first connection, the controller may control the common terminals of the first to third relays to be electrically connected to the respective first terminals of the first to third relays; and for the second connection, the controller may control the common terminals of the first to third relays to be electrically connected to the respective second terminals of the first to third relays.

In accordance with another aspect of the present disclosure, the above and other objects can be accomplished by providing a motor driving apparatus and an air conditioner including the same, which include: an inverter having a plurality of switching elements, and configured to output alternating current (AC) power to a motor based on a switching operation; a switching device disposed between the inverter and the motor, and configured to switch windings of the motor to a first connection or a second connection; an output current detector configured to detect an output current output from the inverter; and a controller configured to control the inverter and the switching device, wherein based on a first winding resistance of the motor in the first connection and a second winding resistance of the motor in the second connection, the controller determines whether the switching device operates abnormally.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase, wherein: in response to a range of the first winding resistance for each phase falling outside a first range, and a range of the second winding resistance for each phase falling outside a second range, the controller may determine that the motor is out of order: and in response to a range of the first winding resistance for each phase being within the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is normal, and may control the switching device to switch the windings of the motor from the first connection to the second connection according to an operating frequency of the motor.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase, wherein: in response to a range of the first winding resistance for each phase being within a first range, and a range of the second winding resistance for each phase falling outside a second range, the controller may determine that the switching device is abnormal and may control the windings of the motor to be operated only in the first connection: and in response to a range of the first winding resistance for each phase falling outside the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated only in the second connection.

Exemplary embodiments of the present disclosure will be described with reference to the accompanying drawings.

The terms "module" and "unit," when attached to the names of components are used herein to help the understanding of the components and thus they should not be considered as having specific meanings or roles. Accordingly, the terms "module" and "unit" may be used interchangeably.

<FIG> is a view showing the construction of an air conditioner according to an embodiment of the present disclosure.

As illustrated in <FIG>, the air conditioner according to the embodiment of the present disclosure is a large-sized air conditioner <NUM>, and may include a plurality of indoor devices <NUM> to <NUM>, a plurality of outdoor devices <NUM> and <NUM> connected to the plurality of indoor devices <NUM> to <NUM>, a plurality of remote controls <NUM> to <NUM> connected to the respective indoor devices, and a remote controller <NUM> for controlling the plurality of indoor devices and outdoor devices.

The remote controller <NUM> may be connected to the plurality of indoor devices <NUM> to <NUM> and the plurality of outdoor devices <NUM> and <NUM> to monitor and control operations thereof. In this case, the remote controller <NUM> may be connected to the plurality of indoor devices to perform operation setting, locking setting, schedule control, group control, and the like.

Any one of a stand type air conditioner, a wall mount type air conditioner, and a ceiling type air conditioner may be used as the air conditioner <NUM>, but a ceiling type air conditioner will be described below by way of example, for the convenience of description.

In addition, the air conditioner may further include at least one of a ventilator, an air purifier, a humidifier, and a heater, which may be operated in response to the operations of the indoor devices and the outdoor devices.

The outdoor devices <NUM> and <NUM> may include a compressor (not shown) for receiving and compressing a refrigerant, an outdoor heat exchanger (not shown) for heat exchange between the refrigerant and outside air, an accumulator (not shown) for extracting a gaseous refrigerant from the received refrigerant and supplying the refrigerant to the compressor, and a four-way valve (not shown) for selecting a refrigerant passage for a heating operation. In addition, the outdoor devices <NUM> and <NUM> may further include a plurality of sensors, valves, an oil recovery unit, etc., but a description thereof will be omitted below.

The outdoor devices <NUM> and <NUM> operate the compressor and the outdoor heat exchanger included therein, to compress or heat exchange the refrigerant according to a setting, and supply the refrigerant to the indoor devices <NUM> to <NUM>. The outdoor devices <NUM> and <NUM> are driven by a request from the remote controller <NUM> or the indoor devices <NUM> to <NUM>, and a cooling/heating capacity changes according to the driven outdoor devices, such that a number of operating outdoor devices and a number of operating compressors installed in the outdoor devices may change.

In this case, the following description will be made based on an example in which the plurality of outdoor devices <NUM> and <NUM> respectively supply the refrigerant to each of the indoor devices connected thereto, but depending on a connection structure of the outdoor devices and the indoor devices, the plurality of outdoor devices may be connected to each other to supply the refrigerant to the plurality of indoor devices.

The indoor devices <NUM> to <NUM> may be connected to any one of the plurality of outdoor devices <NUM> and <NUM>, to be supplied with the refrigerant and to discharge cool or hot air into a room. The indoor devices <NUM> to <NUM> include an indoor heat exchanger (not shown), an indoor fan (not shown), an expansion valve (not shown) in which the supplied refrigerant is expanded, and a plurality of sensors (not shown).

In this case, the outdoor devices <NUM> and <NUM> and the indoor devices <NUM> to <NUM> may be connected to each other via a communication line to transmit and receive data therebetween, and the outdoor devices <NUM> and <NUM> and the indoor devices <NUM> to <NUM> may be connected to the remote controller <NUM> via another communication line to operate under the control of the remote controller <NUM>.

The remote controls <NUM> to <NUM>, which are connected to the respective indoor devices, may transmit a user's control command to the indoor devices, and may receive and display information about the state of the indoor devices. In this case, the remote controls communicate by wire or wirelessly with the indoor devices depending on the manner in which the input devices are connected to the indoor devices, and in some cases a single remote control may be connected to the plurality of indoor devices such that settings of the plurality of indoor devices may be changed by the input of the single remote control.

In addition, each of the remote controls <NUM> to <NUM> may include a temperature sensor provided therein.

<FIG> is a schematic view showing an outdoor device and an indoor device of <FIG>.

Referring to the drawing, the air conditioner <NUM> is basically divided into an indoor device <NUM> and an outdoor device <NUM>.

The outdoor device <NUM> includes a compressor <NUM> for compressing refrigerant, a compressor motor 102b for driving the compressor, an outdoor heat exchanger <NUM> for cooling the compressed refrigerant, an outdoor blower <NUM> including an outdoor fan 105a disposed at one side of the outdoor heat exchanger <NUM> for accelerating the cooling of the refrigerant and a motor 105b for rotating the outdoor fan 105a, an expansion device <NUM> for expanding the condensed refrigerant, a cooling/heating switch valve <NUM> for changing the path of the compressed refrigerant, and an accumulator <NUM> for temporarily storing the gaseous refrigerant, removing moisture and foreign matter from the refrigerant, and supplying the refrigerant to the compressor under a predetermined pressure.

An indoor device <NUM> includes an indoor heat exchanger <NUM> disposed in a room for performing cooling/heating and an indoor blower <NUM> including an indoor fan 109a disposed at one side of the indoor heat exchanger <NUM> for accelerating the cooling of the refrigerant and a motor 109b for rotating the indoor fan 109a.

At least one indoor heat exchanger <NUM> may be installed. An inverter compressor or a fixed speed compressor may be used as the compressor <NUM>.

In addition, the air conditioner <NUM> may be configured as a cooler for cooling a room or as a heat pump for cooling or heating a room.

A single indoor device <NUM> and a single outdoor device <NUM> are shown in <FIG>. However, the present disclosure is not limited thereto. The present disclosure may also be applied to a multi-type air conditioner including a plurality of indoor devices and a plurality of outdoor devices or an air conditioner including a single indoor device and a plurality of outdoor devices.

The compressor <NUM> in the outdoor device <NUM> may be driven by a motor driving apparatus <NUM> for compressor driving, which drives a compressor motor <NUM>.

<FIG> is an internal block diagram schematically illustrating the air conditioner of <FIG>.

Referring to the drawing, the air conditioner <NUM> of <FIG> includes the compressor <NUM>, an outdoor fan 105a, an indoor fan 109a, a controller <NUM>, a discharge temperature sensor <NUM>, an outdoor temperature sensor <NUM>, an indoor temperature sensor <NUM>, and a memory <NUM>.

In addition, the air conditioner <NUM> may further include a compressor driver <NUM>, an outdoor fan driver <NUM>, an indoor fan driver <NUM>, a switch valve <NUM>, an expansion valve <NUM>, a display device <NUM>, and an input device <NUM>.

The compressor <NUM>, the outdoor fan 105a, and the indoor fan 109a are described above with reference to <FIG>.

The input device <NUM> has a plurality of operation buttons, and transmits a signal for an operating target temperature of the air conditioner <NUM> to the controller <NUM>.

The display device <NUM> may display an operating state of the air conditioner <NUM>.

The memory <NUM> may store data required for the operation of the air conditioner <NUM>.

The discharge temperature sensor <NUM> may sense refrigerant discharge temperature Tc at the compressor <NUM>, and may transmit a signal for the sensed refrigerant discharge temperature Tc to the controller <NUM>.

The outdoor temperature sensor <NUM> may sense outdoor temperature To, which is ambient temperature around the outdoor device <NUM> of the air conditioner <NUM>, and may transmit a signal for the sensed outdoor temperature To to the controller <NUM>.

The indoor temperature sensor <NUM> may sense indoor temperature Ti, which is ambient temperature around the indoor device <NUM> of the air conditioner <NUM>, and may transmit a signal for the sensed indoor temperature Ti to the controller <NUM>.

The controller <NUM> may control the air conditioner <NUM> to operate based on at least one of the sensed refrigerant discharge temperature Tc, the sensed outdoor temperature To, and the sensed indoor temperature Ti, and the input target temperature. For example, the controller <NUM> may control the air conditioner <NUM> to operate by calculating a final target superheat degree.

Further, in order to control operations of the compressor <NUM>, the indoor fan 109a, and the outdoor fan 105a, the controller <NUM> may control the compressor driver <NUM>, the outdoor fan driver <NUM>, and the indoor fan driver <NUM>, respectively, as illustrated herein.

For example, the controller <NUM> may output a corresponding speed reference signal to the compressor driver <NUM>, the outdoor fan driver <NUM>, or the indoor fan driver <NUM> based on the target temperature.

Further, based on each speed reference signal, the compressor motor (not shown), the motor <NUM>, the indoor fan motor 109b may operate at each target rotation speed.

The controller <NUM> may control the overall operation of the air conditioner <NUM>, in addition to the control of the compressor driver <NUM>, the outdoor fan driver <NUM>, or the indoor fan driver <NUM>.

For example, the controller <NUM> may control the operation of the cooling/heating switch valve <NUM> or a four-way valve.

Alternatively, the controller <NUM> may control the operation of expansion equipment or the expansion valve <NUM>.

<FIG> is an internal block diagram illustrating a motor driving apparatus according to an embodiment of the present disclosure; and <FIG> is an internal circuit diagram illustrating the motor driving apparatus of <FIG>.

Referring to the drawings, the motor driving apparatus <NUM> according to an embodiment of the present disclosure is used for driving a motor in a sensorless mode, and may be referred to as a power conversion device.

The motor driving apparatus <NUM> according to the embodiment of the present disclosure may include a converter <NUM>, an inverter <NUM>, an inverter controller <NUM>, a switching device <NUM>, a DC terminal voltage detector B, a DC terminal capacitor C, an output current detector E, and an output voltage detector F. In addition, the motor driving apparatus <NUM> may further include an input current detector A and the like.

The input current detector A may detect an input current is input from a commercial AC power source <NUM>. To this end, a current transformer (CT), shunt resistor and the like may be used as the input current detector A. The detected input current is, which is a pulse type discrete signal, may be input to the inverter controller <NUM>.

The converter <NUM> converts a voltage, having output from the commercial AC power source <NUM> and passed through the reactor L, into a DC voltage, and outputs the DC voltage. While the commercial AC power source <NUM> is shown as a three-phase AC power source, the commercial AC power may also be a single-phase AC power source. The internal structure of the converter <NUM> may change according to the type of the commercial AC power source <NUM>.

The converter <NUM> may include diodes without a switching element, such that the converter <NUM> may perform a rectification operation without performing a separate switching operation.

For example, six diodes may be arranged in the form of a bridge for the three-phase AC power source, and four diodes may be arranged in the form of a bridge for the single-phase AC power source.

The converter <NUM> may include six switching elements and six diodes for the three-phase AC power source, and in the case of single-phase AC power, a half-bridge type converter having two switching elements and four diodes may be used as the converter <NUM>.

When the converter <NUM> is provided with switching elements, the converter <NUM> may perform voltage boosting, power factor improvement, and DC voltage conversion according to a switching operation of the switching element.

The DC terminal capacitor C is disposed at the DC terminal, and stores the voltage output from the converter <NUM>. In the drawing, a single device is exemplified as the dc terminal capacitor C, but a plurality of devices may be provided to ensure device stability.

Further, while it is illustrated that the DC terminal capacitor C is connected to the output terminal of the converter <NUM>, the present disclosure is not limited thereto, and a DC voltage may be directly input to the DC terminal capacitor C.

For example, a DC voltage from a solar cell may be directly input to the DC terminal capacitor C or may be DC/DC converted and then input to the DC terminal capacitor C. The following description will be based on parts illustrated in the figure.

Both terminals n1-n2 of the DC terminal capacitor may be referred to as DC terminals or DC link terminals since DC voltage is stored in the DC terminal capacitor.

The dc terminal voltage detector B may detect a voltage Vdc applied between both terminals of the DC terminal capacitor C. To this end, the DC terminal voltage detector B may include a resistor, an amplifier, and the like. The detected DC terminal voltage Vdc, which is a pulse type discrete signal, may be input to the controller <NUM>.

The inverter <NUM> may include a plurality of inverter switching elements Sa ~ Sc and S'a ~ S'c, and may convert the DC voltage Vdc at the DC terminal into three-phase AC voltages Va, Vb, and Vc according to on/off operations of the switching elements Sa ~ Sc and S'a ~ S'c and output the voltages to the three-phase synchronous motor <NUM>.

In the inverter <NUM>, the upper arm switching element Sa, Sb, Sc and the lower arm switching element S'a, S'b, and S'c which are connected in series with each other form a pair, and a total of three pairs of upper and lower arm switching elements are connected in parallel with each other Sa&S'a, Sb&S'b, and Sc&S'c. Diodes are connected in reverse parallel to each of the switching elements Sa, S'a, Sb, S'b, Sc, and S'c.

The switching elements in the inverter <NUM> are turned on/off based on the inverter switching control signal Sic from the inverter controller <NUM>. Thus, the three-phase AC voltages of predetermined frequencies are output to the three-phase synchronous motor <NUM>.

The inverter controller <NUM> may control the switching operation of the inverter <NUM> in a sensorless mode. To this end, the inverter controller <NUM> may receive an output current io detected by the output current detector E.

In order to control the switching operation of the inverter <NUM>, the inverter controller <NUM> may output an inverter switching control signal Sic to the inverter <NUM>. The inverter switching control signal Sic is a pulse width modulation (PWM)-based switching control signal, and is generated based on the output current io detected by the output current detector E and the generated signal is output. An operation of outputting the inverter switching control signal Sic in the inverter controller <NUM> will be descried in detail later with reference to <FIG>.

The output current detector E detects the output current io flowing between the inverter <NUM> and the three-phase motor <NUM>. That is, the output current detector E detects a current flowing through the motor <NUM>. The output current detector E may detect all three phase output currents ia, ib, and ic, or may detect two phase output currents using three phase equilibrium.

The output current detector E may be disposed between the inverter <NUM> and the motor <NUM>, and may use a current transformer (CT), a shunt resistor, and so on for current detection.

When the shunt resistor is used, three shunt resistors may be disposed between the inverter <NUM> and the synchronous motor <NUM>, or one end thereof may be connected to the respective three lower arm switching element S'a, S'b, and S'c of the inverter <NUM>.

Further, two shunt resistors may also be used based on three phase equilibrium. In the case where one shunt resistor is used, the shunt resistor may be disposed between the capacitor C and the inverter <NUM>.

The detected output current io, which is a pulse type discrete signal, may be applied to the inverter controller <NUM>, and the inverter switching control signal Sic may be generated based on the detected output current io. In the following description, the detected output current io may correspond to three-phase output currents ia, ib, and ic.

The output voltage detector F may detect an output voltage vo output from the inverter <NUM>. Specifically, the output voltage detector F may detect each phase output voltage vo output from the inverter. To this end, the output voltage detector F may include a resistor, an amplifier, and the like. The detected output voltage vo, as a pulse type discrete signal, may be input to the inverter controller <NUM>.

The three-phase motor <NUM> includes a stator and a rotor. All three phase AC voltages of predetermined frequencies are applied to coils of all three phase (a-phase, b-phase, and c-phase) stators to rotate the rotor.

For example, the motor <NUM> can include a surface-mounted permanent-magnet synchronous motor (SMPMSM), an interior permanent magnet synchronous motor (IPMSM), a synchronous reluctance motor (Synrm) and the like. The SMPMSM and IPMSM are permanent magnet synchronous motors (PMSMs) employing a permanent magnet and the Synrm has no permanent magnet.

Further, the switching device <NUM> is disposed between the inverter <NUM> and the motor <NUM>, and may switch windings of the motor <NUM> to a first connection or a second connection.

Here, the first connection may be Y-connection, and the second connection may be Δ-connection.

To this end, the switching device <NUM> may include three relays SW1 to SW3 respectively connected between three-phase output terminals of the inverter <NUM> and three-phase coils CA, Cb, and CC.

That is, the switching device <NUM> may include first to third relays SW1 to SW3 which are electrically connected to the respective phase outputs.

If the motor <NUM> operates at a speed less than or equal to a first speed or a first operating frequency, the switching device <NUM> may operate for the motor <NUM> to be in the first connection; and if the motor <NUM> operates at a speed exceeding the first speed or the first operating frequency, the switching device <NUM> may operate for the motor <NUM> to be in the second connection, thereby increasing the power conversion efficiency or motor driving efficiency.

Particularly, at a low speed less than or equal to the first speed or the first operating frequency, the power conversion efficiency or motor driving efficiency may be improved.

Meanwhile, the motor driving device <NUM> according to an embodiment of the present disclosure includes: an inverter <NUM> having a plurality of switching elements Sa ~ Sc and S'a ~ S'c, and configured to output alternating current (AC) power to a motor based on a switching operation; a switching device <NUM> disposed between the inverter <NUM> and the motor <NUM>, and configured to switch windings of the motor <NUM> to a first connection or a second connection; an output current detector E configured to detect an output current io output from the inverter <NUM>; and a controller <NUM> or an inverter controller <NUM> configured to control the inverter <NUM> and the switching device <NUM>, in which in a switching device check mode for inspecting the switching device <NUM>, the output current io at a first level Lvn1 is output from the inverter <NUM> during a first period Pn1 while the windings of the motor <NUM> are connected in a first connection by an operation of the switching device <NUM>; and the output current io at the first level Lvn1 is output from the inverter <NUM> during a second period Pn2 after the first period Pn1 while the windings of the motor <NUM> are connected in a second connection by the operation of the switching device <NUM>. Accordingly, it is possible to determine an abnormal operation of the switching device <NUM> for switching the connection of the motor <NUM>. A detailed description thereof will be given later with reference to <FIG> and the following figures.

<FIG> is an internal block diagram illustrating an inverter controller of <FIG>.

Referring to <FIG>, the inverter controller <NUM> may include an axis transformation unit <NUM>, a speed calculator <NUM>, a current reference generator <NUM>, a voltage reference generator <NUM>, an axis transformation unit <NUM>, and a switching control signal output unit <NUM>.

The axis transformation unit <NUM> receives the three-phase output currents ia, ib, and ic detected by the output current detector E and transforms the received output currents ia, ib, and ic into two-phase currents iα and iβ of a stationary coordinate system.

Meanwhile, the axis transformation unit <NUM> may transform the two-phase currents iα and iβ of the stationary coordinate system into two-phase currents id and iq of a rotating coordinate system.

The speed calculator <NUM> may output a calculated position θ̂r and a calculated speed ω̂r based on the two-phase currents iα and iβ of the stationary coordinate system which is transformed by the axis transformation unit <NUM>.

Meanwhile, the current reference generator <NUM> generates a current reference value i*q based on the calculated speed ω̂r and a speed reference value ω*r. For example, a PI controller <NUM> of the current reference generator <NUM> may perform PI control based on a difference between the calculated speed ω̂r and the speed reference value ω*r, and may generate a current reference value i*q. Although a q-axis current reference value i*q is shown as the current reference value in the figure, it is possible to generate a d-axis current reference value i*d together with the q-axis current reference value i*q. The d-axis current reference value i*d may be set to <NUM>.

Meanwhile, the current reference generator <NUM> may further include a limiter (not shown) for limiting the level of the current reference value i*q such that the current reference value i*q does not exceed an allowable range.

The voltage reference generator <NUM> generates d-axis and q-axis voltage reference values V*d and V*q based on d-axis and q-axis currents id and iq axis-transformed into a two-phase rotating coordinate system by the axis transformation unit and the current reference value i*d and i*q generated by the current reference generator <NUM>. For example, a PI controller <NUM> of the voltage reference generator <NUM> may perform PI control based on the difference between the q-axis current iq and the q-axis current reference value i*q to generate a q-axis voltage reference value V*q. In addition, a PI controller <NUM> of the voltage reference generator <NUM> may perform PI control based on the difference between the d-axis current id and the d-axis current reference value i*d to generate a d-axis voltage reference value V*d. Meanwhile, the voltage reference generator <NUM> may further include a limiter (not shown) for limiting levels of the d-axis and q-axis voltage reference values V*d and V*q such that the d-axis and q-axis voltage reference values V*d and V*q do not exceed allowable ranges.

Meanwhile, the generated d-axis and q-axis voltage reference values V*d and V*q are input to the axis transformation unit <NUM>.

The axis transformation unit <NUM> receives the calculated position θ̂r and the d-axis and q-axis voltage reference values V*d and V*q from the position estimator <NUM> to perform axis transformation.

First, the axis transformation unit <NUM> performs transformation from a two-phase rotating coordinate system to a two-phase stationary coordinate system. At this time, the position θ̂r calculated by the position estimator <NUM> may be used.

Subsequently, the axis transformation unit <NUM> performs transformation from the two-phase stationary coordinate system to a three-phase stationary coordinate system. As a result, the axis transformation unit <NUM> outputs three-phase output voltage reference values V*a, V*b, and V*c.

The switching control signal output unit <NUM> generates and outputs a PWM-based inverter switching control signal Sic based on the three-phase output voltage reference values V*a, V*b, and V*c.

The output inverter switching control signal Sic may be converted into a gate driving signal by a gate driver (not shown), and may then be input to a gate of each switching element of the inverter <NUM>. As a result, the respective switching elements Sa, S'a, Sb, S'b, Sc, and S'c of the inverter <NUM> perform switching operations.

As described above, it is essential for the motor driving apparatus <NUM> to sense an output current io flowing to the motor, particularly a phase current, in order to perform vector control for driving the motor <NUM> through control of the inverter <NUM>.

The inverter controller <NUM> may control the motor <NUM> to produce a desired speed and a desired torque using the current command generator <NUM> and the voltage command generator <NUM> based on the sensed phase current.

<FIG> is a diagram referred to in the description of an operation of a switching device of <FIG>.

Referring to the drawing, (a) of <FIG> illustrates an example in which the switching device <NUM> operates such that the motor <NUM> is operated in Y-connection which is the first connection; and (b) of <FIG> illustrates an example in which the switching device <NUM> operates such that the motor <NUM> is operated in Δ-connection which is the second connection.

The switching device <NUM> includes the first to third relays SW1 to SW3 which are electrically connected to the respective phase outputs of the inverter <NUM>.

A first terminal naa of the first relay SW1, a first terminal nba of the second relay SW2, and a first terminal nca of the third relay SW3 are connected in parallel, in which one end nA of a first winding CA of the motor <NUM> is connected to the second terminal nab of the first relay SW1; one end nB of a second winding CB of the motor <NUM> is connected to the second terminal nbb of the second relay SW2; one end nC of a third winding CC of the motor <NUM> is connected to the second terminal ncb of the third relay SW3; the other end na of the first winding CA of the motor <NUM> is connected to a common terminal n3 of the third relay SW3; the other end nb of the second winding CB of the motor <NUM> is connected to a common terminal n1 of the first relay SW1; and the other end nc of the third winding CC of the motor <NUM> is connected to the common terminal n2 of the second relay SW2.

The second terminal nab of the first relay SW1 is connected to a U-phase output terminal ru of the inverter <NUM>, and the second terminal nbb of the second relay SW2 is connected to a V-phase output terminal rv of the inverter <NUM>, and the second terminal ncb of the third relay SW3 is connected to a W-phase output terminal rw of the inverter <NUM>.

As illustrated in (a) of <FIG>, for the first connection, the controller <NUM> may control the common terminals n1, n2, and n3 of the first to third relays SW1 to SW3 to be electrically connected to the respective first terminals naa, nba, and nca of the first to third relays SW1 to SW3.

In this manner, output currents of the U-, V-, and W-phases of the inverter <NUM> may respectively flow through the a-phase coil CA, the b-phase coil CB, and the c-phase coil CC of the motor <NUM> which is in Y-connection.

As illustrated in (b) of <FIG>, for the second connection, the controller <NUM> may control the common terminals n1, n2, and n3 of the first to third relays SW1 to SW3 to be electrically connected to the respective second terminals nab, nbb, and ncb of the first to third relays SW1 to SW3.

In this manner, output currents of the U-, V-, and W-phases of the inverter <NUM> may respectively flow through the b-phase coil CB, the c-phase coil CC, and the a-phase coil CA of the motor <NUM> which is in Δ-connection.

As a result, by the switching device <NUM>, it is possible to control the motor <NUM> to be operated in either the first connection or the second connection, thereby increasing the power conversion efficiency or driving efficiency of the motor <NUM>.

<FIG> are timing diagrams illustrating a winding switching operation of the switching device of <FIG>.

First, <FIG> is a timing diagram illustrating an example of a winding switching operation of the switching device of <FIG>.

Referring to the drawing, when an operating frequency of the motor <NUM> is less than f1, the switching device <NUM> may operate for the motor <NUM> to be in Y-connection as illustrated in (a) of <FIG>.

In the drawing, an example is illustrated in which during a period P1x up to a time point Txa, the switching device <NUM> operates for the motor <NUM> to be in Y-connection.

Then, during a period Px from Txa to Txb, the motor <NUM> may be stopped.

Subsequently, during a period P2x after the time point Txb, the switching device <NUM> may operate for the motor <NUM> to be in Δ-connection as illustrated in (b) of <FIG>.

For example, if an operating frequency of the motor <NUM> exceeds f1, the switching device <NUM> may operate for the motor <NUM> to be in Δ-connection; and during the period Px, the motor <NUM> may be stopped for Y to Δ conversion.

Next, <FIG> is a timing diagram illustrating another example of a winding switching operation of the switching device.

Referring to the drawing, when an operating frequency of the motor <NUM> is less than or equal to f1, the switching device <NUM> may operate for the motor <NUM> to be in Y-connection.

In the drawing, an example is illustrated in which during a period P1 up to a time point Ta, the switching device <NUM> operates for the motor <NUM> to be in Y-connection.

Then, during a period P2 from Ta to Tb, the controller <NUM> or the inverter controller <NUM> may control windings of the motor <NUM> to be switched from the first connection to the second connection.

Particularly, the controller <NUM> or the inverter controller <NUM> may control the motor <NUM> not to stop during the period P2, and may control an operating frequency of the motor <NUM> to temporarily decrease from the first frequency f1 to the second frequency f2.

Subsequently, during a period P3 after the time period Tb, the switching device <NUM> may operate for the motor <NUM> to be in Δ-connection as illustrated in (b) of <FIG>.

For example, if an operating frequency of the motor <NUM> exceeds f1, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to operate for the motor <NUM> to be in Δ-connection.

Specifically, during the period P3, the controller <NUM> or the inverter controller <NUM> may control the operating frequency of the motor <NUM>, which is temporarily decreased to the second frequency f2, to increase again.

The controller <NUM> of the inverter controller <NUM> may control the motor <NUM> to operate continuously without stopping while the switching device <NUM> switches the windings of the motor <NUM> from the first connection to the second connection. In this manner, the motor <NUM> does not stop during the switching operation of the switching device <NUM>, such that an operating efficiency of the motor <NUM> may be improved.

In this case, the period P2 of <FIG> is preferably shorter than the period Px of <FIG>. Accordingly, by temporarily decreasing the speed of the motor <NUM>, the windings of the motor <NUM> may be switched from the first connection to the second connection.

<FIG> is a flowchart illustrating an operating method of a motor driving apparatus according to an embodiment of the present disclosure.

Referring to the drawing, the controller <NUM> or the inverter controller <NUM> determines whether a mode of the motor driving apparatus <NUM> is a switching device check mode for inspecting the switching device included in the motor driving apparatus <NUM> (S910).

For example, the controller <NUM> or the inverter controller <NUM> may perform the switching device check mode before driving the motor <NUM>.

In another example, if a change in an operating frequency during the operation of the motor <NUM> is greater than or equal to a predetermined value, the controller <NUM> or the inverter controller <NUM> may perform the switching device check mode.

In the switching device check mode, the controller <NUM> or the inverter controller <NUM> may control the inverter <NUM> to output an output current at a first level during a first period in a state in which the windings of the motor <NUM> are connected in a first connection by the operation of the switching device <NUM> (S920).

Then, in the switching device check mode, the controller <NUM> or the inverter controller <NUM> may control the inverter <NUM> to output the output current at the first level, which is equal to the output current in the first connection, during a second period after the first period in a state in which the windings of the motor <NUM> are connected in a second connection by the operation of the switching device <NUM> (S930).

Subsequently, the controller <NUM> or the inverter controller <NUM> determines whether the switching device <NUM> operates abnormally based on a winding resistance of the motor <NUM> in the first connection and a winding resistance of the motor <NUM> in the second connection (S940).

For example, based on a first output voltage Lvn3, detected according to an output of the output current io at the first level Lvn1 during the first period Pn1, the controller <NUM> or the inverter controller <NUM> may calculate a first winding resistance of the motor <NUM>, and based on a second output voltage Lvn4, detected according to an output of the output current io at the first level Lvn1 during the second period Pn2, the controller <NUM> or the inverter controller <NUM> may calculate a second winding resistance of the motor <NUM>, and then may determine whether the switching device <NUM> operates abnormally based on the first winding resistance and the second winding resistance. Accordingly, the controller <NUM> or the inverter controller <NUM> may simply determine whether the switching device <NUM> for switching the windings of the motor <NUM> is abnormal.

Specifically, the controller <NUM> or the inverter controller <NUM> may calculate a ratio between the first winding resistance and the second winding resistance, and based on the calculated ratio, the controller <NUM> or the inverter controller <NUM> may determine whether the switching device <NUM> for switching the windings of the motor <NUM> operates abnormally.

Meanwhile, the controller <NUM> or the inverter controller <NUM> may calculate ratios between the first winding resistance and the second winding resistance for each phase, and if ratios of all the phases, among the calculated ratios, are within a predetermined range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is normal, and may control the switching device <NUM> to switch the windings of the motor <NUM> from the first connection to the second connection according to an operating frequency of the motor <NUM>. Accordingly, when the switching device <NUM> operates normally, the power conversion efficiency or driving efficiency of the motor <NUM> may be increased.

Referring to the drawing, the operating method of <FIG> is similar to the operating method of <FIG>, but there is a difference in that not only the output current at the first level but also output currents at a plurality of levels are output.

Accordingly, the operations <NUM> (S910), <NUM> (S920), <NUM> (S930), and <NUM> (S940) will be described with reference to <FIG>.

In the operation <NUM> (S920), in the switching device check mode, the controller <NUM> or the inverter controller <NUM> may control the inverter <NUM> to output the output current at the first level during a first period in a state in which the windings of the motor <NUM> are connected in the first connection by the operation of the switching device <NUM>.

Then, the controller <NUM> or the inverter controller <NUM> may control the inverter <NUM> to output an output current at a second level, which is different from the first level, during the first period after the output current at the first level is output, while the windings of the motor <NUM> are connected in the first connection by the operation of the switching device <NUM> (S922).

For example, the second level may be higher than the first level.

Subsequently, in the switching device check mode, the controller <NUM> or the inverter controller <NUM> may control the inverter <NUM> to output the output current at the first level during a second period in a state in which the windings of the motor <NUM> are connected in a second connection by the operation of the switching device <NUM> (S930).

Next, the controller <NUM> or the inverter controller <NUM> may control the inverter <NUM> to output the output current at the second level, which is different from the first level, during the second period after the output current at the first level is output, while the windings of the motor <NUM> are connected in the second connection by the operation of the switching device <NUM> (S932).

The first level and the second level in the second connection may be equal to the first level and the second level in the first connection, respectively.

Then, based on a winding resistance of the motor <NUM> in the first connection and the winding resistance of the motor <NUM> in the second connection, the controller <NUM> or the inverter controller <NUM> may determine whether the switching device <NUM> operates abnormally (S940).

For example, the controller <NUM> or the inverter controller <NUM> may calculate a first winding resistance of the motor <NUM> based on an output voltage Lvm3 detected according to an output of an output current at a first level Lvm1 during a first period Pm1, and an output voltage Lvm4 detected according to an output of an output current at a second level Lvm2; and the controller <NUM> or the inverter controller <NUM> may calculate a second winding resistance of the motor <NUM> based on an output voltage Lvm5 detected according to the output of the output current at the first level Lvm1 during the first period Pm1 and the second period Pm2, and an output voltage Lvm6 detected according to the output of the output current at the second level Lvm2. Based on the first winding resistance and the second winding resistance, the controller <NUM> or the inverter controller <NUM> may determine whether the switching device <NUM> operates abnormally, thereby simply determining an abnormal operation of the switching device <NUM> for switching connection of the motor <NUM>.

Specifically, the controller <NUM> or the inverter controller <NUM> may calculate a ratio between the first winding resistance and the second winding resistance and may determine whether the switching device <NUM> operates abnormally based on the calculated ratio, thereby simply determining an abnormal operation of the switching device <NUM> for switching connection of the motor <NUM>.

Meanwhile, the controller <NUM> or the inverter controller <NUM> may calculate ratios between the first winding resistance and the second winding resistance for each phase, and if ratios of all the phases among the calculated ratios are within a predetermined range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is normal and may control the switching device <NUM> to switch the windings of the motor <NUM> from the first connection to the second connection according to an operating frequency of the motor <NUM>. Accordingly, when the switching device <NUM> operates normally, the power conversion efficiency or driving efficiency of the motor <NUM> may be increased.

<FIG> are diagrams referred to in the description of the operating method of <FIG> or <FIG>.

First, <FIG> is a diagram referred to in the description of the operating method of <FIG>.

Referring to the drawing, (a) of <FIG> illustrates an output current ina, particularly a phase current, which is output from the inverter <NUM>.

During the period Pn1, the inverter controller <NUM> may control the inverter <NUM> to output an output current at the first level Lvn1 while the windings of the motor <NUM> are connected in the first connection by the operation of the switching device <NUM>.

A period Pns after the period P1 may be a period of conversion from the first connection to the second connection, in which a current may not be output from the inverter <NUM>.

Unlike the drawing, a current at a lower level than the first level Lvn1 may also be output during the period Pns. By the output of such output current, a speed of the motor <NUM> may be temporarily decreased during the period P2 of <FIG>.

Then, during the period P2 after the period Pns, the inverter controller <NUM> may control the inverter <NUM> to output the output current at the first level Lvn1 while the windings of the motor <NUM> are connected in the second connection by the operation of the switching device <NUM>.

In <FIG>, (b) illustrates a switching voltage Sna corresponding to the output current ina output from the inverter <NUM>, and an output voltage Snb which is an effective voltage.

Meanwhile, the output voltage Snb may correspond to the phase voltage.

During a period up to a time point tn1, which is an end point of the period Pn1, a pulse width of the switching voltage Sna increases and then is maintained at a constant level, and the output voltage increases and then is maintained at a third level Lvn3.

During the period Pns following the period Pn1, the output voltage becomes zero; and during the period P2 from a time point Tn2 after the period Pns, a pulse width of the switching voltage Sna increases and then is maintained at a constant level, and the output voltage increases and then is maintained at a fourth level Lvn4 which is lower than the third level Lvn3.

As illustrated in (b) of <FIG>, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance in the first connection and the second winding resistance in the second connection based on a difference in the output voltage Snb between the first connection and the second connection.

Meanwhile, the output current output from the inverter <NUM> is the same, such that if the operation of the switching device <NUM> is normal, the first winding resistance, having a greater output voltage SNb, is greater than the second winding resistance.

Based on such characteristics, the controller <NUM> or the inverter controller <NUM> may determine whether the switching device <NUM> operates abnormally.

Unlike <FIG> in which one phase current ina is illustrated, the controller <NUM> or the inverter controller <NUM> may control each of a U-phase current, a V-phase current, and a W-phase current at output terminals of each phase of the inverter <NUM> to sequentially have waveforms of <FIG>.

Based on a relationship of R=V/I, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance in the first connection and the second winding resistance in the second connection.

In this case, if the ratio between the winding resistance in the first connection and the winding resistance in the second connection is maintained within a predetermined range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is normal, and if the ratio falls outside the predetermined range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is abnormal.

Further, based on whether the first winding resistance in the first connection is within a first range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is normal or abnormal.

In addition, based on whether the second winding resistance in the second connection is within a second range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is normal or abnormal.

Next, <FIG> is a diagram referred to in the description of the operating method of <FIG>.

Referring to the drawing, (a) of <FIG> illustrates an output current ima, particularly a phase current, which is output from the inverter <NUM>.

During a period Pm1a in the period Pm1, the inverter controller <NUM> may control the inverter <NUM> to output the output current at the first level Lvm1 while the motor <NUM> is in the first connection by the operation of the switching device <NUM>.

Then, during a period Pm1b in the period Pm1, the inverter controller <NUM> may control the inverter <NUM> to output the output current at the second level Lvm2, which is greater than the first level Lvm1, while the motor <NUM> is in the first connection by the operation of the switching device <NUM>.

A period Pms following the period Pm1 is an interval of conversion from the first connection to the second connection, in which a current may not be output from the inverter <NUM>.

Unlike the drawing, a current at a lower level than the first level Lvm1 may also be output during the period Pms. By the output of such output current, a speed of the motor <NUM> may be temporarily decreased during the period P2 of <FIG>.

Then, during a period Pm2a in the period Pm2 after the period Pms, the inverter controller <NUM> may control the inverter <NUM> to output the output current at the first level Lvm1 while the motor <NUM> is in the second connection by the operation of the switching device <NUM>.

Subsequently, during a period Pm2b in the period Pm2, the inverter controller <NUM> may control the inverter <NUM> to output the output current at the second level Lvm2, which is greater than the first level Lvm1, while the motor <NUM> is in the second connection by the operation of the switching device <NUM>.

In <FIG>, (b) illustrates a switching voltage Sma corresponding to the output current ima output from the inverter <NUM>, and an output voltage Smb which is an effective voltage.

Meanwhile, the output voltage Smb may correspond to the phase voltage.

During the period Pm1a in the period Pm1, a pulse width of the switching voltage Sma increases and then is maintained at a constant level, and the output voltage increases and then is maintained at a third level Lvm3; and during the period Pm1b in the period Pm1, a pulse width of the switching voltage Sma increases again and then is maintained at a constant level, and the output voltage increases again and then is maintained at a fourth level Lvm4.

During the period Pms following the period Pm1, the output voltage becomes zero.

During the period Pm2a in the period P2 from a time point Tm2 after the period Pms, a pulse width of the switching voltage Sma increases and then is maintained at a constant level, and the output voltage increases and then is maintained at a fifth level Lvm5; and during the period Pm2b in the period Pm2, a pulse width of the switching voltage Sma increases again and then is maintained at a constant level, and the output voltage increases again and then is maintained at a sixth level Lvm6.

In this case, the fifth level Lvm5 may be lower than the third level Lvm3, and the sixth level Lvm6 may be lower than the fourth level Lvm4.

As illustrated in (b) of <FIG>, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance in the first connection and the second winding resistance in the second connection based on a difference in the output voltage Sbm between the first connection and the second connection.

Compared to <FIG>, by outputting the output current at various levels and calculating a winding resistance based on the output current, accuracy of the calculated winding resistance may be further improved.

Particularly, compared to <FIG>, by outputting the output current at various levels, an influence of a component other than a stator resistance may be removed, such that accuracy of the calculated winding resistance may be further improved.

Meanwhile, the output current output from the inverter <NUM> is the same, such that if the operation of the switching device <NUM> is normal, the first winding resistance having a greater output voltage Smb is greater than the second winding resistance.

Unlike <FIG> in which one phase current ima is illustrated, the controller <NUM> or the inverter controller <NUM> may control each of a U-phase current, a V-phase current, and a W-phase current at output terminals of each phase of the inverter <NUM> to sequentially have waveforms of <FIG>.

<FIG> is a schematic equivalent circuit diagram of the motor in the first connection and the second connection.

Referring to the drawing, (a) of <FIG> illustrates an equivalent circuit diagram of the motor <NUM> in Y-connection which is the first connection.

Meanwhile, if a voltage Va is applied to control a current Ia in Y-connection, a stator winding resistance is <NUM>/2Ra.

Then, (b) of <FIG> illustrates an equivalent circuit diagram of the motor <NUM> connected in A-connection which is the first connection.

Meanwhile, if the output current Ia is output in △-connection, the voltage Va is reduced to one third of a value in Y-connection, since the winding resistance is reduced to <NUM>/2Ra.

Accordingly, based on the difference, the controller <NUM> or the inverter controller <NUM> may confirm whether the connection is changed normally by the switching device <NUM>.

<FIG> is a diagram illustrating output voltages which are detected as phase currents at the first level and the second level in the first connection and the second connection are sequentially applied.

Referring to the drawing, as U-phase, V-phase, and W-phase output currents at the first level Lvm1 and the second level Lvm2 are output in the first connection during a period Poa of <FIG>, a U-phase output voltage during a period Poa1, a V-phase output voltage during a period Poa2, and a W-phase output voltage during a period Poa3 are detected.

As illustrated in the drawing, each of the U-phase, V-phase, and W-phase output voltages during the period Poa may have two voltage levels.

Based on each of the U-phase, V-phase, and W-phase output currents at the first level Lvm1 and the second level Lvm2 and each of the U-phase, V-phase, and W-phase output voltages in the first connection, the controller <NUM> or the inverter controller <NUM> may calculate a first winding resistance of each of the U-phase, V-phase, and W-phase.

Then, as the U-phase, V-phase, and W-phase output currents at the first level Lvm1 and the second level Lvm2 are output in the second connection during a period Pob of <FIG>, the U-phase output voltage during a period Pob1, the V-phase output voltage during a period Pob2, and the W-phase output voltage during a period Pob3 are detected.

As illustrated in the drawing, each of the U-phase, V-phase, and W-phase output voltages during the period Pob may have two voltage levels.

Based on each of the U-phase, V-phase, and W-phase output currents at the first level Lvm1 and the second level Lvm2 and each of the U-phase, V-phase, and W-phase output voltages in the second connection, the controller <NUM> or the inverter controller <NUM> may calculate a second winding resistance of each of the U-phase, V-phase, and W-phase.

Further, the controller <NUM> or the inverter controller <NUM> may determine whether the switching device <NUM> is abnormal based on the first winding resistance and the second winding resistance of each of the U-phase, V-phase, and W-phase.

<FIG> is a diagram illustrating the first winding resistance and the second winding resistance of each of the U-phase, V-phase, and W-phase, and a ratio therebetween, in the case where the switching device <NUM> operates normally.

Referring to the drawing, a U-phase winding resistance, a V-phase winding resistance, and a W-phase winding resistance in the first connection may be <NUM>Ω, <NUM>Ω, and <NUM>Ω, respectively.

Each of the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance may correspond to a winding resistance corresponding to an a-phase winding CA, a winding resistance corresponding to a b-phase winding CB, and a winding resistance corresponding to a c-phase winding CC of <FIG>.

Meanwhile, a U-phase winding resistance, a V-phase winding resistance, and a W-phase winding resistance in the second connection may be <NUM>. 41Ω, <NUM>Ω, and <NUM>Ω, respectively.

In this regard, a U-phase winding resistance ratio, a V-phase winding resistance ratio, and a W-phase winding resistance ratio, which are winding resistance ratios of the first connection to the second connection, may be <NUM>, <NUM>, and <NUM>, respectively.

That is, when the switching device <NUM> operates normally, a first range, which is a normal range of the winding resistance in the first connection, is preferably approximately <NUM>Ω to <NUM>Ω; a second range, which is a normal range of the winding resistance in the second connection, is preferably approximately <NUM>Ω to <NUM>Ω; and a third range, which is a normal range of the winding resistance ratios of the first connection to the second connection is preferably approximately <NUM>Ω to <NUM>Ω.

Based on such data of <FIG>, the controller <NUM> or the inverter controller <NUM> may determine abnormality of the switching device <NUM>.

For example, the controller <NUM> or the inverter controller <NUM> may calculate ratios between the first winding resistance and a second winding resistance for each of the U-phase, V-phase, and W-phase; and among the calculated ratios, if a ratio of at least one phase falls outside a predetermined range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is abnormal, and may control the windings of the motor <NUM> to be operated in at least either the first connection or the second connection. As described above, if the switching device <NUM> is abnormal, the controller <NUM> or the inverter controller <NUM> may control the windings of the motor <NUM> to be operated only in any one connection, thereby allowing the motor <NUM> to perform an emergency operation.

Meanwhile, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance and the second winding resistance for each of the U-phase, V-phase, and W-phase; and if a range of the first winding resistance for each of the U-phase, V-phase, and W-phase falls outside a first range, and a range of the second winding resistance for each of the U-phase, V-phase, and W-phase falls outside a second range, the controller <NUM> or the inverter controller <NUM> may determine that the motor <NUM> is out of order, thereby simply determining a failure of the motor <NUM>.

Meanwhile, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance and the second winding resistance for each of the U-phase, V-phase, and W-phase; and if a range of the first winding resistance for each of the U-phase, V-phase, and W-phase is within a first range, and a range of the second winding resistance for each of the U-phase, V-phase, and W-phase is within a second range, the controller <NUM> or the inverter controller <NUM> may determine that the motor <NUM> is normal, and may control the switching device <NUM> to switch the windings of the motor <NUM> from the first connection to the second connection according to an operating frequency of the motor <NUM>. Accordingly, if the switching device <NUM> operates normally, the power conversion efficiency or driving efficiency of the motor <NUM> may be increased.

Meanwhile, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance and the second winding resistance for each of the U-phase, V-phase, and W-phase; and if a range of the first winding resistance for each of the U-phase, V-phase, and W-phase is within a first range, and if a range of the second winding resistance for each of the U-phase, V-phase, and W-phase falls outside a second range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is abnormal, and may control the windings of the motor <NUM> to be operated only in the first connection. Accordingly, if the switching device <NUM> is abnormal, the controller <NUM> or the inverter controller <NUM> controls the windings of the motor <NUM> to be operated only in any one connection, thereby allowing the motor <NUM> to perform an emergency operation.

Meanwhile, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance and the second winding resistance for each of the U-phase, V-phase, and W-phase; and if a range of the first winding resistance for each of the U-phase, V-phase, and W-phase falls outside a first range, and if a range of the second winding resistance for each of the U-phase, V-phase, and W-phase is within a second range, the controller <NUM> or the inverter controller <NUM> may determine that the switching device <NUM> is abnormal, and may control the windings of the motor <NUM> to be operated only in the second connection. Accordingly, if the switching device <NUM> is abnormal, the controller <NUM> or the inverter controller <NUM> controls the windings of the motor <NUM> to be operated only in any one connection, thereby allowing the motor <NUM> to perform an emergency operation.

<FIG> are diagrams illustrating the first winding resistance and the second winding resistance for each of the U-phase, V-phase, and W-phase, and a ratio therebetween, in the case where the first connection is switched to the second connection.

First, (a) of <FIG> illustrates an equivalent circuit diagram of the motor <NUM> in the case where one relay in the switching device <NUM> operates abnormally.

Then, (b) of <FIG> illustrates the first winding resistance in the case of (a) of <FIG>, the second winding resistance of each of the U-phase, V-phase, and W-phase, and a ratio therebetween.

Referring to the drawings, the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance in the first connection may be <NUM>Ω, <NUM>Ω, and <NUM>Ω, respectively.

Meanwhile, the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance in the second connection may be <NUM>Ω, <NUM>Ω, and <NUM>Ω, respectively.

In this regard, a U-phase winding resistance ratio, a V-phase winding resistance ratio, and a W-phase winding resistance ratio, which are winding resistance ratios of the first connection to the second connection may be <NUM>, <NUM>, and <NUM>, respectively.

As the winding resistance ratio of the first connection to the second connection is within a third range, which is a normal range, only for the V-phase, the controller <NUM> or the inverter controller <NUM> may determine that only the V-phase resistance ratio is normal, and the U-phase and W-phase resistance ratios are abnormal.

Meanwhile, as all the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance are within the first range which is a normal range, the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the first connection is normal.

Meanwhile, among the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance, only the V-phase winding resistance is within the second range which is a normal range, and the U-phase winding resistance and the W-phase winding resistance fall outside the second range, such that the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the second connection is abnormal.

Accordingly, in the case of (a) of <FIG>, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to be operated only in the first connection, instead of the second connection.

In <FIG>, (a) illustrates an equivalent circuit diagram of the motor <NUM> in the case where two relays in the switching device <NUM> operate abnormally.

As the winding resistance ratios of the first connection to the second connection fall outside a third range, which is a normal range, for all the three phases, the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> is abnormal.

Meanwhile, as all the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance are within the first range, which is a normal range, the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the first connection is normal.

Meanwhile, among the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance in the second connection, only the V-phase winding resistance is within the second range, which is a normal range, and the U-phase winding resistance and the W-phase winding resistance fall outside the second range, such that the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the second connection is abnormal.

In <FIG>, (a) illustrates an equivalent circuit diagram of the motor <NUM> in the case where three relays in the switching device <NUM> operate abnormally.

Then, (b) of <FIG> illustrates the first winding resistance in the case of (a) of <FIG>, the second winding resistance for each of the U-phase, V-phase, and W-phase, and a ratio therebetween.

The winding resistance ratios of the first connection to the second connection fall outside a third range, which is a normal range, for all the three phases, such that the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> is abnormal.

Meanwhile, all the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance in the first connection are within the first range, which is a normal range, such that the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the first connection is normal.

Meanwhile, all the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance in the second connection fall outside the second range which is a normal range, such that the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the second connection is abnormal.

<FIG> are diagrams illustrating the first winding resistance of each of the U-phase, V-phase, and W-phase, and a ratio therebetween, in the case where the second connection is switched to the first connection.

Meanwhile, all the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance in the first connection fall outside the first range which is a normal range, such that the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the first connection is abnormal.

Meanwhile, all the U-phase winding resistance, the V-phase winding resistance, and the W-phase winding resistance in the second connection are within the second range which is a normal range, such that the controller <NUM> or the inverter controller <NUM> may determine that the operation of the switching device <NUM> in the second connection is normal.

Accordingly, in the case of (a) of <FIG>, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to be operated only in the second connection, instead of the first connection.

<FIG> is a flowchart illustrating an operating method of a motor driving apparatus according to yet another embodiment of the present disclosure; and <FIG> are diagrams referred to in the description of the operation of <FIG>.

Referring to <FIG>, the operating method of <FIG> is similar to the operating method of <FIG>, but there is a difference in that operations <NUM> (S950) to <NUM> (S965) are further performed after the operation <NUM> (S930).

Accordingly, the operations <NUM> (S910), <NUM> (S920), and <NUM> (S930) will be described with reference to the above description of <FIG>.

While only the operations <NUM> (S910), <NUM> (S920), and <NUM> (S930) are illustrated herein, the present disclosure is not limited thereto, and an operation <NUM> (S950) may also be performed after the operations <NUM> (S910), <NUM> (S920), <NUM> (S922), <NUM> (S930), and <NUM> (S932) are performed.

Meanwhile, the controller <NUM> or the inverter controller <NUM> calculates the first winding resistance in the first connection and the second winding resistance in the second connection. Particularly, the controller <NUM> or the inverter controller <NUM> may calculate the first winding resistance in the first connection and the second winding resistance in the second connection for each of the U, V, and W phases.

Then, the controller <NUM> or the inverter controller <NUM> may determine whether the first winding resistance is within a first range and the second winding resistance is within a second range (S950).

As described above, the first range may be in a range of <NUM> to <NUM>, and the second range may be in a range of <NUM> to <NUM>.

Subsequently, if the first winding resistance is within the first range, and the second winding resistance is within the second range, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to switch the windings of the motor <NUM> from the first connection to the second connection according to an operating frequency of the motor <NUM> (S952).

Accordingly, when the switching device <NUM> operates normally, the power conversion efficiency or driving efficiency of the motor <NUM> may be increased.

Meanwhile, while the switching device <NUM> switches the windings of the motor <NUM> from the first connection to the second connection, the controller <NUM> or the inverter controller <NUM> may control the motor <NUM> to continue to operate without stopping. Accordingly, as the motor <NUM> does not stop during the switching operation of the switching device <NUM>, the operating efficiency of the motor <NUM> may be improved.

Meanwhile, while the switching device <NUM> switches the windings of the motor <NUM> from the first connection to the second connection, the controller <NUM> or the inverter controller <NUM> may control an operating frequency of the motor <NUM> to decrease from a first frequency to a second frequency and then to increase again. Accordingly, as the motor <NUM> does not stop during the switching operation of the switching device <NUM>, the operating efficiency of the motor <NUM> may be improved.

Meanwhile, if the operation <NUM> (S950) is not satisfied, the controller <NUM> or the inverter controller <NUM> determines whether the first winding resistance is within a first range and the second winding resistance falls outside a second range (S955).

Further, if the first winding resistance is within the first range, and the second winding resistance falls outside the second range, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to be operated only in the first connection and not to be operated in the second connection (S957). As described above, by controlling the switching device <NUM> to be operated only in any one connection when the switching device <NUM> operates abnormally, an emergency operation of the motor <NUM> may be performed.

Meanwhile, if the operation <NUM> (S955) is not satisfied, the controller <NUM> or the inverter controller <NUM> determines whether the first winding resistance falls outside the first range, and the second winding resistance is within the second range (S960).

Further, if the first winding resistance falls outside the first range, and the second winding resistance is within the second range, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to be operated only in the second connection and not to be operated in the first connection (S957). As described above, by controlling the switching device <NUM> to be operated only in any one connection when the switching device <NUM> operates abnormally, an emergency operation of the motor <NUM> may be performed.

Meanwhile, if the operation <NUM> (S960) is not satisfied, the controller <NUM> or the inverter controller <NUM> may determine that the first winding resistance falls outside the first range, and the second winding resistance falls outside the second range and may determine that the motor <NUM> is out of order (S965), thereby simply determining whether a failure occurs in the motor <NUM>.

In addition, when the motor <NUM> is out of order, the controller <NUM> or the inverter controller <NUM> may stop the operation of the motor <NUM> as well as the operation of the inverter <NUM> and the like, thereby preventing damage to a circuit element in the motor driving apparatus <NUM> and the like.

<FIG> illustrates various examples of an equivalent circuit diagram of the motor <NUM> in the case where the first winding resistance is within the first range, and the second winding resistance is within the second range.

In <FIG>, (a) illustrates an equivalent circuit diagram of the motor <NUM> in the first connection which is Y-connection; and (b) illustrates an equivalent circuit diagram of the motor <NUM> in the second connection which is A-connection.

As in the operation <NUM> (S952) of <FIG>, the controller <NUM> or the inverter controller <NUM> may control a switching operation between the first connection and the second connection according to an operating frequency of the motor <NUM>.

<FIG> illustrates various examples of an equivalent circuit diagram of the motor <NUM> in the case where the first winding resistance is within the first range, and the second winding resistance falls outside the second range.

In <FIG>, (a) corresponds to a case where there is an abnormality in three relays as illustrated in <FIG>; (b) corresponds to a case where there is an abnormality in two relays as illustrated in <FIG>; and (c) corresponds to a case where there is an abnormality in one relay as illustrated in <FIG>.

Accordingly, in the case of <FIG>, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to be operated only in the first connection and not to be operated in the second connection.

<FIG> illustrates various examples of an equivalent circuit diagram of the motor <NUM> in the case where the first winding resistance falls outside the first range, and the second winding resistance is within the second range.

Accordingly, in the case of <FIG>, the controller <NUM> or the inverter controller <NUM> may control the switching device <NUM> to be operated only in the second connection and not to be operated in the first connection.

Meanwhile, the motor driving apparatus <NUM> according to the embodiments of the present disclosure, which are described above with reference to <FIG>, may be applied to various home appliances in addition to the air conditioner <NUM> of <FIG>. For example, the motor driving apparatus <NUM> may be applied in various fields, such as a laundry treatment apparatus (washing machine, dryer, etc.), a refrigerator, a water purifier, a robot cleaner, a robot, a vehicle, a drone, and the like.

The motor driving apparatus and an air conditioner including the same according to an embodiment of the present disclosure may include a switching device disposed between an inverter and a motor, in which in a switching device check mode, an output current at a first level is output from the inverter during a first period in a state in which the windings of the motor are connected in the first connection by an operation of the switching device, and the output current at the first level is output from the inverter during a second period after the first period in a state in which the windings of the motor are connected in the second connection by the operation of the switching device. Accordingly, it is possible to determine whether the switching device for switching connection of the motor operates abnormally.

Meanwhile, based on a winding resistance of the motor in the first connection and a winding resistance of the motor in the second connection, the controller may determine whether the switching device operates abnormally, thereby simply determining an abnormal operation of the switching device based on the winding resistance in the first connection and the winding resistance in the second connection by the operation of the switching device.

Meanwhile, the motor driving apparatus and the air conditioner including the same may further include an output voltage detector configured to detect an output voltage output from the inverter, wherein the controller may calculate a first winding resistance of the motor based on a first output voltage detected according to an output of the output current at the first level during the first period; may calculate a second winding resistance of the motor based on a second output voltage detected according to the output of the output current at the first level during the second period; and may determine whether the switching device operates abnormally based on the first winding resistance and the second winding resistance, thereby simply determining an abnormal operation of the switching device for switching connection of the motor.

Meanwhile, the controller may calculate a ratio between the first winding resistance and the second winding resistance and may determine whether the switching device operates abnormally based on the calculated ratio, thereby simply determining an abnormal operation of the switching device for switching connection of the motor.

Meanwhile, the controller may calculate ratios between the first winding resistance and the second winding resistance for each phase; and in response to ratios of all phases among the calculated ratios being within a predetermined range, the controller may determine that the switching device is normal, and may control the switching device to switch the windings of the motor from the first connection to the second connection according to an operating frequency of the motor, thereby increasing the power conversion efficiency or motor driving efficiency when the switching device operates normally.

Meanwhile, the controller may control the motor to continue to operate without stopping while the switching device switches the windings of the motor from the first connection to the second connection. Accordingly, the motor does not stop operating when the switching device performs a switching operation, such that the operating efficiency of the motor may be improved.

Meanwhile, the controller may control the operating frequency of the motor to decrease from a first frequency to a second frequency and then to increase again, while the switching device switches the windings of the motor from the first connection to the second connection. Accordingly, the motor does not stop operating when the switching device performs a switching operation, such that the operating efficiency of the motor may be improved.

Meanwhile, the controller may calculate ratios between the first winding resistance and the second winding resistance for each phase; and in response to a ratio of at least one phase among the calculated ratios falling outside a predetermined range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated in either the first connection or the second connection. Accordingly, when the switching device is abnormal, the motor may be operated only in any one connection, such that an emergency operation of the motor may be performed.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase falling outside a first range, and a range of the second winding resistance for each phase falling outside a second range, the controller may determine that the motor is out of order, thereby simply determining a failure of the motor.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase being within the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is normal, and may control the switching device to switch the windings of the motor from the first connection to the second connection according to an operating frequency of the motor. Accordingly, when the switching device operates normally, the power conversion efficiency or motor driving efficiency may be increased.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase being within the first range, and a range of the second winding resistance for each phase falling outside the second range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated only in the first connection. Accordingly, by controlling the windings of the motor to be operated only in any one connection when the switching device is abnormal, an emergency operation of the motor may be performed.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase; and in response to a range of the first winding resistance for each phase falling outside the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated only in the second connection. Accordingly, by controlling the windings of the motor to be operated only in any one connection when the switching device is abnormal, an emergency operation of the motor may be performed.

Meanwhile, the controller may control the output current at the first level and the output current at the second level to be sequentially output from the inverter during the first period in a state in which the windings of the motor are connected in the first connection; and may control the output current at the first level and the output current at the second level to be sequentially output from the inverter during the second period in a state in which the windings of the motor are connected in the second connection. Accordingly, as output currents at various levels may be output, accuracy in determining an abnormal operation of the switching device for switching connection of the motor may be improved.

Meanwhile, the motor driving apparatus and the air conditioner including the same may further include an output voltage detector configured to detect an output voltage output from the inverter, wherein the controller may calculate a first winding resistance of the motor based on an output voltage detected according to the output of the output current at the first level and the output current at the second level during the first period; may calculate a second winding resistance of the motor based on a second output voltage detected according to the output of the output current at the first level and the output current at the second level during the second period; and may determine whether the switching device operates abnormally based on the first winding resistance and the second winding resistance, thereby simply determining an abnormal operation of the switching device based on the winding resistance in the first connection and the winding resistance in the second connection by the operation of the switching device.

Meanwhile, the motor may be a three-phase motor; and the switching device may include a first to third relays which are electrically connected to each phase output of the inverter, wherein: a first terminal of the first relay, a first terminal of the second relay, and a first terminal of the third relay may be connected in parallel; one end of a first winding of the motor may be connected to a second terminal of the first relay; one end of a second winding of the motor may be connected to a second terminal of the second relay; one end of a third winding of the motor may be connected to a second terminal of the third relay; an opposite end of the first winding of the motor may be connected to a common terminal of the third relay; an opposite end of the second winding of the motor may be connected to a common terminal of the first relay; and an opposite end of the third winding of the motor may be connected to a common terminal of the second relay. Accordingly, it is possible to control the motor to be operated in either the first connection or the second connection by the switching device, such that the power conversion efficiency or motor driving efficiency may be increased.

Meanwhile, for the first connection, the controller may control the common terminals of the first to third relays to be electrically connected to the respective first terminals of the first to third relays; and for the second connection, the controller may control the common terminals of the first to third relays to be electrically connected to the respective second terminals of the first to third relays. Accordingly, it is possible to control the motor to be operated in either the first connection or the second connection by the switching device, such that the power conversion efficiency or motor driving efficiency may be increased.

In accordance with another aspect of the present disclosure, the above and other objects can be accomplished by providing a motor driving apparatus and an air conditioner including the same, which include: an inverter having a plurality of switching elements, and configured to output alternating current (AC) power to a motor based on a switching operation; a switching device disposed between the inverter and the motor, and configured to switch windings of the motor to a first connection or a second connection; an output current detector configured to detect an output current output from the inverter; and a controller configured to control the inverter and the switching device, wherein based on a first winding resistance of the motor in the first connection and a second winding resistance of the motor in the second connection, the controller determines whether the switching device operates abnormally, thereby simply determining an abnormal operation of the switching device based on the winding resistance in the first connection and the winding resistance in the second connection by the operation of the switching device.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase, wherein: in response to a range of the first winding resistance for each phase falling outside a first range, and a range of the second winding resistance for each phase falling outside a second range, the controller may determine that the motor is out of order: and in response to a range of the first winding resistance for each phase being within the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is normal, and may control the switching device to switch the windings of the motor from the first connection to the second connection according to an operating frequency of the motor. Accordingly, it is possible to simply determine a failure of the motor or a normal operation of the switching device.

Meanwhile, the controller may calculate the first winding resistance and the second winding resistance for each phase, wherein: in response to a range of the first winding resistance for each phase being within a first range, and a range of the second winding resistance for each phase falling outside a second range, the controller may determine that the switching device is abnormal and may control the windings of the motor to be operated only in the first connection: and in response to a range of the first winding resistance for each phase falling outside the first range, and a range of the second winding resistance for each phase being within the second range, the controller may determine that the switching device is abnormal, and may control the windings of the motor to be operated only in the second connection. Accordingly, by controlling the windings of the motor to be operated only in any one connection, an emergency operation of the motor may be performed.

Claim 1:
A motor driving apparatus (<NUM>), comprising:
an inverter (<NUM>) having a plurality of switching elements, and configured to output alternating current, AC, power to a motor (<NUM>) based on a switching operation;
a switching device (<NUM>), disposed between the inverter (<NUM>) and the motor (<NUM>), configured to switch windings of the motor (<NUM>) to a first connection or a second connection;
an output current detector (E) configured to detect an output current output from the inverter (<NUM>); and
a controller (<NUM>, <NUM>) configured to control the inverter (<NUM>) and the switching device (<NUM>),
characterized in that
in a switching device check mode, an output current at a first level is output from the inverter (<NUM>) during a first period in a state in which the windings of the motor (<NUM>) are connected in the first connection by an operation of the switching device (<NUM>), and the output current at the first level is output from the inverter (<NUM>) during a second period after the first period in a state in which the windings of the motor (<NUM>) are connected in the second connection by the operation of the switching device (<NUM>),
wherein based on a winding resistance of the motor (<NUM>) in the first connection and a winding resistance of the motor (<NUM>) in the second connection, the controller (<NUM>, <NUM>) is configured to determine whether the switching device (<NUM>) operates abnormally.