Patent Description:
The efficiency of a rotating machine operated by an inverter device at variable speed is generally expressed by an efficiency curve obtained by changing the number of revolutions under constant load conditions, and the efficiency peaks in a certain rotation zone within a required rotation range. To achieve energy-saving of equipment, it is important to improve the efficiency curve in a wide range of rotation and reduce power loss of the rotating machine.

It is well known that, although the efficiency of a rotating machine decreases in a low-speed rotation zone, by providing a rotating machine with high inductance at the design phase, it is possible to reduce not only the current value itself but also harmonic components. This makes it possible to increase the efficiency in a low-speed rotation zone. However, the efficiency decreases in a high-speed rotation zone.

To solve this problem, there is a technology as disclosed in patent literature <NUM> wherein connections of stator windings are switched between the low-speed rotation zone and the high-speed rotation zone. When connections are switched during driving of the rotating machine, an arc occurs at the switching contact, causing the life of the contact to decrease. Patent literature <NUM> discloses a technology wherein a winding switching device comprises a compression coil (spring) and electrodes to avoid the occurrence of a contact arc.

Rotating machines mounted on automobiles, railroad vehicles, etc. need to have high power density to achieve light weight, and they meet this requirement by applying high current to generate high torque. When applying a winding switching device to such high-current uses, it is necessary to maintain a pressing force at the switching contact by means of a spring mechanism etc. so as to apply high current all the time. Accordingly, conventional switching devices became large.

Meanwhile, patent literature <NUM> discloses a structure wherein a plurality of movable bodies with different short-circuit wiring patterns are provided with respect to a contact of the winding terminal so as to operate the movable bodies to switch connections. However, in the disclosed structure, short-circuit wiring intersects in a complicated manner, making the fabrication difficult. Furthermore, to withstand high current, it is necessary to construct short-circuit wiring by use of a bus bar having a large conductor area. However, bus bar bending work and assembly are complicated resulting in a significant cost increase.

There is another way to construct a switching device using a relay; however, the size of the relay device increases as current becomes high, resulting in a cost increase. Also, there is a method of operating and sliding the short-circuit wiring or short-circuit board of the winding terminal. However, repeated switching operation will wear both parts, resulting in a short mechanical life. Furthermore, great actuator power is required to withstand sliding friction.

As a solution, it is possible to reduce wear and the actuator power by reducing the pressing force at the contact portion. In this case, however, electrical resistance at the contact portion increases, generating more heat at the contact portion and resulting in a decrease in the system efficiency. Therefore, in conventional switching devices, how to achieve a long life is another challenge.

In a winding switching device disclosed in patent literature <NUM>, a link mechanism is used to ensure a pressing force at the switching contact, avoid the sliding, and reduce wear. However, because a repulsion force of the spring works in the direction of pressing the contact during switching operation, great actuator power is required. Since a link mechanism is also necessary, the switching device becomes large, making it difficult to achieve a small size.

Patent literature <NUM> discloses an operating coil
driver circuitry, which includes a control circuitry that out-puts a trigger signal and a reference voltage; an operational amplifier that compares the reference voltage to a node voltage, in which the node voltage is directly related to current flowing through an operating coil of a switching device and the operational amplifier outputs a logic high signal when the node voltage is higher than the reference voltage and outputs a logic low signal when the node voltage is lower than the reference voltage; and a flip-flop that outputs a pulse-width modulated signal to instruct a switch to supply a desired current to the operating coil based at least in part on the trigger signal and the signal output by the operational amplifier.

Patent literature <NUM> discloses an electrical machine with coils or windings and a method that configures coils or windings of electric machines, for instance dynamically in response to operational condition and under load.

Therefore, an objective of the present invention is to provide a rotating machine drive system provided with a winding switching device wherein the rotating machine drive system has a relatively simple structure and is capable of reliably preventing wear at the electrical contact during switching and sliding and a vehicle using the rotating machine drive system.

To solve the above problem, the present invention is defined in the independent apparatus claim <NUM>, defining a rotating machine drive system,and the preferred embodiments in the dependent claims.

According to the present invention, it is possible to achieve a rotating machine drive system provided with a winding switching device, the rotating machine drive system having a relatively simple structure and capable of reliably preventing wear at the electrical contact during switching and sliding, and a vehicle using the rotating machine drive system.

This makes it possible to contribute to the reduction of the size of the rotating machine drive system and the vehicle, reduction of costs, and increase in reliability (long life).

Problems, structures, and advantageous effects other than the above will be clearly explained in the preferred embodiments described below.

Hereinafter, examples of the present invention will be described with reference to the drawings. In each drawing, the same sign is provided for the same structure and detailed description of overlapping parts will be omitted.

Description will be given below about the number of parallel connections in several different patterns. However, the present invention is not limited to such a structure and can apply to a structure wherein Y-connections with the different number of parallel connections are switched, a structure wherein the number of parallel connections of the Δ connection are switched, and a structure wherein the Y-connection and the Δ connection are switched.

Furthermore, the winding switching device has a cylindrical structure; however, it may be a planar structure or other structures. The rotating machine may be an induction machine, or a permanent magnet synchronous machine, winding-type synchronous machine, synchronous reluctance rotating machine, etc. The stator winding method may be concentrated winding or distributed winding. Also, the number of phases of the stator winding is not limited to those shown in the examples.

Furthermore, semiconductor switching elements of the inverter device are IGBTs (Insulated Gate Bipolar Transistors). However, the present invention is not limited to those, and they may be MOSFETs (Metal Oxide Semiconductor Field-Effect Transistors) or other power semiconductor devices.

Furthermore, the rotating machine control method is a vector control that does not use a speed detector or voltage detector. However, a control method that uses a speed detector or a voltage detector may be used.

Hereinafter, a first example of the present invention will be described with reference to <FIG>. <FIG> is a block diagram showing the overall structure of a rotating machine drive system according to example <NUM>. <FIG> shows the structure of a winding switching device according to a conventional technology, and <FIG> shows the characteristics of the rotating machine according to a conventional technology. <FIG> shows the operation of the 1Y/2Y switching device for one phase according to example <NUM>. <FIG> shows the comparison of advantages and disadvantages between the present invention and conventional technologies.

The overall structure of the rotating machine drive system according to example <NUM> will be described with reference to <FIG>. In <FIG>, an inverter device <NUM> comprises an inverter circuit <NUM> for converting direct-current power, which is output from a direct-current power source <NUM>, to alternating-current power and outputting the alternating-current power to a rotating machine <NUM>; a phase current detection circuit <NUM> for detecting current running through the rotating machine <NUM> connected to the inverter circuit <NUM>; and a control device <NUM> for performing inverter control (power conversion control) of the inverter circuit <NUM> based on the phase current information 106A detected by the phase current detection circuit <NUM> and using an applied voltage command pulse signal 108A, thereby operating the rotating machine <NUM> at variable speed.

The phase current detection circuit <NUM>, composed of a hall CT (Current Transformer) etc., detects three-phase current waveforms Iu, Iv, Iw of U-phase, V-phase, and W-phase current. However, all three-phase current does not have to be detected by the phase current detection circuit <NUM>: any two-phase current is detected and the other one phase current may be calculated based on the assumption that three-phase current is in an equilibrium status.

The inverter circuit <NUM> comprises an inverter main circuit <NUM> composed of a plurality of semiconductor switching elements, such as IGBTs, diodes (free-wheeling diodes), etc., and a gate driver <NUM> for generating a gate signal to the IGBTs of the inverter main circuit <NUM> based on the applied voltage command pulse signal 108A sent from the inverter control part <NUM>.

The rotating machine <NUM>, for example, composed of an induction machine having a plurality of windings or a permanent magnet synchronous machine, is designed so that the starting end and the end of a winding are pulled out and stored in the winding switching device <NUM> so that connections of the windings can be switched.

The winding switching device <NUM> has a circuit capable of switching connections of the windings of the rotating machine <NUM> and switches winding connections based on the signal output from the winding switching command part <NUM> when the rotation of the rotating machine <NUM> changes between the low-speed rotation zone and the high-speed rotation zone.

The control device <NUM> comprises an inverter control part <NUM> for generating an applied voltage command pulse signal 108A based on the phase current information 106A detected by the phase current detection circuit <NUM>, and a winding switching command part <NUM> for sending a connection switching signal to the winding switching device <NUM>.

In this example, the rotating machine drive system at least includes an inverter device <NUM>, a rotating machine <NUM>, and a winding switching device <NUM>.

Next, the structure of the winding switching device will be described with reference to <FIG>. Also, explanation will be given about the problems with conventional technologies, their solutions, and the principle of reducing the size of the winding switching device and increasing its service life, which is an objective of the present invention.

<FIG> is a schematic diagram showing the structure of the U-phase winding 150u of the stator of the rotating machine <NUM>, wherein starting ends (terminals) U1 and U2 and ends (terminals) U3 and U4 of two U-phase windings 150u1 and 150u2 are pulled out so as to switch the serial and parallel connections. The structure of the V-phase winding and the W-phase winding is the same and therefore, description is omitted. As shown in the upper drawing of <FIG>, starting end U1 and starting end U2, and end U3 and end U4 of the U-phase winding 150u are connected in parallel by short-circuit parts 141u1 and 141u2, respectively; parallel connections are also implemented in the V-phase and W-phase windings; and the three-phase neutral point <NUM> is connected in the Y letter shape. This configuration is referred to as "2Y-connection".

On the other hand, the configuration shown in the lower drawing of <FIG> is referred to as "1Y-connection", wherein end U3 of the U-phase winding 150u1 and starting end U2 of the U-phase winding 150u2 are connected in serial by the short-circuit part 141u1; serial connections are also implemented in the V-phase and W-phase windings; and the three-phase neutral point <NUM> is connected in the Y letter shape.

It is well known that system efficiency can be increased by use of the above-mentioned winding switching device so as to switch between 1Y-connection and 2Y-connection according to the number of revolutions n of the rotating machine <NUM>, as shown in <FIG>. Specifically, when the number of revolutions is small, increasing voltage by means of 1Y-connection will reduce current by half comparing the value with the conventional technology. As a result, conduction loss and switching loss of the semiconductor switching elements constituting the inverter circuit <NUM> decrease by half. Thus, the inverter efficiency and the system efficiency increase significantly, resulting in that energy saving can be achieved.

However, in the structure shown in <FIG>, winding terminals U1 to U4 and the short-circuit part <NUM> slide, and repeated switching operation will wear both of them, causing a mechanical life to become shortened. Also, actuator power is required to be large to withstand sliding friction.

As a solution, reducing the pressing force at the contact portion will reduce wear and the actuator power; however, electrical resistance at the contact portion will increase, generating more heat at the contact portion and decreasing the system efficiency. Therefore, in the conventional technology, achieving a long life is a challenge.

Another method is to use a relay to configure a switching device. However, as current becomes higher, the size of the relay device increases, resulting in a cost increase. Another method is to use a link mechanism, as shown in patent literature <NUM>, so as to ensure a pressing force at the switching contact, avoid the sliding, and reduce wear. However, great actuator power is required because a repulsion force of the spring works in the direction of pressing the contact during switching operation. Since a link mechanism is necessary, the switching device becomes large, and it is difficult to achieve a small size.

The above problems can be solved by adopting the winding switching device shown in <FIG>. Detailed description will be given about specific solutions and the principle of reducing the size of the winding switching device and increasing its service life, which is an objective of the present invention.

<FIG> shows the operation of the 1Y/2Y switching device for one phase (U-phase) according to the first example of the present invention. Hereinafter, as shown in <FIG>, the structure of the switching contact in this example will be described using the XYZ coordinate system wherein the horizontal direction is defined as an X-axis, the depth direction of the plane of paper is defined as a Y-axis, and the vertical direction is defined as a Z-axis.

The structure of the winding switching device shown in <FIG> is different from the conventional structure (<FIG>) in the point that a semi-moving element <NUM> is disposed between the winding terminals U1 to U4 and the moving element <NUM>. The semi-moving element <NUM> comprises a short-circuit part <NUM> (131u1, 131u2), an insulating part <NUM>, and a sliding part <NUM>, and the moving element <NUM> is composed of a rod <NUM> provided with a sliding part <NUM>.

As shown in <FIG>, starting end U1 and starting end U2, and end U3 and end U4 of the U-phase winding 150u are connected in parallel by short-circuit parts 131u1 and 131u2, respectively, thereby establishing a 2Y-connection. Herein, the protrusions downward in the Z direction of the semi-moving element sliding part <NUM> and the protrusions upward in the Z direction of the moving element sliding part <NUM> face to each other.

As shown in <FIG>, during switching, the moving element <NUM> slides in the X direction, releasing the opposed state of the protrusions of the semi-moving element sliding part <NUM> and the protrusions of the moving element sliding part <NUM>, thereby causing the semi-moving element <NUM> to slide in the Z direction. This movement eliminates the mechanical contact between the winding terminals U1 to U4 and the short-circuit part <NUM> (131u1, 131u2).

When the moving element <NUM> further slides in the X direction, as shown in <FIG>, the semi-moving element <NUM> slides in the X direction along with the moving element <NUM> while the side surface of the protrusions of the semi-moving element sliding part <NUM> come in contact with the side surface of the protrusions of the moving element sliding part <NUM>.

Then, as shown in <FIG>, when the semi-moving element <NUM> reaches the stopper <NUM>, only the moving element <NUM> keeps sliding in the X direction and stops at the time the protrusions of the semi-moving element sliding part <NUM> and the protrusions of the moving element sliding part <NUM> have faced to each other.

By this movement, end U3 of the U-phase winding 150u1 and starting end U2 of the U-phase winding 150u2 are connected in serial by the short-circuit part 131u1, thereby establishing a 1Y-connection.

The above-mentioned structure eliminates the sliding between the winding terminals U1 to U4 and the short-circuit part <NUM>. Accordingly, wear of both the winding terminals and the short-circuit part due to repeated switching operation can be avoided, resulting in a long mechanical life. Furthermore, since sliding friction is generated only at the contact portion between the semi-moving element sliding part <NUM> and the moving element sliding part <NUM>, by making the sliding part composed of material having a small friction coefficient, it is possible to achieve both the X-direction movement of the moving element <NUM> and the Z-direction movement of the semi-moving element even with small actuator power. As a result, it is possible to simultaneously achieve a small winding switching device and its long life.

Furthermore, when the protrusions of the semi-moving element sliding part <NUM> and the protrusions of the moving element sliding part <NUM> face to each other, a sufficient pressing force can be generated between the winding terminals U1 to U4 and the short-circuit part <NUM>. Thus, it is possible to suppress electrical resistance at the contact portion while avoiding the decrease in life due to sliding friction. Furthermore, since the semi-moving element <NUM> and the moving element <NUM> are made of simple cylindrical parts, unlike the link mechanism, increase in the number of parts or the size can be avoided. Thus, it is possible to provide a small winding switching device even in applications where large current will flow.

The semi-moving element short-circuit parts 131u1 and 131u2 are composed of cylindrical conductors. Both of them function to switch connection patterns of the terminals U1 to U4 and therefore need to be electrically insulated from each other. Therefore, in <FIG>, a predetermined insulation distance is provided between the short-circuit parts 131u1 and 131u2 in the X direction.

Moreover, it is desirable that material with low electrical resistance, such as brass and plated metal material, be used for the semi-moving element short-circuit parts 131u1 and 131u2.

Material for the semi-moving element sliding part <NUM> may be metal or resin, but metal is more desirable in terms of ensuring long-time durability. Also, it is desirable that material with a low friction coefficient and high degree of hardness be used. When using metal for making the semi-moving element sliding part <NUM>, a semi-moving element insulating part <NUM> needs to be provided so that electrical short-circuits will not occur between the semi-moving element short-circuit parts 131u1 and 131u2 via the semi-moving element sliding part <NUM>.

The insulating part <NUM> may be composed of a cylindrical collar or a sheet-like insulator wrapping around the sliding part <NUM>, or may be constructed so that an insulator is pasted on the inner periphery side of the short-circuit part <NUM> and then assembled onto the sliding part <NUM>. If the sliding part <NUM> is made of non-conductive material such as resin, an insulating part <NUM> does not need to be provided.

It is preferable that lubricant be applied to the portion where the semi-moving element sliding part <NUM> and the moving element sliding part <NUM> mechanically come into contact with each other or be filled into a space between the two sliding parts so as to reduce the friction coefficient during sliding. By doing so, actuator power can be small, so that a further smaller winding switching device can be achieved.

When using a grease as a lubricant, grease will adsorb abrasion powder generated at the sliding parts, so it is possible to avoid problems of a scuff at the sliding parts or electrical short-circuits caused by abrasion powder scattering in the terminals.

If using a structure where the inner periphery side is sealed with the semi-moving element sliding part <NUM>, lubricating oil can be filled. In this case, abrasion powder can be confined in the enclosed space and it is therefore possible to eliminate a problem of electrical short-circuits.

Thus, by providing a semi-moving element <NUM>, the electrical short-circuit function can be separated from the mechanically sliding function. As a result, taking measures for achieving a long life becomes easier.

The moving element rod <NUM> may be driven by a direct acting type linear actuator or by a drive mechanism using ball screws. Also applicable is a structure where the moving element sliding part <NUM> is a helical structure swirling around the X-axis, the semi-moving element sliding part <NUM> is also a helical structure swirling around the X-axis, and the moving element rod <NUM> is rotated by a rotary actuator, thereby changing the opposed state of both sliding parts as shown in <FIG>.

In other words, a rotating machine drive system according to this example comprises a rotating machine <NUM> having a plurality of windings, an inverter device <NUM> for operating the rotating machine <NUM> at variable speed, and a winding switching device <NUM> for switching connections of the plurality of windings of the rotating machine <NUM>. The winding switching device <NUM> comprises winding terminals U1 to U4, a semi-moving element <NUM> having a short-circuit part <NUM> that faces the winding terminals U1 to U4 and also having a sliding part <NUM> provided with first protrusions on the surface opposite from the surface having the short-circuit part <NUM>, and a moving element <NUM> facing the semi-moving element sliding part <NUM> and having a sliding part <NUM> provided with second protrusions on the surface facing the semi-moving element sliding part <NUM>. The moving element <NUM> is made to slide relative to the semi-moving element <NUM>, thereby changing the connections between the winding terminals U1 to U4 and the semi-moving element short-circuit part <NUM> and switching the connections of the plurality of windings of the rotating machine <NUM>.

The first protrusions and the second protrusions face to each other, and accordingly, the winding terminals U1 to U4 and the semi-moving element short-circuit part <NUM> mechanically come in contact with each other.

Furthermore, when an opposed state of the first protrusions and the second protrusions is changed to a non-opposed state, the winding terminals U1 to U4 and the semi-moving element short-circuit part <NUM> that have been in a mechanical contact state will enter a non-contact state.

Furthermore, the moving element <NUM> slides relative to the semi-moving element <NUM> while the first protrusions and the second protrusions come in contact with each other in a non-opposed state.

So far, description has been given about the problems with conventional technologies, their solutions, and the principle of reducing the size of the winding switching device and increasing its service life, which is an objective of the present invention. <FIG> shows the comparison of advantages and disadvantages between the present invention and conventional technologies. As shown in <FIG>, according to the present invention (this example), it is possible to provide a winding switching device having a great pressing force at the contact portion, low electrical resistance, a long mechanical life, and small actuator power. As a result, it is possible to contribute to the reduction of size and cost and the achievement of high reliability (long life) of a rotating machine drive system and a vehicle provided with the winding switching device.

Moreover, by constructing the rotating machine drive system according to this example as being an integrated traction motor system wherein a rotating machine <NUM>, an inverter device <NUM>, and a winding switching device <NUM> are integrated into one unit, it is possible to eliminate or shorten the wiring between devices. Consequently, the rotating machine drive system can be small and the reliability increases.

A second example of the present invention will be described with reference to <FIG> and <FIG>. <FIG> and <FIG> show the operation of the 1Y/2Y switching device for one phase according to example <NUM>.

<FIG> and <FIG> show the detailed structure shown in <FIG>. Specifically, the semi-moving element <NUM> comprises a short-circuit part <NUM> (131u1, 131u2), an insulating part <NUM>, a sliding part <NUM>, a guide <NUM>, and a coil spring <NUM>. The coil spring <NUM> expands and contracts in a circumferential direction and is stored in an annular groove provided in the outer periphery of the short-circuit part <NUM>. With this structure, a contraction force is applied to the short-circuit part <NUM> in an inner periphery direction.

However, as shown in the drawing on the right in <FIG>, the short-circuit part <NUM> is divided into three portions in a circumferential direction, integrated with the insulating part <NUM> and the sliding part <NUM> into one structure, and the integrated part is supported by a guide <NUM>. The number of divisions in a circumferential direction is not limited to three, and it may be two or four or more as long as the short-circuit part <NUM> can expand and contract in a radial direction. The moving element <NUM> is composed of a rod <NUM> provided with a sliding part <NUM>.

As shown in <FIG>, starting end U1 and starting end U2, and end U3 and end U4 of the U-phase winding 150u are connected in parallel by short-circuit parts 131u1 and 131u2, respectively, thereby establishing a 2Y-connection. When the inclined surface of the protrusions of the semi-moving element sliding part <NUM> faces the inclined surface of the protrusions of the moving element sliding part <NUM>, a pressing force between the winding terminals U1 to U4 and the short-circuit part <NUM> (131u1, 131u2) is generated outward in a radial direction from the inner periphery side to the outer periphery side relative to the short-circuit part <NUM>.

Then, as shown in <FIG>, during switching, the moving element <NUM> slides in the X direction, eliminating the opposed state of the protrusions of the semi-moving element sliding part <NUM> and the protrusions of the moving element sliding part <NUM>, and the semi-moving element <NUM> contracts in an inner periphery direction by a contraction force of the coil spring <NUM>.

This movement eliminates the mechanical contact between the winding terminals U1 to U4 and the short-circuit part <NUM>. When the moving element <NUM> further slides in the X direction, as shown in <FIG>, the semi-moving element <NUM> slides in the X direction along with the moving element <NUM> while the side surface of the protrusions of the semi-moving element sliding part <NUM> and the side surface of the protrusions of the moving element sliding part <NUM> come in contact with each other. Subsequent operations are the same as those shown in <FIG>.

As stated above, in the winding switching device <NUM> according to this example, the semi-moving element short-circuit part <NUM> is divided in a circumferential direction, and the semi-moving element <NUM> is biased by a coil spring <NUM> in a radial direction of the moving element <NUM>.

Furthermore, when the protrusions of the semi-moving element sliding part <NUM> and the protrusions of the moving element sliding part <NUM> face to each other, a sufficient pressing force can be generated between the winding terminals U1 to U4 and the short-circuit part <NUM>. Thus, it is possible to suppress electrical resistance at the contact portion while avoiding the decrease in life due to sliding friction. Furthermore, since the semi-moving element <NUM> and the moving element <NUM> are made of simple cylindrical parts, unlike the link mechanism, increase of the number of parts or the size can be avoided. Thus, it is possible to provide a small winding switching device even in applications where large current will flow.

A third example of the present invention will be described with reference to <FIG>. <FIG> show the operation of the 1Y/2Y switching device for one phase according to example <NUM>. <FIG> shows the semi-moving element and the moving element of the 1Y/2Y switching device according to example <NUM>. <FIG> shows the operation of the 1Y/2Y switching device for three phases according to example <NUM>.

The winding switching device of this example is different from the winding switching device of example <NUM> (<FIG>) in the point that the semi-moving element short-circuit part <NUM> and the semi-moving element sliding part <NUM> are integrated into one metal part.

More specifically, the semi-moving element <NUM> comprises a short-circuit part 131u1 (also serves as a sliding part 133u1), a short-circuit part 131u2 (also serves as a sliding part 133u2), an insulating part 132u1, and an insulating part 132u2. The moving element <NUM> comprises sliding parts 143ula and 143ulb, sliding parts 143u2a and 143u2b, an insulating part 142u1, an insulating part 142u2, a moving element rod <NUM>, and a rod insulating part <NUM>.

As shown in <FIG>, the semi-moving element short-circuit part <NUM> is cylindrical and comprises a leaf spring 131a, slits 131b, and a sliding part <NUM> dented to the inner periphery side. By arranging a plurality of slits 131b in a circumferential direction of the cylinder, a plurality of leaf springs 131a arranged in a circumferential direction of the cylinder are capable of moving in a radial direction. Accordingly, by providing the sliding part 133a with a force to expand outward in a radial direction from the inner periphery side to the outer periphery side, the leaf springs 131a expand outward in a radial direction. On the other hand, by removing from the sliding part <NUM> the force to expand outward in a radial direction, the leaf springs 131a contract inward in a radial direction due to resilience.

As shown in <FIG>, the moving element <NUM> comprises a sliding part <NUM>, an insulating part <NUM>, a moving element rod <NUM>, and a rod insulating part <NUM>. The moving element sliding part <NUM> is cylindrical and comprises portions 143a and 143b protruding in the Z direction and a portion 143c dented in the Z direction.

That is, the semi-moving element short-circuit part <NUM> comprises at least two cylindrical conductors for each phase, and a cylindrical non-conductive member (insulating part <NUM>) is disposed between the adjacent cylindrical conductors.

The above-mentioned structure makes it possible to achieve a small winding switching device with a long life by use of simple parts. Specific operation principle will be explained in detail below.

As shown in <FIG>, starting end U1 and starting end U2, and end U3 and end U4 of the U-phase winding 150u are connected in parallel by semi-moving element short-circuit parts 131u1 and 131u2, respectively, thereby establishing a 2Y-connection. At this time, the semi-moving element sliding parts 133u1 and 133u2 and the moving element sliding parts 143ulb and 143u2b face to each other.

Then, as shown in <FIG>, during switching, the moving element <NUM> slides in the X direction, releasing the opposed state of the semi-moving element sliding parts 133u1 and 133u2 and the moving element sliding parts 143ulb and 143u2b, and the semi-moving element <NUM> slides in the Z direction.

This movement eliminates the mechanical contact between the winding terminals U1 to U4 and the short-circuit part <NUM>. When the moving element <NUM> further slides in the X direction, as shown in <FIG>, the semi-moving element <NUM> slides in the X direction along with the moving element <NUM> while the semi-moving element sliding parts 133u1 and 133u2 and the moving element sliding parts 143ulc and 143u2c come in contact with each other.

As shown in <FIG>, when the semi-moving element <NUM> reaches the stopper <NUM>, only the moving element <NUM> keeps sliding in the X direction and stops at the time the semi-moving element sliding parts 133u1 and 133u2 and the moving element sliding parts 143ula and 143u2a face to each other. By this movement, end U3 of the U-phase winding 150u1 and starting end U2 of the U-phase winding 150u2 are connected in serial by the short-circuit part 131u1, thereby establishing a 1Y-connection.

Furthermore, when the semi-moving element sliding part <NUM> and the moving element sliding part <NUM> face to each other, a sufficient pressing force can be generated between the winding terminals U1 to U4 and the short-circuit part <NUM>. Thus, it is possible to suppress electrical resistance at the contact portion while avoiding the decrease in life due to sliding friction. Furthermore, since the semi-moving element <NUM> and the moving element <NUM> are made of simple cylindrical parts, unlike the link mechanism, increase of the number of parts or the size can be avoided. Thus, it is possible to provide a small winding switching device even in applications where large current will flow.

The semi-moving element short-circuit parts 131u1 and 131u2 need to be electrically insulated from each other, and in <FIG>, insulating parts 132u1 and 132u2 are disposed therebetween in the X direction. Material for the moving element sliding part <NUM> may be metal or resin, but metal is more desirable in terms of ensuring long-time durability. However, when using metal for making a moving element sliding part <NUM>, moving element insulating parts 142u1 and 142u2 need to be provided so that electrical short-circuits will not occur between the semi-moving element short-circuit parts 131u1 and 131u2 via the moving element sliding part <NUM>.

The moving element insulating part <NUM> may be composed of a cylindrical collar, or a sheet-like insulator wrapping around the moving element rod <NUM>. When the moving element rod <NUM> is made of metal, a moving element rod insulating part <NUM> needs to be provided so as to avoid electrical short-circuits between the semi-moving element short-circuit parts 131u1 and 131u2 via the moving element rod <NUM>.

When the moving element sliding part <NUM> is made of non-conductive material such as resin, a moving element insulating part <NUM> and a moving element rod insulating part <NUM> do not necessarily have to be provided.

It is preferable that a lubricant be applied to the portion where the semi-moving element sliding part <NUM> and the moving element sliding part <NUM> mechanically come into contact with each other or be filled into a space between both sliding parts so as to reduce the friction coefficient during sliding. By doing so, actuator power can be small, resulting in achieving a further smaller winding switching device.

When using a grease as a lubrication agent, grease will adsorb abrasion powder generated at the sliding parts, so it is possible to avoid problems of a scuff at the sliding parts or electrical short-circuits caused by abrasion powder scattering in the terminals.

Thus, according to the present invention, it is possible to separate the electrical short-circuit function from the mechanically sliding function on the outer periphery side and the inner periphery side of the semi-moving element <NUM>. As a result, taking measures for achieving a long life becomes easier.

<FIG> shows the overall structure of the switching device for three phases using the winding switching device according to this example (<FIG>). The structure for each phase is the same as those in <FIG> and detailed description is omitted. In <FIG>, a 1Y-connection is established.

As shown in <FIG>, the length in the X-direction of the semi-moving element insulating part 132u2 is greater than the length in the X-direction of the insulating part 132u1 so that the V-phase semi-moving element short-circuit part 131v1 does not interfere with terminal U4 during the 1Y-connection. By integrating the moving element rod <NUM> for three phases into one structure, the number of parts can be made smaller.

A fourth example of the present invention will be described with reference to <FIG> shows a vehicle provided with a rotating machine drive system having any one of winding switching devices according to example <NUM> through example <NUM>.

The present invention applies to rotating electrical machines <NUM> and <NUM> shown in <FIG>. As shown in <FIG>, the vehicle <NUM> refers to a hybrid automobile or a plug-in hybrid automobile for example, and is provided with an engine <NUM>, rotating electrical machines <NUM> and <NUM> and a battery <NUM>.

When driving the rotating electrical machines <NUM> and <NUM>, the battery <NUM> supplies direct-current power to a power conversion device <NUM> (inverter device) for drive. The power conversion device <NUM> converts the direct-current power from the battery <NUM> to alternating-current power and supplies the alternating-current power to the rotating electrical machines <NUM> and <NUM>.

Furthermore, during regeneration traveling, the rotating electrical machines <NUM> and <NUM> generate alternating-current power according to kinetic energy of the vehicle <NUM> and supplies the alternating-current power to the power conversion device <NUM>. The power conversion device <NUM> converts the alternating-current power from the rotating electrical machines <NUM> and <NUM> to direct-current power and supplies the direct-current power to the battery <NUM>.

Rotation torque generated by the engine <NUM> and the rotating electrical machines <NUM> and <NUM> is transmitted to wheels <NUM> via a transmission <NUM>, a differential gear <NUM>, and an axle shaft <NUM>.

Generally, a wide driving range, such as low-speed high-torque for hill start, high-speed low-torque for driving on the highway, medium-speed medium-torque for driving in town, etc., is needed for automobiles. In such a wide driving range, the rotating electrical machines <NUM> and <NUM> provided with a rotating machine drive system having a winding switching device according to the present invention make highly efficient driving possible.

In addition, heat loss is reduced, making it possible to increase the safety of the vehicle <NUM> and achieving a long life. Furthermore, it becomes possible to increase the cruising distance of the vehicle <NUM>. Moreover, in an electrical automobile driven only by the power of the rotating electrical machines without having an engine <NUM>, by applying a rotating electrical machine according to the present invention, the same advantageous effects can be ensured.

Moreover, the present invention is not limited to the above-mentioned examples, since it is possible to add a structure of one example to a structure of another example.

Claim 1:
A rotating machine drive system, comprising
a rotating machine (<NUM>) having a plurality of windings (<NUM>),
an inverter device (<NUM>) for operating said rotating machine (<NUM>) at variable speed, and
a winding switching device (<NUM>) for switching connections of the plurality of windings (<NUM>), said winding switching device (<NUM>) having
winding terminals (U1, U2, U3, U4),
a semi-moving element (<NUM>) having a short-circuit part (<NUM>) facing said winding terminals (U1, U2, U3, U4) and also having a sliding part (<NUM>) provided with first protrusions on the surface opposite from the surface having said short-circuit part (<NUM>), and
a moving element (<NUM>) facing the sliding part (<NUM>) of said semi-moving element (<NUM>) and having a sliding part (<NUM>) provided with second protrusions on the surface facing the sliding part (<NUM>) of said semi-moving element (<NUM>), said moving element (<NUM>) being made to slide relative to said semi-moving element (<NUM>) so as to change the connection between said winding terminals (U1, U2, U3, U4) and said short-circuit part (<NUM>) and switch the connections of the plurality of windings (<NUM>) by bringing the winding terminals (U1, U2, U3, U4) and the short-circuit part (<NUM>) in mechanical contact or no contact dependent on the progress of sliding, wherein
the inverter device (<NUM>) comprises an inverter circuit (<NUM>) for converting direct-current power, which is output from a direct-current power source (<NUM>), to alternating-current power and outputting the alternating-current power to the rotating machine (<NUM>) through the winding switching device (<NUM>), wherein
said short-circuit part (<NUM>) comprises at least two cylindrical conductors, and a cylindrical non-conductive member is disposed between the cylindrical conductors adjacent to each other.