JP2007104789A - Power conversion system and electric vehicle equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the loss of an inverter due to increase in supply voltage or the like to fill up a deficiency in motor torque when the number of revolutions of the motor is increased and its torque becomes insufficient. <P>SOLUTION: A power conversion system includes a first power supply (100) and a second power supply (101); a first power conversion circuit (102) and a second power conversion circuit (103); a control circuit (105) that controls the first and second power conversion circuits; and a motor (104). When the number of motor revolutions is lower than a predetermined value, direct-current power from the first and second power supplies is converted into alternating-current power through the first and second power conversion circuits and it is supplied to the motor. When the number of motor revolutions is equal to or higher than the predetermined value, direct-current power arising from the series connection of the first power supply and the second power supply is converted into alternating-current power through the first power conversion circuit and it is supplied to the motor. At the same time, direct-current power arising from the series connection of the first power supply and the second power supply is converted into alternating-current power through the second power conversion circuit and it is supplied to the motor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a power conversion system and an electric vehicle having the same, and more particularly to a power conversion system in which electric motor torque is improved when the rotation speed of the electric motor is increased, and an electric vehicle having the same.

  As a conventional technique, there is a configuration related to, for example, Japanese Patent Application Laid-Open No. 2003-102181 (refer to Patent Document 1) as a first conventional technique. FIG. 5 shows the configuration of the first prior art. The DC power from the first power source 1 is converted into AC power by the inverter 3 and supplied to the motor 4. Then, a neutral point (hereinafter referred to as a midpoint) 6 of the winding of the electric motor 4 and a high potential side terminal of the second power source 2 are connected via the reactor 5. Further, the low potential side terminal of the second power source 2 and the low potential side terminal of the first power source 1 are connected. The electric motor 4 is driven by the inverter 3 and the inverter operation is adjusted to boost the low voltage of the second power source 2 by utilizing the windings of the reactor 5 and the electric motor 4. The first power supply 1 is charged with the high voltage generated thereby. The inverter 3 operates with the high voltage of the first power supply 1.

Next, as a second conventional technique, for example, there is JP-A-8-331705 (refer to Patent Document 2). In this prior art configuration, the motor has a double winding of a first winding and a second winding for each electrical phase. Then, direct current power from the fuel cell is converted into alternating current power by the first inverter and supplied to the first winding. In addition, the DC power from the secondary battery is converted into AC power by the second inverter and supplied to the second winding. That is, the configuration is such that the DC power of two different power sources of the fuel cell and the secondary battery are respectively supplied to two electrically insulated inverters and motor windings. In this way, the electric vehicle can be driven by taking out the outputs independently from the two power sources.
JP 2003-102181 (paragraphs 0015-0017, FIG. 1) JP-A-8-331705 (paragraphs 0008-0011, FIG. 1)

  However, the configuration of the first prior art has the following problems. First, the inverter 3 performs an operation of boosting the voltage of the second power source 2 as well as an operation of driving the original electric motor 4. For this reason, the loss of the inverter 3 increases. Secondly, if the voltage of the first power source 1 is boosted as necessary, when the inverter 3 output voltage is increased as required by the electric vehicle, a delay time associated with the boosting occurs. Alternatively, if the voltage of the first power supply 1 is constantly increased, the inverter 3 operates at a high voltage even when the output voltage of the inverter 3 does not need to be increased. This causes an increase in switching loss of the semiconductor element to be configured. Third, the inverter 3 needs to output a large current depending on the traveling state of the electric vehicle, and may output a high voltage. In this configuration, the first power source 1 needs to support both high current output and high voltage, and the second power source 2 that supplies power to the first power source 1 can also support high current output. Capacity is required. For this reason, the first power source 1 and the second power source 2 are increased in size and the cost is increased.

  The configuration of the second prior art has the following problems. First, the induced voltage of the motor increases as the motor speed increases as the traveling speed of the electric vehicle increases. For this reason, the electric current which can be supplied to an electric motor will reduce. In this configuration, there is no function to change the voltage supplied to the motor, and this current reduction cannot be prevented. Secondly, if either of the power supplies alone can supply the large current required by the electric vehicle, both the two power supplies need a large capacity capable of supplying the large current. As a result, the power supply is increased in size and cost. On the other hand, if the output of the two power supplies is combined to cover the large current described above, when either power supply is mainly used, the large current cannot be output. Third, even if one power supply has a large capacity capable of outputting a large current and the other power supply has a high voltage, the following problem arises. First, electric vehicles often require large currents at low speeds, such as when starting or climbing. At this time, the above-mentioned large-capacity power supply mainly supplies the necessary current. Next, when traveling at high speed, as described above, the high voltage power supply provides the necessary current. At this time, if the voltage of the large capacity power source is low, current cannot be generated. Therefore, each has two large-capacity power supplies and high-voltage power supplies that can be used for running the electric vehicle, which causes a significant increase in size and cost.

In order to solve the above-described problems, the power conversion system according to the first invention is
A first power supply, a second power supply, a first power conversion circuit, a second power conversion circuit, a control circuit for controlling the first power conversion circuit and the second power conversion circuit, and an electric motor A power conversion system comprising:
The control circuit includes:
When the rotational speed of the electric motor is lower than a predetermined value, the direct current power from the first power source is converted into alternating current power by the first power conversion circuit and supplied to the electric motor. DC power from the second power source is converted into AC power by the second power conversion circuit and supplied to the motor,
When the rotation speed of the electric motor is equal to or greater than the predetermined value, direct current power by the serial connection of the first power source and the second power source is converted into alternating current power by the first power conversion circuit. Converting and supplying the electric power to the electric motor, and converting the direct-current power by the serial connection of the first power source and the second power source into alternating current power by the second power conversion circuit to the electric motor Supply,
It is characterized by that.

The power conversion system according to the second invention is
A stator constituting the electric motor,
Each salient pole corresponding to each electrical phase has a double winding with both a first winding and a second winding, or the first winding for each electrical phase Each having a salient pole provided with a wire and a salient pole provided with the second winding,
Alternatively, the electric motor has two rotors, an inner rotor and an outer rotor, and a stator, and the stator is configured such that a part of the windings of each phase provided in the stator is a first winding. And the rest as the second winding,
The first winding is connected to the AC terminal of the first power conversion circuit corresponding to the electrical phase, and the second winding is electrically connected to the AC terminal of the second power conversion circuit. Connect to the correct phase,
It is characterized by that.

A power conversion system according to a third invention is
While the first power conversion circuit has a first inverter, the second power conversion circuit has a second inverter,
While connecting the direct current terminal of the first power conversion circuit and the direct current terminal of the first inverter, connecting the alternating current terminal of the first power conversion circuit and the alternating current terminal of the first inverter,
While connecting the DC terminal of the second power conversion circuit and the DC terminal of the second inverter, connecting the AC terminal of the second power conversion circuit and the AC terminal of the second inverter,
By connecting the low potential side terminal of the first power source and the high potential side terminal of the second power source with an inter-power source connection terminal, the first power source and the second power source are connected in series,
The high-potential side terminal of the first power source and the inter-power source connection terminal are connected to the DC terminal of the first power conversion circuit, and the inter-power source connection terminal and the low-potential side terminal of the second power source Connected to the DC terminal of the second power conversion circuit,
The first power conversion circuit is
While having a first semiconductor arm connected between the AC terminal of the first inverter and the low potential side terminal of the second power supply,
The second power conversion circuit is
A second semiconductor arm connected between the AC terminal of the second inverter and the high potential side terminal of the first power supply;
The control circuit includes:
When the rotational speed of the electric motor is equal to or greater than the predetermined value, the low side arm constituting the first inverter and the high side arm constituting the second inverter are turned off, and the first Operating the semiconductor arm and the second semiconductor arm (that is, on / off operation based on a command value such as a duty ratio);
It is characterized by that.

A power conversion system according to a fourth invention is
The low-side arm of the first inverter is configured by an anti-parallel circuit of semiconductor switch elements,
The high-side arm of the second inverter is configured by an antiparallel circuit of semiconductor switch elements,
Each of the first semiconductor arm and the second semiconductor arm is configured by connecting a diode between the AC terminal for each electrical phase and the low potential side terminal or the high potential side terminal. Configured,
The electric motor is
A third semiconductor switch between a first midpoint terminal to which the first winding of each phase is connected and a second midpoint terminal to which the second winding of each phase is connected Connect an anti-parallel circuit of the element and the third diode,
The control circuit comprises:
When the rotational speed of the electric motor is lower than the predetermined value, the third semiconductor switch element is turned off,
When the rotational speed of the electric motor is equal to or greater than the predetermined value, the semiconductor switch element constituting the low-side arm of the first inverter is turned off and the high-side arm of the second inverter To turn off the semiconductor switch element constituting, and operate the third semiconductor switch element (that is, on-off operation based on a command value such as a duty ratio),
It is characterized by that.

The power conversion system according to the fifth invention is
The low-side arm of the first inverter is configured by an anti-parallel circuit of semiconductor switch elements,
The high-side arm of the second inverter is configured by an antiparallel circuit of semiconductor switch elements,
A first semiconductor arm connected between an AC terminal of the first inverter for each electrical phase and a low potential side terminal of the second power source; It is composed of an anti-parallel circuit with 4 diodes,
A second semiconductor arm connected between an AC terminal of the second inverter for each electrical phase and a high potential side terminal of the first power supply; a fifth semiconductor switch element; Consists of an anti-parallel circuit with a fifth diode,
The control circuit comprises:
When the rotational speed of the electric motor is lower than the predetermined value, the fourth semiconductor switch element and the fifth semiconductor switch element are turned off,
When the rotational speed of the electric motor is equal to or greater than the predetermined value, the semiconductor switch element constituting the low-side arm of the first inverter is turned off and the high-side arm of the second inverter The semiconductor switch element that constitutes is turned off, and further, the fourth semiconductor switch element and the fifth semiconductor switch element are operated (on / off operation according to a duty command or the like),
It is characterized by that.

A power conversion system according to a sixth invention is
The current rating of each of the first power conversion circuit and the second power conversion circuit is smaller than the current rating of the electric motor,
The sum of the current ratings of the first power conversion circuit and the second power conversion circuit is equal to or greater than the current rating of the motor,
It is characterized by that.

The power conversion system according to the seventh invention is
When the control circuit switches the operation of the first power conversion circuit and the second power conversion circuit according to the number of revolutions of the electric motor, the low-side arm of the first inverter and the second inverter It is alternately operated between a set of the high-side arm and a set of the first semiconductor arm and the second semiconductor arm or the third switch element.
It is characterized by that.

An electric vehicle according to an eighth invention is
An electric vehicle having the power conversion system according to any one of the first to seventh aspects described above.

  As described above, the solution of the present invention has been described as an apparatus (system). However, the present invention can be realized as a method substantially equivalent to these, and these are also included in the scope of the present invention. Should be understood.

In the power conversion system according to the first aspect of the invention, the maximum output of the electric motor is often required at low speeds. For example, in a case where the power conversion system is mounted on an electric vehicle, when the maximum output of the electric motor is required, the speed is relatively low, such as when the vehicle starts or climbs a steep slope, that is, when the rotational speed is low. . On the other hand, when the vehicle speed increases, the electric motor generally requires a higher power supply voltage to supply a large current due to an increase in induced voltage. In this configuration, the following two operations and effects associated therewith are produced depending on whether the rotation speed of the electric motor is lower or higher than a predetermined value (that is, the threshold rotation speed).

  When the motor rotation speed is lower than the threshold rotation speed, the first power conversion circuit converts DC power from the first power source into AC power and supplies the AC power to the motor. The second power conversion circuit converts DC power from the second power source into AC power and supplies the AC power to the motor. Thus, a large current corresponding to a large output supplied to an electric motor mounted on a vehicle or the like can be supplied to the electric motor by connecting the first power source and the second power source in parallel. That is, since the capacity of the power supply is increased by the parallel connection, it is easy to output a large current. In addition, since the power conversion circuit performs power conversion at a relatively low voltage of each of the first power supply and the second power supply, loss associated with power conversion can be reduced. In particular, the switching loss of the semiconductor switch element constituting the power conversion circuit is significantly reduced.

  When the motor rotation speed is equal to or higher than the threshold rotation speed, the first power conversion circuit and the second power conversion circuit each convert high voltage due to the series connection of the first power supply and the second power supply into AC power. Supply to the motor. As a result, even if the induced voltage of the motor is high, the necessary current can be supplied with the high voltage of the power source. Therefore, a sufficient torque can be output at the time of high rotation. For example, when the present system is mounted on a vehicle or the like, acceleration and response such as re-acceleration during high-speed traveling can be improved. Moreover, the above effect can be realized without using a booster circuit. For this reason, there is no loss, increase in size, and cost increase due to the use of the booster circuit.

  Furthermore, in this configuration, the power source does not necessarily have to have both a large capacity and a high voltage that enable a large current output. That is, it is sufficient if a necessary capacity can be secured by parallel connection of the first power supply and the second power supply, and a necessary voltage can be secured by serial connection of the first power supply and the second power supply. Therefore, an increase in size and cost due to the provision of a large-capacity and high-voltage power supply can be avoided. In addition, although the first power source and the second power source are used, power input / output from these two power sources is approximately the same in both operations when the motor rotation speed is lower than the above-described threshold value and when it is above the threshold value. For this reason, there is no concern that power is mainly output from one power source and that the performance and life of the power source are hindered due to the imbalance between the charge and discharge states of the power source. In addition, it is not difficult to balance the charging of both power sources. The degree of charge / discharge of each of these two power sources can be adjusted by each power conversion circuit. Therefore, it is easy to balance the charge and discharge of these power sources.

Advantages of the Second Invention In the second invention, the first winding is connected to the AC terminal of the first power conversion circuit corresponding to the electrical phase, and the second winding is connected to the second power. Although the location connected to the AC terminal of the conversion circuit corresponding to the electrical phase is common, there are the following three configurations of the motor, and each produces different effects. As a first configuration of the electric motor, there is a double winding in which a first winding and a second winding are provided on each salient pole corresponding to each electrical phase. According to this configuration, since the first winding and the second winding are arranged at the same electrical angle for each phase, the operations of the first power conversion circuit and the second power conversion circuit are mutually large. It will not be different or complicated. Therefore, it is possible to easily control the operation of the electric motor. Also, by controlling the operation of both power conversion circuits, the current of both power conversion circuits can be adjusted to supply a composite current to the motor. For this reason, it is easy to increase the magnetic flux density and improve the output.

  As a second configuration of the electric motor, each electric phase includes a salient pole provided with a first winding and a salient pole provided with a second winding. According to this configuration, the output of the first power conversion circuit and the second power conversion circuit can be controlled to be a composite current, that is, not a sine wave, but the current from both circuits The magnetic flux density can be increased. Therefore, the output of the motor can be increased and the response can be improved. In particular, the salient pole of the first winding and the salient pole of the second winding are arranged at different positions, so that a composite magnetic field by this composite current can be generated more effectively. In addition, unlike the configuration in which only two power conversion circuits are used to generate a composite current, this configuration is combined with the configuration of the first invention, so that each of the first effect and this effect can be achieved simultaneously. Can occur.

Advantageous Effects of Third Invention In this configuration, when the motor rotation speed is lower than the above-described threshold rotation speed, the first inverter and the second inverter are operated to drive the motor. Thus, the electric motor can be driven via the first inverter with the first power source. Further, the electric motor can be driven via the second inverter with the second power source. Therefore, even if the first power source and the second power source are connected in series, the electric motor can be driven by the parallel power of both power sources. For this reason, the effect described in the first invention can be easily and surely produced. When the motor rotation speed is equal to or higher than the threshold rotation speed, the control circuit stops the low-side arm of the first inverter and operates the first semiconductor arm, so that the series voltage of the first power supply and the second power supply Thus, the motor can be driven by the high-side arm and the first semiconductor arm of the first inverter. Similarly, by stopping the high-side arm of the second inverter by the control circuit and operating the second semiconductor arm, the second inverter is connected with the series voltage of the first power source and the second power source. The motor can be driven by the low-side arm and the second semiconductor arm. For this reason, the effect described in the first invention can be easily and surely produced. In addition, by combining both effects, it is possible to easily and surely produce effects such as size increase, cost increase, and charge / discharge balance described in the first invention.

  In addition, according to this structure, the motor is controlled as the composite current by controlling the outputs of the first power conversion circuit and the second power conversion circuit, similarly to the effect described in the second structure of the motor in the second invention. Can supply. Therefore, the output of the inner rotor and outer rotor can be increased. Therefore, even in an electric motor having a plurality of rotors, the performance of the electric motor can be further enhanced by using the composite current. Furthermore, the effects described in the second configuration of the electric motor described above are similarly produced. In any case, since the first winding and the second winding are electrically insulated from each other, there is no concern that the output current of one power conversion circuit adversely affects the other power conversion circuit. That is, these effects can be easily and reliably exhibited without adversely affecting the electrical operation of the power conversion circuit. Moreover, even if the operating state of the power conversion circuit according to the present invention changes according to the number of revolutions of the electric motor, the effect of producing the composite current can be maintained.

According to the present configuration of the fourth aspect of the invention, it will be able to control easily operated by the control circuit, and can be easily formed by the same circuit. Further, in this configuration, these arms can be provided at a low cost, and in particular, since it is a diode, a drive circuit is not required and the cost is not increased. In this configuration, when the rotational speed of the electric motor is lower than the threshold rotational speed, the first inverter and the second inverter are electrically independent by turning off the third semiconductor switch element. Therefore, the effect described so far occurs. Here, the semiconductor switch element connected in reverse parallel to the low-side arm of the first inverter and the semiconductor switch element connected in reverse parallel to the high-side arm of the second inverter are both turned on, and the diode and What is necessary is just to make it electrically equivalent. Next, when the rotational speed of the electric motor is equal to or higher than the threshold rotational speed, the electric motor can be driven with the series voltage of the first power source and the second power source by the above-described operation by the control circuit. That is, one inverter circuit is formed on the high side of the first inverter and the low side of the second inverter, and the third switch element is connected to both sides. At this time, the diode functions as a freewheeling diode for both arms. Therefore, the various effects described above can be easily and reliably generated at a lower cost. Note that the third switch element does not require an intermittent operation unlike the switch element forming the inverter, and therefore does not cause a large switch loss.

  Further, if the first configuration of the motor described in the second invention is adopted as the electric motor, the first winding and the second winding for each phase are combined as a transformer. Therefore, in the operation when the rotation speed of the motor crosses the threshold rotation speed, even if one current of the first or second winding of each phase suddenly changes, an induced voltage is generated in the other winding. Current can continue to flow. Therefore, the electrical problem by this structure does not arise. On the other hand, even when the second to third configurations of the electric motor described in the second invention are adopted, the operation of the power conversion circuit is switched through the diode and the semiconductor switch element of each power conversion circuit without any electrical problem. be able to.

Effect of Fifth Invention By adopting this configuration, the following effects are produced. When the rotation speed of the electric motor is lower than the threshold rotation speed, the first inverter can convert the DC power of the first power source into AC power and supply it to the motor. In addition, with the second inverter, the DC power of the second power source can be converted into AC power and supplied to the motor. The semiconductor switch element connected in antiparallel which forms the low-side arm of the first inverter and the semiconductor switch element connected in antiparallel which forms the high-side arm of the second inverter are turned on to act as a diode. You can do it.

  When the rotation speed of the electric motor is equal to or higher than the threshold rotation speed, the low-side arm of the first inverter is turned off, and the first semiconductor arm is operated, so that the high-side arm of the first inverter and the first inverter With this semiconductor arm, the series voltage of the first power source and the second power source can be converted into AC power to drive the electric motor. Similarly, by turning off the high-side arm of the second inverter and operating the second semiconductor arm, the low-side arm of the second inverter and the second power supply The electric motor can be driven by converting the series voltage of the second power source into AC power. As described above, various effects described in the first and third inventions can be easily and reliably realized. Furthermore, in this configuration, even when the rotation speed of the motor is higher than the threshold rotation speed, the power conversion circuit using the high-side arm and the first semiconductor arm of the first inverter, the low-side arm and the second inverter of the second inverter Electric power can be supplied to the motor by two power conversion circuits using semiconductor arms. Therefore, when the motor rotation speed is lower than the threshold rotation speed, the current supply capability of the power conversion circuit does not decrease compared to the operation. In addition, if the configuration of the second invention is adopted in this configuration as well, the effects described in the same section are similarly produced. In particular, the AC outputs of both power change circuits are electrically insulated regardless of the rotation speed of the motor. Therefore, even when the operation state of the power conversion circuit changes, no electrical inconvenience occurs, and the above-described effects can be more reliably and easily generated.

Effects of the sixth invention By adopting this configuration, the following effects are produced. Current supply to the motor is performed by both the first power conversion circuit and the second power conversion circuit. Therefore, it is not always necessary to supply a necessary current to the electric motor in each power conversion circuit. That is, it is only necessary that the electric motor can be driven by two power conversion circuits. For this reason, an increase in cost can be suppressed without increasing the size of each power change circuit.

Effects of the seventh invention By adopting this configuration, the following effects are produced. By switching the operation of the power conversion circuit when the rotation speed of the motor crosses the above-described threshold rotation speed, the current of the motor is not suddenly changed by performing the above-described operation. That is, it is possible to easily change the current and applied voltage of the motor smoothly. Therefore, the operation of the electric motor and further the electric vehicle can be made smoother. In addition, the operation of the power conversion circuit, for example, calculation of the required current value and its execution can be performed smoothly or easily.

Effect of Eighth Invention When the power conversion system described above is mounted on a vehicle, acceleration and response such as re-acceleration when the vehicle is traveling at high speed (when the rotation speed of the motor reaches a certain high range). Can be improved. That is, it is possible to provide an electric vehicle that can appropriately respond to a driver acceleration request when the vehicle is traveling at high speed. In addition, the above-described effects can be realized without using a booster circuit that increases cost, size, or weight.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, although it demonstrates supposing the case where a power conversion system (apparatus) is mounted in an electric vehicle through the whole Example described below, it is not the intention limited to the use.
First Embodiment FIG. 1 is a schematic diagram showing the configuration. FIG. 2 is a schematic diagram showing the effect.
First, the configuration will be described. This embodiment consists of the claims 1, 3 and 4 described above. First, the configuration described in claim 1 includes a first power supply 100, a second power supply 101, a first power conversion circuit 102, a second power conversion circuit 103, and an electric motor 104. In addition, a control circuit 105 that controls the first power conversion circuit 102 and the second power conversion circuit 103 is provided. It is assumed that the electric motor 104 generates a driving force related to traveling of the electric vehicle, for example. When the rotational speed of the motor 104 is lower than a predetermined value (hereinafter referred to as a threshold rotational speed), the control circuit 105 causes the first power conversion circuit 102 to convert the DC power from the first power supply 100 into the electric power. Then, the AC power is converted into AC power and supplied to the motor 104, and DC power from the second power source 101 is converted into AC power by the second power conversion circuit 103 and supplied to the motor 104. When the rotation speed of the motor 104 is higher than the threshold rotation speed, the control circuit 105 converts the DC power from the first power supply 100 and the second power supply 101 into AC power through the first power conversion circuit 102. The first power supply 100 and the second power supply 101 are converted into AC power by the second power conversion circuit 103 and supplied to the motor 104. And

  Further, by adding the configuration of the third invention, the first power conversion circuit 102 has a first inverter 110 and the second power conversion circuit 103 has a second inverter 111. Then, a DC terminal (not shown) of the first power conversion circuit 102 and a DC terminal (not shown) of the first inverter 110 are connected, and an AC terminal 112 of the first power conversion circuit 102 and the first terminal An AC terminal (not shown) of the inverter 110 is connected. Further, a DC terminal (not shown) of the second power conversion circuit 103 and a DC terminal (not shown) of the second inverter 111 are connected, and an AC terminal 113 of the second power conversion circuit 103 and the second terminal The AC terminal (not shown) of the inverter 111 is connected. In addition, the first power supply 100 and the second power supply 101 are connected in series by connecting the low potential side terminal of the first power supply 100 and the high potential side terminal of the second power supply 101 to the inter-power supply connection terminal 106. To do. Then, the high-potential side terminal of the first power supply 100 and the inter-power source connection terminal 106 are connected to the DC terminal of the first power conversion circuit 102, and the low potential of the inter-power source connection terminal 106 and the second power source 101 The side terminal is connected to the DC terminal of the second power conversion circuit 103. In addition, the first power conversion circuit 102 includes the first semiconductor arm 120 connected between the AC terminal of the first inverter 110 and the low potential side terminal of the second power supply 101, and the second The power conversion circuit 103 includes a second semiconductor arm 121 connected between the AC terminal of the second inverter 111 and the high potential side terminal of the first power supply 100. When the rotation speed of the electric motor 104 is equal to or higher than the threshold rotation speed, the control circuit 105 causes the low-side arm 122 of the first inverter 110 and the high-side arm 123 of the second inverter 111 to be turned off, The first semiconductor arm 120 and the second semiconductor arm 121 are configured to be in operation.

  First, according to the first configuration, the present embodiment has the following effects. When the maximum output of the electric motor 104 is requested in an electric vehicle, the vehicle is relatively low in speed, such as when the vehicle starts or climbs a steep slope, that is, when the rotational speed is low. On the other hand, when the vehicle speed increases, the electric motor 104 generally requires a higher power supply voltage to supply a large current due to an increase in the induced voltage. This configuration produces the following two operations and the effects associated therewith depending on whether the rotation speed of the motor 104 is lower or higher than the threshold rotation speed.

  First, the case where the motor 104 has a lower rotation speed than the threshold rotation speed will be described. The first power conversion circuit 102 converts the DC power from the first power supply 100 into AC power and supplies the AC power to the motor 104. The second power conversion circuit 103 converts DC power from the second power source 101 into AC power and supplies the AC power to the motor 104. This produces the following effects. By connecting the first power supply 100 and the second power supply 101 in parallel, a large current corresponding to a large output supplied to the vehicle can be supplied to the electric motor 104. That is, since the capacity of the power supply is increased by the parallel connection, it is easy to output a large current. Since the power conversion circuits 102 and 103 perform power conversion at a relatively low voltage of each of the first power supply 100 and the second power supply 101, loss associated with power conversion can be reduced. In particular, the switching loss of the semiconductor switch elements constituting the power conversion circuits 102 and 103 is significantly reduced.

  Next, the case where the motor 104 speed is higher than the above threshold speed will be described. The first power conversion circuit 102 and the second power conversion circuit 103 each convert high voltage resulting from the series connection of the first power supply 100 and the second power supply 101 into AC power, and supply the AC power to the motor 104. Therefore, the following effects are produced. Even if the induced voltage of the electric motor 104 is high, the necessary current can be supplied with the high voltage of the power supplies 100 and 101. Therefore, acceleration and response such as re-acceleration during high-speed traveling can be improved. Moreover, the above effect can be realized without using a booster circuit. For this reason, there is no loss, increase in size, and increase in cost due to the use of the booster circuit. Furthermore, in this configuration, the following effects are also produced by these. Due to the effects described above, the power supply does not necessarily have to have both a large capacity and a high voltage that enable a large current output. In other words, it is sufficient if a necessary capacity can be secured by the parallel connection of the first power supply 100 and the second power supply 101, and a necessary voltage can be secured by the serial connection of the first power supply 100 and the second power supply 101. Therefore, an increase in size and cost due to the provision of a large-capacity and high-voltage power supply can be avoided. Although the first power source 100 and the second power source 101 are used, power input / output from these two power sources is approximately the same in both operations when the rotation speed of the motor 104 is lower and higher than the aforementioned threshold value. For this reason, there is no concern that power is mainly output from one of the power supplies and that the performance and life of the power supply are hindered due to the imbalance between the charge and discharge states of the power supply. In addition, it is not difficult to balance the charging of both power sources. The degree of charge / discharge of each of these two power sources can be adjusted by each power conversion circuit. Therefore, it is easy to balance the charge and discharge of these power sources. In addition to the above, since the configuration according to claim 3 is also employed, the following effects can be produced reliably and easily.

  When the motor rotation speed is lower than the above-mentioned threshold rotation speed, the first inverter 110 and the second inverter 111 are respectively operated to drive the motor 104. As a result, the motor 104 can be driven via the first inverter 110 with the first power supply 100. Further, the electric motor 104 can be driven via the second inverter 111 with the second power source 101. Therefore, even if the first power supply 100 and the second power supply 101 are connected in series, the electric motor can be driven by the parallel power of both power supplies. For this reason, the effect described in the first invention can be easily and surely produced.

  When the motor 104 rotation speed is equal to or higher than the threshold rotation speed, the control circuit 105 stops the low-side arm 122 of the first inverter 110 and operates the first semiconductor arm 120, thereby causing the first power supply 100 and the second power supply The electric motor 104 can be driven by the high-side arm of the first inverter 110 and the first semiconductor arm 120 with the series voltage of the power supply 101. Similarly, by stopping the high-side arm 123 of the second inverter 111 and operating the second semiconductor arm 121 by the control circuit 105, the series voltage of the first power supply 100 and the second power supply 101 is obtained. The electric motor 104 can be driven by the low-side arm of the second inverter 111 and the second semiconductor arm 121. For this reason, the effect described in the first invention can be easily and surely produced. In addition, by combining both the effects, the other effects described in the first invention can be easily and reliably generated.

  Further, as described at the beginning, this embodiment also adopts the configuration according to the fourth invention. This configuration consists of the following three configurations, and each configuration produces the following effects in addition to the effects described so far. First, the low-side arm of the first inverter 110 is configured by an anti-parallel circuit of semiconductor switch elements, and the high-side arm of the second inverter 123 is configured by an anti-parallel circuit of semiconductor switch elements. With this configuration, the operation can be easily controlled by the control circuit 105, and the circuit can be easily formed. Second, a diode is connected between the first semiconductor arm 120 and the second semiconductor arm 121 between the AC terminal for each electrical phase and the low potential side terminal or the high potential side terminal. It consists of. Thereby, these arms can be configured at low cost. In particular, since it is a diode, a driving circuit is unnecessary and the cost is not increased. Third, the first winding 150 and the second winding 151 are provided for each phase of the motor 104, the first midpoint terminal 130 to which the first winding of each phase is connected, and each phase A parallel circuit of the third semiconductor switch element 132 and the third diode 133 is connected between the second middle point terminal 131 to which the second winding is connected. When the rotation speed of the motor 104 is lower than the threshold rotation speed, the control circuit 105 turns off the third semiconductor switch element 132.

  On the other hand, when the rotation speed of the electric motor 104 is equal to or higher than the threshold rotation speed, the control circuit 105 turns off the semiconductor switch element forming the low-side arm 122 of the first inverter 110 and the high-side side of the second inverter 111. The semiconductor switch element forming the arm 123 is turned off, and the third semiconductor switch element 132 is turned on, that is, operated.

  This produces the following effects. First, when the rotation speed of the electric motor 104 is lower than the threshold rotation speed, the first inverter 110 and the second inverter 111 become electrically independent by turning off the third semiconductor switch element 132. Therefore, the effects described so far are produced. Here, both the semiconductor switch element connected in reverse parallel to the low side arm 122 of the first inverter 110 and the semiconductor switch element connected in reverse parallel to the high side arm 123 of the second inverter 111 are turned on. In other words, it may be electrically equivalent to the diode. Next, when the rotation speed of the electric motor 104 is equal to or higher than the threshold rotation speed, the electric motor 104 can be driven with the series voltage of the first power supply 100 and the second power supply 101 by the above-described operation by the control circuit 105. That is, the high-side arm of the first inverter 110 and the low-side arm of the second inverter 111 form one inverter circuit, and the third switch element 132 is connected to both the side arms. At this time, the three diodes constituting the first semiconductor arm 120 function as free-wheeling diodes for both side arms. Therefore, the various effects described above can be easily and reliably generated at a lower cost. Note that the third switch element 132 does not require an intermittent operation unlike the switch element forming the inverter, and therefore does not cause a large switch loss.

  Furthermore, if the electric motor has a configuration in which the first winding 150 and the second winding 151 are wound around the same salient pole for each electrical phase, the first winding and the second winding for each phase are provided. It becomes a combined form as a transformer. Therefore, even when the current of one of the first winding 150 or the second winding 151 of each phase suddenly changes in the operation when the rotation speed of the motor crosses the threshold rotation speed, An induced voltage is generated and current can continue to flow. Therefore, the electrical problem by this structure does not arise.

  As described above, the present embodiment can exhibit the characteristics shown in FIG. That is, as the rotational speed of the motor increases, the current decreases due to the induced voltage increase of the motor, and the torque gradually decreases. When this rotational speed exceeds the above-mentioned threshold value, in this embodiment, the voltage that can be applied to the electric motor can be increased, so that a decrease in current can be prevented. This threshold is used as an operation switching point A in this configuration, and electric power is supplied to the electric motor via different paths with this point A as a boundary. Therefore, the torque can be increased in a region where the rotational speed of the motor is high as compared with the case where the present embodiment shown by the broken line in FIG.

Second Embodiment FIG. 3 is a schematic diagram showing a configuration according to the second embodiment. FIG. 4 is a schematic diagram showing the effect. First, the configuration will be described. The present embodiment is composed of the configurations described in the first, third and fifth inventions. Here, the configurations according to the first and third inventions and the resulting effects are the same as those described in the first embodiment. At that time, as each component, the first power conversion circuit is replaced with 102 to 202, the first inverter is replaced with 110 to 210, the first semiconductor arm is replaced with 120 to 220, and the AC terminal 112 is replaced with 212. Further, the second power conversion circuit 103 is replaced with 203, the second inverter is replaced with 111 to 211, the second semiconductor arm is replaced with 121 to 221 and the AC terminal 113 is replaced with 213. Further, the low side arm 122 is replaced with 222, the high side arm 123 is replaced with 223, and the electric motor 104 is replaced with 204. At the same time, the first winding 150 is replaced with 250, and the second winding 151 is replaced with 251. Also, a first midpoint terminal 230 to which the first winding of each phase is connected and a second midpoint terminal 231 to which the second winding of each phase is connected are provided.

  Further, the second embodiment also adopts the configuration described in the fifth invention as described above. This also produces the following effects. First, the configuration will be described. The low-side arm 222 of the first inverter 210 is configured by an anti-parallel circuit of semiconductor switch elements, and the high-side arm 223 of the second inverter 211 is configured by an anti-parallel circuit of semiconductor switch elements. Then, as the first semiconductor arm 220, the reverse of the fourth semiconductor switch element and the fourth diode connected between the AC terminal and the low potential side terminal of the first inverter 210 for each electrical phase. It has a parallel circuit. As the second semiconductor arm 221, a parallel circuit of a fifth semiconductor switching element and a fifth diode connected between the AC terminal and the high potential side terminal of the second inverter 211 for each electrical phase. Have Further, when the rotation speed of the electric motor 204 is lower than the threshold rotation speed, the control circuit 105 turns off the fourth semiconductor switch element and the fifth semiconductor switch element. Further, when the rotation speed of the electric motor 204 is equal to or higher than the threshold rotation speed, the control circuit 105 turns off the semiconductor switch element that forms the low-side arm 222 of the first inverter 210 and the high-side of the second inverter 211. The semiconductor switch element forming the side arm 223 is turned off, and the fourth semiconductor switch element and the fifth semiconductor switch element are further operated. With this configuration, the following effects are produced.

When the rotation speed of the electric motor 204 is lower than the threshold rotation speed, in this case, the first inverter 210 can convert the DC power of the first power supply 100 into AC power and supply it to the motor 204. In addition, the second inverter 211 can convert the DC power of the second power source 101 into AC power and supply it to the electric motor 204. The semiconductor switch elements connected in antiparallel constituting the low side arm 222 of the first inverter 210 and the semiconductor switch elements connected in antiparallel constituting the high side arm 223 of the second inverter 211 are ON. It is sufficient to make it act like a diode.

In this case , when the rotational speed of the electric motor 204 is equal to or higher than the threshold rotational speed , the low-side arm 222 of the first inverter 210 is turned off and the first semiconductor arm 220 is operated so that the high-side of the first inverter 210 By using the side arm and the first semiconductor arm 220, the series voltage of the first power supply 100 and the second power supply 101 can be converted into AC power to drive the electric motor 204. Similarly, by turning off the high-side arm 223 of the second inverter 211 and operating the second semiconductor arm 221 (that is, on / off operation), the low-side arm of the second inverter 211 and the second inverter 211 The semiconductor arm 221 can drive the electric motor 204 by converting the series voltage of the first power supply 100 and the second power supply 101 into AC power. As described above, the various effects described in the first and third inventions can be easily and reliably realized.

  Therefore, in this configuration, the characteristics shown in FIG. 4 can be obtained. Even when the operation switching point A is exceeded, that is, when the rotation speed of the electric motor 204 is equal to or higher than the threshold rotation speed, the power conversion circuit including the high-side arm of the first inverter 210 and the first semiconductor arm 220, and the second inverter Electric power can be supplied to the electric motor 204 by two power conversion circuits including the low-side arm 211 and the second semiconductor arm 221. For this reason, the current supply capability of the power conversion circuit does not decrease when compared with the operation when the motor 204 has a lower rotational speed than the threshold rotational speed. That is, even if the rotation speed of the motor increases and the induced voltage of the motor increases, if the operation is switched before the torque gradually decreases, the voltage that can be applied to the motor can be increased to prevent a decrease in current. Therefore, the torque can be increased in a region where the rotational speed of the motor is high as compared with the case where the present embodiment shown by the broken line in FIG.

  Here, in each of the first embodiment and the second embodiment, if the configuration according to the second invention is also employed, the following effects are additionally produced in addition to the effects of the respective embodiments. By adopting the following three configurations for the above-described electric motor, the following effects are produced. In the following description, the electric motor indicates 104 or 204, the first winding indicates 150 or 250, and the second winding indicates 151 or 251. As a first configuration of the electric motor, there is a double winding in which a first winding and a second winding are provided on each salient pole corresponding to each electrical phase. And the first winding is connected to the AC terminal of the first power conversion circuit corresponding to the electrical phase, and the second winding is connected to the AC terminal of the second power conversion circuit in the electrical phase. Connect accordingly. This produces the following effects. Since the first winding and the second winding are arranged at the same electrical angle for each phase, the operations of the first power conversion circuit and the second power conversion circuit are greatly different from each other or complicated. Never become. Therefore, it is possible to easily control the operation of the electric motor. Also, by controlling the operation of both power conversion circuits, the current of both power conversion circuits can be adjusted to supply a composite current to the motor. For this reason, it is easy to increase the magnetic flux density and improve the output.

  As a second configuration of the electric motor, each electric phase includes a salient pole provided with a first winding and a salient pole provided with a second winding. And the first winding is connected to the AC terminal of the first power conversion circuit corresponding to the electrical phase, and the second winding is connected to the AC terminal of the second power conversion circuit in the electrical phase. Connect accordingly. This produces the following effects. The outputs of the first power conversion circuit and the second power conversion circuit can be controlled to form a composite current, that is, not a simple sine wave, but the current from both circuits can be combined to increase the magnetic flux density inside the motor. Therefore, the output of the motor can be increased and the response can be improved. In particular, the salient pole of the first winding and the salient pole of the second winding are arranged at different positions, so that a composite magnetic field by this composite current can be generated more effectively. In addition, in order to generate a composite current, unlike the configuration using only two power conversion circuits, by adopting this configuration in combination with the configuration of the first invention, each effect of the first invention and this effect can be achieved. Can occur simultaneously.

  As a third configuration of the electric motor, the electric motor has two rotors, an inner rotor and an outer rotor, and among the windings of each phase provided in the stator portion, half the winding is the first winding, Half as a second winding. Then, the first winding is connected to the AC terminal of the first power conversion circuit corresponding to the electrical phase, and the second winding is electrically connected to the AC terminal of the second power conversion circuit. Connect according to the phase. This produces the following effects. Similar to the effect described in the second configuration of the electric motor described above, the outputs of the first power conversion circuit and the second power conversion circuit can be controlled and supplied to the electric motor as a composite current. Therefore, the output of the inner rotor and outer rotor can be increased. Therefore, even in an electric motor having a plurality of rotors, the performance of the electric motor can be further enhanced by using the composite current. Further, the effect described in the second configuration of the electric motor is similarly generated. In any case, since the first winding and the second winding are electrically insulated from each other, there is no concern that the output current of one power conversion circuit adversely affects the other power conversion circuit. That is, these effects can be easily and reliably exhibited without adversely affecting the electrical operation of the power conversion circuit. Moreover, even if the operating state of the power conversion circuit according to the present invention changes according to the number of revolutions of the electric motor, the effect of producing the composite current can be maintained. In particular, in the configuration of the second embodiment, the AC outputs of both power change circuits are electrically insulated regardless of the rotation speed of the electric motor. Therefore, even when the operating state of the power conversion circuit changes, no electrical inconvenience occurs, and the above-described effects can be more reliably and easily generated.

  Furthermore, in both the first embodiment and the second embodiment, if the configurations according to the sixth and seventh inventions are also employed, the following effects are additionally produced. First, in the configuration described in the sixth invention, the current ratings of the first power conversion circuit and the second power conversion circuit are smaller than the current rating of the electric motor. The sum of the current ratings of the first power conversion circuit and the second power conversion circuit is the same as or greater than the current rating of the motor. By adopting such a configuration, the following effects are produced. Current supply to the motor is performed by both the first power conversion circuit and the second power conversion circuit. Therefore, it is not always necessary to supply a necessary current to the motor by each power conversion circuit. That is, it is only necessary that the electric motor can be driven by two power conversion circuits. For this reason, an increase in cost can be suppressed without increasing the size of each power change circuit.

  Next, as a configuration described in the seventh invention, when the control circuit switches the operation of the first power conversion circuit and the second power conversion circuit according to the rotation speed of the electric motor, The high inverter side of the two inverters, the first semiconductor arm and the second semiconductor arm, and the third switch element are configured to operate intermittently. With this configuration, the following effects are produced. By switching the operation of the power conversion circuit when the rotation speed of the motor crosses the above-described threshold rotation speed, the current of the motor is not suddenly changed by performing the above-described operation. That is, it is possible to easily change the current and applied voltage of the motor smoothly. Therefore, the operation of the electric motor and further the electric vehicle can be made smoother. In addition, the operation of the power conversion circuit, for example, calculation of the required current value and its execution can be performed smoothly or easily.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions and the like included in each member and each circuit can be rearranged so as not to be logically contradictory, and a plurality of members and circuits can be combined into one or divided.

FIG. 3 is a diagram showing a configuration of a first example. FIG. 6 is a schematic diagram showing the effect of the first embodiment. FIG. 6 is a diagram showing a configuration of a second example. FIG. 10 is a schematic diagram showing the effect of the second embodiment. It is a figure which shows a conventional structure.

Explanation of symbols

1 First power supply
2 Second power supply
3 Inverter
4 Electric motor
5 Reactor
100 First power supply
101 Second power supply
102 First power conversion circuit
103 Second power conversion circuit
104 electric motor
105 Control circuit
106 Power supply terminal
110 First inverter
111 Second inverter
112 AC terminal
113 AC terminal
120 First semiconductor arm
121 Second semiconductor arm
122 First inverter low-side arm
123 High-side arm of second inverter 210
130 1st midpoint terminal
131 Second midpoint terminal
132 Third semiconductor switch element
133 Third diode
150 First winding
151 Second winding
202 First power conversion circuit
203 Second power conversion circuit
204 electric motor
210 First inverter
211 Second inverter
212,213,214,215 AC terminal
220 First semiconductor arm
221 Second semiconductor arm
222 Low-side arm of the first inverter
223 High-side arm of second inverter
230 1st midpoint terminal
231 Second midpoint terminal
250 1st winding
251 Second winding

Claims (8)

A first power supply, a second power supply, a first power conversion circuit, a second power conversion circuit, a control circuit for controlling the first power conversion circuit and the second power conversion circuit, and an electric motor A power conversion system comprising:
The control circuit comprises:
When the rotational speed of the electric motor is lower than a predetermined value, the direct current power from the first power source is converted into alternating current power by the first power conversion circuit and supplied to the electric motor. DC power from a second power source is converted to AC power by the second power conversion circuit and supplied to the motor,
When the rotation speed of the electric motor is equal to or greater than the predetermined value, direct current power by the serial connection of the first power source and the second power source is converted into alternating current power by the first power conversion circuit. Converting and supplying the electric power to the electric motor, and converting the direct-current power by the serial connection of the first power source and the second power source into alternating current power by the second power conversion circuit to the electric motor Supply,
A power conversion system characterized by that. The power conversion system according to claim 1,
A stator constituting the electric motor,
Each salient pole corresponding to each electrical phase has a double winding with both a first winding and a second winding, or the first winding for each electrical phase Each having a salient pole provided with a wire and a salient pole provided with the second winding,
Alternatively, the electric motor has two rotors, an inner rotor and an outer rotor, and a stator, and the stator is configured such that a part of the windings of each phase provided in the stator is a first winding. And the rest as the second winding,
The first winding is connected to the AC terminal of the first power conversion circuit corresponding to the electrical phase, and the second winding is electrically connected to the AC terminal of the second power conversion circuit. Connect to the correct phase,
A power conversion system characterized by that. The power conversion system according to claim 1 or 2,
While the first power conversion circuit has a first inverter, the second power conversion circuit has a second inverter,
While connecting the direct current terminal of the first power conversion circuit and the direct current terminal of the first inverter, connecting the alternating current terminal of the first power conversion circuit and the alternating current terminal of the first inverter,
While connecting the DC terminal of the second power conversion circuit and the DC terminal of the second inverter, connecting the AC terminal of the second power conversion circuit and the AC terminal of the second inverter,
By connecting the low potential side terminal of the first power source and the high potential side terminal of the second power source with an inter-power source connection terminal, the first power source and the second power source are connected in series,
The high-potential side terminal of the first power source and the inter-power source connection terminal are connected to the DC terminal of the first power conversion circuit, and the inter-power source connection terminal and the low-potential side terminal of the second power source Connected to the DC terminal of the second power conversion circuit,
The first power conversion circuit is
While having a first semiconductor arm connected between the AC terminal of the first inverter and the low potential side terminal of the second power supply,
The second power conversion circuit is
A second semiconductor arm connected between the AC terminal of the second inverter and the high potential side terminal of the first power supply;
The control circuit includes:
When the rotational speed of the electric motor is equal to or greater than the predetermined value, the low side arm constituting the first inverter and the high side arm constituting the second inverter are turned off, and the first Operating a semiconductor arm and the second semiconductor arm;
A power conversion system characterized by that. The power conversion system according to claim 3, wherein
The low-side arm of the first inverter is configured by an anti-parallel circuit of semiconductor switch elements,
The high-side arm of the second inverter is configured by an antiparallel circuit of semiconductor switch elements,
Each of the first semiconductor arm and the second semiconductor arm is configured by connecting a diode between the AC terminal for each electrical phase and the low potential side terminal or the high potential side terminal. Configured,
The electric motor is
A third semiconductor switch between a first midpoint terminal to which the first winding of each phase is connected and a second midpoint terminal to which the second winding of each phase is connected Connect an anti-parallel circuit of the element and the third diode,
The control circuit comprises:
When the rotational speed of the electric motor is lower than the predetermined value, the third semiconductor switch element is turned off,
When the rotational speed of the electric motor is equal to or greater than the predetermined value, the semiconductor switch element constituting the low-side arm of the first inverter is turned off and the high-side arm of the second inverter Turning off the semiconductor switch element that constitutes, and operating the third semiconductor switch element,
A power conversion system characterized by that. The power conversion system according to claim 3, wherein
The low-side arm of the first inverter is configured by an anti-parallel circuit of semiconductor switch elements,
The high-side arm of the second inverter is configured by an antiparallel circuit of semiconductor switch elements,
A first semiconductor arm connected between an AC terminal of the first inverter for each electrical phase and a low potential side terminal of the second power source; It is composed of an anti-parallel circuit with 4 diodes,
A second semiconductor arm connected between an AC terminal of the second inverter for each electrical phase and a high potential side terminal of the first power supply; a fifth semiconductor switch element; Consists of an anti-parallel circuit with a fifth diode,
The control circuit comprises:
When the rotational speed of the electric motor is lower than the predetermined value, the fourth semiconductor switch element and the fifth semiconductor switch element are turned off,
When the rotational speed of the electric motor is equal to or greater than the predetermined value, the semiconductor switch element constituting the low-side arm of the first inverter is turned off and the high-side arm of the second inverter Turning off the semiconductor switch element constituting, further operating the fourth semiconductor switch element and the fifth semiconductor switch element,
A power conversion system characterized by that. In the power conversion system according to any one of claims 1 to 5,
The current rating of each of the first power conversion circuit and the second power conversion circuit is smaller than the current rating of the electric motor,
The sum of the current ratings of the first power conversion circuit and the second power conversion circuit is equal to or greater than the current rating of the motor,
A power conversion system characterized by that. In the power conversion system according to any one of claims 4 to 6,
When the control circuit switches the operation of the first power conversion circuit and the second power conversion circuit according to the number of revolutions of the electric motor, the low-side arm of the first inverter and the second inverter It is alternately operated between a set of the high-side arm and a set of the first semiconductor arm and the second semiconductor arm or the third switch element.
A power conversion system characterized by that.   An electric vehicle having the power conversion system according to claim 1.

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