JP3612572B2 - Motor drive power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor drive power supply device, and more particularly to a power supply device suitable for driving a power motor such as an electric vehicle, an electric scooter, and an electric bicycle.
[0002]
[Prior art]
As a power supply device for driving a power motor for electric vehicles, electric scooters, and electric bicycles, there is a hybrid power supply device in which a battery and a capacitor are connected in parallel and an output from this parallel circuit is supplied to the motor via a power converter. Many proposals have been made. In this case, the capacitor functions to supply a large amount of power to the motor in a short time according to the load fluctuation of the motor, and the battery functions to supply the average power to the motor for a long time with a small amount of power. This is to reduce the peak load on the battery, extend the battery life, and substantially increase the capacity.
[0003]
An example of such a conventional motor driving power supply is shown in FIG. A plurality of battery groups 10 connected in series to generate a high voltage and a plurality of capacitor groups 12 connected in series have a common potential on the minus (−) side and current control on the plus (+) side. They are connected in parallel via the circuit 14. The current control circuit 14 is for preventing an overcurrent from flowing from the battery group 10, and the voltage from the parallel circuit of the battery group 10 and the capacitor group 12 is a power converter that is a motor drive circuit. 16 and supplied to both ends of the DC motor 18. The power converter 16 is a chopper or an inverter, and its operation is controlled by a control circuit (not shown).
[0004]
An example of using a chopper for the power converter 16 is shown in FIG. The input / output terminals 40 and 42 correspond to the two left terminals of the power converter 16, and the input / output terminals 54 and 56 correspond to the two right terminals of the power converter 16. Between terminals 40 and 42, drains and sources (or collectors and emitters) of transistors 44 and 46 such as a power transistor, an insulated gate transistor (IGBT), and a field effect transistor (FET) are connected in series as shown in the figure. The gates (or bases) of these transistors receive a control pulse signal from the control circuit. Between the collector and emitter (or between the drain and source) of the transistors 44 and 46, diodes 48 and 50 are connected in opposite polarities, respectively, and a common connection point of these diodes 48 and 50 is connected via a choke coil 52 to a terminal. 54. In addition, an electrolytic capacitor 41 is connected between the terminals 40 and 42 in order to stabilize the voltage fluctuation of the power supply caused by the operation of the transistor as a switching element.
[0005]
During powering to drive the motor 18 to rotate, the transistor 46 in the power converter 16 is always non-conductive, and the transistor 44 repeats conduction and non-conduction in response to a control pulse signal from the control circuit. Therefore, the power converter 16 steps down the voltage from the parallel circuit of the battery group 10 and the capacitor group 12 according to the time ratio of conduction and non-conduction of the control pulse signal, that is, the shock coefficient, and supplies the voltage to the motor 18. . Further, at the time of regeneration in which the supply of drive voltage to the motor 18 is stopped, the motor 18 functions as a generator. During this time, the transistor 44 in the power converter 16 is always controlled to be non-conductive by the control circuit, and the transistor 46 is repeatedly conductive and non-conductive according to the control pulse signal from the control circuit. Therefore, the power converter 16 boosts the voltage (regenerative voltage) generated by the motor 18 to charge (accumulate) the capacitor group 12. The energy charged in the capacitor group 12 is reused during powering of the motor to improve the efficiency of the entire power supply device. Further, during power running, the rotational speed of the motor, torque, and the like can be controlled by controlling the degree of step-down of the power converter 16 according to the impact coefficient of the control pulse signal.
[0006]
Another example of a conventional motor driving power supply is shown in FIG. The difference from the prior art of FIG. 2 is that the positive side of the battery group 10 and the capacitor group 12 is alternately selected at high speed by the semiconductor switch 20 and the selected voltage is supplied to the power converter 16. . The semiconductor switch 20 can be a power transistor, an insulated gate transistor (IGBT), a field effect transistor (FET), or the like, and the switch control circuit 22 controls high-speed switching of the switch 20. As in the case of FIG. 2, the power converter 16 steps down the output voltage of the switch 20 and supplies it to the motor 18 when the motor 18 is powered. Further, during regeneration of the motor 18, the power converter 16 boosts the generated voltage of the motor 18 and charges the capacitor group 12 via the switch 20. This charged energy (power storage energy) is reused during powering of the motor, as in the prior art of FIG.
[0007]
By the way, in order to obtain electric power for driving the motor from the capacitor, the capacitor must have a large capacity. However, even with a large-capacity capacitor, the charging energy of the capacitor is one digit or more smaller than that of the battery, so it is necessary to effectively use the energy stored in the capacitor. Using all the energy stored in the capacitor means using it until the voltage on the capacitor reaches zero. However, in the prior art shown in FIGS. 2 and 4, the motor 18 is driven by the power converter 16 also using the voltage of the capacitor 12, but this drive requires a voltage of a certain level or more. Therefore, before the voltage of the capacitor 12 becomes zero, the power converter 16 and the motor 18 do not operate, so that the stored energy of the capacitor 12 cannot be used up. This is the same even if a booster circuit is provided at the terminal of the capacitor 12, and the stored energy of the capacitor 12 cannot be used up.
[0008]
The mainstream of large-capacity capacitors is an electric double layer capacitor, but this capacitor can only have a voltage per cell of about 1 to 5 volts in order to prevent electrolysis of the electrolyte. Therefore, in order to drive the motor, it is necessary to increase the voltage required by the motor, and thus a plurality of electric double layer capacitors must be connected in series. However, there arises a problem of voltage balance in each capacitor. This problem is caused by the fact that the capacitors self-discharge due to the internal resistance after all the capacitors connected in series are charged, and the variation in self-discharge is very large. For this reason, with the passage of time, the voltage of a certain capacitor becomes zero volts. In this state, when discharged, the zero-volt capacitor cannot keep the lower limit, and when charged, another capacitor cannot keep the upper limit, and charging and discharging cannot be performed.
[0009]
Therefore, in order to solve the above problem that the stored energy of the capacitor cannot be used and the problem when a plurality of capacitors are connected in series, Japanese Patent Application No. 7-174743 discloses a motor driving power source shown in FIG. A device was proposed. In this power supply device, when the motor 18 is powered, the first power converter 28 steps down the voltage of the series circuit of the battery 26 and the capacitor 24 and supplies the drive voltage to the motor 18. Further, during regeneration of the motor 18, the second power converter 32 receives the power generation voltage from the motor 18 to step down and supplies a charging voltage to the capacitor 24. The step-down operation of the power converters 28 and 32 is controlled by a control pulse signal from the control circuit 34. In addition, polarity inversion preventing diodes 36 are connected to both ends of the capacitor 24. When the discharge of the capacitor 24 progresses during the power running of the motor 18, the charging voltage decreases. Finally, the polarity is reversed when the charged amount becomes zero, but this diode 36 becomes conductive when the polarity of the capacitor 24 is reversed. Thus, this polarity reversal is prevented. However, during the period in which the polarity of the capacitor 24 is not reversed, the diode 36 is non-conductive, and thus does not affect the operation of the power supply device.
[0010]
According to the motor drive power supply device shown in FIG. 5, since the capacitor 24 and the battery group 26 are connected in series, even if the stored voltage of the capacitor 24 is lowered, the voltage of the entire series circuit is the power converter 28 and It is high enough to drive the motor 18 and can be used until the energy stored in the capacitor 24 becomes completely zero when the motor 18 is powered. Further, the voltage of the capacitor 24 does not need to be as high as the voltage of the battery group 26 and may be low, so that it is not necessary to connect a large number of capacitors in series. Therefore, the problem of capacitor voltage balance is reduced, and a large-capacitance capacitor can be used with a low voltage specification. Therefore, an inexpensive electric double layer capacitor can be used as the capacitor 24.
[0011]
Unlike the power converter 16 in FIGS. 2 and 4, the first power converter 28 and the second power converter 32 perform power conversion by unidirectional step-down. Each of the first and second power converters is one of a chopper circuit and a DC / DC converter, or the first power converter is an inverter and the second power converter is an AC / DC inverter. As an example, the case of a chopper is shown in FIG. In FIG. 6, a transistor 62 similar to the above-described transistor 44 or 46 and a series circuit of a choke coil 66 are connected between an input terminal 58 and an output terminal 68, and a common connection point between the transistor 62 and the coil 66 is connected. A diode 64 is connected between the input terminal 60 and the output terminal 70. The gate (or base) of the transistor 62 is controlled by a control pulse signal from the control circuit 34 so that the transistor 62 is alternately turned on and off, and the input terminals 58 and 60 are connected according to the shock coefficient of the control pulse signal. Is reduced and output between the output terminals 68 and 70. Note that an electrolytic capacitor 59 is connected between the terminals 58 and 59 in order to stabilize the voltage fluctuation of the power supply caused by the operation of the transistor as a switching element.
[0012]
[Problems to be solved by the present invention]
By the way, power motors for electric vehicles, electric scooters, electric bicycles, and the like, and their power converters are designed and fully adjusted (matched or tuned) in advance so that they perform best when they are combined. Some are on the market. If such a commercially available combination is used, the highest performance can be obtained without the need for redesign and readjustment. When this commercially available combination is applied to the power supply device shown in FIG. 5, the combined power converter is used as the first power converter 28. However, since the second power converter 32 is connected to the common connection point between the motor 18 and the first power converter 28, the presence of the second power converter 32 causes the motor 18 and the first power set in advance to be set. 1 Matching of the power converter 28 is broken, and it cannot be operated at the highest performance. Therefore, in order to achieve the highest performance in the power supply device of FIG. 5, the first and second power converters are considered in consideration of the combination of the first power converter 28, the second power converter 32, and the motor 18. New designs and adjustments must be made, and commercially available combinations cannot be used as they are. Due to the new design and adjustment, the entire power supply device becomes expensive and new developments are prolonged.
[0013]
5, the capacitor 24 cannot be charged by the battery group 26 via the first power converter 28 and the second power converter 32 while the motor 18 is stopped. This is because the battery group 26 will be short-circuited if the first and second power converters 28 and 32 are operated simultaneously. On the other hand, if the capacitor 24 of the motor drive power supply device is fully charged before the start of the electric vehicle or the like, that is, when the motor 18 is stopped, it is possible to prepare for acceleration of the electric vehicle or the like. It is.
[0014]
Therefore, the object of the present invention is that not only can the stored energy of the capacitor be completely zero during powering of the motor, but also a large-capacity capacitor can be used with a low voltage specification, and a commercially available optimally matched in advance. It is an object of the present invention to provide a motor driving power supply device that can use a combination of a motor and a power converter as it is.
[0015]
Another object of the present invention is to provide a motor drive power supply device that can charge a capacitor even when the motor is stopped.
[0016]
[Means for Solving the Problems]
In the motor drive power supply device of the present invention, a battery 26 and a capacitor 24 are connected in series; a first input / output terminal is connected to both ends of the series circuit via a switch circuit 72, and a second input / output terminal is connected to the motor 18. The input end is coupled to the common connection point of the switch circuit 72 and the first power converter 16, and the output end is coupled to the common connection point of the battery 26 and the capacitor 24 of the series circuit. A second power converter 32; and a control circuit 73 for controlling the opening and closing of the switch circuit 72. The first input / output terminal is electrically connected directly to the switch circuit 72; When the motor 18 is powered, the control circuit 73 closes the switch circuit 72. Keep the continuity , Power from the series circuit via the switch circuit 72 and the first power converter 16 Motor 18 To supply. Further, at the time of regeneration of the motor 18, the control circuit 73 opens the switch circuit 72 (non-conducting), and the generated voltage (regenerative voltage) of the motor 18 passes through the first power converter 16 and the second power converter 32. To charge the capacitor 24. The control circuit 73 controls the second power converter 32 to stop its operation when the motor 18 is powered, and controls the switch circuit 72 and the second power converter 32 during the stop period of the motor 18. Thus, the capacitor 24 can be charged by the battery 26.
[0017]
The first power converter 16 is a chopper circuit or an inverter circuit that performs a step-down operation from the series circuit in the direction of the motor 18 and performs a step-up operation or a rectification operation in the direction from the motor 18 to the series circuit. The device 32 is a chopper circuit or a DC / DC converter circuit that performs a step-down operation from the first power converter toward the capacitor 24.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a block diagram of a preferred embodiment of a motor drive power supply device of the present invention. For example, one electric double layer capacitor 24 that is a general large-capacity capacitor and a plurality of batteries 26 that are storage batteries, for example, are connected in series to form a series circuit. The opposite end (plus end) of the capacitor 24 of the battery group 26 of this series circuit is coupled to one (upper side) of the left input / output end of the first power converter 16 via the semiconductor switch circuit 72. The negative end of the first power converter 16 is coupled to the other (lower side) of the left input / output end of the first power converter 16. The switch element of the switch circuit 72 is, for example, a relay, a contactor, a power transistor, an insulated gate transistor (IGBT), or a field effect transistor (FET). The opening / closing of the switch circuit 72 is controlled by a control signal from the control circuit 73. The second power converter 32 is inserted between the common connection point of the capacitor 24 and the battery group 26 and the common connection point of the first power converter 16 and the switch circuit 72. Further, a bypass diode 36 for preventing polarity reversal is coupled to both ends of the capacitor 24. The motor 30 is coupled between a pair of input / output terminals on the right side of the first power converter 16. The control circuit 73 also controls the operations of the power converters 16 and 32. Since no other circuit, for example, the second power converter 32 is connected between the connection of the first power converter 16 and the motor 18, the optimal optimum set in advance for the first power converter 16 and the motor 18 is not connected. It should be noted that combinations can be used as they are without breaking the matching.
[0019]
The first power converter 16 steps down the voltage from the capacitor 24 and the battery group 26 and supplies the voltage to the motor 18 when the motor 18 is powered, and also generates the generated voltage (regenerative voltage) of the motor 18 when the motor 18 is regenerated. A bidirectional chopper or inverter that boosts or rectifies and supplies it to the second power converter 32. When the first power converter 16 is a chopper, the circuit shown in FIG. 3 can be used. In this case, the terminal 40 is connected to the common connection point of the switch circuit 72 and the second power converter 32, the terminal 42 is connected to the negative end of the capacitor 24, and the motor 18 is connected between the terminals 54 and 56. The gates (or emitters) of the transistors 44 and 46 receive a control pulse signal from the control circuit 73.
[0020]
The second power converter 32 is a unidirectional chopper or DC / DC converter that steps down the power generation voltage of the motor 18 and supplies it to the capacitor 24 via the first power converter 16 during regeneration of the motor 18. is there. When the second power converter 32 is a chopper, the circuit shown in FIG. 6 can be used. In this case, the terminal 58 is connected to the common connection point of the switch circuit 72 and the first power converter 16, the terminal 68 is connected to the positive end of the capacitor 24, and the terminals 60 and 70 are the reference potential, for example, the negative of the capacitor 24. Connected to the end. The gate (or emitter) of the transistor 62 receives a control pulse signal from the control circuit 73.
[0021]
The operating power of the first power converter 16, the second power converter 32, and the control circuit 73 may be obtained directly from the battery 26 or the series circuit of the battery 26 and the capacitor 24, or the output of the battery 26 or the series circuit may be obtained. It may be obtained via a DC / DC converter. Further, an auxiliary power source different from the battery 26 may be provided and obtained from there. Furthermore, it may be obtained from the power running power of the first power converter 16 or may be obtained from the regenerative power of the second power converter 32. When the first power converter 16 is a chopper or an inverter, if the power supply voltage for the chopper or inverter is higher than the electromotive force of the motor 18, the switching element (transistor) is turned on and off. By adjusting the time ratio (impact coefficient), regenerative power control at boosting is possible. However, when the power supply voltage is lower than the electromotive force of the motor 18, the chopper or the inverter simply acts as a rectifier and the regenerative power cannot be controlled. However, the second power converter 32 controls the regenerative power. There is no problem because the capacitor 24 can be charged.
[0022]
When the motor drive power supply device of the present invention is used in an electric vehicle, the control circuit 73 controls conduction / non-conduction to the power converters 16 and 32 according to the states of the accelerator 74, the brake 76, and the clutch 78. The circuit supplies a signal and also supplies an open / close control signal to the switch circuit 72, and can be configured by, for example, a microprocessor system. That is, the control circuit 73 determines that the regenerative state or the power running state is in a state where the clutch 78 is engaged. In this state, if the accelerator 74 is on and the brake 76 is off, it is determined that the vehicle is in a power running state. In other cases, that is, regardless of whether the accelerator 74 and the brake 76 are both off. When the brake 76 is on, it is determined that the vehicle is in a regenerative state. In response to this determination, the control circuit 73 generates an appropriate control signal.
[0023]
Next, the operation of the embodiment of FIG. 1 will be further described. When the control circuit 73 determines that the motor 18 is in the power running state, the control circuit 73 closes the switch circuit 72 (makes the switch conductive) and keeps the transistor 62 non-conductive to maintain the second power converter 32. Stop the operation. When the capacitor 24 is charged to a certain voltage by electric energy, the voltage of the capacitor 24 and the voltage of the battery group 26 are added, and the added voltage is stepped down by the first power converter 16 and the DC motor 18. To be supplied. Therefore, the current from the capacitor 24 and the battery group 26 returns to the capacitor 24 via the switch circuit 72, the first power converter 16, and the motor 18, a closed circuit is formed, and the motor 18 rotates.
[0024]
At this time, when a large amount of power is required, the electric energy of the capacitor 24 helps supply the power. The control circuit 73 controls the shock coefficient of the control pulse signal based on the relationship between the state of the accelerator 74 and the voltage supplied to the motor 18 (connection lines for monitoring this voltage are not shown). The transistors of the first power converter 16 are turned on and off. Since the input voltage is allowed to pass through the motor 18 only when conducting, the rate of step-down can be controlled by controlling the impact coefficient of the pulse signal (that is, the average value of the electrical energy passed during conduction to the entire time is supplied to the motor 18. Corresponding to the voltage supplied). With this control, the rotational state of the motor 18 can be controlled as desired by the driver. At this time, since the capacitor 24 and the battery group 26 are connected in series, even if the voltage of the capacitor 24 decreases sequentially, the voltage at the upper end of the battery group 26 is always sufficiently at least the voltage of the battery. The electric energy of the capacitor 24 can be used until the voltage of the capacitor becomes zero. By the way, when the motor 18 is powered, the charging voltage decreases as the discharging of the large-capacitance capacitor 24 proceeds, and the polarity is reversed when the amount of stored electricity becomes zero. The diode 36 conducts when the polarity of the capacitor 24 is to be reversed, and prevents this polarity reversal. During the period when the polarity of the capacitor 24 is not reversed, the diode 36 is non-conductive and does not affect the operation of the device of FIG.
[0025]
When the control circuit 73 determines that the motor 18 is in the regenerative state, the control circuit 73 opens the switch circuit 72 (makes it non-conductive), and makes the transistor 62 repeatedly conductive and non-conductive with an appropriate impact coefficient. Then, the second power converter 32 is operated. Since the switch circuit 72 is non-conductive, the voltage from the capacitor 24 and the battery group 26 does not pass through the first power converter 16 and the drive voltage is not supplied to the motor 18. Therefore, the motor 18 functions as a generator and generates a generated voltage, that is, a regenerative voltage. This regenerative voltage is supplied to the capacitor 24 via the first power converter 16 and the second power converter 32 and charges the capacitor 24. This charging voltage is reused when the motor is powered.
[0026]
By the way, when there is no 2nd power converter 32, the regeneration direction turns into the capacitor | condenser 24 through the 1st power converter 16 from the motor 18, but if the voltage of the capacitor | condenser 24 falls, the motor 18 at the time of regeneration will be shown. The electromotive force becomes higher, and regenerative control cannot be performed as described above. The second power converter 32 is a step-down converter installed to prevent regenerative control from being disabled, and is not in an uncontrollable state regardless of the electromotive force of the motor. After rectification (in an uncontrollable state) by the first power converter 16, it may be stepped down (in a controllable state) by the second power converter 32, or may be stepped up (controllable by the first power converter 16). The second power converter 32 may step down the voltage (in a controllable state). In this case, the control circuit 73 needs to monitor the respective outputs (voltage, current) of the first power converter 16 and the second power converter 32 to control these power converters. This is due to the following reason. That is, whether the first power converter 16 becomes uncontrollable or controllable depends on the voltage of the electrolytic capacitor provided in the power converter 16. On the other hand, the control circuit 73 manages the terminal voltage of the electrolytic capacitor by adjusting the power taken in by the first power converter 16 and the power taken out by the second power converter 32.
[0027]
When the control circuit 73 determines that neither power running nor regeneration is performed according to the state of the accelerator 74, the brake 76, and the clutch 78, the operation of the first power converter 16 and the second power converter 32 is stopped. Further, when the motor 18 is stopped, for example, before the start of the electric vehicle, in order to charge the capacitor 24 by the battery 26, the switch circuit 72 is closed (conducted), the operation of the first power converter 16 is stopped, The second power converter 32 is operated with an appropriate impact coefficient. In this case, the second power converter 32 must have a configuration in which the input end and the output end are insulated in order to prevent the battery group 26 from being short-circuited.
[0028]
Although the preferred embodiment of the present invention has been described above, various modifications and changes can be made by those skilled in the art without departing from the spirit of the present invention. For example, the motor may be a DC brushless motor, an AC induction motor, an AC synchronous motor, or a single-phase motor or a three-phase motor other than those described in the embodiments (DC motor). A chopper or an inverter corresponding to these motors can be used for the first power converter, and a chopper or a DC / DC converter can be used for the second converter. As the capacitor, a capacitor in which a plurality of capacitors are connected in parallel may be used. Further, a small number of capacitors may be connected in series instead of one capacitor. Note that when a small number of capacitors are connected in series, the variation in the voltage of each capacitor is less than in the case of a large number of capacitors connected in series.
[0029]
[Effects of the present invention]
As described above, according to the motor driving power supply device of the present invention, since the capacitor and the battery are connected in series, the power storage energy of the capacitor can be used until it becomes completely zero when the motor is powered. When a battery is connected in series with a capacitor and discharged, the voltage can be increased by the amount of the capacitor compared to the case of the battery alone. Here, if the power supplied to the first power converter is the same, the discharge current of the battery, that is, the load can be reduced as much as the voltage increases. For this reason, since a large-capacity capacitor can be used with a low voltage specification, an inexpensive electric double layer capacitor can be used. Furthermore, since another circuit is not connected between the first power converter and the motor, a combination of a commercially available motor and power converter that are optimally matched in advance can be used as they are. In addition, when the second power converter has a configuration in which the input end and the output end are insulated, the capacitor can be charged by the battery via the switch circuit and the second power converter, so the capacitor is charged even when the motor is stopped. it can. When the electric vehicle travels in an urban area, acceleration (power running) and deceleration (regeneration) are repeated as appropriate, and the capacitor is repeatedly discharged (power running) and charged (regeneration) according to acceleration and deceleration. Therefore, the capacitor maintains a voltage range reflecting the running state, and the effect of reducing the load on the battery during power running is also maintained.
[Brief description of the drawings]
FIG. 1 is a block diagram of a preferred embodiment of a power supply apparatus for driving a motor according to the present invention.
FIG. 2 is a block diagram of an example of a conventional motor driving power supply device.
FIG. 3 is a circuit diagram of an example of a power converter.
FIG. 4 is a block diagram of another example of a conventional motor driving power supply device.
FIG. 5 is a block diagram of still another example of a conventional motor driving power supply device.
FIG. 6 is a circuit diagram of another example of the power converter.
[Explanation of symbols]
16 First power converter
18 Motor
24 capacitors
26 batteries
32 Second power converter
36 diodes
72 Switch circuit
73 Control circuit
74 Accelerator
76 Brake
78 Clutch

Claims (5)

A series circuit of a battery and a capacitor;
A first power converter having a first input / output terminal coupled to both ends of the series circuit via a switch circuit, and a second input / output terminal coupled to the motor;
A second power converter having an input terminal coupled to a common connection point of the switch circuit and the first power converter, and an output terminal coupled to a common connection point of the battery and the capacitor of the series circuit;
A control circuit for controlling the opening and closing of the switch circuit,
The first input / output terminal is electrically connected directly to the switch circuit;
During power running of the motor, the control circuit maintains the conductive state by closing the switch circuits, the power from the series circuit via the switch circuit and the first power converter is supplied to the motor,
During regeneration of the motor, the control circuit opens the switch circuit, and characterized in that the generated power of the motor is charged to the capacitor through a first power converter and said second power converter described above Motor drive power supply. 2. The motor drive power supply device according to claim 1, wherein the control circuit controls the second power converter to stop operating during the power running. 3. 2. The motor drive according to claim 1, wherein the control circuit controls the switch circuit and the second power converter to charge the capacitor with the battery during a stop period of the motor. Power supply. The first power converter is a chopper circuit or an inverter circuit that performs a step-down operation from the series circuit in the direction of the motor and performs a step-up operation or a rectification operation from the motor in the direction of the series circuit. The motor drive power supply device according to claim 1 . 2. The motor driving power source according to claim 1, wherein the second power converter is a chopper circuit or a DC / DC converter circuit that performs a step-down operation from the first power converter toward the capacitor. apparatus.

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