JP5288178B2 - Motor drive system - Google Patents

Description

  The present invention relates to a motor drive system including a plurality of motor drive devices that drive a motor by a power converter, and particularly to a motor drive system that can charge a battery without using a dedicated charging device.

  In order to efficiently operate the motor, a method of boosting the power supply voltage and driving the motor with a power converter is known for the purpose of reducing the input current of the motor. This type of motor drive system is described in Patent Document 1, for example, and the outline thereof is as shown in FIG.

7, 101 and 102 are inverters, 103 is a capacitor, 201 and 202 are motors such as synchronous motors connected to the AC side of each inverter, and 104 is a neutral point of the stator winding of one motor 202. Reference numeral 105 denotes a control unit which is a battery serving as a DC power source connected between the DC bus and the negative DC bus.
In the above configuration, one inverter 102 drives the motor 202 by outputting an AC voltage while boosting so that the voltage of the capacitor 103 is higher than the voltage of the battery 104, and the other inverter 101 performs boosting operation. The AC voltage is output without driving the motor 201 independently of the motor 202.

In the above prior art, since the motors 201 and 202 are driven using the DC power stored in the battery 104, the battery 104 is repeatedly discharged and charged along with the power running and regenerative operation of these motors. However, the kinetic energy of the motors 201 and 202 cannot be regenerated, and the amount of power stored in the battery 104 gradually decreases due to various losses and power consumption of the electrical components.
For this reason, a charging device for charging the battery 104 is required. However, if a dedicated charging device is provided, there is a problem that the entire device becomes large or the cost increases due to an increase in the number of parts.

  In order to solve this problem, Patent Document 2 discloses that the stator winding of the motor is used as a boosting reactor, and the switching element of the inverter that drives the motor is turned on / off so that torque for rotating the motor is not generated. Discloses an in-vehicle charging apparatus in which a battery is charged from a commercial power source.

FIG. 8 shows an outline of the above-described on-vehicle charging apparatus, where 106 and 107 are inverters, 108 is a capacitor, 109 is a battery, 110 is a breaker, 111 is a polarity determination unit, 112 is a control unit, 113 is a switch, 203, Reference numeral 204 denotes a motor, and 300 denotes a single-phase commercial power source.
In the above configuration, both ends of the commercial power supply 300 are connected to the neutral points of the stator windings of the two motors 203 and 204 via the breaker 110, and an equal current is supplied to each phase winding of these motors 203 and 204. The switching elements of the inverters 106 and 107 are on / off controlled so as to flow.
As a result, the battery 109 is charged from the commercial power supply 300 via the motors 203 and 204, the inverters 106 and 107, and the switch 113 without offsetting the magnetic field generated in the windings and rotating the motors 203 and 204. .

JP 2002-10670 A (paragraphs [0022] to [0029], FIGS. 1 to 3 etc.) Japanese Patent No. 3275578 (paragraphs [0008] to [0015], FIG. 1, FIG. 2, etc.)

  However, the prior art described in FIG. 8 (Patent Document 2) is a charging device intended for a circuit configuration in which a commercial power supply 300 that supplies power to the battery 109 is connected to the neutral point of the motors 203 and 204. Therefore, as shown in FIG. 7 (Patent Document 1), it cannot be applied to a drive system having a circuit configuration in which a battery is connected between the neutral point of the motor and the DC bus.

  Therefore, the problem to be solved by the present invention is that in a circuit configuration in which a battery is connected between the neutral point of a motor and a DC bus as in Patent Document 1, power is transferred between the battery and the capacitor by a power converter. The battery is charged and the motor is driven at the same time, and the stator winding of the motor is used as a reactor in the same manner as in Patent Document 2, and the rotational torque of the motor is not generated when the battery is charged. It is to provide a simple motor drive system.

In order to solve the above-mentioned problem, the invention according to claim 1 includes one power converter having an energy storage element connected to the DC side;
A motor driven by AC power output from the power converter, and having a battery connected between a neutral point of the stator winding and one DC bus of the power converter;
The energy storage element is connected to the DC side, and another power converter in which an AC power source is connected to the AC side; and
Other motors connected to the AC side of this power converter via disconnect means,
In a motor drive system with
Connecting the neutral point of the stator winding of the other motor and the neutral point of the stator winding of the one motor;
The other power converter is operated as a rectifier in a state where the other power converter and the other motor are separated by the separating means, and DC power is stored in the energy storage element, and the one power converter When a zero voltage vector is output, a direct current is passed from the one power converter to the stator windings of the one motor that acts as a step-down reactor without generating torque for rotating the one motor. The battery is charged through a stator winding of the one motor .
The invention according to claim 2 is configured such that the neutral point of the other motor in claim 1 is not connected to one end of the battery (the neutral point of the one motor).
According to a fourth aspect of the present invention, the disconnecting unit is configured by a switch unit that turns on and off the connection between the other power converter and the other motor.

According to a third aspect of the present invention, in the motor drive system according to the first or second aspect , the other power converter is controlled to flow a sine wave current having a power factor of 1 with respect to the voltage of the AC power supply. .

The invention according to claim 5 is the motor drive system according to any one of claims 1 to 4 , wherein a power switch is connected between the other power converter and the AC power supply. In the system, before applying the AC power supply voltage to the other power converter by turning on the power switch, the voltage of the battery is boosted by the one power converter to set the energy storage element to a predetermined voltage value. To charge up to.
In this case, the charging voltage value of the energy storage element is preferably near the peak value of the AC power supply voltage as described in claim 6 .

According to the present invention, in a motor drive system in which a motor drive device that simultaneously performs a boost operation and a motor drive between a battery and a capacitor by a power converter and another motor drive device are connected in parallel, The battery can be efficiently charged by using existing components such as a stator winding. For this reason, it is not necessary to provide a dedicated charging device, which can contribute to simplification of the configuration and cost reduction.
In addition, by controlling the power converter and allowing a direct current to flow through the motor, the battery can be charged without generating torque for rotating the motor, and a vehicle or the like equipped with this drive system moves unexpectedly. Can be prevented. Furthermore, a sine wave current having a power factor of 1 can be supplied to the AC power supply voltage by controlling another power converter connected to the AC power supply.
Further, when a power switch is connected to the AC power supply side of another power converter, before the AC power is turned on by this power switch, the energy storage element is connected to a predetermined power source from the battery via one power converter. By charging to a voltage value, an inrush current to the energy storage element when the AC power is turned on can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit configuration diagram showing a first embodiment of the present invention according to claims 1 and 4 . The motor drive system according to this embodiment includes a three-phase AC power supply 10 that is a commercial power supply, a relay circuit 11 connected between the AC power supply 10 and a power converter 20 described later, and a star-connected fixed circuit. Two AC motors (hereinafter simply referred to as “motors”) 40 and 50 having child windings, and a separation disposed between the connection point of the relay circuit 11 and the power converter 20 and the stator windings of the motor 40. a switch 12 as a means, a semiconductor switch _Tr 1 to Tr ₆ and _Tr 7 2 sets of power converters 20 and 30 made of _{to Tr 12} and inverse parallel connected transistors and diodes, stator windings of the motor 40, 50 The battery 60 connected between the neutral points 41 and 51 and one end of the DC input terminal (negative input terminal) of the power converters 20 and 30 is connected between the DC input terminals of the power converters 20 and 30. Electrolytic capacitor 14 as a stored energy storage element, voltage detector 15 for detecting the voltage, voltage detector 16 for detecting the voltage of battery 60, and current detector 17 for detecting the current flowing into battery 60 , Generates and outputs drive signals (PWM pulses) PWM ₁ and PWM ₂ for controlling the power converters 20 and 30 based on the detection values V _dc , V _b and I _b detected by the detectors 15, 16 and 17. It is comprised from the control apparatus 70 which performs.

As is apparent, the power converters 20 and 30 constituting the two sets of motor drive devices are connected in parallel with the capacitor 14 between the DC input terminals in common, and are connected to the AC output terminal of the power converter 20. A neutral point 41 of the motor 40 connected via the switch 12 and a neutral point 51 of the motor 50 directly connected to the AC output terminal of the power converter 30 are connected to the negative DC bus via the battery 60. It is connected.
Here, the power converter 30 is “one power converter”, the motor 50 is “one motor”, the power converter 20 is “other power converter”, and the motor 40 is “ It corresponds to “other motor” respectively.

Next, the charging operation of the battery 60 in this embodiment will be described.
First, in a state where the switch 12 is turned off and the one power converter 20 and the motor 40 are disconnected, the three-phase AC power of the AC power supply 10 is transferred to the relay circuit 11 including an initial charging circuit, a switch, and the like (not shown). To the AC side of the power converter 20.
AC power supplied via the relay circuit 11 is AC / DC converted by the power converter 20, and DC power is stored in the capacitor 14. At this time, since the off signal is input as the drive signal PWM ₁ from the control device 70 to the semiconductor switches Tr _{1 to} Tr ₆ of the power converter 20, the power converter 20 substantially becomes a diode bridge and is a normal diode. The operation is the same as that of the rectifier.

The DC power stored in the capacitor 14 is DC / DC converted by the other power converter 30 and supplied from the AC output terminal to the battery 60 via the stator winding of the motor 50 to charge the battery 60. .
At this time, the power converter 30 performs DC / DC conversion by performing PWM control using two types of zero voltage vectors that turn on all upper arms or lower arms (turn off the other arm). The operation will be described in detail below.

FIG. 2 is an operation explanatory diagram of the power converter 30.
At the time of the zero voltage vector output, the upper arm semiconductor switches and the lower arm semiconductor switches are simultaneously turned on or off. Therefore, here, the upper arm semiconductor switches Tr ₇ ,. In the following description, it is assumed that Tr ₉ and Tr ₁₁ are single semiconductor switches Tr _p and the lower arm semiconductor switches Tr ₈ , Tr ₁₀ , and Tr ₁₂ are single semiconductor switches Tr _n .
FIG. 2 (a) circuit operation when the semiconductor switch Tr _p is on, FIG. 2 (b) the circuit operation when the semiconductor switch Tr _n is on, FIG. 2 (c) the voltage waveform in the circuit, Each current waveform is shown. In FIGS. 2A and 2B, the semiconductor switch in the on state is circled.

In the on period _{T pon} semiconductor switch Tr _p in FIG. 2 (c), the current _{I b} flowing through the battery 60 is increased exponentially through the inductor in the stator windings of the motor 50. On the other hand, in the on-period T _non of the semiconductor switch Tr _n , the current I _b flowing through the battery 60 circulates through the diode of the semiconductor switch Tr _n by the energy stored in the reactor and attenuates exponentially. The broken line in FIG. 2 (a), (b) is a path of the current _{I b.}
By these operations, the semiconductor switch Tr _p , Tr _n is turned on / off according to the duty ratios of the periods T _pon , T _non , so that the battery 60 can be charged while operating the power converter 30 as a general buck-boost chopper. it can.

The control device 70 shown in FIG. 1 includes the voltage detection value V _dc of the capacitor 14 detected by the voltage detector 15, the voltage detection value V _b of the battery 60 by the voltage detector 16, and the battery 60 by the current detector 17. The drive signal PWM ₂ is generated using the current detection value _Ib, and the semiconductor switches Tr _{7 to} Tr ₁₂ of the power converter 30 are turned on and off to output a zero voltage vector, whereby a constant charging current is generated in the battery 60. Control to flow. And the control apparatus 70 will complete | finish the charging operation by the power converter 30, if the full charge state of the battery 60 is detected based on the voltage detection value _Vb .
Except when the power converter 30 outputs a zero voltage vector, the motor 50 is driven by supplying three-phase AC power from the power converter 30 to the motor 50 by operating as a normal three-phase voltage source inverter. To do.

Here, as described in claim 2, the neutral point 41 of the motor 40 and the positive electrode of the battery 60 may not be connected. Also in this case, the battery 60 can be charged by the operation of the power converter 30 described above.
In addition, as described in claims 1 and 2 , while the battery 60 is being charged by the power converter 30, a direct current flows in each phase coil of the motor 50, so that no rotating magnetic field is generated and no torque is generated. . Therefore, the battery 60 can be charged without rotating the motor 50, and it is possible to prevent a vehicle or the like equipped with this drive system from moving unexpectedly.

Next, a second embodiment of the present invention according to claim 3 will be described.
FIG. 3 is a circuit configuration diagram showing the second embodiment. The same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted. Hereinafter, different portions will be mainly described.

In the present embodiment, a power supply voltage detector 13 is provided in the three-phase AC power supply 10, and current detectors 21, 22, and 23 are provided between the power converter 20 and the relay circuit 11. Phase voltage detection value _V r by the power supply voltage detector _13, V s, _{V t} and each phase current detection value _I r by the current detector 21, 22, _23, I s, and _{I t,} by the voltage detector 15 The voltage detection value V _dc is input to the control device 70, and the control device 70 generates and outputs a drive signal PWM ₁ so that the power converter 20 operates as a PWM rectifier.
Since there are various control methods for the PWM rectifier, an example thereof will be described with reference to FIG.

In FIG. 4 showing the function of the control device 70, the deviation between the DC link voltage command V _dc ^* and the voltage detection value V _dc is input to the voltage regulator 71, and an AC current amplitude command is generated. On the other hand, the phase voltage detection values V _r , V _s , and V _t are input to the PLL circuit 72 to obtain a reference sine wave having the same phase as that of the three-phase AC power supply 10. Phase current command _I ^r * by multiplying the reference sine wave and said alternating current amplitude _command, ^I s _*, generates the _I ^{t *.} Then, the phase current command ^{_{I r *, I s *,}} I t * and the phase current detection value _{I r,} I s, enter the deviation between _{I t} to the current regulator 73, the phase voltage command _{V r} ^* , V _s ^* , V _t ^* are obtained. Each phase voltage command V _r ^* , V _s ^* , V _t ^* and the triangular wave carrier output from the triangular wave carrier generator 74 are input to the PWM pulse generator 75 to generate a drive signal (PWM pulse) PWM _1. The drive signal PWM ₁ is output to the power converter 20.
By operating the power converter 20 as a PWM rectifier as described above, a sine wave current having a power factor of 1 can be supplied to the power supply voltage.

Next, a third embodiment of the present invention according to claims 5 and 6 will be described.
In the first embodiment described above, the AC power of the three-phase AC power supply 10 is rectified by the diodes of the semiconductor switches Tr _{1 to} Tr ₆ constituting the power converter 20 via the relay circuit 11 to charge the capacitor 14. ing. However, as shown in FIG. 5A, when the relay circuit 11 is constituted by, for example, the power switch 11a, the charging current _Ich of the capacitor 14 becomes a large value depending on the turn-on timing of the power switch 11a.

In general, the diode (freewheeling diode) antiparallel to the semiconductor switches Tr _{1 to} Tr ₆ constituting the power converter 20 places importance on switching characteristics when operating as an inverter, and charges the capacitor 14 when the power is turned on. The ability to withstand the inrush current is inferior to that of a general rectifier diode.
Therefore, as shown in FIG. 5 (b), there is a risk of destroying the semiconductor switch _Tr 1 to Tr ₆ by a charging current (rush _{current) I ch} capacitor 14 flowing at the time of turn-on of the power switch 11a. Further, by the rush current I _ch, there or the power supply voltage is momentarily reduced as indicated by the broken line in FIG. 5 (b), a possibility that breaker malfunctions.
In order to prevent these inconveniences, it is conceivable to attach an initial charging circuit having a resistor or the like to the relay circuit 11, but this causes an increase in cost due to an increase in the number of components and an increase in the size of the apparatus.

Therefore, in the third embodiment of the present invention, the inrush current _Ich when the three-phase AC power supply 10 is turned on is suppressed without increasing the number of components.
The circuit configuration of the third embodiment is the same as that of the first embodiment of FIG. 1, but a relay circuit connected between the three-phase AC power supply 10 and the power converter 20 as shown in FIG. 11 is a power switch 11a.

The operation of the third embodiment will be described. When the battery 60 is charged, the switch 12 in FIG. 5 is turned off in advance to disconnect the power converter 20 and the motor 40, and then the power switch 11a is turned on. Although it is the same as that of embodiment, in this embodiment, the power converter 30 is PWM-operated before turning on the power switch 11a.
FIG. 6 is an operation explanatory diagram of the third embodiment. When the power converters 20 and 30 are not operating, the voltage V _{dc of the} capacitor 14 is substantially equal to the voltage V _{b of the} battery 60. When a charge start command is issued from the control device 70 at time t ₀ in FIG. 6, the drive signal PWM ₂ is given to the semiconductor switches Tr _{7 to} Tr ₁₂ of the power converter 30, and the power converter 30 Two types of zero voltage vectors that turn on the lower arm are output to perform DC / DC conversion. As a result, the capacitor 14 is charged and boosted until its voltage V _dc is near the peak value of the power supply voltage V _s . Here, the drive signal PWM ₂ may be appropriately generated according to the capacity of the power converter 30 (allowable current, thermal duty, etc.).
The circuit operation when the semiconductor switches Tr ₇ , Tr ₉ , Tr ₁₁ (Tr _p ) on the upper arm of the power converter 30 are turned on, and the semiconductor switches Tr ₈ , Tr ₁₀ , Tr ₁₂ (Tr _n ) on the lower arm are turned on. The circuit operation when turned on is the same as that in FIGS. 2A and 2B described above, and the power converter 30 operates as a general step-up / step-down chopper.

When the voltage detector 15 detects that the voltage V _dc of the capacitor 14 has reached the vicinity of the peak value of the power supply voltage V _s at time t ₁ in FIG. 6, the drive signal PWM ₂ is turned off, and then at time t ₂ . Turn on the power switch 11a. At this time, since there is almost no potential difference between the three-phase AC power supply 10 and the capacitor 14, the current flowing into the capacitor 14 via the diode of the power converter 20 can be minimized.
Thereafter, the battery 60 may be charged by the method described in the first embodiment.

Incidentally, the boosted voltage of the capacitor 14, the voltage drop characteristics of the input time delay and the capacitor 14 of the power switch 11a, no problem set higher than the peak value of the power supply voltage V _s. When a step-up or step-down transformer is inserted between the three-phase AC power source 10 and the power switch 11a, the voltage of the capacitor 14 is stepped up to near the peak value of the secondary side voltage of these transformers. It ’s fine.
As described above, according to the third embodiment, since an inrush current to the capacitor 14 can be suppressed without separately providing an initial charging circuit, an increase in the cost associated with an increase in the number of parts and a large size of the entire apparatus. Can be prevented.
The third embodiment is also applicable to the circuit configuration of the second embodiment.

In each of the above-described embodiments, the motor driving system (system including two motor driving devices) that drives the two motors 40 and 50 by the individual power converters 20 and 30 has been described.
However, in the present invention, like the motor 50 driven by the power converter 30, the battery 60 is connected between the neutral point 51 and one DC bus of the power converter 30. It suffices to have another power converter (for example, power converter 20) that charges the capacitor 14 as an energy storage element from the AC power supply 10, and the number of these other power converters 20 and motors 40 as loads thereof. (In other words, the number of other motor driving devices) is not limited at all. That is, the present invention can be applied to a system including a plurality of motor drive devices.

It is a circuit block diagram which shows 1st Embodiment of this invention. It is operation | movement explanatory drawing of the power converter in FIG. It is a block diagram which shows 2nd Embodiment of this invention. It is a block diagram which shows the function of the control apparatus in FIG. It is a figure for demonstrating the problem of 1st Embodiment. It is operation | movement explanatory drawing of 3rd Embodiment of this invention. It is a circuit block diagram which shows a prior art. It is a circuit block diagram which shows a prior art.

Explanation of symbols

10: Three-phase AC power supply 11: Relay circuit 11a: Power switch 12: Switch 13: Power supply voltage detector 14: Capacitor (energy storage element)
15, 16: Voltage detector 17: Current detector 20, 30: Power converter 21, 22, 23: Current detector 40, 50: Motor 41, 51: Neutral point 60: Battery 70: Controller 71: Voltage Regulator 72: PLL circuit 73: Current regulator 74: Triangular wave carrier generator
75: PWM pulse generator _Tr 1 _{to Tr 12:} semiconductor switch

Claims (6)

One power converter with an energy storage element connected to the DC side;
A motor driven by AC power output from the power converter, and having a battery connected between a neutral point of the stator winding and one DC bus of the power converter;
The energy storage element is connected to the DC side, and another power converter in which an AC power source is connected to the AC side; and
Other motors connected to the AC side of this power converter via disconnect means,
In a motor drive system with
Connecting the neutral point of the stator winding of the other motor and the neutral point of the stator winding of the one motor;
The other power converter is operated as a rectifier in a state where the other power converter and the other motor are separated by the separating means, and DC power is stored in the energy storage element, and the one power converter When a zero voltage vector is output, a direct current is passed from the one power converter to the stator windings of the one motor that acts as a step-down reactor without generating torque for rotating the one motor. The battery is charged through a stator winding of the one motor. One power converter with an energy storage element connected to the DC side;
A motor driven by AC power output from the power converter, and having a battery connected between a neutral point of the stator winding and one DC bus of the power converter;
The energy storage element is connected to the DC side, and another power converter in which an AC power source is connected to the AC side; and
Other motors connected to the AC side of this power converter via disconnect means,
In a motor drive system with
The other power converter is operated as a rectifier in a state where the other power converter and the other motor are separated by the separating means, and DC power is stored in the energy storage element, and the one power converter When a zero voltage vector is output, a direct current is passed from the one power converter to the stator windings of the one motor that acts as a step-down reactor without generating torque for rotating the one motor. The battery is charged through a stator winding of the one motor. In the motor drive system according to claim 1 or 2,
A motor drive system characterized in that a sine wave current having a power factor of 1 is supplied to the voltage of the AC power supply by controlling the other power converter . In the motor drive system given in any 1 paragraph of Claims 1-3,
The motor drive system according to claim 1, wherein the disconnecting means is a switch means for switching on and off the connection between the other power converter and another motor . The motor drive system according to any one of claims 1 to 4 , wherein a power switch is connected between the other power converter and the AC power supply .
Before applying the AC power supply voltage to the other power converter by turning on the power switch, the voltage of the battery is boosted by the one power converter to charge the energy storage element to a predetermined voltage value. A motor drive system characterized by that. In the motor drive system according to claim 5 ,
Wherein the predetermined voltage value, a motor drive system characterized a peak value near der Rukoto voltage of the AC power source.

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