JP2009131021A - Motor driving system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor driving system which arbitrarily and dynamically distributes duty of a voltage boosting operation and minimizes circuit loss in accordance with an electric constant and an operation state of a motor driving device having a voltage boosting function. <P>SOLUTION: The motor driving system is provided with a multi-phase voltage-type inverter INV<SB>1</SB>, a smoothing capacitor C<SB>1</SB>connected to the DC input terminal of the inverter, a motor M<SB>1</SB>, where a stator winding is star-connected to an AC output terminal of the inverter INV<SB>1</SB>, and a battery BATT connected between a neutral point of the stator winding and one DC bus bar of the inverter INV<SB>1</SB>. The system is also provided with a plurality of motor drive devices 101 and 102, having voltage boosting functions for boosting the voltage of the battery BATT and supplying it to the smoothing capacitor C<SB>1</SB>; the neutral points of the motors M<SB>1</SB>and M<SB>2</SB>are connected in common and positive sides and negative sides of the DC bus bars are connected in common; and the distribution factor of the zero-phase current flowing in the neutral points of the motors M<SB>1</SB>and M<SB>2</SB>can be controlled by the voltage boosting operation. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technique for mainly reducing circuit loss in a motor drive system including a plurality of motor drive devices that drive a motor by a multiphase voltage source inverter.

  Various systems for driving motors by voltage source inverters have been provided. For the purpose of improving efficiency and the like, systems for driving motors by boosting the DC voltage of a power source using an inverter are known in order to reduce circuit current. ing.

For example, Patent Document 1 discloses a technique of connecting a motor drive device having a boost function by an inverter and a motor drive device not having a boost function via a DC bus.
Patent Document 2 discloses a technique of connecting two motor drive devices having individual power supply means such as a DC power source and having a boosting function by an inverter via a DC bus.
Further, Patent Document 3 discloses a technique for reducing a circuit current ripple by increasing a PWM carrier frequency (switching frequency) in order to reduce a loss of a component in a motor driving device having a boost function by an inverter. Has been.

JP 2002-291256 A (paragraphs [0040] to [0045], FIG. 5 etc.) JP 2002-10670 A (paragraph [0041], FIG. 11, FIG. 12, etc.) International Publication No. WO2002-065628 (20th page, 12th line to 28th line, 22nd page, 10th line to 23rd page, 5th line, FIG. 1, FIG. 9 etc.)

However, in the prior art according to Patent Document 1, there is one inverter that performs a boosting function, and this inverter must bear the boosting energy of a plurality of inverters, so that loss is concentrated.
Moreover, in the prior art which concerns on patent document 2, although the loss which generate | occur | produces at the time of pressure | voltage rise is disperse | distributed to two motor drive devices, when a power supply means is used as a storage battery, since these storage batteries exist separately, power Under the influence of the remaining amount, there is little freedom to individually set the boost operation. As a result, it is not possible to freely control the duty ratio of the boosting function among the plurality of motor driving devices.
Further, as described in Patent Document 3, the method of increasing the PWM carrier frequency to reduce the current ripple and reducing the circuit loss has a problem of increasing the loss of the switching element.

  Therefore, the problem to be solved by the present invention is that a motor capable of minimizing circuit loss by arbitrarily and dynamically assigning the responsibility of the boosting operation according to the electric constant and the operating state of the motor driving device having the boosting function individually. It is to provide a drive system.

  In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a multi-phase voltage source inverter, power storage means connected to the DC input terminal of the inverter, and a stator winding connected to the AC output terminal of the inverter. A connected motor, and a power source connected between a neutral point of the stator winding and one of the DC buses of the inverter, and boosting the voltage of the power source to store the power In a motor drive system comprising a plurality of motor drive devices having a boosting function to be supplied to the means, the neutral point of each motor is connected in common and the positive side and the negative side of the DC bus are connected in common. Is.

  According to a second aspect of the present invention, in the motor drive system according to the first aspect, the motor drive system further comprises a control means for determining a distribution ratio of the zero-phase current flowing to the neutral point of each motor by the boosting operation of each motor drive device. It is.

  As a method of controlling the distribution ratio, the winding resistance value of each motor as described in claim 3, the temperature of each motor as described in claim 4, and each inverter as described in claim 5 are configured. The temperature can be determined using the temperature of the semiconductor switching element to be used, or the positive phase current flowing through each motor as described in claim 6.

  The step-up function of each motor drive device is, as described in claim 7, turning on all semiconductor switching elements of the upper arm or lower arm of the inverter to output a zero-phase voltage and operating the inverter as a step-up chopper. It can be realized by the function.

According to the present invention, in a motor drive system composed of a plurality of motor drive devices each having a boosting function, an electrical constant such as a motor winding resistance of each motor drive device, a motor temperature corresponding to an operating state, a switching element Motor drive that minimizes circuit losses such as conduction loss of motor windings by arbitrarily and dynamically determining the distribution ratio of the zero-phase current that flows with the boost operation according to temperature, positive phase current, etc. A system can be provided.
At the same time, it is also possible to avoid the temperature rise caused by the conduction loss from being concentrated on a specific motor drive device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 is a block diagram showing a first embodiment of the present invention.
In Figure 1, 101 and 102 are parallel-connected motor driving device to each other, a first motor drive device 101 includes a smoothing capacitor C ₁ as the power storage unit, the DC input terminal connected to both ends, and A three-phase voltage source inverter INV ₁ having a self-extinguishing type switching element such as an IGBT and semiconductor switching elements T _{11 to} T ₁₆ composed of a free-wheeling diode, and a three-phase induction motor (hereinafter referred to as an AC output terminal) simply called a motor) and M _1, and a. Similarly, the second motor driving apparatus 102 includes a three-phase voltage source inverter INV ₂ having a smoothing capacitor C ₂ and semiconductor switching elements T _{21 to} T _26, and a motor M ₂ connected to the AC output terminal. , Is composed of.

The neutral point of the stator winding of the motors M ₁ and M ₂ connected in star is commonly connected to the positive electrode of the battery BATT as a power source. Further, the DC buses of the driving devices 101 and 102 are connected in common on the positive side and on the negative side, and the DC side bus on the negative side is connected to the negative electrode of the battery BATT.
Instead of the battery BATT, a rectified power source including an AC power source and a diode bridge may be used.

Here, the motor drive devices 101 and 102 including the inverters INV ₁ and INV ₂ are configured to boost the DC voltage of the battery BATT and smooth the capacitor as described in Reference Document 1 (Japanese Patent No. 3223842), for example. A step-up operation is performed to supply C ₁ and C ₂ (between the DC buses).
Hereinafter, the step-up operation of the motor drive device will be described in detail.

Here, the first motor driving apparatus 101 will be described as an example.
As described in Reference 1, all the switching elements T _{11 to} T ₁₃ of the upper arm of the three-phase voltage source inverter INV ₁ of the motor driving device 101 or all the switching elements T _{14 to} T ₁₆ of the lower arm are connected. When turned on, a zero voltage vector can be output. The equivalent circuit at this time is as shown in FIG.

That is, the three arms constituting the inverter INV ₁ of the motor drive device 101 are switched by switching on all the switching elements T _{11 to} T _{13 of the} upper arm or all the switching elements T _{14 to} T ₁₆ of the lower arm. It can be regarded as one arm composed of the elements T _z1 and T _z2 , and as described in paragraph [0007] of Reference 1, the DC voltage of the battery BATT is boosted by the on / off operation of the switching elements T _z1 and T _z2. it can be operated as a two-quadrant chopper supplied to the smoothing capacitor C ₁ and.
Here, the motor M ₁ can be considered to reactor L ₁ having a value of leakage inductance.

As described above, the step-up ratio of the step-up chopper realized by controlling the zero voltage vector of the inverter INV ₁ can be controlled by changing the duty for turning on and off the switching elements T _z1 and T _z2 .
Therefore, the motor drive devices 101 and 102 in FIG. 1 control the zero-phase voltage of the inverters INV ₁ and INV _{2 by} the method described in Reference Document 1, so that the battery BATT and the smoothing capacitors C ₁ and C ₂ The zero-phase power exchanged between them, in other words, the zero-phase current can be controlled, whereby the voltages of the smoothing capacitors C ₁ and C ₂ can be adjusted to arbitrary values.

Here, as described in Reference Document 1, since the zero-phase voltage output from the inverters INV ₁ and INV ₂ does not appear in the line voltage, it does not affect the driving operation of the motors M ₁ and M _2. . Accordingly, the positive-phase equivalent circuit of each inverter is as shown in FIG. 3, operates as a normal inverter with respect the drive of the motor M _1, M _2, between the line voltage of the inverter INV _1, INV ₂ and the line By controlling the flowing current, AC power is exchanged between the motors M ₁ and M ₂ .

In FIG. 1, switching elements T _{11 to} T ₁₆ and T _{21 to} T ₂₆ constituting the inverters INV ₁ and INV ₂ are PWM signals (gate signals) G _{u1 to} G _z1 , G _u2 to G 2 generated by the control circuit 200. Driven by _Gz2 . The control circuit 200 includes a microcomputer 200a and a storage device 200b. The control circuit 200 receives a frequency command f ₁ ^* , f ₂ ^* from the outside for each of the inverters INV ₁ and INV ₂ and a current detection value and a voltage detection value, which will be described later. And a function of outputting a PWM signal.

The motor driving device 101, the phase current _i U1det of the motor _{M 1, M 2, i w1det} , i u2det, a current detector 111, 112 for detecting the _{i W2det,} the neutral point of the motor _M 1, _{M 2} Current detection means 121 and 122 for detecting currents (zero phase currents) I _b1det and I _b2det are provided, respectively, and the motor drive device 102 is provided with voltage detection means 130 for detecting the DC bus voltage V _dcdet . . These current detection values i _u1det , i _w1det , i _u2det , i _w2det , I _b1det , I _b2det and the voltage detection value V _dcdet are input to the control circuit 200 together with frequency commands f ₁ ^* and f ₂ ^* .

Next, FIG. 4 shows a circuit configuration for generating gate signals G _{u1 to} G _z1 and G _{u2 to} G _z2 for the switching elements T _{11 to} T ₁₆ and T _{21 to} T ₂₆ in the control circuit 200. The circuit is substantially the same as the circuit described in Reference Document 1 (FIG. 6 of the document).
That is, FIG. 4 is based on a generally used PWM signal generation method, and includes three-phase positive phase AC voltage command values V _u ^* , V _v ^* , V _w ^* and zero phase voltage command values. V ₀ ^* is added by adder 210 for each phase. These added values are compared with a triangular wave as a carrier by a comparator in the PWM generation unit 220, and the output is inverted for each switching element of the upper and lower arms of each phase to obtain gate signals G _{u1 to} G _z1 and G _{u2 to} G. _z2 is generated.
When the switching elements T _{11 to} T ₁₆ and T _{21 to} T ₂₆ are driven by these gate signals G _{u1 to} G _z1 and G _{u2 to} G _z2 , the DC bus voltage of the inverters INV ₁ and INV ₂ is supplied to the battery BATT. The motors M ₁ and M ₂ can be driven while boosting the voltage at a desired boost ratio.

FIG. 5 is a block diagram showing an internal configuration of the control circuit 200. The control circuit 200 is configured as follows.
First, the motor control units 231 and 232 are given predetermined motors M ₁ and M ₂ based on external frequency commands f ₁ ^* and f ₂ ^* and current detection values i _u1det , i _w1det , i _u2det and i _w2det . AC voltage command values V _u1 ^* , V _v1 ^* , V _w1 ^* and V _u2 ^* , V _v2 ^* , V _w2 ^* of amplitude and frequency are calculated. In this embodiment, in order to control the two systems of the motor drive devices 101 and 102 independently, two motor control units 231 and 232 are provided. The control method of the inverters INV ₁ and INV ₂ is described in, for example, Reference 2 (Takayoshi Nakano, “Vector Control of AC Motor”, p. 138 to p. 142, published by Nikkan Kogyo Shimbun, 1996). Although the V / f control is used, the specific contents thereof are publicly known, and detailed description thereof is omitted here.

The zero-phase current distribution control unit 240 calculates the distribution ratio k (0 ≦ k ≦ 1) of the zero-phase current that flows from the inverters INV ₁ and INV ₂ to the motors M ₁ and M ₂ , respectively. Then, the distribution ratio k is determined so that the zero-phase current conduction loss due to the motor winding resistance is minimized.
The step-up operation control unit 250 is based on the zero-phase current detection values I _b1det and I _b2det and the DC bus voltage detection value V _dcdet so that the zero-phase current corresponding to the distribution ratio k flows to the motors M ₁ and M ₂ , respectively. The zero-phase voltage command values V ₀₁ ^* and V ₀₂ ^* for the inverters INV ₁ and INV ₂ are calculated and output.

These zero-phase voltage command values V ₀₁ ^* and V ₀₂ ^* are converted into AC voltage command values V _u1 ^* , V _v1 ^* , V _w1 ^* and V _{u2 in} the adders 211 and 212 of FIG. 5 as described with reference to FIG. ^* , V _v2 ^* , and V _w2 ^* are added to the PWM generation units 221 and 222, respectively.
The PWM generators 221 and 222 generate gate signals G _{u1 to} G _z1 and G _{u2 to} G _z2 for the switching elements T _{11 to} T ₁₆ and T _{21 to} T ₂₆ by comparing the added value and the triangular wave, respectively.

The detailed operation of the zero-phase current distribution control unit 240 is as follows.
That is, assuming that the zero-phase current required to cover the drive power of the motors M ₁ and M ₂ is I ₀ , the boosting operation control unit 250 sets the distribution ratio k output from the zero-phase current distribution control unit 240 to zero. Using the phase current command value I ₀ ^* , current control is performed so that zero-phase currents according to the command values I ₀₁ ^* and I ₀₂ ^* shown in Formulas 1 and ₂ flow in the motors M ₁ and M ₂ .
[Formula 1]
I ₀₁ ^* = k · I ₀ ^*
[Formula 2]
I ₀₂ ^* = (1-k) · I ₀ ^*

Here, it is assumed that the winding resistance values r ₁ and r ₂ of the motors M ₁ and M ₂ are stored in advance in the storage device 200b of the control circuit 200, and these winding resistance values r ₁ and r ₂ and Equation 1 are used. from equation 2, if determining the conduction loss total value generated by the windings of the motor M _1, M _2, the formula 3.
[Formula 3]
P = k ² · I ₀ ^{* 2} · r ₁ + (1−k) ² · I ₀ ^{* 2} · r ₂ = (I ₀ ^{* 2} · r ₁ + I ₀ ^{* 2} · r ₂ ) · k ² −2 · I ₀ ^* · r ₂ · k + I ₀ ^* · r ₂
Here, when k is considered as a variable, Equation 3 is a downward convex quadratic function, and k that gives the minimum value is Equation 4.
[Formula 4]
k = {r ₂ / (r ₁ + r ₂ )}
Thus, in the present embodiment, the motor _M 1, based on the winding resistance value _r 1, _{r 2} of _{M 2,} the motor _M 1, conduction loss is minimized caused by winding of the _{M 2} such distribution rate k (0 ≦ k ≦ 1) is calculated.

Next, FIG. 6 shows the configuration of the step-up operation control unit 250.
The operation will be described. The detected value V _dcdet is fed back to the DC bus voltage command value V _dc ^*, and the output of the PI controller 252 that makes the deviation output from the adder 251 zero is set to the zero-phase current command value. Let it be I ₀ ^* . In accordance with this zero-phase current command value I ₀ ^* , a zero-phase current I ₀ necessary to cover the drive power of the motors M ₁ and M ₂ flows.

Next, the zero-phase current command values I ₀₁ ^* and I ₀₂ ^* to be supplied to the motors M ₁ and M ₂ are calculated by the multiplier 253 and the adder 254 according to the distribution ratio k input from the zero-phase current distribution control unit 240. To do. The zero phase current command values I ₀₁ ^* and I ₀₂ ^* are fed _back to the zero phase current detection values I _b1det and I _b2det of the motors M ₁ and M ₂ , and the deviations output from the adders ₂₅₅ and ₂₅₇ are calculated. The outputs of the PI controllers 256 and 258 that are set to 0 are set as zero-phase voltage command values V ₀₁ ^* and V ₀₂ ^* for the inverters INV ₁ and INV ₂ .
The operation of generating the gate signals G _{u1 to} G _z1 and G _{u2 to} G _z2 for the switching elements T _{11 to} T ₁₆ and T _{21 to} T ₂₆ using these zero-phase voltage command values V ₀₁ ^* and V ₀₂ ^* As described with reference to FIG.

As described above, according to the first embodiment, it is possible to arbitrarily boost the DC bus voltage of each inverter constituting a plurality of motor drive devices, and minimize the conduction loss caused by the boost operation. Can be. In addition, although this embodiment is a motor drive system which consists of the two motor drive devices 101 and 102, the number of motor drive devices is not limited at all.
The motors M ₁ and M ₂ may be multi-phase AC motors other than the three-phase induction motor, and the control method is not limited to V / f control. For example, a control method such as vector control with a speed sensor is used. It may be used.
Furthermore, in the present embodiment, the positive electrode of the battery BATT is connected to the neutral point of the motors M ₁ and M ₂ and the negative electrode of the battery BATT is connected to the negative side of the DC bus, but the positive electrode of the battery BATT is connected to the DC bus. Even if it is connected to the positive side and the negative electrode of the battery BATT is connected to the neutral point of the motors M ₁ and M ₂ , the same effects as those of the present embodiment can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIGS.
The second embodiment is different from the first embodiment in that, as shown in FIG. 7, temperature detection means NTC ₁ and NTC ₂ are attached to the motors M ₁ and M ₂ constituting the motor driving devices 101A and 102A, respectively. The zero-phase current distribution control unit 240 determines the distribution ratio k of the zero-phase current using the temperature detection values Temp ₁ and Temp ₂ based on these, and other parts are the same as in the first embodiment. is there.
Below, the determination method of the distribution rate k in this embodiment is demonstrated.

FIG. 8 shows the difference (Temp ₁ -Temp ₂ ) between the temperature detection values Temp ₁ and Temp ₂ of the motors M ₁ and M ₂ input to the zero-phase current distribution control unit 240 as the horizontal axis and the distribution ratio k as the vertical axis. In this embodiment, a characteristic line passing through coordinates (0, 0.5) as shown by a solid line is used.

According to the solid characteristic line in FIG. 8, when the temperatures of the motors M ₁ and M ₂ are equal, k = 0.5, and the distribution ratio of the zero-phase current is 1: 1. Further, when the temperature of the motor M ₁ is higher than the temperature of the motor M ₂ , the distribution ratio k decreases according to the difference, and the zero-phase current flowing to the motor M ₂ is decreased while the zero-phase current flowing to the motor M ₁ is decreased. increase. Further, if the characteristic line is translated in the vertical direction as shown by a broken line in FIG. 8, the distribution ratio k can be biased, and if the inclination of the characteristic line is changed, the difference in temperature detection values (Temp ₁ − It is also possible to change the sensitivity at which the distribution ratio k changes with respect to Temp ₂ ).

According to the second embodiment, the DC bus voltage of each of the inverters INV ₁ and INV ₂ can be arbitrarily boosted as in the first embodiment, and the motors M ₁ and M ₂ due to loss generated by the boosting operation can be obtained. It is possible to minimize the temperature rise.
In the present embodiment, measures the temperature by the motor _M 1, the temperature detecting means _NTC 1 attached to _{M 2,} NTC _2, without detecting the temperature directly, the motor _M 1, _{M 2} of the current detection A thermal calculation value calculated from the value and the thermal time constant may be used.

Next, a third embodiment of the present invention will be described with reference to FIG.
This embodiment is different from the second embodiment in that the temperature detection values Temp ₁ and Temp ₂ for determining the zero-phase current distribution ratio k are represented by the inverters INV _{1 as} shown in the motor drive devices 101B and 102B in FIG. , INV ₂ is provided with temperature detection means NTC ₁ and NTC ₂ so as to be obtained from switching elements such as T ₁₄ and T ₂₄ . Of course, the temperature detection means NTC ₁ and NTC ₂ may be attached to other switching elements.
Although not shown, the temperature detection means NTC ₁ and NTC ₂ may be attached to the cooling fins of the inverters INV ₁ and INV ₂ to detect the temperature.

Since the determination method of the zero-phase current distribution ratio k in this embodiment is the same as that in the second embodiment, the description thereof is omitted.
According to the present embodiment, as in the second embodiment, the DC bus voltage of each inverter INV ₁ , INV ₂ can be arbitrarily boosted, and the temperature rise of the motors M ₁ , M ₂ associated with the boost operation is minimized. There is an effect that can be done. In this embodiment, the thermal calculation value calculated from the current detection values of the motors M ₁ and M ₂ and the thermal time constant can be used without directly detecting the temperatures of the switching elements and the cooling fins.

Next, a fourth embodiment of the present invention will be described with reference to FIGS.
The circuit configuration of this embodiment is the same as that of the first embodiment (FIG. 1). The difference from the first to third embodiments is the method for determining the zero-phase current distribution ratio k in the zero-phase current distribution control unit 240. is there.

In the present embodiment, for example, current amplitudes I ₁ and I _{2 corresponding} to positive phases of currents flowing through the motors M ₁ and M ₂ are obtained by a method described later. As shown in FIG. 10, the horizontal axis represents the difference (I ₁ -I ₂ ) between the positive phase current amplitudes I ₁ and I ₂ of the motors M ₁ and M ₂ , and the zero phase current distribution ratio k represents the vertical axis. A solid line passing through the coordinates (0, 0.5) on the plane is defined as a distribution rate characteristic.

For example, when the current amplitudes of the positive phases of the motors M ₁ and M ₂ are equal, k = 0.5, and the zero-phase current distribution ratio is 1: 1. The motor with the positive phase current amplitude of the motor M ₁ is greater than the positive phase current amplitude of the motor M _2, the distribution ratio k decreases in accordance with the difference, to reduce the zero-phase current flowing through the motor M ₁ increasing the zero-phase current flowing through the M _2. If the characteristic line is translated in the vertical direction as shown by the broken line, the distribution ratio k can be biased. If the inclination of the characteristic line is changed, the difference in current amplitude between the positive phases of the motors M ₁ and M ₂ can be obtained. The sensitivity at which the distribution ratio k changes with respect to (I ₁ -I ₂ ) can also be changed.

The positive phase current amplitudes I ₁ and I ₂ of the motors M ₁ and M ₂ can be calculated by the calculation means shown in FIG.
That is, a value _obtained by multiplying the zero-phase current detection values I _b1det and I _b2det of the motors M ₁ and M ₂ by 1/3 by the multipliers 261a and 262a, and the current detection values by the adders 261b, 261c and 262b and 262c. _i u1det, i w1det and _{i u2det,} respectively subtracted from _{i w2det,} resulting an adder 261 d, by the output of 262d, a positive phase current of the three-phase removal of the zero-phase component from the current detection value of each motor obtain.

In order to obtain the current amplitude of the positive phase, the above-described three-phase positive phase currents are sequentially added to the three-phase / two-phase converters 261e and 262e and the coordinate converters 261f and 262f, and the current value i in the dq coordinate system is determined. _d1 , i _q1 and i _d2 , i _q2 are obtained. Next, by obtaining the square root of the square sum of these current values by the amplitude calculators 261g and 262g, the positive phase current amplitudes I ₁ and I ₂ of the motors M ₁ and M ₂ can be obtained.

As described above, according to the fourth embodiment, the inverter DC bus voltage can be arbitrarily boosted, and the sum of the positive phase component and the zero phase component of each motor current can be minimized. Therefore, the motors M ₁ and M ₂ can be minimized. It is possible to minimize the temperature rise.

  In each of the above-described embodiments, various calculations are performed using the detected current value of the positive phase of the motor, but a positive phase current command value or a torque command value may be used instead.

It is a circuit block diagram which shows 1st Embodiment of this invention. FIG. 2 is a zero-phase equivalent circuit diagram of the motor drive device in FIG. 1. FIG. 2 is an equivalent circuit diagram for the positive phase of the motor driving device in FIG. 1. FIG. 2 is a circuit configuration diagram for generating a gate signal for each switching element of FIG. 1. It is a block diagram which shows the internal structure of the control circuit in FIG. FIG. 6 is a block diagram illustrating an internal configuration of a boost operation control unit in FIG. 5. It is a circuit block diagram which shows 2nd Embodiment of this invention. It is explanatory drawing of the zero phase current distribution factor k in 2nd Embodiment. It is a circuit block diagram which shows 3rd Embodiment of this invention. It is explanatory drawing of the zero phase current distribution factor k in 4th Embodiment of this invention. It is a block diagram which shows the calculation means of the positive phase current amplitude in 4th Embodiment.

Explanation of symbols

101, 101A, 101B, 102, 102A, 102B Motor drive devices 111, 112, 121, 122 Current detection means 130 Voltage detection means 200, 200A, 200B Control circuit 200a Microcomputer 200b Storage devices 210, 211, 212 Adders 220, 221 , 222 PWM generator 231, 232 Motor controller 240 Zero phase current distribution controller 250 Boost operation controller 251, 254, 255, 257 Adder 252, 256, 258 PI controller 253 Multiplier 261 a, 262 a Multiplier 261 b, 261c, 261d, 262b, 262c, 262d adder 261e, 262e 3-phase / 2-phase converter 261 f, 262f coordinate converter 261 g, 262 g amplitude calculator _C 1, _{C 2} smoothing capacitor _INV 1, INV ₂ inverter _T 11 through T _{1 6} , T _{21 to} T ₂₆ , T _Z1 , T _Z2 semiconductor switching element M ₁ , M ₂ motor L ₁ reactance BATT battery NTC ₁ , NTC ₂ temperature detection means

Claims (7)

A multiphase voltage source inverter; power storage means connected to the DC input terminal of the inverter; a motor in which a stator winding is star-connected to the AC output terminal of the inverter; and a neutral point of the stator winding And a power supply connected between one of the DC buses of the inverter and a plurality of motor drive devices having a boosting function for boosting the voltage of the power supply and supplying the boosted voltage to the power storage means In the motor drive system provided,
A motor drive system characterized in that the neutral points of the motors are connected in common and the positive side and the negative side of the DC bus are connected in common. In the motor drive system according to claim 1,
A motor drive system comprising control means for determining a distribution ratio of a zero-phase current flowing through the neutral point of each motor by a boost operation of each motor drive device. In the motor drive system according to claim 2,
The motor drive system characterized in that the control means determines the distribution ratio using a winding resistance value of the motor of each motor drive device. In the motor drive system according to claim 2,
The motor drive system characterized in that the control means determines the distribution ratio using the temperature of the motor of each motor drive device. In the motor drive system according to claim 2,
The motor drive system characterized in that the control means determines the distribution ratio using the temperature of a semiconductor switching element constituting the inverter of each motor drive device. In the motor drive system according to claim 2,
The motor drive system characterized in that the control means determines the distribution ratio using a positive phase current flowing through the motor of each motor drive device. In the motor drive system according to any one of claims 1 to 6,
The step-up function of each motor drive device is a function that turns on all semiconductor switching elements of the upper arm or lower arm of the inverter to output a zero-phase voltage and operates the inverter as a step-up chopper. Motor drive system.

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