JP2008125233A - Apparatus and method for driving motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably drive a multipolar motor used in a large electric automobile, a hybrid automobile or the like by a system constituted at low cost. <P>SOLUTION: In a three-phase eight-pole alternating current motor, coils of phases U, V, and W of eight poles of a stator are divided into four coil groups of a first coil group C1, a second coil group C2, a third coil group C3, and a fourth coil group C4 by two poles. U, V, and W power lines are made independent with respect to each coil group C1, C2, C3 and C4, and connected to four inverters of a first inverter I1, a second inverter I2, a third inverter I3, and a fourth inverter I4. These inverters I1 to I4 are operated by one control computer S in synchronization. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving device and a driving method for an electric motor used as a prime mover of an electric vehicle, a hybrid vehicle, and the like.

When an automobile with a relatively large total vehicle weight, such as a large truck, is converted into an electric vehicle or a hybrid vehicle, it is necessary to control a large electric motor corresponding to the total vehicle weight.
Essentially, a large electric motor is required to be supplied with necessary power by a large inverter commensurate with the output of the electric motor.
However, in order to manufacture a high output inverter, a special semiconductor element such as a large IGBT is required, and the number of manufacturing is small, and the price increases. Although the acquisition itself is difficult, it takes too much time to replenish.

  Assuming, for example, a 200 KW (kilowatt) class motor that operates at 500 V (volts) as a large motor required for a large vehicle, in order to operate this by a normal method, a simple calculation requires a withstand voltage of 500 V, An allowable current of 400 A (ampere) is required. However, in reality, it must be set to withstand a surge voltage and withstand an instantaneous overload.

  In consideration of their practicality, an approximate output voltage of 1200 V and a method of using a direct current by PWM (pulse width modulation) technique as an alternating current requires 400 A as an alternating current average value including a region where energization is restricted. The instantaneous allowable energization amount is required to be at least 1500A. Furthermore, when trying to control high voltages and large currents in a batch, countermeasures against noise are needed.

There has been an attempt to output a large current from a plurality of inverters by connecting the output of the inverter in parallel at the output terminal portion, but this has not been realized. In this method, the IGBTs are not completely synchronized with each other, and in many cases, there is a high possibility that they will be damaged as soon as they are energized.
An apparatus that drives a single electric motor using a plurality of inverters is disclosed in Patent Document 1.

In Patent Document 1, as a vehicle electric motor, a pair of three-phase armature windings wound separately in adjacent slots of a stator are attached, and an inverter is connected to each of the pair of windings. When one motor is driven and one inverter fails, the operation of the failed inverter is stopped, and the amount of current supplied from the remaining inverter is doubled to perform fail-safe operation.
JP 2003-174790 A

However, the one described in Patent Document 1 is a countermeasure against failure and does not deal with an increase in size.
If it is intended to increase the output with this method, it is a configuration in which a plurality of independent in-phase windings are arranged per pole, so if the number of inverters increases to three and four, three A U-winding for the eye or for the fourth unit is required, and the V-phase and W-phase are also required in the same way, so the number of slots and teeth is doubled.

When the slot size changes, the wire diameter and the number of turns of the winding also change, and accordingly, the inverter characteristics and control characteristics need to be changed.
The present invention has been made paying attention to such a conventional problem, and an object of the present invention is to enable a large motor to be operated using a plurality of medium and small inverters.

Therefore, the invention according to the present invention is
A multi-pole motor in which the coils of each phase of the stator are divided into n (≧ 2) coil groups in the circumferential direction of the stator, and the power lines are separated for each coil group;
N inverters respectively connected to the power lines of the corresponding coil group of each phase of the motor;
Control means for driving the electric motor by operating the n inverters synchronously;
It is characterized by including.

In this way, it is only necessary to divide the stator coil group and separate the power lines from the conventional multi-pole motor driven by one inverter. On the other hand, since power transmission or necessary control is executed, parallel operation is possible while avoiding interference with inverters in charge of other coil groups.
In addition, since the large and small motors can be operated by the medium and small inverters applied to the medium and small vehicles, the mass productivity is increased and the cost is naturally reduced. It is also advantageous in terms of obtaining and supplying parts.

For example, as the stator coil of an electric motor, normally, 2 poles, 4 poles, 6 poles, 8 poles, 12 poles, 16 poles, etc. are frequently used. In an electric motor used for a large electric vehicle, a multipolar machine having about 8 poles to 16 poles is used in view of its rotational speed region and torque.
A first embodiment in which the present invention is applied to a three-phase eight-pole AC motor will be described below with reference to the drawings.

FIG. 1 is a so-called DC brushless type winding in which the outline circuit configuration (the circumferential direction is expanded in the lateral direction) is shown, and the number of coils for generating two poles is reduced by one set of U, V, and W three-phase coils. 3 phases × 8/2 poles = 12 sets of coils.
Here, in the case of concentrated winding, which is the simplest form, a total of three U / V / W three-phase units, one for each phase, so a minimum of 12 coils are required for the entire stator. Moreover, in order to obtain a smooth driving | operation, when it is set as a lap winding or a wave winding, it is comprised with the coil of the integral multiple.

In this embodiment, the 8-pole U, V, and W phase coils of the stator are arranged in the circumferential direction of the stator, with 2 poles generated by a set of U, V, and W 3-phase coils that are the smallest unit. The first group coil C1, the second group coil C2, the third group coil C3, and the fourth group coil C4 are divided.
Then, the U, V, and W power lines are independently connected to a terminal box (not shown) for each of the coils C1, C2, C3, and C4 of the first group to the fourth group.
One inverter I1, I2, I3, and I4 is connected to each of the coils C1, C2, C3, and C4 of the first group to the fourth group.

Four first inverters I1, second inverter I2, third inverter I3, and fourth inverter I4 are operated in synchronism by one control computer S.
Usually, there is a mass-produced IGBT element having a 1200V withstand voltage and an allowable current of 300A. If this is used, an inverter of about 500V · 110A, that is, a 55 KW class can be manufactured. The 55KW class inverter is suitable for driving and controlling medium and small vehicles up to a total vehicle weight of around 3 tons. However, when mass production is assumed, it is located in the central area of large-scale production.

If the four inverters are connected to the stator configured as described above, the electric output is set to 220 KW, and the electric motor is considered in terms of their efficiency, by the set of the motor and the four inverters. Although it is less than the output, it is possible to output motive power almost corresponding to the capacity of the electric motor.
The four PWM inverters I1, I2, I3, and I4 are supplied with the same PWM signal from the control computer S divided into four sets. That is, the four inverters I1, I2, I3, and I4 are simultaneously operated in the same pattern.

In the stator of the 8-pole motor, the mechanical (rotor rotation) angle is shifted by 90 ° for every 360 ° of electrical angle. Generates rotational force while transferring control.
By configuring as described above, it is possible to supply completely independent signals to the respective inverters I1, I2, I3, and I4 while completely synchronizing the input signals of the inverters I1, I2, I3, and I4. Each of the inverters I1, I2, I3, and I4 magnetizes the stator teeth by an electrically insulated and independent stator coil. The stator coils are divided into appropriate “groups” and are energized and magnetized in complete synchronization with other groups while being insulated and independent.

For example, as shown in FIG. 1, when a peak current flows into the U phase, the U phase (the teeth at the winding position) is magnetized to the N pole. At that time, since a medium current flows in the opposite direction between the V phase and the W phase, an S pole is generated near the middle of the V phase and the W phase.
Next, the W-phase current peaks and the W-phase is magnetized to the S-pole, and an N-pole is generated near the middle of the U-phase and the V-phase.

Similarly, when the V phase is magnetized to the N pole, the S pole is generated near the middle of the W phase and the U phase, and when the U phase is magnetized to the S pole, the N pole is located near the middle of the V phase and the W phase. When the W phase is magnetized to the N pole, the S pole is generated near the middle of the U phase and the V phase. When the V phase is magnetized to the S pole, the N pole is generated near the middle of the W phase and the U phase. .
Thus, as the AC power phase advances, the magnetic poles of the stator rotate and the rotor rotates.

In the above figure, the method of dividing and managing the 8-pole stator coil into 4 groups is shown, but it can be divided into 4 groups by dividing every 4 poles.
In FIG. 1, the U, V, and W phases are shown as star connections, but it is needless to say that the present invention can also be applied to delta connections.
In this way, it is possible to configure an electric motor drive device composed of a large-sized inverter / motor set almost indefinitely by using semiconductor elements of general and mass-produced models. Small cars have one inverter as before, medium cars have two inverters and a motor with a corresponding stator coil, and large cars have four or more identical inverters and corresponding motors. A prime mover unit may be used. In this way, since inverters of the same standard are mass-produced and used according to the model of the automobile, there are advantages in terms of cost and parts management.

In the case of a stator that generates two poles with a set of three-phase coils of U, V, and W as described above, a set of three phases of U, V, and W is used in an 8-pole motor as described above. As a minimum unit, it is divided into a maximum of 8/2 = 4 coil groups.
On the other hand, in the case of a stator configured to generate one pole with a set of three-phase coils of U, V, and W, the maximum number of coils is the same as the number of motor poles (eight in the case of eight poles). Can be divided into groups.

FIG. 2 shows an embodiment applied to an 8-pole motor that generates one pole with a set of coils of U, V, and W phases.
The stator of this electric motor is provided with a total of 24 coils in concentrated winding (an integral multiple of lap winding and wave winding), and a total of 6 coils of 2 sets of U, V, and W 3 phases, with N and S2 poles. It is formed.
In this embodiment, these 24 coils are divided in the circumferential direction of the stator by the minimum unit of one set of U, V, and W phases, and each power line is connected to the first to eighth inverters. To do.

The operation will be described with reference to the drawing.
a. When the N pole is generated in the first coil (shown below the coil No. 1 in FIG. 2; the same applies to the other) by the U-phase power supplied from the first inverter (the N pole or the S pole is simply When the magnetic field is generated, it means that the magnetic force reaches a peak value). Due to the U-phase power from the second inverter, a current in the direction opposite to that of the first coil flows through the fourth coil to generate the S pole. .

At the same time, due to the W-phase power supply from the first inverter, a current flows in the second coil in the same direction as the first coil and becomes a medium N-pole. , Current flows in the opposite direction to the first coil, and becomes an intermediate S pole.
b. When the phase of the AC power supplied from the inverter is advanced and the N pole is generated in the second coil, the W coil from the second inverter is supplied with the W phase, and the fifth coil in which the reverse current direction flows is the S pole. Is generated.

At the same time, a current flows through the third coil in the same direction as the second coil and becomes a medium N pole, and a current flows through the fourth coil in a direction opposite to the second coil and a medium S pole. It becomes.
c. Similarly, when the N pole is generated in the third coil, the S pole is generated in the sixth coil whose current direction is opposite.
At the same time, a current flows through the fourth coil in the same direction as that of the third coil, so that it becomes a medium N pole.

At the same time, a current flows through the fifth coil in the direction opposite to that of the third coil, so that it becomes an intermediate S pole.
d. When the N pole is generated in the fourth coil by supplying power from the second inverter to the U phase, the S pole is generated in the seventh coil whose current direction is reversed by supplying the U phase power from the third inverter. To do.
At the same time, due to the power supply to the W phase, a current flows through the fifth coil in the same direction as the fourth coil and becomes a medium N pole, and the power supply to the V phase causes the first coil to pass through the first coil. A current flows in the opposite direction to the coil, resulting in an intermediate S pole.

e. When the N pole is generated in the fifth coil, the S pole is generated in the eighth coil whose current direction is opposite.
At the same time, a current flows through the sixth coil in the same direction as the fifth coil and becomes a medium N pole, and a current flows through the seventh coil in a direction opposite to that of the fifth coil and becomes a medium S pole. .
f. Similarly, when the N pole is generated in the sixth coil, the S pole is generated in the ninth coil whose current direction is opposite.

At the same time, a current flows through the seventh coil in the same direction as the sixth coil and becomes a medium N pole, and a current flows through the eighth coil in a direction opposite to that of the sixth coil and becomes a medium S pole. .
As mentioned above, although the change of the magnetic pole from the 1st coil to the 9th coil was shown, since the same alternating current power of each phase was supplied synchronously from all the inverters, the same magnetic pole change was produced, and the 1st-1st The cycle of a to f is repeated with all 24 coils to generate a rotating magnetic field in which the magnetic pole rotates.

When selecting the optimum value of the inverter corresponding to the motor output, if the coil wire cross-sectional area when the 8-pole portion is covered by one inverter is 1, the 8-pole portion is equivalent to 8 When operating with an inverter, if the axial length of the stator is the same, the number of coil wires may be substantially the same, and the wire diameter cross-sectional area may be designed to be about 8.
Moreover, although patent document 1 aims at countermeasures against failure, even in the present invention, when one inverter fails, the operation of the inverter can be stopped to cope with it.

In this case, the control computer can also secure the necessary power by increasing the amount of current supplied from the normal inverter other than the failed inverter to the corresponding coil group.
In addition, the control computer C also stops the operation of the inverter connected to the coil group to which the failed inverter is connected and the coil group at the rotationally symmetric position, and the energization amount from the remaining normal inverter to the corresponding coil group fails. An increase correction can be made so that an output equivalent to the previous motor output can be obtained.

  For example, when the first inverter fails, the operation of the first inverter is stopped and the coil group (first to third coils) driven by the first inverter and the coil located on the opposite side with respect to the rotating shaft of the motor The operation of the fifth inverter that drives the group is stopped, and further, the operation of the odd third and seventh inverters is also stopped. To get equivalent output.

  In other words, if the number of poles is sufficiently large, the effect of the failure of one unit is small, but if the number of poles is not so large, the torque generated from each coil group of the stator is reduced by stopping the operation of the failed inverter. The direction becomes non-uniform and the smoothness of rotation is impaired. Therefore, the operation of the inverter connected to the coil group to which the failed inverter is connected and the coil group in the rotationally symmetric position is also stopped, while maintaining the rotational symmetry in the coil group connected to the normal inverter, By increasing and correcting the energization amount of these normal inverters, the output can be secured without impairing the smoothness of rotation.

FIG. 3 shows another embodiment applied to an 8-pole motor that generates one pole with a set of U, V, and W three-phase coils as described above.
In the present embodiment, the stator coil is divided into two coil groups and driven by two inverters.
The coils of each phase of U, V and W are connected in series in the circumferential direction of the stator, and divided into two coil groups.

Specifically, the U-phase first coil, seventh coil, thirteenth coil, and nineteenth coil are connected in series to form a U-phase first group coil, and the fourth coil, the tenth coil, the sixteenth coil, and the twenty-second coil. The coils are connected in series to form a U-phase second group coil.
Similarly, the V-phase third coil, ninth coil, fifteenth coil, and twenty-first coil are connected in series to form a V-phase first group coil, and the sixth coil, the twelfth coil, the eighteenth coil, and the twenty-fourth coil are connected. A V-phase second group coil is connected in series.

Similarly, a W-phase second coil, an eighth coil, a fourteenth coil, and a twentieth coil are connected in series to form a W-phase first group coil, and a fifth coil, an eleventh coil, a seventeenth coil, and a twenty-third coil are connected in series. Connected to form a W-phase second group coil.
Then, the power lines of the U-phase first group coil, the V-phase first group coil, and the W-phase first group coil are connected to the first inverter, the U-phase second group coil, the V-phase second group coil, and the W-phase first coil. The power line of the second group coil is connected to the second inverter.

Hereinafter, the operation of the present embodiment will be described.
a. When the N pole is generated in the (first, seventh, thirteenth, nineteenth coils) by the U-phase power supplied from the first inverter, the U-phase power is generated by the U-phase power from the second inverter. In the second group coil (fourth, tenth, sixteenth, and twenty-second coils), a current in the direction opposite to that of the U-phase first group coil flows to generate the S pole.

At the same time, the W-phase power supply from the first inverter causes the W-phase first group coil (second, eighth, fourteenth, and twentieth coils) to have a current in the same direction as the U-phase first group coil. The current becomes a medium N pole, and the power supply to the V phase also causes the V phase first group coil (third, ninth, fifteenth, and twenty-first coils) to be opposite to the U phase first group coil. A current flows in the direction and becomes a middle S pole.
b. When the phase of the AC power supplied from the inverter advances and N poles are generated in the W-phase first group coil (second, eighth, fourteenth, and twentieth coils), the W-phase from the second inverter With power supply, a current direction opposite to that of the W-phase first group coil flows through the W-phase second group coil (fifth, eleventh, seventeenth, and twenty-third coils) to generate an S pole.

At the same time, a current flows in the V-phase first group coil (third, ninth, fifteenth, and twenty-first coils) in the same direction as the W-phase first group coil, and becomes a medium N pole. A current flows through the phase second group coil (fourth, tenth, sixteenth, and twenty-second coils) in the direction opposite to that of the W-phase first group coil, and becomes a medium S pole.
c. Similarly, when the N pole is generated in the V-phase first group coil (third, ninth, fifteenth, and twenty-first coils), the V-phase second group coil ( In the sixth, twelfth, twelfth, eighteenth and twenty-fourth coils), a current direction opposite to that of the V-phase first group coil flows to generate an S pole.

At the same time, a current flows in the U-phase second group coil (fourth, tenth, sixteenth, and twenty-second coils) in the same direction as the V-phase first group coil, and becomes a medium N pole. A current flows through the phase second group coil (fifth, eleventh, seventeenth, and twenty-third coils) in the direction opposite to that of the V-phase first group coil, and becomes a medium S pole.
d. Similarly, when an N pole is generated in the U-phase second group coil (fourth, tenth, sixteenth, and twenty-second coils) by supplying the U-phase power from the second inverter, the U-phase from the first inverter By supplying power, a current in the direction opposite to that of the U-phase second group coil flows through the U-phase first group coil (first, seventh, thirteenth, and nineteenth coils) to generate the S pole.

At the same time, a current flows through the W-phase second group coil (fifth, eleventh, seventeenth, and twenty-third coils) in the same direction as the U-phase second group coil, resulting in a medium N pole. A current flows through the phase second group coil (sixth, twelfth, eighteenth, and twenty-fourth coils) in the direction opposite to that of the U-phase second group coil, and becomes a medium S pole.
e. When the N pole is generated in the W-phase second group coil (the fifth, eleventh, seventeenth, and twenty-third coils), the W-phase power supply from the second inverter causes the W-phase first group coil (second , 8th, 14th, and 20th coils), a current direction opposite to that of the W-phase second group coil flows to generate an S pole.

At the same time, a current flows in the V-phase second group coil (sixth, twelfth, eighteenth, and twenty-fourth coils) in the same direction as the W-phase second group coil, and becomes a medium N pole. A current flows through the phase first group coil (first, seventh, thirteenth, and nineteenth coils) in the direction opposite to that of the W phase second group coil, and has a middle S pole.
f. Similarly, when the N pole is generated in the V-phase second group coil (sixth, twelfth, eighteenth, and twenty-fourth coils), the V-phase power supply from the second inverter causes the V-phase first group coil ( In the third, ninth, fifteenth, and twenty-first coils), a current direction opposite to that of the V-phase first group coil flows to generate an S pole.

At the same time, a current flows through the U-phase first group coil (first, seventh, thirteenth, and nineteenth coils) in the same direction as the V-phase second group coil, and becomes a medium N pole. A current flows through the phase first group coil (second, eighth, fourteenth, and twentieth coils) in the direction opposite to that of the V phase second group coil, and has a middle S pole.
The cycle of a to f is repeated to generate a rotating magnetic field in which the magnetic pole rotates.

Further, in the present embodiment, when one inverter, for example, the first inverter fails, the operation of the first inverter is stopped, and the energization amount of only the second inverter is doubled, so that they are substantially equivalent. Since each of the coils of each phase is connected in series and divided into two, the rotation object is maintained even in the operation of only one coil group, and smooth operation can be performed.
Moreover, in the said embodiment, although each coil in the 1st group coil of each phase of U, V, and W and each coil in the 2nd group coil were connected in series, respectively, the electric power introduction side ends of each of these coils Are connected in parallel, and the U, V, and W power lines of the first group coil and the second group coil that are one by one may be connected to the first inverter and the second inverter, respectively. It has a function.

  2 and 3 can also be considered as diagrams showing an embodiment applied to a 16-pole motor that generates 2 poles with a set of U, V, and W 3-phase coils as in the first embodiment.

The figure which shows the structure of the 1st Embodiment of this invention. The figure which shows the structure of the 2nd Embodiment of this invention. The figure which shows the structure of the 3rd Embodiment of this invention.

Explanation of symbols

C1 first group coil C2 second group coil C3 third group coil C4 fourth group coil I1 first inverter I2 second inverter I3 third inverter I4 fourth inverter S control computer

Claims (6)

A multi-pole motor in which the coils of each phase of the stator are divided into n (≧ 2) coil groups in the circumferential direction of the stator, and the power lines are separated for each coil group;
N inverters respectively connected to the power lines of the corresponding coil group of each phase of the motor;
Control means for driving the electric motor by operating the n inverters synchronously;
An electric motor drive device comprising:   The electric motor drive device according to claim 1, wherein the electric motor is a three-phase electric motor, and is divided with a set of coils of U, V, W3 phases as a minimum unit.   3. The electric motor drive device according to claim 1, wherein when one inverter fails, the control unit stops the operation of the failed inverter. 4.   4. The electric motor drive device according to claim 3, wherein the control means corrects an increase in an energization amount from an inverter other than the failed inverter to a corresponding coil group.   The control means also stops the operation of the inverter connected to the coil group at the rotationally symmetric position with the coil group to which the failed inverter is connected, and the electric current from the remaining inverter to the corresponding coil group is reduced to the electric motor before the failure. The motor driving apparatus according to claim 4, wherein the increase correction is performed so that an output equivalent to the output is obtained. The coils of each phase of the stator in the multipolar motor are divided into n (≧ 2) coil groups in the circumferential direction of the stator, and the power lines are separated for each coil group,
n inverters are respectively connected to the power lines of the corresponding coil groups of each phase of the motor,
A motor driving method for driving an electric motor by operating the n inverters in synchronization.

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