JPH09149689A - Operation controller for pole change motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate fluctuation of torque even if the number of poles of an induction motor is changed under heavy load. SOLUTION: An inverter 2 being fed with a DC voltage from a battery 3 operates an induction motor(IM) 1 with four poles in low speed operation region and with two poles in high speed operation region by controlling the phase and frequency of output voltage. A regeneration bypass circuit 11 feeds the voltage of battery 3 to the inverter 2 or feeds the regenerated voltage from inverter 2 to the battery 3. A step-up chopper circuit 10 feeds a step-up voltage to the inverter 2 when the number of pole is switched under heavy load. This circuitry eliminates fluctuation of torque at the time of switching the number of pole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for variable speed control of an induction motor using an inverter and enabling a wide range of constant output operation by switching the number of poles. It was devised to suppress it.

[0002]

2. Description of the Related Art Frequency control using an inverter as a power source is often employed for variable speed control of an induction motor. The maximum torque characteristic at this time is a constant torque characteristic in the range in which the voltage supplied from the inverter can be increased in proportion to the increase in speed (or frequency), as indicated by the characteristic T'in the broken line in FIG. Above that, the torque T'decreases due to the 1 / f ² curve inversely proportional to the square of the frequency f due to the limitation of the power supply voltage V. On the other hand, in an electric vehicle or the like that uses an induction motor as a drive source, the required torque characteristic of the load becomes a constant output range when the speed exceeds the constant torque range as shown by the characteristic T of the solid line in FIG. The torque T decreases with a 1 / f curve that is inversely proportional to the increase of f. Therefore, the output torque is limited by the maximum torque characteristic T'at a rotation speed higher than the frequency af at the intersection of the maximum torque characteristic T'and the required torque characteristic T of the load. In general, a is an arbitrary number greater than 2, but it is satisfied if it is 1 or more.

When the induction motor is operated in the constant output range,
Although the load torque decreases as the speed becomes higher, the torque is limited by the maximum torque characteristic of the induction motor, which may cause torque shortage depending on the load. In order to eliminate this torque shortage, the applicant of the present application has adopted a stator winding structure in an induction motor as a winding structure equivalent to having three N-phase windings (N is an even number), and By controlling the phase and frequency of the voltage with an inverter, a technique has been developed to drive the induction motor with 2N poles in the low speed operation region and drive it with the N poles in the high speed operation region. ) And (2) ~
Filed as shown in (4).

(1) Analysis of pole number switching induction motor for electric vehicle by six-phase absolute conversion rotation dq axis: Mizuno et al., Institute of Electrical Engineers, Rotating Machinery Research Society, announced on October 3, 1994. (2) Japanese Patent Application No. 6-131511 (filed on June 14, 1994) "Induction motor and its operation control device". (3) Japanese Patent Application No. 6-307648 (December 12, 1994)
(Japanese application) "Operation control device for pole change motor". (4) Japanese Patent Application No. 7-33536 (filed on February 22, 1995) "Operation control device for pole number switching motor".

For example, for an induction motor having a 6-phase stator winding structure, by controlling the phase and frequency of the voltage supplied by an inverter, it is driven with 2 poles in the low speed operation region and 4 in the high speed operation region. It can be driven with a pole. At this time, as shown in FIG. 5, the maximum torque during the 2-pole operation is about twice the maximum torque during the 4-pole operation.
Therefore, when the number of poles is switched at the number of rotations as shown in FIG. 5, the maximum torque of the induction motor can be afforded with respect to the required torque T of the load, and a wider range of constants can be obtained compared to the case where only four poles are operated. Output operation becomes possible. In addition, when operating at the same number of revolutions, the frequency during 2-pole operation is approximately 1/2 of the frequency during 4-pole operation, so switching to 2-pole operation reduces loss in the induction motor and reduces The controllability of can be improved.

Winding of 6-phase stator winding structure of induction motor
The arrangement can be represented as in FIG. However, each winding
Is almost full-pitch winding at 120 ° phase band for 4 poles and 2 poles
On the other hand, it is almost half of the magnetic pole pitch in the 60 ° phase band.
It is assumed that the tape has been rolled. Therefore,
In order to have two poles, the magnetic flux that makes the opposite windings different poles is created.
Voltage should be applied so that the voltage of each phase is V_a1, V_b1, V
_c1, V_d1, V_e1, V_f1As shown in the following [Equation 1]
I just need. Also, in order to have four poles, the windings facing each other must have the same pole.
It suffices to add a voltage to create a magnetic flux that
V_a2, V_b2, V _c2, V_d2, V_e2, V_f2Is shown as [number
2]. However, V_1m, Ω₁, Φ₁Is
It is the maximum value of phase voltage, angular frequency, and phase angle during 2-pole operation.
V_2m, Ω_Two, Φ_TwoIs the maximum phase voltage and angular frequency during 4-pole operation
Number and phase angle.

[0007]

(Equation 1)

[0008]

(Equation 2)

In the 6-phase winding shown in FIG. 6, a rotating coordinate axis of 2 poles (d ₁ -q ₁ axis) and a rotating coordinate axis of 4 poles (double angle d ₂
-Q ₂ axes) were prepared and the coordinate axes based on the dq axes (two axes) were examined. As a result, the following equations [Equation 3] and [Equation 4] were obtained.

[0010]

(Equation 3)

[0011]

(Equation 4)

In the equations [3] and [4], the subscript 1 indicates a 2-pole machine, the subscript 2 indicates a 4-pole machine, and the subscript s indicates a stator (stat).
or) winding, and the subscript r represents the dq axis relating to the rotor winding. In the formula, R _s1 : primary resistance, L _s1 : primary self-inductance, M _sr1 : mutual inductance, R _r1 : secondary resistance, L
_{r1 is the} secondary self-inductance, R _{m1 is the} iron loss resistance, and there are four pole constants, R _{s2 is the} primary resistance, L _{s2 is the} primary self-inductance, M _{sr2 is the} mutual inductance, R
_r2 : secondary resistance, L _r2 : secondary self-inductance, R _m2 :
Iron loss resistance.

In the above [Equation 3], the armature winding side voltage V
_ds1, in wherein the V _qs1, considering the time that is performed vector _{control, I dr1 = 0, I qr1} = (- M sr1
/ L _r1 ) · I _qs1 holds.

Further, in the present invention, iron loss R _m1 = R _m2 =
Due to the negligible as 0, V _ds1, V _qs1 above is represented by the following formula [Formula 5].

[0015]

(Equation 5)

As a result, V is given by the following equations [Equation 6] and [Equation 7].
_{It suffices} to control _ds1 and V _qs1 (armature side).

[0017]

(Equation 6)

[0018]

(Equation 7)

[0019] Finally, the vector control calculation, obtains a torque command from the speed command to obtain the current command I _ds1, I _qs1 shown from the torque command to the equation (3), the voltage command indicating a current command in the 6] seeking V _ds1, V _qs1, seeking phase voltage indicating this voltage command V _ds1, V _qs1 in Expression 1, it is two-pole operation by supplying the phase voltages to the induction motor. Similarly, the vector control operation
A torque command is obtained from the speed command, current commands I _ds2 and I _qs2 shown in [ _Formula 4] are obtained from this torque command, voltage commands V _ds2 and V _qs2 shown in [ _Formula 7] are obtained from this current command, and this voltage is obtained. Four-pole operation can be performed by _obtaining each phase voltage shown in [ _Equation 2] from the commands V _ds2 and V _qs2 and supplying each phase voltage to the induction motor.

The prior art of the operation control device of the pole number switching motor, which is applied to the electric vehicle, is the technology for switching the number of poles by switching the phase and frequency of the voltage of each phase winding of the induction motor as described above. Will be described with reference to FIG. 7.

In FIG. 7, the induction motor 1 has a six-phase stator winding structure or a stator winding structure in which two sets of three-phase windings are combined. The inverter device 2 includes one 6
It is composed of a phase inverter or two 3-phase inverters. The battery 3 supplies a DC voltage to the inverter device 2 via the DC capacitor 4,
Supplies a voltage whose phase and frequency are controlled to each phase winding of the induction motor 1. This causes the induction motor 1 to rotate.

The rotation speed sensor 5 is directly connected to the rotor of the induction motor 1, and the rotation speed (rotation speed) of the induction motor 1.
A motor rotation speed signal a corresponding to the above is output. Current detector 6
Detects the current of each phase supplied from the inverter device 2 to the induction motor 1 and outputs the motor current signal b corresponding to the detected current value.

In addition to the motor speed signal a and the motor current signal b, an accelerator opening signal c is input to the system controller 7. Then, the system control device 7 performs the following (a), (b) and (c) according to the value of the accelerator opening signal c.
An inverter drive signal d for operating the inverter device 2 to perform the operation (d) is sent to the inverter device 2.

(B) As shown in FIG. 2, the inverter device 2 controls the phase and frequency of each phase voltage supplied to the induction motor 1 so that the induction motor 1 operates in four poles in the low speed operation region. Moreover, during the 4-pole operation, the supply voltage frequency is increased / decreased according to the increase / decrease of the accelerator opening signal c to increase / decrease the rotation speed of the induction motor 1.

(B) As shown in FIG. 2, the phase and frequency of each phase voltage supplied to the induction motor 1 are controlled by the inverter device 2 so that the induction motor 1 operates in two poles in the high speed operation region. Moreover, during the two-pole operation, the supply voltage frequency is increased / decreased in accordance with the increase / decrease in the accelerator opening signal c to increase / decrease the rotation speed of the induction motor 1.

(C) As shown in FIG. 2, when the motor rotation speed rises from the low speed rotation range and exceeds the motor rotation speed n ₂ , the 4-pole operation is switched to the 2-pole operation. That is, the voltage supplied to the induction motor 1 is switched from the 4-pole operation voltage to the 2-pole operation voltage.

(D) As shown in FIG. 2, when the motor rotation speed falls from the high speed rotation region and becomes smaller than the motor rotation speed n ₁ , the two-pole operation is switched to the four-pole operation. That is, the voltage supplied to the induction motor 1 is switched from the two-pole operation voltage to the four-pole operation voltage.

After all, in the conventional operation control device for the pole number switching motor shown in FIG. 7, the induction motor 1 is operated with four poles in the low speed operation region and with two poles in the high speed operation region, and the number of poles is switched by the hysteresis. With the characteristics, the rotation speed of the induction motor 1 is controlled (speed control) according to the accelerator opening signal c. The number of poles switching period is 0.
It is about 7 to 1 second, and in this pole number switching period, the 4-pole operation voltage and the 2-pole operation voltage are output from the inverter device 2. Therefore, during the pole number switching period, the output voltage value of the inverter device 2 tends to increase with the inverter output voltage upper limit value as the upper limit. The inverter output voltage upper limit value is defined by the voltage of the battery 3 and the performance of the inverter device 2.

When the load is applied (when the output power of the inverter device is small), the output voltage value of the inverter device 2 during the pole number switching period is larger than the output voltage value during the period other than the pole number switching period. It does not exceed the output voltage upper limit. Therefore, torque fluctuation (reduction of motor torque) hardly occurs during the switching period. That is,
Even if the four-pole operation voltage and the two-pole operation voltage are increased and output so as not to cause torque fluctuation, the combined output voltage value is smaller than the inverter output voltage upper limit value, and torque fluctuation does not occur.

[0030]

By the way, at the time of heavy load (when the output power of the inverter device is large), the output voltage of the inverter device 2 is higher than the inverter output voltage upper limit value even during the period other than the pole number switching period. Since the output voltage is close to, the output voltage is regulated by the inverter output voltage upper limit value and the inverter output voltage value cannot increase during the number of pole switching period even if an attempt is made to increase the output voltage so as not to cause torque shortage. . That is, the output voltage cannot exceed the inverter output voltage upper limit value, and the upper limit value of the 4-pole operation voltage or the 2-pole operation voltage at this time is also limited, resulting in insufficient torque for heavy loads. Will end up. Therefore, as shown in the area Z in FIG. 8, the torque T ′ of the induction motor 1 is temporarily reduced during the pole number switching period under heavy load.

Torque reduction as described above (torque fluctuation)
When this occurs, the driver of the electric vehicle feels uncomfortable when switching the number of poles.

In view of the above-mentioned prior art, the present invention provides an operation control device for a pole number switching motor in which torque reduction does not occur even when the pole number is switched under heavy load.

[0033]

DISCLOSURE OF THE INVENTION The present invention for solving the above-mentioned problems is an induction motor having a stator winding structure equivalent to having three N-phase windings (N is an even number), and this induction motor. The speed of the induction motor is controlled by changing the voltage frequency applied to the induction motor, and the phase and frequency of the voltage of each phase winding are controlled to drive the induction motor with a pole number of 2N in the low speed operation range to drive the high speed operation range. Then, the inverter device is driven by setting the number of poles of the induction motor to N, a direct current voltage source for supplying a direct current voltage to the inverter device, a semiconductor switch and a diode, and between the inverter device and the direct current power source. A regenerative current bypass circuit that is connected and has a function of supplying a voltage from a DC voltage source to an inverter device and a function of regenerating a voltage from an inverter device to a DC voltage source, A boost chopper circuit configured by an actuator and a semiconductor switch and connected between the inverter device and the DC power supply and having a function of supplying a boosted voltage to the inverter device, the regenerative current bypass circuit, and the booster circuit. It has a control device for controlling so as to exert and stop each function of the chopper circuit, and this control device, when the operating region of the induction motor changes from the low speed operating region to the high speed operating region at the time of heavy load, and When the operating region of the induction motor changes from the high speed operating region to the low speed operating region under heavy load, control is performed so that the boosted voltage supply function by the booster chopper circuit is exerted, and voltage supply by the regenerative current bypass circuit is performed. Control to stop the voltage regeneration function while exerting the function, and further,
During light load operation, and when the induction motor is operated in a rotation speed region that is not the rotation speed region for switching the number of poles, the boost voltage supply function by the boost chopper circuit is controlled to be stopped, It is characterized in that control is performed so that the voltage supply function and the voltage regeneration function by the regenerative current bypass circuit are exhibited.

Further, according to the present invention, an induction motor having a stator winding structure equivalent to having three N-phase windings (N is an even number) and a voltage frequency applied to the induction motor are changed. By controlling the speed of the induction motor and controlling the phase and frequency of the voltage of each phase winding, the induction motor is driven with a pole number of 2N in the low speed operation area and the induction motor pole is set with N in the high speed operation area. An inverter device to be driven, a DC voltage source for supplying a DC voltage to the inverter device, a flywheel, an AC motor connected to the flywheel, a DC voltage generated by the DC voltage source and a regenerative voltage generated by the inverter device. A function of receiving the AC motor to perform a power running operation and a function of the regenerative operation of converting the regenerative voltage of the AC motor into DC and supplying the DC voltage to the inverter device. Has an energy storage device consisting of an AC motor inverter device, and a control device for controlling or AC motor inverter apparatus of the energy storage device to the regenerative operation or the power running to this control device,
When the operating range of the induction motor changes from the low speed operating range to the high speed operating range when the load is heavy, and when the operating range of the induction motor changes from the high speed operating range to the low speed operating range when the load is heavy, The inverter device for the AC motor is controlled to perform a regenerative operation, and further during light load operation,
In addition, when the induction motor is operated in a rotation speed region other than the rotation speed region in which the number of poles is switched, the inverter device for AC motor is controlled to perform a power running operation.

[0035]

Embodiments of the present invention will be described below. The parts performing the same functions as those of the prior art are denoted by the same reference numerals, and overlapping description will be omitted.

FIG. 1 shows a first embodiment of the present invention.
In the present embodiment, the boost chopper circuit 10 and the regenerative current bypass circuit 11 are connected between the inverter device 2 and the battery 3. The boost chopper circuit 10 is composed of a reactor L ₁ , a semiconductor switch S ₁ and a diode D ₁ , and the regenerative current bypass circuit 11 is composed of semiconductor switches S ₂ and S ₃ and a diode D ₂ . The semiconductor switch S ₂ and the diode D ₂ are integrated into a power module and the semiconductor switch S ₃
It may be composed of a power module integrated with a diode D _1. Further, as described later, since the reactor L ₁ and the semiconductor switch S ₁ is small only be used utilization short, reactor L ₁ and the semiconductor switch S
₁ uses a small current capacity designed by short-time rating.

The voltage detector 12 is connected in parallel to the DC capacitor 4, detects the terminal voltage of the DC capacitor 4 (which is equal to the voltage input to the inverter device 2), and indicates the detected voltage value. The signal e is sent to the system controller 7a. The system control device 7a sends an inverter drive signal d to the inverter device 2 so as to perform the operations of (a), (b), (c), and (d) as in the prior art shown in FIG. The switching of the semiconductor switch S ₁ of the boost chopper circuit 10 and the semiconductor switches S ₂ and S ₃ of the regenerative current bypass circuit 11 are controlled at various timings. The configuration and operation of the other parts are the same as those of the conventional technique shown in FIG.

Next, the operation of the boost chopper circuit 10 and the regenerative current bypass circuit 11 in the first embodiment will be described with reference to FIGS. 1 and 2 (1) during normal operation (2) increase in rotation speed Heavy load switching (3) Rotation speed reduction The heavy load switching will be described separately.

(1) First, the operation during normal operation will be described. During normal operation, the value of the accelerator opening signal c is equal to or less than the set value (during light load) because of light load (at this time, the motor speed may be any value).
Or when the motor rotation speed is less than or equal to the rotation speed n ₁₁ or greater than or equal to the rotation speed n ₂₂ (at this time, the load may have any value).

During normal operation, the system controller 7a
Turns the semiconductor switches S ₂ and S ₃ ON (conducting) and turns the semiconductor switch S ₁ OFF (cutoff). By doing so, the boost chopper circuit 10 does not operate, and no current flows in the reactor L ₁ . The current of the battery 3 is the semiconductor switch S ₂ and the diode D _1.
Is supplied to the inverter device 2 through the power supply circuit, and the inverter device 2 receives the DC voltage of the battery 3 and sends the frequency- and phase-controlled voltage to the induction motor 1. Further, during the regenerative operation, the regenerative current is sent from the inverter device 2 to the battery 3 through the semiconductor switch S ₃ and the diode D ₂ , and the battery 3 can be supplied with regenerative power.

(2) Next, the operation at the time of switching the rotational speed increasing heavy load will be described. When the engine speed is increased and the load is switched, the accelerator opening signal c exceeds the set value because the load is heavy (therefore, the DC voltage signal e is large and the inverter output voltage is close to the inverter output voltage upper limit value). , The motor rotational speed is operating in a region smaller than n ₂ , and the rotational speed increases and the rotational speed exceeds n ₁₁ .

When the number of revolutions increases and the number of revolutions exceeds n ₁₁ at the time of switching the heavy load, the system controller 7a
Turns off the semiconductor switches S ₂ and S ₃ ,
Switching operation of semiconductor switch S ₁ (ON, OFF
Repeat). Therefore, the boost chopper circuit 10
Then, not only the voltage of the battery 3 but also the voltage of the boost chopper circuit 10 is applied to the inverter device 2. Therefore, when the motor speed becomes n ₂ and the 4-pole operation is switched to the 2-pole operation, the inverter output voltage exceeds the inverter output voltage upper limit value (the value that maximizes the inverter output voltage when only the battery voltage is used). Can grow. That is, the four-pole operation voltage and the two-pole operation voltage can be increased so that the torque does not become insufficient. Therefore, when switching from 4 poles to 2 poles, the number of poles can be switched without torque fluctuation.

The switching operation of the semiconductor switch S ₁ is ON / OFF controlled according to the voltage value required by the boost chopper circuit 10. The value of the rotation speed n ₁₁ is appropriately determined according to the time required for the boosting operation of the boost chopper circuit 10.

In this way, when switching from 4 poles to 2 poles under heavy load, the voltage by the boost chopper circuit 10 is also added and input. However, when the motor output is 60 kW class, the energy to be added is 75. Since it may be about [KJ], the capacity of the boost chopper circuit 10 may be small,
In addition, a small circuit can be obtained.

(3) Next, the operation at the time of switching the rotation speed decreasing heavy load will be described. When the rotation speed is reduced and the heavy load is switched, the accelerator opening signal c exceeds the set value because the load is heavy (therefore, the DC voltage signal e is large and the inverter output voltage is close to the inverter output voltage upper limit value). The motor rotational speed is operating in a region larger than n ₁ , and the rotational speed has decreased and the rotational speed has decreased below n ₂₂ .

When the rotation speed is reduced and the heavy load is switched, and the rotation speed decreases and becomes smaller than n ₂₂ , the system control device 7a turns off the semiconductor switches S ₂ and S ₃ and at the same time, the semiconductor switch S ₁ The switching operation (repeating ON and OFF) is performed. Therefore, the step-up chopper circuit 10 is activated, and the inverter device 2 is not only supplied with the voltage from the battery 3 but also the step-up chopper circuit 1
A voltage of 0 is also applied. Therefore, the motor speed is n ₁
Therefore, when the two-pole operation is switched to the four-pole operation, the inverter output voltage can exceed the inverter output voltage upper limit value (the value at which the inverter output voltage becomes maximum when only the battery voltage is used) and increase. That is, the two-pole operation voltage and the four-pole operation voltage can be increased so that the torque does not become insufficient. Therefore, when switching from 2 poles to 4 poles, the number of poles can be switched without torque fluctuation.

The switching operation of the semiconductor switch S ₁ is ON / OFF controlled according to the voltage value required by the boost chopper circuit 10. The value of the rotation speed n ₂₂ is appropriately determined according to the time required for the boosting operation of the boost chopper circuit 10.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the inverter device 20, the flywheel drive motor 21 that is an AC motor, and the flywheel 22 that is directly connected to the motor 21.
And a rotation speed sensor 23 directly connected to the flywheel 22.
And a current detector 24.

The inverter device 20 performs a power running operation and a regenerative operation with respect to the motor 21. That is, during the power running operation, the inverter device 20 receives the voltage of the battery 3 and the regenerative voltage of the inverter device 2, and outputs the phase-controlled voltage to the motor 2
1 to drive the motor 21 to rotate. At this time, the flywheel 22 is rotated by the motor 21, and energy is accumulated as a rotary motion. Further, during the regenerative operation, the inverter device 20 functions as a converter, receives regenerative power from the motor 21 that functions as a generator by being rotated by the rotational energy of the flywheel 22, and returns this regenerated power to the battery 3 and the inverter device 2. Then, the inverter device 20 responds to the inverter drive signal f for the flywheel motor sent from the system control device 7b.
Performs power running or regenerative motion.

The rotation speed sensor 23 sends a flywheel rotation speed signal g indicating the rotation speed of the flywheel 22 to the system controller 7b. The current detector 24 detects the current flowing between the inverter device 20 and the motor 21 and outputs the flywheel drive motor current signal h to the system controller 7.
Send to b. The voltage detector 12 sends the DC voltage signal e to the system controller 7b. The configuration and operation of other parts are
This is similar to the conventional technique shown in FIG.

Here, the operation of the characteristic part of the second embodiment will be described with reference to FIGS. 3 and 2, (11) during normal operation (12) at increasing rotational speed and at heavy load switching (13) rotating. A description will be separately given when switching the number of heavy loads. The states (11), (12), and (13) are the same as the states (1), (2), and (3) described above.

(11) First, the operation during normal operation will be described. During energization operation, the system control device 7b
The inverter drive signal f from the inverter device 2
0 is made to perform a power running operation, the flywheel 22 is rotated by the drive motor 22, and energy is accumulated as a rotary motion.

(12) Next, the operation at the time of switching the rotational speed increasing heavy load will be described. When the rotation speed increases and the load is switched, if the rotation speed increases and exceeds n ₁₁ , the system controller 7
By the inverter drive signal f from b, the inverter device 20 is regeneratively operated (functions as a converter), and the regenerative electric power of the motor 21 rotated by the rotational energy of the flywheel 22 is sent to the inverter device 2. Therefore, not only the voltage from the battery 3 but also the regenerative voltage from the inverter device 20 is applied to the inverter device 2. Therefore, when the motor speed becomes n ₂ and the 4-pole operation is switched to the 2-pole operation, the inverter output voltage exceeds the inverter output voltage upper limit value (the value that maximizes the inverter output voltage when only the battery voltage is used). Can grow. That is, the four-pole operation voltage and the two-pole operation voltage can be increased so that the torque does not become insufficient. Therefore, when switching from 4 poles to 2 poles, the number of poles can be switched without torque fluctuation.

The value of the rotation speed n _{11 is} the value of the inverter device 2
0, the motor 21, and the flywheel 22 are appropriately determined according to the time required to change the operation mode of the energy storage device.

(13) Next, the operation at the time of switching the rotation speed decreasing heavy load will be described. When the rotation speed is reduced and the heavy load is switched, if the rotation speed decreases and becomes smaller than n ₂₂ , the inverter drive signal f from the system control device 7b causes the inverter device 20 to regenerate (function as a converter) flywheel. The regenerative electric power of the motor 21 rotated by the rotational energy of 22 is sent to the inverter device 2. Therefore, not only the voltage from the battery 3 but also the regenerative voltage from the inverter device 20 is applied to the inverter device 2. Therefore, when the motor speed becomes n ₁ and the 2-pole operation is switched to the 4-pole operation, the inverter output voltage exceeds the inverter output voltage upper limit value (the value that maximizes the inverter output voltage when only the battery voltage is used). Can grow. That is, the two-pole operation voltage and the four-pole operation voltage can be increased so that the torque does not become insufficient. Therefore, when switching from 2 poles to 4 poles,
The number of poles can be switched without torque fluctuation.

The value of the rotation speed n _{22 is} the value of the inverter device 2
0, the motor 21, and the flywheel 22 are appropriately determined according to the time required to change the operation mode of the energy storage device.

In the embodiment shown in FIG. 3, the energy storage device is constructed by using the flywheel, but the energy storage device may be constructed by using a superconducting coil, an electric double tank capacitor or the like.

Further, the number of poles can be switched not only between 2 poles and 4 poles but also between N poles and 2 N poles (N is an even number) in general.

Further, the inverter is not limited to the voltage type inverter, but a current type inverter may be used.

[0060]

As described above, when the number of poles of the induction motor is changed under heavy load, the voltage from the step-up chopper circuit or the energy storage device is added to the DC voltage from the DC voltage source so that the inverter device can be operated. Since the voltage is applied, the inverter output voltage can be increased and the number of poles can be switched without torque fluctuation. Therefore, when applied to an electric vehicle, the driver can drive comfortably without feeling a torque shot.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a pole number switching operation state.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between rotation speed and torque.

FIG. 5 is a characteristic diagram showing the relationship between the rotation speed and the torque when the number of poles is switched.

FIG. 6 is a configuration diagram showing a structure of a 6-phase winding.

FIG. 7 is a configuration diagram showing a conventional technique.

FIG. 8 is a characteristic diagram showing a relationship between rotation speed and torque under heavy load.

[Explanation of symbols]

1 Induction Motor 2 Inverter Device 3 Battery 4 DC Capacitor 5 Rotation Speed Sensor 6 Current Detector 7, 7a, 7b System Controller 10 Boost Chopper Circuit 11 Regenerative Current Bypass Circuit 12 Voltage Detector 20 Inverter Device 21 Flywheel Drive Motor 22 Fly Wheel 23 Rotation speed sensor 24 Current detector L ₁ Reactor S ₁ , S ₂ , S ₃ Semiconductor switch D ₁ , D ₂ Diode a Motor rotation speed signal b Motor current signal c Accelerator opening signal d Inverter drive signal e DC voltage signal f Flywheel motor inverter drive signal g Flywheel rotation speed signal h Flywheel drive motor current signal

Claims (2)

[Claims] 1. An induction motor having a stator winding structure equivalent to having three N-phase windings (N is an even number), and a speed of the induction motor by changing a voltage frequency applied to the induction motor. An inverter device for controlling the phase and frequency of the voltage of each phase winding to drive the induction motor with a pole number of 2N in the low speed operation region and with the pole number of the induction motor in a high speed operation region with N A direct current voltage source for supplying a direct current voltage to the inverter device, a semiconductor switch and a diode, which are connected between the inverter device and the direct current power source, and are connected from the direct current voltage source to the inverter device. It consists of a regenerative current bypass circuit that has the function of supplying voltage and the function of regenerating voltage from the inverter device to the DC voltage source, and the reactor and semiconductor switch. A boost chopper circuit connected between the inverter device and the DC power supply and having a function of supplying a boost voltage to the inverter device, and exhibiting the functions of the regenerative current bypass circuit and the boost chopper circuit. And a control device for controlling to stop the induction motor.When the operating region of the induction motor changes from a low speed operating region to a high speed operating region when the load is heavy, and when the induction motor operates when the load is heavy. When the operating region changes from the high-speed operating region to the low-speed operating region, control is performed so that the boosted voltage supply function by the boost chopper circuit is exerted, and voltage regeneration is performed while the voltage supply function by the regenerative current bypass circuit is exerted. It is controlled so that the function is stopped.In addition, during light load operation, and when the induction motor switches the number of poles, When operating in the number-of-revolutions region, it is controlled to stop the boost voltage supply function by the boost chopper circuit, and to control the voltage supply function and the voltage regeneration function by the regenerative current bypass circuit. A characteristic operation control device for pole number switching motors. 2. An induction motor having a stator winding structure equivalent to having three N-phase windings (N is an even number), and a speed of the induction motor by changing a voltage frequency applied to the induction motor. An inverter device for controlling the phase and frequency of the voltage of each phase winding to drive the induction motor with a pole number of 2N in the low speed operation region and with the pole number of the induction motor in a high speed operation region with N A direct current voltage source for supplying a direct current voltage to the inverter device; a flywheel; an alternating current motor connected to the flywheel; and a direct current voltage generated by the direct current voltage source and a regenerative voltage generated by the inverter device. An AC motor having a function of performing a power running operation of the motor and a function of a regenerative operation of converting the regenerative voltage of the AC motor into DC and supplying the DC voltage to the inverter device. It has an energy storage device consisting of a power inverter device and a control device that controls the inverter device for the AC motor of the energy storage device to perform a power running operation or a regenerative operation. When the operating range of the electric motor changes from the low-speed operating range to the high-speed operating range, and when the operating range of the induction motor changes from the high-speed operating range to the low-speed operating range when the load is heavy, the AC motor inverter device is used. Is controlled so as to perform regenerative operation, and when the induction motor is operated in a rotation speed region other than the rotation speed region for switching the number of poles, the inverter device for the AC motor is operated. An operation control device for a pole number switching electric motor, which is controlled to perform a power running operation.