JP2018057161A - Control apparatus of induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus of an induction motor, capable of improving responsibility of the induction motor or a power efficiency by a simple control as compared with a vector control system from low rotational speed regions to high rotational speed region.SOLUTION: Electric power supplies 20a and 20b that are a control apparatus 50 of an induction motor 10, include a DCDC converter circuit 21 that converts an electric power supplied from a battery 30, and outputs a predetermined output current; and an inverter circuit 22 that converts a DC power to an AC power. On the basis of a detection value of an output current of the DCDC converter circuit 21, a magnetization current is acquired. By using a map for corresponding the magnetization current and a target slip frequency as a target value of the magnetization current and a slip frequency. the target slip frequency is set. On the basis of a rotational speed of the induction motor 10 and the target slip frequency set by a setting part, a driving frequency of the inverter circuit 22 is set, and the inverter circuit 22 is driven by the set driving frequency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an induction motor.

  In order to suppress the overcurrent from flowing to the motor, a configuration that combines a step-down chopper circuit (DCDC converter circuit) that performs constant current control and a voltage source inverter circuit is known for a power supply device that supplies power to the motor. (For example, Patent Document 1).

Japanese Patent No. 3278188

  In a configuration in which a voltage source inverter circuit is applied to an induction motor, a vector control method is known as a control method for improving the response and power efficiency of the induction motor. Here, the vector control method requires coordinate transformation. For this reason, the control is complicated, and it is necessary to detect the rotation angle of the rotor. In particular, in a region where the rotational speed is extremely high, the control device (microcomputer) is required to perform computation at a speed corresponding to the rotational speed. For this reason, a high-performance control device is required, and the cost increases.

  The present invention has been made in view of the above problems, and can improve the responsiveness and power efficiency of an induction motor from a low rotation speed region to a very high speed region with simple control compared to a vector control method. The main object is to provide a control device for a possible induction motor.

  This configuration is a control device (50) for the induction motor (10), and the power supply device (100) for supplying power to the induction motor converts the power supplied from the DC power source (30), A DCDC converter circuit (21) for outputting an output current; and a voltage source inverter circuit (22) for converting DC power output from the DCDC converter circuit into AC power, the output of the DCDC converter circuit Based on the detected current value, the magnetizing current flowing through the induction motor is obtained, and the magnetizing current and a map that associates the magnetizing current with a target slip frequency that is a target value of the slip frequency of the induction motor are used. And a setting unit (59) for setting the target slip frequency, the rotational speed of the rotor (12) of the induction motor, and before setting by the setting unit And the target slip frequency, on the basis of, sets the commutation frequency of the voltage-type inverter circuit to drive the voltage source inverter circuit in its set the commutation frequency.

  According to this configuration, it is possible to perform maximum torque control and maximum efficiency control without performing vector control. In this configuration, the magnetizing current flowing through the induction motor is acquired based on the detected value of the output current of the DCDC converter circuit, and the slip frequency of the induction motor is set as the target based on the magnetizing current and the rotational speed of the rotor. It can be a slip frequency. Here, if the target slip frequency is suitably set, the response and power efficiency of the induction motor can be improved. That is, the responsiveness and power efficiency of the induction motor can be improved over a region where the rotational speed is low to a region where the rotational speed is extremely high with simple control compared to the vector control method.

The electrical block diagram containing the induction motor of 1st Embodiment. The functional block diagram showing the control apparatus of 1st Embodiment. The figure showing the relationship between a magnetizing current, a slip frequency, and the maximum output torque. The figure showing an example of the map which matches the magnetizing current at the time of a maximum torque output, and a slip frequency. The figure showing the response characteristic of the induction motor of 1st Embodiment. The figure showing the time change of the phase current of the induction motor of 1st Embodiment. The figure showing the relationship between magnetizing current, a slip frequency, and the power efficiency in an induction motor. The functional block diagram showing the control apparatus of 4th Embodiment.

(First embodiment)
FIG. 1 shows an electrical configuration diagram of the induction motor 10 of the present embodiment. The induction motor 10 according to the present embodiment is a multiphase induction motor, and more specifically, a six-phase induction motor having a six-phase armature winding. The induction motor 10 includes a stator 11 and a rotor 12. The induction motor 10 is, for example, an in-vehicle induction motor mounted on a vehicle.

  The stator 11 includes armature winding groups 13a and 13b. The armature winding group 13a is supplied with power from the power supply circuit 20a, and the armature winding group 13b is supplied with power from the power supply circuit 20b. The armature winding group 13a is composed of U, V, and W phase armature windings, and the armature winding group 13b is composed of X, Y, and Z phase armature windings. The U, V, and W phase armature windings form an angle of 120 degrees, and the X, Y, and Z phase armature windings form an angle of 120 degrees. The U-phase electric winding and the X-phase armature winding form 30 degrees.

  The rotor 12 includes an electric conductor. The rotor 12 may be a wound rotor or a cage rotor.

  The power supply circuits 20 a and 20 b include a DCDC converter circuit 21 and an inverter circuit 22. The power supply circuits 20a and 20b convert DC power supplied from the battery 30 into AC power and supply the AC power to the armature winding groups 13a and 13b. A smoothing capacitor C1 is provided between the battery 30 and the power supply circuits 20a and 20b. The battery 30 as the “DC power supply” may be a DCDC converter circuit or the like.

  The control device 50 controls the induction motor 10 by adjusting the outputs of the power supply circuits 20a and 20b. The power supply circuits 20a and 20b and the control device 50 constitute one power supply device 100.

  The DCDC converter circuit 21 is a synchronous rectification step-down chopper circuit. The DCDC converter circuit 21 includes switches SW1 and SW2, a reactor L, a smoothing capacitor C2, and a regenerative diode DF. Each of the switches SW1 and SW2 is a semiconductor switching element, specifically, an N-channel MOS-FET. Each of the switches SW1 and SW2 includes a body diode. The switches SW1 and SW2 may be IGBTs.

  The drain of the switch SW1 is connected to the positive electrode of the battery 30 (the high voltage side terminal of the smoothing capacitor C1), and the source of the switch SW1 is connected to the first terminal of the reactor L. The second terminal of the reactor L is connected to the high voltage side terminal of the smoothing capacitor C2 (the one on the high voltage side among the output terminals of the DCDC converter circuit 21) and the one on the high voltage side among the input terminals of the inverter circuit 22. ing. The drain of the switch SW2 is connected to the source of the switch SW1 and the first terminal of the reactor L, and the source of the switch SW2 is connected to the negative electrode of the battery 30 (the low voltage side terminal of the smoothing capacitor C1).

  The low voltage side terminal of the smoothing capacitor C2 (the low voltage side terminal among the output terminals of the DCDC converter circuit 21) is the negative electrode of the battery 30 (the low voltage side terminal of the smoothing capacitor C1) and the input terminal of the inverter circuit 22 Connected to the low voltage side. When the switches SW1 and SW2 are alternately turned on and off, the output voltage of the battery 30 is stepped down and output to the inverter circuit 22.

  The regenerative diode DF has an anode connected to the second terminal of the reactor L2 (the output terminal of the DCDC converter circuit 21 on the higher voltage side), and the drain of the switch SW1 (the higher input terminal of the DCDC converter circuit 21). The cathode is connected to the voltage side. The regenerative diode DF causes the battery 30 to regenerate a current flowing from the inverter circuit 22 side (armature winding group 13a, 13b side) to the DCDC converter circuit 21.

  The inverter circuit 22 is a voltage source inverter circuit that converts an input voltage into an alternating current as it is and outputs it. The inverter circuit 22 includes upper arm switches SWp1 to SWp3 and lower arm switches SWn1 to SWn3. Each of the switches SWp1 to SWp3 and SWn1 to SWn3 is a semiconductor switching element, specifically, an N channel MOS-FET. The switches SWp1 to SWp3 and SWn1 to SWn3 include body diodes Dp1 to Dp3 and Dn1 to Dn3, respectively. The switches SWp1 to SWp3 and SWn1 to SWn3 may be IGBTs, respectively.

  The upper arm switch SWp1, the lower arm switch SWn1, the upper arm switch SWp2, the lower arm switch SWn2, and the upper arm switch SWp3 and the lower arm switch SWn3 are respectively connected in series. More specifically, the drains of the upper arm switches SWp1 to SWp3 are respectively connected to the output terminals of the DCDC converter circuit 21 on the high voltage side. The sources of the upper arm switches SWp1 to SWp3 are connected to the drains of the lower arm switches SWn1 to SWn3, respectively. The sources of the lower arm switches SWn1 to SWn3 are connected to the output terminals of the DCDC converter circuit 21 on the low voltage side, respectively.

  The connection point between the upper arm switch SWp1 and the lower arm switch SWn1 of the power circuit 20a is connected to the U-phase armature winding, and the connection point between the upper arm switch SWp2 and the lower arm switch SWn2 of the power circuit 20a is The connection point between the upper arm switch SWp3 and the lower arm switch SWn3 of the power supply circuit 20a is connected to the W-phase armature winding.

  The connection point between the upper arm switch SWp1 and the lower arm switch SWn1 of the power circuit 20b is connected to the X-phase armature winding, and the connection point between the upper arm switch SWp2 and the lower arm switch SWn2 of the power circuit 20b is Are connected to the Y-phase armature winding, and the connection point between the upper arm switch SWp3 and the lower arm switch SWn3 of the power supply circuit 20b is connected to the Z-phase armature winding.

  A three-phase alternating current is supplied to the armature winding group 13a by the inverter circuit 22 of the power supply circuit 20a, and a three-phase alternating current is supplied to the armature winding group 13b by the inverter circuit 22 of the power supply circuit 20b.

  The control device 50 acquires the detected value of the output current Iout of the DCDC converter circuit 21 of the power supply circuits 20a and 20b from the current sensor 51 of the power supply circuits 20a and 20b, respectively. In addition, the control device 50 acquires a detected value of the rotation angle of the rotor 12 from the rotation angle sensor 52. In addition, the control device 50 acquires a detected value of the temperature of the induction motor 10 from the temperature sensor 53. In addition, the control device 50 acquires the target rotational speed of the induction motor 10 from the host control device 40 (ECU: Electronic Control Unit).

  The control device 50 issues a command to the gate drive circuits 23 and 24 based on the acquired detection value and the target rotation speed, and drives the switch SW constituting the DCDC converter circuit 21 and the inverter circuit 22 of the power supply circuits 20a and 20b. The induction motor 10 is controlled. The control device 50 is a known microcomputer composed of a CPU, a ROM, a RAM, and the like.

  Control of the induction motor 10 by the control device 50 will be described using a functional block diagram of the control device 50 shown in FIG. Since the functional block related to the control of the power supply circuit 20a and the functional block related to the control of the power supply circuit 20a are equivalent, only the functional block related to the control of the power supply circuit 20a is shown in FIG. The functional block regarding is omitted.

  The speed calculation unit 62 calculates the rotation speed (actual value) of the rotor 12 based on the detected value of the rotation angle of the rotor 12 acquired from the rotation angle sensor 52. The deviation calculation unit 54 calculates a deviation between the target rotation speed acquired from the host controller 40 and the actual value of the rotation speed. The PI calculation unit 55 calculates a target current Iref that is a target value of the output current Iout of the DCDC converter circuit 21 by performing a proportional / integral calculation (PI calculation) on the deviation calculated by the deviation calculation unit 54. To do. The current limiting unit 56 limits the target current Iref, which is the calculation result of the PI calculation unit 55, within a predetermined range. Thereby, it is possible to prevent an excessive current from being output from the DCDC converter circuit 21.

  The deviation calculation unit 57 calculates a deviation between the target current Iref and the detected value of the output current Iout of the DCDC converter circuit 21 by the current sensor 51. The PI calculation unit 58 sets the duty of the DCDC converter circuit 21 by performing a proportional / integral calculation (PI calculation) on the deviation calculated by the deviation calculation unit 57. Then, the gate drive circuit 23 drives the switch SW of the DCDC converter circuit 21 according to the set duty. That is, the control device 50 performs constant current control so that the output current Iout of the DCDC converter circuit 21 becomes the target current Iref.

  Here, the control device 50 of the present embodiment maps the magnetizing current I flowing through the induction motor 10 (armature winding group 13a) and the target slip frequency, which is the target value of the slip frequency of the induction motor 10, to a map. Based on this, a slip frequency setting unit 59 for setting a target slip frequency is provided.

  FIG. 3 shows the slip frequency, the output torque T of the induction motor 10, and the magnetizing current I that flows through the induction motor 10 (the current that contributes to the magnetic flux formed by the armature winding group 13a. The figure showing the relationship with the current which isolate | separated the iron loss current from the flowing excitation current is shown. The magnitude of the exciting current flowing through the armature winding group 13a is equal to the magnitude of the output current Iout of the DCDC converter circuit 21. When the magnetizing current I of the induction motor 10 is fixed, the output torque T of the induction motor 10 becomes maximum at a predetermined slip frequency.

  Therefore, a map that associates the magnetizing current I flowing through the induction motor 10 shown in FIG. 4 with the slip frequency at which the output torque T of the induction motor 10 is maximum is created in advance. And the said map is memorize | stored in ROM of the control apparatus 50 (slip frequency setting part 59). The map can be created based on simulations or experiments.

  The slip frequency setting unit 59 (FIG. 2) sets a target slip frequency based on the map and the magnetizing current I flowing through the induction motor 10. Thereby, the output torque T of the induction motor 10 can be maximized with respect to the magnetizing current I (the output current Iout of the DCDC converter circuit 21).

  Further, the relationship among the slip frequency, the output torque T of the induction motor 10, and the magnetizing current I changes according to the temperature of the induction motor 10. Therefore, the slip frequency setting unit 59 acquires the detected value of the temperature of the induction motor 10 from the temperature sensor 53, and switches the map based on the detected value.

  Further, the control device 50 of the present embodiment includes a current separation unit 63 that acquires a current obtained by separating the iron loss current in the induction motor 10 from the output current Iout of the DCDC converter circuit 21 as the magnetization current I. The current separation unit 63 calculates the iron loss current in the induction motor 10 based on the output current Iout of the DCDC converter circuit 21 and the rotation speed of the induction motor 10. Then, the current separator 63 calculates the magnetizing current I by subtracting the iron loss current from the output current Iout (excitation current) of the DCDC converter circuit 21. The slip frequency setting unit 59 acquires the calculated value of the magnetizing current I from the current separating unit 63 and sets the target slip frequency based on the calculated value of the magnetizing current I.

  Here, since the iron loss current in the induction motor 10 is relatively small in the region where the rotation speed of the induction motor 10 is low, the excitation current flowing through the armature winding group 13a can be regarded as the magnetizing current I of the induction motor 10. it can. That is, when the rotational speed of the induction motor 10 is low, the current separation unit 63 may be omitted, and the output current Iout of the DCDC converter circuit 21 may be regarded as the magnetization current I flowing through the induction motor 10 and acquired.

  Returning to the description of FIG. 2, the adder 60 generates the armature winding group 13 a by adding the rotation speed converted value of the target slip frequency to the rotation speed of the rotor 12 acquired from the speed calculator 62. The rotation speed of the magnetic field (synchronous speed of the induction motor 10) is set.

  The commutation frequency calculation unit 61 converts the synchronous speed of the induction motor 10 into a commutation frequency (the synchronous speed of the induction motor 10 × the number of poles of the induction motor 10). The gate drive circuit 24 drives the switches SWp1 to SWp3 and SWn1 to SWn3 of the inverter circuit 22 according to the commutation frequency. That is, the control device 50 causes the frequency (rotational speed) of the three-phase alternating current output from the inverter circuit 22 to be the sum of the current rotational speed of the induction motor 10 and the rotational speed converted value of the target slip frequency. The inverter circuit 22 is controlled.

  The effects of this embodiment will be described below.

  According to the configuration of this embodiment that adjusts the slip frequency, maximum torque control and maximum efficiency control can be performed without performing vector control. In the configuration of the present embodiment, the slip frequency of the induction motor 10 can be set as the target slip frequency based on the rotation speed of the rotor 12 and the magnetizing current I flowing through the armature winding group 13a. Here, if the target slip frequency is suitably set, the responsiveness and power efficiency of the induction motor 10 can be improved. That is, the response and power efficiency of the induction motor 10 can be improved with simple control compared to the vector control method.

  The current separation unit 63 calculates a current obtained by separating the iron loss current in the induction motor 10 from the detected value of the output current Iout (excitation current flowing through the armature windings 13a and 13b) of the DCDC converter circuit 21 as the magnetizing current I. Particularly in a region where the rotation speed is high, the iron loss, which is a loss in the induction motor 10, increases, and the proportion of the iron loss current in the excitation current increases. Therefore, the current separation unit 63 calculates the iron loss current based on the output current Iout of the DCDC converter circuit 21 and the rotation speed of the induction motor 10, and separates the iron loss current from the output current Iout of the DCDC converter circuit 21. Thus, the magnetizing current I is calculated. With this configuration, in the region where the rotational speed of the induction motor 10 is high, the setting accuracy of the target slip frequency by the slip frequency setting unit 59 can be improved, and the responsiveness and power efficiency of the induction motor 10 can be further improved. .

  According to the configuration of the present embodiment that adjusts the output current Iout of the DCDC converter circuit 21 based on the difference between the detected value of the rotational speed and the target rotational speed that is the target value of the rotational speed, the rotational speed of the induction motor 10 is adjusted. Can be made closer to the target rotational speed. Further, by controlling the output current Iout, the output current Iout of the DCDC converter circuit 21, that is, even when the voltage of the battery 30 that is a power source for supplying power to the DCDC converter circuit 21 fluctuates, that is, The current supplied to the induction motor 10 is substantially constant. For this reason, it can suppress that an overcurrent flows into the induction motor 10. Even if the voltage of the battery 30 fluctuates, fluctuations in the rotation speed of the induction motor 10 can be suppressed.

  FIG. 6 shows the waveform of the current flowing through each armature winding when the control of this embodiment is performed, and the waveform of the current flowing through each armature winding when PWM control (conventional control) is performed in the inverter circuit. Indicates. When the PWM control is performed in the low impedance induction motor 10, an overshoot of the current flowing in the armature winding is remarkably generated. By performing the control of the present embodiment, it is possible to suppress overshoot of the current flowing through the armature winding and suppress the overcurrent from flowing through the armature winding.

  In particular, the reactor L of the DCDC converter circuit 21 of the present embodiment is connected in series with the armature winding. For this reason, even when the inductance component of the armature winding is small, the inductance component of the reactor L of the DCDC converter circuit 21 causes an overshoot in the output current Iout output from the DCDC converter circuit 21 to the armature winding. Shooting can be suppressed.

  According to the configuration of this embodiment in which the target slip frequency is set using a map that associates the magnetizing current I with the target slip frequency so that the output torque T of the induction motor 10 becomes maximum, the magnetizing current I (output current) Iout) can be controlled so that the output torque T of the induction motor 10 is maximized. FIG. 5 shows a temporal change in the rotational speed of the induction motor 10 when the control of the present embodiment is performed, and a temporal change in the rotational speed of the induction motor 10 when the PWM control is performed in the inverter circuit. The responsiveness of the rotational speed can be improved by maximizing the output torque T by the control of the present embodiment.

  The slip frequency setting unit 59 of the present embodiment switches the map based on the temperature of the induction motor 10. The output torque characteristic and the power efficiency characteristic with respect to the excitation current of the induction motor 10 (the output current of the power supply device 100) and the power efficiency characteristic vary depending on the temperature of the induction motor 10 (the temperature of the armature winding of the induction motor 10 and the temperature of the conductor). . Therefore, based on the temperature of the induction motor 10, the map for associating the magnetizing current I of the DCDC converter circuit 21 (power supply device 100) with the slip frequency is switched. Thereby, the rotational speed of the induction motor 10 can be made closer to the target rotational speed with better responsiveness.

  The induction motor 10 of this embodiment has 3n-phase (n is a natural number of 2 or more) armature windings as armature windings. By making the induction motor 10 have a multi-phase armature winding, the magnetic flux formed by the armature winding can be brought close to a sine wave, thereby improving the power efficiency and output response of the induction motor 10. Can be made.

(Second Embodiment)
The slip frequency setting unit 59 (FIG. 2) in the first embodiment uses a map that associates the magnetizing current I with the slip frequency at which the output torque T of the induction motor 10 is maximized, and uses the target slip frequency of the induction motor 10. It was set as the structure which sets. By changing this, the slip frequency setting unit 59 in the second embodiment sets the target slip frequency using a map that associates the magnetizing current I with the slip frequency at which the power efficiency of the induction motor 10 is maximized. To do. According to this configuration, it is possible to control the output current Iout of the DCDC converter circuit 21 so that the power efficiency of the induction motor 10 is improved.

  FIG. 7 is a diagram illustrating the relationship among the slip frequency, the output torque T of the induction motor 10, and the magnetizing current I (current flowing through the armature winding group 13a). When the magnetizing current I is set to a predetermined value, the power efficiency of the induction motor 10 is maximized at a predetermined slip frequency. Here, when the magnetizing current I is set to a predetermined value, the slip frequency at which the power efficiency of the induction motor 10 is highest is generally a value of about 5% of the synchronous frequency of the induction motor 10. Further, the slip frequency at which the power efficiency of the induction motor 10 becomes maximum when the magnetizing current I is set to a predetermined value can be obtained by simulation or experiment.

(Third embodiment)
The slip frequency setting unit 59 in the third embodiment sets a target slip frequency using a different map based on the rotational speed of the rotor 12. Specifically, when the target rotational speed changes in the increasing direction, the slip frequency setting unit 59 induces the magnetizing current I and the target slip frequency until the rotational speed of the rotor 12 reaches the target rotational speed. The target slip frequency is set using a map that is associated so that the output torque T of the electric motor 10 is maximized. Here, the case where the target rotation speed changes in the increasing direction is, for example, the time when the induction motor 10 starts to be driven.

  Further, the slip frequency setting unit 59 maps the magnetizing current I and the target slip frequency so that the power efficiency of the induction motor 10 is maximized after the rotation speed of the rotor 12 reaches the target rotation speed. Use to set the target slip frequency.

  According to the configuration of the present embodiment, until the rotational speed of the induction motor 10 reaches the target rotational speed, the rotational speed of the induction motor 10 is controlled by controlling so that the output torque T of the induction motor 10 is maximized. The rotation speed can be approached with good responsiveness. Furthermore, after the rotational speed of the induction motor 10 reaches the target rotational speed, the power efficiency can be improved by controlling the induction motor 10 so that the power efficiency becomes the highest. That is, the power efficiency can be improved while improving the responsiveness of the induction motor 10.

(Fourth embodiment)
The control device 50 according to the first embodiment outputs the output current Iout of the DCDC converter circuit 21 based on the difference between the detected value of the rotational speed of the induction motor 10 and the target rotational speed that is the target value of the rotational speed of the induction motor 10. Adjust. In this embodiment, the torque sensor 64 that detects the output torque T of the induction motor 10 is provided. Furthermore, the control device 50 according to the present embodiment is configured such that the target torque that is the target value of the output torque T of the induction motor 10 input from the host control device 40 and the detected value of the output torque T of the induction motor 10 by the torque sensor 64. Based on the above, the output current Iout of the DCDC converter circuit 21 is adjusted. The host control device 40 acquires the detected value of the output torque T of the induction motor 10 by the torque sensor 64.

  More specifically, as shown in FIG. 8, the deviation calculating unit 65 calculates the deviation between the detected value of the output torque T of the induction motor 10 by the torque sensor 64 and the target torque. Then, the PI control is performed based on the deviation between the target value of the output torque T calculated by the deviation calculating unit 65 and the detected value. The target current Iref may be calculated based on the target torque, and the PI control based on the deviation between the target current Iref and the output current Iout may be performed. In the configuration shown in FIG. 8, the current separation unit 63 is omitted as compared with the configuration shown in FIG. It is good also as a structure which changes this and is equipped with the electric current separation part 63. FIG.

  According to the configuration of the present embodiment, the output torque T of the induction motor 10 can be brought close to an arbitrary target value. That is, constant torque control can be performed.

(Other embodiments)
In place of the PI control for the rotation speed and the PI control for the output current Iout in the first embodiment, P control (proportional control) or PID control (proportional / integral / derivative control) may be performed.

  In the above embodiment, the DCDC converter circuit 21 is a step-down chopper circuit, but this may be changed. For example, it may be a booster circuit or a step-up / down circuit. Moreover, an insulation type DCDC converter circuit may be used.

  -In 1st Embodiment, although it was set as the structure which has 2 sets x 3 phase armature winding as an armature winding, it is good also as a structure which changes this and has 3 phase armature winding. Moreover, a single phase induction motor may be sufficient.

  The control device 50 (current separation unit 63) of the first embodiment may be configured to acquire the magnetizing current I based on the average value of the detection values of the current sensors 51 provided in the power supply circuits 20a and 20b. Good. Moreover, it is good also as a structure which provides the current sensor 51 only in one of the power supply circuits 20a and 20b, and implements control of both the power supply circuits 20a and 20b based on the detected value of the current sensor 51.

  DESCRIPTION OF SYMBOLS 10 ... Induction motor, stator ... 12, 21 ... DCDC converter circuit, 22 ... Inverter circuit, 30 ... Battery, 50 ... Control apparatus, 59 ... Slip frequency setting part, 100 ... Power supply device.

Claims (9)

A control device (50) for the induction motor (10),
The power supply device (100) for supplying power to the induction motor converts the power supplied from the DC power supply (30) and outputs a predetermined output current, and outputs from the DCDC converter circuit. A voltage source inverter circuit (22) for converting the DC power to be converted into AC power,
Based on the detected value of the output current of the DCDC converter circuit, the magnetizing current flowing through the induction motor is acquired, the magnetizing current, and the target slip frequency that is the target value of the magnetizing current and the slip frequency of the induction motor, A setting unit (59) for setting the target slip frequency using a map that associates
Based on the rotational speed of the rotor (12) of the induction motor and the target slip frequency set by the setting unit, a commutation frequency of the voltage source inverter circuit is set, and the set commutation frequency is set. A control device for driving the voltage source inverter circuit at a flow frequency. A current separation unit (63) for calculating, as the magnetization current, a current obtained by separating the iron loss current in the induction motor from the detected value of the output current of the DCDC converter circuit;
The control device according to claim 1, wherein the setting unit sets the target slip frequency using a calculated value of the magnetizing current by the current separation unit.   3. The output current of the DCDC converter circuit is adjusted based on a difference between a detected value of the rotational speed of the induction motor and a target rotational speed that is a target value of the rotational speed of the induction motor. Control device.   3. The output current of the DCDC converter circuit is adjusted based on a difference between a detected value of the output torque of the induction motor and a target torque that is a target value of the output torque of the induction motor. Control device.   The said setting part sets the said target slip frequency using the map which matches the said magnetizing current and the said target slip frequency so that the output torque of the said induction motor may become the maximum. The control device according to item.   The said setting part sets the said target slip frequency using the map which matches the said magnetizing current and the said target slip frequency so that the power efficiency of the said induction motor may become the highest. The control device according to item. The setting unit
When the target rotational speed changes in the increasing direction, the magnetization current and the target slip frequency are set to the maximum output torque of the induction motor until the rotational speed of the rotor reaches the target rotational speed. The target slip frequency is set using the map to be matched as follows,
After the rotational speed of the rotor reaches the target rotational speed, the target slip frequency is set using a map that associates the magnetizing current and the target slip frequency so that the power efficiency of the induction motor is maximized. The control device according to claim 3 to set.   The control device according to claim 5, wherein the setting unit switches the map based on a temperature of the induction motor.   The control device according to any one of claims 1 to 8, wherein the induction motor has armature windings having three or more phases as armature windings (13a, 13b).

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