Electric power converter, electric power converter controlling method and electric power converting system

• US 20070159121A1
• Filed: 01/11/2007
• Published: 07/12/2007
• Est. Priority Date: 01/12/2006
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Yoshimoto, Kantaro, Maikawa, Kengo
• Granted Patent: US 7,598,692 B2
• Time in Patent Office: Days
• US Class Current: 318/140
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters
• CPC Class Codes: H02P 21/00 Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
• CPC Class Codes: H02P 23/26 Power factor control [PFC]
• CPC Class Codes: H02P 27/16 using ac to ac converters without intermediate conversion to dc H02P27/05 takes precedence

Abstract

An electric power converter, electric power converter controlling method and electric power converting system for converting multi-phase alternating-current inputted from a generator and outputting multi-phase alternating current for controlling a drive of a motor. An input power factor commanding section outputs a command value of an input power factor according to an operating condition of the motor, and an input power factor controlling section controls the input power factor of the generator on the basis of the command value of the input power factor from the input power factor commanding section.

Claims

1. A control unit for controlling an electric power converter, the electric power converter converting multi-phase alternating current inputted from a generator and supplying the converted current to a motor, the control unit comprising:

an input power factor commanding section operable to output an input power factor command value for an input power factor of the generator according to an operating condition of the motor; and

an input power factor controlling section operable to output a control signal to the electric power converter, the control signal for controlling the input power factor and based on the input power factor command value.

2. The control unit according to claim 1 wherein the input power factor commanding section is further operable to calculate the input power factor command value according to a required voltage of the motor, the required voltage being based on an output torque command value of the motor and an output rotation angular speed of the motor.

3. A control unit according to claim 2 wherein the input power factor commanding section is further operable to apply the required voltage and to calculate the input power factor of minimizing the input current as the command value.

4. A control unit according to claim 1 wherein the input power factor controlling section is further operable to generate a drive voltage command to satisfy an output voltage command of the motor by synthesizing output voltages of two virtual direct current voltage sources, which correspond to a respective instantaneous input voltage value of an input voltage of the multi-phase alternating current from the generator;

and wherein the input power factor controlling section is further operable to control the input power factor by varying a voltage distribution ratio of the two virtual direct current voltage sources.

5. A control unit according to claim 4 wherein the input power factor controlling section further comprises:

an input voltage determining section operable to generate the respective input voltage value and a mode signal indicative of a condition of the input voltage based on a magnitude relation of the input voltage values;

an output voltage calculating section operable to calculate the output voltage command based on an output torque command value of the motor and an output rotation angular speed of the motor;

a virtual PWM signal generating section operable to generate a virtual PWM signal of a switch when a drive voltage satisfies the output voltage command by generating and synthesizing a pulse by a predetermined voltage distribution ratio between respective output voltages of the two virtual direct-current voltage sources;

a voltage distribution ratio calculating section operable to calculate a voltage distribution ratio from the input voltage and the input power factor command value; and

a signal synthesizing section operable to generate the control signal wherein the control signal is a synthesized PWM signal from the mode signal and the virtual PWM signal.

6. The control unit according to claim 5 wherein the virtual PWM signal generating section further comprises:

a voltage command value calculating section operable to generate a voltage command value of each respective input voltage value based on a product of the output voltage command and the voltage distribution ratio; and

a regulated voltage commanding section operable to generate a regulated voltage command obtained by regulating the voltage command value of each respective input voltage value with respect to the corresponding input voltage; and

wherein the virtual PWM signal generating section is further operable to generate the virtual PWM signal by executing a triangular wave comparison PWM control of the regulated voltage command.

7. The control unit according to claim 6 wherein the signal synthesizing section further comprises a map representing a relationship between the virtual PWM signal and the mode signal.

8. The control unit according to claim 1 wherein the input power factor commanding section further comprises:

a coordinate converting section operable to generate a conversion current by executing a coordinate conversion of the input current;

a conversion current command calculating section operable to generate a conversion current command value; and

a compensating section operable to adjust the input power factor command value based on a difference between the conversion current and the conversion current command value.

9. The control unit according to claim 8 wherein the conversion current command calculating section is further operable to generate the conversion current command value based on a product of an amplitude of the input current and a trigonometric function of the power factor command value.

10. The control unit according to claim 1 wherein the input power factor commanding section further comprises:

a coordinate converting section operable to generate a conversion current by executing a coordinate conversion of the input current;

a conversion current command calculating section operable to generate a conversion current command value;

a compensating section operable to calculate an adjustment value for the input power factor command value on the basis of a difference between the conversion current and the conversion current command value; and

a correcting section operable to correct the input power factor command value based on a sum of the input power factor command value and the adjustment value.

11. The control unit according to claim 1 wherein the control signal includes an ON/OFF signal output to each of a first switch connecting R-phase and U-phase of the electric power converter, a second switch connecting S-phase and the U-phase of the electric power converter, a third switch connecting T-phase and the U-phase of the electric power converter, a fourth switch connecting the R-phase and V-phase of the electric power converter, a fifth switch connecting S-phase and the V-phase of the electric power converter, a sixth switch connecting the T-phase and the V-phase of the electric power converter, a seventh switch connecting the R-phase and W-phase of the electric power converter, an eighth switch connecting the R-phase and the W-phase of the electric power converter, and a ninth switch connecting the T-phase and the W-phase of the electric power converter.

12. An electric power converting system comprising:

a generator operable to generate multi-phase alternating current;

a motor driven by the multi-phase alternating current;

an electric power converter connected to the generator and the motor; and

a control unit for controlling the electric power converter, the control unit including;

an input power factor commanding section operable to generate an input power factor command value for an input power factor of the generator, the input power factor command value based on an operating condition of the motor; and

an input power factor controlling section operable to output a control signal to the electric power converter for controlling the input power factor based on the input power factor command value.

13. The electric power converting system according to claim 12 wherein the input power factor commanding section is further operable to calculate the input power factor command value according to a required voltage of the motor.

14. The electric power converting system according to claim 12 wherein the input power factor controlling section is further operable to apply the required voltage by minimizing the input current in response to the input power factor command value.

15. The electric power converting system according to claim 12 wherein the input power factor controlling section further comprises:

an input voltage determining section operable to generate an input voltage value and a mode signal based on a voltage of the multi-phase alternating current from the generator;

an output voltage calculating section operable to calculate an output voltage command value based on an output torque command value and an output rotation angular speed of the motor;

a voltage distribution ratio calculating section operable to calculate a voltage distribution ratio based on the input voltage value and the input power factor command value;

a virtual PWM signal generating section operable to generate a virtual PWM signal for each of two virtual direct current voltage sources based on the voltage distribution ratio; and

a signal synthesizing section operable to generate the control signal as a synthesized PWM signal based on the mode signal and the virtual PWM signals.

16. The electric power converting system according to claim 12 wherein the input power factor commanding section further comprises:

a coordinate converting section operable to generate a conversion current by executing a coordinate conversion of the input current;

a conversion current command calculating section operable to generate a conversion current command value; and

a compensating section operable to adjust the input power factor command value based on a difference between the conversion current and the conversion current command value.

17. A method for controlling an electric power converter, wherein the electric power converter receives multi-phase alternating current input current from a generator and supplies converted output current to a motor, the method comprising:

determining an input power factor command value for the input power factor of the generator, the input power factor command value based on an operating condition of the motor; and

outputting a control signal to the electric power converter for controlling the input power factor of the generator based on the input power factor command value.

18. The method according to claim 17 wherein determining an input power factor command value further comprises:

calculating the input power factor command value according to a required voltage of the motor, the required voltage being based on an output torque command value of the motor and an output rotation angular speed of the motor.

19. A method according to claim 17 wherein the input power factor commanding section is further operable to apply the required voltage and to calculate the input power factor of minimizing the input current as the command value.

20. The method 17, further comprising:

generating a conversion current by executing a coordinate conversion of the input current from the generator;

generating a conversion current command value;

calculating an adjustment value for the input power factor command value based on a difference between the conversion current and the conversion current command value; and

correcting the input power factor command value based on a sum of the input power factor command value and the adjustment value.