Electrical power converter and control method

• US 7,557,527 B2
• Filed: 05/31/2006
• Issued: 07/07/2009
• Est. Priority Date: 06/01/2005
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Yoshimoto, Kantaro, Maikawa, Kengo, Kitajima, Yasuhiko
• Primary Examiner(s): Patel; T C
• Assistant Examiner(s): MCCLOUD, RENATA D
• Application Number:
  US11/444,161
• Publication Number:
  US 20060273748A1
• Time in Patent Office: 1,133 Days
• Field of Search: 318/434, 318/432, 318/139, 318/800
• US Class Current: 318/432
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: H02M 7/53875 with analogue control of three-phase output
• CPC Class Codes: H02M 7/5388 with asymmetrical configuration of switches
• CPC Class Codes: H02P 21/16 Estimation of constants, e.g. the rotor time constant
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

An electrical power converter comprises a first direct current line connected to a first direct current source, a second direct current line connected to a second direct current source, an alternating current line connected to an alternating current motor, a controller, and a pulse generator. The controller determines a required torque of the alternating current motor. The controller also determines a voltage command value that substantially minimizes a copper loss of the alternating current motor while providing the required torque of the alternating current motor. The pulse generator generates an output voltage according to the voltage command value at the alternating current output.

Claims

1. An electrical power converter comprising:

a first direct current line connected to a first direct current source;

a second direct current line connected to a second direct current source;

an alternating current line connected to an alternating current motor;

a motor torque controller that generates current command values for the alternating current motor and generates compensating voltage command values that correspond to charge target values from the first direct current source to the second direct current source based on a source power command value that commands the charge amount from the first direct current source to the second direct current source, a motor torque command value and a motor rotation speed;

a motor voltage controller that determines motor voltage command values according to the current command values;

a distributed voltage command value generator that determines command values of distributed voltage that the first direct current source and the second direct current source output to the alternating current motor based on a power distributed target value that corresponds respectively to the first direct current source and the second direct current source and the motor voltage command values;

a voltage command value compensator that determines compensating distributed voltage command values by adding the compensating voltage command values to the distributed voltage command values; and

a pulse generator that generates an output voltage at the alternating current output according to the compensating distributed command values.

2. The electrical power converter of claim 1, wherein

the motor torque controller selects the current command value of the alternating current motor and the compensating voltage command values from the source power command value, the motor torque command value, the motor rotation speed and by referencing a predefined map.

3. The electrical power converter of claim 1, wherein

the motor torque controller selects the current command value for the alternating current motor that provides no torque for the alternating current motor when either the motor torque command value or the motor rotation speed is zero or near zero.

4. The electrical power converter of claim 3, wherein

the motor torque controller selects the current command value of the alternating current motor and selects the compensating voltage command value such that a motor loss of the alternating current motor is minimized when either the motor torque command value or the motor rotation speed is zero or near zero.

5. The electrical power converter of claim 4, wherein

the motor torque controller selects the current command value of the alternating current motor and selects the compensating voltage command value such that a power loss of the alternating current motor is minimized, and

the motor torque controller selects the current command value of the alternating current motor and selects the compensating voltage command value according to a inductance value of the alternating current motor, a carrier frequency, and the source power command value.

6. The electrical power converter of claim 5, wherein the current command value of the alternating current motor is

${\mathrm{Id}}^{*}=-\frac{\sqrt{{\mathrm{Pb}}^{*}}}{\sqrt{2}}$

2 ⁢

L d ⁢

f c ,

the compensating voltage command value is

$V_{d_{-}<br><br>0}*=-\sqrt{2<br><br>\sqrt{2}<br><br>L_d<br><br>f_c<br><br>\mathrm{Pb}*},<br><br>\mathrm{and}$

Id* represents a d axis current command value, Vd_—

0* represents a compensating voltage command value, Pb* represents a source power command value, Ld represents a motor d axis inductance value, and fc represents a carrier frequency.

7. The electrical power converter of claim 3, further comprising

a motor loss command generator that generates a motor loss command value;

and

a loss calculator that calculates a motor loss,

wherein the motor current command value generator selects a current command value of the alternating current motor and selects a compensating voltage command value such that the motor loss matches the motor loss command value.

8. The electrical power converter of claim 1, wherein

the motor torque controller selects the compensating voltage command value to be a dq axis compensating voltage command value,

the motor voltage controller determines a dq axis motor voltage command value according to a dq axis current command value,

the voltage command value compensator obtains a dq axis distributed voltage command value by calculating the product of a power distribution ratio command value and the dq axis motor voltage command value, and

the voltage command value compensator calculates a dq axis compensating voltage command value.

9. The electrical power converter of claim 1, wherein

the voltage command value compensator calculates a modulation factor compensating value from a modulation factor command value by normalizing a compensating distributed voltage command value according to a source voltage value of the first direct current source, a source voltage value of the second direct current source, and a power distribution ratio command value,

the voltage command value compensator determining the compensating voltage command value, according to the value of the calculated modulation factor compensating value from the modulation factor command value.

10. The electrical power converter of claim 1, further comprising

a can voltage command value compensator,

wherein the can voltage command value compensator calculates a modulation factor command value that normalized the distributed voltage command value to a source voltage value of the first direct current source,

the can voltage command value compensator calculates a modulation factor compensating value from the source voltage values of the first direct current source and the second direct current source and the distributed voltage command value, and

the voltage command value compensator determines the compensating distributed voltage command value based on the modulation factor compensation value and the modulation factor command value.

11. The electrical power converter of claim 1, wherein

the first direct current source is a fuel cell, and the second direct current source is a battery.

12. An electrical power converter comprising:

a first direct current line connected to a first direct current source;

a second direct current line connected to a second direct current source;

an alternating current line that drives an alternating current motor;

a motor torque control means that generates current command values for the alternating current motor and generates compensating voltage command values that correspond to charge target values from the first direct current source to the second direct current source based on a source power command value that commands the charge amount from the first direct current source to the second direct current source, a motor torque command value and a motor rotation speed;

a motor voltage control means that determines motor voltage command values according to the current command values;

a distributed voltage command value calculation means that generates command values of distributed voltage that the first direct current source and the second direct current source output to the alternating current motor based on a power distributed target value that corresponds respectively to the first direct current source and the second direct current source and the motor voltage command values;

a voltage command value compensate means that determines compensating distributed voltage command values by adding the compensating voltage command values to the distributed voltage command values; and

a pulse generate means that generates an output voltage at the alternating current output according to the compensating distributed command values.

13. A method of controlling an electrical power converter comprising:

generating current command values for an alternating current motor;

generating compensating voltage command values that correspond to charge target values from a first direct current source to a second direct current source based on a source power command value that commands the charge amount from the first direct current source to the second direct current source, a motor torque command value and a motor rotation speed;

determining motor voltage command values according to the current command values;

generating command values of distributed voltage that the first direct current source and the second direct current source output to the alternating current motor based on a power distributed target value that corresponds respectively to the first direct current source and the second direct current source and the motor voltage command values;

determining compensating distributed voltage command values by adding the compensating voltage command values to the distributed voltage command values; and

generating an output voltage to power the alternating current motor according to the compensating distributed command values.

14. The method of claim 13, wherein

the electrical power converter generates a driving voltage for the alternating current motor by generating and synthesizing pulses from any of the respective output voltages of the first direct current source and the second direct current source.