Method and apparatus for controlling a synchronous motor

• US 5,880,570 A
• Filed: 05/21/1996
• Issued: 03/09/1999
• Est. Priority Date: 05/24/1995
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Kondo, Yasuhiro, Tamaki, Satoshi, Ikkai, Yasufumi
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): LOCKETT, KIMBERLY R
• Application Number:
  US08/651,134
• Time in Patent Office: 1,022 Days
• Field of Search: 318/720, 318/700, 318/721, 318/722, 318/811, 318/723, 318/803, 318/724, 318/432, 318/139, 318/52, 318/801
• US Class Current: 318/700
• CPC Class Codes: B60L 15/08 using pulses
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 2220/14 Synchronous machines
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

An inverter(3) for driving a motor(4) of an electric automobile(20) produces a three-phase PWM current. When the torque reference is zero, alternatively or when the torque reference is zero and motor speed is no higher than a predetermined value, the inverter(3) is controlled to be cut off so that current from a main power battery(9) is suspended or stopped.

Claims

1. An improved method of controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising the steps of:

obtaining an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtaining a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtaining a speed feedback signal representative of a speed of the motor;

obtaining a current feedback signal representative of a current of the motor;

processing the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference;

producing a pulse width modulation (PWM) output signal based on the torque reference, the PWM output signal being applied to control the inverter;

suspending switching operation of the inverter when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is less than a first predetermined value, thereby stopping current flow from the battery to said motor of the electric automobile; and

supplying a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than a second predetermined value.

9. The improved method of claim 1, comprising the step of:

supplying a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than the first predetermined value.

2. An improved method of controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising the steps of:

obtaining an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtaining a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtaining a speed feedback signal representative of a speed of the motor;

obtaining a current feedback signal representative of a current of the motor;

processing the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference;

producing a pulse width modulation (PWM) output signal based on the torque reference, the PWM output signal being applied to control the inverter;

suspending switching operation of the inverter when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is less than a first predetermined long-time-low-speed reference value for a predetermined time length, thereby stopping current flow from the battery to said motor of the electric automobile; and

supplying a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than a second predetermined value.

3. An improved apparatus for controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising:

a control apparatus including a CPU which;

obtains an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtains a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtains a speed feedback signal representative of a speed of the motor;

obtains a current feedback signal representative of a current of the motor;

processes the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference, a pulse width modulation (PWM) output signal being produced based on the torque reference, the PWM output signal being applied to control the inverter;

suspends switching operation of the inverter when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is less than a first predetermined value, thereby stopping current flow from the battery to said motor of the electric automobile; and

supplies a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than a second predetermined value.

4. An improved apparatus for controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising:

a control apparatus including a CPU which;

obtains an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtains a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtains a speed feedback signal representative of a speed of the motor;

obtains a current feedback signal representative of a current of the motor;

processes the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference, a pulse width modulation (PWM) output signal being produced based on the torque reference, the PWM output signal being applied to control the inverter;

suspends switching operation of the inverter when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is less than a first predetermined long-time-low-speed reference value for a predetermined time length, thereby stopping current flow from the battery to said motor of the electric automobile; and

supplies a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than a second predetermined value.

5. An improved method of controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising the steps of:

obtaining an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtaining a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtaining a speed feedback signal representative of a speed of the motor;

obtaining a current feedback signal representative of a current of the motor;

processing the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference;

producing a current from the battery based on the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal, the current being applied to the inverter;

suspending switching operation of the inverter when the torque reference is zero, thereby stopping current flow from the battery to said motor of the electric automobile; and

supplying a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than a predetermined value.

6. An improved method of controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising the steps of:

obtaining an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtaining a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtaining a speed feedback signal representative of a speed of the motor;

obtaining a current feedback signal representative of a current of the motor;

processing the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference;

producing a current from the battery based on the acceleration pedal pushing-down degree signal, the current being applied to the inverter;

suspending switching operation of the inverter when the torque reference is zero, thereby stopping current flow from the battery to said motor of the electric motor.

7. An improved method of controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising the steps of:

obtaining an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtaining a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtaining a speed feedback signal representative of a speed of the motor;

obtaining a current feedback signal representative of a current of the motor;

processing the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference;

producing a current from the battery based on the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal, the current being applied to the inverter;

suspending switching operation of the inverter when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is less than a first predetermined value, thereby stopping current flow from the battery to said motor of the electric automobile; and

supplying a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than a second predetermined value.

8. An improved method of controlling a synchronous motor of an electric automobile, the motor being driven by a pulse width modulated current fed from at least one battery through an inverter, the improvement comprising the steps of:

obtaining an acceleration pedal pushing-down degree signal representative of a degree to which an acceleration pedal of the automobile is pushed down;

obtaining a brake pedal pushing-down degree signal representative of a degree to which a brake pedal of the automobile is pushed down;

obtaining a speed feedback signal representative of a speed of the motor;

obtaining a current feedback signal representative of a current of the motor;

processing the acceleration pedal pushing-down degree signal, the brake pedal pushing-down degree signal, the speed feedback signal, and the current feedback signal to produce a torque reference;

producing a current from the battery based on the acceleration pedal pushing-down degree signal, the current being applied to the inverter;

suspending switching operation of the inverter when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is less than a first predetermined value, thereby stopping current flow from the battery to said motor of the electric automobile; and

supplying a current produced by the motor by regenerative braking to the battery when the torque reference is zero and the speed feedback signal indicates that the speed of the motor is greater than a second predetermined value.