Synchronous motor control device electric motor vehicle control device and method of controlling synchronous motor

• US 6,281,656 B1
• Filed: 09/30/1999
• Issued: 08/28/2001
• Est. Priority Date: 09/30/1998
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kaneko, Satoru, Masaki, Ryoso
• Primary Examiner(s): Nappi, Robert E.
• Assistant Examiner(s): SMITH, TYRONE W
• Application Number:
  US09/409,992
• Time in Patent Office: 698 Days
• Field of Search: 318/701, 318/700, 318/804, 318/805, 318/807
• US Class Current: 318/700
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2220/14 Synchronous machines
• CPC Class Codes: B60L 2220/16 DC brushless machines
• CPC Class Codes: B60L 2220/18 Reluctance machines
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 50/60 using power supplied by batteries in combination with fuel cells B60L50/75
• CPC Class Codes: H02P 6/18 without separate position detecting elements
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A synchronous motor control system includes a synchronous motor 1, an inverter 3 and a controller 4 wherein a current differential detecting unit 13 detects a variation of a motor current when the three phases of the motor 1 is short circuited by the inverter 3, namely at the moment when a carrier wave in a PWM signal generator 9 assumes maximum or minimum value, in a calculating unit 14 a phase γ from α axis of a stationary coordinate system to a three phase short circuited current differential vector is calculated, a phase δ is estimated from d axis to the three phase short circuited current differential vector by making use of d axis current id and q axis current iq on d-q axes coordinate system in the controller 4, thereafter the magnetic pole position θ with respect to α axis is calculated from the phases γ and δ, based on thus calculated magnetic pole position θ, d-q axes control units 11, 7 and 8 are constituted to control the synchronous motor, thereby a highly reliable control system for the motor which permits a detection of the magnetic pole position without affecting a state of applied voltage thereto while performing a usual PWM control with a low cost controller.

Claims

1. A device for controlling a three phase synchronous, motor comprising:

a controller which generates PWM signals based on three phase voltage command values; and

an inverter which drives said three phase synchronous motor with the PWM signals;

wherein said controller

detects a motor current in synchronism with a PWM signal of a phase having an intermediate voltage command value among the three phase voltage command values;

detects a magnetic pole position of said three phase synchronous motor based on the detected current; and

determines the three phase voltage command values depending on the detected magnetic pole position.

2. A device for controlling a synchronous motor, comprising:

an inverter which drives said synchronous motor; and

a controller which detects a magnetic pole position of said synchronous motor based on a variation of a motor current when said synchronous motor is put in a short circuited state, and outputs a control signal to control said synchronous motor based on the detected magnetic pole position, wherein said inverter controls said synchronous motor based on the control signal;

wherein said controller judges an abnormality in the synchronous motor control device through comparison of a first motor speed obtained from a variation state of the detected magnetic pole position with a second motor speed obtained from the variation amount of the motor.

3. A device for controlling a synchronous motor control device comprising:

an inverter which drives said synchronous motor; and

a controller which detects a magnetic pole position of said synchronous motor based on a variation direction of a motor current when said synchronous motor is put in a short circuited state, and generates a control signal to control said synchronous motor based on the detected magnetic pole position, wherein said inverter controls said synchronous motor based on the control signal;

wherein said controller judges an abnormality in the synchronous motor control device through comparison of a first motor speed obtained from a variation state of the detected magnetic pole position with a second motor speed obtained from the variation amount of the motor control.

4. A device for controlling a synchronous motor control device comprising:

an inverter which drives said synchronous motor and a controller which generates a control signal, wherein said inverter drives said synchronous motor based on the control signal generated by said controller; and

said controller which detects a variation direction of a motor current when said synchronous motor is in a short circuited state, sets a d-q axes coordinate system while assuming the magnetic flux direction of a rotor of said synchronous motor as d axis and an axis orthogonal to the d axis as q axis, detects a d axis current and a q axis current on the d-q axes coordinate system, calculates the magnetic pole position of said synchronous motor based on the detected variation direction of the motor current, the detected d axis current and the detected q axis current and generates the control signal depending on the calculated magnetic pole position;

wherein said controller judges an abnormality in the synchronous motor control device through comparison of a first motor speed obtained from a variation state of the detected magnetic pole position with a second motor speed obtained from the variation amount of the motor current.

5. A device for controlling a synchronous motors, comprising:

a magnetic pole position detector which detects a magnetic pole position of said synchronous motor;

a controller which controls said synchronous motor depending on the magnetic pole position detected by said magnetic pole position detector; and

an inverter which drives said synchronous motor based on a signal from said controller,

wherein said controller determines the magnetic pole position of said synchronous motor based on a variation amount or a variation direction of a motor current when said synchronous motor is in a short circuited state and detects an abnormality in said magnetic pole position detector or the controller through comparison of the magnetic pole position detected by the magnetic pole position detector with the magnetic pole position obtained from the variation amount or the variation direction of the motor current.

6. An electric motor vehicle control device comprising:

a synchronous motor which drives the electric motor vehicle;

a magnetic pole position detector which detects a magnetic pole position of said synchronous motor;

a controller which controls said synchronous motor depending on the magnetic pole position detected by said magnetic pole position detector; and

an inverter which drives said synchronous motor based on a signal from said controller,

wherein said controller determines the magnetic pole position of said synchronous motor based on a variation amount or a variation direction of a motor current when said synchronous motor is placed in a short circuited state and detects an abnormality in said magnetic pole position detector or the controller through comparison of the magnetic pole position detected by the magnetic pole position detector with the magnetic pole position obtained from the variation amount or the variation direction of the motor current; and

wherein after stopping the electric motor vehicle, said controller restarts a drive of the electric motor vehicle by making use of a normal magnetic pole position among the magnetic pole position obtained from magnetic pole position detector and the magnetic pole position obtained from the motor current through said controller determined as normal.

7. A synchronous motor control method comprising:

a first step of detecting a variation direction of a motor current when a synchronous motor is in a short circuited state;

a second step of setting a d-q axes coordinate system, assuming the magnetic flux direction of a rotor of the synchronous motor as d axis and an axis orthogonal to the d axis as q axis;

a third step of detecting a d axis current and a q axis current on the d-q axes coordinate system;

a fourth step of calculating the magnetic pole position of the synchronous motor based on the detected variation direction of the motor current, the detected d axis current and the detected q axis current; and

a fifth step of controlling the synchronous motor depending on the calculated magnetic pole position.

8. A synchronous motor control method according to claim 7, wherein when a difference between the magnetic pole position on the d-q axes coordinate system set in said second step and the magnetic pole position calculated in said fourth step is in a predetermined range, the synchronous motor is controlled based on the magnetic pole position calculated in said fourth step.