Control unit for controlling a synchronous motor

• US 6,960,898 B2
• Filed: 09/17/2004
• Issued: 11/01/2005
• Est. Priority Date: 10/27/2003
• Status: Active Grant

• Current Assignee: Fuji Electric Company Limited (Fuji Electric Systems Company Limited)
• Original Assignee: Fuji Electric Systems Company Limited
• Inventors: Sato, Yoshinobu
• Primary Examiner(s): Fletcher, Marlon T.
• Assistant Examiner(s): SMITH, TYRONE W
• Application Number:
  US10/942,943
• Publication Number:
  US 20050088135A1
• Time in Patent Office: 410 Days
• Field of Search: 318700-779, 318/138, 318/254, 318430-434, 318/439, 318/453, 318/459, 318/471, 318/474, 318/560
• US Class Current: 318/400.26
• 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 2207/05 Synchronous machines, e.g. with permanent magnets or DC excitation
• CPC Class Codes: H02P 27/047 V/F converter, wherein the voltage is controlled proportionally with the frequency
• CPC Class Codes: H02P 29/032 Preventing damage to the motor, e.g. setting individual current limits for different drive conditions

Abstract

A control unit is provided that controls a motor that opens and closes a door of an electric train such that, if an abnormality is detected by a position sensor, continuation of its open/closing operation can be maintained. The control unit includes an arrangement for computing the actual rotation speed and the magnetic polar position of the motor; a position sensor abnormality-detecting identifier unit for detecting abnormalities in the output of the position sensor; and a first controlling arrangement that generates voltage-instructing values by applying the magnetic polar position so as to cause a speed detection value to correspond to the speed instruction value. The control unit further includes a second controlling arrangement, which in turn includes an F/V arithmetic unit 24 and integrator 25; and a switcher unit 27. The F/V arithmetic unit 24 generates a voltage instruction value having a specific magnitude and phase corresponding to the speed instruction value by utilization of magnetic polar position data that is obtained via integration of a frequency corresponding to the speed instruction value. The switcher unit 27 selects either of the first and second controlling arrangements so as to generate voltage-instructing values for a power converter 3. When the output of the position sensor is normal, the switcher unit 27 selects a specific voltage-instructing value delivered from the first controlling arrangement, whereas if the position of the sensor 5 is abnormal, the switcher unit 27 selects a specific voltage-instructing value delivered from the second controlling arrangement.

Claims

1. A control unit for controlling a permanent-magnet-type synchronous motor incorporating a position sensor, the motor being connected to a power converter, comprising:

a motor speed unit for determining the rotational speed of said motor based on a signal output from said position sensor;

a motor position unit for determining a magnetic polar position of said motor based on the signal output from said position sensor;

a position-sensor abnormality identifier means for detecting abnormalities in the signal output from said position sensor;

a first controlling means for generating voltage-instructing values for said power converter by utilizing the magnetic polar position determined by the motor position unit so as to cause a motor speed detection value detected by said motor speed unit to pursue a speed instruction value;

a second controlling means for generating voltage-instructing values having a magnitude and a phase corresponding to said speed instruction value by employing a magnetic polar position based on a frequency corresponding to said speed instruction value; and

a switching means for selecting either said first controlling means or said second controlling means so as to transmit voltage-instructing values generated by either of said controlling means to said power converter,

wherein, when said position-sensor abnormality identifier detects that the signal output from said position sensor is normal, said switching means transmits voltage-instructing values from said first controlling means to said power converter and when said position-sensor abnormality identifier detects that the signal output from said position sensor is abnormal, said switching means transmits voltage-instructing values from said second controlling means to said power converter.

2. A control unit for according to claim 1, wherein

said motor drives a door so as to enable the door to open and close,

when the signal output from said position sensor is identified as normal, the supply of power to said motor is halted when said door is fully open and fully closed, and

when the signal output from said position sensor is identified as abnormal, it causes the supply of power to said motor to be continued, except for cases in which said door remains fully closed.

3. A control unit for according to claim 1, wherein

said motor drives a door so as to enable the door to open and close,

said control unit further comprises a detector that detects when said door is fully closed, and a memory for memorizing the actual door position when the signal output from said position sensor is identified as normal and said detector has detected that said door has been fully closed, and

when the signal output from said position sensor has been identified as abnormal and said detector has detected that said door has been fully closed, said motor drives said door so as to enable it to open and close by referring to the door position memorized in said memory.