Control device for commutatorless motor

• US 4,276,504 A
• Filed: 12/20/1978
• Issued: 06/30/1981
• Est. Priority Date: 02/03/1978
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nagase, Hiroshi, Okuyama, Toshiaki, Kubota, Yuzuru
• Primary Examiner(s): Rubinson, Gene Z.
• Application Number:
  US05/971,270
• Time in Patent Office: 923 Days
• Field of Search: 318/138, 318/720-723, 318/799-803, 318/807-812
• US Class Current: 318/721
• CPC Class Codes: H02P 1/46 for starting an individual synchronous motor H02P27/04 takes precedence
• CPC Class Codes: H02P 25/03 with brushless excitation

Abstract

A control device for a thyristor motor is disclosed by which the advance angle is switched at a predetermined slow rate of change in order to avoid an abrupt change in the motor torque. The thyristor motor comprises a thyristor frequency converter for a frequency conversion and a synchronous motor driven by the frequency converter, and in the thyristor motor the advance angle is switched at low and high speeds of the motor.

Claims

1. An advance angle control apparatus for a commutatorless motor, comprising

frequency converter means including a plurality of thyristors for converting a frequency in order to supply an AC power to armature windings of a synchronous motor,

a position detector for detecting the position of the rotor of said synchronous motor,

a speed detector for detecting an actual speed of said synchronous motor,

a speed control means including a first gate pulse generator for controlling the firing phase of said thyristors in accordance with a signal obtained by comparing the actual speed with a command speed,

a second gate pulse generator for generating signals controlling the gates of said thyristors in accordance with the output of said position detector, and

an advance angle control command circuit applied with the output of said speed detector,

for outputting to said second gate pulse generator a signal with a low value for an advance angle at a low speed of said synchronous motor and a high value for the advance angle at a high speed, said advance angle control command circuit comprising a comparator for comparing the actual speed value with a reference value provided by a speed setting circuit, and a change regulating circuit applied with the output of said comparator for regulating a change between advance angle control command signals at the low speed and the high speed during a predetermined time interval, and the output of which is applied to said second gate pulse generator as the advance angle control command signals, said comparator switching its output signal from a constant value to another constant value when the actual speed value reaches a predetermined speed value.

2. An advance angle control apparatus according to claim 1 wherein said change regulating circuit is a first-order delay member.

3. An advance angle control apparatus according to claim 1, wherein said change regulating circuit is an integration circuit with an output signal limitation.

4. In a control device for a commutatorless motor, having a thyristor power converter to supply power to said motor, control means to supply control signals to the gate of the thyristor of the power converter, generator means to supply to the control means a signal whose advance angle is variable when the motor runs at a speed higher than a predetermined speed, wherein the improvement comprises:

an advance angle control means for regulating the change in said advance angle independent of the rate of change of said motor speed.

5. The improved control device of claim 4 wherein said advance angle control means comprises a comparator for comparing the actual speed value with a reference value provided by a speed setting circuit and a change regulating means supplied with the output of said comparator for regulating a change between the advance angle control command signals at a low speed and the high speed during a predetermined time interval.

6. The improved control device of claim 5, wherein said change regulating means is a first-order delay member.

7. The improved control device of claim 5, wherein said change regulating circuit is an integration circuit with an output signal limitation.