Compressor drive system

• US 5,123,080 A
• Filed: 01/08/1990
• Issued: 06/16/1992
• Est. Priority Date: 03/20/1987
• Status: Expired due to Fees

• Current Assignee: Ranco Incorporated of Delaware (Schneider Electric SE)
• Original Assignee: Ranco Incorporated of Delaware (Schneider Electric SE)
• Inventors: Ingram, Charles B., Gillett, Jimmie D., Garcia, Richard R.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Martin, David
• Application Number:
  US07/462,569
• Time in Patent Office: 890 Days
• Field of Search: 318/798-811, 388/810, 388/811, 388/819, 388/829, 388/831, 388/934, 62/228.3, 62/278.4, 62/229, 62/226, 62/227, 62/213, 417/45
• US Class Current: 388/811
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: F25B 49/025 Motor control arrangements
• CPC Class Codes: G05D 23/1906 using an analogue comparing device
• CPC Class Codes: G05D 23/22 the sensing element being a thermocouple
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A compressor drive system that includes a thermostat producing a signal indicating the measured air temperature, a modulation control circuit connected to the thermostat to produce a motor drive signal from the temperature signal and which is output to a motor drive switching bridge circuit. The motor drive switching bridge circuit is connected to a rectifier that converts single phase alternating current to direct current. The switching bridge uses the motor drive signal from the modulation control circuit and the rectifier output to produce multiphase power including a speed control signal imposed on the power for regulating speed. A motor connected to drive a compressor is included. The motor is powered by the motor drive switching bridge circuit multiphase power output. The speed of the motor is controlled as a function of the temperature signal.

Claims

1. A drive system for energizing a multi-phase motor comprising:

rectifier means for converting an externally supplied single phase alternating current signal into a direct current signal;

control voltage means for receiving a temperature signal and producing a motor speed signal in response thereto;

oscillator means for receiving the motor speed signal and producing first and second waveform signals in response thereto;

frequency modulation circuit means for receiving the first waveform signal and producing a third waveform signal and multi-phase power control signals;

comparator means for combining the second and third waveform signals and the speed signal to produce a speed control waveform signal;

modulation circuit means for combining the multi-phase power control signals with the speed control waveform signal to produce multi-phase modulated power control signals;

a motor drive switching bridge circuit operatively connected to the rectifier means and the modulation circuit means for producing multi-phase motor energization signals, said switching bridge circuit including a plurality of switching power transistors for producing preselected voltages, a corresponding plurality of control circuits operatively connected to the plurality of switching power transistors, said plurality of switching power transistors responsive to the plurality of control circuits for substantially quick saturation and to the plurality of control circuits for substantially quick turnoff, whereby the leading and trailing edges of square wave motor energization signals are enhanced; and

output means for coupling the motor drive switching bridge to a multi-phase motor for multi-phase operation of said motor.

2. A drive system according to claim 1 wherein said control voltage means further includes a current limiting circuit for receiving a current signal indicating a rectifier current output for modulating the motor speed signal in response to the rectifier current output.

3. A drive system according to claim 1 wherein said comparator means further includes a voltage regulation circuit for receiving a signal indicating the voltage output from the rectifier and modulating the speed signal in response thereto.

4. A drive system according to claim 1 wherein said control voltage means further includes circuit means to provide an initial start voltage signal providing an increased power output from the motor drive switching bridge circuit to start the motor.

5. A drive system according to claim 1 and further including fault detection means connected to the frequency modulation circuit means for prohibiting the production of the multi-phase modulated power control signals in the presence of a fault condition.

6. A drive system according to claim 5 wherein said fault detection means further includes a fault detection latch that is set upon the occurrence of a fault condition resulting in the inhibiting of the production of multi-phase modulated power control signals until reset by an external reset signal.

7. A drive system according to claim 5 wherein the fault detection means further includes an overcurrent circuit means for setting the fault detection latch when the current output from the motor drive switching bridge circuit means exceeds a predetermined value.

8. A drive system according to claim 6 wherein said fault detection means further includes an undervoltage/overvoltage detection circuit for providing an input to the fault detection latch when the voltage output from the rectifier exceeds a first voltage value or is less than a second voltage value.

9. A drive system according to claim 6 wherein said fault detection means further includes a ground fault circuit means for detecting excessive current output from the rectifier means and for providing an input to the fault detection latch in response thereto.

10. A drive system according to claim 1 wherein the rectifier means further includes an input filter to reduce any electromagnetic interference from the externally supplied alternating current signal.