Abstract:
An AC motor is energized by the output voltage of an inverter which in turn receives a DC input voltage from a DC-to-DC converter. A combined oscillator-regulator circuit includes a first potentiometer for adjusting the desired volts/hertz ratio of the inverter output voltage, and a second potentiometer for regulating motor speed. The combined oscillator-regulator receives an output signal from the inverter for comparison against the desired volts/hertz ratio signal, and provides two control signals. The first control signal regulates the operation of the DC-to-DC converter, and the second control signal regulates the frequency of the inverter output voltage.
Abstract:
A motor control system including conventional components such as a volts/Hertz regulator to modify the inverter voltage amplitude, a logic stage to regulate inverter voltage frequency, and an oscillator for supplying timing pulses for the logic stage. To compensate undesired ''''cogging'''' at low operating frequencies, a square wave signal is produced and then integrated. An additional circuit is provided to incorporate additional phase shift in the signal which modulates the voltage passed from the inverter to the motor to prevent cogging. As the frequency of system operation increases, integration of the correction signal provides a modulating signal of decreasing amplitude. Thus the anticogging circuit is only effective at the lower end of the system operating range.