Motor starting circuit

Abstract

An electronic starting circuit for a single-phase electric motor is disclosed in which the motor has a first, and possibly a second, main winding and has an auxiliary winding used for starting. The voltage across the auxiliary winding increases as the motor speed accelerates and is used as a sensing signal. This signal is applied through an amplifier to a peak detector which determines the peak DC output and compares it with a reference voltage. When the reference voltage is the larger, then an auxiliary switch connected in series with the motor auxiliary winding is closed for starting of the motor. When the peak DC output voltage from the peak detector exceeds the reference voltage, the auxiliary switch is opened. Instant reversing of the motor is possible by discharging a capacitor in the peak detector at the time of reversal so as to re-energize the auxiliary winding. The circuit also operates on a two-speed motor. The motor starts on the high-speed main winding, and then transfers to the low-speed main winding if low speed is selected. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.