Variable-speed drive for single-phase asynchronous motors
AssigneeHorstmann Systems Corporation
InventorManfred Horstmann
Life of this patent
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Abstract
A frequency converter circuit is disclosed for controlling the speed of a single-phase asynchronous motor wherein the controlled speed keeps the slip between the speed of a driving magnetic field and a speed of a motor rotor as small as possible. Voltage and frequency are provided by the frequency converter circuit wherein a current is provided using the characteristics of the motor and its load mechanically connected to the shaft. By utilizing this current the lowest possible slip results in the maximum possible efficiency at the required operating point of the motor.
Claims12
A control circuit for controlling a single-phase AC motor, comprising:
- a quadrature oscillator configured to output a first sinusoidal signal and a second sinusoidal signal, the first sinusoidal signal and the second sinusoidal signal being out of phase;
- and
- first circuitry configured to convert the first sinusoidal signal to a first sine voltage for a main winding of the single-phase AC motor;
- and
- second circuitry configured to convert the second sinusoidal signal to a second sine voltage for an auxiliary winding of the single-phase AC motor.
A method of controlling a single-phase AC motor, comprising:
- outputting a first sinusoidal signal and a second sinusoidal signal, the first sinusoidal signal and the second sinusoidal signal being out of phase;
- and
- converting the first sinusoidal signal to a first sine voltage for a main winding of the single-phase AC motor;
- and
- converting the second sinusoidal signal to a second sine voltage for an auxiliary winding of the single-phase AC motor, the first sine voltage and the second sine voltage having a common frequency, an amplitude of the first sine voltage and an amplitude of the second sine voltage being independently adjustable.
Dependencies are inferred from the claim text.