Ac motor control system with anticogging circuit

Claim 2

An AC motor control system in which a train of pulses is established at a reference frequency for regulating the frequency of an inverter output voltage utilized to energize an AC motor, and in which an inverter voltage modulating circuit is provided, including the improvement which comprises a first circuit, connected to provide a signal at said reference frequency but differing in phase with respect to the train of pulses at the reference frequency, a second circuit, coupled to said first circuit, for shaping the signal into a square wave and integrating the signal, and a third circuit, coupled between the second circuit and the inverter voltage modulating circuit, for providing an additional phase shift, thus to ensure that the inverter voltage modulation is in the appropriate phase relationship with the train of pulses at the reference frequency.

Claim 3

An AC motor control system as claimed in claim 1, in which the inverter voltage modulating circuit includes a volts/Hertz regulator.

Claim 4

An AC motor control system as claimed in claim 2, and further comprising a claim circuit, coupled between said third circuit and the volts/Hertz regulator, to protect the system during removal of the train of pulses as the direction of motor rotation is reversed.

Claim 5

An AC motor control system as claimed in claim 1 in which each of said second and third circuits comprises a square wave shaper circuit, and an operational amplifier connected as an integrator circuit and coupled to the output side of the square wave shaper circuit.

Claim 6

An AC motor control system as claimed in claim 4, and further comprising a feedback circuit, coupled between the output side of the third circuit and an intermediate portion of the second circuit, to assist in minimizing the DC offset of the operational amplifier in the second circuit.

Claim 7

An AC motor control system as claimed in claim 5, in which said feedback circuit includes a square wave shaper circuit.

Claim 8

An AC motor control system as claimed in claim 1, and further comprising an inverter logic stage connected to receive the train of pulses at the reference frequency and to regulate the frequency of the inverter output voltage in accordance with the train of pulses, means for providing an additional train of pulses at a frequency twice the reference frequency, and a divide-by-two stage in said first circuit, having an input circuit connected to receive the additional train of pulses at twice the reference frequency, a first output circuit for passing a first train of pulses at said reference frequency toward the inverter logic stage, and a second output circuit connected to provide a second train of pulses at said reference frequency, but displaced in phase relative to the first train of pulses, to the input side of the second circuit.

Claim 9

An AC motor control system in which the output voltage from an inverter energizes an AC motor, an inverter logic stage is connected to regulate the frequency of the inverter output voltage, and a volts/Hertz regulator is connected to modulate the amplitude of the inverter output voltage, characterized by a divide-by-two circuit for receiving an input train of timing pulses and providing first and second trains of output pulses displaced in phase relatIve to each other, means, including a pulse amplifier circuit, for passing the first train of pulses from the divide-by-two circuit to the inverter logic stage, means, including a second circuit comprising a square wave shaper and an operational amplifier, for receiving the second train of pulses and producing an intermediate signal, a third circuit, comprising a second square wave shaper and a second operational amplifier, connected to add another phase shift into the intermediate signal, a clamp circuit connected to pass the intermediate signal from the second operational amplifier to the volts/Hertz regulator, and a feedback circuit, including a third square wave shaper circuit, coupled between the output side of the second operational amplifier and the input side of the first operational amplifier.

Claim 10

An AC motor control system in which the output voltage from an inverter energizes an AC motor, an inverter logic stage is connected to regulate the frequency of the inverter output voltage, and a volts/Hertz regulator is connected to modulate the amplitude of the inverter output voltage, characterized by a divide-by-two circuit for receiving an input train of timing pulses and providing first and second trains of output pulses displaced in phase relatIve to each other, means, including a pulse amplifier circuit, for passing the first train of pulses from the divide-by-two circuit to the inverter logic stage, means, including a second circuit comprising a square wave shaper and an operational amplifier, for receiving the second train of pulses and producing an intermediate signal, a third circuit, comprising a second square wave shaper and a second operational amplifier, connected to add another phase shift into the intermediate signal, a clamp circuit connected to pass the intermediate signal from the second operational amplifier to the volts/Hertz regulator, and a feedback circuit, including a third square wave shaper circuit, coupled between the output side of the second operational amplifier and the input side of the first operational amplifier.