Abstract: An apparatus includes a switch module that selectively turns on a switch to connect an input power conductor connected to a voltage source to a motor in a sequence. The switch for each phase is turned on for a portion of a cycle of a fundamental frequency of the voltage source. A source phase module determines a phase of the AC voltage source, a back-EMF phase module determines a phase of a back-EMF of the motor, and a torque module determines when a phase difference between the phase of the AC voltage source and the phase of the back-EMF is within a phase range indicative of a positive motor torque. A pulse module enables the switches in response to the phase difference having a phase within the phase range and disables the switches in response to the phase difference having a phase not in the phase range.

Abstract: An apparatus for a quasi variable frequency motor controller is includes a DFC module that applies a first frequency to a motor as part of a discrete frequency control (“DFC”) method for motor starting. The first frequency includes a discrete frequency in a plurality of discrete frequencies of the DFC method and each discrete frequency includes a frequency lower than a fundamental frequency of an alternating current (“AC”) voltage source providing power to the motor. The apparatus includes a torque module that determines when motor torque generated by the motor reaches a negative torque threshold and a next frequency module that applies a second frequency to the motor in response to the torque module determining that the motor torque has reached the negative torque threshold. The second frequency is a next frequency in the DFC method.

Abstract: An apparatus includes a switch module that selectively turns on a switch to connect an input power conductor connected to a voltage source to a motor in a sequence. The switch for each phase is turned on for a portion of a cycle of a fundamental frequency of the voltage source. A source phase module determines a phase of the AC voltage source, a back-EMF phase module determines a phase of a back-EMF of the motor, and a torque module determines when a phase difference between the phase of the AC voltage source and the phase of the back-EMF is within a phase range indicative of a positive motor torque. A pulse module enables the switches in response to the phase difference having a phase within the phase range and disables the switches in response to the phase difference having a phase not in the phase range.

Abstract: An apparatus for a quasi variable frequency motor controller is includes a DFC module that applies a first frequency to a motor as part of a discrete frequency control (“DFC”) method for motor starting. The first frequency includes a discrete frequency in a plurality of discrete frequencies of the DFC method and each discrete frequency includes a frequency lower than a fundamental frequency of an alternating current (“AC”) voltage source providing power to the motor. The apparatus includes a torque module that determines when motor torque generated by the motor reaches a negative torque threshold and a next frequency module that applies a second frequency to the motor in response to the torque module determining that the motor torque has reached the negative torque threshold. The second frequency is a next frequency in the DFC method.