초록 ▼

In a plural phase electric motor, a control system provides a variable commutation delay interval between commutations from state to state, during which delay interval all phases are unenergized, to minimize current spikes upon commutation. The duration of the delay interval is varied according to a

In a plural phase electric motor, a control system provides a variable commutation delay interval between commutations from state to state, during which delay interval all phases are unenergized, to minimize current spikes upon commutation. The duration of the delay interval is varied according to a given motor operating parameter during operation of the motor to optimize the delay interval for different operating conditions, to provide maximum delay when needed to eliminate current spikes, and to provide minimum delay when unneeded, to in turn provide maximum energization current to the phases. In one embodiment, motor speed is sensed, and the duration of the delay interval is varied in response thereto by shortening the delay interval with increasing motor speed. In another embodiment, DC bus current is sensed, and the duration of the delay interval is varied in response thereto by preventing termination of the delay interval until the level of DC bus current drops below a given value.

대표청구항 ▼

A method of controlling an electric motor having three phases, A, B, and C, comprising energizing the phases with energization current in a cyclic sequence comprising a plurality of states, 1, 2, 3, and so on, wherein during each state, two of the phases are energized and the third phase is unenergi

A method of controlling an electric motor having three phases, A, B, and C, comprising energizing the phases with energization current in a cyclic sequence comprising a plurality of states, 1, 2, 3, and so on, wherein during each state, two of the phases are energized and the third phase is unenergized, such that upon commutation from the state 1 to the state 2, current through the phase B is equal to a sum of energization current through the phase C plus inductive current through the phase A due to energization thereof in the state 1, said sum of said currents causing potentially destructive current spikes upon said commutation to the state 2, said method comprising providing a variable commutation delay interval between commutations from state to state during which delay interval all phases are unenergized to minimize said current spikes upon commutation, and varying the duration of said delay interval according to a given motor operating parameter during operation of said motor to optimize said delay for different operating conditions, to provide maximum delay when needed to eliminate said current spikes, and to provide minimum delay when unneeded, to in turn provide maximum energization current to said phases.