SINGLE-SHUNT CURRENT SENSING FOR MULTI-PHASE MOTOR

摘要

A motor controller for providing a three-phase alternating current (AC) signal to a three-phase motor. The motor controller uses current feedback from a single shunt to monitor or control the three phase AC signal. The motor controller may include a three-phase DC to AC power inverter, a single-shunt current sensor, and a processor. During individual duty cycles when two or more phase signals are too close to each other, the processor may shift one of the phase signals in time so that its leading or trailing edges are a predetermined conflict time away from each other. Then, the processor may sample current from the single-shunt current sensor to determine currents of two of the three phase signals and then calculate current of a remaining one of the three phase signals. Sample times may depend on pulse widths and shifting of the phase signals.

主权项

1. A motor controller for a three-phase motor, the motor controller comprising:
a three-phase DC to AC power inverter configured for providing three separate pulse width modulated (PWM) phase signals for powering the three-phase motor, wherein the phase signals have pulses of varying widths centered at identical points in each duty cycle, the pulses having leading edges and trailing edges; a current sensor coupled in series with the inverter and configured to receive current from the three phase signals simultaneously; and a processor configured for:
controlling pulse-width modulation of the three phase signals of the power inverter;when a pulse width difference between simultaneously occurring pulses of at least two of the phase signals are less than a preselected minimum conflict time, shifting at least one of the phase signals in time such that a difference between leading edges or trailing edges of the pulses are equal to the preselected minimum conflict time;detecting current from the current sensor at sample times a preselected delay time before the leading edge and before the trailing edge of one of the pulses; andshifting at least one of the sample times according to an amount or amounts by which the at least one of the phase signals are shifted.