Patent ID: 8917044

Claim:
A method of driving a multi-phase motor having a plurality of motor windings, the method comprising: generating a motor drive signal with a half bridge circuit coupled to the electric motor, the half bridge circuit comprising: first and second series coupled transistors; a power supply high voltage node for receiving a high power supply voltage; a power supply low voltage node for receiving a low power supply voltage; and an output node at which the motor drive signal is generated; detecting a reverse current passing through at least one of the first or the second transistors, wherein the detecting comprises at least one of: detecting a voltage at the output node that is above the high power supply voltage; or detecting a voltage at the output node that is below the low power supply voltage, wherein the method further comprises; generating a zero current signal indicative of a zero crossing of a current though at least one of the plurality of motor windings in accordance with the detecting the reverse current; generating a position reference signal indicative of a reference position of an angular rotation of the motor; comparing a phase of the zero current signal with a phase of the position reference signal to generate a phase comparison signal and generating a plurality of modulation signals, each having a phase related to a value of the phase comparison signal; and generating a plurality of motor drive signals to the plurality of motor windings in accordance with the plurality of modulation signals, wherein the generating the plurality of modulation signals comprises: providing a look up table in which modulation values are stored corresponding to a shape of at least one of the plurality of modulation signals; generating a first continuous predetermined signal having a smallest value and a largest value and a plurality of values between the smallest and largest values; and adding to the first continuous predetermined signal a value related to the phase comparison signal to generate a second continuous predetermined signal having the smallest value and the largest value and the plurality of values between the smallest and largest values, wherein the smallest and largest values of the second continuous predetermined signal are shifted in time by an adjustment time from the smallest and largest values of the first continuous predetermined signal, wherein the adjustment time is related to the phase comparison signal.