Gm Global Technolgoy Operations, Inc.

Delco Electronics Corporation

Gordon D Cheever, Jr

Kevin Michael Deasy

Daniel E Utley

A multi-processor AC motor control system having a timer processor which generates multiple synchronized PWM waveforms while minimizing software latency effects. The timer processor generates a 50% PWM duty cycle sync signal at the PWM frequency, creating a logic level transition (leading edge) in each PWM period. At each such transition, the timer processor interrupts the host processor for the purpose of updating a multi-byte timer data register with PWM on-time data stored in nonvolatile memory as a function of machine position and requested current. A separate timer channel is provided for each PWM waveform to be generated, and the timer processor sets off-to-on and on-to-off transitions of each waveform in accordance with the updated PWM on-time data such that respective off-to-on and on-to-off transitions in each waveform are centered about the leading edges of the sync signal. If the on-time is 0% or 100%, the timer processor overrides the normal instruction set and forces the logic state of the waveforms to a full-off or full-on logic state.

Micro-controller based PWM waveform generation for a multiple phase AC

An improved digital PWM closed-loop current control for a multiple phase winding AC machine which requires only a single sensor for monitoring the current in one of the phase windings of the machine. The PWM on-time values for the various phase windings of the machine are stored in a single look-up table as a function of stator position and requested current amplitude, and the on-times used to schedule phase winding energization are periodically updated using a two-part look-up procedure. Initially, the stored on-time value for a single phase winding is retrieved from the table as a function of stator position and the requested current amplitude. The retrieved value is then compared with a measure of the actual current in the respective phase winding to form an error signal, which is used to adjust the requested current amplitude. The requested current amplitude, as adjusted, is then used, along with the stator position, as a table look-up parameter to retrieve PWM on-times for all three phase windings, thereby automatically adjusting multiple phase winding currents in a balanced fashion.

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Kokomo, IN, United States of America

Gordon D Cheever, Jr