A SENSORLESS BRUSHLESS DC MOTOR PHASE ADVANCE ACTUATOR BASED ON THE TMS320C50

This application report describes the development of a sensorless brushless DC motor phase advance actuator system based on the Texas Instruments (TI(TM)) TMS320C50 digital signal processor (DSP) and TMS320C50 evaluation module (EVM). Results show that applying a direct digital control methodology to the problem of controlled phase advance in a brushless DC machine substantially increases the effective speed range and facilitates a constant power profile. In addition, a further application to the control of torque ripple during controller saturation is demonstrated.

Phase advance techniques provide field-weakening operation for brushless machines and have been the subject of significant research over recent years. Unlike previously documented methods that typically require a position encoder, the technique described in this paper renders such position sensing equipment redundant, reducing unit costs and increasing system reliability.

The ability to perform significant mathematical computations over relatively small sample periods (typically 50ms) allows precise control of electrical machine phase currents. A fast DSP hardware platform is thus paramount for investigating sensorless phase advance techniques. A desired system requirement is a fast data exchange capability with the external environment encompassing both integrated speed control, current, and phase advance actuation with diagnostic and supervisory procedures.

This document was part of the first European DSP Education and Research Conference that took place September 26 and 27, 1996 in Paris. For information on how TI encourages students from around the world to find innovative ways to use DSPs, see TI's World Wide Web site at www.ti.com.

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(c) Copyright 1998 Texas Instruments Incorporated. All rights reserved.
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