Observer based Speed Control of PMSM using TMS320F2812 DSP
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Date
2012-10
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Addis Ababa University
Abstract
Problems due to mechanical position sensor of Permanent Magnet Synchronous Motor during speed control are alleviated by an observer for estimating instantaneous speed and position of the rotor. This needs a high performance speed and position estimator, i.e. Extended Kalman Filter (EKF), for computing the position and speed of the motor mathematically from current and voltage information using the nonlinear system model. EKF is a set of mathematical equation that provides an efficient computational means to estimate the state of a process, in a way that minimizes the mean of the squared error. It uses tedious mathematical computations recursively which is difficult to use in most digital control systems. EKF algorithm is derived from the input output state space model of the motor. It also considers system and output noise. The mathematical computation can be processed using a Texas Instrument TMS320F2812 DSP with 150MIPS processing speed which is high enough to support it. The system uses Proportional Integral (PI) controller since it is simple and popular in most industrial application. The value of the parameter gains were initially calculated by using pole and zero placements and some tuning was taken place. For the investigation of the problem, both simulation and experimental setups were done. In the simulation, EKF algorithm was written in M-file and embedded on simulation block. To make system control simple, vector control technique was used to control the torque and flux of the motor directly as DC motor. The overall system algorithm is also written in C programming language using code composer studio V3.1 for loading and running into TMS320F2812 DSP to control the motor. Our laboratory motor has no parameter information on it; hence it was difficult to run the motor in closed loop. But to check the functionality of the system Open loop motor running using TMS320F2812 DSP was done.
Keywords: PMSM, Extended Kalman Filter, Vector control, TMS320F2812 DSP, State Observer.
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Keywords
PMSM, Extended Kalman Filter, Vector control, TMS320F2812 DSP, State Observer