A simple speed observer for digitally controlled motor drives at low speeds

A simple speed observer has been studied to improve the transient behavior of digitally-controlled DC motor drives at very low speeds. The motor speed is estimated simply using the machine electrical equation. To correct the estimation error two methods are discussed. The simulation results validated by experiments show that the gain correction is more powerful than an additive correction. Using this method the estimated speed is always acceptable because the observer parameters converge to the ideal values. This type of speed observer is also simpler to implement than a state observer because of lesser computation. It is thus well suited for microprocessor-based control systems.<>