Wide-range speed control of industrial brushless servomotors

Abstract

Considering the performance and cost, the position and wide-range speed control of a servo control system generally adopted an incremental encoder. The so-called M method, based on averaged calculation of encoder pulses, generally results in detection lag during speed estimation. It would be much worse when the interval between the pulses is wider than the sampling time at low motor speeds. As a result, the detection delay time may make the speed control system unstable. In the paper, instead of using a disturbance torque observer, a reference model via proportional-integral-derivative (PID) control is proposed to approach the instantaneous motor speed and improve the low-speed control performance. A digital signal processor (DSP)-based industrial brushless motor drive will present the experimental results, which show the improved resolution and the effectiveness of the proposed method.

Adaptive Low-speed Control of Permanent Magnet Synchronous Motors

“…However, as previously mentioned, the accuracy of the estimated low speed is not enough. This can be improved by the reference model method [17], as shown in Figure 4. …”

“…(34) with a PID compensator shown in Figure 11 [17] is also designed. After gain tuning, the PID gains are given as k po D 0:018, k i o D 0:001, and k d o D 0.…”

“…By placing the current-balanced condition into Eq. (2) and considering Clarke and Park transforms, the equation of the PMSM in the synchronous reference frame fixed to the rotor can be described as [7,11,17] …”

“…The stator voltage equation of a three-phase PMSM can be written as [7,11,17] v abcs D R s i abcs C P abcs ;…”

“…In [17], without using observers, a standard second-order reference model is adopted as the nominal PMSM model. The output of this model is used as feedback, compared with the speed command, and viewed as the instantaneous motor speed.…”