Microprocessor-based Speed Control Research Articles

Microprocessor-based DC motor drive with spillover field weakening

A microprocessor-based speed control scheme for a separately excited DC motor fed from a DC source, which incorporates both armature-voltage control and spillover field weakening to provide smooth and precise control from standstill to speeds well above the base value, is described. Armature-current limitation during transient operation is achieved using an interventionist system external to the microprocessor controller, thereby simplifying considerably the overall system design. Experimental results obtained from a prototype 5 kW drive are presented to illustrate the excellent dynamic behavior of the scheme. >

Software Pulsewidth Modulation for μP Control of AC Drives

The on-line pulsewidth modulation (PWM) of a voltage source inverter for converter-fed ac drives is presented. The modulation is realized by software, thus allowing a direct interface between the microprocessor-based speed control and the on-off commands for the inverter. An efficient modulation technique is achieved by asynchronous switching of the inverter phases; a current control loop provides fast feedback, so that a fast step response of the stator currents can be obtained. All control functions, including field-oriented speed control of an induction motor, are performed by a 16-bit microprocessor. Experimental results obtained with a 22-kW induction motor prove that the proposed scheme provides a very good performance of the drive from standstill up to the field weakening range.

Microprocessor-Based Speed Control System for High-Accuracy Drives

A digital speed control system for a dc motor with a pulse tachogenerator for speed sensing is described. A microprocessor is used for fast speed measurement with a response time constant of the order of 8 ms and a resolution of 0.0125 percent of the top speed. This has become possible because of the principle of obtaining the latest speed value based on the previous speed value. This paper describes the principle of speed measurement and control, the flowchart, and the experimental results. A closed-loop speed holding accuracy of ±0.025 percent of the top speed is obtained.