Wykorzystanie czujników położenia wirnika w obwodzie regulacji prędkości silnika PM BLDC

The basic structure of electric drive control system contains current control circuit (inner loop) and speed control circuit (outer loop). Two criteria are used in setting current and speed controllers: symmetry and absolute value. In application, the goal is to limit the quantity of extra parts used with PM BLDC motors, which are usually small power motors. The simplification of the drive structure may be achieved, for instance, by eliminating tachogenerator and using rotor position sensor for calculating motor rotational speed. The rotor position signals are then converted into signals corresponding to motor's actual speed. The time interval between two rotor characteristic positions is inversely proportional to motor's rotational speed. The measurement delay changes with motor speed and the typical controller settings criteria cannot be applied, since they are based on assuming that time delay is constant. The paper presents a novel method of selecting speed controller with parameters changing with rotational speed. The controller design is shown. Proposed control system structure and method of selecting controller's settings ensure that the drive attains properties similar to those of a drive using speed controller system with symmetry criterion used. The theoretical considerations have been verified with help of computer model and laboratory tests.