Research On Sensorless Control Of New DCM

Althought brush DC motors had perfect operation performances; mechanical commutation limited their structure simplification, maintainence and application fields. Modern brushless DC motors (BLDCMs) used electronic commutation instead and solved the preceding problems, and the researches on sensorless control even broaden their application fields. However, as a matter of fact, BLDCMs are Permanent Magnet AC Synchronous Motors, whose congenital weaknesses were obvious:winding inductance limited the output power and the control of winding current was more complicated.Professor WANG-Zongpei, a well-known motor expert of China, proposed the thoughts of New DC Motors (New DCMs in short) with dc-armature winding circuit and electronic commutation. Since 2009, a large number of theoretical and experimental research work on New DCM's Body structure and its drive and control strategies were carried out by our team. The results showed that the New DCM had better operation performances than BLDCMs.HALL components were used for the detection of rotor position for New DCM, with more commutation-units, more HALL components were required, which caused the problems of larger motor size, much more outgoing wires, more complicated body designing and lower operational reliability. Therefore, it was meaningful for this thesis to do research on New DCM's sensorless control.The work of this thesis was mainly reflected in the following aspects:Firstly, the basic structure of New DCM and its operational principle were explained in detail, the mathematical model of New DCM was established, and its operational performance was analyzed briefly.Secondly, with the help of theoretical derivation, simulation analysis and experimental verification, the relationship between New DCM's commutation-unit voltage zero crossing points and its Back-EMF zero crossing points were established. A rotor position detection method, commutation-unit voltage zero-crossing detection method, was proposed and studied, and its detection principle was expounded.Finally, based on MC56F8037 DSP, a sensorless control system of New DCM was established, and commutation-unit voltage detection circuits and zero-crossing algorithm were deeply analyzed. Later, the experiment was successfully carried out, and experimental waveforms were measured and analyzed. It turned out that, the proposed method was feasible and validate.