Two new digital implementation methods for direct torque control (DTC) of brushless DC motor (BLDCM)

Sections 1 and 2 of the full paper explain in some detail our two new methods; their core consists of: (1) after analyzing the torque characteristics of BLDCM, we obtain the estimated torque equation involving rotor flux linkage and stator current; this estimated torque equation is different from that obtained with the traditional torque equation for DTC of permanent magnetic synchronous motor; (2) after studying the operating principles of the inverter used in BLDCM in the two-phase conducting mode, we obtain two switch tables for the one case of zero vector and the other case of nonzero vector. Section 3 presents two new digital implementation methods A and B for DTC of BLDCM (see the block diagram given in Fig. 3). Subsection 3.2 simulates our two new implementation methods; the simulation results, given in Fig. 4, show preliminarily that our two implementation methods can achieve good instantaneous torque control and reduce some torque ripples. Subsection 3.3 compares the simulation results obtained with our implementation method A with those obtained with the traditional pulse width modulation method; this comparison, presented in Fig. 5, shows preliminarily that our implementation method A has faster torque dynamic response performance and keeps the BLDCM in steadier operation state.