Energies, Vol. 11, Pages 2729: A Composite Vectors Modulation Strategy for PMSM DTC Systems (Energies)

The operation performance of permanent magnet synchronous motors (PMSMs) driven by direct torque control (DTC) are affected by torque error compensation and flux error compensation in each control period. The error compensational effects provided by different vectors under different control strategies are analyzed in this paper. The precondition of accurate error compensation is applied to the proposed novel composite vectors modulation strategy (CVM) for a PMSM DTC system. In CVM-DTC, the operating conditions of PMSM are divided into three cases according to the relationships between the errors and the actual error compensations, including steady-state case, dynamic-state case, and transient-state case. In order to establish the novel CVM-DTC strategy smoothly, the effect factors are introduced and used to represent the error compensational effects, which are obtained through the proposed effect factors’ controller. The analysis of error compensational effects provided by single active vector and synthetic voltage vector are described in detail while the PMSM is operated in different operation conditions. Finally, the effectiveness of the novel CVM-DTC strategy is verified through the experimental results in a 100-W PMSM drive system.