Harmonic currents suppression in direct torque control of dual three-phase permanent magnet synchronous motor

There are a great quantity of 6 k±1 (k=1, 3, 5, …) harmonic currents in the z₁-z₂ sub-plane when the basic voltage vectors are adopted in switching-table-based direct torque control (DTC) for dual-three phase permanent magnet synchronous motor (PMSM) drives. By introducing the principle of pulse width modulation, the voltage vector was modified, and the modified intermediate vector was centralized for simplifying the hardware implementation. Both simulation and experimental results demonstrate that the harmonic currents in the z₁-z₂ sub-plane can be suppressed significantly when the modified intermediate vectors are adopted for DTC, so the system losses are reduced. Furthermore, the static and dynamic performances of the control system are not affected.