A Direct Torque Control Scheme for BLDC Motor Drives with Open-end Windings

This article proposes a five-level torque hysteresis based direct torque control (DTC) scheme for a dual inverter fed 3-phase BLDC motor with open-end stator windings. The five-level torque controller facilitates finer control of the torque compared to conventional three-level torque controller based DTC scheme for BLDC motors. The proposed scheme is based on the voltage space vector structure of the BLDC drive developed by combining the voltage space vectors of the two inverters operated in 120
⁰
conduction mode. This space vector structure contains some ‘uncertain space vectors’ and is different from that of three phase open-end winding drives. The ‘uncertain space vectors’ whose directions are not known in advance are not used for implementing the control scheme. Appropriate null vectors and active vectors are used for torque control. Numerical simulation is performed in Matlab-Simulink platform and experimental verification of the proposed DTC scheme is conducted on a laboratory prototype using TMS320F28377S digital signal processor for implementing control algorithm.