Abstract A direct torque control using new evaluation table of three-level inverter based on duty cycle modulation is proposed for neutral-point clamped three-level inverter-fed permanent magnet synchronous motor drives in order to suppress the steady torque ripples. Firstly, the approach establishes evaluation tables including three vector evaluation tables which evaluate torque and flux of the motor and a compensatory evaluation table which evaluate back electromotive force. The tables are independent to motor parameters in the process of duty modulation adjustment. Secondly, the approach proposes two control schemes for low speed and high speed of the motor. Small vectors and zero vector are employed in the scheme of low speed. Big/medium vectors and small vectors are employed in the scheme of high speed. In this way, the steady of torque is ensured by using the small vectors. Then the vector and duty selection scheme is established based on the cost functions. The proposed algorithm are verified by experiments of a 6kW permanent magnet synchronous motor (PMSM). And the experiment results show that the steady torque ripples are suppressed effectively.
Chen Wei,Zhao Yingying,Zhou Zhanqing. Direct Torque Control Using New Evaluation Table of Three-Level Inverter Based on Duty Cycle Modulation[J]. Transactions of China Electrotechnical Society, 2016, 31(增刊): 128-136.
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