Harmonic Torque Reduction Using Adaptive Sector-Based Torque Feedforward Method for PMSM

In this paper, an adaptive sector-based torque feedforward method which reduces the effect of cogging torque in a permanent magnet synchronous machine is proposed. The proposed method has a table which contains the feedforward torque values directly corresponding to the base-positions equally spacing from 0 to π/3. The table is generated and updated during the drive so that the machine does not have to be pre-investigated, and harmonic torque for various operating points can be reduced. The feedforward torque value for a position is calculated with interpolation from two nearest base-positions. The effectiveness of the proposed method is verified with experiments. Using the proposed method, the speed ripple that could not be coped with a speed controller is reduced by under the half of the original value.