Single Current Sensor-Based Current Control Method for IPMSM Under Six-Step Operation

Abstract

This article presents a current control method for six-step operation of an interior permanent magnet synchronous machines using only a single current sensor. Although various control strategies have been investigated for six-step operation, inverter systems with a single current sensor remain constrained, as only one phase current can be sampled per step. This limitation reduces the sampling frequency, which in turn results in degraded control bandwidth. In addition, current control implemented with a fixed sampling period may induce low-order harmonic components. To address these challenges, a novel synchronous sampling method is proposed to suppress low-order harmonics, and a current prediction method is introduced for reconstructing three-phase currents from a single measured dc-link current based on a variable sampling period. By increasing the number of sampling points through current prediction, both dynamic torque response and control bandwidth can be improved, achieving performance comparable to inverter systems with multiple current sensors. The effectiveness of the proposed methods is validated through experimental results.