Position Sensorless Control of CHB Converter Fed Three-Phase PMSM Drives Using Collaborative High-Frequency Square-Wave Voltage Injection

In this article, the position sensorless control with high-frequency (HF) square-wave voltage injection is investigated for cascaded H-bridge (CHB) converter fed three-phase permanent-magnet synchronous motor (PMSM) drives. A collaborative HF signal injection method is proposed for CHB topology to decouple frequencies of the injected HF signals and the carrier. In each phase of the CHB converter, a single H-bridge is configured to inject the square-wave voltage while the others are configured for the modulation of reference voltages. Therefore, the frequency of the orthogonal square wave can be equal to or higher than that of the carrier and thus the position estimation performance is improved. Moreover, a cumulative signal processing method is proposed to eliminate the influence of square wave harmonics. Simulation verification has been conducted to validate the effectiveness of the proposed sensorless control scheme.