New Acoustic Noise Reduction Method for Signal-Injection-Based IPMSM Sensorless Drive

Many signal-injection-based sensorless methods have been developed to drive the interior permanent magnet synchronous motor without a position sensor at low speed. By these methods, rotor position can be estimated by measuring the output current ripple of inverter caused by the injected signal. However, this ripple is able to generate the undesirable acoustic noise, which decreases the usefulness and practicality of method while preventing the increase of signal-to-noise ratio. This article proposes the new acoustic noise reduction method by injecting signals to both d- and q-axes, respectively, to reduce torque ripple components for position estimation. In particular, the frequency of injected signals is matched with the pulsewidth modulation switching frequency to maximize the bandwidth for position estimation. By the proposed method, the sensorless drive with high performance can be achieved while suppressing the acoustic noise caused by injecting signals. The compensation for signal distortion is first studied by simulation with the analysis of nonlinear properties of high-frequency signal. Then, the practical effectiveness of the proposed method is verified by experimental results.