Harmonic Current Injection Method for Torque Ripple Suppression over Wide Speed Range Considering Magnetic Saturation in PMSMs

We propose a flux-based harmonic current injection method that accounts for magnetic saturation to suppress torque ripple in permanent magnet synchronous motors feedforwardly. The key feature of the proposed method is converting a harmonic-current command into a flux command by pre-acquired nonlinear flux information and converting the flux command into voltage commands through an approximate equation. Numerical simulations demonstrate that this method reduces 12thorder torque ripple by over 70% within a wide frequency range. Experimental results indicate that the amplitude and phase errors of the injected harmonic flux can be held to as low as 0.2% and 2.9°, respectively, even without additional feedback control for harmonics.