Online Inverter Nonlinearity Compensation Method Based on Current Injection

The non-linearity of the voltage source inverter (VSI) causes an error between the output voltage and the reference voltage, therefore introduces phase current harmonic interference. This paper proposes a method for online compensation of inverter nonlinear errors. The effect of parasitic capacitance is modeled by injecting increasing or decreasing current. The voltage drop of the semiconductor diode is obtained through the datasheet. Two non-linear functions are used to compensate for the above non-linear factors, the current loop control period and dead time are confirmed during the auto-tuning process. The method proposed in this paper does not require any additional filters that cause phase delay and reduced amplitude. The experimental results are obtained by a commercial permanent magnet synchronous motor (PMSM) drive platform based on a DSP controller. The experiments verify the proposed online compensation method.