Full Order Discrete-Time Modeling for Accurate and Speed-Independent Pulsating Voltage Injection Self-Sensing

A method to accurately estimate the current considering the effects of resistance, salient inductance, and stationary frame latched voltage is developed. This method can be applied to applications which require highly accurate position, speed, current, or torque control using self-sensing and where simplifying assumptions in the model lead to unacceptable errors. This paper considers the effects of non-ideal modeling on the current response to a high frequency pulsating voltage injected into the estimated synchronous frame specifically for use with self-sensing control algorithms for the estimation of rotor position. In this application, the q-axis current due to non-ideal effects, such as resistance and the stationary frame voltage latch, leads to in errors in the rotor position estimate. To overcome this, a demodulation method is developed which accounts for these effects and removes their impact on the rotor position estimate. The accuracy of both the resulting current observer to estimate current, and the demodulation process to estimate position are evaluated.