Improved Frequency Division Multiplexing Process for Motor Drives Data Acquisition using Higher Resolver Excitation Frequency

Abstract

Accurate and robust acquisition of angular position and stator currents is critical for developing high-performance three-phase motor drives. Resolver sensor is widely used to measure the motor shaft angular position in harsh conditions. On the other hand, frequency division multiplexing (FDM) is a powerful alternative to send the motor stator current signals and the resolver outputs to the data acquisition system (DAQ) used in three-phase motor drives. In most approaches, the frequency of the resolver excitation voltage is less than the switching frequency of the PWM technique used to control the motor. Hence, the distance between the spectra of the resolver signals and the current signals, which depends on the resolver excitation frequency, is small, increasing the interference of the current signals in the angle estimation (crosstalk). This paper proposes an improved multiplexing approach to reduce the effect of crosstalk in angle estimation. The resolver excitation frequency is 1.5 times the inverter switching frequency so that the resolver outputs are zero when the PWM carrier reaches its valley. Thus, synchronous current sampling can be applied to get the stator current signals, and the effect of crosstalk is reduced in the angle estimation. Simulation results prove that the proposed approach reduces the crosstalk effect in the angle estimation and allows recovering the current signals.