Application of Frequency Division Multiplexing in the Speed Control of PMSM

Resolver is a sensor used to measure the motor shaft angle in harsh conditions. This sensor produces two amplitude-modulation voltages. On the other hand, vector control of three-phase motors requires sensing at least two stator currents. Hence, the data acquisition system (DAQ) of a motor drive must digitize at least four analog signals when a resolver is applied in vector control. Most DAQs apply time-division multiplexing (TDM) to simplify the signal digitization. However, frequency-division multiplexing (FDM) was proposed to simplify the acquisition of the stator currents of a three-phase motor drives when a resolver is used as angular position sensor. FDM allows a faster sampling of the signals than TDM. This multiplexing approach was improved by using a higher resolver excitation signal. This paper explores the application of FDM in vector control of a permanent magnet synchronous motor and analyze the effect of this multiplexing approach in the motor speed control.