Analysis about the Application of Frequency-Domain Multiplexing in Data Acquisition for Vector Control

Frequency-domain multiplexing (FDM) allows simplifying the acquisition hardware applied in the vector control of three-phase motors, when a resolver sensor is used to get the angular position. Conventionally, an analog switch is used together with an analog-to-digital converter to digitize the signals. This approach is based on time-domain multiplexing (TDM). However, the application of FDM in data acquisition has many advantages respect to the conventional approach based on TDM. Signals from the stator current sensors and from the resolver can be multiplexed in frequency by combining these signals through analog adders. Nevertheless, the demultiplexing process in order to recover the original data is still a open question. This paper does an analysis of the demultiplexed signals, in order to give more theoretical background for the development of improved data acquisition systems based on FDM. Simulation results show that using a high-pass filter improves the demultiplexing of the resolver outputs.