High-accuracy resolver-to-linear signal converter.

A high-accuracy resolver-to-linear signal converter for the measurement of angular displacement is proposed in this paper. The proposed converter comprises two sections: a demodulator and linear shaper. In the first section, the demodulator makes use of the sample-and-hold circuit (SHC) to sample the peak amplitude of the resolver signal. The control signal of the SHC is provided from the resolver signals instead of the excitation signal used in traditional approaches. The proposed demodulator requires no analogue multiplier and low-pass filter. Therefore, the fast response time of the proposed demodulator is achieved. In the second section, the linear shaper consists of the inverse-sine function scheme together with a switched-gain amplifier to produce the linear signal proportional to the shaft angle. The hyperbolic tangent characteristic of the operational transconductance amplifier is utilised to realise the inverse-sine function scheme. The proposed technique requires one phase of the resolver signal to obtain the linear signal. Therefore, the position error caused by amplitude imbalance between the two resolver signals is avoided. The performances of the proposed converter are discussed in detail and demonstrated by an experimental implementation using commercial devices. The experimental results show that the maximum relative error and response time for the excitation frequency of 3 kHz are measured as 0.06% and 0.11 ms, respectively. [ABSTRACT FROM AUTHOR]