A full-range-360° resolver-to-DC converter

Abstract

In this paper, a triangular-to-sawtooth waveform converter and a control logic circuit have been described. Using two designed circuits connected with OTA-based sine-to-triangular wave converter and demodulator, a resolver-to-DC converter is proposed. The converter linearly produces output signal proportional to the shaft angle in full range of 360°. Experimental results verifying the performances of the proposed converter circuit agree well with the theoretical prediction.Keywords: Resolver converter, inverse-sine function circuit, arcsine function circuit and sine-to-triangular converter.order to obtain the ease of design, we let the amplitudes of the voltage V s and V c are equal to one, that can be expressed asThe OTA-based sine-to-triangular converter functions as the inverse-sine function circuit with dynamic range of ± n/2, this circuit is connected to convert the voltage V s into the current signal la, which can be written as where Go is a constant gain of sine-to-triangular converter [7]. From Eq. (3) for ±2n-range the current signal 1 0 is a piecewise-linear function of the shaft angle B. To improve results of the resolver converter, the current 1 0 is fed to the triangular-to-sawtooth waveform converter. Considering the block of triangular-tosawtooth waveform converter, the scheme composes operational amplifiers (Op Amps) A 3-A6 , analog switches SWI-SW3, and DC-voltage source V 3 connected with nine resistors. The operation of this scheme can be explained as follows. Op Amp A 4 connected with the resistors R1 and R 2 transfers the current signal 1 0 into the signal voltage Va and also functions as a inverting-amplifier for the voltage Va and V 2 , which can be stated as (3) (2); 0 <181 <nj2 1 0 == Go n -8 ;nj2 <181~3nj2 8-2n ;3nj2 <181~2nWhere Bis a resolver shaft angle. CIRCUIT DESCRIPTION2.1 Basic Principle Fig. 1 shows the circuit diagram of the proposed resolver-to-DC converter formed by four sub-circuits, which are the demodulator, the OTA-based sine-to-triangular waveform converter, the triangular-tosawtooth waveform converter, and the control logic circuit. The proposed technique uses the traditional principle for stimulating the rotor winding of the resolver. The sinusoidal voltage signal Vex is applied to the rotor winding. The output signals of two stator windings are fed to the demodulator [6]. The voltages V s and V c are the output signals of the demodulator. In Resolver is the shaft angle transducer especially suitable to determine the absolute position of the motor shaft over one revolution. Furthermore, the speed and the encoder simulation for the position control of the servo-drives can be derived from resolver signals. The basic idea of the resolver converter is to convert the resolver signals, which are the trigonometric functions, into linear signals. In the past, the converter methods based on phase-locked loop technique [1-2] or look-up table technique [3]. Alternatively, the new design of resolver-to-DC converter without a processor and/or look-up table technique has been descri...

Design of a precise and robust linearized converter for optical encoders using a ratiometric technique

“…Thus, within a signal period, the phase angle and the displacement can be determined linearly from the magnitude of θ V ( ) OLR using a similar technique to that used in the literature [32,33] as…”