ROTATIONAL ANGLE DETECTOR

PURPOSE:To detect an angle of rotation at low cost with high accuracy without using any expensive filter by supplying two stator coils with waveforms which are 90 deg. out of phase with each other and expressed by a specific equation. CONSTITUTION:The timing generation part 2 of the arithmetic device 1 consisting of a CPU, etc., outputs the rectangular wave signals which are 90 deg. out of phase with each other and expressed by the equation f{(T/2+t=-f(t)} (t: time, T: period) and they are inputted to the stators A and B of a resolver 5 through driving circuits 3 and 4 respectively. A signal (c) led out of the rotor of the resolver 5 through an output circuit 6 is sampled by an A/D converter 7 at a 1/8 period and converted into a digital signal (d), which is inputted to the arithmetic device 1 to calculate the angle theta according to the output signal (d) of the A/D converter 7. Consequently, the angle of rotation can be detected at low cost with high accuracy without using any expensive filter.