| 摘要 |
PURPOSE:To obtain a trapezoidal wave substantially equivalent to a sine wave by a simple construction, by providing a counter counting output pulses of an oscillator and an integrator taking a rectangular wave out of the output of this counter and converting this rectangular wave into the trapezoidal wave. CONSTITUTION:When an oscillator 1 is made to oscillate at 5MHz, for instance, an output of the highest bit b9 of a 10-bit counter is a symmetric rectangular wave of 5MHz, while the output of a lower bit b8 is a symmetric rectangular wave of 5MHz. When these two rectangular waves are inputted to an exclusive OR circuit 13, the output thereof is a symmetric rectangular wave of 5kHz whose phase is shifted from that of the output of the bit b9. When the output signal of the bit b9 and the output signal of the circuit 13 are amplified 5, 6 and then integrated by integrators 11, 12 respectively, trapezoidal waves are obtained. Viewed as exciting signals to be given to a resolver, these trapezoidal waves operate almost equivalently to cosomegat and sinomegat shifted in phase by 90 deg. from each other. Since these trapezoidal waves are free substantially from a phase error, detection of a position can be performed with high precision when they are used as primary excitation waveforms for a position detector such as the resolver.
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