| 摘要 |
An apparatus and method for compensating output signals of a magnetic encoder are disclosed. The apparatus includes a pre-calibration unit, an advanced phase detector, a loop filter, a voltage controlled oscillator (VCO), and a pulse generator. The pre-calibration unit obtains two phase-compensated waveforms through trigonometric function operations, and adjusts the amplitudes of the two phase-compensated waveforms to the same value, thereby generating input sine and cosine waves. The advanced phase detector generates an error output signal through trigonometric function operations. The loop filter sets the filter transfer function of an active lead-lag filter, and then filters the error output signal. The VCO generates a compensated signal. The pulse generator outputs a phase index, and generates two output pulses having a phase difference of 90 degrees in accordance with a pulse generation rule of a look-up table. |
| 主权项 |
1. An apparatus for compensating output signals of a magnetic encoder, comprising:
a pre-calibration unit configured to obtain two phase-compensated waveforms having an identical phase, through trigonometric function operations of normalized waveforms of digitally converted sine and cosine waves, which are converted from ME (magnetic encoder) output sine and cosine waves output from a magnetic encoder, and configured to adjust amplitudes of the two phase-compensated waveforms to be equal, thereby generating input sine and cosine waves having an identical phase and an identical amplitude; an advanced phase detector configured to generate an error output signal through trigonometric function operations of the input sine wave, the input cosine wave, and a compensated sine wave and a compensated cosine wave having an estimated phase, so that the error output signal has a sine term of a phase error, between a phase, of the input sine wave or the input cosine wave, and the estimated phase, of the compensated sine wave or the compensated cosine wave, as a multiplying term; a loop filter configured to set a filter transfer function of an active lead-lag filter based on a natural frequency and a damping factor determined based on the error output signal and overshoot, and to filter the error output signal using the active lead-lag filter; a voltage controlled oscillator (VCO) configured to generate a compensated signal including the compensated sine and cosine waves having the estimated phase based on a signal obtained by passing the filtered error output signal through an integrator having a predetermined gain; and a pulse generator configured to output a phase index, corresponding to a current phase of the compensated sine and cosine waves, selected among M fractionized phase indices obtained from fractionizing a full range of phase within a single period of the compensated sine and cosine waves by M, and configured to generate two output pulses having a phase difference of 90 degrees in accordance with a pulse generation rule found in a look-up table, based on the phase index of the current phases, the look-up table storing pairs of size values of frequency-multiplied sin and cosine waves assigned to each of the phase indices. |
