Incremental servo motor encoder zeroing method！

In this discussion, the incremental encoder output signal for the square wave signal, can be divided into commutation signal with the incremental encoder and incremental incremental encoder, the general incremental encoder with two Phase square wave pulse output signals A and B, and the zero signal Z; commutation signal with the incremental encoder in addition to the output signal with ABZ, but also have mutual difference of 120 degrees of electronic commutation signal UVW, UVW each Of the number of cycles per revolution corresponds to the number of poles of the motor rotor. The alignment between the phase of the UVW electronic commutation signal of the incremental encoder with the commutation signal and the phase of the rotor pole, or of the phase angle of the electrical phase, is as follows:
1. Using a DC power supply to the motor through the UV winding is less than the rated current of the DC, U into, V out, the motor shaft is directed to an equilibrium position;
2. Observe the U-phase signal and Z-signal of the encoder with an oscilloscope;
3. Adjust the relative position of the encoder shaft and the motor shaft;
4. While adjusting, watch the encoder U-phase signal edge, and Z signal, until the Z signal is stable at a high level (in this default Z signal is normally low), lock the encoder and the motor relative Positional relationship;
5. After the motor shaft is rotated back and forth, the Z-signal can be stabilized at the high level every time the motor shaft is free to return to the equilibrium position, then the alignment is effective.
After removing the DC power supply, verify the following:
1. Observe the U-phase signal of the encoder and the UV-ray back EMF waveform of the motor with an oscilloscope.
2. Rotate the motor shaft, the encoder's U-phase signal rising edge and motor UV back EMF waveform from low to high zero-crossing coincidence, the encoder Z signal also appears in the zero-crossing point.
The above verification method can also be used as an alignment method.
It should be noted that, at this time, the phase zero of the U-phase signal of the incremental encoder is aligned with the phase zero point of the motor UV back EMF, and the difference between the U-back EMF of the motor and the UV back EMF is 30 degrees. After this alignment, the phase zero point of the U phase signal of the incremental encoder is aligned with the -30 degree phase point of the opposite potential of the motor U, and the phase angle of the motor electrical phase coincides with the phase of the U opposite potential waveform, so the incremental coding The phase zero of the U phase signal is aligned with the -30 point of the motor electrical angle phase.
Some servo companies are accustomed to the encoder U-phase signal zero point and the electrical point of electrical direct alignment, in order to achieve this purpose, you can:
1. Connect three resistors with equal resistance to star type, then connect three star-connected resistors to the UVW three-phase winding leads of the motor respectively;
2. Oscilloscope to observe the motor U-phase input and star resistance of the midpoint, you can approximate the motor U-back EMF waveform;
3. Depending on the ease of operation, adjust the relative position of the encoder shaft and the motor shaft, or the relative position of the encoder housing and the motor housing;
4. While adjusting, watch the intersection of U and the intersection of signal and rising edge of the intersection of U and signal of the intersection of encoder and U of the intersection of U and electric potential wave of the intersection of electric potential and low from the intersection of zero and high, watch the intersection of rising edge and zero crossing finally, lock the intersection of encoder and relative position, .
Since the conventional incremental encoders do not have UVW phase information and the Z signal only reflects one point within a circle, there is no direct phase alignment potential and is therefore not a topic of discussion.

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