Incremental encoder phase alignment - Database & Sql Blog Articles

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The output signal of the incremental encoder is a square wave signal, which can be divided into an incremental encoder with a commutation signal and a conventional incremental encoder. The ordinary incremental encoder has a two-phase orthogonal square wave. Pulse output signals A and B, and zero-bit signal Z; Incremental encoder with commutation signal, in addition to the ABZ output signal, also has the number of revolutions per revolution of the electronic commutation signal with 120 degrees difference from each other and the motor rotor The number of magnetic poles is the same. The alignment of the phase of the UVW electronic commutation signal with the incremental encoder with the commutation signal and the phase of the rotor pole, or the phase of the electrical angle are as follows:
1. Use a DC power supply to pass the DC winding of the motor to a DC current less than the rated current, U in, V out, to orient the motor shaft to an equilibrium position;
2. Observe the U phase signal and Z signal of the encoder with an oscilloscope; adjust the relative position of the encoder shaft and the motor shaft, or the relative position of the encoder housing and the motor housing, according to the convenience of operation;
3. While adjusting, observe the U-phase signal edge of the encoder and the Z signal until the Z signal is stable at a high level (in this case, the normal state of the Z signal is low), and lock the encoder to the motor. Positional relationship;
Reverse the motor shaft back and forth. After releasing the hand, if the motor shaft is free to return to the equilibrium position each time, the Z signal can be stabilized at a high level, and the alignment is effective.
After removing the DC power supply, verify as follows:
Observe the U phase signal of the encoder and the UV back EMF waveform of the motor with an oscilloscope;
When the motor shaft is rotated, the rising edge of the U-phase signal of the encoder coincides with the zero-crossing point of the UV line back EMF waveform of the motor, and the Z signal of the encoder also appears at this 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 point of the U-phase signal of the incremental encoder is aligned with the phase zero point of the motor UV back-EM potential. Since the U-electrode potential of the motor is different from the UV-line back-EM potential by 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 angle is the same as the phase of the potential waveform of the U opposite, so the incremental coding is performed at this time. The phase zero of the U-phase signal of the device is aligned with the -30 degree point of the electrical phase angle of the motor.
^ Some servo companies are accustomed to directly aligning the zero point of the encoder's U-phase signal with the zero point of the motor's electrical angle. To achieve this, you can:
1. Connect three stars with the same resistance to form a star, and then connect the three resistors connected to the star to the UVW three-phase winding leads of the motor;
2. Observing the midpoint of the U-phase input of the motor and the star-shaped resistor with an oscilloscope, the approximate U-potential waveform of the motor can be approximated;
Adjusting the relative position of the encoder shaft and the motor shaft, or the relative position of the encoder housing and the motor housing, depending on the ease of operation;
3. While adjusting, observe the rising edge of the U-phase signal of the encoder and the zero-crossing point of the potential waveform of the motor U from low to high, and finally make the rising edge and the zero-crossing point coincide, lock the relative position relationship between the encoder and the motor, and complete the alignment. .
Since the conventional incremental encoder does not have UVW phase information, and the Z signal can only reflect one point within one circle, and does not have direct phase alignment potential, it is not a topic of discussion.
Phase Alignment of Absolute Encoders The phase alignment of absolute encoders is not much different for single and multiple turns. In fact, the phase of the detected phase of the encoder and the electrical angle of the motor are aligned within one turn. Early absolute encoders gave the highest level of the single-turn phase as a separate pin. With this level of 0 and 1 flipping, the phase alignment of the encoder and motor can also be achieved as follows:
Use a DC power supply to pass the UV winding of the motor to a DC current less than the rated current, U in, V out, to orient the motor shaft to an equilibrium position;
4. Observe the highest count bit level signal of the Absolute Encoder with an oscilloscope;
Depending on the ease of operation, adjust the relative position of the encoder shaft and the motor shaft, or adjust the relative position of the encoder housing and the motor housing while observing the transition edge of the highest count bit signal until the jump edge appears accurately in the motor. The relative positional relationship between the encoder and the motor is locked at the directional balance position of the shaft;
5. Reverse the motor shaft back and forth. After the hand is released, if the motor shaft is free to return to the equilibrium position each time, the jump edge can be accurately reproduced, and the alignment is effective.