How to achieve precise servo control:
1) There is a problem of AC zero crossing, so the AC current can be controlled by a half cycle as a pulse.
2) AC motor, a magnetic pole, a phase problem, to the phase group as the unit commutation, phase control can be accurately achieved;
3) DC motor, to the coil unit for commutation, you can coil unit for the control of DC motor;
These factors above are the basic basis for servo motor control. As we all know, in order to realize the need of servo control, people have already invented stepping motor and pulse motor. The core technology of servo control is to make the motor stepping , No stepper motor can not achieve servo control;
Stepping servo control principle:
1) For example, a DC motor, a pulse current in units of slots will rotate the motor rotor through an angle of 360 / slot;
2) For example, the AC motor, a pulse current in the phase group, will rotate the motor rotor through an angle of 360 / (number of poles: 2P times the number of phases);
3) Although we can not achieve “an exact 1/10 cycle, 1/100 cycle, 1/1000 cycle, 1/10000 cycle …” command pulses, we can achieve accurate dc current pulsing 1/16 week (the number of slots is 16)
4) Although we can not “accurately turn 1/10, 1/100, 1/1000, 1/10000 … in one command pulse”, we can achieve the accurate Over 1/12 weeks (the number of poles is 4, the number of phases is 3)
5) Of course, stepper pulse motor, we can accurately turn a current pulse 1/36 weeks or more;
6) In this way, we want to achieve high precision workpiece translation control how to do?
7) We all know that the manual manual adjustment knob coarse, and fine adjustment knob;
8) We also know micrometers of precision measurement tools;
9) In this way we know how to precisely control the workpiece translation using an AC motor with an AC pulse that can be rotated exactly 1/12 of a week:
① between the motor and the lead screw through a reducer drive, the motor speed increased, so as to achieve a current pulse so that the screw rotation 1/10 weeks, 1/100 weeks, 1/1000 weeks, 1/10000 weeks Accurate control;
② For example, a 4-pole 3-phase AC motor, in accordance with the phase sequence of three-phase AC, each pass 12 AC half-cycle pulse, turn one week;
③ deceleration ratio between the motor and the screw is 500, that is, each access to 12 × 500 AC half-pulse motor to 500 weeks turn, turn the screw a week;
④ screw a week, the workpiece translated a pitch 6mm;
⑤ so that we achieve an AC pulse so that the screw turned 12 × 500 = 1/6000 weeks, the workpiece translation 1 pitch / 6000 × 6mm / 6000 = 0.001mm precision control;
⑥ our indeed achieved a current pulse, the workpiece accurately translated 0.001mm;
10) Cite another one every day to see the precise control, watch the second hand clock, calculate the second hand every second turn 360/60 = 6 degrees, minute hand turn how many degrees? Clock how many degrees turn?
11) Calculate the second hand for every second 360/60 = 6 degrees, the minute hand turned 1/10 degrees, the hour hand turned 1/120 degrees;
12) In order to achieve accurate control of 1 second, people use mechanical spring pendulum, gravity pendulum, electronic crystal and other means;