The composition of stepping motor control system the control system of stepping motor consists of programmable controller, circular pulse distributor and stepping motor power driver. PLC is used to generate control pulse in the control system;
A certain number of square wave pulses are output through PLC programming to control the rotation angle of the stepping motor and further control the feed rate of the servo mechanism;
At the same time, the pulse frequency is controlled by programming--The feed speed of the servo mechanism;
The loop pulse distributor distributes the control pulse output by the programmable controller to the corresponding winding according to the power-on sequence of the stepping motor.
The stepping motor controlled by PLC of stepping motor control system can adopt software circular distributor or hardware circular distributor.
PLC resources occupied by soft ring are more, especially the winding phase number of stepping motor M>
At 4 o'clock, full consideration should be given to large-scale production lines.
The hardware circular distributor is adopted. Although the hardware structure is slightly more complicated, it can save the number of I/O ports occupied by PLC, at present, there are many special chips in the market that can use stepping motor power driver to amplify the control pulse output by PLC to tens ~ Hundreds of volts, several amps ~ More than a dozen driving capabilities.
The output interface of General PLC has certain driving capability, while the load capacity of general transistor DC output interface is only more than ten ~ Dozens of volts, dozens ~ Hundreds of milliamperes.
But for the Power stepping motor, it requires dozens ~ Hundreds of volts, several amps ~ The driving capability is more than ten amperes, so the driver should be used to amplify the output pulse.
The stepping motor of the servo mechanism stops running when there is no pulse input, and the servo actuator is positioned.
When the displacement speed of servo actuator is required to be high, the high-speed pulse generator in PLC can be used.
The frequency of high-speed pulse of different PLC can reach 4000 ~ 6000Hz.
For the general servo mechanism on the automatic line, its speed can be fully satisfied.
If the servo mechanism adopts a hardware circular distributor, the number of I/O ports occupied by PLC is less than 5 points, generally only 3 points.
One point occupied by Port I is used as the starting control signal;
Port O occupies 2 points, one point is used as the pulse output interface of PLC, connected to the clock pulse input end of the hard ring of servo system, and the other point is used as the steering control signal of stepping motor, connect to the phase sequence distribution control end of the hard ring.
When the servo system adopts software circular distributor, the open-loop servo mechanism controlled by PLC is applied to the numerical control sliding table of a large production line, and each sliding table only occupies 4 I/O interfaces, thus saving the CNC control system, its pulse equivalent is 0. 01 ~ 0.
05mm, feed speed Vf = 3 ~ 15 m/min, fully meeting the process requirements and machining accuracy requirements.
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