Explanation of operation mode of control system of closed-loop stepping motor
Explanation of operation mode of closed-loop stepping motor control system 1. Closed-loop stepping motor control system was first in the form of encoder.
In the initial state, the system is quiescent due to excitation of one or several phases. After starting to work, the target position is first sent to the subtraction counter, and then,'Start'
The pulse signal is added to the control unit, and the control unit is in theStart'
Under the action of the pulse, the stepping command is immediately sent to the phase sequence generator to change the excitation once, and the subsequent pulse is generated by the encoder device.
Every time the encoder generates a pulse, the counter is reduced by 1. Therefore, the subtraction counter records the actual rotor position.
When the count of the subtraction counter is reduced to zero, a stop signal is sent to the control unit to prohibit subsequent stepping commands and the system stops working.
For low-resolution stepping motors, a slotted disk and photoelectric sensor are usually used as the combination of feedback encoders, and the number of notches is equal to the number of steps taken by the motor per revolution;
For high-resolution stepping motors, high-resolution incremental encoders, such as Rotary transformer incremental encoders and inductosyn incremental encoders, should be adopted.
Because the feedback encoder is expensive, and in order to place the encoder on the shaft of the stepping motor, the system is required to have a larger volume, these two major defects limit the application of closed-loop control system of stepping motor in Encoder form.
2. The closed-loop control system of stepping motor in the form of Waveform Detection the principle of the closed-loop control system of stepping motor in the form of waveform detection is (Or current caused by winding back potential)
The rotor position information is indirectly obtained and fed back to the control unit to generate control pulses to control the movement of the stepping motor.
The waveform detector is composed of simple electronic circuits and is cheap. If necessary, it can be directly installed in the logic circuit of the controller. The stepping motor does not need additional mechanical connection.
3. The closed-loop control system of stepping motor using current detection the closed-loop control of stepping motor using current detection is based on the fact that the phase current of some reactive stepping motors has positive or negative extreme values within a certain rate range. the concept is carried out.
The initial starting pulse is added to the system, and the motor starts. When the phase current reaches an extreme value, the peak detection line instantly generates a pulse or timing signal, which is fed back to the control unit as a subsequent pulse, the closed-loop control of stepping motor is realized.
It is worth noting that there may be several peaks in the conduction phase current and the cut-off phase current of the motor. Which state should be tested can be determined according to the actual operation of the motor, the current detection can be realized by inserting a small resistor with a known resistance value into the current loop to measure the voltage when the current passes through. The peak detection circuit generally adopts the analog differential method, the wave crest is expressed by di/dt passing through zero value.
Label: Stepping Motor closed-loop stepping motor Related reading: differences between closed-loop stepping motor and open-loop stepping motor relationship between stepping motor driver and automation industrial production technology TAG closed-loop stepping motor