The stepper motor driver is an actuator that converts electrical pulses into angular displacement. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle (called “step angle”) in a set direction, and its rotation runs step by step at a fixed angle. The angular displacement can be controlled by controlling the number of pulses, so as to achieve the purpose of precise positioning; at the same time, the speed and acceleration of the motor rotation can be controlled by controlling the pulse frequency, so as to achieve the purpose of speed regulation and positioning.
- 1 Step motor driver phase number
- 2 Holding torque
- 3 Step motor accuracy
- 4 Surface temperature
- 5 Common Problem
- 6 How to choose a driver for stepper motor
- 6.1 Choose a suitable driver according to the rated current of the stepper motor
- 6.2 Choose the driver according to the required step angle
- 6.3 According to the AC and DC voltage provided by the power supply
- 6.4 Select the driver according to the voltage required to reach a certain speed when the stepper motor is running
- 7 How to set the stepper motor driver
- 8 How to wire the stepper motor driver
- 9 How to control the direction of the stepper motor driver
Step motor driver phase number
The number of phases of a stepper motor refers to the number of coil groups inside the motor. Two-phase, three-phase, four-phase, and five-phase stepper motors are commonly used. The number of phases of the motor is different, and the step angle is also different. Generally, the step angle of a two-phase motor is 1.8 degrees, a three-phase motor is 1.2 degrees, and a five-phase motor is 0.72 degrees. When there is no subdivision drive, users mainly rely on selecting stepping motors with different phase numbers to meet the step angle requirements. If a subdivision driver is used, the number of phases will become meaningless, and the user only needs to change the subdivision number on the driver to change the step angle.
After the driver is subdivided, it will make a qualitative leap in the running performance of the motor, but all of this is produced by the driver itself and has nothing to do with the motor and the control system. When using, the user needs to pay attention to the change of the step angle of the stepper motor, which will have an impact on the frequency of the step signal sent by the control system, because the step angle of the stepper motor will become smaller after subdivision. , The frequency of the stepping signal is required to be increased accordingly. Take a 1.8-degree stepper motor as an example: the step angle of the driver is 0.9 degrees in the half-step state, and the step angle is 0.18 degrees in the tenth subdivision. In this way, when the motor speed is required to be the same, the control system sends The frequency of the step signal is 5 times that of half-step operation in ten subdivisions.
Step motor accuracy
Generally, the accuracy of a stepping motor is 3~5% of the step angle. The deviation of a single step of the stepper motor will not affect the accuracy of the next step, so the error of the stepper motor will not accumulate.
The high temperature of the stepping motor will first demagnetize the magnetic material of the motor, which will cause the torque to drop or even lose. Therefore, the maximum allowable temperature of the motor surface should depend on the demagnetization point of different motor magnetic materials. Generally speaking, the demagnetization point of magnetic materials is above 130 degrees Celsius, so the surface temperature of the stepper motor is completely normal at 80~90 degrees Celsius.
- A. If the stepper motor is working in the resonance zone, the speed of the stepper motor can be increased by changing the reduction ratio.
- B. Use a driver with subdivision function, which is the most commonly used and easiest method. Because the phase current change of the subdivision driver motor is smoother than that of the half-step type.
- C. Change to a stepper motor with a smaller step angle, such as a three-phase or five-phase stepper motor, or a two-phase subdivided stepper motor.
- D. Changing to a DC or AC servo motor can almost completely overcome vibration and noise, but the cost is higher.
- E. Add a magnetic damper to the motor shaft. There are such products on the market, but the mechanical structure has changed a lot.
Since there are many types of stepper motors and drivers, users should be careful when choosing, so that they can choose the products they need with the best performance and the lowest price.
How to choose a driver for stepper motor
Choose a suitable driver according to the rated current of the stepper motor
Any stepping motor has its own rated current, and the maximum current of the driver selected with it cannot be lower than the rated current of the motor. The stepper motor drivers produced by Shanshe Motor have the function of current subdivision, that is, the current of the driver can be set according to the rated current of different motors. The same driver can be equipped with motors of different currents, as long as the rated current of the motor is less than The current when the drive is adjusted to the maximum can be used, otherwise the motor may be burnt.
Choose the driver according to the required step angle
Stepping motors on the market generally have step angles of 1.8°, 1.2°, and 0.72°. However, as customers have higher and higher requirements for the accuracy of the motor, the step angle also has different requirements. In order to meet the needs of customers, the motor The distance between manufacturers is achieved by the subdivision of the drive to achieve the subdivision of the motor. Shanshe motor drives have half-step and full-step, binary and quinary, and full subdivisions. Different subdivision drivers can be selected according to the needs of their products.
According to the AC and DC voltage provided by the power supply
The voltage is divided into AC voltage and DC voltage. The stepper motor driver has a rated voltage. When selecting the driver, choose a motor driver whose rated voltage is within the voltage range that the power supply can provide. If the rated voltage of the selected driver is too low, and the voltage provided by the power supply to the driver is higher than the rated voltage of the driver, it is easy to burn the driver.
Select the driver according to the voltage required to reach a certain speed when the stepper motor is running
How to set the stepper motor driver
The switches on the stepper motor driver include D1, D2, D4-D6, and the setting methods are as follows:
- D1 sets the way the driver sends pulses. If the stepper motor driver does not send pulses to control the motor itself, D1 is set to OFF. If the stepper motor driver itself sends out pulses, set D1 to ON.
- The D2 setting is also the way the driver sends out pulses, but the condition is that the D2 setting will only take effect when D1 is set to OFF.
- D4-D6 set the working subdivision number of the stepper motor, that is, the number of pulses required for the stepper motor to rotate one circle. The larger the subdivision, the higher the accuracy, but the easier it is to produce errors.
How to wire the stepper motor driver
Connect the CW+ and CP+ of the driver to the digital power supply +5V or +3V through the current-limiting resistor, use 470 current-limiting resistor for +5V, and 330 current-limiting resistor for +3V.
Connect CW- and CP- to the IO port of the single-chip microcomputer. If the low-level current absorption capacity of the single-chip microcomputer is less than 10mA, a transistor needs to be added to increase the current.
Write a program, send a square wave from the CW- pin, first send a 1KHz test (note that the duty cycle must be 50%), if the driver and the motor are connected correctly, the motor will rotate.
CP- is connected to another IO port, such as P1.2, which can control the direction of rotation of the motor.
The single-chip microcomputer cannot be directly connected to the stepper motor, it needs to be connected to the stepper motor through the driver.
4 wires should be connected between the driver and the stepper motor, and the two windings of the two windings of the stepper motor AB with a phase difference of 180 degrees are connected to the output of the driver. For the wiring sequence, please check the manual of the motor and the manual of the driver.
Before turning on the power, don’t forget to set the drive current, refer to the driver’s manual for setting.
How to control the direction of the stepper motor driver
Use pulse to control the direction, because the pulse has the number, it is conducive to precise control. Therefore, the direction of the stepper motor is controlled by pulses. The high level controls one direction, and the low level controls the other direction.
It is also controlled by two pulses. That is, the high level of one pulse controls one direction, and the high level of the other pulse controls the other direction