The characteristics of stepper motor：
(1) The stepper motor has no accumulated error: the accuracy of the general stepper motor is 3% to 5% of the actual step Angle, and it does not accumulate.
(2) When the stepper motor is working, pulse signals are added to each phase winding in turn in a certain order (the ring divider in the driver controls the way of winding switching on and off).
(3) Even for the same stepper motor, when using different driving schemes, its moment-frequency characteristics are very different.
(4) Stepper motor is different from other motors, its nominal rated voltage and rated current are only reference values; And because the stepper motor is powered in pulse mode, the supply voltage is its highest voltage, rather than the average voltage, so the stepper motor can work beyond its rated range. But the choice should not deviate too far from the rating.
(5) the maximum temperature allowed by the appearance of the stepper motor: the high temperature of the stepper motor will first demagnetize the magnetic material of the motor, resulting in a decrease in torque and even out of step, so the maximum temperature allowed by the appearance of the motor should depend on the demagnetization point of different magnetic materials of the motor; Generally speaking, the demagnetization point of magnetic materials is above 130 degrees Celsius, and some are even as high as 200 degrees Celsius, so the appearance temperature of stepper motor is completely normal at 80-90 degrees Celsius.
(6) The torque of the stepper motor will decrease with the increase of speed: when the stepper motor rotates, the inductance of the winding of each phase of the motor will form a reverse electromotive force; The higher the frequency, the greater the reverse electromotive force. Under its action, the phase current of the motor decreases with the increase of frequency (or speed), which leads to the decrease of torque.
(7) The stepper motor can operate normally at low speed, but if it is higher than a certain frequency, it can not start, and accompanied by noise. Stepper motor has a technical parameter: no-load starting frequency, that is, the pulse frequency at which the stepper motor can normally start under no-load conditions. If the pulse frequency is higher than this value, the motor cannot start normally, and step loss or rotation blocking may occur. In the case of load, start frequency should be lower. If the motor is to reach high speed, the pulse frequency should be accelerated by starting at a low frequency and then increasing to the desired high frequency with a certain acceleration (the motor speed increases from low to high speed).
(8) The four-phase hybrid stepper motor is generally driven by a two-phase driver, so the four-phase motor can be connected into two phases by series connection or parallel connection method. Series connection method is generally used in the occasion of low motor speed, at this time, the output current of the driver is 0.7 times of the motor phase current, so the motor heat is small; And connection method is generally used in the occasion of high motor speed (also known as high-speed connection method), the required driver output current is 1.4 times of the motor phase current, so the motor heating is larger.
(9) The power supply voltage of the hybrid stepper motor driver is generally a wide range, and the power supply voltage is usually selected according to the working speed and response requirements of the motor. If the motor is running at a high speed or responding quickly, the voltage value is also high, but pay attention to the ripple of the supply voltage should not exceed the maximum input voltage of the driver, otherwise the driver may be damaged.
(10) The power supply current is generally determined according to the output phase current of the driver. If linear power supply is used, the power supply current is generally desirable 1.1 ~ 1.3 times; If switching power supply is used, the power supply current is generally 1.5 ~ 2.0 times.
(11) When the offline signal is low level, the current output from the driver to the motor is cut off, and the motor rotor is in a free state (offline state). In some automation equipment, if it is required to turn the motor shaft directly when the drive is powered on (manual mode), the signal can be set low to take the motor offline for manual operation or adjustment. After manual completion, the signal is raised to continue automatic control.
(12) Adjust the rotation direction of the two-phase stepper motor with a simple method, just switch the wiring between the motor and the driver.
