12 features of stepping motor drive systems
(1) Even if it is the same stepping motor, when using different drive schemes, its torque-frequency characteristics are quite different.
(2) When the stepper motor is working, the pulse signal is applied to the windings of each phase in turn in a certain order (the ring distributor in the drive controls the way the windings are turned on and off).
(3) The 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 by pulse, the power supply voltage is its highest voltage, not the average voltage, so the stepper motor can exceed Its rated value range works. But the selection should not deviate too far from the rated value.
(4) The stepper motor does not accumulate errors: the accuracy of the general stepper motor is three to five percent of the actual step angle, and it does not accumulate.
(5) The maximum temperature allowed by the appearance of the stepper motor: If the temperature of the stepper motor is too high, the magnetic material of the motor will be demagnetized first, resulting in a decrease in torque and even loss of synchronization. Therefore, 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 external temperature of the stepper motor is completely normal at 80-90 degrees Celsius.
(6) The torque of the stepper motor will decrease with the increase of the speed: when the stepper motor rotates, the inductance of each phase winding of the motor will form a back electromotive force; the higher the frequency, the greater the back electromotive force. Under its action, the phase current of the motor decreases as the frequency (or speed) increases, resulting in a decrease in torque.
(7) The stepper motor can run normally at low speed, but it cannot start if the frequency is higher than a certain frequency, and there is a whistling sound. The stepper motor has a technical parameter: no-load start frequency, that is, the pulse frequency that the stepper motor can start normally under no-load conditions. If the pulse frequency is higher than this value, the motor cannot start normally and may lose steps or stall. In the case of load, the starting frequency should be lower. If the motor is to rotate at a high speed, the pulse frequency should have an acceleration process, that is, the start frequency is low, and then increase to the desired high frequency according to a certain acceleration (the motor speed rises from low speed to high speed).
(8) The power supply voltage of the hybrid stepping motor driver is generally a wide range (for example, the power supply voltage of IM483 is 12～48VDC), and the power supply voltage is usually selected according to the working speed and response requirements of the motor. If the motor has a high working speed or a fast response requirement, then the voltage value is also high, but note that the ripple of the power supply voltage cannot exceed the maximum input voltage of the drive, otherwise the drive may be damaged.
(9) The power supply current is generally determined according to the output phase current I of the driver. If a linear power supply is used, the power supply current can generally be 1.1 to 1.3 times I; if a switching power supply is used, the power supply current can generally be 1.5 to 2.0 times I.
(10) When the offline signal FREE is low, the current output from the drive to the motor is cut off, and the motor rotor is in a free state (offline state). In some automation equipment, if the motor shaft is required to be directly rotated (manual mode) when the drive is powered off, the FREE signal can be set low to take the motor offline for manual operation or adjustment. After manual completion, set the FREE signal high again to continue automatic control.
(11) Use a simple method to adjust the direction of rotation of the two-phasestepping motor after it is energized, just swap the A+ and A- (or B+ and B-) connections between the motor and the drive.
(12) The four-phase hybrid stepping motor is generally driven by a two-phase stepping driver. Therefore, the four-phase motor can be connected into two phases by using the series connection method or the parallel connection method when connecting. The series connection method is generally used in the occasions where the motor speed is low. At this time, the driver output current required is 0.7 times of the motor phase current, so the motor heat is small; the parallel connection method is generally used in the occasions where the motor speed is high (also known as high-speed connection). Method), the required driver output current is 1.4 times the motor phase current, so the stepper motor generates more heat.