First, stepper motor drive control system overview, usually, stepper motor drive system consists of three parts:
1 control circuit. Used to generate pulses to control the speed and direction of the motor.
2 drive circuit. It consists of pulse signal distribution and power drive circuitry. According to the pulse and direction signals input by the controller, it provides the correct power-on sequence for the windings of the stepper motor, and the high voltage and current required by the motor. At the same time, various protection measures are provided, such as overcurrent and overheating.
3 stepper motor. After the control signal is amplified by the driver, the stepping motor is driven to drive the load.
Second, stepper motor drive method comparison
1, single voltage drive
Single-voltage drive means that the winding is powered with only one direction voltage during the operation of the motor windings. L is the motor winding and VCC is the power supply. When the input signal In is high, a sufficiently large base current is provided to make the transistor T in a saturated state. If the saturation voltage drop is ignored, the power supply voltage acts on the motor winding. When In is low, the transistor is turned off and no current flows through the winding.
In order to make the winding current reach the preset current quickly when the power is turned on, it is connected in series with the resistor Rc; in order to prevent the change rate of the winding current when the T is turned off is too large, a large back electromotive force is generated to break through T and a diode is connected in parallel across the winding. D and resistor Rd provide a bleeder circuit for the winding current, also known as the freewheeling circuit.
The advantages of a single voltage power driver circuit are a simple circuit structure, few components, low cost, and high reliability. However, since the power consumption is increased after the series resistance, the entire power driving circuit has a low efficiency and is only suitable for driving a small-power stepping motor.
2, high and low pressure drive
In order to enable the winding to quickly reach the set current during power-on, the winding current rapidly decays to zero at turn-off, and at the same time it has a higher efficiency, and a high-low voltage drive mode appears.
Th and T1 are respectively the high pressure tube and the low pressure tube, Vh, V1 are the high and low voltage power respectively, Ih, I1 are the high and low end pulse signals respectively. The leading edge of the conduction is powered by a high voltage to increase the leading edge of the current, while the leading edge is followed by a low voltage to maintain the current of the winding.
High-voltage and low-voltage driving can obtain better high-frequency characteristics, but due to the constant conduction time of the high-pressure tube, the winding gets too much energy at a low frequency, and it easily causes oscillation. The stepper motor, stepper motor driver, and step are supplied. The servo technology engineers of servo motor and decelerating stepping motor can solve the problem of low-frequency oscillation by changing the conduction time of the high-pressure tube. However, the control circuit is more complicated than the single voltage and the reliability is reduced. Once the high-pressure tube is out of control, it will cause Too much current damages the motor.
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