I don't know how much you know about the application and working principle of two-phase stepping motor driver. Today, I'll share the relevant contents in detail. I hope today's sharing can bring you different gains
Before understanding the application and working principle of two-phase stepping motor driver, let's take a look at what is stepping motor
Stepper motor is an open-loop control element that converts electric pulse signal into angular displacement or linear displacement. Under the condition of no overload, the speed and stop position of the motor only depend on the frequency and number of pulses of the pulse signal, and are not affected by the change of load. When the stepping driver receives the pulse signal, it drives the stepping motor to rotate a fixed angle in the set direction. The angular displacement is controlled by controlling the number of pulses to achieve the purpose of accurate positioning; At the same time, the motor speed and acceleration are controlled by controlling the pulse frequency to achieve the purpose of speed regulation.
Working principle of stepping motor
Stepping motor is a kind of induction motor. Its working principle is to use electronic circuit to supply power when DC becomes component, and control current according to polyphase sequence. When this current is used to supply power to the stepping motor, the stepping motor can work normally. The driver supplies power to the stepping motor in time, and the polyphase sequence controller
Although stepper motor has been widely used, stepper motor is not as conventional as ordinary DC motor and AC motor. It can only be used in the control system composed of double loop pulse signal and power driving circuit. Therefore, the use of stepping motor is not easy. It involves many professional knowledge such as machinery, motor, electronics, computer and so on. As the executive component of mechatronics, stepping motor is one of the key products of mechatronics, which is widely used in various automatic control systems. With the development of microelectronics and computer technology, the demand for stepping motor is increasing day by day. It is necessary in all fields of the national economy
Application of stepping motor
Selection of step angle: the step angle of the motor depends on the requirements of load accuracy. Convert the minimum resolution (equivalent) of the load to the motor shaft, and how many angles each equivalent motor should go (including deceleration). The step angle of the motor shall be equal to or less than this angle. At present, the stepping angle of stepping motor in the market generally has 0.36 degrees / 0.72 degrees (five phase motor), 0.9 degrees / 1.8 degrees (two-phase and four-phase motor) and 1.5 degrees / 3 degrees (three-phase motor)
Selection of static torque: the dynamic torque of stepping motor is difficult to determine at once. We often determine the static torque of motor first. The selection of static torque is based on the working load of the motor, and the load can be divided into inertia load and friction load. Single inertia load and single friction load do not exist. Both loads shall be considered when starting directly (generally at low speed). Inertia load shall be mainly considered when starting at accelerated speed, and friction load shall be considered when running at constant speed. Generally, the static moment should be within 2-3 times of the friction load. Once the static moment is selected, the base and length of the motor can be determined (geometric dimension)
Selection of current: for motors with the same static torque, the operating characteristics vary greatly due to different current parameters. The motor current can be judged according to the torque frequency characteristic curve (refer to the driving power supply and driving voltage)
Torque and power conversion: stepper motors are generally used for speed regulation in a large range, and their power changes. Generally, only torque is used to measure. Torque and power conversion are as follows:
P is the power, in watts, Ω is the angular velocity per second, in radians, n is the speed per minute, M is the torque, and the unit is Newton meter
P = 2 π FM / 400 (half step operation), where f is the number of pulses per second (PPS for short)
Stepper motor driver
1. Stepper motor is a special motor for control. Its rotation runs step by step at a fixed angle (called "step angle"), which is characterized by no accumulated error (accuracy of 100%), so it is widely used in all kinds of open-loop control. The operation of the stepping motor should be driven by an electronic device, which is the stepping motor driver. It converts the pulse signal sent by the control system into the angular displacement of the stepping motor, or every pulse signal sent by the control system will rotate the stepping motor by one step through the driver. Therefore, the speed of stepping motor is directly proportional to the frequency of pulse signal. Therefore, controlling the frequency of the step pulse signal can adjust the speed of the motor accurately; Controlling the number of stepping pulses can accurately locate the motor;
2. When the stepping motor is driven by the subdivision driver, its step angle becomes smaller. For example, when the driver works in the 10 subdivision state, its step angle is only one tenth of the 'inherent step angle of the motor', that is, 'when the driver works in the non subdivision full step state, the control system sends a step pulse and the motor rotates 1.8 °; When the subdivision driver works in the 10 subdivision state, the motor rotates only 0.18 ° ', which is the basic concept of subdivision. The subdivision function is completely generated by the driver by accurately controlling the phase current of the motor, which has nothing to do with the motor.
3. What are the advantages of drive segmentation and why it is recommended?
The main advantage of the subdivided driver is that it completely eliminates the low-frequency oscillation of the motor. Low frequency oscillation is the inherent characteristic of stepping motor (especially reactive motor), and subdivision is the only way to eliminate it. If your stepping motor sometimes needs to work in the resonance area (such as walking arc), selecting subdivision driver is the only choice. The output torque of the motor is improved. Especially for three-phase reactive motor, its torque is about 30-40% higher than that without subdivision. The resolution of the motor is improved. Because the step angle is reduced and the step uniformity is improved, "improving the resolution of the motor" is self-evident.
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