Analysis and design of constant torque stepper motor driver
Thanks to the rapid development of electronic technology, there are many single-chip microcomputers and driver chips. The performance of stepper motor drivers made by many domestic manufacturers is very good, but the basic requirements of customers for drivers are the same: cost-effective, simple control, safe and reliable. The author designed a constant current chopper two-phase stepper driver based on L298+L297. The driver itself has a pulse signal source to facilitate some simple control, setup and use. In the whole and half-step control, the constant torque output can be maintained, which is superior to the performance of similar products on the market. Moreover, the driver has a large ripple current, constant torque output, reliable operation, and built-in pulse signal source for users to perform some simple control, which is very convenient to set up and use.
1. L298 chip is a high voltage, high current double H bridge power integrated circuit, which can be used to drive inductive loads such as relays, coils, DC motors and stepper motors. It has two reject inputs to protect the device from the input signal. The emitters of the triodes of each bridge are connected together, and the corresponding external terminals can be used to connect peripheral feedback resistors. Another input power source can be placed to allow logic to operate at low voltages.
2 stepper motor drive characteristics
The coil winding of the two-phase stepping motor is divided into +A/-A phase and +B/-B phase, ignoring the nonlinear factor between electromagnetic torque and current. To make the motor run smoothly and constant torque, the key is control. Current in the motor winding
3 circuit solutions
The stepping motor control driving circuit of the design comprises a power circuit, a control driving circuit and an overcurrent detecting circuit.
The stepping motor driver is suitable for two-phase and four-phase bipolar stepping motors with a driving voltage not exceeding 40V and a current not exceeding 2.0A, and basically covers the mainstream hybrid stepping motor below SIZE23. Widely used in medical equipment, analytical instruments, based on the main chip L297, L298 technology is mature, the price is cheap, the driver is cost-effective, the market sales are large, and the feedback is good.
