Why is the stepper motor connected with A+A-B+B-

The working principle of the stepper motor is based on the two-phase four-wire system. Specifically, A+A- constitutes a set of coils, representing the first phase; and B+B- constitutes another set of coils, representing the second phase. This design enables the motor to achieve precise position control and stepping motion by controlling the direction and phase of the current.
In stepper motors, the two-phase four-wire wiring method is very critical. Due to the reversible drive technology, each phase has a positive and negative pole. This means that by changing the direction of the current between A+ and A-, B+ and B-, the direction of rotation of the motor can be controlled. For example, when a positive current is applied between A+ and A-, and a reverse current is applied between B+ and B-, the motor rotates in one direction; otherwise, it rotates in the opposite direction.
This wiring method not only simplifies the design of the control circuit, but also improves the reliability and accuracy of the motor. By precisely controlling the magnitude and direction of the current, the stepper motor can achieve precise position adjustment within a predetermined step. This is crucial for application scenarios that require high-precision control, such as laser cutting, precision measurement, and robotics.
It is worth noting that the two-phase four-wire wiring method is not the only option for stepper motors. Depending on the specific application requirements, three-phase, four-phase or other multi-phase stepper motors can also be used. However, the two-phase four-wire system is still the first choice in many applications due to its simplicity and reliability.
In short, the A+A- and B+B- wiring methods of stepper motors are the basis for their efficient operation. By reasonably controlling the current of these two phases, precise position control and motion control of stepper motors can be achieved to meet the needs of various precision manufacturing and automation control.