# Stepper motors and drivers: full step, half step and micro step

by：V&T Technologies     2020-01-17
The stepping driver controls the working mode of the stepping motor. Stepping motors have three commonly used excitation modes, full step, half step and micro step. These excitation modes have an impact on the operating characteristics and torque provided by the motor. Whenever an input pulse is applied to the motor, the stepping motor converts the electronic signal into mechanical motion. Each pulse moves the Axis in fixed increments. If the resolution of the stepping motor is 1. 8 ° , Then, the shaft rotates a full circle, in the full step of operation, the stepping motor needs to receive 200 pulses, 360 °÷1. 8 = 200. There are two types of full-step excitation modes: single-phase on (one phase on)Step (Figure 1) The motor only operates under the condition of single-phase power supply. Compared with drivers of other excitation modes, this mode requires the least amount of power. Open in two phases (two phase on)Step (Figure 2) In the middle, the motor runs under the condition that the two phases are electrified at the same time. This mode improves torque and speed performance. Two-phase opening provides more torque than single-phase opening (About 30% to 40%) However, it requires twice the power from the drive. The half-step excitation mode is a combination of single phase on and two phase on in the full-step phase mode. Its basic step angle is only half. As the resolution of the angle increases, this smaller stepping angle provides smoother operation. The torque generated by half step is about 15% less than that of the two-phase full-step torque. However, when the single-phase is energized, the improved half step eliminates the reduction of torque by increasing the current applied to the motor. See Figure 3: Micro-step, to achieve better control and more stable operation, micro-step can be the basic step of the motor is divided into 256 times, so that the small step is smaller. Micro drivers use two 90 ° apart The current sine wave, which is very suitable for the smooth operation of the motor. We will see that the motor is running very quietly. By controlling the direction and amplitude of the current in each winding, the motor characteristics are improved, the resolution is improved, the vibration is smaller, and the operation is more stable. Because sine waves interact, the transition from one winding to another is smoother. When the current in one winding increases and the current in the other winding decreases, smooth stepping and maintaining torque output will occur. See Figure 4: TAG stepping, motor driver, stepping driver, micro stepping, full step, half step excitation
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