Constant Current Drive Principle of Stepper Motor
In addition to the motor itself, the performance of stepper motors is also greatly affected by different driving methods and control methods. When choosing a stepper motor, you should also consider the driving method and control method. There are two drive methods for stepper motors: constant voltage drive and constant current drive. Most of the stepper drives currently on the market are based on constant current drive. Constant voltage drive is not commonly used due to large copper consumption.
The figure below shows the schematic diagram of a constant current drive chopper drive. When the rated current or the set drive current is I₀, if the current generated by the voltage on the coil exceeds the set current value I₀, the applied voltage V Turn off to reduce the current. If it is lower than the set current value I₀, the applied voltage V is turned on to increase the current to the set current value I₀. Repeat this to keep the current constant.
If the stepper motor rotates at low speed and is not driven by a constant current chopper, when the current flowing through the motor coil exceeds the rated current, the motor will generate a high temperature rise and may burn out. During high-speed operation, if the time applied to the voltage of one phase winding is less than t₀ in the figure below, the power supply cannot guarantee to provide the set current I₀ value, and it becomes a constant voltage drive. That is, when running at high speed, chopping can become a constant current drive.
The figure below shows the schematic diagram of a constant current drive chopper drive. When the rated current or the set drive current is I₀, if the current generated by the voltage on the coil exceeds the set current value I₀, the applied voltage V Turn off to reduce the current. If it is lower than the set current value I₀, the applied voltage V is turned on to increase the current to the set current value I₀. Repeat this to keep the current constant.
If the stepper motor rotates at low speed and is not driven by a constant current chopper, when the current flowing through the motor coil exceeds the rated current, the motor will generate a high temperature rise and may burn out. During high-speed operation, if the time applied to the voltage of one phase winding is less than t₀ in the figure below, the power supply cannot guarantee to provide the set current I₀ value, and it becomes a constant voltage drive. That is, when running at high speed, chopping can become a constant current drive.
Updated on: 15/12/2023
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