Starting from this paper, the driving circuits of two-phase bipolar stepping motor and two-phase unipolar stepping motor, as well as the driving methods of two-phase bipolar stepping motor and two-phase unipolar stepping motor will be introduced. Firstly, bipolar connection and unipolar connection are introduced.

Stepper motor: double pole connection and single pole connection

Stepper motor has two types: Bipolar connection type and unipolar connection type. Each type has its advantages and disadvantages. Therefore, it is necessary to understand their characteristics and select them according to the application requirements.

bipolar attachment

Bipolar connection and unipolar connection of two-phase stepping motor

The method of bipolar connection is shown in the figure, which adopts the driving mode of bidirectional current flow in one winding (bipolar driving). In this way, the structure of the motor is relatively simple and the number of terminals is less, but the driving circuit is more complex because the polarity of one terminal must be controlled. However, the winding utilization of this motor is good, and fine control can be carried out, so high output torque can be obtained. In addition, the back electromotive force generated in the coil can be reduced, so a motor driver with low withstand voltage can be used.

Unipolar connection

Bipolar connection and unipolar connection of two-phase stepping motor

As shown in the figure, the unipolar connection has a center tap and adopts the driving mode (unipolar driving) in which the current always flows in a fixed direction in one winding. Although the structure of the stepping motor is complex, the driving circuit of the stepping motor is simple because only the current on / off control is required. However, its winding utilization is poor, and only about half of the output torque can be obtained compared with bipolar connection. In addition, high back electromotive force will be generated in the coil when the current is on / off, so it is necessary to use a motor driver with high withstand voltage.

Key points:

・ bipolar connection

– adopt the driving mode of bidirectional current flow in one winding (bipolar driving).

– simple structure, but the driving circuit of stepping motor is complex.

– good winding utilization and fine control, so the stepping motor can obtain high output torque.

– the back EMF generated in the coil can be reduced, so the motor driver with low withstand voltage can be used.

・ unipolar connection

– it has a center tap and adopts the driving mode (unipolar driving) in which the current always flows in a fixed direction in one winding.

– the structure is complex, but the driving circuit of the stepping motor is simple.

– poor winding utilization. Compared with bipolar connection, stepper motor can only obtain about half of the output torque.

– due to the high back electromotive force in the coil, it is necessary to use a motor driver with high withstand voltage.

Editor in charge: Tzh

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