Most of the stepper motors sold are, nowadays, hybrid motors; this means that they can be used in a bipolar unipolar configuration according to the connections of the driver. While a 6 wires hybrid stepper can be used in a unipolar or bipolar configuration, really interesting is the use of the series or parallel configuration for the 8 wires stepper motor.
 |
Unipolar Wiring: This picture shows how to connect an 8 wires hybrid stepping motor in an unipolar configuration. Naturally in thi case the motor can be driven by a traditional unipolar driver |
 |
Series connection: This kind of connection can be used only with bipolar drivers. It generates an high inductance (and torque) at low speeds. The wires are directly connected in the middle in a series configuration. |
 |
Parallel connection: The parallel connection is normally used when an high torque at high speeds is needed as a result of a lower inductance. |
The purchase of an hybrid motor, even if a little more expensive, is generally considered a good idea because at any moment the configuration can be changed according to the driver and the speed necessary to drive the cnc machine but it is important even consider the current needed by the same hybrid motor accordingly to the wiring configuration. In this case we have always to pay a look to the pdf of the motor were are always clearly reported the current levels of the different configuration.
Just as example a KL23H251 motor (nema 23) pdf reports:
|
Voltage |
Current |
Resistance |
Torque |
|
|
Unipolar |
4.32 |
2.4 A |
1.8 |
113 |
|
Bipolar (series) |
6.12 |
1.7 A |
3.6 |
156 |
|
Bipolar (parallel) |
3.06 |
3.4 A |
0.9 |
156 |
... and we are talking about the same motor.
