Stepper motors are Brushless DC motors with discrete step rotation. Its coils are organized in groups which are called phases.
When phases are energized in a sequence, the motor moves a step.
are two types of commonly available stepper motor drivers, unipolar driver and bipolar driver.
It also influences the motor winding connection. We will focus on bipolar driver-based stepper motor in this article and find out the pros and cons of its two winding connection scheme, series, and parallel.
Why is the winding connection scheme important?
The motor winding connection influences the operating characteristics (operating speed, torque and power output) of the stepper motor.
Connecting a motor in either series winding or parallel will enable you to get optimal performance according to your application.
Commonly the 4-lead stepper motors are factory manufactured with some predefined winding connection according to certain applications.
So, you can’t alter its winding connection. But 8-lead stepper motors have all its leads exposed for the user.
These motors are flexible to modify between two connection schemes. So, you need an 8-lead stepper motor for a perfect comparison.
In the series configuration, two different windings are connected in series.
In the configuration, two coils are connected to one please and the other two coils in another phase.
The polarity of the coils in the series configuration is to be noticed.
As two coils are opposite to each other, they are 180° apart in space.
Thus there needs to be a 180° phase difference in the two coils. This is achieved by connecting one coil backward to another.
This way in two coil current flows in the same direction to get an effective magnetic field and not canceling out each other to offer a stalled condition.
As being in series to each other, the effective impedance of the coils will add up to offer greater impedance.
The motor heating and power consumption lowers for fixed voltage drives
Output torque reduces large R/L thus considerable time constant
In the parallel configuration, two different windings are connected in parallel, and they are also connected with a 180° phase difference.
In the parallel configuration, the effective impedance of the coils decreases with a decrease in R/L ratio making the time constant smaller.
Improved speed range and high-speed stability
Increased torque and power output
Dramatically increased power consumption in the motor and driver circuit
So, after discussing the pros and cons of both the configuration scheme, you can see whether to use the series connection or parallel you need to know where you are using it.
These Brushless DC motors have a wide range of applications ranging from robotics to radar connections.
It can also be controlled digitally thus making it very popular. This is in brief about what you need to know before dealing with series or parallel connection of stepper motors.