How do stepper motor drivers work

The current supply drawn from this will be in the range of mA to mA. The design of the power supply can be done based on the motor specifications. The power supply should be regulated to avoid the fluctuations within torque and speed. Drivers are mainly working in two modes like the pulse input mode as well as integrated controller mode. Based on the required operating system, one can select the desired combination.

The control of a stepper motor can be done with the help of a pulse generator offered through the consumer. The customer selects this input on the host programmable controller, and then enters the operation command. This kind of driver allows the stepper motor to be driving through a PC which is directly connected otherwise a programmable controller.

The different types of motor driver chips along with its features are listed below. High Current DRV 2. Two-phase-on driving gets no finer resolution than one-phase on, but it does produce more torque.

One-two phase-on driving has its name for the way the drive energizes either 1 or 2 phases at any specific time. In this driving method, also known as half-stepping, the drive energizes pole A shown in green … then energizes poles A and B … then energizes pole B … and so forth. One-two phase-on driving delivers finer motion resolutions. When two phases are on, the motor produces more torque.

One caveat here: torque ripple is a concern because it may cause resonance and vibration. Microstepping delivers very fine motion resolutions. By organizing their on and off functions in the proper manner, the system is able to sufficiently power the phases, and the motor is able to step through the process. A unipolar driver can be made within a decent budget. It is important to remember that this driver will only be able to power unipolar motors.

If you wish to power a bipolar motor, you will need two full-bridges. This enables the system to return the current to the steps. These can prove to be more challenging to make, but you can purchase H-bridge chips to ease the process. Stepper motor drivers rely on input from a separate source in order to function and create an output. The following four signals control the motor:. A cheap way to power a simple stepper motor is through a microcontroller. This is sufficient since these drivers only need a couple signals to operate.

The first is a step signal and the second, a direction signal. When the signal is low GND it goes in the opposite direction. A full-step typically needs two rectangular signals in quadrature.

In the pictures, the colors of the stator teeth indicate the direction of the magnetic field generated by the stator winding. The performance of a stepper motor — both in terms of resolution or step size , speed, and torque — is influenced by construction details, which at the same time may also affect how the motor can be controlled.

As a matter of fact, not all stepper motors have the same internal structure or construction , as there are different rotor and stator configurations. For a stepper motor, there are basically three types of rotors:.

The stator is the part of the motor responsible for creating the magnetic field with which the rotor is going to align. The main characteristics of the stator circuit include its number of phases and pole pairs, as well as the wire configuration. The number of phases is the number of independent coils, while the number of pole pairs indicates how main pairs of teeth are occupied by each phase.

Two-phase stepper motors are the most commonly used, while three-phase and five-phase motors are less common see Figure 5 and Figure 6. We have seen previously that the motor coils need to be energized, in a specific sequence, to generate the magnetic field with which the rotor is going to align.

Several devices are used to supply the necessary voltage to the coils, and thus allow the motor to function properly. Starting from the devices that are closer to the motor we have:. Figure 7 shows a simple representation of a stepper motor control scheme.

The pre-driver and the transistor bridge may be contained in a single device, called a driver. There are different stepper motor drivers available on the market, which showcase different features for specific applications. The most important charactreristics include the input interface. The most common options are:. Another important feature of a stepper motor driver is if it is only able to control the voltage across the winding, or also the current flowing through it:.

Another feature of the motor that also affects control is the arrangement of the stator coils that determine how the current direction is changed. To achieve the motion of the rotor, it is necessary not only to energize the coils, but also to control the direction of the current, which determines the direction of the magnetic field generated by the coil itself see Figure 8.