Stepper Motor Drivers

Stepper motors operate differently from DC or DC motors. A stepper motor is a brushless synchronous motor consisting of a rotating part, the so-called rotor, and a non-rotating part, the stator. The stator is equipped with coils that generate an electromagnetic field and whose windings are switched on and off in a targeted manner, whereby the rotor starts to rotate. The rotation angle can be influenced by controlling the coils. A revolution consists of a certain number of steps of the same size. Each individual step requires a pulse to be performed. As the pulse frequency increases, the step motion switches to a continuous rotation motion. As a rule, industrial motors generate 200 steps per revolution. In other words, to fully rotate the axis in the motor once, 200 discrete steps are required.

Depending on their design, several types of stepper motors can be distinguished: Reluctance stepper motors have a serrated soft iron rotor. They achieve a high speed and an exact step angle, but produce only a small torque. Permanent magnet stepper motors, on the other hand, are equipped with a rotor in the form of a cylindrical permanent magnet. They produce a higher torque than reluctance stepper motors, but work at less precise step angles. Hybrid stepper motors are, so to speak, a mixed form of reluctance and permanent magnet stepper motors. They produce a high torque, precise step angles and are today the most widespread.

Stepper motors are brushless and therefore wear-free than conventional electric motors, but they must be controlled using a controller in order to be able to rotate. This is the task of stepper motor drivers. As the name suggests, they primarily have the function of driving the motor, but they also serve the targeted stepper motor control by controlling, for example, the rotational speed, direction of rotation, turning force or turning position.

Stepper motor drivers work together with a so-called stepper motor indexer or stepper motor controller, which is usually connected upstream. It provides step and direction control signals that the stepper motor driver receives and converts into electrical signals required to operate the motor. Via a suitable interface (e.g. RS-232 or RS-485), communication with the stepper motor indexer is ensured. It can be connected to a PC whose commands transform into the appropriate step and direction control signals and finally forward to the stepper motor driver. Versions for stand-alone operation are also available.

Stepper motor drivers influence the current flow that flows through the windings in the motor and ultimately determines how high or low the speed and torque are. Some drivers also have a built-in clock generator that allows the speed to be adjusted from the outside, for example by operating a joystick. The current flow rate and the time it takes to "energize" the windings depends on the inductance of the motor.

There is no fixed method of configuring motor drivers. The configuration is different depending on the driver and board. Often the corresponding software is used, but there is also the possibility to make settings via hardware. This is usually the case when one or more DIP switches are on the board.

In our online shop you will find a large selection of stepper motor drivers in the form of circuit boards, modules and step sticks, which are suitable for different application areas.

Buying Criteria for Stepper Motor Drivers – What's it all about?

When selecting a suitable stepper motor driver, the maximum phase current must first be taken into account. Maximum phase currents are specified to counteract the development of heat in the coils of the motor. You can filter on this criterion in our online shop.

In order to prevent overheating and potentially resulting damage to the electronics, stepper motor drivers should ideally be equipped with a heat sink or fan. Some drivers simply switch themselves off automatically in case of too high heat generation. It is possible to retrofit drivers with a heat sink. However, it is important to ensure compatibility between the two components. Refer to the manufacturer's description.

Interfaces can be a decisive purchasing criterion if the stepper motor driver is to be controlled via a PC. Not every laptop or desktop PC has an RS-232 or RS-483 interface. In such cases, it makes sense to select a driver with a USB connection.

If you want to control your stepper motor driver with an Arduino or other microcontroller, make sure that the respective version is compatible with it. Relevant data can be found in the manufacturer's description.