1. Stepper Motor Driver Drv8825
2. Stepper Motor Driver
3. Stepper Motor Driver Circuit
4. Stepper Motor Driver A4988

A stepper drive is the driver circuit that controls how the stepper motor operates. Stepper drives work by sending current through various phases in pulses to the stepper motor. There are four types: wave drives (also called one-phase-on drives), two-phase on, one-two phase-on drives and microstepping drives. Oct 23, 2020 What is Stepper Motor Driver. A stepper motor driver (or stepper motor drive) is a circuit which is used to drive or run a stepper motor. It is often called a stepper motor driver. A stepper motor driver usually consists of a controller, a driver and the connections to the motor.

What is a stepper motor driver?

A stepper motor driver is an electronic device that is used to drive the stepper motor. By itself it usually does nothing and must be used together with a controller like PoKeys57CNC.

There are a lot of different types of stepper motor drivers but in general all do the same thing – move stepper motors.

Why do I need one?

Stepper motors require voltages and/or currents that the controller simply can’t produce. Therefor we need to use a stepper motor driver. This electronic device will transform our movement instructions from a controller in to a sequence where the winding in stepper motor will be turned on or off while still providing enough power to it.

All of this can of course be produced by a microcontroller driving a few FETs but the design and the programming would take time. Thankfully there are already made solutions.

Types of drivers

In general there are two types of drivers. The constant voltage drivers (L/R drivers) and constant current drivers (chopper drivers).

• constant voltage drivers (L/R drivers):
  • they are cheaper than constant current drivers
  • use voltage to produce torque
  • usually not efficient
  • worse performance than chopper drivers
• constant current drivers (chopper drivers):
  • more expensive
  • more complex circuits
  • use constant current to produce torque
  • much better performance than the L/R drivers

The constant current drivers are almost always used since there are many ICs available and offer much better performance. You can find integrated circuits which already have integrated FETs, these are usually meant for lower currents (up to a couple of A) since they are small and heat dissipation could be a problem. Another type uses external FETs and the maximum current is only limited by the external FETs used.

For example the PoStep25-32 uses an integrated circuit which has integrated FETs and can provide up to 2.5A unlike the PoStep60-256 which uses external FETs and can provide up to 6 Amps.

Microstepping

Stepper motors move in steps which is usually 1.8°,that is 200 steps per revolution. This can be a problem when we need small movements. One option would be to use some kind of transmission but there is also another way – microstepping. Microstepping means that we can have more than 200 steps per revolution and in turn have smaller movements. This option is already integrated in most ICs and can be configured by simply moving a jumper like on PoStep25-32.

When driving stepper motors with full steps the output of the stepper motor driver looks like a square signal and produces rough movements. The bigger the microstepping the more the output signal looks like a sine wave and the stepper motor moves more smoothly. But there is a downside to this. With increasing microstepping value the torque drops a quite lot and if the value is too great it could happen that the motor can’t produce enough torque to even turn. Usually 1/4, 1/8 or even 1/16 can produce satisfactory smooth movements while still producing enough torque.

The following image shows how the output changes when selecting different microstepping values. You can see that the output looks increasingly more like a sine wave.

So what do these values even mean?

Microstepping tells us how many micro steps should a stepper make to produce one full step. The 1/1 value tells us that the stepper must make one microstep to produce one full step (so there is no microstepping). Value of 1/2 is called a half step and tells us that the stepper motor must make 2 microsteps for one full step. This means that the stepper motor should make 400 steps for one full revolution. A value of 1/8 will tell us that the motor should make 8 microsteps for one full step and 1600 steps for one full revolution. The same principle applies for all of the microstepping values.

How to drive the stepper motor driver

Most stepper motor drivers have a step/dir input. This means there are only two signals needed for each driver. The step signal is used for making steps and looks like a PWM signal. Each pulse means that the stepper will move for one step (or microstep). The dir signal means direction and is used to signal in which direction (CW or CCW) will the stepper turn.

Conclusion

We have found out that the stepper motor driver is a must have if our design requires the use of a stepper motor since the controller can’t produce enough current and enough high voltage. There are different types but the chopper drivers offer the best performance. Also the microstepping offers a great solution at first sight but produces a problem of decreased torque. It is still extremely useful but must be used properly. There are a lot of different ICs available for driving the stepper motor and many already made solutions like PoStep25-32 and PoStep60-256 which provide plug and play solution and are easy to use.

And if you would like to learn more here is a great starting point.

p.s.: Article about stepper motor driver was SEO optimized with the help of slovenian SEO freelancer Seo-Praktik.si.

Stepper Motors (Motor Only)

Oriental Motor offers a wide range of stepper motors including; AlphaStep closed loop stepper motors, 2-phase stepper motors and 5-phase stepper motors available in frame sizes from 0.79 in. (20 mm) up to 3.54 in. (90 mm). Five geared type stepper motor solutions, encoder and brake options and various motor windings are offered.

• 0.79 in. ~ 3.54 in. (20 mm~ 90 mm) NEMA 8 ~ NEMA 34 frame size stepper motors
• Non-backlash, Low-backlash and Spur Gears available
• AlphaStep Closed Loop, 2-Phase and 5-Phase Stepper Motors
• Encoder and Electromagnetic Brake Options

Stepper Motor Drivers

Stepper motor drivers convert pulse signals from the controller into motor motion to achieve precise positioning.

• AC or DC Input
• AlphaStep Closed Loop, 2-Phase or 5-Phase Stepper Motor Drivers
• Pulse Input, Built-in Controller or EtherNet/IP™ and EtherCAT Compatible versions
• Board or Box Type

_{EtherNet/IP™ is a trademark of ODVA}

Speed Control Stepper Motors & Drivers

The CVK Series SC speed control system offers a simple configuration consisting of a stepper motor, driver and programmable controller. The operating speed, acceleration and deceleration time, running current can be set via the driver switches, and simply turning the FWD (RVS) input to ON or OFF allows for easy control.

• No pulse generator needed
• 2 speed settings are possible
• Compact and high torque stepper motor

Controllers / Network Gateways

Controllers and Network Gateways for use with motion control systems.

Stepper Motor Driver Drv8825

• Controllers for use with Pulse Input Drivers
• Network Converters/Gateways (RS-485 Communication)
  • EtherCat
  • CC-Link
  • MECHATROLINK

Stepper Motors & Drivers

A stepper motor is used to achieve precise positioning via digital control. The motor operates by accurately synchronizing with the pulse signal output from the controller to the driver. Stepper motors, with their ability to produce high torque at a low speed while minimizing vibration, are ideal for applications requiring quick positioning over a short distance.

Accurate Positioning in Fine Steps

A stepper motor rotates with a fixed step angle, just like the second hand of a clock. This angle is called 'basic step angle'. Oriental Motor offers stepper motors with a basic step angle of 0.36°, 0.72°, 0.9° and 1.8°.

Utilizing Hybrid Stepper Motor Technology

A hybrid stepper motor is a combination of the variable reluctance and permanent magnet type motors. The rotor of a hybrid stepper motor is axially magnetized like a permanent magnet stepper motor, and the stator is electromagnetically energized like a variable reluctance stepper motor. Both the stator and rotor are multi-toothed.

A hybrid stepper motor has an axially magnetized rotor, meaning one end is magnetized as a north pole, and the other end a south pole. Toothed rotor cups are placed on each end of the magnet, and the cups are offset by half of a tooth pitch.

Easy Control with Pulse Signals

A system configuration for high accuracy positioning is shown below. The rotation angle and speed of the stepper motor can be controlled with precise accuracy by using pulse signals from the controller.

What is a Pulse Signal?

A pulse signal is an electrical signal whose voltage level changes repeatedly between ON and OFF. Each ON/OFF cycle is counted as one pulse. A command with one pulse causes the motor output shaft to turn by one step. The signal levels corresponding to voltage ON and OFF conditions are referred to as 'H' and 'L' respectively.

Stepper Motor Driver

The Amount of Rotation is Proportional to the Number of Pulses

The amount the stepper motor rotates is proportional to the number of pulse signals (pulse number) given to the driver. The relationship of the stepper motor's rotation (rotation angle of the motor output shaft) and pulse number is expressed as follows:

The Speed is Proportional to the Pulse Speed

The speed of the stepper motor is proportional to the speed of pulse signals (pulse frequency) given to the driver. The relationship of the pulse speed [Hz] and motor speed [r/min] is expressed as follows:

Stepper Motor Driver Circuit

Generating High Torque with a Compact Body

Stepper motors generate high torque with a compact body. These features give them excellent acceleration and response, which in turn makes these motors well-suited for torque-demanding applications where the motor must start and stop frequently. To meet the need for greater torque at low speed, Oriental Motor also has geared motors combining compact design and high torque.

The Motor Holds Itself at a Stopped Positioning

Stepper motors continue to generate holding torque even at standstill. This means that the motor can be held at a stopped position without using a mechanical brake.

Once the power is cut off, the self-holding torque of the motor is lost and the motor can no longer be held at the stopped position in vertical operations or when an external force is applied. In lift and similar applications, use an electromagnetic brake type.

Closed Loop Stepper Motors and Drivers - AlphaStep

The AlphaStep consists of stepper motor and driver products designed to draw out the maximum features of a stepper motor. These products normally operate synchronously with pulse commands, but when a sudden acceleration or load change occurs, a unique control mode maintains positioning operation. AlphaStep models can also output positioning completion and alarm signals, which increase the reliability of the equipment which they operate.

Types of Operation Systems

Each stepper motor and driver combines a stepper motor selected from various types, with a dedicated driver. Drivers that operate in the pulse input mode and built-in controller mode are available. You can select a desired combination according to the required operation system.

Pulse Input Driver

The motor can be controlled using a pulse generator provided by the user. Operation data is input to the pulse generator beforehand. The user then selects the operation data on the host programmable controller, then inputs the operation command.

Built-in Controller Driver

The built-in pulse generation function allows the motor to be driven via a directly connected personal computer or programmable controller. Since no separate pulse generator is required, drivers of this type save space and simplify wiring.

Stepper Motor Driver A4988

Difference Between AC Input and DC Input Characteristics

A stepper motor is driven by a DC voltage applied through a driver. In Oriental Motor's 24 VDC input motor and driver systems, 24 VDC is applied to the motor. In the 100-115 VAC motor and driver systems, the input is rectified to DC and then approximately 140 VDC is applied to the motor (certain products are exceptions to this.)

This difference in voltage applied to the motors appears as a difference in torque characteristics at high speeds. This is due to the fact that the higher the applied voltage is, the faster the current rise through the motor windings will be, facilitating the application of rated current at higher speeds. Thus, the AC input motor and driver system has superior torque characteristics over a wide speed range, from low to high speeds, offering a large speed ratio.

It is recommended that AC input motor and driver systems, which are compatible over a wider range of operating conditions than DC input systems, be considered for your application.