Differences Between DC Motors and Stepper Motors: Which to Use?

In this article, you will learn about the differences between DC motors and stepper motors. Motors are the basis of countless applications in electronics, robotics, and automation. Whether you are building a robot, controlling a CNC machine, or powering a fan, choosing the right motor is crucial. We will explain how motors work, what their advantages and disadvantages are, and what applications exist. This way, you can make a well-considered choice for your project.

A DC motor converts electrical energy into mechanical energy. This motor is also called a direct current motor. It works on the basis of electromagnetic principles. When voltage is applied, current flows through the coils in the rotor. That field works together with permanent or electromagnets in the stator. This creates a force. That force sets the rotor in motion. The motor rotates continuously. This happens as long as there is voltage on the motor. The result is a constant rotation. The speed depends on the voltage. The load on the motor also plays a role. This makes the operation absolutely robust.

A typical DC motor has two main parts. The stator is stationary and contains the magnets. The rotor spins and contains the coils. In traditional motors, carbon brushes provide current to the rotor. A commutator reverses the current periodically to maintain rotation. Bearings reduce friction and ensure smooth operation. These parts work together very efficiently at all times.

There are two main types of DC motors. The first type is the brushed motor. This motor has a simple control with DC voltage. It is cheap and widely used. Brushed motors reach high speeds. They are used in toys and fans. A disadvantage is that the carbon brushes wear out due to friction. This requires extra maintenance. The second type is the brushless motor. This type of motor is also called BLDC. It has no carbon brushes and is therefore more durable. The brushless motor works more efficiently and produces less heat. It offers better torque control. However, the control is more complex. A special electronic controller is required for this. This makes this motor generally more expensive than the brushed motor. Both types have their own advantages and disadvantages. Each type of motor fits perfectly in various situations and applications.

DC motors are used in many applications. Fans and pumps often use this motor. Think of computer coolers and air conditioning systems. Electric tools such as drills and grinders are also used with them. In industry, motors ensure stable movement. Conveyor belts run smoothly. In model building and toys, they are used in electric cars and drones. They offer simplicity and speed. Their performance is highly valued.

A stepper motor works differently than a DC motor. Instead of rotating continuously, the rotor moves in fixed steps. This makes the motor ideal for applications that require precise positioning. The motor consists of a stator with multiple coils and a rotor. The coils are energized in a certain order. This causes the rotor to move in steps. The step size is often expressed in degrees, such as 1.8° per step. Microstepping can improve precision by allowing smaller steps. There are two types of stepper motors.

The unipolar motor has simpler control by central taps per coil. This makes the motor cheaper, but the torque is often lower and the efficiency is not optimal.
The bipolar motor has a higher torque and is more efficient, but the control is more complex. This requires a driver and H-bridge, which means that more electronics in knowledge is needed.

Stepper motors offer several advantages. They provide precise and repeatable movement, which is useful for applications such as 3D printers and CNC machines. These motors maintain torque when stationary, eliminating the need for braking systems. Open-loop control is often possible, eliminating the need for external feedback. Disadvantages include a limited speed (less than 2000 RPM) and torque degradation at high speeds, which can result in step loss. They also consume constant current, even when stationary.

Stepper motors are used in many areas. Think of 3D printers, for positioning the print head and bed. In CNC machines and engraving machines they are used to make precise cuts. Robotics uses the motor for repeatable movements. Camera and telescopic systems need them for smooth movements and tracking of objects. Precision instruments, such as those in medical technology, use stepper motors for precise movements without external feedback.

Both engine types have their own strengths. Below we compare the most important features:

Precision and Control

• DC motor:
  • Runs continuously and is less suitable for exact position determination.
  • For precise positioning, additional equipment such as an encoder is required.
• Stepper motor:
  • Moves in discrete steps, allowing very precise positions to be achieved.
  • Can even perform extra fine steps with microstepping, without external feedback.

Speed and Torque

• DC motor:
  • Can reach high speeds, up to 10,000 RPM.
  • Suitable for applications where speed and variable torque are important.
• Stepper motor:
  • Limited to lower speeds (often below 2000 RPM).
  • Provides stable torque at standstill, but loses this torque at higher speeds.

Energy Consumption and Efficiency

• DC motor:
  • Brushless DC motors in particular are very efficient.
  • Consumes no energy when stationary.
• Stepper motor:
  • Constantly consumes power even when the motor is not moving.
  • This can lead to higher energy consumption, especially during prolonged periods of standstill.

Control and Complexity

• DC motor:
  • Easy to control with variable voltage or pulse width modulation (PWM).
  • Direction of rotation can often be easily reversed with an H-bridge.
• Stepper motor:
  • Requires a special driver that energizes the coils in the correct sequence.
  • The control is more complex and requires precise pulse control.

Lifespan and Wear

• DC motor:
  • Traditional brush motors can have a shorter lifespan due to wear and tear of the carbon brushes.
  • Brushless variants offer a longer lifespan.
• Stepper motor:
  • Since they have no brushes, wear and tear is generally minimal.
  • Suitable for long-term and reliable use when applied correctly.

The choice between a DC motor and a stepper motor depends on the specific requirements of your project. Below you will find a practical guide:

Choose a DC motor if you:

• Need high speeds and continuous rotation: For example for fans, electric vehicles or conveyor belts.
• Simple control is important: With minimal electronic components and simple PWM control.
• Cost-efficiency and wide availability are essential: DC motors are often cheaper and easier to obtain.
• Precise positioning is less important: Where constant, rapid rotation is sufficient.

Choose a stepper motor if you:

• Highly accurate positioning and repeatable movements are required: This is important for 3D printers, CNC machines, robotic arms and precision instruments.
• Movement in discrete steps or exact angles is required: Thanks to fixed step sizes and the possibility of microstepping.
• Open-loop control without complex external sensors is desirable: This simplifies control for applications that do not rely on feedback.
• A stable torque at standstill is important: Without the need for additional braking mechanisms.

Proper control is crucial for optimal use of both DC motors and stepper motors.

Control of DC motors:

• Direct control: Here the motor is connected directly to a voltage source. This is simple but offers few control options.
• Pulse Width Modulation (PWM): PWM allows the speed of the motor to be precisely controlled. The voltage is switched on and off quickly, which produces an average voltage.
• H-bridge circuit: This allows the motor's direction of rotation to be easily reversed. This is useful in applications where both speed and direction are important.

Controlling stepper motors:

• Specific drivers: The driver ensures that the coils are energized in the correct order. This is essential for smooth and accurate movement.
• Full steps and half steps: In full steps the motor moves by a fixed angle (for example 1.8°). In half steps the resolution is doubled.
• Microstepping: This technique makes it possible to divide the movement into even smaller steps. This results in a very smooth and precise movement. This is ideal for applications that require maximum accuracy.

Popular drivers for stepper motors include the A4988, DRV8825, TMC2209 and TB6600. For DC motors, various drivers are also available, such as the L298N, DRV8871 and TB6612FNG.

Regardless of the type of engine you choose, there are a number of pitfalls you may encounter. Here are some tips to avoid problems:

For DC motors:

• Insufficient power supply: Make sure the power supply provides sufficient voltage and current. This will allow the motor to run at the correct speed.
• Protection against current surges: Use flyback diodes (for example 1N4007). This protects the driver against voltage surges when starting or stopping.
• Optimal PWM settings: Experiment with different frequencies. For example between 1 kHz and 20 kHz for stable motor operation.
• Cooling: Monitor the temperature and use heat sinks or fans if necessary to prevent overheating.

For stepper motors:

• Correct current setting: Set the current limit accurately according to the datasheet of both motor and driver. Too high or too low current may affect the performance.
• Stable power supply: Make sure you have a power supply that matches the motor (often between 12V and 24V) to avoid unexpected resets.
• Use of microstepping: This helps to reduce vibrations and make the movement smoother.
• Check Wiring: Incorrectly wired coils can cause erratic movement. Always check wiring carefully.
• Controlled Acceleration: When starting up a stepper motor, it is important to build up the speed gradually to avoid losing steps.
• Limit switches: In systems such as CNC machines or robotic arms, limit switches can prevent damage. These switches stop the motor when mechanical limits are reached.

The choice between a DC motor and a stepper motor depends on the requirements of your project.

• If you value speed and easy control, choose a DC motor. These motors are ideal for applications such as fans, electric vehicles, conveyor belts and power tools.
• If you need precision and repeatable movements. Choose a stepper motor. Thanks to the discrete stepping motions and the ability to microstepping, these motors are perfect for 3D printers, CNC machines and robotics.

It is important to analyze the specifications of your project. Test the motor in a prototype, read the datasheets and check if the power supply and cooling are adequate. With the right knowledge and equipment you can choose the motor that best suits your application.

Whether you are a hobbyist or a professional engineer, the world of motors offers many possibilities. With a well-considered choice, you lay the foundation for success in any electronic, robotic or automated project.