DC Motors in Detail: Everything You Need to Know as a Mechanical Engineer!

From basics to high-tech: The world of DC motors for industrial applications.

What are the core components of a DC motor and their function?

A DC motor primarily consists of the stator (creates magnetic field), the rotor/armature (carries current-carrying windings) and the commutator. The commutator is crucial because it periodically reverses the direction of current in the rotor, enabling a continuous rotation . Carbon brushes transfer current to the commutator.

How is the speed of a DC motor for industrial applications regulated?

Speed regulation is usually achieved by adjusting the armature voltage (armature control range) for a broad spectrum or by influencing the excitation field (field weakening area), allowing for higher speeds at reduced torque. For precision applications, such as those often implemented by ATEK Drive Solutions, PI controllers are frequently used to achieve an accuracy of ±0.1%.

What advantages do brushless DC motors (BLDC) offer compared to conventional DC motors?

BLDC motors utilize an electronic commutation, eliminating the mechanical wear of brushes. This results in a longer lifespan, reduced maintenance effort, the possibility of higher speeds , and an increased efficiency, often over 90%. ATEK applies this technology in modern servo motors.

What is meant by regenerative braking in DC motors and what are its benefits?

Regenerative braking means that the DC motor operates as a generator while slowing down and feeds energy back into the grid. This is particularly advantageous in applications with frequent braking cycles, such as cranes, and can lead to energy savings of up to 15% as well as lower operating costs.

What criteria are crucial when selecting a DC motor for a specific industrial application?

Important selection criteria include the required rated torque (e.g., 5 Nm), the rated speed (e.g., 3000 RPM), the rated voltage (e.g., 24V DC), the duty cycle, and the environmental conditions including the required IP protection class. A precise definition of these requirements is essential for an optimal drive solution, as offered by ATEK.

What is armature reaction in DC motors and how can it be addressed?

Armature reaction is a distortion of the main magnetic field by the magnetic field of the armature current, which can lead to commutation problems and torque loss . Modern DC drives, like those developed by ATEK Drive Solutions, utilize reversal poles or compensating windings, to neutralize this effect and increase motor efficiency by up to 5%.

When is a series motor the right choice for my application?

A series motor is ideal when a very high starting torque is required, for instance, for starters, cranes or traction applications. Its torque can reach two to three times the rated torque . However, its speed is heavily load-dependent.

Can ATEK Drive Solutions also offer custom DC motor solutions?

Yes, ATEK Drive Solutions specializes in developing custom drive solutions. Thanks to our modular system and our expertise in gearbox construction and servo motor manufacturing, we can optimally adapt DC motors to your specific requirements , even for complex applications and special gearboxes.

DC motors are versatile drives that efficiently convert electrical energy into mechanical motion; the correct selection of motor type and precise control are crucial for optimizing industrial processes and can significantly increase system efficiency..

Modern brushless DC motors (BLDC) offer significant advantages such as a longer lifespan, lower maintenance effort, and an efficiency often exceeding 90%, making them ideal for demanding applications in automation and electromobility.

Well-thought-out control strategies, such as starting current limitation and regenerative braking, not only enhance performance but can also energy savings of up to 15% extend and increase the lifespan of the entire drive system..Discover the diverse applications, functioning, and latest developments of DC motors. A comprehensive guide for engineers and decision-makers.

DC motors are indispensable in modern drive technology. Whether in robots, machine tools, or conveyor systems – their versatility is impressive. Do you need a customized solution? Contact us!

Are you looking for the ideal DC motor for your application? Let us work together to find the perfect solution!

Request a drive solution now!

Introduction to DC motors

This article addresses DC motors – their fundamentals, high-tech applications, and the selection and optimization of suitable drives for machines.

Understanding fundamentals and significance

Der DC motor (also known as a DC motor), one of the earliest forms of electric motors, plays a central role in the industry. Its ability to efficiently convert electrical energy into precise mechanical motion is of great importance for numerous applications. ATEK Drive Solutions GmbH employs such DC drives, for example, in gear motor solutions to ensure precise positioning in the packaging industry.

The core principle: energy conversion

DC motors operate based on the Lorentz force: A current-carrying conductor located in a magnetic field experiences a force. This force generates a torque that sets the rotor in motion. This enables reliable drive systems, like those needed for conveyor belts at a constant speed of 0.5 m/s. The simple principle of operation of these motors allows for robust and versatile designs.

Variety for industrial requirements

The range of DC motors extends from small motors for medical devices to powerful drives for heavy industry. The specific requirements of an application, such as high starting torque or constant speed under varying load, determine the choice of suitable motor type. A correct selection of the electric motor optimizes the entire drive solution, as our experiences with custom electric motors show.Functionality and construction of DC motors

Overview of the central components

Ein DC motor essentially consists of a stator that generates the magnetic field and a rotor, also called an armature, that carries the windings. The commutator, also referred to as the pole changer, is a crucial component for continuous rotation as it periodically reverses the armature current. The material of the carbon brushes (e.g., a graphite-copper mixture) significantly influences the lifespan of the motor, especially in applications with over 10,000 switching cycles per day.

• Main components: The stator produces the stationary magnetic field while the rotor (armature) contains the current-carrying windings.
• Commutator (pole changer): This key element enables continuous rotational movement by purposefully reversing the current direction in the armature windings.
• Carbon brushes: They establish electrical contact with the commutator and transfer current; the choice of their material (e.g., graphite-copper alloys) is critical for the durability of the DC drive.
• Continuous torque: This is generated by the precise, commutator-controlled current reversal in the armature windings.
• Armature reaction: A typical challenge in DC motors, where the magnetic field generated by the armature current distorts the stator’s main field and can impair motor performance.
• Approaches to solutions: Modern designs often use reversal poles or compensating windings to neutralize the armature reaction and increase motor efficiency.

The commutator: Conductor of rotational movement

When the rotor reaches a so-called dead point, the commutator reverses the current direction in the armature windings using the carbon brushes. This process generates continuous torque. Especially precisely manufactured commutator surfaces are important to minimize brush wear and sparking – an aspect that is particularly significant in low-voltage servo motors. Challenge of armature reaction and its solution

Herausforderung Ankerreaktion und deren Lösung

The so-called armature reaction, or the magnetic field generated by the armature current, can distort the stator’s main field. This can sometimes lead to commutation problems and a loss of torque. Modern DC drives therefore often utilize reversal poles or special compensating windings to neutralize this effect, which can increase efficiency by up to 5%.Types of DC motors

Permanent magnet DC motors (PMDC)

Permanent magnet-DC motors (PMDC), in which permanent magnets in the stator generate the field, are characterized by a simple construction and cost efficiency. They are ideal for small applications such as pumps or fans (for example, for an airflow of 2 m³/min). Their advantages include good power density and straightforward control.

• Permanent magnet DC motors (PMDC): These motors are known for their simple construction, economy, and advantageous power density.
• Shunt motors (shunt motors): They ensure a relatively constant speed even under fluctuating load, making them well-suited for machine tools.
• Series motors (series motors): Characteristic of this type is a high starting torque, making them predestined for applications such as vehicle starters.
• Brushless DC motors (BLDC): Through electronic commutation, brush wear is avoided, leading to a longer lifespan and higher efficiency of these DC motors.
• Bell armature motors: These special motors have a rotor without iron, allowing for low inertia and high dynamics, which is why they are often used in medical technology.
• Compound motors (compound motors): They combine the characteristics of series and shunt motors and are used for specific performance profiles, such as in elevators.

Shunt and series motors

Shunt motors, also known as separately excited motors, offer the advantage of maintaining a constant speed even with changes in load, making them interesting for machine tools. In contrast, series motors (series wound motors) provide a particularly high starting torque, for example up to 20 Nm in vehicle starters. The type of field winding largely determines the characteristics of the respective DC drive.

Brushless DC motors (BLDC)

Brushless DC motors (BLDC motors) use electronic commutation, thus avoiding mechanical wear of brushes. This allows for a longer lifespan and higher speeds. They are especially suitable for demanding control of DC motors in automation. BLDC drives often offer higher efficiencies of over 90%.

Specialists: disc rotor and compound motors

Disc rotor motors, equipped with a coreless rotor, feature very low inertia and enable highly dynamic movements, as required in medical engineering. Compound motors, also known as dual series motors, combine the advantageous characteristics of series and shunt motors, making them suitable for applications such as elevators (gentle starting with constant speed). The selection of appropriate special motors can significantly enhance the performance of the respective application.Control and application of DC motors

Precisely control speed

The speed control of a DC motor typically occurs through the adjustment of the armature voltage (so-called armature control range) or by influencing the excitation field (field weakening range, which enables higher speeds at reduced torque). For precision control, such as required in textile machines to maintain a thread speed of ±0.1%, PI controllers are often used. A well-thought-out control strategy significantly increases efficiency and process quality.

1. Precise speed control: can be realized by varying the armature voltage or by specifically influencing the excitation field of the DC drive.
2. Control of starting current: The use of series resistors or special soft start devices is a common method to limit the high inrush currents of DC motors.
3. Regenerative braking: Many DC motors offer the possibility of feeding energy back into the grid during braking, which is particularly beneficial for frequent braking cycles.
4. Important selection criteria: When choosing an electric motor, torque, speed, the expected load cycle, environmental conditions, and the required IP protection class must be considered.
5. Definition of nominal values: A clear specification of nominal torque, nominal speed, and nominal voltage of the motor is crucial for design.
6. Efficiency increase: Elaborate control strategies and the use of regenerative braking methods greatly contribute to the efficiency and quality of the overall process.
7. Extension of service life: Measures such as limiting the starting current protect the drive train and can extend the service life of the motor.

Control the starting current

When starting DC motors high inrush currents can occur due to the low armature resistance, reaching five to ten times the nominal current. To manage this and protect components, series resistors or soft start devices are used that limit the current. Effective starting current limitation contributes to extending the lifespan of the entire drive train.

Recover energy with regenerative braking

DC motors offer the possibility to feed energy back into the grid while braking (utilization braking). This is particularly advantageous in applications with frequent braking cycles, such as cranes or electric vehicles, and can lead to energy savings of up to 15%. Regenerative braking not only increases efficiency but also reduces operating costs. ATEK, for example, offers solutions for UPS applications.

Important selection criteria to consider

Key selection criteria for a DC motor include the required torque, speed, load cycle, environmental conditions, and the IP protection class (e.g. IP54 for protection against dust and splash water). Particularly important are:

• Nominal torque (e.g. 5 Nm)
• Nominal speed (e.g. 3000 rpm)
• Nominal voltage (e.g. 24V DC)
• Permissible operating temperature
• Available installation space

A precise definition of the requirements for the drive optimizes its performance and helps to avoid misinvestments.Advantages and disadvantages of DC motors compared to

The strengths of the DC motor

include their simple speed control, high starting torque (especially in series motors that can reach two to three times the rated torque) and a wide usable speed range. They are often economical when uncomplicated control is sufficient, such as in adjustment drives in furniture. DC motors The simple control is a clear advantage of this type of motor. Keep the challenges in view

Disadvantages of conventional

include wear of the commutator and brushes, requiring regular maintenance and leading to a shorter lifespan compared to brushless variants (BLDC). Electromagnetic interference (EMI) due to sparking can also pose a challenge. DC motors Although modern brush materials and motor designs mitigate these effects, the inherent disadvantages remain. A 12V gear motor Ein 12V Getriebemotor with quality brushes can achieve a lifespan of around 3000 operating hours.

DC vs. AC motors

Classical, brushed DC motors are often more complex in design than many AC motors (AC motors), such as asynchronous motors, which are considered particularly robust and maintenance-free. Brushless DC motors (BLDC types), on the other hand, often offer better dynamics and higher efficiency than standard AC motors. The choice between a DC and an AC drive ultimately depends heavily on the specific requirements of the respective application.Future developments and trends in DC motors

Focusing on efficiency and power density

A key development trend in DC motors aims for a continuous increase in efficiency and power density. The use of new magnetic materials, such as neodymium-iron-boron (NdFeB), which allow for up to 30% higher torque density compared to conventional ferrite magnets, as well as optimized winding designs and improved cooling concepts lead to more compact and stronger motors. These advancements expand the application possibilities for DC drives and improve the performance of existing systems.

The rise of brushless technology

Brushless DC motors (BLDC motors) is gaining increasing importance. Their inherent advantages, such as longer lifespan, reduced maintenance, the possibility of higher speeds, and increased efficiency, are convincing in more and more application fields – from electromobility to demanding industrial automation. ATEK uses BLDC technology, for example, in its latest servomotors . The often already integrated drive electronics also simplifies the system integration of these motor types.

Smarter control and system integration

Advancements in microcontroller technology and sensors enable increasingly intelligent controls for DC motors. This includes more precise control algorithms, enhanced diagnostic capabilities, and deeper integration into Industry 4.0 concepts. In the future, motors could, for example, automatically report maintenance needs or optimally adjust their operation to changing load conditions. Networking and integrated intelligence are clear future trends in the field of DC drive technology.

DC motors remain important drive elements in numerous industries due to their versatility and continuous development. ATEK Drive Solutions is happy to assist you in selecting and implementing optimal drive solutions for your specific requirements.