What are Electric Motors and How Do They Work?

What are Electric Motors and How Do They Work?


6 December 2021

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The electro-mechanical mechanism that transforms electrical energy into mechanical energy is known as an electric motor. The motor, in other terms, is a device that produces rotating force. The interplay of magnetic and electric fields is crucial to the operation of an electric motor especially in cordless devices like cordless drills.

The Evolution of Electric Motors

Michael Faraday, a British physicist, is regarded as one of the most significant of the numerous 19th-century scientists who contributed to the discovery and development of electric motors. Faraday achieved the successful rotation of a wire using a magnet and a magnetic field created by an electric current in 1821. In 1831, he developed the law of magnetic induction, paving the way for considerable advancements in electric motors and generators.

📌 Many additional forms of electric motors, as well as architectures that might be called the classic DC motor, have been developed over time.

Following that, the practical electric motor was found rather than invented in 1872, when one of the generators on display at the Vienna World’s Fair began rotating on its own after being unintentionally linked to another generator. This led to the realization that the same principles applied to generators could also be applied to motors. Generators became a mainstay of many sectors in the twentieth century as a result of the fast rise in their practical application.

Electric Motor Components
Electric Motor diagram

Generators and Motors

Generators turn mechanical energy back into electrical energy, whereas electric motors convert electrical energy into rotation and various kinds of mechanical energy.

Despite their opposing tasks, motors and generators have a lot in common in terms of design and functioning. In truth, all it takes is a simple experiment with two model motors coupled together to show that an electric motor may also function as a generator.

The two sorts of machines have traditionally been designed independently due to the distinct manner in which they are employed.

How Do Electric Motors Work

Electric motors generate rotational mechanical force in the armature—located on the rotor or stator—around the shaft by using electrical current to produce rotating magnetic fields. To turn electric energy into intense bursts of force and produce dynamic degrees of speed or power, numerous motor designs employ the same basic premise.

Components of the Motor

While electric motors vary in form and kind, many of them comprise the following parts and assemblies (starting at the center and working outward):

✅ Windings
✅ Central motor shaft
✅ Ball and roller bearings (to reduce friction and wear)
✅ Brushes (in DC motors)
✅ Terminals (placed on the rotor, the revolving part, or the stator, the stationary component)
✅ Industrial Applications of Electric Motors
✅ Frame and end shields

Electric motors are used in a wide range of applications in industry. The following are examples of common industrial applications:

✅ Heavy-duty machinery
✅ HVAC systems
✅ Crushers
✅ Pumps
✅ Lathes
✅ Compressors
✅ Fans and Blowers

Electric Motor Sectional
Electric Motor Sectional

Electric Motors of Various Types

Electric motors come in a variety of designs with different operating and safety characteristics, but they may be divided into two types: alternating current (AC) and direct current (DC).

While the power source is the most noticeable distinction between the two motor types, each has its own set of features and uses. AC motors are capable of driving more sophisticated and delicate equipment, whereas DC motors are typically used to power larger equipment that requires less maintenance and control. Because AC motors can produce greater torque, many industry people believe them to be more powerful than DC motors.

AC Motor

The alternating current is converted into mechanical power by the AC motor. Induction motors, synchronous motors, and linear motors are the three types of motors. AC motors are the most often used in the business because they offer various benefits:

  • They are simple to construct
  • They are more economical due to lower start-up consumption
  • They are also sturdier and therefore generally have a longer lifespan
  • They require little maintenance
  • They are simple to construct

Single-phase and three-phase AC motors are the two types of AC motors:

Single-phase motors have the following characteristics:

  • The torque is determined by the electrical power (in kW).
  • The number of poles determines the spinning speed
  • The method of attachment: flange (B14, B5) or brackets (B3)
  • Competence
  • Because they are less strong, they are less industrial
  • They can be connected to the household power grid

Three-phase motors have the following characteristics:

  • A design that can transport substantially more electrical power than a single-phase voltage motor
  • Their application in industrial settings (about 80 percent)
  • Their application to infrastructure and equipment that requires a lot of electricity

DC Motor

A DC motor is a mechanism that transforms DC electrical power into mechanical power. Its operation is based on the basic idea that when a current-carrying conductor is put in a magnetic field, a force is applied to it, and torque is generated. DC motors are also highly prevalent in industrial settings because, depending on the format (see brushless motor issue), they offer considerable advantages:

🔸 They are precise and rapid

🔸 Their speed can be regulated by altering the supply voltage

🔸 They are simple to install, even in mobile (battery-powered) systems

🔸 The starting torque is great

🔸 They start, stop, accelerate, and reverse swiftly

Perks of AC vs. DC Motors

Each motor type has its own set of benefits that make it ideal for a variety of commercial and industrial applications. AC motors, for example, are versatile and simple to use. The following are some of their additional benefits:

  • Low beginning power requirements that safeguard receiving end components
  • Controllable beginning current levels and acceleration
  • VFD or VSD add-ons that can adjust speed and torque at various phases of use
  • Longer durability and life spans
  • Multi-phase setup capabilities
 AC vs. DC Motors

DC motors have their own set of benefits, including:

• Installation and maintenance are easier.
• High beginning power and torque
• Quick start-up, stop-up, and acceleration reaction times
• Available in a variety of standard voltages

Which is more powerful, an AC or a DC motor?

AC motors are typically thought to be more powerful than DC motors because they can create more torque with a higher current. DC motors, on the other hand, are more efficient and make greater use of their input energy. AC and DC motors are available in a variety of sizes and strengths to satisfy the power requirements of any business.

A photo of a brush motor model versus a brushless model
Brush motor vs a brushless motor

Brushless Vs Brushed DC Motors:

Brushed motors and brushless motors are the two most prevalent types of DC motors (or BLDC motors). DC brushed motors, as their names suggest, feature brushes that are utilized to commutate the motor and cause it to spin. Electronic control replaces the mechanical commutation function in brushless motors. A brushed or brushless DC motor may be utilized in numerous applications. They work on the same principles as coils and permanent magnets in terms of attraction and repulsion. Both offer benefits and drawbacks that may lead you to prefer one over the other, depending on the needs of your application.

Brushed Electric Motor

A carbon brush can be any of the following: It’s made up of one or more carbon atoms. One or more shunts and terminals are included.

📌 Brushes are made from five different brush grade families. Each one is tailored to a specific need and has its own manufacturing method.

Any specialist in motion control should be able to distinguish between brushed and brushless DC motors. Previously, brushed motors were fairly prevalent. Though brushless DC motors have completely replaced them, the correct DC motor of either type may make a project significantly more efficient.

✅ The following are the major components of a brushed DC motor:

  1. Stator—a permanent magnet-encased enclosure.
  2. Armature is a rotor with a number of electromagnets installed on it. Inside the stator, it spins freely.
  3. Commutator— A metal ring attached to the armature shaft is known as a commutator.
  4. Brushes— To maintain electricity flowing to the armature coils, carbon slabs remain in contact with the commutator.

✅ Benefits of a Brushed DC Motor

  1. Overall construction expenses are low.
  2. Rebuilding is a common way to extend the life of a product.
  3. Simple and low-cost controller
  4. For fixed speed, no controller is required.
  5. Ideal for use in harsh operating conditions

✅ The Drawbacks of a Brushed DC Motor

  1. Less effective
  2. Electrically noisy: The commutators’ switching motion causes a lot of electrical and electromagnetic noise by continually building and breaking inductive connections.
  3. Lifespan: Brushes and commutators wear out because they are in constant direct contact with the shaft.

Uses of Brushed DC motor

In home products and autos, brushed DC motors are still widely utilized. They also have a large industrial following due to the ability to change the torque-to-speed ratio, which is only possible with brushed motors.

Brushless Electric Motor

Brushless motors today overcome many of the drawbacks of brushed motors by combining higher output power, smaller size and weight, improved heat dissipation and efficiency, wider operating speed ranges, and extremely low electrical noise. Brushless motors feature no electrical connections that might wear out, resulting in greater dependability and shorter maintenance intervals in commercial and industrial applications.

Cordless Drill
Cordless Drill

Brushless DC Motors Advantages:

Compared to brushed motors, brushless motors provide a number of benefits:

  • Brushless DC motors have good linear mechanical properties, allowing for a large speed range, stepless speed control, and a wide speed range;
  • Excellent torque characteristics, good middle and low-speed torque characteristics, big beginning torque and low starting current; high overload capacity
  • Soft start and stop, good braking characteristics; original mechanical or electromagnetic brake mechanism can be kept
  • Brushless DC motors have no excitation loss when compared to AC motors, and no brush friction loss and no sparks when compared to brushed DC motors.
  • High dependability, stability, flexibility, and ease of maintenance
  • Compact dimensions, low weight, and great output
  • Bump and vibration resistance, low noise, low vibration, smooth operation, long life

Brushless Motor Disadvantages

As many advantages Brushless motors have there also are a number of drawbacks to them:

  • Cost: Brushless motors have a number of drawbacks, all of which stem from their increased design complexity. To sequence the right charge through the stator coils, BLDCs require a switching controller. This increases the cost of production, which is reflected in the higher starting cost.
  • Complication: Adding complexity increases the risk of failure. We couldn’t locate any research that compared the failure rates of brushed vs. brushless power tools, although it’s often assumed that more complicated equipment is more likely to fail.
Brushless Motor Disadvantages

The Constant Speed Electric Motor

There are several different types of constant speed motors. When choosing from a large selection of products, keep in mind the application, required functions, output, and so on. The process of selecting a motor and gearhead should begin with a thorough examination of the motor’s specifications to ensure that the motor you choose meets the application’s requirements. What you need to begin your selection is some factual and useful information the motors. The constant speed electric motor combines an induction motor with a power on activated type clutch and brake. It’s perfect for frequent start-and-stop operations. Suitable for situations where the motor is run at synchronous speed independent of load torque and the motor is started, stopped, and reversed frequently.

The Dual-Speed Motors

Dual-speed motors are a cost-effective choice for applications that only require two speeds, while also lowering the chance of failure. These motors are often constructed with an operational speed and a slower speed for easier starting. Without the need of a frequency converter, dual speed motors may push fans, pumps, hoists, and other machinery at two distinct speeds.

What Is the Difference Between Constant Speed and Double Speed Tools?

  • One main difference is the gearbox design. Constant speed tools provide maximum speed and power, but dual speed tools can be configured for two modes: fast and slow.
  • Working with a two-speed tool is more efficient. On the contrary, a tool with a constant speed provides a lot of power and is very convenient for projects that require a lot of effort.
  • A double-speed tool can be used for various types of work, but a constant-speed device has been designed for a special purpose. For example, a double-speed drill is used for drilling, impact drilling and wrapping. But an ordinary drill is only suitable for drilling operations.
  • The versatility of single-speed tools is much less than that of two-speed tools, even if the power is the same.
drill chuck close up
drill chuck

What Is Rotational Speed (RPM)?

Rotational speed motors (RPM) , in terms of an electric motor, is the number of rotations of a tool per unit of time and is measured in revolutions per minute (RPM). In fact, RPM is a unit of measure used to show the no-load speed or frequency of a power tool.

📌 The turning speed is considered an important factor depending on the type of work that we are going to carry out. Therefore, when we use an electric machine to work on hard surfaces such as concrete, we are interested in opting for more revolutions per minute.

This speed also has a direct relationship with the type of tool we use. For example, cordless drills typically offer a maximum speed of around 2000 RPM, while most corded drills typically operate at a speed of 3000 RPM.

What Is Power Tool Torque?

The force that causes an item to rotate, measured in Newton Metres (Nm), is the greatest indicator of how strong your drill or impact driver is. The greater the figure in newton metres, the more twisting force it will give.

Traditional Torque Rating Measurement Method:

1. Drilling into the rig
2. securing the chuck to a stationary spindle
3. Drill is completely operational.
4. Drill torque is measured at 0 revolutions per minute (does not measure speed)

New Power Rating Measurement Method:

1. Drilling into the rig
2. securing a chuck to a spinning spindle
3. Drill is completely operational.
4. Torque loads are becoming more prevalent.
5. Multiple data points are used to calculate drill speed and torque.

Close-up view of a drill while adjusting
drill adjusting

Power Tool Torque Settings

When driving screws into tougher materials, you’ll need to go slower and apply more torque. You can adjust the depth of your drilling without inflicting any harm if you get these parameters perfect. To achieve the greatest results while drilling holes, the tougher the material, the faster the speed.

What Is the Difference in Turning Speed and Torque?

The concept of tightening torque expresses the amount of rotating force produced by the motor of a power tool. As an example, the rotary force of a screwdriver is used to tighten screws, nuts, or anything similar. In another saying, torque, which is measured in terms of Newton meters (Nm), is the force dedicated to turning an object and is the best indicator to find out the practical power of a power tool.

💠 However, the rotational speed, as the name describes well, shows the rotational speed of an electric motor. For example, the higher the RPM of a drill, the higher the speed of the bit.

Important note: Torque and rotational speed are not only different things, but they also have a completely inverse relationship. In simple terms, when a power tool offers high torque, it will have a low turning speed, and vice versa.


When compared to brushed DC motors, what are the benefits of brushless DC motors (BLDC motors)?
Brushless DC motors (BLDC motors), which do away with brushes and commutators with mechanical contacts, are low-noise, low-maintenance, and capable of high-speed operation.

What is the brush material in a DC motor?
Metal, carbon, and metal-carbon composites are common materials for brushes. Some metal brushes use a commutator to apply precious metals like gold to a contact surface. A brush’s substance is carefully selected based on electric voltage/current as well as enonomical considerations.

What are the components of a basic motor?
An armature or rotor, a commutator, brushes, an axle, a field magnet, and some type of DC power source make up a basic motor.

What is the maximum lifespan of an electric motor?
If operated under typical operating circumstances, an electric motor can last between 15 and 20 years under test settings.

Is it better to use a DC or an AC electric motor?
Although AC motors are more powerful and require less maintenance, DC motors are more energy efficient. The use of the electric motor has an impact on whether AC or DC is chosen.

Conclusion 🧾

Considerations such as power source type, internal construction, application, and kind of motion output can all be used to classify electric motors. Aside from AC vs DC, motors can be brushed or brushless, single-phase, two-phase, or three-phase, and air-cooled or liquid-cooled.

Vacuum cleaners, dishwashers, computer printers, fax machines, video cassette recorders, machine tools, printing presses, autos, subway systems, sewage treatment facilities, and water pumping stations are all examples of electric motors’ importance in modern life. The new period, on the other hand, heralds a greater focus on detail as a result of development, law, and the need to remain competitive. As a result, systems become more complicated, and resources scale up in response. Making an expert system is unquestionably an engineering problem, and minor percentage efficiency increases can help pave the path to the optimized/green future we seek. The objective is to fine-tune and develop motor designs and control algorithms.

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