DC motors are a prevalent form of electric motor that converts electrical energy into mechanical energy. The constructions of a DC motor include a stator, rotor, commutator, and brushes. When an electric current flows to the motor, a magnetic field interacts with the rotor’s magnetic field, causing the rotor to rotate. In this post, we will examine in depth the working principle of DC motors.
what is a DC motor
A DC motor can convert electrical energy into mechanical energy. Direct-current (DC) motors convert electrical energy into mechanical rotation using direct current.
DC motors use magnetic fields generated by electrical currents to power the rotation of a rotor that is fixed within the output shaft. The electrical input and the motor’s design determine the output torque and speed. So who invented this usage device?
Who invented the DC motor
As with all significant innovations, numerous individuals contributed to creating similar mechanisms.
Thomas Davenport is widely celebrated in the United States as the inventor of the first electric simple motor. In 1834, Moritz Jacobi presented three times more potent motors than Davenport would later patent. In 1835, Sibrandus Stratingh and Christopher Becker were the first to demonstrate an electric motor’s practical application by driving a miniature model car using a miniature direct current motor.
Frank Julian Sprague invented the first practical DC motor in 1886, which led to the development of the first motor-powered trolley system in 1887 and the first electric elevator in 1892. Sprague’s DC motor was a tremendously important innovation, spawning various applications that would transform industry and manufacturing.
With the growth of the functions of DC motors, do you know nowadays where this device is used?
List some examples of applications in which DC motors are still used are
Applications of DC Motors
Because of the wide range of available DC motor varieties, there are numerous applications for DC motors. Although each form has its advantages, there are a variety of applications for DC motors. Small DC motors are utilized in various instruments, hobbies, and residential appliances. In retail, DC motor applications include conveyors and turntables, whereas industrial applications for large DC motors include braking and reversing. Here are some additional applications for DC motors:
DC generators for fans
DC motors use magnetic fields to convert electrical energy into mechanical energy. By employing brushless motors, DC motor ceiling fans can be powered by conventional domestic AC power.
DC actuators for pumping systems
DC motor pumps, like ceiling fan motors, have benefited from developing low-cost brushless DC motors, which are significantly simpler to maintain on a large industrial scale.
DC generators used in toys
DC motors for toys are a popular option for manufacturers and lovers, and these “toy motors” are frequently used in remote control vehicles and model trains for children with electric motors and controllers. DC motors can be used for devices that require various rates and movement types.
DC generators in electric bicycles
Although various types of DC motors are used in electric vehicles, DC motors are the most common due to their energy efficiency and durability. Many hobbyists and model car manufacturers favor large DC motors due to their greater starting torque, especially series-wound motors, and their variable velocities with voltage input.
DC actuators used by robots
Many enthusiasts and engineers define robots as any electromechanical device designed to accomplish a specified mission. A DC motor for robots is used to ‘actuate’ something, such as tracks, limbs, or cameras, and this motor is especially popular for many reasons.
DC generators for cycles
Popular electric cycles do not require a license if their maximal assisted speed is below 20 miles per hour. Typically, brushless DC motors are used in electric motorcycles to achieve the required levels of force and torque. Electric bicycles are equipped with a compact DC motor hung in the hub of the rear or front tire or the center of the frame and connected to the pedal sprocket.
How Does A DC Motor Work Physics
A DC motor is an electromechanical device that converts direct current electrical energy into motion. It’s a rotary device with applications ranging from industrial machinery to consumer electronics.
DC motors can range in size and power from small motors found in toys and home appliances to large mechanisms used to power vehicles, draw elevators and hoists, and operate steel rolling mills. How do DC generators operate?
The two essential components of DC motors are the stator and the armature. The stator is the component of a motor that remains stationary while the armature rotates. In a DC motor, the armature is rotated by a magnetic field produced by the stator.
A DC motor operates using a stationary arrangement of magnets in its stator. This creates an electromagnetic field when a coil with an electric current is placed in the center. To further enhance the magnetic field, one or more insulated wire windings are wound around the core of the motor. As a result, this increases the magnetic field’s concentration and performance improvements can be realized.
A commutator (a rotary electrical switch), which supplies the windings with an electrical current, connects with the windings of insulated wire. The commutator enables the sequential energization of each armature coil, producing a constant torque.
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When the coils are sequentially switched on and off, a rotating magnetic field is produced that has connections with the different magnetic fields of the stator’s stationary magnets to generate torque, causing the stator to rotate. These fundamental operating principles of DC motors enable them to convert the direct current’s electrical energy into mechanical energy that can be used for propulsion.
Types Of DC Motors
This guide has thus far provided an overview of how DC motors function, the history of these mechanisms, and their appearance. There are wide distinct varieties of DC motors, each with advantages and disadvantages, although the underlying principles are the same.
This section examines the four primary varieties of DC motors: brushless, brushed, shunt, and series.
DC brushless motors
Brushless DC motors, also called electronically commutated or synchronous DC motors, differ from brushed DC motors due to the development of solid-state electronics.
If you see on the brushless motor diagram, brushless DC motors are distinguished from other types by the absence of a commutator, which is substituted by an electronic servomechanism that can detect and modify the rotor’s angle.
The brushless DC motor has numerous benefits. Commutators utilize flexible contacts known as ‘brushes’ that degrade over time. Therefore, a brushless DC motor is more durable and safer than its conventional counterpart.
All electric motors generate torque by switching the polarity of rotating magnets on the rotor and stationary magnets on the stator. At least one of these magnets is an electromagnet of a helix of wire wrapped around an iron core.
DC motors operate on the principle of changing magnetic fields, where the direction of the DC must be reversed every 180° rotation of the armature to generate torque in a single direction. The wire windings of a DC motor create an alternating north and south pole magnetic field as they rotate, which is necessary for the motor to function properly.
Brushed motors use a commutator to control the current; brushless DC motors, however, utilize an electronic sensor that determines the angle of the rotor. Electrical semiconductor switches regulate and alter the direction of the current with meticulous timing to create torque in one particular direction.
Brushed DC engines
The brushed DC motor is the first DC motor ever created, dating back to Sprague’s design. As discussed in this guide, the traditional brushed motor incorporates a commutator, reversing the current every half cycle and generating unidirectional torque.
While brushed DC motors are still widely used for electrical propulsion, paper machines, cranes, and steel rolling mills, the more efficient brushless variant has replaced many in recent years.
This guide explains that brushed DC motors use flexible contacts called “brushes” to ensure the motor rotates in a single direction. The pace of brushed motors can be altered by adjusting the operating voltage or magnetic field strength.
Several types of brushed DC motors vary based on the armature connection, as will be discussed in the following sections.
Shunt DC engines
A DC shunt motor is a brushed motor in which the field windings and armature are connected in parallel. Due to the parallel windings, shunt wound DC motors have a reduced current.
A shunt motor is utilized for conveyor belts, mixers, and hoists requiring constant torque and where speed does not substantially affect the burden.
The unique field windings of a shunt motor make it a good choice for applications requiring constant torque. The Parvalux Shunt Brushed DC Motor depicted on the left has constant speed characteristics, with the minimal difference between no-load and full-load speed being the primary advantage of this type of motor.
Series DC motors
In this guide, series wound DC motors are the ultimate type of brushed motors. The primary distinction between this type and previously discussed shunt motors is that the field windings are connected in series.
This indicates that the entire armature current is transferred to the field winding, resulting in significantly higher velocities.
Due to the inability to adjust the supply voltage, series DC motors cannot modulate their speed particularly well.
While this may be an issue for some applications, it makes them ideal for duties requiring a high starting torque, such as power tools and stitching machines.
The specific characteristics of DC series motors serve a distinct and purposeful function. The Faulhaber Brushed DC Geared motor is an excellent example of the advantages of series wound motors, as it has an appliance-friendly high starting torque.
Difference between AC and DC
Regarding AC and DC motors, there are several key differences to note. The most evident is the type of current used – alternating current (AC) or direct current (DC). DC motors are great for speed control and have a wide range of output speeds. So how does an AC motor work?
Conversely, AC motors tend to have higher power outputs and be more efficient in their electrical usage. Additionally, AC motors can be single- or three-phase, while DC motors are always single-phase.
Through the interaction of magnetic fields, DC motors convert electrical energy to mechanical energy. They are used in various applications, including electric vehicles, industrial apparatus, and home appliances. Understanding the operation of DC motors is essential for designing, operating, and maintaining these indispensable devices.