The most important difference between servo motor and DC motor is that a servo motor is used for positioning systems, whereas a DC motor is used for driving mechanical loads.
Electric Motors are defined as rotatory electric machines or devices that transform electrical energy into mechanical energy.
Depending upon the construction, principle of operation, power supply, and several other factors, electric motors are of numerous types. Some of them namely – synchronous AC motors, asynchronous AC motors, DC motors, induction motors, servo motors, etc.
This article will mainly focus on two types of electric motors viz. Servo motor and DC motor. This article will begin with a short introduction to the two types of motors, followed by highlighting the key differences between them.
What is Servo Motor?
Servo Motor functions as a controlled feedback system that operates at fixed intervals. It is similar to a DC motor, besides the fact that it rotates at particular angular positions ranging from 0 to 180 degrees in some servo motors, while from 0 to 360 degrees in some others depending on the type of application it is used for.
The angular positions of the servo motor are set using a microcontroller device, wherein the three wires of the servo motor (i.e., PWM, ground, and power) are connected to specific pins of the microcontroller device. A pulse width modulated signal (PWM) is passed to the PWM pin or control pin of the servo motor to control the angular velocity of the motor depending on the turning angle required.
Depending on the power supplied to the servo motor, it can be of the following two types:
- DC servo motor
- AC servo motor
DC Servo Motors requiring direct electric current for operation, are used for small-scale applications such as door locks, robotic arms, surveillance camera systems, etc. While AC Servo Motors are used in large-scale industrial applications requiring to drive or operate heavy AC-powered mechanical loads.
What is DC Motor?
A DC Motor is a kind of electric motor that operates by the conversion of electrical energy in the form of direct electric current, into mechanical energy in the form of shaft rotation.
Based on the presence of carbon brush, DC motors are of the following two types:
- Brushed DC motor
- Brushless DC motor
The DC motor is composed of the stator and rotor. The stator is responsible for generating a magnetic field, while the rotor acts as the armature of the DC motor. The other two vital components of a DC motor are the carbon brushes and the commutator segments. The carbon brushes are responsible for maintaining the electrical connection between the armature and the commutator segments. The commutator segments present the edges of the armature windings.
The DC motor operates on the principle of Lorentz Law. The principle of operation of the DC motor involves the interaction of the magnetic field of the stator and rotor, resulting in the generation of motor torque. This generation of torque, results in the rotation of the DC rotor, producing mechanical energy as the output of the shaft. DC motors of varied sizes find their applications in numerous electronic devices such as toys, cranes, power tools, elevators, etc.
Difference between Servo Motor and DC Motor
The following table highlights the major differences between the servo motor and DC motor.
| Parameter | Servo Motor | DC Motor |
| Definition | A Servo motor is a rotational actuator that rotates at specified angular positions and velocities. | DC motor is a machine that runs on direct electric current to generate mechanical energy from electrical energy. |
| Types of motor | Servo motors can be of two main types: AC servo motors and DC servo motors. | DC motors can be broadly classified into 2 main types, viz. brushed and brushless DC motors. |
| Working principle | The Servo motor works on the principle of pulse width modulation (PWM). | DC motor operates on the principle of Lorentz Law. |
| Rate of rotation | The servo motor rotates at an average speed ranging between 1000 and 6000 RPM. | The DC motor has a variable moderate speed based on the kind of DC motor. |
| Type of movement | The motion of servo motors is based on a fixed controlled interval. | The motion of DC motors is rather continuous. |
| Dependability | Servo motors provide highly accurate output. | DC motors provide intermediate accuracy on the output generated. |
| Maintenance | Due to the absence of brushes, the stepper motors do not require frequent maintenance or upgrades. | Due to the presence of brushes, DC motors require frequent maintenance or upgrades to function properly. |
| Performance | The efficacy of servo motors is comparatively much higher as compared to DC motors. | The efficacy of DC motors is relatively lower. |
| Continuous / non-continuous use | Stepper motors operate at fixed intervals with programmed gaps, i.e., in a non-continuous manner. | DC motors are used to operate for longer durations with minimum or no gaps, i.e., in a continuous manner. |
| Motor speed control | To control the speed of the servo motors, complex calculations, datasheets, and formulas are required. But it can be precisely controlled as per demand. | To control the speed of the DC motor, reversing the ground and power wires of the motor would reverse its direction of rotation. Moreover, to change the rate at which it rotates, the voltage level has to be varied. |
| Affordability | Servo motors are comparatively costlier than DC motors | DC motors are easily affordable as compared to servo motors. |
| Applications | Servo motors find their applications in the angular control of machines such as doors, toys, robotic arms, printers, etc. | DC motors find their applications in the operation of several electronic devices such as several home appliances such as mixers, microwaves, toys, etc. |
Conclusion
In conclusion, both DC motors and servo motors are extensively used in a wide variety of industries as well as simple applications. This article provides insight into the key differences between DC and servo motors. One of the most significant differences between them is that, as DC motors are cost-effective, they are used in a wide range of industrial applications to operate bulky types of machinery. But on the other hand, servo motors find their small-scale applications in designing toys, door locks, movable robotic parts, etc.
