The use of Encoders in Electric Motors

Encoders are electromechanical signal generators that convert the mechanical work performed by a system into digital data to be interpreted as an electronic signal. These devices track various information such as movement, position, and speed and play a critical role in monitoring and managing systems that require precise control.

Where is Encoder Used? 

Encoders vary according to different types of applications and some examples are given below:

• Encoders are used in the manufacturing industry where precision cutting and movement operations are performed.
• Encoders are used in equipment such as cutting machines, lathes, and milling machines to ensure accurate positioning.
• Encoders, which are frequently used in PLC and automation applications, monitor and control machine movements and work integrated with automatic control systems.
• In space and observation systems, encoders are used for position tracking of systems such as telescopes and antennas.
• In precision servo operations, encoders are used to accurately control the position and speed of motors.
• Packaging machines, one of the industrial equipment, use encoders to determine the correct position and position of the products.
• In door control systems, encoders ensure safe operation by monitoring the correct position and movement of the doors.
• In milling systems and cement production stages, encoders are used to monitor the position and speed of material feeding and conveyor belts.
• Encoder price varies depending on factors such as the technology used, measurement accuracy, signal resolution, features, and brand. Encoders with higher specifications, high precision, or designed for specialized applications usually come at higher prices. However, encoders can be found in a variety of price ranges depending on the market, depending on the user's needs and budget.

These examples illustrate how encoders are used in a variety of industries and applications. Encoders can have a variety of features to meet accuracy, precision, and control requirements in different systems.

What Does Encoder Do?

What does encoder mean, it provides precise control thanks to the signal produced by the movement and ensures that the systems operate by the desired position, speed, and differentiated operating modes. If we give an example of this situation, cutting is performed at regular intervals on a conveyor belt. This cutting process must be carried out at the right time so that the products are equal and of the same length. Encoders ensure that the motor controlling the cutting process rotates at exactly the right speed, ensuring accurate and precise manufacturing without any speed or cutting time differences.

How Does an Encoder Work?

Encoders are electromechanical systems that measure mechanical movement. The sophistication of the encoder has an impact on the precision and accuracy of the measurement. Let's explain how they work by focusing on optical encoders:

• Optical encoders use a light source such as an LED. The light emitted from the LED travels towards a striped disc. This disc has a pattern with opaque lines, like on a bicycle wheel.
• As the shaft of the encoder is rotated, the LED light hits the opaque stripes on the disc and is interrupted. This interruption is detected by the photodetector unit.
• The detected interruption generates a pulse-shaped signal. If there is light, the signal is interpreted as "on"; if there is no light, the signal is interpreted as "off".
• The generated signal is then transmitted to the counter or controller and used to perform the desired function.
• In this way, optical encoders convert mechanical movement into light signals, allowing us to obtain digital data and realize control.

Figure-1 Optical Encoder logic

How to Measure Encoder?

Encoders are classified according to the number of pulses (e.g. 1024) depending on their measurement frequency and sensitivity, or according to their dimensions according to the characteristics of the place to be connected. This classification is made according to the shaft diameter for shaft encoders and according to the bore shaft diameter size for shaftless encoders. This ensures that the encoders have the correct dimensions and measurements to ensure proper installation and use.

What are Encoder Types?

Encoders are diversified using different measurement technologies. These technologies include mechanical, magnetic, optical, and resistive measurement technologies. Optical encoders are the most widely used type of measurement technology.

In addition to the technologies used, motor encoders are also diversified according to their usage and features. This diversity arises depending on factors such as mode of operation, connection type, sensor type, output signal, and position type.

Some encoder types and features are exemplified below:

Mode of operation;

Figure -1 Linear Encoder                                                Figure-2 Rotary Encoder

The way it connects;

Figure-3 Shaft Encoder                   Figure -4 Bore Shaft Encoder

According to Sensor Type;

Figure-5 Optical Encoder                         Figure -6 Magnetic Encoder

By type of position ;

• Absolute Encoder is a type of encoder that generates a constant signal for each position of the rotating shaft and performs position adjustment depending on the position. This encoder generates a predefined constant signal according to a specific position and starts to operate when energized. When the power is cut off, it remains in its position and can continue from where it left off when re-energized.
• Incremental Encoder works by generating a continuous signal according to the rotating shaft. This encoder type generates a continuous signal instead of a fixed position signal. Each time it stops, it accepts its position as zero and starts at zero when it is re-energized. In other words, it returns to the starting point at the moment of each energization and measures by continuously increasing the position. 

Encoder Use in Electric Motors

Encoders are used extensively in various types of electric motors. In many types of motors such as servo motors, asynchronous motors, synchronous motors, Encoder DC motors, and generators, encoders are frequently used depending on the shaft. Especially in production systems where asynchronous motors are used, it is very common to use encoders for speed control, operating speed adjustment, and control of applications to which asynchronous motors are connected.

Encoders offer a variety of choices depending on harsh operating conditions, measurement frequency, shaft diameter, and encoder dimensions. Selecting the right encoder for each application is important to ensure correct operation and reliability. Encoders interact with motor control systems by accurately sensing the rotational speed and position of the motor.

Encoders provide feedback to motor control systems, providing the ability to provide precise control and positioning. In this way, they can provide the desired speed, position, and movement characteristics of the motors. Encoders also can remember the position of the motors after a power failure. 

Things to Consider When Selecting Encoder

When selecting an encoder, it is important to pay attention to the following criteria:

• Pulse interval: The number of pulses determines the measurement accuracy of the encoder. The higher the number of pulses, the higher the sensitivity.
• Ambient temperature and operating conditions (IP class): The temperature range and operating conditions of the environment where the encoder will be used must be taken into consideration. Factors such as dust, humidity, oil, and vibration affect the protection level specified by the IP class.
• Bore shaft or shaft: The appropriate encoder should be selected according to whether the shaft in the system to which the encoder will be connected is shaft or hollow. While shaft encoders are classified according to shaft diameter, hollow encoders are classified according to hole diameter.
• Determining the shaft diameter of the encoder or the hole diameter if it is a hollow encoder: For the encoder to fit correctly, the diameter of the shaft to be used or the hole diameter of the hole encoder should be determined correctly and the selection should be made accordingly.
• Clarification of the encoder's construction material properties: Depending on the intended use and operating conditions of the encoder, the material of construction (e.g. metal, plastic) and durability characteristics should be clarified.

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