Electrical Drive Block Diagram, Example, Applications, Types

Electric Drive is a system with a combination of electric motors and their speed or motion-controlling circuits. The controlling of the speed of an electric motor with discrete or variable signals brings the concept of an electrical drive system. The main function of an electrical system is to control the speed of the motor as accurately and precisely as much as possible. Also, the electrical drive system takes care of the safety and protection of the motor. Nowadays, electrical derive system uses electronic circuitry and allows digital inputs through software, which makes the electric drive system more powerful, more efficient, and more accurate. The electrical drive system is built with different electronic circuits consisting of electronic semiconductor devices such as MOSFET, IGBTs, etc.

Electrical Drive Block Diagram

Here, you can see a typical block diagram of an electrical drive system.

The main parts of an electrical drive system are explained below,

Input Source Power Supply

The type of input power supply of an electric drive system depends upon its design and requirement. It may need AC or DC power supply. The input power source of an electric drive system has a rectifier circuit, filter circuit, and regulator circuit. The power processing unit(PPU) or power modulator generally takes the DC supply only even if the main put source is AC. The main function of the input power circuit of an electrical drive system is to provide power to the power modulator and keep regulating the voltage means the output of the power circuit always be constant even the power fluctuation or voltage changes in the input of the system. It not only provides power to the modulator but also provides power to other parts of the drive system such as the control unit, sensing unit(if required), etc.

Power Processing Unit(PPU) or Power Modulator

The power processing unit process the main power flow from the input source to the motor according to the control signal provided by the control unit. The rectification process, inversion process, and frequency-varying process happen in the power modulator. For the DC motor control, the modulator first converts the input AC into pulsed DC signals to provide the motor. For AC motor control, if the input supply is DC then it converts into a variable frequency AC supply to provide the motor. So, for controlling the DC motor Pulse Width Modulation(PWM) technique is used, and to control the AC motor variable frequency technique is used.

Electric Motor

The electric motor is the actual device or machine that does the physical work and works under the controlled power from the modulator. Different types of motors require different electrical drive systems. Generally, all types of the motor such as AC motors, DC motors, Universal motors, and Robotic Motors can be operated under the drive system.

Sensing Unit

The sensing unit is connected to different types of sensors. It senses and measures the speed, torque, and direction of the motor rotation. It generates the feedback signal and provides it to the control unit. The speed Sensor measures the rotational speed of the motor shaft and provides feedback to the control system. Similarly, the Position Sensor determines the position of a moving part, typically the rotor or load, and provides positional feedback to the control system. The electric drive system also uses the current which is a very vital part of the system. It measures the electric current flowing through the motor windings or power electronic components. Current sensors are essential for monitoring motor performance, detecting overloads or faults, and implementing current control strategies.

Control Unit

The control unit takes the both feedback signal from the sensing unit and the reference signal from the input device and generates a controlled signal to provide it to the power modulator. The Control unit is built with electronic circuits, programming devices, etc. The control unit processes the sensor data, makes decisions based on the program control logic, and generates appropriate control signals to drive the power electronics and actuate the motor.

Examples of Electric Drive Systems

• VFD or Variable Frequency Drive is an example of an electrical drive system.
• Screw Compressors, servo mechanism
• Conveyors, Elevator drives are also examples of electric drives.

Types of Electric Drive Systems

1. According to the nature of the power supply Electric Drive two types - AC Drive and DC Drive
2. According to the nature of the speed, there are also two types - Stable Speed Drive and Variable Speed Drive
3. Based on the number of motors used for the applications - Single Motor Drive, MultiMotor Drive

Applications of Electric Drive System

1. Electric Drive is used in traction systems.
2. Electrical drive used in industrial motor controls, pump controls, lift control, etc.
3. An electric drive system is used in transportation systems such as electric vehicles.

Read Also: 

• Difference between Motor Driver and Motor Controller with Example
• Actual Difference between Servo Motor and Stepper Motor
• [Explained] Motor Circuit Protection System and Devices
• Double Motor Control with Selective Switch Connection
• Actual Difference Between Synchronous Motor and Induction Motor

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