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What is the main function of AC drive?



What is the main function of AC drive

An AC drive, sometimes referred to as an adjustable-frequency drive or variable-frequency drive, is primarily used to regulate the speed and torque of an AC electric motor. To increase energy economy and enable precise control over motor operations, AC drives are widely employed in a variety of industries and applications.

An AC drive serves the following primary purposes:

1. Speed Control:

The motor’s rotational speed can be controlled precisely with AC drives. The drive has a wide range of control over the speed of the motor by modifying the frequency and voltage provided to it. Applications requiring changing speeds, such conveyor systems, pumps, fans, and machine tools, can benefit greatly from this capability.

  • Variable Speed Operation: The motor can work at various speeds depending on the application’s needs thanks to AC drives. This adaptability is especially useful in procedures that call for precise motor speed control or work with fluctuating loads. For instance, conveyor systems allow for speed adjustments to match production rates, which optimises material handling processes.

Check: Allen Bradley PowerFlex 4M AC drives

2. Torque Control:

Accurate control over the motor’s output torque is provided by AC drives. This feature enables the motor to operate smoothly and effectively, ensuring that it delivers the necessary amount of torque depending on the load circumstances. It makes it possible for applications that require different torque levels, such cranes, elevators, and escalators, to function properly.

  • Precise Torque Regulation: AC drives allow precise control over the motor’s torque output. This feature is especially important in applications where maintaining a consistent and accurate torque level is critical. For instance, in robotics or CNC machines, precise torque control ensures accurate positioning, machining, and handling of objects.
  • Load Adaptation: Depending on the load conditions, various applications call for different amounts of torque. The torque output of the motor can be modified by AC drives to adapt to shifting load needs. The drive provides optimum performance and efficiency by adjusting the torque in real-time, avoiding problems like stalling, overloading, or excessive power consumption.

3. Energy Efficiency:

AC drives play a key role in improving energy efficiency. The drive reduces energy usage by altering the motor’s speed and torque to correspond with the particular load needs. It does away with the requirement for mechanical throttling mechanisms, such as dampers or valves, that would otherwise be used to release extra energy. Energy savings from AC drives result in lower running costs and a more environmentally friendly method of motor control.

  • Variable Speed Operation: AC drives are essential for increasing energy efficiency. The drive lowers energy consumption by adjusting the motor’s speed and torque to suit the demands of the specific load. The need for mechanical throttling devices, like dampers or valves, that would often be utilised to release surplus energy, is eliminated. Lower operating expenses and a more ecologically friendly technique of motor control are the results of energy savings from AC drives.

4. Soft Start and Stop:

Instead of abrupt starts and stops, Rockwell Automation AC drives have features for soft starting and stopping that gently ramp up or down the motor’s speed. By lowering mechanical stress, this feature increases the lifespan of the motor and any linked equipment. Soft starting and stopping reduce voltage drops and power surges, resulting in a more steady and dependable functioning.

  • Controlled Deceleration: Instead of a sudden halt, a soft stop enables a gradual reduction in the motor’s speed. The motor and the driven equipment experience less mechanical stress as a result of this controlled deceleration. In applications like conveyors or material handling systems, it reduces the danger of damage or material loss by avoiding abrupt changes in load distribution.
  • Energy Recovery: Regenerative braking is a feature available on some AC drives at gentle stops. Regenerative braking enables the drive to transform the excess energy produced by the motor during deceleration into useable power rather than dissipating it as heat. Energy can be saved by using this energy in other ways or by reusing it in the power supply system.

5. Motor Protection:

Comprehensive motor protection measures are provided by AC drives. These include of thermal protection, short circuit detection, voltage and current monitoring, and overload protection. AC drives assist in preventing damage to the motor and ensuring its longevity by continuously monitoring motor performance and responding to anomalies.

  • Overload Protection: When the current flowing through the motor exceeds the predetermined limitations, AC drives can detect it. The drive can react to an overload condition by lowering the motor’s torque or by turning on an alarm or trip signal. The longevity of the motor is increased by overload protection, which keeps it from overheating.


  • Voltage and Current Monitoring: The voltage and current delivered to the motor are continuously monitored by AC drives. Deviations from the predicted values can be a sign of problems such voltage swings, phase imbalances, or excessive current use. The drive can react by changing how the motor operates or by sending out signals or alarms, enabling quick response to the underlying issue.

6. Control and Automation Integration:

Systems for automation and control can readily integrate AC drives. They can interact with other systems and devices via a variety of communication protocols, making it possible for them to be seamlessly integrated into industrial processes. Through this integration, remote monitoring, enhanced control techniques, and diagnostics are made possible, increasing system productivity and efficiency.

AC drives are essential for regulating the torque, speed, and energy efficiency of AC electric motors. They are crucial components in a variety of industrial applications because of their capabilities for precise motor control, energy conservation, motor protection, and smooth interaction with control and automation systems.

Asteam Techno Solutions Pvt. Ltd. has boasts over 10 years of experience in the industrial sector, founded in India and then became one of the best industrial automation parts supplier in India as well as globally We provide automation solutions with reputed brands including Allen Bradley, Mitsubishi, Phoenix Contact, Siemens, Schneider, Moxa, VIPA and more.

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