What Are Motor Speed Controls?
Motor speed controls are devices integrated into motors to adjust their rotational speed. These controls use speed measurement sensors attached to the motor’s drive, allowing for feedback control based on the sensor’s readings. Alternating current is commonly used as the power source for these systems.
Applications of Motor Speed Controls
Motor speed controls are essential in production plants and equipment requiring precise motor operations. They are employed in:
- Driving units of positioning equipment in semiconductor and electronic component manufacturing processes.
- Power sources for yarn and wire winding operations.
- Reducing load when stopping conveyors and other machinery.
Selection considerations include the variable speed range, speed control accuracy, lifespan, power consumption, size, and resilience against heat, dust, and vibration.
Operating Principle of Motor Speed Controls
The rotation speed control circuit computes the necessary rotation based on signals from an external speed setting device and the motor speed signal from the sensor. The electrical signal control circuit then determines the voltage to supply to the motor, adjusting the power provided from an external supply based on this calculation.
Structure of Motor Speed Controls
Motor speed controls consist of an operating section, including the motor and a rotation speed sensor, and a control section, comprising circuits for speed and electrical signal management. The sensor, often a rate generator, outputs an AC voltage proportional to motor speed, facilitating feedback to the control section. The motor operates on the same principles as typical AC motors, generating rotational force from an induced current.
Additional Information on Motor Speed Controls
1. Rotational Speed — Torque Characteristics
The relationship between rotational speed and torque can be visualized on a graph, identifying the continuous operation area and limited operating range. Ensuring operation within these parameters guarantees efficient performance without overheating.
2. Comparison with Other Motors
Motor speed controls differ from inverter-driven motors, which can control both speed and torque, and from brushless motors, which are easier to control by inputting the rotation speed to the motor driver. When comparing functionality, inverters offer more features, but motor speed controls are more cost-effective and user-friendly for controlling smaller motors.