Open-loop control (also known as scalar control or Volts/Hz control) is a popular motor control technique that you can use to run any AC motor. This is a simple technique that does not need any feedback from the motor.
A motor open loop is a control system used to control the speed or position of the motor, open loop system is also known as a "no feedback system". In an open-loop system, control inputs such as voltage and current are not compared to the output required for speed or position, i.e., the control inputs are not affected by the output, and the system does not adjust the control inputs based on feedback from the motor. In a clock, for example, there is no device in the clock to observe whether its time is accurate, and it does not actively adjust its time, so the clock is an open-loop system.
Advantages and disadvantages of open-loop systems
- One of the main advantages of an open-loop system for motors is its relative simplicity and ease of implementation. The control input is determined by a set of instructions or a fixed algorithm and does not require any feedback from the motor.
- It is also the nature of an open-loop system that causes it to not be very accurate or precise. The system does not adjust the actual control input based on feedback from the motor, which can lead to output errors, such as changes in speed or position, that can easily make the overall operation poor.
Despite these drawbacks, motor open-loop systems are widely used in many applications. They are often used in simple machines or systems where accuracy and precision are not critical. They are also used in applications where cost is a major consideration, as open-loop systems are typically less expensive to implement than closed-loop systems.
In summary, an open-loop motor system is a control system used to control the speed or position of a motor. It is relatively simple and easy to implement, but not as accurate and precise as a closed-loop system, so it is mostly used in simple machines or systems that do not require high accuracy and precision.