CONTROL OF ASYNCHRONOUS AC ELECTRIC MOTOR ACCORDING TO THE PRINCIPLE OF CONSTANT V/F AND CONVENTIONAL PWM CONTROL

Abstract

The principle of operation of any automatic control system is to detect deviations of regulated values from set values and to form influences on the control process to eliminate these deviations. Often, a variable value whose value must be maintained constantly or changed according to the desired law is called a controlled value (coordinate). It is customary to call the required value of the regulated value (coordinate) set, and the actual value - current. The difference between the setpoint and the actual value is a deviation or error signal. A set of devices that affect the object of control, maintaining the current value of the controlled quantity (coordinate) equal to the given one, is called an automatic regulator or a dynamic system. The influence of the regulator on the object with the aim of bringing the current value of the controlled value closer to the set value (or adding the desired properties to the closed system) is called the control influence, and the set of devices and physical environments through which the control influence acts on the controlled value is called the control channel. The control process carried out by the regulator manifests itself in a change in the set value of the regulated quantity or a deviation of at least one of the unregulated quantities that affect the regulated one through feedback circuits. A change in the set value of an adjustable quantity is called a controlling or internal setting influence, and a change in unregulated quantities is called an external disturbance. The principle of deviation control is to compare the set value of the regulated value (setting) with its current value. In this case, the error signal Δ is used to create such a regulatory influence on the control object that this error, regardless of the reasons that caused it, does not go beyond the permissible values. In order to protect the environment and reduce the effect of greenhouse gas emissions, regulations are being introduced all over the world that require manufacturers of household electrical equipment and industrial enterprises to produce products that use electricity more economically. Most often, this can be achieved by effectively controlling the speed of the electric motor. This is the reason why consumer appliance developers and semiconductor suppliers are now interested in developing low-cost and economical adjustable actuators.