Control system of AC (alternate current) motor

Abstract

The invention discloses a control system of an AC motor. The control system of the AC motor comprises a power conversion module, an overheating and overcurrent protection switch, a zero-passage signal detecting module, a relay control module, a silicon-controlled module and a master control module. The master control module firstly switches on the relay control module at a power supply zero point, and due to the fact that no voltage exists between both ends of a relay in the relay control module at the moment, the relay can avoid sparking; the master control module can perform time delay treatment when detecting the power supply zero point to switch on the silicon-controlled module and to start the motor; if the motor needs to be stopped, the master control module can firstly control the silicon-controlled module to stop working to cut off the live wire circuit of the motor, and then stop the working of the relay control module, at the moment, high voltages at both ends of the relay can be cut off, and meanwhile, sparking during the cut-off moment can also be avoided; the relay control module and the silicon-controlled control module together controls the starting operation of the motor to avoid spurious triggering.

Description

technical field [0001] The invention relates to motor control technology, in particular to a control system of an AC motor. Background technique [0002] AC motor is a machine used to convert mechanical energy and AC electrical energy. Currently, AC motors are widely used in the market, and are used in some stirring appliances (such as food processors) and some electric tools. [0003] The control methods of the AC motor include: 1. The power supply circuit of the motor is controlled by a single thyristor, and the voltage supplied to the motor is adjusted and controlled; 2. The power supply circuit of the motor is controlled by a single relay, and the motor current is cut off and supplied. [0004] However, there are some shortcomings in the above-mentioned motor control technology: the first one is single-circuit thyristor control, which is easily affected by the interference of the power grid and causes false triggering, so that the motor malfunctions in an abnormal state ...

AI Technical Summary

Problems solved by technology

[0004] However, there are some shortcomings in the above-mentioned motor control technology: the first one is single-circuit thyristor control, which is easily affected by the interference of the power grid and causes false triggering, so that the motor malfunctions in an abnormal state and causes harm to people; the second one is Single-way relay control, in the process of controlling high-power motors, it is easy to cause "ignition" phenomenon at the moment of starting and closing of electrical appliances, which may cause fire in serious cases, cause economic losses to consumers, and even threaten human safety

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