Design Of Alternating Current Phase Selector Switch Controller On Single Chip Microcomputer

Nowadays, many of the plant equipment, for example, large machine tools^fully automated production lines and so on, are driven by the large electric motor.However,motors are inductive load, Due to the special nature of the inductive load, power factor can be decreased when the motor are operating。 This phenomenon will increase the power consumption of the grid, the proportion of active power,which is transported in the grid,is reduced.In order to improve the power factor,the method of parallel capacitor banks is more commonly used. It have been widely applied in many fields。 But random switching compensation capacitor would cause inrush current and over-voltage transient phenomena.For this reason,people use various methods to suppress these transient,phenomena.Studies have shown that using simultaneous switching capacitor banks to achieve zero-crossing switching is the best way to suppress these transient process.Their development process can be divided into AC contactors, thyristor switch, combination switch.However, because these types of switches have their own shortcomings and deficiencies,these types of switches has not been widely used in industry.Today, with the development of industrial, microcontroller as the core of the phase selection switch has been widely applied.Switch controller,which is described in this paper,is to PIC18C452as the core, and designed voltage and current zero signal acquisition and processing circuit,voltage and current fault signal acquisition and processing circuit,relay driver circuit,command input,display and fault alarm circuit.Switching controller design includes hardware design and software design.Hardware design includes the design of power supply circuit,voltage current zero signal acquisition and processing circuit design,voltage and current fault detection signal acquisition and processing circuit design,relay driver circuit design,command input circuit design,display circuit design,failure alarm circuit design.Software design,including the main program design,relay driver program design,the zero point of voltage and current acquisition program design,fault detection program design,automatic error compensation program design,relay performance testing program design,the program design of entering instructions,LCD program design,Alarm program design,and so on.That advantage of the switching controller compared to other similar products function is automatic detection relay performance,automatic detection of Zero point switching error and Automatic compensation function.