Summary:
Introduce the design and implementation of PSOC 3-based phase shift controller based on CYPRESS products. This design uses PSOC technology, uses CapSense as the input of the control signal, and performs digital phase modulation through PSOC to achieve power adjustment. And provide key input signals to meet different application requirements of users.
introduction:
Power adjustment in the industrial field generally uses a thyristor phase shift control method to control the output power of the power supply to the load by changing the initial phase (conduction angle) of the alternating current. This type of circuit uses potentiometers, so it is inevitable that there are potentiometer defects: mechanical wear, friction noise, and the like. This design uses PSOC technology, uses PSOC CapSense and buttons as input of control signals, digital phase modulation through PSOC, avoiding the defects of potentiometer adjustment.
PSOC Brief
PSoC is a programmable system-on-chip chip produced by Cypress Semiconductor. It is mainly composed of 8-bit microprocessor, programmable analog module and digital module, plus programmable constant current source (IDAC). I2C, Flash, SRAM and other peripheral peripheral modules, as shown in Figure 1.
Figure 1 PSoC functional block diagram
Therefore, in addition to the functions of a general MCU, PSoC can flexibly implement the analog and digital peripheral functions required for embedded systems through programmable analog and digital modules. In order to facilitate the simple and fast design of analog digital peripheral functions, Cypress builds a large number of user modules based on programmable digital analog modules, such as programmable operational amplifiers, comparators, 6 to 14-bit analog-to-digital and digital-to-analog converters. , filter, 8/16 / 24 / 32-bit timer / counter, pulse width modulator, touch sensing and other modules. These user modules configure the internal registers of the PSoC, the internal connections between the digital and analog modules, and the underlying API (ApplicaTIon Program Interface) functions have been designed. When the user needs a digital analog peripheral function, it is only necessary to simply call the corresponding user module.
1, system principle
The alternating current and the PSOC are isolated by photoelectric coupling, and the zero-crossing detection signal of the alternating current is sent to the PSOC through the photoelectric coupling, and the interrupt mode is used to realize the synchronization of each cycle of the alternating current, and the initial phase is determined by using the PSOC internal timer according to the zero-crossing signal. The control trigger pulse is given to complete the control of the output AC phase to achieve power adjustment. Information such as the phase shifting angle is displayed by the Nokia 5110 LCD. Figure 1 shows the main circuit structure.
Figure 1. Block diagram of the main circuit
2, the program design
2.1 Scheme 1
An ASIC using an AC control system, which is manufactured by a CMOS process and is controlled by an external AC pulse. A variety of control methods are provided to meet different application requirements of the user, and the phase shift angle is 0 to 180 degrees. However, the use of integrated chips increases the cost of external components, is easy to damage, and has low scalability.
2.2 Scheme 2
The program controls the phase modulation, detects the zero-crossing point of the alternating current through the CPU peripheral detection circuit, and gives an accurate synchronous trigger pulse after the CPU processing to adjust the initial phase of the alternating current. The adjustment is flexible, the precision is high, and the closed loop control is easy to implement, and the expansion is strong.
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