How to apply digital intelligent control technology of induction heating equipment?
With the improvement of the automatic control degree and reliability requirements of induction heating equipment, the development trend of induction heating equipment control technology is bound to develop from analog control to digital intelligent control direction, and it is also one of the important characteristics to represent modern induction heating equipment.
The control system of traditional induction heating equipment is constructed by analog control devices, although it has the advantages of low cost, fine linear regulation, no programming, good anti-interference performance, etc. However, its fatal disadvantage is that it is not suitable for the digital intelligence requirement of remote control and communication function. Moreover, components are easy to age, working point with temperature and time drift, solder joints, contacts caused more reliability decline, hardware parameters inconvenient to modify, poor flexibility.
The induction heating equipment adopts digital control technology, which can overcome the above defects of analog control. The advantages of digital control are (1) easy to realize external communication and remote control;(2) High degree of automation, flexible control; High integration and reliability;(4) easy to standardize, production and manufacturing convenient; The system is easy to upgrade, as long as the corresponding control algorithm can be modified, there is no need to simulate the control of the hardware circuit need to make great changes and modifications.
At present, with the emergence of high performance and cheap digital control chips, the necessity and inevitability of applying digital control technology to induction heating equipment are beyond doubt. For example, the cost-effective and powerful 8-bit AVR microprocessor chip AT Mega 8, with 32-bit digital processor chip TMS320F 2812 and other digital integrated chips, has been used for data acquisition, mathematical operation, analysis, and processing in the control system of induction heating equipment. They all have a complete set of programming and system development tools, especially in the if induction heating furnace digital frequency PLL, digital pulse width modulation D PWM, servo motor motion control, all kinds of fault protection processing, digital automatic control display great advantages.
The main functions and features of these two digital integrated chips are briefly introduced as follows:
1) a microprocessor AT mega 8 is a powerful microcontroller, maximum 16 MHZ clock frequency, 8 roads 10 bit ADC, two programmable UART serial universal asynchronous communication interface, a serial can work AT host/SPI from machine model of the interface, one has the function of frequency division, comparison and capture the 16-bit timer/counter, two independent preassigned eight frequency counter timer/counter, three-channel PWM signal, 23 programmable interfaces, 32 general purpose working registers.
2)TMS320F 2812 is a 32-bit fixed-point digital signal processor, which has not only digital signal processing capability but also powerful event management capability and embedded control capability. The maximum clock frequency is 150MHz, that is, the clock cycle or instruction time is 6.67ns.12-bit ADC, 16-channel.Event management
Modules EVA and EVB each have two general 16-bit timers, which can directly produce a 6-channel PWM signal. The synchronous serial peripherals interface SPI bus module requires only four lines to enable the MCU to communicate and exchange information with various peripherals in a serial manner. There are two SCI modules for serial communication interface, which is a general asynchronous communication interface UART. Each SCI module has the pins for sending output and receiving input.4 – line standard JTAG joint test interface, DSP chip for all the internal components of the program. Have a powerful central processing unit, responsible for program flow control and order processing, central processing unit (CPU) and memory have three between data bus, address bus and 3, respectively is program address, data read address and write address and program data read data bus, data bus, data/program to write the data bus.
