Design And Application Of Variable Frequency Power Supply Based On DSP

With the development of power electronic technology and control technology, variable frequency speed control technology is also in constant developent and renewal. Especially the new power electronic devices (such as IGBT) and high performance microprocessor (such as DSP) are developed rapidly, it has greatly reduced the volume,at the same time the cost performance has been greatly improved, frequency conversion technology ushered in a new era. IGBT (insulated gate bipolar transistor)can makes the emergence of the converter efficiency to be effectively improved by use it as a variable frequency power supply quality,the power element is good, high efficiency, low heat loss, low noise, small size and can greatly extend the power of life. Therefore, IGBT has been widely used in frequency domain. At the same time, DSP (digital signal processor) emerged with the need of the rapid development of computer and information technology. Compared to previous use of single-chip microcomputer, high speed data calculation ability of DSP is the single chip microcomputer can not match, this time needs to be handled with the increasingly large amount of data, even more, the requirement of real-time and accuracy is also rising water bed height, storage capacity and computing ability of DSP outstanding makes it in the need for a complex signal analysis advantage operational aspects of the increasingly obvious. The DSP can and SPWM (sinusoidal pulse width modulation) combines the advantages of both at the same time to play out, variable frequency power supply composed of them control system to meet the requirements of control precision at the same time, meet the requirements of real-time control, otherwise it can realize the continuous smooth adjustment.Therefore, based on the relevant literature review, research and analysis of the designmethod of inverter power supply based on DSP’s existing, and its shortcomings, has carried on the design of main circuit of inverter power supply (Variable frequency power supply rectifier circuit design, Variable frequency power inverter circuit design, The main components of the circuit selection)and the control system of variable frequency power supply based on DSP(The control system hardware design,The control system software design):(1)Based on the analysis of frequency conversion power supply rectifier circuit of the existingelectromagnetic stirrer and the actual needs, we designed a three-phase uncontrolled rectifier circuit which use the diode to rectify, the circuit structure is relatively simple, control technology is also very mature, it can fully satisfy the needs of the electromagnetic stirrer.(2)Through the research and analysis of the frequency power inverter circuit current, a three-phase inverter bridge circuit which use the IGBT to do the power component is design sd, the DC part front-end circuit use the capacitance filter, it can not only make the frequency conversion power supplyoperation more stable, but also can effectively reduce the impact of small oscillation ripple on the inverter circuit. The DC part also connected with a leakage detector for real-time detection of leakage current, load size and feedback of information to the control system. DC AC link using the IGBT, low conductivity and high input impedance which has the advantages of MOSFET and GTR is ideal for frequency power inverter circuit.(3)Through the research on variable frequency power supply based on DSP control circuit, aprotection function can achieve a variety of control circuit design, mainly through the on-offcontrol contactor to realize the effective control of the circuit. Power supply switching power supply using single-phase bridge rectifier, high efficiency and relatively full wave rectifiercheaper.(4) Through the research on variable frequency power supply based on DSP, designed a set of system which can remote operation, aiso the software control programs can complete local operation.Man machine interface design based on WINDOUS platform, the interface is clear andconcise, simple operation, convenient user operation on the spot Wince remote operation for remote control and parameter setting, and it can be stored for up to a year’s condition historyreference for users. The dispatch management system enables the user to the centralized and unified management, the realization of the production management automation.In addition, in the practical application of engineering, provides a solution for some fault often appear in the man-machine interface, debugging process of variable frequency power supply are described in detail, including the no-load debugging and load testing and safety precautions.Variable frequency power supply based on DSP is designed in the thesis, the system is not only stable and reliable, with high power factor, also when used in electromagnetic stirrer, it can improve steel internal crystal structure,improve steel quality, improving the rate of finished products,expand casting varieties, improving technical conditions and so on.