The Development Of Control System For High Voltage Converter

With the rapid development of power electronic technology and asynchronous motor control technology, the speed regulation control system also developed rapidly. As the comprehensive use and better performance of the speed regulation control system, it has been a trend that the AC speed regulation system replaces DC motor speed regulation system. At present, the middle and low power inverters have been researched deeply. But there are many problems need to be studied in the high voltage inverter's application. The research of control system is one of the hotspots. There are much space in developing a control system which were rapidly response,synchronously control,easily function extending and steady. Therefore, it is of great necessity and significance to develop more advanced control system for high voltage inverters.The paper introduce some typical structure of converters firstly, and summarize the present status and the development tend of high voltage inverters. After that, the paper narrates the background and important application of control system for high voltage converter.After analyzing the topology structure and working principle of three-level neutral-point-clamped(NPC) inverter, the paper introduce the design principle, function configuration and the total structure of hardware design for the control system. The control system mainly include the CPU system part,peripheral input/output transformer part. The CPU part is the design emphasis of control system. Because the NPC inverter use many IGCTs which need to be controlled in synchronization way and have complicated topology structure, so the CPU part adopts DSP, FPGA and CPLD integration structure. The complicated calculation is accomplished by DSP because of it's powerful calculation ability and abundant resource. The FPGA make use of it's parallel executing program ability to realize many IGCTs triggering in same time. The CPLD is used to checkout the output control signals. In order to avoid the dangerous cases caused by hardware fault. That measures improve the inverters reliability and security.The speed regulation system has many control and modulation method. A certain control method can choose different modulation to realize. The paper introduce a few of common control and modulation methods. In order to fulfill the demand in the application, the paper adopts U/f control and SPWM (sinusoidal pulse width modulation) method. In the U/f control, the paper use some optimizing method, nonlinear acceleration/deceleration curve and asymmetry regular sampling method. The paper explains the calculation method and formulas, and also explain the special situation need to be considered and the corresponding measures.The software design was divided into several different parts: DSP, FPGA and CPLD. In order to increase the readability and transplantable ability, the DSP software design adopted module design method. The paper introduce the soft flow with flow chart, and the principle of designing different module. The FPGA soft has five parts, cooperate with DSP to complete PWM signal's calculation and output. The paper introduce each module's function and software design. CPLD monitor the output signals, and shut down the signals when malfunction occur.After manufacturing the control system for the speed regulation system, the system have been tested and simulated. The paper analyzes the experiment's result and introduce each test's content and basic conclusion. The analyse result indicate that the control system reaches the design requirement and fulfill the actual application.