Research On The System Of Single-phase On-line Digitized UPS

The development of power electronics technology promotes the progress of the power equipments’innovation. High quality power is needed for different electrical equipments in the special occasion.Traditional analog control technology more and more less applied, and high-performance digital controltechnology is gradually replacing analog control technology. Digital control benefits form the flexibility andcost advantages of its intrinsic motivation. PWM control technology not only has been fully applied in thefield of motor control, but also play a pivotal role in digital power and inverter.There is no doubt that it is anintegral part of industrial automation. And with technological advances in microprocessors, digital controltechnology can meet the needs of various industrial control field. Inverter is the core component ofUPS(Uninterruptible Power Supply), high reliability digital control theory is critical for UPS, it affects boththe dynamic response and steady state accuracy of the system.In this paper, single-phase on line UPS for digital control technology is studied including theoretical andexperimental research. The main content and the results are as follows:(1) The main power stage circuit topology of single-phase half-bridge inverter is analyzed and themathematical model is established. Compared with the previous modeling analysis, this paper proposes adepth simplified mathematical model of the half-bridge inverter. Constructing the system control loop basedon the thought of closed-loop gain shaping. It aims to build an expected shape of the closed loop gain of thethe transfer function and a reasonable bandwidth for minimizing the impact of the output feedback.Experiment result shows that the method is simple and the control method owns a high performance.(2) The basic principle of the control algorithm of closed-loop gain shaping is introduced and then controlmodel and controller parameters is given. On this basis, using the soft of MATLAB/Simulink component toestablish a2kilowatts inverter control simulation model for steady-state circumstance and dynamicsimulation experiment. In each case, the simulation results shows the single-phase sine has a good dynamicperformance.(3) The UPS system of main power stage circuit is analyzed and designed. It includs BOOST circuit and thecorresponding control circuit. The difficulty lies in the design of loop compensation circuit.We use the chipof UC3844to control BOOST circuit. Through step debugging, system meets the experimental results.