Study On The Digital Control Of Diode-clamped Three-level Inverter

With the demand of users’ on increasing the capacity of power supply and high power quality, the waveforms control technique of inverters become more and more extensive application. Based on the application of modularized UPS, Diode-clamped three-level inverter is selected to be the circuit topology,For the hardware selection, waveform quality control strategy, software process of three-level inverter, this paper carries out the theoretical analysis and design, which aims to improve the performance of system output voltage.In this paper, the main circuit topology is a single-phase diode-clamped three-level inverter, according to the working principle of main circuit topology, using a unipolar SPWM modulation method. The mathematical model of three-level inverter is established, the system uses a single voltage loop control, also join three control ways: the former reference voltage feed-forward, capacitive current compensation and error parabola regulation which to improve the output waveform quality of inverter. Three factors on concerning waveform quality are analyzed in detail, including dead time, SPWM over modulation and delay of digital control. For these three areas, this paper put forward the corresponding control strategy.This paper designs the software and hardware of three-level inverter system. In terms of hardware, this paper selects Infineon IGBT SGL160N60 UFD, designs the voltage and current sampling conditioning circuit, the over-current protection circuit and the auxiliary power. In terms of software, a combination of TMS320F2810 and EP5M240ZT100C5 N is used digital control. This paper designs software flow chart so that have a great help for programming.Putting up the 3k VA three-phase inverter platform with the digital control and C language program is written, and a prototype has been built and tested. Finally, the simulation and experiment validate the correctness and feasibility of theoretical analysis and control method.