Lan Zhiming

Investigation on IGCT-based five-level NPC/H-bridge high power converter

Nowadays the medium and high voltage large power AC-DC-AC converters are used in various industrial fields. The integrated gate commutated thyristor (IGCT) is applied to high power AC-DC-AC converter on a large scale due to its excellent characteristics. In this paper the investigation on IGCT-based five-level NPC/H-bridge high power converter is proposed. Each phase of the five-level NPC/H-bridge converter is composed of two IGCT-based three-level neutral point clamped (NPC) legs in an H-bridge form. The converter adopts modular design and the module of IGCT-based three-level NPC legs has been developed. One type of modulation scheme based on three-level SVPWM is introduced and the experiment result is showed in this paper.

Investigation on the control strategy of high power NPC/H-bridge inverter

Large power electronic converters are widely used in the oil and gas transportation, pumped storage and other fields. In order to achieve higher voltage and power, NPC/H-bridge multi-level topology is the most common solution. In this paper, the topology and control strategies of NPC/H-Bridge converter are investigated in details. Finally the PSIM simulation results validate that the control strategy of 3-segment switching pattern has a better performance.

Investigation on the switching property of IGCT used in large power voltage source inverter

The integrated gate commutated thyristors (IGCTs) have the features of high current, high voltage, high reliability, compact structure and low loss. They have been widely used in large power voltage source inverter systems now, and they have extensive application prospect. In the paper, the performance of IGCT and diode is introduced. With the function models of IGCT and diode, the switching property of IGCT used in large power voltage source inverter is investigated. And part of the simulation results are verified with experiment results. During the turn-on process of IGCT, over current through it will appears for the reverse recovery of the fly-wheel diode. During the turn-off process of IGCT, over voltage over it will appear for the existence of the stray inductance and the clamp inductance. The property of the snubber diode and the parameters of the circuit will also influence the turn-off process of the IGCT. In order to ensure the performance reliability, the parameters of the diode and the circuit should be carefully chosen.

The subsection synchronous modulation strategy for high power NPC/H-bridge inverter

Large power electronic converters are widely used in the oil and gas transportation, pumped storage and other fields. In order to achieve higher voltage and power, multi-level topology is the most common solution. In this paper, the topology and subsection synchronous modulation strategy of NPC/H-bridge inverter are investigated in details. When the modulation index is different, SPWM or SHE will be chosen. Finally the PSIM simulation results validate the control strategies correctly and can be applied in the actually.

Study on large power converter system for rolling mills

The performance of the large power converter system for rolling mills should meet the need of production technology and adapt to the requirement of the electric network. In the paper, the cycloconverter system is introduced. With the development of large power electronics, application of the large power converter using the self-controllable devices such as IGCT and IGBT becomes the trend. The three-level AC-DC-AC converter system with IGCTs whose rated power is 7.5MVA has been developed and put into use. And it is estimated that the AC-DC-AC converter system will be used in the drive for rolling mills in the near future.

Investigation on the 30MVA IGCT-based voltage source converter

The high power AC-DC-AC converters are widely used in various industrial fields. The integrated gate commutated thyristor (IGCT) is applied in medium and high voltage converter on a large scale due to its excellent characteristics. In this paper the investigation on the 30MVA IGCT-based high power voltage source converter is presented. The 30MVA converter is composed of two 15MVA IGCT-based five-level converters and the outputs of the two converters are in parallel connection. Each phase of the 15MVA five-level converter is composed of two IGCT-based three-level neutral point clamped (NPC) legs in an H-bridge form. The detailed topology design of the 30MVA large power converter is introduced in this paper. The modularization design is adopted in the converter to reduce its size and improve its power density. The power module of IGCT-based three-level NPC leg has been developed. The switching characteristics of IGCT are investigated and the influences of snubber circuit are simulated. The experiment of turn off process of IGCT is carried out. One type of carrier-based modified in-phase disposition (IPD) modulation scheme is researched and simulated.

The development of IGCT-based large capacity three-level dual-PWM converter

In media and high voltage large capacity converter systems the Integrated Gate Commutated Thyristor (IGCT) take the place of Gate Turn Off Thyristor (GTO) duo to its outstanding performance. And IGCT-based large capacity three-level converters are widely used in industrial motor-driving field. In this paper the development of a set of IGCT-based large capacity three-level dual-PWM converter is introduced. The converter includes PWM rectifier, DC capacitors, PWM inverter. The topology of the converter is given. The close-loop control strategy and SVPWM algorithm of PWM rectifier is presented in this paper. The control strategy and algorithm of the PWM inverter is also presented. The experiments were performed and the results show that the converter reaches the design requirement and has excellent performance.

Investigation on the subsection synchronous modulation strategy for high power NPC/H-bridge inverter

Large power electronic converters are widely used in the air compressor, oil and gas transportation, metallurgical transmission and other fields. In order to satisfy the acquirement of high power, multi-level topology is the most common solution. In this paper, the topology and subsection synchronous modulation strategy of NPC/H-bridge five-level inverter are researched in details. When the modulation index is different, SPWM or SHEPWM will be chosen. The comparison between different modulation strategies is given through the simulation results and indicates the advantage of selected strategy. The experimental results validate the correctness of selected control strategies and can be applied in the actually.

Study on the losses of the large power voltage source converter with IGCTs

The large power three-level voltage source converters with IGCTs have been widely used in medium or large power drive systems and will be promising in the near future. And the losses of the converter should be carefully considered during the design of the cooling system of the converter. In the paper, the losses of IGCT device are analyzed and verified with experiment. Then with the system simulation model of the large power converter, the losses of the devices and the efficiency of the converter are also studied.

Study on the over-current protection method of the large power inverter with IGCTs

Large power three-level voltage source inverters with IGCTs are widely used in medium and large power drive systems now and have prospective future. Measures should be carefully taken to protect the inverter when over-current occurs due to every reason, especially that due to short circuit in the load or in the inverter itself. The short circuit process of the inverter with IGCTs is analyzed. With software simulation and experiment, the influence of some circuit parameters on the short circuit process is investigated. Then the schematic diagram of the inverter with over-current protection function is designed. System experiments show the inverter has excellent performance.