Wednesday morning, 26 June 2019
Chairperson: Prof. Meiqin Mao, Hefei University of Technology, China
Paralleling of medium-power IGBT modules in windmill converter to reduce size and cost
Xiaoming Liu, Semikron, China
Flexibility, price pressure and second source are the main factors to change the design strategy for windmill converter. High power modules (1400A/1700V) are used for windmill converter (1-1.5MW) since the past years. Paralleling knowledge of IGBTs was uncommon. Design of 4 standard IGBTs with different driver solutions will be shown and test results will be explained in the paper. Parallel inductance will become unnecessary if the IGBT driver design can be optimized. Bundle solutions (IGBT driver and IGBT module from one supplier) will be introduced .Investigation in DC bus capacitor design and lifetime calculation (capacitor and IGBT module) show new results in DFIG- and full size windmill converter design. Low frequency handling will be explained and influence in IGBT design will be shown .Common windmill converter designs are in half bridge topologies. One windmill converter contains 12 half-bridges and one half-bridge for brake chopper. We will discuss the change from half-bridge design (GB) to 6-pack design (GD). In our paper we will introduce a 1.5MW windmill converter design with 450/600A/1700V IGBT modules.
3-level-topologies for windmill converter
Fengjie Zhu, Semikron, China
To achieve lower cost per KW, bigger and bigger wind turbine is becoming a clear trend in the market today. For new offshore installation, 5MW and higher power wind turbine is common. Traditional 2 level low voltage converter is no longer appropriate for multi-MW converter because of higher current stress and cost.
By using 3 level topologies, the output voltage of converter can be increased even with same rated voltage IGBT. Higher output voltage can dramatically save the cost of cable inside tower.
Compared to traditional 2 level topology, NPC or ANPC topology can reduce the du/dt, smaller choke filter can be used and the output waveform is closer to sinusoidal, which means lower THD.
In China, all major windmill converters have started pre-study or even already developed 3-level converter. IGBT module suppliers have to adjust their product portfolio to meet this trend.
3-Level NPC Topology in Wind Inverter
Xiangfei Meng, Danfoss Silicon Power, China
There is a trend to use 3-Level solution to replace traditional 2-Level solution in some application.
Efficiency, cost, higher switching frequency and small footprints are all highly relevant value propositions for those applications such as APF, Solar etc. Selecting 3-Level topology can decrease the size of the
filter because of lower switching voltage and feasible higher switch frequency. Losses in 3-Level IGBT module will be lower than 2-Level module can also help to increase the efficiency remarkably. In this paper an 3-Level IGBT power module for wind inverter 1050VDC system is presented. The cons and pros of 3-Level in wind inverter will be discussed.
Control Strategy of Parallel Unidirectional Controlled Rectifiers for Static Reactive Power Compensation
Changgeng Tian, China University of Mining & Technology, China
Since unidirectional rectifiers be widely used in the commercial market, it’s an economical solution for improving power quality in industrial applications. Due to input current distortions, the amount of reactive power contributed from an individual unidirectional rectifier will be restricted. To address this problem, this paper introduces the parallel unidirectional rectifiers, and provides a control scheme based on such parallel structure for compensating reactive power.