26 – 28 June 2019 Shanghai, China More Info

Renewable Energy Technologies

Wednesday, 27th June 2018
Chairperson: Prof. Meiqin Mao, Hefei University of Technology, China

14:00 Active Clamping with Nonlinear Gate Voltage Control Unit

Ming  Wang, Delta Electronics (Shanghai) CO., LTD , China

In order to solve the problem of turn-off voltage stress of all controlled power semiconductor devices such as IGBT, active clamping is a common method. However, in the past research and application, the development of this technology is mainly focused on reducing the voltage spike of IGBT itself. In fact, the voltage spike of the freewheeling diode (FWD) of IGBT is also needed to be reduced, and it’s an even bigger challenge for active clamping. This paper proposes a nonlinear active clamping technology, which can effectively suppress the voltage spike of IGBT and its FWD by adding the nonlinear control unit of gate, and the relevant verification is done by experiments.
14:25 Power Optimization and Fault-Tolerant Control for Power Converter of Wind Energy Conversion System using PMSG


In a Wind Energy Conversion System , Generation and grid side are connected together through a fault tolerant bridge in which SVPWM modulation method for five leg converter suitable for machine and grid side converters is investigated. A five leg converter relizeas the independent controllable for the two sides, which reduces cost and work as a fault tolerant mode for wind energy conversion system. A conventional six leg converter has the capability to be reconfigured into five leg converter to continue the system power production. It proves that, it has higher reliability and nonstop service. Normal and fault tolerant modes are cost effective and are able to produce nonstop energy production under variable wind speed conditions. It avoids over current and is decoupled which gives a better use of the five leg converter under fault tolerant mode. This topology has a potential for DSP implementation. It reduces space and increases feasibility, validity and It can work as a single processing unit.
14:50 A Review on Low Voltage Ride-through for DFIG Based Wind Turbines


Doubly-Fed Induction Generator (DFIG) is popular for wind power applications however it is more vulnerable to faults and grid disturbance. DFIG should be capable to ride through the faults, especially Low voltages to meet new grid code requirements. In this paper LVRT technologies for DFIG are discussed in viewpoint of reactive power support and optimal performance during zero or low voltage events. The latest progress in LVRT technologies are presented by reviewing and
comparing the current technologies. Finally the possible future developments are discussed
15:30 Tandem Diode Solution with Split NPC Topology For 1500V Renewable Energy

Nosung Park, Vincotech , Korea

Tandem diodes exhibit low dynamic losses and low junction temperature characteristics, which leads to higher efficiency. It can be seen that the 7kHz loss of a typical NPC is equal to the 20kHz loss of Tandem diode. This allows for higher power density products using higher switching frequencies and is the basis for lower manufacturing costs.
15:55 Analysis on overvoltage stress of NPC2 power module in PV string inverter

Zhenbo Zhao, Infineon Technologies China Co., Ltd, China

The paper presents the investigation on the voltage stress with NPC2 power module in the 80kW PV string inverter. The experimental test bench has been built up to make the verification by optimizing the stray inductance of 3-level commutation loop. From view of system application, the key problem about passive overvoltage of the main bridge IGBT is firstly proposed. The working principle to generate the active and passive overvoltage in the power module is illustrated as well. It is analyzed to be active voltage stress mode how to be influenced by external factors like gate resistor, junction temperature and stray inductance. Further, the maximum current limit of power module is figured out in the passive overvoltage mode under the extreme working condition. Some design tips and application guidance of NPC2 200A in the system of 80kW power rating are concluded.