Power Electronics Development Center
NREL collaborates with Semikron, National Instruments and the California Energy Commission to develop Modular 50 kW Power Block
Modular 50 kW Power Block and Advanced Power Electronics Controller
The Modular 50 kW Power Block and Advanced Power Electronics Controller system integrates renewable and distributed energy systems into the Smart Grid with improved flexibility, scalability, and cost effectiveness.
To integrate renewable energy systems into the electric grid, utilities use power inverters which are usually designed to work with only one type of technology such as a solar array. Not only does the single-technology design limit capability, but it also makes the devices more expensive to purchase and maintain. Developed by the National Renewable Energy Laboratory (NREL) with industrial partners Semikron and National Instruments, and funded by the California Energy Commission, the Modular 50 kW Power Block and Advanced Power Electronics Controller system solves these problems by providing flexibility so that it can be used for various renewable and distributed energy systems, including:
• Photovoltaics
• Small wind
• Battery
• Fuel cell
• Flywheel
The use of a common inverter system for different distributed energy applications—along with common, off-the-shelf power block components—makes mass production possible, which will bring down production and maintenance costs while lowering engineering effort. Additional advantages of this power block design are its paralleling capability, ease of system design and assembly, and reliability. The system is also scalable: more than one power block can be connected together for higher
power ratings.
Power Block
The Modular 50 kW Power Block consists of the commercially successful Semikron SKiiP3 module with 1200V insulated gate bipolar transistor (IGBT) switches and anti-parallel diodes arranged in three-phase bridges. It also includes gate drivers, DC bus film capacitors, current sensors, a DC voltage sensor, a temperature sensor, a digital controller board, connectors, and bussing—all mounted on an air-cooled heat sink. The Semikron SkiiP3 IGBT module has features such as pressure contact technology, an integrated driver, and protection that have been fully integrated and tested.
Advanced Power Electronics Controller
NREL worked with National Instruments to develop a state-of-the-art controller board for these power blocks. This new controller board is based on National Instruments’ single-board RIO platform, which includes a 400 MHz PowerPC processor and Xilinx Spartan-6 LX45 FPGA.
The deployment-ready controller board is designed for high-volume production of grid-tied inverter, DC-DC converter, and motor/generator drives and has input-output signal compatibility with most standard IGBT intelligent power modules. The controller board provides advanced programming capability for use in Smart Grid applications.
Inverter Cabinet
NREL demonstrated operation of the 50 kW power block prototypes by building a three-phase DC-AC inverter. The power block is packaged inside a 5x2.5x2.5 foot inverter cabinet which also contains:
• Three-phase filter inductor
• Filter capacitors
• External voltage and current sensors
• DC contactor
• Three-phase AC contactor
• Pilot relays
• Power supply.
The inverter design includes protective devices to suppress surges, protect against ground faults, and ensure emergency shut off.
Wireless Interface
The 50 kW Power Block-based inverter system can be monitored and controlled through a wireless Apple® iPad® application. Through the application, an operator can view real-time measurements, control the mode of operation and other settings, and export customized data. This iPad application demonstrates how the modular power block based power electronics can blend into the Smart Grid monitoring and control framework.
Prototype Success
NREL has successfully conducted laboratory testing of the Modular 50 kW Power Block and Advanced Power Electronics Controller system prototypes, and continues to refine the technology and conduct field testing.
The next step is to transfer the technology to industry so that optimized power converters can be developed that take full advantage of this modular power block.
Helpful Websites
NREL Electricity Integration Research
Department of Energy Office of Electric Delivery and Energy Reliability
California Energy Commission
