New Industry Products

SiC-based 60kW Interleaved Boost Converter Reference Design

January 28, 2019 by Paul Shepard

In solar power generation, the photovoltaic cells utilize the sun's energy to generate dc voltage which is usually in the range of 400Vdc to 600Vdc. This dc voltage needs to be boosted to approximately 850Vdc so that an inverter can generate 480Vac to feed the power of PV cells into the power grid. Increasing the efficiency of the power conversion process enables designers to build smaller, lighter, and less expensive solar power converters.

For these solar energy systems, Wolfspeed has introduced the CRD-60DD12N, 60kW interleaved boost converter reference design based on Cree's C3MTM 1200V, 75mΩ SiC MOSFET which comes in a TO-247-4 package with a Kelvin source availability. The availability of Kelvin source reduces the inductance of gate and Kelvin source path which in turn reduces the overall switching losses.

In addition to that, the CRD-60DD12N60 kW interleaved boost converter utilizes Cree's newly-developed CGD15SG00D2 isolated gate driver board which is tailored to the drive requirements of Cree's generation 3 C3M SiC MOSFETs.

This reference design consists of four interleaved 15kW boost converters. Cree's C4D10120D SiC Schottky diodes, which possess low voltage drop and zero reverse recovery features, have also been used.

Top-level diagram of the CRD-60DD12N, 60kW boost converter (click on image to enlarge)

The PCB has been divided into two sections, one is the boost control board and the other is the boost power board. Two of the Texas Instrument's UCC2822 interleaved dual pwm controllers have been used on the boost control board. Each controller IC provides pwm switching signals to the two interleaved boost stages.

The boost power board mainly consist of power switching devices, passive elements (including boost inductor and capacitor) and voltage/current sensing circuitry. There are three pin header connectors (CON217, CON218, CON219) that plug boost control board into the boost power board.

(click on graph to enlarge)

The efficiency of the CRD-60DD12N, 60kW interleaved boost converter was measured under various load conditions (10 kW - 60 kW) while keeping the input voltage constant at 600Vdc. The maximum efficiency achieved by this reference design was 99.5%