New Industry Products

SiC Module enables >98% Efficient 300kW Three-Phase Inverter Reference Design

June 24, 2019 by Paul Shepard

The CRD300DA12E-XM3 300kW three-phase inverter reference design from Wolfspeed demonstrates high system-level power density and efficiency obtained by using Wolfspeed's new XM3 module platform. The XM3 is optimized for SiC MOSFETs in a high-density, low-inductance footprint, which can reduce system losses and simplify overall design for low-loss, high-frequency operation. The three-phase inverter has greater than 2X the power density of comparable Si based designs and greater than 98% efficiency.

This reference design includes a high-performance cold plate, optimized laminated bussing for reduced power loop inductance, dc-link capacitors, sensors and control hardware.

Targeted applications include motor and traction drives, grid-tied distributed generation, smart grid / flexible ac transmission systems, active front ends, uninterruptible power supplies, and high-efficiency converters.

Related: 10kW/10kVA Three-Level, Three-Phase SiC AC-DC Reference Design

XM3 Module - SiC optimized footprint.

Summary of technical features:

  • Optimized for Cree's All-SiC, Low Inductance, Conduction Optimized XM3 Power Module
  • Complete Stackup, including: Modules, Cooling, Bussing, Gate Drivers, Voltage / Current Sensors, and Controller
  • High-Frequency, Ultra-Fast Switching Operation with Ultra-Low Loss, Low Parasitic Bussing

(click on table to enlarge)

This reference design has a 900Vdc bus max and 360ARMS phase current max. It is compact and lightweight at only 9.3L and 6.2kg with a power density of 32kW/L, about 2x traditional Si inverter.

XM3 inverter reference design interior view

It is Wolfspeed's highest power density inverter. The XM3 module enables low-inductance bussing for reduced system-level parasitic inductance leading to an efficiency greater than 98%.

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The XM3 platform enables simple bussing and the low inductance, high-ripple current film capacitors create a total power loop inductance of only 12nH. The highly-integrated enclosure allows for a very compact and lightweight inverter that includes a high-performance liquid-cooled cold plate.

Laminated dc bussing cross section

The non-planar module power terminals simplify bussing with no bends or standoffs. The use of low-inductance, high-ripple current film capacitors (300µF, 1000V) results in a combined bussing and capacitor inductance of 5.3nH. A total loop inductance including module, bussing, and capacitors of 12nH produces a total system stray inductance less than the internal stray inductance of standard power modules.

Switching performance (click on graphs to enlarge)

The low inductance module and system enable low overshoot and ringing even under fast switching. For RGext = 0 Ω, VDS = 840V, IDS = 600A: the overshoot voltage is 240V, with dv/dt 19 V/ns and the overshoot current is 110A, with di/dt 15 A/ns.