Power Electronics at the Heart of the Electric Vehicle

The automotive industry is shifting from mechanical drivetrains to power-electronics drivetrains, and the semiconductor content of a modern electric vehicle reflects that change. A battery electric vehicle relies on a traction inverter to turn battery DC into three-phase AC for the motor, an on-board charger to recharge the pack from an AC outlet, and a DC-DC converter to step the high-voltage bus down to the low-voltage rail that feeds body electronics. Every one of those blocks depends on power devices that combine high blocking voltage, low conduction loss and long-term reliability. China Resources Microelectronics, known as CR Micro, is a power-semiconductor IDM whose portfolio covers that entire chain, and BeiLuo supplies genuine CR Micro devices together with the application support automotive design teams need.

Why Silicon Carbide for the Traction Inverter

The traction inverter is the single most important power block in an electric vehicle because it governs efficiency, range and thermal load. A 400 V or 800 V battery bus is chopped by a three-phase bridge and fed to the motor, and the switching behaviour of that bridge determines how much energy reaches the wheels and how much is lost as heat. CR Micro's fourth-generation SiC MOSFET, the CRXQ75M120G4Z, is a 1200 V, 70 A device with on-resistance of 34 mΩ typical and 45 mΩ maximum in a TO-247 package. Compared with silicon IGBTs, a SiC MOSFET switches faster, has no tail current at turn-off and can therefore run at higher switching frequency with smaller magnetic components.

Switching Loss and Driving Range

Because SiC MOSFETs are unipolar devices, they do not suffer minority-carrier tail loss. That lets the inverter operate at 20 kHz and beyond without penalising efficiency, which in turn shrinks the DC-link capacitors and the motor ripple current. Higher efficiency directly extends driving range or allows a smaller battery for the same range, and it lowers the thermal load that the cooling system must remove. For an 800 V architecture the 1200 V rating provides the margin designers expect, while its positive temperature coefficient of on-resistance makes paralleling predictable.

Thermal Behaviour and Reliability

Automotive qualification demands operation over a wide temperature range and tolerance of repeated thermal cycling. The CRXQ75M120G4Z is built on a robust SiC process with a wide bandgap that supports high junction temperatures, so the heatsink and cooling plate can be simplified relative to silicon alternatives. Designers should still pay attention to gate-loop layout, because SiC switches fast enough that stray inductance in the gate and power loops can cause ringing. A compact gate loop with a controlled gate resistor and a properly referenced negative bias keeps the switching transient clean.

On-Board Charging and DC-DC Conversion

The on-board charger converts AC mains into the DC the pack requires, and it is normally a two-stage design: an active power-factor-correction front end followed by an isolated DC-DC stage. CR Micro's PIM IGBT modules, such as the CRGMP25T120DF2C3, integrate the power switches and the freewheeling diodes into a single insulated package, which reduces part count, simplifies assembly and improves thermal coupling to the heatsink. A 25 A, 1200 V module suits the PFC and DC-DC stages of a mid-power on-board charger, while the lower-current CRGMP15T120DF1C3 fits auxiliary DC-DC converters and lower-power OBC platforms.

Rectification with SiC JBS Diodes

Where designers want the lowest switching loss in rectification, CR Micro's SiC junction-barrier-Schottky diodes are a natural fit. The CRXB08D065G3 is a 650 V, 8 A third-generation device with essentially no reverse-recovery charge, and the CRXI10D065G2 is a 650 V, 10 A second-generation device specified with a low capacitive charge of 28 nC. Replacing silicon diodes with SiC JBS parts removes most of the reverse-recovery loss in the PFC and secondary stages, raises efficiency and reduces the electromagnetic interference that hard recovery produces.

Putting the Blocks Together

A typical automotive power architecture from BeiLuo combines the CRXQ75M120G4Z SiC MOSFETs in the traction inverter bridge, a CRGMP25T120DF2C3 PIM IGBT module in the on-board charger, and SiC JBS diodes in the PFC and rectification paths. The mix is deliberate: SiC MOSFETs give the switching frequency and efficiency that the traction stage needs, while the module-based IGBT approach keeps the on-board charger cost-effective at the frequencies where it operates. CR Micro builds both technologies under one roof, so the supply chain is simpler and process control is consistent across the platform.

Gate Drive and Layout Practice

SiC gate drive calls for a dedicated driver with enough source and sink current to charge and discharge the gate quickly, a split gate resistor to tune turn-on and turn-off separately, and short, low-inductance connections from driver to gate. The DC link should be decoupled with a high-frequency film capacitor placed as close to the bridge as possible, and the current-sense path must be isolated from the power loop. Screening and controlled edge rates keep radiated emissions within automotive limits.

Supply Chain and Support from BeiLuo

Automotive programmes run for years and cannot tolerate component surprises. BeiLuo maintains genuine CR Micro inventory across the MOSFET, module and diode families described here, and works with customers on forecast-based replenishment so that production lines stay fed. Documentation, traceability and change notification ship with the parts, and the field-application team can review thermal designs, gate-drive schematics and current-sensing layouts before a design is committed to production. Consistent material and a single IDM source reduce the risk of last-minute qualification work later in the programme.

Getting Started

Design teams can request samples of the CRXQ75M120G4Z, the CRGMP15T120DF1C3 and CRGMP25T120DF2C3 modules, and the CRXB08D065G3 and CRXI10D065G2 SiC JBS diodes for bench validation. BeiLuo will help map your voltage, current and thermal targets onto the CR Micro portfolio and propose a tailored bill of materials, so the move from concept to a validated power stage is straightforward.