Home / Reference Designs / CRD60DD12N-GMB
Magnetics for the CRD60DD12N-GMB 60 kW dual active bridge
CRD60DD12N-GMB is a Wolfspeed reference design for a 60 kW isolated dual active bridge on 1200 V SiC modules. It has no separate series inductor: the 7.5 µH leakage of the transformer is the series inductance. That single number sets the power range, the current and the derating of the converter, and it comes from the winding geometry.
What the board is
- 60 kW isolated, bidirectional dual active bridge at 100 kHz, adjustable from 80 to 100 kHz.
- Input 700 to 900 V, output 400 to 900 V, with power derated below 600 V. Output current up to 100 A.
- Two 1200 V, 11 mΩ Gen 4 SiC full-bridge modules on one cold plate. 99.2 % peak efficiency, above 98.8 % over 20 kW, 10.5 kW/L including the transformer.
- The transformer is not included with the board. Wolfspeed recommends a custom transformer with a measured leakage inductance of 7.5 µH and a magnetising inductance of 329 µH at 100 kHz, 202 × 81 × 73 mm, cooled on a liquid cold plate in series with the power stage.
- The two isolated full bridges can also be used for a series resonant converter with an appropriate transformer and external resonant components.
- The published test sweep covers 10 to 23 kW at 800 V in and out, 100 kHz and 200 ns dead time.
Source: Wolfspeed CRD60DD12N-GMB product page and user guide PRD-10001, May 2026, checked November 2026. The power board BOM contains no power magnetics: the transformer is the only one, and it is supplied separately.
The magnetics on the board
| Part | What the user guide publishes | What decides the design |
|---|---|---|
| DAB transformer with integrated series inductance | Lσ = 7.5 µH and Lm = 329 µH at 100 kHz, 202 × 81 × 73 mm, liquid cold plate, litz leads | Leakage value and tolerance, losses at 60 kW and 100 kHz, thermal path to the cold plate, insulation |
| Separate series inductor | None | Removed by design |
| Resonant tank, if the board is used as a series resonant converter | External resonant components, no values given | Resonant inductor and transformer designed as one tank |
What the 7.5 µH does to the converter
With single phase shift modulation, the maximum power of a DAB is n·V1·V2/(8·fs·Lσ). At 800 V on both sides, 100 kHz and 7.5 µH, that is 107 kW, so 60 kW needs a phase shift of about 30°. At 600 V on the output, the maximum falls to 80 kW and 60 kW already needs 45°, and below about 450 V 60 kW is no longer reachable. That, together with the 100 A output current limit, is why the power is derated below 600 V. A leakage 10 % higher than 7.5 µH would move that limit up by about 10 % in voltage.
The 329 µH of magnetising inductance adds a magnetising current of about 12 A peak to peak at 800 V and 100 kHz. It helps soft switching at light load, and it is the second number to hold in production.
The published test points are consistent with that leakage. At 800 V on both sides, 7.5 µH gives 11.5 kW at a 5° phase shift and 22.4 kW at 10°, when the phase shift is measured over the full switching period. The user guide reports 10 to 23 kW for 2.5 to 5.0°. Those two sets are consistent if the guide's phase shift is defined over half a period, which would make its 5° equal to 10° of the full period. The guide does not state its convention, so this is our deduction and not a published fact.
Why it is not a catalogue part
Wolfspeed itself calls the recommended part a custom transformer, and it does not ship with the board. The series inductor was removed by designing its value into the leakage, and that number comes from the winding geometry and from nowhere else. A transformer for a different voltage, power or frequency needs a different leakage, and the part cannot exist before that design does.
If you change the design
For the same power at a lower output voltage, the leakage has to be lower. For a higher power at the same voltages, it has to be lower too. For a lower frequency, it has to be higher. Each change moves the winding spacing, and often the turns and the core. When the leakage the converter needs cannot be reached inside the transformer, a small external inductor completes it.
What to send us
The reference number, input and output voltage ranges, power, switching frequency, the series inductance and its tolerance, the magnetising inductance you want for ZVS, the cooling and the isolation standard.
We aim to send an engineering answer with a first design proposal inside 24 hours, then 4 to 8 weeks from an agreed design to a prototype, subject to raw material stock. No minimum order quantity.
Straight answers