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Magnetics for the TIDA-011012 50 kW solid-state transformer cell
TIDA-011012 is a Texas Instruments reference design for a modular SiC solid-state transformer cell: a cascaded H-bridge on the medium voltage side, a 100 kHz dual active bridge for isolation and a 1.5 kV low voltage DC link. Cells are stacked in series, so every cell transformer has to insulate the full medium voltage of the stack. The power magnetics are not on TI's boards or in its bill of materials: the cell transformer and the grid-side inductance are left to the designer. This page explains what they have to do.
What the board is
- Modular cell for a three-phase SST, cells connected in series on the medium voltage side. Series stacking is what makes medium voltage reachable with devices rated for a fraction of it: the grid potential is shared between cells, and no single module has to hold all of it.
- 2.2 kV DC link on the medium voltage side and 1.5 kV on the low voltage side, about 50 kW per cell, bidirectional.
- DC/AC stage switching at 10 kHz in unipolar mode, with SiC power modules on the medium voltage side.
- Dual active bridge isolation stage at 100 kHz. The design guide considers a CLLC resonant converter and chooses the DAB for the simplicity of its bidirectional control.
- Module size 850 × 300 × 80 mm. The link between submodules is optical, which is how the isolation between them is obtained.
Source: Texas Instruments TIDA-011012 product page, design guide TIDUFJ2, schematics TIDME73 and bills of materials TIDME77, checked November 2026. The guide states that the transformer of each DAB cell must withstand the full medium voltage grid potential, but it does not publish its ratings, and the BOMs contain no power magnetics.
The magnetics on the board
| Part | What the design files publish | What decides the design |
|---|---|---|
| DAB cell transformer, T1 | One per cell, between the DAB primary H-bridge on the medium voltage board and the secondary H-bridge on the low voltage board. 100 kHz, about 50 kW, 2.2 kV to 1.5 kV, insulated for the full medium voltage potential. Not in the BOM | Insulation to the stack voltage, partial discharge, series inductance for the DAB and losses at 100 kHz |
| DAB series inductance, in the leakage or discrete | Not published | DAB power and ZVS range at the 2.2 kV and 1.5 kV operating points |
| Grid-side boost inductance of the cascaded H-bridge | Reduced by the phase-shifted carriers between cells. Value not published and not in the BOM | Ripple at the equivalent frequency of the whole stack, 50 Hz current and core material |
| Isolated auxiliary supplies of each cell | Integrated isolation modules on the gate driver side, 5 kVrms | Powering every cell across the medium voltage barrier |
What the public documents do not say
Each cell has a medium voltage board with two H-bridges, the grid-side AC/DC stage and the primary of the DAB, and a low voltage board with the DAB secondary. The DAB outputs of all cells are connected in parallel on the 1.5 kV side. The design guide does not give the number of cells, the series inductance of the DAB or the insulation level of T1, and the published bills of materials contain only small signal inductors: the cell transformer and the grid-side inductance are not part of the design files. Those numbers define the transformer, and we confirm them with you before designing.
Why the magnetics are harder than in a low voltage DAB
Each cell transformer only processes the cell voltage, 2.2 kV to 1.5 kV, but its insulation sits between a medium voltage cell and the low voltage side. That puts kilovolt-class insulation inside a 100 kHz transformer. The insulation distance then becomes the largest contributor to the leakage inductance, so insulation design and series inductance design are one decision. The insulation must also be free of partial discharge at the operating voltage, which rules out constructions with air pockets and requires controlled field at conductor edges.
On the grid side, unipolar switching doubles the ripple frequency of each H-bridge, and in a cascaded H-bridge the carriers are normally phase-shifted between cells, which multiplies it again by the number of cells. The boost inductor of the whole stack therefore sees ripple at about twice N times the switching frequency, which is why its value can be small, but it still carries the full 50 Hz current.
If you change the design
More cells per phase raise the insulation level of every cell transformer. A higher cell voltage or a different DAB frequency changes turns, core size and the series inductance. Changing the number of cells also changes the ripple frequency seen by the grid-side inductor and therefore its value.
What to send us
The reference number, the number of cells per phase and the grid voltage, the insulation voltage to ground and the partial discharge requirement, the DAB series inductance you need, the cooling and the quantities you expect.
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.
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