EV chargers, converters and ADAS modules are sealed against water, dust and salt, so a fan is not an option. How solid-state ionic wind cools inside them.
Open the housing of a production on-board charger and there is no fan in it. There is a die-cast aluminium case, a gasket groove, a gap filler pressing the power stage against the wall, and a volume of internal air that never really moves. Every watt leaves through metal. That decision, taken so the unit survives road salt, brake dust, pressure washing and years of vibration, sets the power ceiling on nearly every electronics box in an EV.
Sealed enclosure cooling is the practice of removing heat from electronics inside an ingress-protected, gasketed housing that cannot draw in outside air, so heat has to reach the housing wall by conduction, internal convection and radiation instead of by forced ventilation.
That covers the on-board charger, the DC-DC converter, the inverter, the ADAS compute module and the infotainment head unit. None can take an intake fan without losing the ingress rating that made it viable.
A sealed housing contains air, and that air is doing almost nothing. Buoyancy drives a weak recirculation, boundary layers on hot surfaces stay thick, and magnetics windings, film capacitors and the top side of a board facing the lid derate first because the air touching them will not move.
So sealed designs go conduction-first: gap pads, potting, metal-core boards, a boss under the hottest die. That carries two costs. Interface materials pump out over thermal cycles, and the path only serves parts you can press against the wall.
A dielectric barrier discharge actuator is two electrodes separated by a thin dielectric, one exposed and one encapsulated. A kilovolt-class AC drive breaks down a shallow layer of air, ions accelerate along the surface and drag neutral air with them, producing a wall jet of a few metres per second, as set out in how DBD plasma actuators work. The device is roughly 200 micrometres thick with no moving parts, so it laminates onto the inner face of a lid, onto a fin, or onto the board.
The discharge is non-thermal, so the actuator adds no meaningful heat to what it cools, and it exchanges no air with the outside. It reuses the air already trapped in the housing, stripping the boundary layer off hot parts and driving it onto the case wall.
In the most relevant published measurement, an ionic wind superimposed on an existing 0.3 m/s bulk flow gave roughly a factor-of-two increase in the average heat transfer coefficient and about 20 K of additional cooling, drawing under 100 mW (67 mW at 15 µA) [1]. Note the regime: 0.3 m/s is far closer to what a closed housing sees than to anything a fan produces, and reviews place ionic wind as a local enhancement, not a bulk air mover [2]. That is why this class of solid-state cooling suits sealed boxes. The alternative there is no airflow at all.
| Approach | Moving parts | Needs air exchange with outside | Dominant wear mechanism | NVH contribution |
|---|---|---|---|---|
| Conduction to housing, potting | None | No | Pad pump-out, dry-out | None |
| Internal recirculation fan | Yes | No | Bearing wear, lubricant loss | Tonal, structure-borne |
| External fan on a finned case | Yes | Yes, for the fan | Bearing wear, dust ingestion | Broadband, blade tone |
| Piezoelectric or MEMS blower | Membrane | No | Membrane fatigue | Tone at drive frequency |
| Thermoelectric module | None | No | Solder fatigue under cycling | None, but adds waste heat |
| DBD plasma actuator | None | No | Dielectric ageing under stress | None mechanical, EMC to manage |
Consumer electronics tolerate fans because the product is replaced long before the bearing is. A vehicle cannot. Service lives run to fifteen years, and the box is rarely serviceable without pulling trim, a dashboard or a battery tray. A rotating part inside a sealed housing is a failure nobody has scheduled. AEC-Q100 shows the cycling involved across four operating temperature grades [3]:
| Grade | Ambient operating range | Temperature cycling (test A4) |
|---|---|---|
| 0 | −40 °C to +150 °C | −55 °C to +150 °C, 1500 cycles |
| 1 | −40 °C to +125 °C | −55 °C to +150 °C, 1000 cycles |
| 2 | −40 °C to +105 °C | −55 °C to +125 °C, 1000 cycles |
| 3 | −40 °C to +85 °C | −55 °C to +125 °C, 500 cycles |
A component with no moving mass has an easier time with the vibration profiles of ISO 16750-3 [4]: a 200 micrometre laminate adds almost no inertial load and no member that can fatigue.
In a combustion car, engine and exhaust noise masked a great deal. In an EV at low speed the cabin noise floor drops and what was inaudible becomes a warranty conversation. NVH teams weight tonal content far more heavily than broadband noise at the same level, because a tone is identifiable well below the point where broadband noise is noticed. A fan's blade-passing frequency, a pump's whine and a piezoelectric blower's drive tone are tonal by construction. A device with no moving parts contributes no mechanical tone, though it still has electrical noise to answer for.
YPlasma is early stage. The Y-Flow actuator on our thermal product page is in development and carries no automotive qualification today. Stating what the tests are is more useful than a claim:
It is not a bulk air mover. Ionic wind produces metres per second, not tens of metres per second, and electrical-to-fluid conversion for corona-based devices sits around 1 to 2 per cent [1]. If a box needs high volumetric flow, a fan is still the right answer, and the argument becomes whether the seal can be given up.
It also does not change what the housing can reject: conduction through the interface materials and convection off the outer surface still set the ceiling. An actuator raises internal transport, so it pays only when the stagnant air film is the bottleneck. If the interface material or the fin area is the bottleneck, fix that first.
And the wear mechanism does not vanish, it changes. Dielectric ageing under continuous electrical stress replaces bearing wear, and has to be characterised across the grades above, not assumed away.
The candidates are boxes where the internal air film is the limit and the seal is non-negotiable: chargers and DC-DC converters whose magnetics sit away from the cold wall, ADAS modules derating an SoC against a sealed lid, head units in a dashboard with no airflow and a customer listening for noise. It is the same argument in a different package as edge AI thermal management. Inverters are harder, being tied to the liquid loop at much higher heat flux, while battery thermal control and drag reduction are separate problems entirely. If internal air is where your sealed box is losing, talk to us.
What is sealed enclosure cooling? It is thermal management for electronics inside an ingress-protected, gasketed housing that cannot draw in outside air. Heat has to travel to the case wall by conduction, internal convection and radiation, then leave through the outer surface. It is the standard situation for automotive power electronics.
Why not just fit a fan inside an EV power electronics housing? An intake fan means vents, and vents mean losing the ingress protection that keeps water, salt and brake dust out. An internal recirculation fan keeps the seal but puts a bearing inside a box that will not be opened for fifteen years, and adds a tonal noise source to a cabin with no engine to mask it.
Does a plasma actuator work if no air enters or leaves the enclosure? Yes, because it does not ventilate. It moves the air already inside, stripping the boundary layer off hot components and driving internal air against the case wall. It adds no meaningful heat of its own, since the discharge is non-thermal and power draw is in the milliwatt range.
Is DBD plasma cooling automotive qualified? Not today. The technology is in development and carries no AEC-Q or vehicle-level qualification. Any thermal technology entering a vehicle has to clear component stress qualification, ISO 16750 mechanical and environmental testing, ISO 20653 ingress testing and CISPR 25 emissions limits before it can be specified.
What is the biggest technical obstacle for automotive use? Electromagnetic compatibility. A kilovolt-class AC drive is inherently a broadband RF source, and CISPR 25 protects on-board receivers from 150 kHz to 5925 MHz. Enclosure shielding, waveform design and cable routing all help, but compliance has to be demonstrated in a test chamber.