EV Charging Control Module
A 22 kW AC charge controller with residual current detection, PLC communication and grid-code compliant load management.
- Client
- Voltix Mobility
- Sector
- Energy & Power
- Year
- 2024
- Duration
- 30 weeks
- Layers
- 4
- Board size
- 140 × 90 mm
- Placements
- 268
- IPC class
- Class 2
Stack-up: 2.0 mm FR-4 Tg170, 2 oz outer, reinforced isolation slots
The challenge
Detecting 6 mA of DC residual current per IEC 62955 while sitting beside three 32 A conductors carrying switching noise, and running ISO 15118 power-line communication over the same cable. Two earlier prototypes had produced nuisance trips at roughly one per fourteen days.
Our approach
The residual current sensor was moved to a fluxgate type with a differential drive and given its own shielded compartment with a slotted, guarded ground. The PLC coupling network was redesigned with a common-mode choke and the injection point relocated away from the sensor aperture. Firmware added a coherent averaging window synchronised to the mains cycle so switching transients, which are not mains-coherent, average out rather than accumulating.
The outcome
Nuisance trips fell to zero across a 90-day field trial on twelve units. The module met IEC 62955 6 mA DC detection with margin and passed EN 61851-21-2 EMC on the first attempt. It has since shipped in three of the client's product lines.
Measured outcome
0in 90 days
Nuisance trips
6mA
DC residual detection
1
EMC attempts
3
Product lines shipped
The trip was a measurement problem, not a threshold problem
Raising the trip threshold would have failed the standard. The real issue was that switching transients were being integrated as though they were residual current. Synchronising the averaging window to the mains cycle discriminates between the two without touching sensitivity.
Shielding the sensor properly
A fluxgate sensor is only as good as its magnetic environment. Its own compartment, a guarded slot in the ground plane and a relocated PLC injection point removed the coupling that the previous revisions had been fighting in firmware.
From the bench
Pre-compliance probing on revision A found the coupling path early.
Two suppliers had told us the nuisance trips were inherent to the sensor. Anode reframed it as a measurement window problem and we have had zero trips in ninety days of field trial.
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