An EV charger looks like a box with a cable. Inside, it is a power-electronics problem wrapped in a safety problem wrapped in a connectivity problem. Grid AC has to become a clean, isolated, metered charge the vehicle will accept — and a back office has to supervise it.
At the input, grid AC is drawn through power-factor correction, which shapes the current to stay in phase with the voltage so the charger is a well-behaved load that does not distort the supply or waste capacity. From there a DC-DC conversion stage sets the voltage and current the battery wants, under the vehicle’s control.
In DC fast charging the charger does the heavy conversion and feeds DC straight to the pack; in AC charging the vehicle’s on-board charger does it and the wall unit mostly switches and meters. Either way, efficiency here is money and heat: every percentage point lost becomes waste heat the enclosure has to remove.
Galvanic isolation separates the vehicle and its user from the grid, so a fault on one side cannot become a hazard on the other. Around it sits a layer of protection: residual-current detection, insulation monitoring, over-current and over-temperature limits, and the control-pilot handshake that confirms a safe connection before any power flows.
This is the part that turns a power supply into a product people can touch. It is heavily standardised, it is tested hard, and it is where a lot of the real engineering time goes — because the failure modes are safety failures, not just performance ones.
A charger has to measure what it delivered accurately enough to bill, and report it. That means revenue-grade metering and a connection to a central system — usually over OCPP, the open protocol that lets a charge point talk to any compliant back-office platform for authorisation, pricing, remote start/stop, firmware updates and fault reporting.
Delivered through a CCS or Type 2 connector, the charge session is negotiated between vehicle and charger and supervised from the cloud. Connectivity turns a dumb socket into managed infrastructure — and makes firmware, security and over-the-air update part of the design from day one.
The hard parts of an EV charger are rarely the headline power number. They are thermal design that holds efficiency across a hot day, isolation and protection that pass certification the first time, metering accurate enough to bill, and a connectivity and firmware stack that stays secure and updatable in the field for a decade.
We treat a charger as that whole system — the power electronics, the safety and isolation, the metering, and the embedded and connectivity stack behind OCPP — engineered together, because the trade-offs between them are the product.
In AC charging the wall unit mostly switches and meters, and the vehicle's on-board charger converts AC to DC for the battery. In DC fast charging the charger itself does the AC-to-DC conversion and feeds DC straight to the pack, which is why DC chargers are larger and more powerful.
It shapes the input current to stay in phase with the grid voltage, so the charger draws power cleanly without distorting the supply or wasting capacity. It makes the charger a well-behaved load, which is required at the power levels chargers operate at.
Isolation electrically separates the vehicle and user from the grid so a fault on one side cannot become a hazard on the other. It is a core safety requirement, surrounded by residual-current detection, insulation monitoring and the control-pilot handshake.
The Open Charge Point Protocol: an open standard that lets a charge point communicate with any compliant central management system for authorisation, pricing, remote control, firmware updates and fault reporting. It stops operators being locked to one vendor's back office.
Not the peak power figure, but thermal design that sustains efficiency, isolation and protection that certify first time, billing-grade metering, and a secure, updatable connectivity and firmware stack that must last in the field for years. The trade-offs between these are the engineering.
Commonly CCS (Combined Charging System) for DC fast charging and Type 2 for AC charging in many regions. The connector carries both the power and the signalling that negotiates and supervises the charge session between vehicle and charger.
Power electronics, isolation and safety, billing-grade metering and a secure OCPP connectivity stack — engineered as one system. Tell us the power level, the standards and the environment.