On-board chargers use compact power conversion stages that place demanding requirements on high frequency transformers. The transformer may need to support isolation, high efficiency, controlled leakage inductance, low winding capacitance, stable thermal behavior, and repeatable production. A standard transformer is rarely the best answer when charger size and reliability both matter.
BaoHui Tech manufactures custom high frequency transformers, power transformers, inductors, filters, and magnetic components for chargers, inverters, UPS systems, industrial power supplies, and renewable energy equipment. For on-board charger projects, transformer design should be linked closely to the converter topology and certification requirements.
Start from the converter stage
Many on-board chargers use resonant or phase-shifted power stages where the transformer directly affects efficiency and operating range. Turns ratio, magnetizing inductance, leakage inductance, winding resistance, and capacitance all influence system behavior. The transformer manufacturer should know the topology, input voltage range, output voltage range, switching frequency, and power level before sample design.
Isolation must be designed early
Chargers require reliable isolation between high-voltage battery circuits, grid-side circuits, and control electronics. Creepage, clearance, hipot voltage, insulation material, and winding separation should be defined at the start. Adding insulation later can change leakage inductance, winding capacitance, size, and thermal behavior.
Thermal design is a packaging issue
On-board chargers are space-constrained and may operate near heat sinks, power modules, bus bars, and sealed housings. Transformer temperature rise must be tested under realistic enclosure and load conditions. Core loss, copper loss, proximity effect, and potting or impregnation choices all affect the final result.
EMI behavior is connected to winding structure
High-voltage switching creates common-mode noise paths through transformer capacitance. Winding order, shielding, interleaving, grounding, and filter selection must be coordinated. A transformer with excellent efficiency can still create EMI problems if capacitance and layout are ignored.
Production control matters
Charger transformer performance should be repeatable across batches. Drawings, material lists, winding instructions, and test limits should include inductance, leakage inductance, DCR, turns ratio, hipot, and visual inspection requirements.
FAQ
What transformer is used in an on-board charger?
Many on-board chargers use custom high frequency isolation transformers in resonant or DC-DC conversion stages, along with inductors and EMI filters.
Can BaoHui Tech manufacture charger transformers?
Yes. BaoHui Tech supports custom high frequency transformer manufacturing for charger, inverter, UPS, and power electronics applications.
A reliable on-board charger transformer is built around topology, isolation, thermal margin, EMI behavior, and production repeatability.