Battery Chargers

We provide on-board battery chargers (AC/DC converters) in the range from 3.7 to 22 kW for plug-in and pure electric vehicles. Moreover, we provide inductive power transmission battery charger systems. Depending on the requirements of our industrial customers, the focus may be overall power density, extreme compact design, EMC, high efficiency, or special functions like bidirectional operation mode used for vehicle to grid (V2G) scenarios or providing an on-board high power AC plug.

Current techniques and future research topics are always central in our development, leading to power electronic components and prototype systems showing the performance of modern power semiconductors.

While the majority of projects are non-disclosure, some samples and open research projects are shown below.

Modular 3.6 kW On Board Charger

Up to 22 kW in three phase configuration


  • Galvanically isolated OBC Module
  • Ultra Low Volume of 1 dm³
  • High Power Density of 3,6 kW/dm³
  • Directly stackable up to 6 modules and 22 kW
  • Digitally Controlled

3.6 kW OBC withopen case


Download Product Sheet as PDF:

Core materials are made by Hitachi

  • Amorphous PFC Core (HLM50)
  • Ferrite Transformer Core (ML29D)
  • FINEMET® CM-chokes



This isolated AC/DC converter combines a good efficiency with a very small volume and therefore a high power density. It was developed using
the newest high performance Materials provided by Hitachi Metals. It contains a totem pole PFC stage and a full bridge resonant converter both
using 900 V SiC Mosfets. All semiconductors are mounted on an Insulated Metal Substrate (IMS). This provides a good thermal connection to the coolant underneath and also an easy way for assembly.
The total system consist of only three boards. PFC stage is digital controlled and runs at a switching frequency of 120 kHz.
The coil consist of a gapless amorphous powder ring core with a solid copper winding.
The resonant converter is working at a fixed switching frequency of 250 kHz. Its transformer is built of low loss ferrite material with litz wire and has a significant leakage inductance. Together with ceramic capacitors it forms up the resonant tank of the LLC converter.
Both, AC and DC EMI filters are buildup out of FINEMET® material.

Technical Data

  Min Max
vIN 80 Vrms 265 Vrms
300 V 450 V
P  (p. Module) 0 kW 3.66 kW
eFFICIENCY   95.4 %
dIMENSIONS 11,2 x 21,1x4,2 cm

3.7 kW Battery Charger for automotive applications

With a volume of less than 4 liters and an efficiency of 95% the presented 3.7 kW Battery Charger is designed for auto-motive applications. The charger offers a galvanic isolation of the high voltagebattery regarding the AC-mains whatmeans it is suitable to Typ-A RCDs and is supporting charging mode 2 and mode 3 according DIN EN 61851-1 includingcontrol of Typ 2 receptacle with LED-ringand lock.

Due to a 2-stage design approach with PFC, DC-link, and insulatingDC/DC converter, a constant chargingcurrent is available and the battery outputvoltage range can be customized. Thecharger is controllable via CAN communi-cation and it can be cooled via integratedwater cooling channels or by an external attached air cooled system. The 3.7 kW Battery Charger is the smallest chargersystem within a broad on-board chargerproduct line for 3.7 kW, 7.4 kW, 11 kW and 22 kW demands which are all basedon a modular circuit design approach.

Technical Data

Galvanic Isolation yes
max. input power @ 230 VAC, 16 A 3.7 kW
Battery Voltage Range 315 V - 395 V
Input Voltage range 115 V - 230 Veff
Efficiency Max 95.3 %, Typ. 95 %
Dimensions 275 mm x 185 mm x 78 mm
Volume < 4 l
Protection degree IP 67
Supply Coltage Range 8 V - 16 V