Sunday, May 26, 2024

Reference Design For 6.6kW Unidirectional On-Board Charger

The horizon of EV charging is illuminated by a 6.6kW OBC reference design, leveraging GaN’s potential for swift and efficient energy transfer.


The transition to electric vehicles (EVs) marks a revolutionary shift in the automotive sector, and with this change comes the imperative to address the challenges and intricacies of EV charging infrastructure. A pivotal component in this ecosystem is the on-board charger (OBC), responsible for converting alternating current (AC) from the grid to direct current (DC) to charge the vehicle’s battery. Specifically, a 6.6kW OBC has emerged as a significant player in this space. This power rating balances charging speed and infrastructure demand, providing consumers a relatively quick charging solution without overburdening residential and public electrical systems. VisIC Technologies has launched a 6.6kW unidirectional OBC reference design, VRD-UNIOBCV1M1, to simplify the design process.

The reference design highlights the ability of 22mΩ Power FET GaN transistors to improve OBC efficiency and amplify power density through elevated switching frequencies. The OBC incorporates six Gallium Nitride (GaN) devices with two in the Dual Boost Bridgeless Power Factor Correction (PFC) and four in the Full Bridge LLC (Inductor-Inductor-Capacitor) with diode rectification. The benefits of GaN lead to the downsizing of PFC inductors and the LLC transformer while ensuring low power losses and a reduced number of devices. Moreover, it demonstrates an efficient heat dissipation approach using an isolated top cooling solution.

The OBC boasts several features, including a high power density of 3kW/L and an efficiency rate of 96%. The charger can accommodate an input of 90V-264V/47-63Hz in a single phase and provides an output ranging from 240V to 420V. It can deliver power up to 6.6kW with a 20A current at its maximum capacity, using liquid cooling through a cold plate. For safety and functionality, the charger includes protections such as Input Under Voltage Protection (UVP), Over Voltage Protection (OVP), and Over Current Protection (OCP). Remarkably, it has a Power Factor (PF) at a full load of 0.99 and offers Load Constant Current (CC), Constant Voltage (CV), and Constant Resistance (CR) modes. Furthermore, the CANAnalyst has a Graphical User Interface (GUI) for streamlined control and monitoring.

Some of the key specifications of VisIC 22mOhm GaN are:

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  • Dimensions, mm: 230D x 170W x 60H
  • Weight: 4.5kg
  • Power: 6.6kW
  • Power density: 2.8kW/L
  • HV transistors count: 6

VisIC Technologies has tested this reference design. It comes with a Bill of Materials (BOM), schematics, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.

Nidhi Agarwal
Nidhi Agarwal
Nidhi Agarwal is a journalist at EFY. She is an Electronics and Communication Engineer with over five years of academic experience. Her expertise lies in working with development boards and IoT cloud. She enjoys writing as it enables her to share her knowledge and insights related to electronics, with like-minded techies.


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