High-Power Rectifiers for DC Fast Charging Shorten EV Charge Times

OmniOn Power, formerly ABB Power Conversion, is releasing high-power EV100 and EV101 rectifiers for the rapidly growing EV charging market. The 30 kW supplies are the company’s first-ever products designed specifically for EV fast-charging requirements and can accommodate both standard 400 V and emerging 1000 V powertrain bus voltages.   

 

Charging an EV with a Level 3 DC fast-charger. Image used courtesy of EVBox

 

The high-power rectifiers efficiently convert nominal three-phase AC line power (400/480 Vac) to high-voltage DC to rapidly replenish EV batteries. High and low output voltage modes allow a single supply to support output voltages ranging from 150 to 1000 VDC.

Each rectifier is enclosed in a self-contained, air-cooled chassis that measures 13.23 x 3.30 x 17.25 inches and fits in a 19-inch rack mount for easy installation. CAN automotive protocols are supported to facilitate system communications.    

 

EV100/EV101 rectifiers for EV fast charging. Image used courtesy of OmniOn Power

 

OmniOn Power, ABB's former Power Conversion division, was re-branded under its new name earlier this month following the group’s $505 million acquisition by AcBel Polytech Inc. this past summer. 

Need for Reliable and Accessible EV Charging

According to Gopal Mitra, Industrial Segment Leader for OmniOn Power, access to reliable charging and the ability to charge vehicles quickly are the two biggest hurdles to the broader adoption of electric vehicle technology.   

With the EV10x rectifiers, OmniOn Power addresses both of these issues, offering a supply with sufficient power and scalability to meet the needs of EV fast-charging and designed for reliability to maximize the operational up-time of EV supply equipment. 

OmniOn Power has drawn upon the company’s years of experience in maintaining and servicing DC fast-charging infrastructure to achieve these goals for its rectifiers.  
 

Rectifying Line Power in a DC Fast-Charger

With DC fast-charging (Level 3), the EV charger bypasses the onboard charger and charges the vehicle’s battery directly with high-voltage DC (up to 1000 V) via the battery bus. 

In a DC fast-charger, the AC rectifier and power factor correction (PFC) circuit converts three-phase AC line power to DC. This is typically followed by an isolated DC-DC conversion stage that generates the well-conditioned DC output voltage needed for vehicle charging. 

Level 3 fast chargers can deliver several hundred watts of power, so the rectification, PFC, and power conversion circuits within these units must accommodate these power levels.  

 

DC fast-charger functional schematic. Image used courtesy of onsemi

 

Operation of the EV100 and EV101

The EV100/EV101 rectifiers receive three-phase, 60 Hz AC line power at 260 Vac to 530 Vac and convert this to 30 kW of DC output power at 150 to 1000 VDC. To achieve its high levels of efficiency, the supply most likely uses active rectification and PFC. 

Each rectifier unit can maintain 30 kW of constant power at voltages as low as 300 VDC with a maximum output current capacity of 100 Adc.

For higher power chargers, up to twelve rectifier units may be used in parallel to deliver a total power capacity of 360 kW at conversion efficiencies of up to 96%. Most EV batteries can be completely charged at these power levels in under one hour.   

CAN automotive protocols facilitate communications within the DC fast-charging system and between the fast-charger and EV. Effective communications help ensure the vehicle's fast, safe, and reliable charging.  

While the EV100/EV101 rectifiers are the first OmniOn Power products designed specifically for the fast-growing EV charging market, they leverage expertise developed through years of work designing power systems for the wireless infrastructure and data center markets.  

 

Safety Considerations

Safety is a key priority with the high power densities associated with DC fast chargers. The EV100/EV101 are designed with safety in mind and comply with the latest EV supply equipment safety standards, including UL, VDE, and CE safety requirements.

For jurisdictions that require an electromechanical emergency shutdown capability, the EV101H3N1K incorporates a discrete emergency power-off circuit for an added layer of protection.