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ORNL Researchers Modify Plug-in Hybrid Electric Traction Drive Power Electronics to Function as On-Board Charger; Mobile Power Generation and V2G Support as Well

The approach for hybrids using multiple inverters and motors (left) and a single inverter and motor (right). Additional components are shown in red. Each INV/CONV functions as a switch leg while splitting the current among the 6 switches. Source: Su. Click to enlarge.

Researchers at the Department of Energy’s Oak Ridge National Laboratory have designed, fabricated and demonstrated a PHEV traction drive power electronics system that functions as the on-board charger, and that also provides significant mobile power generation and vehicle-to-grid support capabilities.

The system comprises a 55 kW motor inverter and a 30 kW generator inverter that is capable of Level 1 and Level 2 charging rates (1.8 ~ 19.2 kW), mobile power generation of up to 20 kW, and vehicle-to-grid support. The system, if applied in a vehicle, could represent up to a 90% reduction in cost and volume compared to on-board standalone battery chargers.

The new technology eliminates the separate charging mechanism typically used in PHEVs, reducing both cost and volume under the hood. The PHEV’s traction drive system is used to charge the battery, power the vehicle and enable its mobile energy source capabilities.

—Dr. Gui-Jia Su, Senior R&D Staff Member, Lead Engineer of Power Electronics

FY08 prototype test setup. Source: Su. Click to enlarge.

The approach, said Su, is to utilize on-board inverters and motors for charging/sourcing; no additional switch or filter inductor components are required. “It’s basically software and pulling some more wire,” Su said.

The two motors need not be rated at the same power level, and the approach can be applied to a range of motor/power electronics capabilities. The current rating of the switches and the motors is what determines the charging rate.

Testing of the charging system showed a high efficiency of 92~98% vs. 80~85% for commercial, off-the-shelf (COTS) charges. The system support a power factor of >98% and low harmonic distortion.

Su said that several companies, including Raser and MBTech, have expressed interest in the system.




A very smart idea for less on-board equipment, less weight and more efficiency.

Another step in favour of future BEVs.


A natural gas powered range extender also becomes and combined heat and power unit for the home.

Nat Pearre

The almost 15 year old AC-150 power electronics unit from AC Propulsion does all this. Not that more competition isn't a good thing, but it's not all that groundbreaking.


Even if "The almost 15 year old AC-150 power electronics unit from AC Propulsion . . " had NOT done all this, it is an insult to our intelligence and all engineers that are developing EVs, to claim that this obvious synergism would provide "up to a 90% reduction in cost and volume compared to on-board standalone battery chargers.." or that no one has thought of this in multitudes of variations.


But for those that come to learn , thank you.

Stan Peterson

Ever wonder how Volt Gen II will be cheaper? Here is an elementary but concrete example...

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