Renault’s bidirectional charger to drive 30% uptick in energy efficiency
The French Alternative Energies and Atomic Energy Commission (CEA) and Renault Group have jointly developed an on-board bidirectional EV charger, which reduces energy loss by 30%.
For bidirectionality, electronic power converter architecture is directly integrated into the Electric Vehicle’s (EV’s) charger and is the result of up to three years research and the subject of 11 joint patents.
In addition to enabling bidirectional energy flow – storing and discharging energy from the electricity network – the power converter, according to Renault, will reduce energy losses by 30%, improve the EV’s recharging time and guarantee the battery’s durability.
V2G capability
The converter architecture offers a charging capacity of up to 22kW in three-phase mode, allowing for faster charging of the vehicle while ensuring the durability of the battery.
It also allows the charger to be bidirectional, enabling Vehicle to Grid (V2G) capacity, where energy stored in the battery can be fed back into the grid or used to supply the energy needs of an autonomous house, provided that the house is equipped with a bidirectional meter.
The solution is compatible with the electromagnetic compatibility (EMC) standards of the networks and the car.
Jean-François Salessy, vice-president advanced engineering, Renault Group explains, “This project…opens up strong prospects for power electronics, which is a real challenge in the electric vehicle, in order to make the best use of the batteries’ capacities. With bidirectional charging, the vehicle serves the electrical network and enables the end consumer to reduce energy costs.”
When such technology is widespread, the grid management and energy saving potentials are immense. When energy supply in a given area is higher than demand, smart devices and EVs can charge up. And under a bidirectional system, the inverse is true. When demand exceeds supply, charged up tech can discharge onto the grid, providing an efficient method of coordinating load management.
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Materials
The CEA and Renault Group R&D teams combined their acumen in the field of on-board power electronics, in particular in the field of wide band-gap semiconductor materials, whether in Gallium Nitride (GaN) or Silicon Carbide (SiC).
The new architecture makes it possible to reduce energy losses by 30% during conversion, and to reduce heating by the same amount, making it easier to cool the conversion system.
In addition, the engineers’ work to optimise the active (semiconductors) and passive (capacitors and wound inductive components) components has enabled a reduction in the volume and cost of the charger.
Thanks to the use of ferrite materials, dedicated to high frequency, and a shaping injection process called “Power Injection Molding”, the converter has also become more compact.
“The use of innovative materials with joint Renault Group – CEA patents on the charger made it possible to manufacture the dedicated transformer, which is a key component in this type of development, as it allows for a reduction in volume with performance that goes beyond the state of the art”, commented François Legalland, CEO of CEA-Liten.
