Bi-directional charger inverter : Combining multiple functionalities into one box

January 3 2018

Since the inception of electric vehicles, chargers have played a key role recharging the battery and ensuring that it is always operating safely and maintained in a good condition to deliver the best performance. Chargers, vehicles and batteries were all simple enough in the early stages of the technology, but as battery systems and charging safety requirements have become more complex, the need for more sophisticated charging solutions has emerged.

Electrification of commercial vehicles accelerated the transition from alternator-powered auxiliaries, to components that operated at higher voltages and fed directly from the EV’s high-voltage battery using DC-to-AC inverters.

Additionally, onboard chargers with bi-directional functionalities have recently become of interest to fleet operators and vehicle manufacturers thanks to their compatibility with vehicle-to-grid (V2G) applications. These applications are expected to be standardized in the future – as power utilities and consumers look at various ways to optimize energy consumption during peak demand hours in order to reduce loads on the power grid and avoid purchasing electricity when the rates are at their highest.

TM4 has always been at the forefront of electric and hybrid powertrain development. The company’s expertise in the field has enabled the development of a compact bi-directional charger that provides not only battery charging functionality but also auxiliary power supply during vehicle operation – using the same power electronic modules to supply a configurable voltage and frequency output to auxiliary devices.

Above: charger mode

In charger mode, the TM4 BCI20 converts AC to DC power to efficiently charge the electric vehicle’s battery. It is designed to use the full current range from the AC mains supply, as defined in SAE J1772, for a maximum charge power of 18kW on 240V AC.


Above: inverter mode

When the vehicle is in use, the unit becomes a dual inverter, which converts stored onboard energy from the electric vehicle battery to AC power. Its two independent three-phase outputs of 9kVA can each be used to power various loads, including pumps, HVACs, and so on. The charger, combined with two inverter outputs, simplifies vehicle integration and saves weight and space by combining multiple functionalities in one box.

The BCI20 satisfies the IP67 rating for reliable operation in harsh underhood vehicle environments. Its aluminum enclosure is sealed against dust, sand and water. It is compact and lightweight, and allows for a flexible installation in multiple mounting locations within the vehicle.

Over time, TM4 will expand this new series of products and offer the North American and European markets single-phase and three-phase bi-directional charger-inverters, available in either 450V DC or 750V DC voltage ranges.

Maggie Parisé
Latest posts by Maggie Parisé (see all)

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