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Importance of on-board charger isolation

wallpapers News 2021-05-17
About EV on-board charger
On-board Chargers (OBCs) convert AC power from the external charging source to DC voltage, which is used to charge the battery pack in the vehicle. OBCS also has additional features, including rate monitoring and protection. The industry charges for OBC systems are shown in the table below. AC level 2 OBC and some level 1 systems need to be isolated. With DC quick charger, plug directly into quick charging connector, OBC bypass.
Importance of on-board charger isolation
The on-board charger uses an AC input source that is converted to HVDC by a rectifier and provides power factor correction (PFC). The resulting DC signal is cut into a switching square wave that drives the transformer to produce the desired output DC voltage. The chopping of the input signal is accomplished using isolated gate drivers such as SI8239X, SI823X, SI823HX and SI827X.
Under the control of an additional isolated gate driver, the output voltage is filtered to the final DC voltage using a synchronous field-effect tube. The output voltage can be monitored using an isolated analog sensor (e.g., SI892X) to provide closed-loop feedback to the system controller
The entire on-board chargers system can be monitored through an isolated CAN bus. CAN is isolated using digital isolators and digital isolators integrated with DC/DC power converters, including SI86XX and SI88XX.
On-board charging will remain an important aspect of all-electric vehicles for the foreseeable future, and while it is slower than a fast DC charger, it offers more flexibility to charge (or charge) the car from a common power outlet. However, when the vehicle is in motion, the OBC has no function, if it is too big or too heavy, then all it does is reduce the range.
Thus, the challenge for designers was to design OBCs not only to be operationally efficient but also to be small and lightweight. They must be able to cope with the rigors of the automotive environment (heat, vibration, etc.) and be able to meet the aggressive requirements of the car manufacturer at a cost point.
While passive components may be simple in nature, they play a key role in helping designers meet these challenging goals, and the market is rapidly evolving to meet the growing demand in this area. The options on offer are vast, and the right choice is key.