EV-FEATURE
Next-Generation Electric Vehicles Demand the Safety of High-Reliability Circuit Protection Next-generation electric vehicles incorporate an array of complex and highly compact circuitry, and engineering design that can deliver both innovation and human safety remains a major challenge. It’s not simply a question of sophisticated microprocessor technology. These vehicles also implement the latest in EV onboard charging techniques. Designers need to ensure that the possibility of overloads, transients, and electrostatic discharge is taken into account, with safety and reliability the over-arching criteria, all the way through from concept to timing closure and sign-off. Designers must plan for contingency, and this whitepaper addresses seven mission-critical onboard charging circuits that provide recommendations for both circuit protection and efficient power control.
Moreover, the deployment of both an onboard charger and AC power line can result in the generation of both transients and overloads. The charger’s circuits demand adequate protection, and communications circuits must also be able to survive ESD transients, in order to avoid data corruption. Add to the design engineers will need to minimize power consumption, allowing the battery charge time to be as short as possible. The AC line voltage, converted to DC, charges the main battery pack to within an output range of of 300–500 volts. Key challenge for designers is meeting consumer demand for faster charging, which requires high-power charging circuitry, including three-phase designs. A single-phase circuit is shown in Figure 2. Each circuit block indicates the suggested protection components plus any components needed to optimize the charger’s efficiency.
Figure 1, above, is an overview of the electronic systems typical of a hybrid vehicle where the combination of internal combustion engine (ICE) and electric drive effectively multiplies potential transients by an order of magnitude, presenting the designer with a special challenge.
42 11 | 2021 BISinfotech
