Power conversion challenges in electric vehicles
On-board charger (OBC) systems are a major concern for every designer and manufacturer of electric vehicles. The technical requirements are easy enough to state: the OBC is a multi-stage power conversion system that takes AC power from the mains and converts it to a controlled DC supply for charging the traction battery, while providing isolation to protect the user from hazardous voltages, either from the mains or from the battery. Meeting these requirements in a practical and commercially viable design, however, presents many challenges relating to cost, reliability, size and efficiency.
Challenges of power conversion
Every single component in a vehicle adds to cost and every increase in cost makes the vehicle less competitive in the marketplace. That means low component count is paramount – but it’s not the only contributor to cost. Design time is also costly, as is the time and effort involved in achieving qualification and certification for new designs. So working with a supplier that can provide support in these areas offers decisive advantages.
While reducing manufacturing costs is a priority for every vehicle manufacturer, reliability is also a key issue. Components with a high failure rate quickly lead to spiralling warranty costs and, even worse, to brand damage that’s difficult and expensive to repair. Should there be safety implications, there’s also the risk of industry regulators imposing severe penalties. Low component count helps here too, since fewer components means fewer potential points of failure.
Size and weight are always concerns for designers of the systems used in electric vehicles. Size because every cubic centimetre occupied by equipment reduces the usable space in the vehicle and weight because added weight reduces the range and overall economy. Once more, low component count – and simplified designs – make life easier by paving the way for smaller, lighter systems.
Underpinning all of these requirements for OBCs is the need for efficiency. Not only is economical use of energy one of the primary motivations for the development of electric vehicles, high efficiency in OBC power conversion brings two other invaluable benefits: shorter battery charging times and less unwanted heat generation. The reduced heating means lower OBC operating temperatures which prolongs operating life and reduces the risk of failure.
Cost, reliability, size and weight, efficiency: the challenges of developing an optimised OBC for an electric vehicle are apparently diverse but in reality, a single innovation provides designers and manufacturers with the key to addressing all of them. That innovation is the Power-ThruTM technology which is exclusively used in gate drivers from Heyday Integrated Circuits.
With Heyday gate drivers, the power needed for driving the gates of the power semiconductors used in OBCs is transferred by a novel magnetic coupling device within the integrated circuit itself – no auxiliary power supply is needed and the coupling provides complete isolation. This means an impressive reduction in component count, module size and cost, coupled with enhanced efficiency. Further, overall simplification dramatically reduces the time needed for module design and development.
To find out more, watch Heyday webinar on OBC and inverter applications: