Development of Powertrain Electronics in Hybrid and Electric Vehicles

Author: Ahad Ahmed Buksh
Further Information about the author

A securely connected self-drive car aims to reduce its global CO2 footprint. At the moment, a lot of efforts are put in by the automotive industry to manufacture cars for a greener environment. Besides, Tesla’s breakthrough of elegant EVs is motivating vehicle OEMs like BMW, Volkswagen, Nissan, and others to step more rapidly into the EV business. According to IHS, fuel-efficient technologies and increased electrification will help car OEMs to facilitate environmentally friendly cars. Nowadays, a substantial amount of work is done on the exhaust aftertreatment systems to improve the fuel efficiency. For internal combustion engines, there is an increasing trend away from traditional incumbent multi-port fuel injection systems towards gasoline direct injection systems. This is simply because direct injection system increases the fuel efficiency of a vehicle. The prevailing concepts in the engine and the exhaust aftertreatment systems for internal combustion engines (ICEs) require sensors for their operation. The increase in sensor content will have ECUs with more inputs and this will push the need for intelligent controllers with higher speed operation and embedded memory. According to IHS, start-stop systems or so called micro-hybrids will outset the development of vehicle electrification on a large scale. Such a system, in which the engine turns itself off when the car stops at a junction or stop light, can improve the fuel efficiency up to 10%. This technology is already widely adopted by the European market but will also gain momentum in North America and Asia as each recognizes the importance of fuel efficiency and lower CO2 emissions. Increased vehicle electrification requires an alternative to the gasoline technology for driving the engine with the same amount of power. Thus, IHS sees 48V board-net bus technology as the next milestone to enable green car. This technology will allow a car to have functions such as recuperation, boosting, and sailing. A function like boosting would be achieved by the combination of electric motors working in tandem with the conventional engine. For this reason, the 48V technology would typically require three ECUs: a motor inverter for converting AC into DC and vice-versa, a DC/DC converter for bi-directionality, and a battery management system for supplying the 48V to the bus. Propulsion systems for electric and hybrid vehicles demand, on average, ten times more semiconductor content than a conventional engine. DC/DC converters for this technology would have to comply with ASIL-C requirement. In order to meet ASIL-C, as many as 18 MOSFETs would be needed to act as safety switches. With the rising levels of voltage levels on batteries for HEV/EVs, switching the voltage levels becomes a critical task for the power management components. MOSFETs, IGBTs, and diodes are growing in number to perform the switching functions. The high and low side driver ICs are needed to drive currents for the relays, injectors, and the different valves. Eventually, IHS perceives the battery management solutions to have a significant bearing in the cost of HEV/EVs. For instance, high-end EV brands like Tesla house around 7000 cells as opposed to Nissan Leaf which typically has around 192 cells. The presentation will cover the topics described above and its impact on the powertrain semiconductor and system level. It will talk about the developments and factors which are driving the changes within the propulsion system designs. It will also highlight how the electronics are powering the hybrid/electric and fuel-efficient vehicles.Last but not the least, the evolution in electronics which is enabling innovative architectural changes in powertrain of hybrid and electric vehicles will be discussed as well.