As vehicle electronic content proliferates, electronic component quality and reliability must improve to maximize vehicle performance and reduce warranty issues. While component quality and reliability were always important, the new trend towards hybrid (HEV/PHEV) vehicles and battery-powered electric vehicles (BPEV) adds a new dimension.
Older gas power vehicles had only a minimum of electronics - an electronic component failure may have stopped the radio from working but not prevent anyone from getting home ok. Simple engine control functions where added, to improve engine efficiency and fuel economy. This created the need for quality and reliable components as a single component failure could stop the engine from functioning.
Today, with vehicles that are almost completely controlled by electronics, drivers can face different kinds of reliability risks. Typical, the electronics begin their work when a driver walks up to the car and the passive entry system unlocks it. The interrogator pings the key to allow you to start the car with a press of a button. Numerous power supply, analog and microcontrollers circuits start up and control your engine, transmission and almost everything else in the vehicle. Then there are additional feature systems to power, including navigation, anti-lock brakes, cruise control radars, infotainment electronics, etc, etc.
Reliability standards (ISO/TS16949) in the harsh automotive environment are vital because the average car today requires an electrical power processing capability of 250 to 1,500W, a number that is increasing rapidly due to the high power electrical system required in vehicles for powering the car or truck, and also for entertainment and efficiency. Because a vehicle battery is a relatively unregulated low voltage source, it requires a regulated high voltage DC-DC system, which in most cases means a boost DC-DC converter using a multiphase boost architecture.
As an example, consider the simple starting and stopping functions. In the automotive environment, a start/stop system automatically shuts down and restarts the internal combustion engine to reduce the amount of time the engine spends idling, thereby improving the fuel economy. This is most advantageous for vehicles that spend significant amounts of time in traffic jams, requiring frequent start and stop. During the starting period, the battery undergoes what is known as voltage cranking deep, which can be as low as 6V. In order to protect all the electronics connected to the battery bus, the bus line voltage has to be protected from seeing the battery-cranking transient.
One method to solve this issue is by having a regulated multiphase boost DC-DC converter temporally connected between the battery and voltage bus in order to overcome the dip when a cranking transient happens. In this configuration, when the battery voltage is below an 11.5V threshold, the battery voltage will be boosted by the multiphase boost DC-DC to provide a stable bus voltage.
For the complete article, which describes the circuitry involved with the start/stop system, infotainment power electronics protection, and how the multiphase boost converter works onr hybrid, electric, and fuel cell vehicles, click here, courtesy of Automotive Designline Europe.