In the bad old days when the only batteries suitable for traction applications were flooded lead-acid and Ni-Cd types, the battery was the least efficient component of an EV powertrain, routinely delivering back only 50-70% of the amp-hours that went into charging it (aka the Coulometric efficiency). When you knew you were going to… Read more »
Posts By: Jeffrey Jenkins
Top causes of failure in power semiconductors
All electronic devices eventually die, and the failure can be quite spectacular if suitable foresight and care was not employed during the design and construction phases, especially if the device handles high power or is supplied by a large battery. It should go without saying that both conditions apply to much of the electronics inside… Read more »
Regenerative braking: A closer look at the methods and limits of regen
All motors are generators, the old saying goes, with the caveat that few types are equally good at both modes of operation, and some are downright awful as generators (a classic example being the single-phase shaded pole induction type, used in myriad small appliances the world over). Fortunately, both types of AC motor commonly used… Read more »
A closer look at DC-DC converters
As far as we know, all EVs in production by major automakers use a conventional lead-acid battery for the 12 V system (surprising, but true – more on why in a bit) and this battery needs charging, just as it does in an ICE vehicle. While you could hang an alternator off the traction motor… Read more »
A closer look at film capacitors
Plastic film capacitors relentlessly continue to take over many of the duties in EV power electronics that were once performed by the venerable aluminum electrolytic type, mainly because film capacitors exhibit much lower losses and have a much longer operational lifespan, especially at ambient temperatures in the 75-85° C range. The tradeoff is that film… Read more »
A closer look at contactors
Contactors may not be the sexiest component in an EV, but they are critical both for safety and general functioning. Basically a heavier-duty version of the relay, a contactor is used to switch power to any of the loads supplied by the traction battery in an EV. The motor drive, the heating and cooling systems,… Read more »
A closer look at energy consumption in EVs
When it comes to factors that affect energy consumption in EVs, the big kahunas are weight and wind resistance (aka CdA), but there are other factors that can have a surprisingly outsized effect and that tend to be overlooked, such as the use of climate control (AC, of course, but especially heat). Conversely, one factor… Read more »
A closer look at power factor correction
Power Factor Correction (PFC) used to be something that electronics manufacturers only grudgingly added to a product – usually because of complaints about breakers tripping prematurely, or to meet regulatory requirements in the EU – but these days PFC is showing up in more and more products. While one should never underestimate the ability of… Read more »
A closer look at wire in EVs
Wire is not the most glamorous of components, but it is the enabler of our modern society – especially of our even more modern mode of transport, the EV – and a surprising amount of technology and engineering goes into making, selecting and using wire. How wire is made The modern method of manufacturing copper… Read more »
A closer look at rare earth permanent magnets
Rare earth magnets have gotten a lot of coverage in the EV press over the years for being expensive – especially back in 2011 when a supply disruption in China sent the prices up anywhere from fivefold for neodymium to 20-fold for dysprosium over the course of a few months – yet they are still… Read more »