Posts By: Jeffrey Jenkins

A closer look at advances in power PCBs

In just the last few years there have been some major improvements in printed circuit board technology that are especially relevant to power electronics. Arguably the most important of the recent advances is the development of new board substrates that can withstand higher temperatures, along with metal cores for improved heat transfer, and the ability… Read more »

A closer look at current sensors in EVs

Pretty much every electronic circuit that handles significant power utilizes some means of measuring current, whether to simply protect against overload or because it is a basic functional requirement. In this article we’ll cover some of the more common devices and circuit techniques for measuring current in the major subsystems of an EV, including when… Read more »

SiC vs GaN semiconductors for EV power converters: Tech Opinion

Just as engineers are starting to get used to the advantages (and quirks) of silicon carbide (SiC ) devices, another semiconductor material joins the fray: gallium nitride, or GaN. Though there are some superficial similarities between these two materials, and even some overlap in their areas of best use, it is my opinion that only… Read more »

A closer look at the losses in power semiconductors

A previous article examined loss mechanisms in traction motors, which tend to be the single biggest source of losses in a modern EV drivetrain. This time, the focus is on the various power semiconductors, as they are the next biggest source of losses. Also covered in brief are ways to mitigate these losses and design… Read more »

A closer look at the losses in EV motors

  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 »

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 »