Electric vehicles can really put electrical and electronic systems to the test, requiring high voltage and high power components that will deliver performance without destroying themselves.
In general, alternating-current [AC] electric motors deliver better performance than direct-current [DC] motors, depending on the application. On a factory floor, for example, a three-phase AC motor doesn’t require any special electronics to control it because the power supply is already three-phase. The AC motor is very flexible and performs well under varying conditions, speed and power controlled by both voltage and frequency modulation.
On the other hand, a DC motor will require an inverter to convert two- or three-phase AC to the DC motor. DC motors work well under constant drive situations, speed and power adjusted by voltage modulation.
In electric vehicles, the electric motor needs to perform under a variety of conditions, which makes AC motors the weapon of choice, but require inverter and control modules than convert DC battery power to three-phase AC to drive the motor. One particular electronic component, used in inverter and controller assemblies, is the capacitor. Typical capacitors run up to 105°F, which means that extensive cooling systems are necessary to keep them from overheating and self-destruction.
A new high-temperature capacitor has been developed at the National Physical Laboratory [NPL] that can withstand temperatures up to 400°F at close to normal efficiency without burning out. Tatiana Correia, NPL’s lead researcher on the project, says “The opportunities for electric vehicles are huge, both financially and environmentally, but they are currently being held back by a few technical issues. With this high temperature capacitor we believe we have solved an important one of those issues and will play a vital part in the move towards mass market electric vehicles.”