RegGuheert said:
lorenfb said:
RegGuheert said:
the costs of the drive electronics are likely dropping at a similar rate while simultaneously improving in performance.
What do you base this statement on? Are you guessing semiconductor costs, e.g. discrete (IGBT) and I.C.s,
dropping because of what (increased BEV volume)? And what performance improvement are you forecasting,
i.e. like the motor controller really needs a faster processor or multithreading?
You didn't forecast controller efficiency. Maybe the IGBT Vsat will be reduced by 50% because of a new semiconductor
process technology?
More guessing like for future FCEVs, right?
I'm not guessing. The technology to cut the losses in the drive electronics is already well-established in the power-electronics marketplace.
IGBTs have massive switching losses which cause excessive overall losses and limit the switching frequency of the inverter. By moving to twice the battery voltage (some companies are doing this already) and replacing the Si IGBTs with SiC MOSFETs, the efficiency of the inverter can go from 95% to 98% and allow for better performance at highway speeds (without the need for complex systems like are found in the Chevy Volt).
First, your efficiency improvement of 3% hardly justifies:
1. Doubling the existing and standard 360 - 400 volt EV battery system with additional higher voltage overall
component costs.
2. Re-designing well proven motor designs whether it's the Tesla induction motor or the Leaf's PM motor.
3. Using a more costly switching device (SiC MOSFET), 5-10X more costly than IGBT, and less capable in
switching inductive energy loads is hardly a good trade-off.
4. More complex drive electronics with SiC MOSFETs, (Vgs is greater than typical logic levels as with IGBT).
The "complex systems" found in the Volt are not the result of not using SiC MOSFETs, The Volt is just a hybrid
copy of the Prius using two motors, a generator, three clutches, and an ICE, hardly an overall efficient design
as what one finds in a BEV, e.g. Tesla/Leaf. Single BEV motor systems, e.g. the Leaf, have more than
acceptable efficiency numbers which are not compromised at highway speeds. Only when you have a very
heavy BEV, e.g. Tesla, cruising at high speeds as a performance vehicle does a single motor become less
efficient requiring the second motor. Improved motor controllers (SiC MOSFETs) will not significantly
improve efficiencies in that case.
The improved "performance" aspect mentioned in the previous post hasn't been described?
So let's not conflate nascent battery technology evolution with the more mature EV motor & drive controller
technology.