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Most conversions have regenerative braking nowdays. Most AC motor controllers support regen as a basic feature. A lot of the old series-wound DC motor convers

by elihu 5y ago

Most conversions have regenerative braking nowdays. Most AC motor controllers support regen as a basic feature. A lot of the old series-wound DC motor conversions didn't have it because it was hard to do on that kind of motor (similar how it's hard to reverse; you have to flip the polarity of one set of leads but not the other, which requires a bunch of contactors or IGBTs or something). Where regen gets kind of complicated is that you generally need to turn regen off when someone slams on the brakes. Unless the traction control / antilock braking system knows how regen figures into its calculations and can apply the proper braking force to each wheel taking it into account. I don't know what OEM EVs typically do in that situation, but for conversions you usually just have a brake switch so that regen can be automatically disabled when you're actually braking.

galangalalgol 5y ago
What does the software industry look like for this stuff? I've got two decades of embedded c++ experience, some of which is safety critical. How much of automotive is offshored these days? Is it still mostly C and a bsp and a text editor, or is it gitlab and pipelines now?
- elihu 5y ago
  I don't know, I'm just familiar with what the motor controllers do because I'm trying to do an EV conversion. I would imagine that the people working on parts for the conversion market have a somewhat different development process than a regular auto manufacturer, in part because they're making things in low volume and in part because they just have to design generic reusable parts that do one thing properly. If you're building a whole car, you have to make sure everything works together as a cohesive whole. In some ways that would be easier because you know exactly what parts are being used together. I would hope that most of the safety-critical real-time software that controls a car's basic functions like braking and traction control and so on would be relatively simple and straightforward, but maybe that's too much to expect. My understanding of the way the auto industry works these days is that the major manufacturers are increasing dependent on a complicated network of 3rd-party parts suppliers, and I'd expect that to influence the character of the software stack somewhat.

by elihu 5y ago

galangalalgol 5y ago

What does the software industry look like for this stuff? I've got two decades of embedded c++ experience, some of which is safety critical. How much of automotive is offshored these days? Is it still mostly C and a bsp and a text editor, or is it gitlab and pipelines now?

elihu 5y ago
I don't know, I'm just familiar with what the motor controllers do because I'm trying to do an EV conversion. I would imagine that the people working on parts for the conversion market have a somewhat different development process than a regular auto manufacturer, in part because they're making things in low volume and in part because they just have to design generic reusable parts that do one thing properly. If you're building a whole car, you have to make sure everything works together as a cohesive whole. In some ways that would be easier because you know exactly what parts are being used together. I would hope that most of the safety-critical real-time software that controls a car's basic functions like braking and traction control and so on would be relatively simple and straightforward, but maybe that's too much to expect. My understanding of the way the auto industry works these days is that the major manufacturers are increasing dependent on a complicated network of 3rd-party parts suppliers, and I'd expect that to influence the character of the software stack somewhat.