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4kw BLDC hybrid system help

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Last seen: 3 years 7 months ago
Joined: 2019-01-08 16:41
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4kw BLDC hybrid system help

Hello all! I've been building small motors for years, and I want to try my hand at a hybrid, which lead me here. I'm very mechanically-inclined, but I'm very new to circuitry and computer science. I would love to get your thoughts on any modifications I could make to the v4.12 schematic to help solve some of the potential heating issues. I'm looking at a pre-fab Maytech VESC for this application that says it can handle 60V, 50A continuous, 240A spike, but don't really understand why some ESCs handle higher current than others beyond "having better parts." I need your help in understanding which parts to upgrade, which I can leave alone, and most importantly, how to keep the process fairly simple. I cannot write code, and I don't want to take time away from the rest of the project by focusing on this one aspect, but I'm not opposed to some properly-guided modifications to code. I'm looking for a middle ground between the full DIY, as many of you have undertaken, and a commercial plug-n-chug system.

Some brief system requirements:

60V, 70A continuous (it's a 4kw motor assisting an ~8kw ICE)

sensored (hall), and all the other features of the 3.3 firmware, including regenerative braking, safety features, etc


Thank you all in advance!

Last seen: 2 months 2 weeks ago
Joined: 2018-11-18 14:09
Posts: 83

Hello thardi10

there is a VESC6 with 300A at 75V available and even the smaller can handle 100A+ so that's my first advice.

The problem with current is always the internal resistance of the PCB (how much copper is used) and FETs called Rds(which has to be wasted somehow) + switching frequency (compare it to acceleration and braking on motors). As FETs get smaller from time to time the cooling surface is quite critical. The only surface to cool is the metal backplane of the FETs which is (on VESC V4) soldered and gets a bit of the heat to the PCB but that's really limited. The new VESC6 is done with so-called directFETs with their cooling side upside down so the real start to effective cooling.

I'm only a designer for Lithium chargers but nearly all ESCs from China are so overrated in their amperage or designed with no safety area (no SOA) so they tend to get killed quite fast. The VESC (in my opinion) is open and you could change the FETs or Cs or whatever so it fits you. Three years ago I've seen a design based on the VESC 4.x with 100V and 300A to power a boat motor with 20kW so it's capable to do business.

But I'd opt for the bigger VESC 6.x as they can already what you are asking for AND it's standard no custom (=easy to get & replace when needed). Frank has surely more info about them.



Pedelec usage in combination with a GoldenMotor MagicPie3 BLDC

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Joined: 2016-12-27 20:19
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Sounds like the VESC 6 could handle that. At 70A continuous you will need to attach the VESC 6 to a proper heat sink.

Click on Hardware and you will get a direct link to the VESC six and VESC 75/300