EBMX X-9000 power stage macro view

[@elilior]

Hi I need to fix my x-9000 controller

[@MrDehicka]

1. At this current levels such big gaps are not acceptable. 7mm wide trace with just 3mm length of 70um copper will have about 0.14mOhm resistance @ 100C. And you have four gaps on each half-bridge. So it is more than a half FET Rds(ON) itself. KO is much worth, but it not the excuse to do it better be better, it not a cheap controller. 2. Thermistors are placed incorrectly. They are very close to the copper phase bar with high thermal mass/conductivity and will not react quickly to the FETs temperature rise. 3. Not 100% sure, but the phase bars are not press fit. It is just two separate parts. Press fit will not have such visible gaps in my understanding. 4. Separate gate resistors are pretty common. In fact almost every hobby level RC ESC has separate gate resistors. Nothing to praise for. The logic board also have pretty basic mistakes in the power stage design and MOSFET driving, but I think my points is enough to not call this controller a good design. I am not a fan of KO controller or any other and you can check my points are valid or not with your engineers. I will appreciate the response.

[@de-bodgery]

I'll respond to this later in full. Just wanted to thank you for responding for now.

[@de-bodgery]

Hi! Long response... 1. Big gaps, lol...seen much wider gaps in most everything else! I consider the gaps between the copper busses and the mosfets acceptably small compared to most everyone else. BV and Frank are getting them way tighter, but not many others are! 2. Thermistor placement is never ideal. In an MCPCB design, heat from any one mosfet bank bleeds over to the others. About best you can do is notice that it's warmer under load at one set of mosfets vs anotehr set. As soon as you reduce load that heat spreads out and they all level out pretty quickly. The hhase buss copper does create a copper mass that can hold heat longer. It's also soldered down to the MCPCB and will let go of heat jsut as fast as that can transfer to the heat sink. It does change temp readings by leveling them out more. However, it's still the best of compromises. Put the thermistor at the high side mosfets and now you don't know what's happening with the low side. So it's either make the compromise made or use 3 more temp sensors! This placement isn't wrong, just the best of the compromises. 3. Vertical cylinders are press fit into flat copper bar. The production unit I have is a very early one. The level of precision was not dialed in yet and so I got one with small gaps. If you look at the white pre-prod power stage I have, this is the expected fitment for production. I showed this to Matt from EBMX and he already knew about the issue and had it corrected so that fitment was much tighter and the 2 parts are plated as a single whole so this gap can't exist and the parts are locked together with metal. 4. I've seen a LOT of controllers with a single shared gate resistor. It is much less than 50% have them individually per gate. I'd say it's note worhty when it's there. 5. If you are part of the VESC Development forum, then you already know a bunch of those engineers I talk to. I'm not going to say names here, but that's a common source I use for things that I don't understand or want confirmation. You may have even seen my sub thread there.