frenchie Posted January 7, 2017 Share Posted January 7, 2017 Hi all! I have search a lot around this forum and other pages but still haven't found enough detail about the controller card of the Gotway EUC's. In particular the Msuper 3 since I'm currently working on a separate power-board with either 6 sturdier MOSFET's or 12 smaller as the original. Since most controller cards share the same basic setup I suspect that we could gather "all knowledge" in the same thread. One reason to go for 12 MOSFET's is the fact that there are components that them self may cope with currents above 360A but the connector leads stop at around 160-180A. So the first data I'm asking the forum for is Q1: Has anyone done actual measurements on the currents fed thru the motor of a Msuper 3? Preferably also an oscilloscope image... I have read a lot of documentation and can really recommend the Application Note AN-941 from where I quote the summary It is advisable to follow these general guidelines should be followed when paralleling MOSFETs: Use individual gate resistors to eliminate the risk of parasitic oscillation. Ensure that paralleled devices have a tight thermal coupling. Equalize common source inductance and reduce it to a value that does not greatly impact the total switching losses at the frequency of operation. Reduce stray inductance to values that give acceptable overshoots at the maximum operating current. Ensure the gate of the MOSFET is looking into a stiff (voltage) source with as little impedance as practical. Zener diodes in gate drive circuits may cause oscillations. When needed, they should be placed on the driver side of the gate decoupling resistor(s). Capacitors in gate drive circuits slow down switching, thereby increasing the switching unbalance between devices and may cause oscillations. Stray components are minimized by a tight layout and equalized by symmetrical position of components and routing of connections. I myself have not seen the 6 MOSFET-version of Gotways circuit boards but as I have understood the "fix" is to only solder another set on top, there's no other change of components, the impedance from the driver has been left unchanged. Also, as most of you have seen, there's no individual gate resistor, only a true parallel connection with the extra MOSFET simply mounted in the same PCB-hole. This may not be so serious depending on what frequency the PWM is operating at. Which leads med over to the next question Q2: Has anyone measured the PWM frequency of the Gotway controller board? But in general I sort of have a feeling that Gotway had a larger stock of controller cards and the add-on MOSFET is a quick fix. This is one reason they are somewhat reluctant to give hardware support and spare parts, many small re-sellers have tried and failed. It's more a question of selling new EUC's than fixing the ones that break. The plan now is, as I said initially, to build a separate power board. I de-soldered all MOSFET's along with the two 1200μF capacitors. Also all three motor-wires but realised that two of them are measured for current (the ACS709 circuit). Since there's no problem in that area at all I'll feed the current to "MotoA" and "MotoC" back to the controller PCB, keep it simple. Also, the main battery connector will be moved to the Power board, all the high currents will stay there. I will use only small signal wire connection to drive the controller card. The Power board will be mounted on the heat sink and a bigger heat sink will help balancing the heat in between the MOSFET's. Won't fit that big tunnel-thingy with a fan attached but some fan with thermostat will be used. One major drawback is that the electronics is cooled down partly by "air-speed" i.e. going slow on a hot day puts cooling to a test. The stripped controller PCB will fit nicely under the siren, it needs no additional cooling of any sort. If I get no response on the question above, I'll do some measurements o my own, just being lazy here ;0) But, please help out and collect as much electronic data as possible in this thread! Or link to other threads, I'll try to compile all data here if it seems to be spread out... Link to comment Share on other sites More sharing options...
This topic is now archived and is closed to further replies.