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Forum Index : Electronics : Inverter building using Wiseguys Power board and the Nano drive board
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KeepIS Guru  Joined: 13/10/2014 Location: AustraliaPosts: 2261 |
Very Nice captures and information. The cycling hum, which to varying degrees has been there on and off all along, usually at idle, is quite interesting. I say that because I have found changing the layout of the test inverter changes it, sometimes quite dramatically. Various methods to remove residual Toriod Remanence made no difference. I feel that it's some switching component getting back into the a part of the controller and creating a slight mixing or beating condition. A dramatic change happened when I decided to power the Controller from a separate Power source, interested if you find that, both PSUs of course still sharing a common NEG connection. In the Controller running from 15V and the Power board from a 20A 53V supply, the hum stopped, and in the initial setup I had suddenly found I had a cycling hum that was causing a 1000w resistive load to cycle the test Inverter DC input current between 15A and 21A, with separated supplies, that completely disappeared. I've spent time with every type of filtering in the supply to the Controller, nothing worked like a separate supply, different controller versions, different power board builds, ferrite beads, no beads, and always the same dual 23uH chokes, wiring and test Toroid. The above is a very simplified version of the crazy amount of time and testing that I have spent at the Test bench over the years, the Test setup is obviously a worst case layout, and not indicative of a correctly build Inverter, none the less, it can be extremely useful when used correctly. The earlier Single Inverter and the Main Dual Inverter do not do this. The Dual has very neat wiring looms, the input DC to the controller takes a very different route with separated cabling well away from all other cable looms. No power board DC cabling anywhere near the controller and interface wiring, a very large distance between the Toroids, chokes and other wiring and components, a separate ground shield carrier for the Nano controller, a specific cable route for the Controller SPWM cables driving the Power boards, I used a DSO to eliminate a (very) slight disturbance on the switching waveforms which changed with the SPWM drive cable layout, I believe they were coupling some radiated or induced normal power board or DC cabling switching noise back to the controller. It was not causing any hum, just an slight increase in switching fuzz, I'm sure you know what I mean. Do you have to go to these lengths with a typical build, not really, but with the Power and Currents involved in my build, I decided to take my time designing and building this final Dual inverter cabinet and layout. I was determined to make it the simplest Inverter to repair or modify, with ample room in the enclosure for easy access to everything, service access time measured in seconds, including complete unhindered access to the Toroids and chokes if that was ever needed. : Edited 2026-09-11 11:22 by KeepIS NANO:Inverter V 8.4ks - Linux AvrDude GUI script V4.1 |
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| nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 490 |
Thanks for the response and advice about the wiring, there is room for improvement here. My hum is not that loud, when pulling about 3.6A DC, I only see 30mA variance during the event, when pulling 1000W I would not be able to measure a difference during the event, so it is realy not that bad. Going from 4x 8200uF to 8x 8200uF made it a bit lower I think. I think because it is difficult to actualy see improvement or such. Shielding the bottom of the pcb with another pcb thin copper plane did not made a difference. I'm allready using an external isolated dcdc psu with grounds tied together, but not everything in one point. Placed some ferrite clamps on the incomming wires to the pcb. So I think there are no stability issues and I'm chasing a ghost here.  What's on the list to do, will be replacing the thin copper plate by thicker aluminium, make a gnd starpoint and try other powerboards. Edit: another bridge with irfp4110 mosfets gave the same buz. BTW, Wich firmware "core" of Poida are you using? It might have to do something with the moment (after 1 period or 1/2 period) the pwm is altered and the way my scoop is capturing the signals. The hum is just the mechanical effect and a logical consequence. Here is another scope image during the hum, only happening once/period. When there is no hum, current and voltage are on top of eachother. Pink: output ac voltage, yellow: bus voltage, green: bridge current  Edited 2026-09-11 20:20 by nickskethisniks Footnote added 2026-09-11 22:58 by nickskethisniks Guess what, I was able to make the buz worse with an rc of 2n2 and 10 between ac out on the bridge. So it's probably real and noise related. Adding a 0R1 series resistor between bridge and inductor removed the buz but it's not usable. |
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