thorlancaster328
100 W
- Joined
- May 25, 2018
- Messages
- 197
With the stimulus checks for COVID and my old bike starting to show its age, I've decided it's time for an upgrade. I'm planning on purchasing a frame from Vector eBikes (Pretty good company AFAIK) and a QSMOTOR v3 rear hub. My current battery is super overkill for what it's doing (2 kWh of Samsung 30Q goodness) and I am itching for an upgrade.
However, my current controller is only good for 60 battery amps. It is a really cheap ($35) Chinese 18-FET controller with quite a few mods. It performs well but I don't want to push it any further or I'm afraid I'll blow it.
Since my last attempt at building a controller (which failed miserably), I've gotten a lot better at power electronics. Last summer I built a 1kW subwoofer amp for my car (runs off an eBike battery) and it's been quite reliable. When laying out the amplifier circuit, I kept loop area down as much as possible to minimize inductance and my cheap o-scope showed a lot less noise. Looking back at my first attempt I can't help but gag. I don't even know how much inductance there was but I wouldn't be surprised if it was 5x what a proper design would be.
To start my new design, I will essentially copy the board layout of a generic 12-FET controller, with either 12 HUGE IRF100P218https://www.digikey.com/en/products/detail/infineon-technologies/IRF100P218XKMA1/8627116s or 24 standard sized IRFB4110s. I'm currently leaning towards the larger TO-247 FETs because they have 4x less internal resistance and I'll only have to fit 12 FETs instead of 24. Only downside is that a set of TO-247 FETs costs about $80. A bit pricey but they should be bulletproof as I use shoot-through proof gate drivers and proper protection circuits (and fuses at first).
For the microcontroller, I plan on using a Teensy 4.0 development board. With around 750 MIPS non-overclocked, I could probably write the firmware in CIRCUIT PYTHON and be fine. (Just kidding I'll do it in C++).
To assemble everything together, I plan on screwing the FETs to an aluminium heat spreader (with kapton) and then bolting that to a hollow aluminium extrusion that will form the main case of the controller. Anyone know a good source for finned hollow extrusions?
However, my current controller is only good for 60 battery amps. It is a really cheap ($35) Chinese 18-FET controller with quite a few mods. It performs well but I don't want to push it any further or I'm afraid I'll blow it.
Since my last attempt at building a controller (which failed miserably), I've gotten a lot better at power electronics. Last summer I built a 1kW subwoofer amp for my car (runs off an eBike battery) and it's been quite reliable. When laying out the amplifier circuit, I kept loop area down as much as possible to minimize inductance and my cheap o-scope showed a lot less noise. Looking back at my first attempt I can't help but gag. I don't even know how much inductance there was but I wouldn't be surprised if it was 5x what a proper design would be.
To start my new design, I will essentially copy the board layout of a generic 12-FET controller, with either 12 HUGE IRF100P218https://www.digikey.com/en/products/detail/infineon-technologies/IRF100P218XKMA1/8627116s or 24 standard sized IRFB4110s. I'm currently leaning towards the larger TO-247 FETs because they have 4x less internal resistance and I'll only have to fit 12 FETs instead of 24. Only downside is that a set of TO-247 FETs costs about $80. A bit pricey but they should be bulletproof as I use shoot-through proof gate drivers and proper protection circuits (and fuses at first).
For the microcontroller, I plan on using a Teensy 4.0 development board. With around 750 MIPS non-overclocked, I could probably write the firmware in CIRCUIT PYTHON and be fine. (Just kidding I'll do it in C++).
To assemble everything together, I plan on screwing the FETs to an aluminium heat spreader (with kapton) and then bolting that to a hollow aluminium extrusion that will form the main case of the controller. Anyone know a good source for finned hollow extrusions?