question

basreflex avatar image

brake for hydropower

markus,

the heater has a very non linear curve, such that It draws quite some current when cold. best solution would be to use a triac driven on input voltage > tbd and use thta the connect to the heater on the AC side of the generator. unless the generator is a 3 phase type, but switching dc powers creates always turn-off surges and sparks. best would be a PWMpower fet control with the heater as a load, so there is no hysteresis and oscillation. allways add surge protectors, snubbers etc.

good luck !

Hydro and Wind Power
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4 Answers
markus avatar image
markus answered ·

Hi basreflex,

thank you. I know that the heater is not an optimal solution in this case. But it works and the voltage stays safely below 250V. Some PWM controlled brake load would for sure be a much better solution. I am far not at the end in optimizations and improvements, and I am very thankful to helpful input. Like yours.

I will keep the community up to date with further improvements.

Regards,

Markus

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basreflex avatar image
basreflex answered ·

if you are confortable with electronics, you could use a silego programmable hardware e.g SLG46620 to control the PWM based on input voltage. I did a battery room fan control triggered at 56V battery and PWM to reduce fan speed at 56V using 2x 24V fans.

happy to share the design

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Hi, thank you. Does this design deal with voltages above 250V DC? But it would be cool, if you share your circuit anyway. Thanks,

Markus


basreflex avatar image
basreflex answered ·

the design runs off the 48V battery so 40-65V range. it uses 4 24 V fans, 2 in series extracting, 2 in series fanCTRL4.pdfpulling fresh air in. the PCB fits in a35mm wide DIN rail housing.

fanCTRL4brd.pdf


the silego files can be made to your likings, like a adding a timer to run the fans longer.


a similar design can be made for 250V , but you need a 250V >5v down converter for the supply, and a 600V fet with snubbers and fet driver for the LOAD resistor. the 250V -> 5V supply could be a universal usb charger for a few bucks. then only the silego and powerfet is needed and a voltage sensing divider. great universal stuff, silego, no C programming needed.


fanctrl4.pdf (31.1 KiB)
fanctrl4brd.pdf (64.2 KiB)
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joe81 avatar image
joe81 answered ·

Hi @Markus, I read your story about the hydropower you used and I have a question: could that heater be used for hot water and heating? I intend to build a vacation home in a remote area and your project is very close to what I have in mind. Maybe if I would get an electric boiler and use the heating element as a load for the water turbine, that way I would solve the hot water problem also. What do you think?

Kind regards,

Joe

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Hi @Joe81,

Yes, it could work to use water heater elements as a dump load.

When you use the dump load to brake your turbine to a safe input Voltage, you have to build it up in a way, so that an opening thermostat can not unload the turbine.

I could think of maintaining temperature in the hot water boiler by adding cold water when the temperature goes too high...

Best Regards,

Markus