Circuit Modifications for reducing current

[Dipali2014]

Hello everyone,

I am currently working on a BLDC fan project using Renesas MCU RL78/G14 R5F104BA. I have a board which includes driver circuit,ADC LM339 circuit and Controller circuit. This board is designed for 12V BLDC Fan. I want to use the same circuit for 24V fan. I have done some changes in driver circuit resistors and now its working properly for 24V. But wattage is high. The current reading is 24V 320RPM and 1.5A current. I want to decrease the current reading. Please suggest the changes

 

[davenn]

the fan will draw whatever current it needs
if you do something to decrease the current supplied to the fan, this wont be performing optimally

 

[(*steve*)]

if you want to reduce the current reading, simply place a shunt across the current meter. It will then read lower.

 

[Alec_t]

Change the fan for one with an inherently lower current draw. Reducing the fan current by other means will reduce its torque and speed.

 

[AnalogKid]

if you want to reduce the current reading, simply place a shunt across the current meter. It will then read lower.

6 years and 20,000 responses, and that's the best you can come up with? Granted the question was *slightly* poorly worded, but do you really think that was an informative response?

ak

 

[cjdelphi]

I thought it was, the shunt would limit the current to the fan...

(Dump it for a pwm controlled fan)

 

[AnalogKid]

I thought it was, the shunt would limit the current to the fan...

Nope. An external shunt would be in parallel with the meter's internal shunt, and thus would *increase* the current to the fan while making the meter reading completely incorrect. That way lies folly.

ak

 

[Dipali2014]

Thank you guys for reply but can someone suggest proper solution or any changes in circuit?

 

[AnalogKid]

Text on the schematic is very small and very difficult to read, but I don't see any inductors. Where is the rest of the schematic that has the motor coils. power devices, etc? Generally speaking, the way to decrease the power dissipated in something operating with a fixed voltage is to increase the device's impedance at its operating conditions. In your case, assuming that you can't just double the operating frequency, that means winding new motor coils with a higher inductance.

ak