HACKED!: Adding a Current Limit Feature to a Buck/Boost Converter
Why Electrical Engineering Stack Exchange recommends it
Electronics Stack Exchange users link it when asking how to add a current limit to a buck or boost converter, since it walks through a simple shunt, op amp and comparator approach.
Recommended by 2 people across 2 different months, 2019 to 2022.
What it is
GreatScott! shows how he modifies a cheap off-the-shelf buck/boost converter module to add an adjustable current limit. He uses a low-value shunt resistor, an op amp and a comparator to cut back the output when the set current is reached, then tests the result on the bench.
What people said
Recommends curious_techie · 2019-12 · Electrical Engineering Stack Exchange · on “Limiting output current of a Buck Converter”
I think I might not have explained the question properly, or you missed out the detail. I do no want to make a constant current source. I want to limit my current at a certain value. I want to achieve this thing ( [this video] ) for my own buck converter
Recommends Bjm · 2022-04 · Electrical Engineering Stack Exchange · on “Help understanding use of step-up boost converter”
This GreatScott video [this video] helped me a lot. I used the same small voltmeter to monitor the voltage/current under load, and as suggested by @Lorenzo, the BPS was too weak. After getting a better PSU, and also limiting the current, it is working.
Cites Trex · 2019-02 · Electrical Engineering Stack Exchange · on “Adding Current limit for DIY DC-DC converter (CC/CV battery charging)”
I was following the circuitry by great Scott for the DIY buck converter here: [LINK] . Created a converter that gives 0-23V on 24V supply. After this i wanted to add different current limits to this buck converter such as 1/2/3/4/5 Amps for charging different li-ion battery pack. For that i am going to follow this" Traditional method of implementing CC/CV "here: [LINK] also have seen this video on adding a current limit to a buck boost converter: [this video] with the shunt resistor and all. Thing is I cannot even understand how is the Traditional method of implementing CC/CV working here and how to approach this software wise. A more in depth explanation could be quite helpful and any type of su
Cites Russell McMahon · 2019-12 · Electrical Engineering Stack Exchange · on “Limiting output current of a Buck Converter”
Links to ESC and motor? Note that you cannot limit the current and voltage if the load would draw more than the desired current at the specified voltage. eg At 15V, 10A - load = V/I = 15V/10A = 1.5 ohms effective. If you load it with 1 ohm and limit current to 10A then Vmax = IR = 10A x 1 Ohm = 10 Volt. The output current and power of the converter is dependant mainly on the MOSFETs used, on their heatsinking and on the main inductor. The MOSFETS datasheet here [LINK] SHOULD be capable of far far far more than 10A continuous if properly driven and properly heatsunk providing the datasheet and parts are genuine. Any inductor failure is most likely to be due to saturation. Saturation can be te
Cites curious_techie · 2019-12 · Electrical Engineering Stack Exchange · on “Limiting output current of a Buck Converter”
I am trying to power a 4S-ESC to drive a BLDC motor using a buck converter and 24V,10A SMPS. However, my buck converter can only handle 10 Amps of current (safely) at 15V through its output side. Therefore, I need to make sure that the output current should not go over 10A, even if I increase the throttle input to ESC. Also, I do not want to put a relay triggered by a current sensor, since that will shutdown the power supply to my motor, which is undesirable. Thus, I want to 'limit' (or 'saturate') the current at 10A. Is there a way to achieve this without hacking the buck converter? If there isn't, these are the details of my buck converter- Description : Non-isolated adjustable synchronous
Cites mairas · 2021-03 · Electrical Engineering Stack Exchange · on “Op amp differential amplifier output level too high”
I'm trying to implement a current limiter for a buck converter charging a 2.7 V super capacitor. The design uses an op amp differential circuit that then feeds a comparator: [LINK] I have simulated the approach, implemented the current limiting circuit on strip board, and also tested the circuit in isolation on the prototype PCB. It works perfectly on all of them: the differential stage output is 50 times the shunt current, and the comparator goes high when the diff. amp output reaches 1.25 V, or at roughly 2.5 A. It's not a precision circuit, so I'm not worried about minor differences, as long as I don't overload the supply. However, when I try to apply the current limiter to the buck conve
Cites mairas · 2021-03 · Electrical Engineering Stack Exchange · on “Op amp differential amplifier output level too high”
FWIW, I took the comparator approach from this YouTube video [this video] . But still, I don't understand why it would have anything to do with the problem of the differential amplifier indicating a current of 2.5 A when there's none. Or that the differential amplifier DC level doesn't follow the shunt DC current.