Rectifier circuit not working.

Thread Starter

haleema05

Joined Jul 8, 2021
11
hi everyone, i need to make a rectifier circuit using mosfets to minimize the voltage drop. i tried making one but it is not working as a recifier and i am unable to understand what i did wrong.
 

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LowQCab

Joined Nov 6, 2012
1,308
You have to have Active-Switching for the FETs,
they will not run themselves.

What is the Voltage and Current that You are wanting to Rectify ?
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Thread Starter

haleema05

Joined Jul 8, 2021
11
i want to rectifie voltage we get from a piezo transducer. Here i made an equivalent circuit of a piezo electric transducer by taking the amplitude and frequency of current source 50 and 200 respectively. i dont know much about electronics, can you please elaborate your statement a little more?
 

LowQCab

Joined Nov 6, 2012
1,308
You don't need a Bridge-Rectifier,
You need an Op-Amp to amplify the Output-Level.

Do You need an AC-Voltage ?, or does your project require DC ?
It would help a great deal if You would simply state what the purpose of Your project is.
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Thread Starter

haleema05

Joined Jul 8, 2021
11
Yep sure. Basically the purpose of making this project is to reduce voltage drop during rectification process by an ordinary bridge rectifier. As piezo transducer dont generate much voltage already and after rectification we got very low output voltage. I want to reduce that voltage drop during rectification, but the circuit is not working as a rectifier at all.
 

AlbertHall

Joined Jun 4, 2014
11,594
Once the diodes have charged up the MOSFET gates, there is no discharge path.
Does the transducer produce enough voltage to turn on the MOSFETs?
 

DickCappels

Joined Aug 21, 2008
7,955
Here is something you might be interested in:
https://www.ti.com/product/BQ25570

In my limited experience using MOSFETs as switches in a diode bridge requires either an inductor or resistor ahead of the peak storage capacitor. That prevents the MOSFET from partially discharging the capacitor after the peak voltage has come and gone. Another approach would be to detect when the peak occurs and switch off the MOSFETs until the next half cycle.

The problem is that, unlike a diode, the MOSFET can conduct regardless of the polarity.
 

Thread Starter

haleema05

Joined Jul 8, 2021
11
i read it and tried to make the circuit accordingly but as i said earlier i have almost zero knowledge about electronics and if anyone of u can guide me in more easy words, that would be highly appreciated, i am really in need of help.
 

AlbertHall

Joined Jun 4, 2014
11,594
See figure 4 of the linked document. Their design includes two synchronous bootstrap pulse generators and a bias-flip circuit with its inductor which you do not have. Also note the substrate connection for N2 and N4 in your post #15. I am not sure where they are connected but not to the source which is the case with discrete MOSFETs.
 
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