Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

3-phase rectifier efficiency

Status
Not open for further replies.
E

esmaeil6514

Newbie level 2
Joined
Jul 30, 2017
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
27
Here is the Description of the issue: We have a 3-phase generator that in its standard working conditions, turning speed is around 3000 to 8500 rpm (which means that the output frequency is around 50 Hz to about 140 Hz). The manufacturer states that the output voltage (phase to phase) is between 35 and 95 V AC depending on speed and 300 W output power is guaranteed even in 3000 rpm without decreasing in voltage level. I want to build a regulator for this generator that be able to give me 30 V DC - 10 A (300 W). The simple solution is using a 3-phase rectifier and a buck regulator. But this solution is two main drawbacks:

The first is for 10 A I would have a 10 A * 1.4 V = 14 W loss just in rectifying circuit and for 90% efficiency I can have total of 30 W in losses. So 14 W its just a lot.
The second is in the case of 95 V AC I would have almost 127 V DC after rectifing! And no ready to use ICs like LM2596 and common buck controllers can handle such voltages.
My primary solution is using 6 MOSFETs (instead of a 3-phase-diode-bridge) like inverters used to control speed of induction motors. And get 30 V DC right after them.
 

Is it a PM excited generator? Otherwise you can control it by varying the excitation current.
My primary solution is using 6 MOSFETs (instead of a 3-phase-diode-bridge) like inverters used to control speed of induction motors. And get 30 V DC right after them.
Click to expand...
How? The circuit does step-up rather than step-down.

There's a number of higher voltage buck controllers like LTC3895.
 

esmaeil6514 said:
Here is the Description of the issue: We have a 3-phase generator that in its standard working conditions, turning speed is around 3000 to 8500 rpm (which means that the output frequency is around 50 Hz to about 140 Hz). The manufacturer states that the output voltage (phase to phase) is between 35 and 95 V AC depending on speed and 300 W output power is guaranteed even in 3000 rpm without decreasing in voltage level. I want to build a regulator for this generator that be able to give me 30 V DC - 10 A (300 W). The simple solution is using a 3-phase rectifier and a buck regulator. But this solution is two main drawbacks:

The first is for 10 A I would have a 10 A * 1.4 V = 14 W loss just in rectifying circuit and for 90% efficiency I can have total of 30 W in losses. So 14 W its just a lot.
The second is in the case of 95 V AC I would have almost 127 V DC after rectifing! And no ready to use ICs like LM2596 and common buck controllers can handle such voltages.
My primary solution is using 6 MOSFETs (instead of a 3-phase-diode-bridge) like inverters used to control speed of induction motors. And get 30 V DC right after them.
Click to expand...
But the problem is "ready to made controllers" like LTC3722 have just a lot of functions and protections that i should use dosens of circuits to manually create them. such a big work! and Of course the Propability to failure in such circuits would be much more than Single-Chip-Solutions like "LM2596".So if you know any IC(buck regulators...Buck controllers... 3phase bridge controllers and...)or have any discreet circuit solution in mind, I'll be grateful if share it with me here.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top