braking resistor for IM drive ( regenerative power)

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nabil2018

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Hello and good day

I am facing big issue in the Induction motor drive system. I am using IM drive system with three phase inverter and three phase 2hp induction motor with Dspace 1104 .I am running the motor at rated speed 1400 rpm with 540vdc coming from rectifier . I am using 4 capacitor as filter circuit. My problem when i reverse the motor speed ,my IGBT always shorten ,I suspect the regenerative power coming from the motor,so i installed 8 resistor with 2.1K 5 watt to absorb the regenerative power,however this effects the drive system in the motoring mode it broke the igbt at 400 vdc .So i dont know what resistor value i should select and what wattage in order to prevent the regenrative power and doest affects the drive in the motoring mode.
please advice me in selecting the right braking resistor for my drive
 
nabil2018 said:
Hello and good day

I am facing big issue in the Induction motor drive system. I am using IM drive system with three phase inverter and three phase 2hp induction motor with Dspace 1104 .I am running the motor at rated speed 1400 rpm with 540vdc coming from rectifier . I am using 4 capacitor as filter circuit. My problem when i reverse the motor speed ,my IGBT always shorten ,I suspect the regenerative power coming from the motor,so i installed 8 resistor with 2.1K 5 watt to absorb the regenerative power,however this effects the drive system in the motoring mode it broke the igbt at 400 vdc .So i dont know what resistor value i should select and what wattage in order to prevent the regenrative power and doest affects the drive in the motoring mode.
please advice me in selecting the right braking resistor for my drive
Click to expand...
So it appears that rather than buy a commercial off-the-shelf VFD from someone experienced in avoiding all of the pitfalls of building them, you decided that you could make your own from a PC and some transistors. Now you want someone else to tell you how to fix the problems you created for yourself....

Sounds as though you have neglected to consider how you would move the regenerated energy from your DC bus into a braking resistor. You need a chopper transistor circuit. I also think your choice in resistors is going to be woefully inadequate. You have (possibly, depending on how you connected them) 40W of braking capacity for a motor capable of creating 1500W of energy.
 
Jraef said:
Sounds as though you have neglected to consider how you would move the regenerated energy from your DC bus into a braking resistor. You need a chopper transistor circuit. I also think your choice in resistors is going to be woefully inadequate. You have (possibly, depending on how you connected them) 40W of braking capacity for a motor capable of creating 1500W of energy.
Click to expand...
Totally agree. Not sure that the OP qualifies to be posting here if he came up with such a basic mismatch in power.
 
Besoeker said:
Totally agree. Not sure that the OP qualifies to be posting here if he came up with such a basic mismatch in power.
Click to expand...

Possibly he is venturing into a new area. We were all noobs once upon a time. As far as VFD's are concerned, I wouldn't care to offer many opinions but I try to learn as much as I can from discussions here. You never know what you might need someday.
 
gadfly56 said:
Possibly he is venturing into a new area. We were all noobs once upon a time. As far as VFD's are concerned, I wouldn't care to offer many opinions but I try to learn as much as I can from discussions here. You never know what you might need someday.
Click to expand...
No disagreement with any of that.
However, the OP seems to be trying to design his own VSD which seems a bit pointless when commercially available products abound. And, at that power rating, as cheap as chips.
Just my idle thoughts.
 
Besoeker said:
No disagreement with any of that.
However, the OP seems to be trying to design his own VSD which seems a bit pointless when commercially available products abound. And, at that power rating, as cheap as chips.
Just my idle thoughts.
Click to expand...

Always willing to learn, I did a little poking around and found a product here that to my untrained eye looks like what the OP needs. It clocks in at US$636. Is this "cheap as chips" in the VFD world?
 
Thought the OP may be designing for an aerospace application, but 'induction motor' kills that thought. Last aerospace vfd induction motor I saw was in 1992, now all are PM.
So, perhaps nabil can share his application that requires a non standard vfd ?

1400 rpm and Malaysia implies 50 Hz source, but may be irrelative.
 
junkhound said:
Thought the OP may be designing for an aerospace application, but 'induction motor' kills that thought. Last aerospace vfd induction motor I saw was in 1992, now all are PM.
So, perhaps nabil can share his application that requires a non standard vfd ?

1400 rpm and Malaysia implies 50 Hz source, but may be irrelative.
Click to expand...

Here is something suggesting that the standard low voltage is 415/240 at 50 Hz.
 
gadfly56 said:
Always willing to learn, I did a little poking around and found a product here that to my untrained eye looks like what the OP needs. It clocks in at US$636. Is this "cheap as chips" in the VFD world?
Click to expand...

That drive you linked to is 575V, particularly hard to make and extra expensive as a result. I seriously doubt he has access to components to built anything more than a 240V version. That's also a highly complex drive, whatever the OP made from scratch is going to be minimally functional, if at all. You can find a 2HP 240V minimalist drive for about $150.00, ready to turn on.
 
1200V devices are good for 240 and 480V, true, bit not 600V class. The voltage rating needs to be 2.5x the AC line voltage to survive. Only 1% of semiconductor devices pass at 1600V (the next test level), making them much more difficult to get and more expensive.

This has gone off topic though. The point I was originally making was that the OP appears to be in over his head and this forum is not about design engineering for the DIY electronics crowd, it's about helping electricians to do their jobs more effectively. Let's not go further with it.
 
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