james81
Newbie level 6
Hi Guys
So I have just built this inverter but I have an issue trying to get it to work..
Firstly all parts appear to be working fine independently, and with H-Bridge disconnected I get a pretty stable 340v DC from the rectifier.
I also get SPWM from the H-Bridge using a 12v supply.
But, when the 340v dc is connected with the H-bridge, the rectifier voltage drops to around 40v dc at the rectifier and I get 18v AC rms at the H-Bridge output.
This tested without load connected and before the LC Filter stage, which I haven't got to yet.
Any ideas why this is happening?
*So far I have destroyed my rectifier -
I was thinking my problem may be because the inductor needs minimum load, for continuous current mode.
And, as I had a current limiting resistor in place between the source and ground of the Half-bridge mosfets, I decided to remove that first.
(This was initially in place to prevent any damage to the circuit as I wasn't sure how the circuit would behave)
I replaced the resistance with a 3 amp fuse as this would be enough to allow CCM on the primary whilst protecting the mosfets in case something goes wrong.
(The mosfets can handle around 16 amps)
School boy error though, should have disconnected the rectifier, blew two of the diodes, and now waiting for new diodes.
In hindsight i'm a bit annoyed at myself as I hastily used a standard BS-1362 plug top fuse, and probably not wise for 12v supply.
I think this might have caused a voltage spike on the primary, exceeding 600v rating of the diode - although if this is the case i'm not sure if I could blame the fuse?
Until I get new diodes I am at a lose end trying to think of reasons why the primary side voltage drops so abruptly when the H-bridge is connected.
If anyone is able to give some guidance, Id appreciated the help.
There is another issue regarding the SG3525, I have the frequency set using the components as shown on the diagram - this does not produce the calculated 188 kHz though, it give me the 100kHz I require, not quite sure why that's happening?
Thanks
James
So I have just built this inverter but I have an issue trying to get it to work..
Firstly all parts appear to be working fine independently, and with H-Bridge disconnected I get a pretty stable 340v DC from the rectifier.
I also get SPWM from the H-Bridge using a 12v supply.
But, when the 340v dc is connected with the H-bridge, the rectifier voltage drops to around 40v dc at the rectifier and I get 18v AC rms at the H-Bridge output.
This tested without load connected and before the LC Filter stage, which I haven't got to yet.
Any ideas why this is happening?
*So far I have destroyed my rectifier -
I was thinking my problem may be because the inductor needs minimum load, for continuous current mode.
And, as I had a current limiting resistor in place between the source and ground of the Half-bridge mosfets, I decided to remove that first.
(This was initially in place to prevent any damage to the circuit as I wasn't sure how the circuit would behave)
I replaced the resistance with a 3 amp fuse as this would be enough to allow CCM on the primary whilst protecting the mosfets in case something goes wrong.
(The mosfets can handle around 16 amps)
School boy error though, should have disconnected the rectifier, blew two of the diodes, and now waiting for new diodes.
In hindsight i'm a bit annoyed at myself as I hastily used a standard BS-1362 plug top fuse, and probably not wise for 12v supply.
I think this might have caused a voltage spike on the primary, exceeding 600v rating of the diode - although if this is the case i'm not sure if I could blame the fuse?
Until I get new diodes I am at a lose end trying to think of reasons why the primary side voltage drops so abruptly when the H-bridge is connected.
If anyone is able to give some guidance, Id appreciated the help.
There is another issue regarding the SG3525, I have the frequency set using the components as shown on the diagram - this does not produce the calculated 188 kHz though, it give me the 100kHz I require, not quite sure why that's happening?
Thanks
James