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Three-phase inverter for Induction motor.

nguyenhuuphuoc

Dec 19, 2018
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Dec 19, 2018
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Hello everyone.
I'm doing a circuit control induction motor 3 phase, using optocoupler and IGBT. Now, circuit was working and motor was run. But the problem I meet is three low-side (UL, VL, WL) always high temperature, but high-side does not.
Anyone who maked this project can help me with this problem? Thank you so much.
 

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Alec_t

Jul 7, 2015
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Welcome to EP!
You haven't shown the complete schematic, so it's impossible to say with any confidence where the fault might lie. As shown, for example, the LED cathodes are unconnected and there are no power supplies, so none of the IGBTs should be active.
 

nguyenhuuphuoc

Dec 19, 2018
2
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Dec 19, 2018
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Thanks so much Alec_t.
All Cathodes is connected to the GND of MCU. Voltage bus I supply about 300V. For the optocuplers in high side (UH, VH, WH) I supply 22V for each optocoupler and all optocoupler in low side (UL, VL, WL) I supply common 22V.
I decrease gate resister, from 150 to 47 ohm. So the temperature of low side significantly decrease, but still higher than high side.
 

Harald Kapp

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Nov 17, 2011
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How is GND of the HCPL_3150 connectd on the high side and the low side?
You really should provide a complete circuit diagram (at least of this part of your circuit) as requested by Alec to allow us closer inspection. With the rudimentary extract you have provided we are more or less helpless.

I decrease gate resister, from 150 to 47 ohm. So the temperature of low side significantly decrease, but still higher than high side.
This sounds like you may have an issue with the timing - turning the MOSFet on and/or off too slowly. Showing us timing waveforms for the gate control voltages (measured, not theoretical) will also help in analyzing your issue.
 
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