Hi..
We are building the reference design TIDA-00915. If we supply that board with AC input will we get DC output? Apart from the issue of power factory correction should we expect or be wary of any other issue?
Regards
Sam
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Hi..
We are building the reference design TIDA-00915. If we supply that board with AC input will we get DC output? Apart from the issue of power factory correction should we expect or be wary of any other issue?
Regards
Sam
Dear Sam,
the TIDA-00915 board is a DC/AC inverter and requires DC-input voltage of typically 320VDC. The DC input voltage range is 200V to 450V, please see TIDA-00915 design guide table 2, I've copied the specification below.
If you have an AC source, I assume a 230V AC single phase, you will need a bridge rectifier and DC-link capacitors to create a DC voltage with minimum DC-voltage ripple.
Regards, Martin
Dear Martin
Thank you for your response.
We understand that TIDA-00915 is an inverter.
We intend to supply it with three-phase AC to get DC output. We have a reason to do that. Theoretically that should work as that happens all the time when the inverter controls a motor and the motor breaks......we just thought we would ask if there is something that would not allow us to do that in an explicit manner. There might be something in the design that would not permit us to do what we want.
Regards
Sam
Dear Martin
In relation to our question above; we intend to feed the inverter from its 3-phase AC side and hence we will use it as a rectifier. We have a reason to do that.
Based on the rating of the design 00915 (200V, 8Amp) the maximum AC voltage we can feed must have a peak that does not exceed 110V (peak). Correct?
Without any filtering at the DC side this will directly (without any control) get a fluctuating DC voltage of ~ 190V at the DC side. That is, +/- 95V DC , which is 110V * cos (30)). Correct?
We do not have to use FWD ...with your LMG3410......correct?
I am asking that last question because usually in circuit drawings of power switches they draw the anti-parallel FWD, while in the circuit drawings of the LMG that FWD is never there.
Regards
Sam
Hi Sam,
Based on the Table 2 in the Design Guide of TIDA-00915, 3-phase voltage of up to 220VAC RMS can be provided as input if you are using as rectifier.
As for the FWD, LMG3410 can operate in third quadrant with 0V gate drive signal and hence does not need an external FWD. However, VSD drop can be as high as 5-7.8V depending on drain current when gate drive voltage is 0V in third quadrant operation(please refer Section 6.5 of LMG3410 datasheet) - so the dead time should be minimal to reduce third quadrant losses.
Regards
Siva
Hi Sam,
I meant 220V AC rms phase to phase. 380VAC rms phase to phase will give a DC voltage of 537V which is higher than the maximum DC link voltage in Table 2 of design guide. DC link voltage should not exceed 450V and 3-phase AC input should be within a value that does not produce a DC voltage greater than 450V.
Regards
Siva
Dear Siva & Martin,
In using LMG3410-R070 can we use Anti-Parallel Diode (FWD) to reduce losses in the 3rd quadrant? If this is correct do you have recommendation or part number for this FWD that we ideally should use with that LMG.
Regards
Sam
Hi Sam,
Yes, you are correct. 220VAC RMS phase to phase will give ~310VDC.
Thanks
Siva