# Thread: PFC fault if input voltage < 210Vac

1. ## PFC fault if input voltage < 210Vac

Hello

I will start to evaluate the IMC102T-F064 with the evaluation board IMC102T-F064 and EVAL-M3-CM615PN.

I set the PFC target voltage to 400V.
It is ok, I obtain the 400V with AC input voltage range from 190Vac to 270Vac.

But when I start the motor, during acceleration, the input AC current goes up to 4.8A, but on this current pic, the PFC fail and generate a fault (PFC_FaultFlag = 1) if the input VAc is < 210Vac.

The evaluation board caracteristic indicate 190-265V.

I tested with self of 2.5mH and 4mH (@ 1KHz).

I also tested by seting the Target voltage to 350V without success.
I also tested by increasing PFC Average Inductor Current limit from 5A to 7.4A (Q 119) without success.
We seen primary current rise to about 5A, then after, PFC fault so the DCBus voltage fall.

Is there some tune to do? Or maybe I must increase the self value?

2. Could you please share the screenshot you reference?

3. Hello,

1) Graph with
- Vac = 230V
- PFC Target = 400V
- Motor 1 OVC Trip Level (93) = 5A
- PFC Average inductor Current limit (119) = 5A
- PFC OVC protection (126) = Disable

- CH3 = PFC voltage,
- CH4 = Inductor Current

=> All it is OK

The cycle is Acceleration from 0 to 2400 rpm with 800rpm/s (Acceleration time = 3s)
Then Wait and decelerate (On Deceleration we see the load resistor driven by own script to avoid DCBus OverVoltage during regeneration phase)

2) Graph with
- Vac = 195V
- PFC Target = 400V
- Motor 1 OVC Trip Level (93) = 5A
- PFC Average inductor Current limit (119) = 5A
- PFC OVC protection (126) = Disable

- CH3 = PFC voltage,
- CH4 = Inductor Current

Same but with current sensing on VAC input

We could imagine this is normal because current grow > 5A,

Then I test also by change:
- PFC Average inductor Current limit (119) = 7.4A

=>Same Result,

Then after (by keeping (119) = 7.4A) , change
OVC motor (93) = 10A
=> Same Result,

Then I also vhange PFC OVC (126) = Enable

=> Same Result

All sequence finish always by a PFC Fault (Not Motor Fault), with PFC_FaultFlag = 1.

Edit: I attached oall my files (Files.zip)
Files.zip

4. Hi Arnaud,
Thank you for the screenshots.

Please try the latest MCEWizard v2.3.1 and the latest firmware v1.3.3.

The PFC current limit does not work. Please refer to the updated MCEWizard 2.3.1 where this question should be removed. Also, set the OCP to cycle-by-cycle in the new MCEWizard.

5. Hello

I update firmware/software like you asked.
I change the PFC to "Cycle-by-cycle"

=> then The PFC hold the load during acceleration time, no PFC fault generated.

If I set again to Latch-Off, the problem comes back again.

Ok, I think it is ok because we "desactivate" the hardware protection in case of OVC..
But we need this protection.

In Reference manual, it is indicated the LatchOff option allow to switch off the PWM. It is the behavior we need to protect board agains short circuit.
Some simple calculation are done to determine the OVC threshold into the reference manual => 6.88A.
I can imagine this threshold is reach whenever I don't see on the scope because the PFC will limit the current, but after the "PFC_GateKillTime" the fault is generated

So I think I need adjust R25, R6, R8, R9, Rsh to modify the OVC threshold (Increase up to 7 - 8 A) and or adjust the GateKillTime.

But I can't found the GateKilltime parameter. Which is this parameter?

I think I just need adjust OVC threshold and Time...

6. Hi Arnaud,

Modifying R25, R6, R8, R9, Rsh will modify the pfc current sensing scheme as described in 5.1.3 of the EVAL-M3-CM615PN manual. 5.1.4, Figures 16 & 17, show the circuit that determines the PFC overcurrent trip level.

You are right. The PFC_GateKillTIme is not in MCEWizard. Please adjust this value in MCEDesigner. You can find the register in the PFC window Register Structure Definition -> Write Registers -> Protection.

7. Hello,

Like the IGBT of the PFC (IFCM15P60GD) can support Ii(peak) of 60A less than 1ms, I think I could change the getKill timer tot he max value (960) whcih correspond about 10µs only with a threshold configured by hardware resistor about 6.5A..
But when I try to write the PFC_GateKillTime from MCEDesigner, I get a message:
"Register "PFC_GateKillTime" is static type and cannot be written. If this operation is real needed, USER needs unlock the static register operation. (warning: this operation is dangerous)"

Then I refer to the Reference manual:

2.4.4.2.3 Access Static Parameter
Writing to those static type of parameters is not allowed by default. A 2-step unlock process is needed to obtain
write access to the static type of parameters. Without going through this process, attempting to write to those
static type of parameters would have no effect.
The 1st step is to have the master send a command frame (MO = 1) with Command = 0x0000 and Value = 1 to
unprotect the next 1 command.
The 2nd step is to have the master send a command frame (MO = 1) with Command = 0x0002 and Value = 1 to
Then the master has the right to write to those static type of parameters using a command frame with MO = 7.
After the write operation is completed, it is recommended to disable the write access to those static type of
parameters by the same 2-step lock process.
The 1st step is to have the master send a command frame (MO = 1) with Command = 0x0000 and Value = 1 to
unprotect the next 1 command.
The 2nd step is to have the master send a command frame (MO = 1) with Command = 0x0002 and Value = 0 to
So this operation could be done via the UART1. But currently on the Evaluation board, I havent access to this UART1 (I must realize an isolator adaptation etc...)
Is there a way to modify PFV_GateKillTime from MCEDesigner?