eldenh
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eldenh's dc-dc Converter Initial Discussions

Thu Oct 22, 2020 9:48 am

Is it possible that the Leaf OBC uses the same control board for the dc-dc converter?
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kiev
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Thu Oct 22, 2020 2:00 pm

The Laef OBC uses many of the same circuits and components on a different board layout, and the same waffle plate. But i don't know about the Laef DC/DC converter, it is housed in a separate box.

One fellow on here had a broken wire in the E-03 connector that carries the 12V and CAN signals to the OBC, he swapped out the OBC but still had a fault with no charging, so that is worth a detailed look especially since it has a really sharp bend in the harness.

i assume you went thru the troubleshooting guide and found nothing a fault in the relays, fuses, connectors, wiring, etc. Not sure how to rule out the EV-ECU but it controls HV charging also and the system cooling is needed for HV charging.

P0A09 Probable Causes:
Damaged wiring harness or connector(s)
Malfunction of system cooling
Malfunction of the DC-DC converter
Malfunction of the EV-ECU
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kiev
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DC-DC Converter internal connector pinout

Thu Oct 22, 2020 8:44 pm

The wires coming into the E-03 connector run thru a watertight feedthru and pass to the CN101 connector on the top board of the OBC, and down thru an opening to the CN201 connector on the DCDC board in the bottom plenum.

There are 2 wires common to both, namely the +12V Hot all the time and ground, which is made by a splice under the heatshrink in the harness to the DCDC.

The DCDC only has 5 wires to CN201:
Pin color function
1 White DCSW
2 nc
3 Red +12V hot all the time thru fuse #11
4 nc

5 Black Ground
6 Yellow +12V switched thru relay A-08X and fuse #7
7 Brown SDW
8 nc

There is no CAN buss lines running to the DCDC; so it could be operated/tested by supplying the necessary discrete signals, namely the DCSW and the SDW, along with the 12V supplies and ground, and a HV source.

The EV-ECU uses relay A-06X to supply the switched 12V thru fuse #11 to the OBC.

Before tracing this out i had assumed that both the OBC and DCDC used the same switched 12V and came ON at the same time, but they are separately controlled and powered.

i suspect the contact points of relay A-08X might be damaged from trying to operate the converter with a weak aux.
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eldenh
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Location: Port Angeles, WA

Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Oct 23, 2020 11:30 am

It looks to me that if relay X-08 had problems several functions couldn't work, but the usual sounds occur when the Ready light comes on and the lights for AC and heater fan operate.
I am having trouble relating the drawings to the wires on my car. I can probe the harness end of the E-03 connector rather easily, but find it very difficult to do so on the OBC end. With key off: pins 1 & 7 have 2 vdc, pin 2 has 4vdc, and pin 8 has 12 vdc. With Ready: pin 1 is 2.24, pin 7 2.75, pin 2 4, and pins 3,, 8, 12, 13 have 12 v. Those pin numbers don't agree with the drawings I've seen.
It seems to me that the problem is in the dc-dc converter and not elsewhere, with the possible exception of the EV-ECU.
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kiev
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Re: Troubleshooting and repair for On-board Charger (OBC), DC-DC Converter

Fri Oct 23, 2020 2:03 pm

The pin numbering stamped on the connectors is not used by Mitsubishi--they have made up their own numbering system. So you have to use the FSM wiring diagrams and the connector pin numbering on those sheets. The view is looking in to the connector and they have a different marking for male and female connectors.

Then to really mess with things, they change the wire color on either side of the E-03 connector.

i will review your notes and get back

Here is my drawing from post #3 of this thread edited to add the CN201 connector
Image
Last edited by kiev on Sat Oct 24, 2020 11:37 am, edited 1 time in total.
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kiev
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DC-DC Converter

Fri Oct 23, 2020 2:44 pm

This is a fairly simple buck converter. The HV comes in from the upper plenum on pink(HV+ or P) and blue(HV- or N) wires. there is a fuse on the (-) side before going thru an EMI filter, Cap-Coil-Cap. The (+) side goes to the Drain of Q103 and Q104, 2SK3697 N-Mosfets, the (-) side goes to the Source of Q101 and Q102. So these 4 FETs make an H-bridge where the Source-Drain connections at the midpoint of the upper-lower legs go to the ends of the primary of Transformer, labelled as TR103-1 and -2. The UC2825A PWM controller chip, IC201, generates the drive signals for the FET Gates. A couple of isolation transformers are used to create the gate drive voltage from the LV 12V supply.

The secondary has a center tap connected to chassis ground. The ends are rectified by a dual Schottky Barrier Diode Module made by Nihon, P2H80QH20, rated 80Amps and 200Vrms. There is a temperature sensor near the diode and voltage sense lines on the input and output of the diode module. The two outputs are connected together and routed thru a thick inductor which uses flat "wire" with 8 x 2mm cross-section. This is the "12V" output and runs thru a current sensor and then a 125A fuse and then on to the fat white wire that runs up to the fusible link on the Aux battery positive terminal.

There is no microcontroller on the DCDC board (at least on the top side, i didn't remove it to inspect the bottom), so as i mentioned earlier i think it could be commanded by the two discretes, DCSW and SDW. Don't know what they are...?
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JoeS
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eldenh's dc-dc Converter Initial Discussions

Wed Oct 28, 2020 10:00 am

This thread was created specifically to capture the initial dc-dc converter discussions which have been subsequently explored in depth in the Gen1 DCDC Converter Troubleshooting and Repair thread.

The reason for doing this is to enable kiev's post to be first chronologically in that thread so he can update it as our knowledge base grows.
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