Buck Mode Charger

[vihsep]

Hi Johannes,
a couple of questions of the input SIG_Start (pin 7):
- is it a button type input in the inverter mode?
- if so, is it any harm to use a continuous HIGH State?
- is it an unused input in the Buck Mode Charger?

In the picture below is a principle of the Buck Mode Connection.
Which one is the correct position for the current sensor of the phase 1, 1 or 2?

[vihsep]

I started to test my Buck Mode Charger. Driving modes run as they should but the charger mode has some troubles.

Below you can find pics of my Buck Connections, parameters and spot values.

The Battery voltage is 38 V and the charging bus voltage is 50 V.
Relay DC1 powers up the inverter.
Both the FWD and the REV goes HIGH as seen in the spot values.
But however the opmode is off?
After a small delay the PRECHARGE is connected and the charging voltage appears on the voltage bus of the inverter.
Obviously the DCSW doesn't work because of the off value of the opmode.

What makes the opmode to stay as the off value?

[johu]

In buck mode dcsw is governed by udcswbuck. You set it to 40V but your screenshot only shows 38V. Do your 50V make it to the bus?

[vihsep]

Yes, L1 is 50 Vdc and it's in the bus via precharge relay.

[vihsep]

My misunderstanding! I measured the value udc over the battery not over the dc bus of the inverter.
Now the Buck mode started up. There is still something strange about measuring current.

I would like to return to the original post:
- position for the current sensor?
- behavior of the start input?

[johu]

Well you connect the battery to the first or third phase output and that phase must be sensed.
Start input is not needed, software switches to charge mode as soon as it sees forward=reverse=high

[vihsep]

I want to be sure, do you mean that I sense the current of phase of the motor?
But not the sum of the motor and the battery connection currents?

[johu]

Ah I wasn't 100% accurate. So phase 2 is used as source for buck charging, so phase 2 must be sensed. Current then travels through phase 2 IGBT/diode and through attached motor phase.

[vihsep]

O'right I'll try in practice tomorrow.
Thank you so far.