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Mean Well RST-10000 10kW power supply with 24, 36 or 48 Volt output

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NiHaoMike:
Figure out how the PIC is disabling the PWM and override it. Finding the datasheet for the main PWM controller would be useful there.

BUAROD:
Hello NiHaoMike!
Thank you for your advice!

The PWM controller is a UCC2895DW with pin 19 (SS/DISB) allowing soft-start and disabling: below 0.5V the controller shuts down.
Also pulling pin 4 (REF) below 4V will cause a reset according to the TI data sheet (page 16).
With the conformal coating on the board it is not so easy to find the path to the PIC, but I will manage this ...

However, when overriding the controllers input, I am concerned what happens with the (safety) functions the PIC normally handles?
Are overload, overvoltage, short circuit detection etc. managed by the PWM controller and the PIC is just responsible for even current distribution? 

PS: a few days ago I asked Mean Well Europe for information about switching the RST-5000 in series ... so far no answer! 

 

NiHaoMike:

--- Quote from: BUAROD on October 23, 2021, 01:42:40 pm ---However, when overriding the controllers input, I am concerned what happens with the (safety) functions the PIC normally handles?
Are overload, overvoltage, short circuit detection etc. managed by the PWM controller and the PIC is just responsible for even current distribution? 

--- End quote ---
On a power supply that well designed, it's unlikely they'll be relying on software for protection. You can always add your own protection circuit to it.

BUAROD:
After checking several components I found two defective opto couplers. They enable remote switching of the output.
The input circuitry of the RST-10000 PCB seems to be different to the regular RST-5000 PCB: with identical external
wiring the LEDs inside the opto couplers were damaged. After changing the couplers the power supply works again!

I will now continue my attempt to separate the subassemlies to be able to switch them in series ...

Update Oct. 27th:
I took away the bus bars, connecting the outputs of the subassemblies. The two PICs communicate via the isolated Tx/Rx opto-coupler link (picture 1).
After removing the "interface board" (picture 6) each subassembly has its own wiring now with 2k Ohm in series for the ON/OFF opto-couplers (picture 2 +3).
When switching input power on, both subassemblies switch from red to green LED ... but only the right one (master?, picture 4 + 5) activates the output voltage.
Normally the ouptut voltage level can be set with one potentiometer on the "interface board" (picture 6). For testing I used a 1k Ohm resistor for each subassembly.
Measuring the impedance of the resistor inputs shows different values: so it seems that the left control board (slave) has a different population.
The next step will be to check the differences and change the slave PCB to be same as master PCB.

Update November 1st: 
Topic:  can you change a Mean Well RST-10000 series 10 kw power supply with little effort so that the output voltage is doubled?
The answer is: yes, this is very easy because the 10 kw series consists of two almost identical and interconnected 5 kW modules!
Of course the max. output current is halved: I have done the modification with a 24 V / 400 A version which has a 48 V / 200 A output now!
As tests relating to safety (OVP, excess temperature, current limitation, etc.) are still pending, accept the following listing as preliminary, please!
 
The attached pictures now correspond to the step numbers below:

1. swap the three-wire connection cable between the CN308 connectors on the control boards for an insulated version with optocouplers.
A 5 V supply voltage can be taken from the not used CN309 (picture 1_1 + 1_2).
2. remove the "capacitor - PCB" mounted between the bus bars: in the 24 V version there are 4x 2.200 µF / 35 V assembled, obviously to reduce the ripple voltage
(picture 2). Pay attention to capacitors voltage rating after doubling the output voltage!
3. remove the bus bars, the "interface board" and all its connections to the control boards (pictures 3_1 + 3_2).
4. switch the control board inputs individually, as indicated in the manual. Important note: an additional 2 kOhm resistor must be added in series to the supply line
of the ON / OFF optocoupler, because a 0-Ohm serial resistor is fitted on the control board. Without this external series resistor, the LED inside the optocoupler would
be destroyed when 12 V are connected. The left module is the slave (picture 4_1), the right module is the master (picture 4_2)! To get and ON/OFF indication on the
slave board, 2 LEDs can be soldered directly to the PCB (picture 4_1). On the master board connector pins can be used (picture 4_2).
5. the two control boards (master / slave) differ slightly: a 470 ohm pull-up resistor for setting the output voltage level by a resistor is not fitted on the slave control
board (picture 5_1). Add a 470 Ohm resistor to get same situation as on master PCB (picture 5_2).
To access this position on the slave control board, the complete right module including its EMI - filter PCB must be removed!
Remark: setting the output voltage with a control voltage has not been tested so far. Pay attention to keep the "grounds" separated!
6. connect the positive output of the left module with the negative output of the right module, ideally with a shunt resistor to allow easy current measurement (picture 6).
If the positive sense input of the left module is not connected to its positive output but to the negative output of the right module the voltage drop of the shunt
is automatically compensated!   
8. if ripple voltage is an item, connect additional capacitors to the output(s)!

Any questions?
 


 

BUAROD:
... and finally a picture of max. load testing: 48 Volt with approx. 200 Amp!

Features added to make operation more comfortable and save:
- ON/OFF switch
- contact protection
- voltage adjustment (10 ... 55V)
- current limit adjustment
- voltage and current indicators

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