Is there a way to model the mean well CSP-3000-120 supply on LTspice?

Thread Starter

rfengineer28

Joined Apr 28, 2021
71
Hello i am working on a project that will be using this ac/dc power supply as input and i was wondering if there was any way to model this supply on LTspice.
 

Thread Starter

rfengineer28

Joined Apr 28, 2021
71
You can model it as a voltage source with an internal resistance. Will that work for you?
ive been trying something like that, just doing ohms law and i get a resistance of 4.8 ohms when using a current of 25A and 120V. However, when i measure current at the end of the simulation i then have an average current of 2.5A which doesnt make sense. and then i get a signal thats boderline clipping.
 

BobTPH

Joined Jun 5, 2013
5,506
Post your circuit. 4.8 Ohms would be the load that would take 25A at 120V. That is not the internal resistance.

When you power a load with it, it will supply only the current needed by the load. And the voltage will stay at close to 120 up to 25A. It will probably shut down if you overload it.

What is it that you need to simulate? If you are using it within specs, the voltage should remain constant.

Bob
 

Thread Starter

rfengineer28

Joined Apr 28, 2021
71
Post your circuit. 4.8 Ohms would be the load that would take 25A at 120V. That is not the internal resistance.

When you power a load with it, it will supply only the current needed by the load. And the voltage will stay at close to 120 up to 25A. It will probably shut down if you overload it.

What is it that you need to simulate? If you are using it within specs, the voltage should remain constant.

Bob
thank you, i am trying simulate my h-bridge circuit driving a brushed dc motor that has a max stall current of 64.5A. i am trying to design for worst case scenario. the supply i am using has an output of 120V and 25A, and i am just trying to get as close of a simulation as possible.

1654215504825.png

https://www.meanwell.com/webapp/product/search.aspx?prod=CSP-3000

1654215617395.png
 

BobTPH

Joined Jun 5, 2013
5,506
So you are not using it within specs. Not a good idea.

Putting a 4.8 Ω resistor in series with the power supply guarantees that it won’t output more than 25A, but it is not close to simulation of it. The only way to get 25A out is with a short circuit. If you load really want a 25A, then with the series resistor it will see only 60V.

Looking at the specs, I think this supply is going to shut down if it sees anything like the 65A stall current.
Bob
 

Thread Starter

rfengineer28

Joined Apr 28, 2021
71
So you are not using it within specs. Not a good idea.

Putting a 4.8 Ω resistor in series with the power supply guarantees that it won’t output more than 25A, but it is not close to simulation of it. The only way to get 25A out is with a short circuit. If you load really want a 25A, then with the series resistor it will see only 60V.

Looking at the specs, I think this supply is going to shut down if it sees anything like the 65A stall current.
Bob
now I am worried. perhaps should I begin designing my circuit with IGBT's instead?
 

Thread Starter

rfengineer28

Joined Apr 28, 2021
71
So you are not using it within specs. Not a good idea.

Putting a 4.8 Ω resistor in series with the power supply guarantees that it won’t output more than 25A, but it is not close to simulation of it. The only way to get 25A out is with a short circuit. If you load really want a 25A, then with the series resistor it will see only 60V.

Looking at the specs, I think this supply is going to shut down if it sees anything like the 65A stall current.
Bob
perhaps building a current limiting circuit into the H-bridge do the job?
 

crutschow

Joined Mar 14, 2008
30,460
The supply is regulated to 0.5% which gives a 0.6V max drop at 25A.
Thus a 0.6V / 25A = 24mΩ series voltage supply resistance would simulate that.

The current limit will shut down the supply over 105% of 25A and the supply has to be turned off and back on to reset.
The shutdown delay can be set to 3 seconds, so if the motor is trying to draw more than 25A after that, the supply will shut down.

Below is one way to do a simulated current-limit in LTspice:
1654232370964.png
perhaps should I begin designing my circuit with IGBT's instead?
Don't see how that will help, as you can buy MOSFETs to handle the high current, and IGBTs have a much higher on-voltage drop, and thus higher dissipation,
 

Thread Starter

rfengineer28

Joined Apr 28, 2021
71
The supply is regulated to 0.5% which gives a 0.6V max drop at 25A.
Thus a 0.6V / 25A = 24mΩ series voltage supply resistance would simulate that.

The current limit will shut down the supply over 105% of 25A and the supply has to be turned off and back on to reset.
The shutdown delay can be set to 3 seconds, so if the motor is trying to draw more than 25A after that, the supply will shut down.

Below is one way to do a simulated current-limit in LTspice:
View attachment 268636
Don't see how that will help, as you can buy MOSFETs to handle the high current, and IGBTs have a much higher on-voltage drop, and thus higher dissipation,
Thank you for sharing that with me. so what I am gathering is that the power supply is supposed to shut itself down if it detects a sudden draw <25A for an extended amount of time or if a mosfet goes bad and shorts itself to ground, right? I know the motor is rated for a peak 65A and I don't want to get to that. Now, on another note I was reading one of your responses from 2015 and I saw that you recommended someone to use a current limit circuit in series with the transistors to protect them from overcurrent since a fuse wouldn't protect the semiconductor devices, in my case would I build one for all 4 MOSFETS?
 

BobTPH

Joined Jun 5, 2013
5,506
You probably want an unexpected stall to shut it down, not continuously put 25A into the motor when something has mechanically stopped it from spinning.

The other issue is on start and direction change. I think a soft start is the way to deal with that.

Bob
 

Thread Starter

rfengineer28

Joined Apr 28, 2021
71
You probably want an unexpected stall to shut it down, not continuously put 25A into the motor when something has mechanically stopped it from spinning.

The other issue is on start and direction change. I think a soft start is the way to deal with that.

Bob
I think finding a way to have a soft start will be the way to go to avoid any stall or inrush current from starting up.
 
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