Electrolytic capacitors dont have enough ripple rating for load and power level

[Vbase]

Vbase, sorry but you also dont seem to acknowledge that the Motor cycles to at least 50% more than the average rate. every 1/ cycle per second.
The existing concept is doomed to fail under worst case load.

If I were to offer you a 24V 5A solution now CE rated for above price, would you buy? Not that I'm selling , just asking.

The output dip due to overload is OK for treez.

What cap your solution has after the bridge?

 

[FvM]

To decide if a non-PFC power supply is feasible for the application (e.g. related to power quality regulations), we need to know the load waveform, particularly the Irms and Iavg numbers. Statements about peak current duration vary from 100 ms (in your previous pump thread) and a "some ms" (post #1), makes a big difference regarding IEC 1000-3-2 input power calculation and capacitor ripple current rating.

 

[treez]

The PFC buck sounds good but is unfortunately not isolated.

The existing concept is doomed to fail under worst case load.

Worst case load would have a high peak current, if it was very high then our smps would drop out, and as it dropped out, the ss cap charges up to 5v, and when it gets to 5v it latches off...but we oversize the ss cap so that it doesnt shut down from this kind of overload....in fact, what the worst case overload would just reduce the flow rate.

Sorry to be graphic, but faecal matter, toilet paper etc (that's literally what this pump pumps) gets softer and softer as its left to lie in water, and when softened , is easier to pump, so the ON/OFF/ON... thing takes on a new meaning of benefit.

 

[Vbase]

The PFC buck sounds good but is unfortunately not isolated.

Sorry to be graphic, but faecal matter, toilet paper etc (that's literally what this pump pumps) gets softer and softer as its left to lie in water, and when softened , is easier to pump, so the ON/OFF/ON... thing takes on a new meaning of benefit.

Based on that you can offer cheaper version for vegetarians.

 

[D.A.(Tony)Stewart]

The PFC buck sounds good but is unfortunately not isolated.

Worst case load would have a high peak current, if it was very high then our smps would drop out, and as it dropped out, the ss cap charges up to 5v, and when it gets to 5v it latches off...but we oversize the ss cap so that it doesnt shut down from this kind of overload....in fact, what the worst case overload would just reduce the flow rate.

Sorry to be graphic, but faecal matter, toilet paper etc (that's literally what this pump pumps) gets softer and softer as its left to lie in water, and when softened , is easier to pump, so the ON/OFF/ON... thing takes on a new meaning of benefit.

If fuse rating is 2.5 A and motor cycles between 3.5A and 0.5A or something averaging 2, the fuse wont blow but your cap needs to supply the difference for about 1/3 sec. If your voltage drops then you fail and the product will run slower than the competition. i would then reject the product.

The cap size needed for 1.5A excess in 1/3 sec in a 2 Hz cycle under load and must not dip more than 10% to provide acceptable torque, so the RC time constant must be 6x to get RC=T@60% drop.

Thus if equivalent R is 24V/1.5A=16Ohm
And RC=6x 1/3 sec = 2 sec
Increase in C=2/16= 125,000 uF


Capiche?

do your homework.. Pfc bucks can be isolated and $15 5A 24V SMPS from 120 or 240V are off the shelf !!

I remember being a young green engineer such as yourself and having the same challenge to grasp what my mentor was helping me with, so I understand and he was far less patient.

Btw, To make the product work better you need 28V which it expects from marine lead acid system. Not 24V and not 60W peak!!

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The PFC buck sounds good but is unfortunately not isolated.

gets softer and softer as its left to lie in water, and when softened , is easier to pump, so the ON/OFF/ON... thing takes on a new meaning of benefit.

Both false assumptions, pump goes on immediately with a timer button
After use, unless float storage is used for later pump out at sea. Then two pumps are used, the first being immediate.

I am surprised you dont have test results already of 16 to 20 sheets of double ply in a short closed loop test.