How much current will you be drawing from the rectifier/smoothing?

Around 2A max.

 

Around 2A max.

With a 22uF capacitor there will be 3-4V of ripple on the output at 2A but that would probably be OK.

 

With a 22uF capacitor there will be 3-4V of ripple on the output at 2A but that would probably be OK.

I’ve got a 10uF 500V electrolytic cap so will that be ok to use?

 

I’ve got a 10uF 500V electrolytic cap so will that be ok to use?

It will double the ripple voltage.

 

Fair enough but will the rectification and smoothing process remove that noise effectively? Also is it ok to use an electrolytic cap in this case?

What the rectification does, at light loads, is charge the filter capacitors to the peak value of that part of the waveform. Thus the regulation suffers because the no-load voltage is higher than theory would predict. So the solution is to avoid that instability at the rising edges. Not simple, by the way.

 

What the rectification does, at light loads, is charge the filter capacitors to the peak value of that part of the waveform. Thus the regulation suffers because the no-load voltage is higher than theory would predict. So the solution is to avoid that instability at the rising edges. Not simple, by the way.

Well that I presume is a feature of the design and so little I can do about it. I take your point though.

I notice on the Chopper board that the GND in and not connected to the V0 out unlike what I expected so if I want to connect all the 0V points on the circuit I.e. the negative on the Arduino, the buck converter and the Chopper, do I need to connect to the GND terminal and ignore the 0V as a reliable ground?

 

I notice on the Chopper board that the GND in and not connected to the V0 out unlike what I expected so if I want to connect all the 0V points on the circuit I.e. the negative on the Arduino, the buck converter and the Chopper, do I need to connect to the GND terminal and ignore the 0V as a reliable ground?

It will probably matter how you connect them together. A star ground point would be good.

 

It will probably matter how you connect them together. A star ground point would be good.

It is entirely possible that the circuits on the various devices are not common between any input and any output segments. Mostly there is no reason that they have to be. I have seen some rather expensive destruction caused by connecting things that were not common as though they were. Thus understanding the circuit before making random connections is not recommended.

 

I think I'm going to use several ground points, the main one being the - of the battery at the GND terminal of the DC Chopper (see pics 1&2). The 8V input to the Arduino from the Buck Converter will I hope be happy with its + and - from the Converter. However, the 0V from the DC Chopper output does not connect to the GND (isolated secondary winding) so I'm not sure where best to connect the 0V from the rectifier to - GND also? You may see a whole different way to connect the negs and grounds.

I attach the measured rectified output now that I have assembled the rectifier and cap. I used a 30uF (500V) in the end and the 12V ripple showing on the measurements is due I guess to some small remaining spikes or instabilities that I hope won't affect the H bridge and MOSFETs that will use it. This is the supposed '50V' output so once rectified noticeably higher at around 72V.

Once I switch off the battery power to the Chopper, the cap remains at that voltage for a long time so can I use say a 1M (0.25W) resistor to bleed it down over say 30s. Not so much a problem at under 100V but if I use 400V then I would rather it was dissipated early.