PLC Power Modul

This is the 24V power modul. It uses a 3rd party isolated DC/DC to support 24V “as is” and 5V isolated. It has protective diodes and capacitance for the 24V side. I could have needed more connectors for power distribution, but these boards are very small. As this is a PLC design we use. This should work on 12-24V and should be fine on the 18V batteries I use.

The remaining challenge is that the next modul is a Power Servo that require 8V or 12V depending on model. Even small, miniature Servo’s are a pain to switch on so these bigs ones will be a real issue. Learning from experience I believe it is wise to have a On/Off on the power to each servo as well as a current sensor and monitoring – which means I need to involve a MCU to do power management. This is all doable, but it add complexity/size.

The Power Modul above is the same as on the top, but without the isolated modul and with less internal power connectors. I can replace the Waterproof connector with an internal connector on 24V and adjust voltage out from 5 to 22V with 5A in peak, continious current. The DC/DC have a on/off switch, so all I need is to add a current sensor and an internal connector to a MCU board monitoring the PSU. This was a quick draft, so the modul is not ready. One issue here is that I use the same connectors for multiple things – that is OK’ich as we use TTL (5V), but it is very bad then we mix 5V, 8V, 12V and 24V – så I need to deal with that by using different connectors that cannot be intermixed by accident.

Protecting PSU’s from Motors are a big issue. I believe that the best protection is if the PSU have a fast, analogue trip that disconnect the PSU on over-voltage and -current. I can do thos in SW, but in this case I would like a analogue HW trip that need to be switched back on by SW. SW will be to slow for switching off. A misbehaving motor controller will typically trip and release the motor causing a break that release energy back on the 24V. This often result in a pulse that can break a few things. The PSU itself is the worst because as currend drop from xx to 0 it jump up in Voltage and uses a few “cycles” before it regulate it’s output at the same time as the Motor or coils misbehave. This needs to b experimental, but I think it will make the system safer.

Categories: PLC

Leave a Reply