I used to be not too long ago tasked with doing a presentation on the advantages of power provides incorporating Digital Control to power non-linear loads, so I believed I'd share the content material with you.
A non-linear load is one that doesn't behave like an excellent resistor, in that the present drawn from the power supply is just not proportional to voltage and/or the preliminary currents are sometimes a lot greater than the score of the power supply.
These loads could cause issues for power provides, however are literally current in lots of functions:
Giant switched capacitor banks
Level of Load DC-DC converters
The principal concern from a power supply’s level of view is that the load can activate the internal over-current protection. Over-current protection (OCP) is an important feature for a power supply, however the power supply is often anticipated to get well mechanically with no guide intervention.
So to begin with, let’s have a look at the categories of OCP. There are a number of fundamental strategies used:
When an overload situation happens, the output voltage falls however the output present stays at a mounted degree. This kind of protection is just not properly suited to delivering peak loads as it may possibly lead to the power supply latching.
When the present drawn reaches the OCP restrict, the voltage falls, however this time the present decreases because the overload will get heavier. Once more this sort of protection is just not properly suited to delivering peak loads because it can lead to the power supply latching.
When the present drawn reaches the OCP restrict, the voltage falls. This time the output present will increase to a set most at quick circuit.
Fold ahead is properly suited to powering up motors, however requires heavier system load cabling to deal with the extra overload present.
On the OCP restrict, the power supply turns off for a quick interval after which mechanically tries to restart. Hiccup mode reduces the necessity for heavy cabling or pcb traces, and this sort of protection will be modified to ship a peak load.
With conventional Analog Control although, the OCP factors and restoration timing are mounted.
With Digital Control we are able to use software settings to alter the boundaries and timing; for instance we are able to set:
10s for an preliminary overload situation
60ms for heavy overloads
5ms for a quick circuit situation with restoration instances or 1 to 2 seconds
Let’s take an application instance of a discharged capacitor financial institution being switched onto an working power supply with Analog control.
The decrease (blue) hint is the power supply present; restarting twice with the power supply present restrict set at round 60A.
The high (gold) hint exhibits the output finally recovering, however tolerances with the hiccup mode timing might have prevented a full restoration.
This time the identical discharged capacitor financial institution is switched into a TDK-Lambda CFE400M supply incorporating digital control.
The blue hint is the present, gold hint is the output voltage
Using Digital Control, we are able to set the thresholds and timing precisely.
50A for 1.5ms (The quick circuit situation)
30A for 50ms (The over present situation)
Discover that there aren't any a number of makes an attempt to get well after the capacitor financial institution is utilized to the power supply.
Digital control can permit for exact and repeatable present limiting using load dependant timing. We aren't restricted to the worth of a timing capacitor which might change due to:
a) Batch tolerances
b) Getting older of the capacitor
c) Capacitor values altering with temperature
Digital control permits for straightforward tailoring for various functions with no bodily modification of the power supply is required. All adjustments are dealt with with software programming!