MAGNET POWER SUPPLY SYSTEM 7000
38
DANFYSIK A/S - DK 4040 JYLLINGE - DENMARK.
4.3.18
Current Regulation
The ERROR amplifier U301A amplifies the ERROR signal from the summing point.
The output current is converted to 0.1 ampere in the DCCT and it is measured as a voltage
across the high precision, very low drift 10
S
burden resistor. This voltage is converted to a
current using the resistors R304. This negative current is then compared with the positive
current in a sum point, and the difference is fed to the amplifier U301 an LT1112. The
amplification factor of U301 and its frequency response can vary with the specification for
each power supply.
The main task of the Regulation circuitry is to produce a regulated signal to the power output
stage from the "ERROR" amplifier.
The Regulation circuit contains the following main functions:
-
Current loop Amplifiers/compensation
-
Current Error Amplifier
Due to the output load DCCT compensation, is it possible to connect many different loads to
the output terminals of the power supply still keeping the regulation loop stable. On special
requirement and loads, fine tune some loop components are necessary. Please see the change
notes in chapter 8 for possible change in component values.
The regulation principle can easiest be illustrated by looking at the two major criteria for the
loop.
1- Inner loop for Power Amplifier
2- Outer loop for ppm stabilisation.
+ Out
Regulation principle for MPS SYSTEM 7000
Power Amplifier
DCCT Filter
PNP
Outer LOOP
A1
DCCT 1
+
-
+
-
Inner LOOP
A2
NPN
Driver
The figure shows the Principia of the two-loop regulation.
