MAGNET POWER SUPPLY SYSTEM 9100
57
DANFYSIK A/S - DENMARK.
4.7.3
Aux power FAN
The fan and will go on if the MPS is power on and off if the MPS is off controlled by the
signal FAN CONTROL.
4.7.4
Aux power primary
Supply voltages -5 V and +20 V is generated by U3 and T1 respectively.
4.8
DCCT transducer
DCCT current transducer measures the output current and controls the current stability in the
power supply. The output signal from the device is a current (2000 times less than the output
current). The current generates a voltage of approximately 1 V across a burden resistor when
the output current is 200 A.
The 1 V signal developed across the burden resistor R519 on the control module, is measured
by A501B coupled as a differential amplifier and scaled to give 1 V output for an output
current of 200 A.
4.9
Bipolar output stage (H-Brigde)
The bipolar power supply can be achieved by using the standard unipolar system as the power
platform added with an analogue bipolar output stage. It consists of a loop control and two
output H-bridge stages. The system will be able to deliver a bipolar output current Io also
around zero. The output MOSFET amplifier is therefore designed to work in two modes, linear
and saturated. As long as the control voltage signal Vpwr < Vmin, the output amplifier works
in linear mode and when Vpwr>Vmin the output works in saturated mode.
When the bipolar output stage is connected to the control module, a bipolar mode signal is
generated to switch the control module working on the bipolar mode.
The control loop circuit is constructed around A1, A2, A3, A4 and A5.
The one half of the linear analogue output stage will be build around Q5, Q6, Q2 and Q12. The
corresponding one half of H-bridge interface circuit is constructed around MOSFET Q1, Q2,
Q3 and Q4.
