main functions of kV and mA regulation. The DSP provides the digital circuitry to
monitor report and latch fault conditions. The DSP works together with ADCs, DACs to
coordinate the control, calibration and to implement Remote (RS 232 or other) control
via serial communications. The DSP implements a programmable arc counter and also
disables the kV regulator with the goal of quenching the arc. Additional functions on the
regulator card include precision references, kV and mA ref ramp, turn on and turn off
and on card low voltage regulators.
6.2.2.
kV Regulator
The kV regulator is responsible for regulating the voltage of the power supplies main
output. It is implemented by a voltage error amplifier which compares a reference kV ref
to the feedback level kV FB. The reference level is set to zero volts whenever the HV in
not enabled. This level is then ramped up by hardware or SW to the anticipated level
that the power supplies is programmed to go to. The ramp-up or slew rate should be
selectable from SW command via serial interface. The slew rates should be 0-10sec to
full scale. The ramp-up generator is enabled by HV enable/Arc Rollback, a signal from
control logic in DSP. When the enable signal goes false, the ramp-down is immediate.
This enable signal will also enable/disable the PWM or the drive inverter for the high
voltage. The kV error amplifier system is connected to PWM Controller. The PWM
outputs are used to drive the gates of the HV inverter.
The regulator inputs/outputs are normalized to 10V=Full scale. These circuits should be
able to operate linearly with >=11V range for testing and burn in purposes (110% full
scale). The reference level signal path must be designed such that it can be sourced
from externally applied analog voltages or optionally from a analog voltage created as a
result of a remote control serial command (e.g. DAC). This implies an analog switch
selecting the two paths that may be controlled by Local Analog/Remote control jumper.
Also to facilitate trouble shooting a jumper for selecting closed loop or open loop control
should be provided. The 2 pin headers maybe used for test purposes and produces HV
output controlled only by the kV reference independent of the kV feedback.
The kV regulator provides the following analog monitors signals:
KV monitor: 0 to +10V = 0 to Maximum Rated kV full scale voltage output
6.2.3.
mA Regulator
The mA regulator is very similar to the kV regulator architecture but controls the filament
inverter. Normal function is to operate in Emission Current Regulation (ECR) mode by
controlling the HV output current through regulation of the filament inverter. When it is
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