3.1. High voltage supply
For the high voltage generation a patented highly efficient resonance converter circuit is used, which provides a sinusoidal
voltage with low harmonics for the HV-transformer. For the high voltage rectification high speed HV-diodes are used.
A high-voltage switch, connected to the rectifier allows the selection of the polarity. The consecutive active HV-filter damps the
residual ripple and ensures low ripple and noise values as well as the stability of the output voltage. A precision voltage divider is
integrated in the HV-filter to provide a feedback voltage for the output voltage control, an additional voltage divider supplies the
signal for the maximum voltage monitoring. A precision control amplifier compares the feedback voltage with the set value given
by the DAC (remote control) or the potentiometer (manual control). Signals for the control of the resonance converter and the
stabilizer circuit are derived from the result of the comparison. The two-stage layout of the control circuit results in an output
voltage, stabilized with very high precision to the set point.
Separate security circuits prevent exceeding the front-panel switch settings for the current I
max
and voltage V
max
limits. A
monitoring circuit prevents malfunction caused by low supply voltage.
The internal error detection logic evaluates the corresponding error signals and the external INHIBIT signal and impacts the
output voltage according to the setup. In addition this allows the detection of short over currents due to single flashovers.
3.2. Digital control unit
A micro controller handles all internal control, evaluation and calibration functions. The actual voltages and currents are read
cyclically by an ADC with a connected multiplexer. The readings are processed and displayed on the 4 digit LCD. The current and
voltage hardware limits are retrieved cyclically several times per second. A reference voltage source provides a precise voltage
reference for the ADC and the control voltage for the manual operation mode of the unit. In the computer controlled mode the
set values for the corresponding channels are generated by a 16-Bit DAC.
3.3. Filter
A special feature of the unit is a tuned filtering concept, which prevents perturbation of the unit by external electromagnetic
radiation, as well as the emittance of interferences by the module. A filtering network for the supply voltages is located next to
their connectors, the converter circuits of the individual channels are protected by additional filters. The high-voltage filters are
housed in individual metal enclosures to shield even minimal interference radiation.
EHQ High Voltage Power Supply series | Last changed on: 11.05.2020 |
www.iseg-hv.com
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