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The high voltage supply "HV-3-16 Positive" is designed for supply high-voltage equipment demanding to voltage stability and voltage pulsation, like PMT grounded photochatode mode. The voltage supply is designed as transformer converter with six stages of voltage multiplication. For the excitation of the transformer used buck-voltage-fed full bridge schematic. The voltage supply has a modular design and a graphical LCD with a resolution of 128x64 pixel used to display measurements of voltage and parameters of the control loop. Output high voltage connector UHF-BJ type has positive polarity central pin.

Features:
Output voltage range 0.1÷3 kV
Output current 2 mA (3.0 kV) 3 mA (2.0 kV)
Short-term instability of output voltage 0.1%
Long-term instability of output voltage 0.5%
Input voltage 8÷12 V
Current consumption 30÷1800 mA
Voltage measurement accuracy 1.5%
The ratio of ripple at load current 2 mA 0.03%
Dimension 120x75x70 mm

Structural differences between the models:
HV3-16 HV4-10
External ADC 16 bit;
External voltage reference 4.096 V;
Total capacity of the high voltage filter 0.23 µF (3 kV)
Built-in controller ADC 10 bit;
Voltage reference +5.0 V (analog power);
Total capacity of the high voltage filter 0.035 µF (4 kV).

Schematic diagram:

From the developer.

The high voltage source positive polarity was developed to supply the PMT grounded photocathode mode. Initially, the control loop debug on the built-in controller 10-bit ADC, the control loop provided the voltage regulation accuracy 10 V, so there was a "lite" version of HV-4-10. Very pleased with the dynamic range of 100 V÷4 kV, which allowed to consider the product as a laboratory source of high-voltage power supply. Was tested protection of measuring circuits with emergency situations in high-voltage circuits. As it turned out the most vulnerable point of the source resistors in the feedback circuit. In the case of a long time discharge all semiconductors are able to work, but the resistors of the voltage divider are fail, the values of resistors drift unpredictable manner. In normal mode voltage drop on each resistor does not exceed 100V, as required by the resistors manufacturer specification.

The installation of an external Delta-Sigma ADC with external voltage reference allowed to raise accuracy of the control loop to 1V. To increase the performance of control loop, current measurement were removed. There was also increased capacity high voltage capacitors to filter the ripple after the voltage multiplier. As it turned out, the most powerful source of interference is not the high-voltage side and a step-down DC/DC converter to reduce the leakage inductance and radiated emissions, inductive energy storage is performed as a large toroidal core. The experience suggests that in the long term can be achieved precision of control to 0.1 (0.01%).

A few words about of high-voltage circuits design. Not to depend on structural features and availability of different models of high voltage transformers, it was decided to produce step-up transformers on their own. This is made of fiberglass rectangular profile which cut into frames, made frameless winding, latching layers by quick-drying lacquer and enveloped coil epoxy resin. TThe voltage multiplier and high-voltage circuit are coated organosilicon dielectric.


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