The Experts in High Precision Power Electronics

The Experts in High Precision Power Electronics

Bipolar high voltage power supply for storage chamber in a neutron EDM (nEDM) experiment

HCB 40-200000 MOD

02.10.2018 FuG Elektronik GmbH 3

General requirements to a bipolar power supplyA bipolar high voltage power supply shall deliver an adjustable high voltage at the output with an adjustment range from negative maximum to positive maximum and with a zero-crossing without any delay and with no regulation anomalies during zero-crossing.To fulfill these requirements, the power supply often needs full 4Q capability. It must be capable to handle the back-flow of energy from the load and to consume this energy.

Special requirements for the nEDM experiment- 200 (250) kV maximum output voltage- 100 ppm stability and temperature coefficient- 5 ppm (1V)residual ripple (p.-p.)- Current up to 200µA with measurement range 20µA (1 nA resolution)- Ramping speed about 1kV/s

Possible attempts and solutions with advantages and disadvantages- mechanical or electromechanical solution- Linear regulation - SMPS with voltage divider- SMPS with intrinsic voltage divider

Solution and problems to be solved- electrical principle- mechanical solution- problems and limitations


Bipolar:

At least first and third quadrant

has to be covered.

No time delay during zero-

crossing.


200 (250) kV maximum output voltage

100 ppm stability and temperature coefficient

5 ppm (1V)residual ripple (p.-p.)

Current up to 200µA with measurement range 20µA (1 nAresolution)

Low stored energy, fast recovery after discharge

Adjustable current limitation

Ramping speed about 1kV/s (5kV/s)

Digital programming (RS232 with optical fiber)

Special interlock (also via interface)


Mechanical or electromechanical solutionPublication Borisov, Yu. et al.,

Leningrad 1987: „200 kV

stabilized voltage source with

controlled polarity“

Polarity reversal switch

Hard to make for 200kV (oil insulation!)

No zero-passing without delay

Possible EMI due to motors and switches may

disturb measurement.

Noisy Motor-

Generator

Nevertheless – a

switch is necessary.


Linear regulation

No semiconductors for such high voltage

Serial connection of semiconductors?

Electron Tubes?

SMPS with voltage divider

High cross current (low efficiency, problem of heat dissipation)

Internal double of output voltage must be produced

Additional feature: full 4Q capability


Application example for 10kV


Application example for 200kV

SMPS with intrinsic voltage divider

Lower cross current

Internal voltage can be reduced


Electrical principle


Mechanical solution: First layer of molding material


Mechanical solution: Second layer & Multiplier


Mechanical solution: Output parts and measuring resistor


Mechanical solution: The ready product


Problems and limitations

Careful design of HV part is essential for function of power supply. Theoretical calculations and computer simulations are very helpful, but sometimes it needs corrections by practical experience.

Heat dissipation depends on voltage and nominal output power. Limits are given by thermal features of isolation material. Oil is an option but has other disadvantages.


Outlook

A new unit with 250kV is ordered.

Design is in work

Thank You!

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The Experts in High Precision Power Electronics