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High Voltage Power Supplies With Pulsed Loads»

This is a group of excellent papers relating to the design of high voltage power supplies with pulsed loads, such as radar. An ingenious power conversion topology is described.

A Two Stage Power Converter Topology for High Voltage DC Power Supplies Under Pulsed Loads: Abstract -: High voltage power supplies for radar applications are investigated, which are subjected to high frequency pulsed load
(above 100 kHz) with stringent specifications (regulation < 0.01%, efficiency >85%, droop < 0.5 V/micro-sec.). As good
regulation and stable operation requires the converter to be switched at much higher frequency than the pulse load
frequency, transformer poses serious problems of insulation failure and higher losses. The solution to this problem as a
single stage converter is very difficult. In converters operating at high voltage and high frequency, the insulation failure
of high voltage transformer is very common. Skin and proximity effect result in higher power losses. Because of high turns
ratio, the winding capacitance results in delays and current spikes. Hence a two-stage converter has been proposed.

A Two Level Power Conversion for High Voltage DC Power Supply for Pulse Load Applications Abstract -
High voltage power supply with pulse load (125 KHz and 10 % duty cycle) condition is investigated
which is of interest for applications like radar power supplies with output voltage of 22 KV. The
performance specifications with this type of power supplies are very stringent demanding tight
regulation (< 0.01 %) and high efficiency (> 85%). The solution to this problem as a single stage
converter is very difficult. In converters operating at high voltage and high frequency the insulation
failure of high voltage transformer is very common. Skin and proximity effect result in higher power
losses. Because of high turn’s ratio, the winding capacitance results in delays and large current spikes.
Hence a two level converter has been contemplated. One stage of it, namely, Base power supply
(BPS), operates at low frequency and produces majority of the output voltage and power. The other
one, namely, fast power supply (FPS), operating at high frequency and low output voltage supplies the
remaining power and takes care of the transient variations of line and load. The final output voltage is
obtained as sum of the outputs of BPS & FPS. The combination of the two stages can satisfy the pulse
load specifications. Each of the BPS & FPS use phase modulated-series resonant converter as the
power-processing unit with zero voltage switching (ZVS). The analysis of the voltage and power
division between BPS & FPS has been done for the proposed topology. It is simulated for a power
level of 600 watts and an output voltage of 1 KV as a prototype. It has been studied under various
operating conditions of line and load. Simulation results are validated by experimental results.

Input Voltage Modulated High Voltage DC Power Supply Topology for Pulsed Load Applications Abstract - High voltage power supplies for radar applications
are investigated which are subjected to pulsed load with
stringent specifications. In the proposed solution, power
conversion is done in two stages. A low power-high frequency
converter modulates the input voltage of a high power-low
frequency converter. This method satisfies all the performance
specifications and takes care of the critical aspects of HV
transformer.

Average Current Mode Control of High Voltage DC Power Supply for Pulsed Load Application Abstract - High voltage power supplies with pulse load (125
KHZ and 10 % duty cycle) is investigated which are of interest
for applications like radar power supplies with output voltage of
22KV. The performance specifications with this type of power
supplies are very stringent demanding tight regulation (< 0.01 %)
and high efficiency (>85 %). This paper proposes a methodology
to tackle the problems associated with this type of application.
Phase-modulated series resonant converter with ZVS is used as
the power converter. Average value of the rectified tank current
is controlled to regulate the output voltage. Synchronization of
converter switching with load pulses enables the converter to
switch at half the load switching frequency. Low switching
frequency helps in ensuring safety of HV transformer insulation
and reduction of losses due to skin & proximity effect. Average
current mode control gives excellent dynamic response with
simple closed loop design.

Comparison of High Voltage DC Power Supply Topologies for Pulsed Load Applications Abstract - High voltage power supplies for radar applications are investigated, which are subjected to pulsed load (125 kHz and 10% duty cycle) with stringent specifications (<0.01% regulation, efficiency>85%, droop<0.5V/micro-sec.). As the converter needs to be switched at much higher frequency than the pulse load frequency, transformer poses serious problems of insulation failure and higher losses. Two power converter topologies are presented, one with input voltage modulation (IVM) and the other with output voltage modulation (OVM). In each of the topologies, power conversion is done in two stages to take care of the critical aspects of the HV transformer and to satisfy all the performance specifications. Both the topologies are critically evaluated for their performance and their relative merits and demerits are discussed.

High Voltage DC Power Supply Topology for Pulsed Load Applications with Converter Switching Synchronized to Load Pulses Abstract - High voltage power supplies for radar applications are investigated, which are subjected to pulsed load (125 kHz and 10% duty cycle) with stringent specifications (<0.01% regulation, efficiency>85%, droop<0.5V/micro-sec.). As good regulation and stable operation requires the converter to be switched at much higher frequency than the pulse load frequency, transformer poses serious problems of insulation failure and higher losses. This paper proposes a methodology to tackle the problems associated with this type of application. Synchronization of converter switching with load pulses enables the converter to switch at half the load switching frequency. Low switching frequency helps in ensuring safety of HV transformer insulation and reduction of losses due to skin & proximity effect. Phase-modulated series resonant converter with ZVS is used as the power converter.