Transcript Anode Power Supply Simulation

DC Power Sources for the
High Power RF Amplifiers
By Rolf Wedberg
Review ESS Spoke RF Source
11 – 12 December 2012
Agenda
• DC Power supplies overview
• Anode power supply
– Main components
– Suppliers
– Expected performance (simulation)
– Simple simulation for ringing and envelope vs time
• Filament power supply
• Grids power supplies
– Control grid
– Screen grid (modulation)
• Summary
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DC Power Supplies
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DC Power Supplies: Overview
DC circuit
18 kV
Anode filter
18 kV
Anode filter
Anode power supply
Screen grid supply
1300V
1300V
Control grid supply
400V
400V
8.8VDC
8.8VDC
0
0
0
Filament power supply
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0
0
Filament power supply
1 Anode PS
2 Filament PS’s
2 Control-Grid PS’s
2 Screen-Grid PS’s
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Anode Power Supply
DC circuit
18 kV
Anode filter
18 kV
Anode filter
Anode power supply
Screen grid supply
1300V
1300V
Control grid supply
400V
400V
8.8VDC
8.8VDC
0
0
0
0
Filament power supply
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0
Filament power supply
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Anode Power Supply: Main Components
To the other anode
18kV
Series switch
+
-
5
-
+
To anode
S
DC current monitor
dV/dt monitor
Crowbar
Pulse current monitor
Optical f ibre
31 kW
I3
130 uF
Volt. div ider
From saf ety control
From control
To series switch control
1
3 phase 400 V
0
2
Capacitor charger
0
To saf ety control
0
0
0
Anode supply
Two Outputs
In each output
For both outputs
Vmax = 18 kV
Imax = 18 A
Series-switches
dI/dt limiting with inductors
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pulse width 3.5 ms
pulse rate 14 Hz
Maximum voltage droop 1 kV
Capacitor charger with voltage and power regulation
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Anode Power Supply: Suppliers
• These components are not state-of-the-art
• Readily available
• Some examples:
– Capacitor Charger: FuG , TECHNIX
– Capacitor: Nokian, Hivolt capacitors, ABB and others
– Switches: Behlke, DTI and Gihomeq AB
– Coils: Unitrafo, Transform and others
– Assembly: High Voltage AB, JACO industries and others
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Anode Power Supply: Performance
• Main problems:
– Series switches current capability
– Output voltage ringing due to the inductive outputs
• To check performance
Anode Power Supply Simulation
– A simple simulation has been run to observe behaviour and ringing of
the output voltage of the anode power supply
– Cable length, filters, cavity etc. have been included
– Assumptions:
• Tetrode considered as a switch
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Anode Power Supply: Simplified circuit
The equivalent electric circuit used for the simulations:
Anode power supply
L5
R2
5
High voltage cable Anode filter
L8
R3
R4
700uH
10m
C4
130uF
16uH
L6 Anode DC connection
R5
10m
25uH
10m
C3
100pF
Ccable
1n
0
Anode filter
L7
0
0.1uH
C2
100pF
0
0
Waveguide
R8
R1
0.1 Anode cavity
Output power coupler
T1
Q value app. 300
L1
5nH
L2
1n
L4
C5
5nH
41pF
L3
1n
0.1
Input power coupler
Spoke cavity
R6
0.1u
K K2
K_Linear L3 and L4
COUPLING = 1
R9
1MEG
0
0
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C1
41pF
K1
K_Linear L1 and L2
COUPLING = 0.99
R7
0.1
0
Signalgenerator
+
-
V1
VOFF = 0
VAMPL = 4
FREQ = 351.659MEG
AC =
0
Tetrode
S1
0
+
-
S
VOFF = -1
VON = 1.0V
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-6 kV -4 kV -2 kV
0
2 kV
4 kV
6 kV
Anode Power Supply: Transient regime
0 µs
10 µs
20 µs
30 µs
40 µs
50 µs
Order-of-magnitude estimate shows that the tetrode cavity voltage is stabilized after 20 us
Enough time for the amplifier to be stable on every pulse
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Filament Power Supply
DC circuit
18 kV
Anode filter
18 kV
Anode filter
Anode power supply
Screen grid supply
1300V
1300V
Control grid supply
400V
400V
8.8VDC
8.8VDC
0
0
0
Filament power supply
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0
0
Filament power supply
Vmax 15V
Imax 200 A
Ramping for 8 min
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Grids Power Supplies
DC circuit
18 kV
Anode filter
18 kV
Anode filter
Anode power supply
Screen grid supply
1300V
1300V
Control grid supply
400V
400V
8.8VDC
8.8VDC
0
0
0
Control grid
0
0
Filament power supply
Filament power supply
Screen grid
• Max. output:
• Max. output:
• Voltage 1300 VDC
• Voltage 400 VDC
• Current 0.7 A
• Current 4 A
• Negative terminal grounded
• Positive terminal grounded
• i.e FuG or Technix
• i.e Delta, FuG or Technix
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Summary
• The Anode Power supply:
– can be made of an assembly of commercial components
– is special to use the power grid in an efficient way and designed for
the pulsed load
• Grid and filament power supplies are ”off the shelf” commercial power
supplies
Thank you Rocio and Vitaliy for help with Power Point
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Control Grid Connection
Thales recommended control grid connection.
D2
200VDC
V1
0
RBleed
50 to 800 Ohm
D1
R1
R2
1k
1k
0
0
If positiv e switch of f RF within 100 us and control grid power supply in 20 ms.
The control grid voltage will become more negative during RFpulse. Bootstrapping?
The power supply is working with high output current into the
bleeder resistor so that it may sink current during the RF-pulse.
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Screen-grid Connection: Modulation
Alternative without switch
Alternative with switch
Screen grid supply
-
RF grounding
R14
18k
1300V
RF grounding1
+
R13
18k
+
-
S
S1
1300V
Screen grid supply
0
0
0
0
The Power Supply needs protection when there is an arc from the
anode. The Screen grid may be used to modulate, turn off anode
current between RF pulses.
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