Transcript Cavity voltage control outputs

8th ESLS RF Meeting – 29th, 30th Sep. 2004
Low Level RF of ALBA
(A preliminary study)
Hooman Hassanzadegan
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LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
General view of the RF system
Cavity voltage (Vprobe)
Incident and reflected powers
Master
Oscillator
(500MHz)
MO
Circulator
LLRF system
Cavity
Drive
signal
Hi-power
Amplifier
Tuner
Tuning control
Control
system
Beam
HVPS
High Voltage
Power Supply
The task of the LLRF is the regulation of the amplitude, frequency and
phase of the RF wave.
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LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
LLRF - hardware
 Sensors for the incident, reflected and cavity power (Pinc, Prefl, Pprobe)
 The required hardware for the isolation and amplification of the RF
signals
 The required Digital / Analog circuits for regulation, interfacing, ADC,
DAC, signal processing, etc.
 Drive power amplifier
 PIN diode
 Master oscillator
 Other modules including auxiliary power supplies, PLL, Interlock, etc.
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LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
Amplitude and phase regulation loops
Master
Oscillator
Control
System
Drive
Signal
Phase Regulation
Master
Oscillator
Control
System
Drive
Signal
Phase
Regulation
Amplitude
Regulation
Motor
Control
Mech. Phase Shifter
Variable
Attenuator
Amplitude
Control
Phase
Control
Elec. Phase Shifter
RF Switch
Mech. Phase Shifter
Pre - amplifier
Amplitude Regulation
Klystron
Amplifier
Klystron
Amplifier
Cavity
a) Amplitude Regulation
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Cavity
b) Phase Regulation
LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
I-Q demodulator and rotation matrix
Demodulation:
V (t )  I .Cos(t )  Q.Sin (t )
I  Aprobe  Cos( probe   MO )

Q  Aprobe  Sin ( probe   MO )
Q
Aprobe
phase
Modulation:
I
Aprobe  I 2  Q 2
 probe   MO  arctan 2(Q I )
Rotation matrix:
I to I
+
Iin
 I out 
Q  
 out 
Cos
A
 Sin
 Sin   I in 

Cos  Qin 
Iout
I to Q
-
Q to I
+
Qin
Q to Q
5
Qout
+
LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
General suggestions for ALBA LLRF
 I-Q demodulation is more favourable, because two identical
regulators will be used acting on baseband signals with wider
phase control range compared to the traditional amplitudephase loops.
 It’s more desirable to use digital electronics which provides
more flexibility, possibility of future changes by the software,
better diagnostics and higher functionality compared to
analog electronics.
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LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
Amplitude / phase control (analog and digital)
Digital module
Ethernet
Processor board (VME processor or Industrial PC)
GUI
Transition boards
IP
DAC
DAC
DAC
DAC
ADC
Interlock
Analog module
Cosθ, Sinθ
FF
Gain
Set
Probe
I+
I-Q mod
I-Q dem
Rotation Matrix
IQ+
Q-
Pprobe
MO
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500 MHz
Klystron Amplifier
Cavity
LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
Amplitude / phase control (all digital)
Interface
Digital
Learn
+
RF
+
Delay
Amplifier
Set
Points
PID
+
+
2x2
Cavity
Dig.
to RF
+
Feed
Forward
Klystron
Control
IQ to
ρφ
ρφ
Set
points
IQ to
ρφ
Resonance
Control
RF to
Dig.
RF to
Dig.
RF to
Dig.
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Forward
Reflected
Cavity
LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
Tuner control
Cavity RF
IQ demodulator
Drive RF
I
Q
Cavity tuner control:
 An IQ demodulator detects the phase difference between the
drive RF and the actual cavity voltage
 The LLRF system drives the phase using the relation Arctan(Q/I)
 The LLRF drives the cavity to maintain the desired phase
difference
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LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
Inputs / Outputs for LLRF controls
Cavity voltage control inputs:
Cavity tuner control inputs:
1.
Reference RF
1.
Cavity voltage
2.
Cavity Voltage
2.
Derive RF
3.
Cavity In-phase setpoint (FB)
4.
Cavity Quadrature setpoint (FB)
Cavity tuner control outputs:
5.
IQ regulator gains
1.
Cavity tuning In-phase (I)
6.
Cavity In-phase setpoint (FF)
2.
Cavity tuning Quadrature (Q)
7.
Cavity Quadrature setpoint (FF)
8.
Rotation matrix parameters
Cavity voltage control outputs:
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1.
Power amplifier drive
2.
Cavity voltage In-phase monitor
3.
Cavity voltage Quadrature monitor
Electrical and performance
specifications of the Input /
Output signals still have to
be defined.
LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
The first step – IQ demodulator
 We’ll need it with both Digital and Analog Reg.
 Detailed design is available
 Comparably easy to build
 Can be tested with a function generator
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LLRF of ALBA
8th ESLS RF Meeting – 29th, 30th Sep. 2004
The next steps
1.
I-Q demodulator (AD8348 from Analog Devices)
- Can be designed and made at CELLS
- Test with a function generator
2.
Other parts of the “Analog module”
3.
ADC, DAC and processor boards (“Digital Module”)
- Off the shelf, but still need programming
- will be done in collaboration with the Control Group
4.
Test with simulated system
5.
Interfacing with the control system and GUI
- Will be done mainly by the Control Group
6.
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Commissioning and trouble-shooting
LLRF of ALBA