1. High precision, low ripple 3kV capacitor charger S. Blume, D. Gerber and J. Biela Laboratory for High Power Electronic Systems ETH Zürich

2. Pulse Modulator System for CLIC 2 Capacitor charging system Input voltage620-800V Output voltage2.4-3kV Power6x 40kW IsolationNon-isolated Capacitor charging system

3. Topology of Capacitor Charging System Boundary conduction mode operation Snubber capacitors to increase ZVS range Peak current I max =140 A Zero crossing of current saturating core 6-fold interleaving 3

4. I.Control of capacitor charging system 4

5. Control Structure of Capacitor Charging System Central control unit: Charging controller Interleaving controller Optical communication interface 5 Central control unit Single booster module

6. Charging controller Continuously calculates I req for V out,soll Limits I req =I max 4 different charging states 6

7. Interleaving Controller Phase shift measurement Zero crossing signals I set adapted to correct phase angle Settling time of 12 switching cycles selected 7

8. Six Fold Interleaved Capacitor Charging Charging of 3mF capacitor bank Peak current reduced to I max =50A, P charge =84kW Desired stable phase shifting achieved For CLIC with full 240kW charging power: t recharge =17.15ms <20ms 8

9. II.Repeatability analysis of capacitor charging system 9

10. Definition of Pulse to Pulse Repeatability Pulse to pulse repeatability (PPR): Deviation of pulses during flat-top Applies to a certain number of consecutive pulses Voltage precision, not accuracy Long term effects can be neglected 10 Charging voltage has most influence on modulator PPR [1] [1]: S. Blume, A. Jehle, Y. Schmid, and J. Biela, “Control of an active bouncer for an ultra precise 140 us-solid state modulator system,” in 17th European Conference on Power Electronics and Applications (EPE), Sept 2015, pp. 1–11.

11. Charging Precision Analysis Charging voltage step: ΔV cycle =14ppm Consecutive charging cycles must be considered Population size N=600000 Noise & quantization & jitter considered Last charging cycle due to external trigger integrated 11

12. Results of Precision Analysis 12 SNR of output voltage measurement essential With low SNR Vout higher σ and lower µ Filtering of output voltage measurement to increase SNR

13. Charging Precision with CLIC Parameters Noise measurements conducted for charging system Worst case values assumed for jitter and current measurement Operation range of CLIC modulator investigated Predicted standard deviation of charging voltage: σ Vout = 23.2 mV<10 ppm 13 Value Measured input voltage SNR68 dB Measured output voltage SNR82 dB Measured output voltage SNR with digital FIR filter 92.5 dB Current measurement SNR (assumed) 60 dB σ jitter (assumed)5 ns

14. Conclusion High precision, low ripple 3kV capacitor charger: 240kW charging system realized Stable interleaving operation achieved Precision analysis conducted based on SNR measurements Consecutive charging cycles considered σ Vout = 23.2 mV<10 ppm 14

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17. Data Transmission of Charging System Central control unit to six charging units 17

18. Repeatability Analysis of Single Pulse Unit Time dependent analysis Open loop control Entire flat-top interval Switching jitters have small influence Main capacitor voltage highest impact 18 ParameterMeanStandard deviation Unit Bouncer input voltage4500.0337V Main capacitor voltage 30000.045V