Solid State Modulators: Efficiency Considerations focussing on SiC Devices

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Solid State Modulators

Efficiency Considerations focussing on SiC Devices

Author(s):

Biela, Jürgen; Stathis, Spyridon; Jaritz, Michael; Blume, Sebastian Publication Date:

2019-11-28 Permanent Link:

https://doi.org/10.3929/ethz-b-000381983

Rights / License:

In Copyright - Non-Commercial Use Permitted

This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use.

ETH Library

Eidgenössische Technische Hochschule Zürich

Swiss Federal Institute of Technology Zurich Laboratory for High

Power Electronic Systems

Solid State Modulators

– Efficiency Considerations focussing on SiC Devices – J. Biela, S. Stathis, M. Jaritz, and S. Blume

www.hpe.ee.ethz.ch / jbiela@ethz.ch

High Power

Typical Topology of Solid State Pulse Modulator Systems

t V

V

t t

V

V

t DC

AC DC Energy Storage

DC

Klystron Load

Pulse Modulator

Pulse

Pulse

Constant Power Pulsed Power

Medium Voltage

Grid ⎧⎪⎪⎪⎨⎪⎪⎪⎩

Sometimes integrated

Pulse Voltage Capacitor Bank

Intermediate Buffer 400V or MV

AC/DC rectifier unit

DC/DC converter for charging C-bank / voltage adaption

Pulse generation unit

Load e.g. klystron

High Power

Typical Topology of Solid State Pulse Modulator Systems

DC

AC Energy Storage

Pulse Modulator Medium Voltage Grid

DC

DC

Typical Isolation

t V

V

t t

V

V

t Klystron

Load

Pulse

Pulse

Pulse Voltage Capacitor Bank

Intermediate Buffer 400V or MV

Grounded klystron load

IIsolation with 50Hz transformer or

IIsolated DC-DC converter

High Power

29 MW ^(35MW) /140 µs Modulator for CLIC

– System Efficiency –

High Power

CLIC System Specifications

(c)FT

TA BC2 delay loop

2.5 km

decelerator, 24 sectors of 878 m 819 klystrons 15 MW, 142 µs

CR2 CR1 circumferences delay loop 73 m CR1 293 m CR2 439 m

2.75kmBDS TA IP

BC2

delay loop 2.5 km

819 klystrons 15 MW, 142 µs

drive beam accelerator 2.4 GeV, 1.0 GHz

CR2 CR1

2.75kmBDS

48.3 km CR combiner ring

TA turnaround DR damping ring PDR predamping ring BC bunch compressor BDS beam delivery system IP interaction point dump

drive beam accelerator 2.4 GeV, 1.0 GHz

BC1

Drive Beam

Main Beam

e⁺ injector, 2.86 GeV e+

PDR 389 m e+

DR 427 m booster linac

2.86 to 9 GeV

e⁺ main linac

e^– injector,

2.86 GeV e–

PDR 389 m

e^– DR 427 m e^– main linac, 12 GHz, 100 MV/m, 21 km Output voltage 150. . .180 kV

Output power (pulsed) 29 MW(- 35 MW)

Flat-top length 140 µs

Flat-top stability (FTS) <0.85 %

Rise time <3 µs

Settling time <8 µs

Repetition rate 50 Hz

Average output power 203 kW(- 245 kW)

Pulse to pulse repeatab. <100 ppm

High Power

CLIC Solid State Modulator – System Overview

DC

AC DC

DC 3kV

450V 750V

0-300V

Klystron Load Switching Unit

DC

DC

400V Voltage

Grid

Active Bouncer

-180kV

0V 300V

-180kV AC/ DC Unit

750V 3kV 3kV

Interleaved Boost Converter

400V

3kV

Matrix Transformer

High Power

CLIC Modulator – Grid/Isolation Transformer

DC

AC DC

DC DC

DC

Grid

Isolation Transformer PFC

Rectifier Boost Converter (Droop Compensation)Bouncer Switching Unit Pulse Transformer Voltage 3×400 V to 3×400 V @ 250 kVA

Core material Silicon steel

Winding material Aluminium

Weight 890 kg

Efficiency 98.8 %

(PCore=700 W&PWdg=2.3 kW)

Higher efficiency

IBetter core material E.g. Amorphous(PCore−60%) ICopper winding Higher conductivity(P_Wdg−35%) IEfficiency á≈99.2 %(Estimated)

(Larger volumeáHigher efficiency)

High Power

CLIC Modulator – AC/DC Converter Efficiency

+

+

DC

AC DC

DC DC

DC

Grid

Isolation Transformer PFC

Rectifier Boost Converter (Droop Compensation)Bouncer Switching Unit Pulse Transformer Type (B&R) ACOPOSmulti 8BVP1650

Topology 2-level PFC-rectifier

Switches 1.2 kV Si IGBTs

Voltage conversion 400 V_AC→750 V_DC(620 V – 800 V)

Efficiency 97.47 %

Higher efficiency

I1.2 kV SiC MOSFETs LowerPCond&PSW

IOptimised design E.g. higher volume / lowerfSW

IEfficiency á≈99 %

High Power

CLIC Modulator – Boost Converter Basic Operation

...

...

T₁ T₂ T₃ T₄ T₅

t

I_L

t

V_DCv_Cd,tot v_Cs,tot L

I_L

ZVSoff ZVS on

S₁ S_n

I_max

I_min

DC

AC DC

DC DC

DC

Grid

Isolation Transformer PFC

Rectifier Boost Converter (Droop Compensation)Bouncer Switching Unit Pulse Transformer Input voltage 600 V – 800 V

Output voltage 3 kV

Switching frequency 70 kHz – 240 kHz

Output power 40 kW

650 V Si MOSFETs 8 in series áC_s/Rfor balancing

Boundary cond. mode

6-fold interleaving á6×40 kW

High Power

CLIC Modulator – Boost Converter Efficiency

...

...

S₁ S_n

Fans Inductor

PCB with isolated gate drives Output capacitors

Input capacitors

HV output

Power input

Input fuse

MOSFET Conduction

58%

MOSFET Switching 6%

Diode Conduction

20%

Diode Switching

3%

Boost Inductor

11%

Snubber Capacitor 2%

Nom. voltages 750 V→3 kV

Output power 40 kW

Switching frequency 70 kHz – 240 kHz

8×650 V Si MOSFETs 2×Infineon IPZ65R019C7

4×1.2 kV diodes Microsemi APT75DQ120B

Efficiency 97.2 %

High Power

CLIC Modulator – "SiC" Boost Converter

...

...

S₁ S_n

W 100 W 200 W 300 W 400 W 500 W 600 W 700 W

MOSFET Conduction MOSFET

Switching Diode Conduction Diode

Switching Si-based Converter

SiC-based Converter MOSFET

Conduction 46%

MOSFET Switching 3%

Diode Conduction

22%

Boost Inductor 25%

Snubber Capacitor 4%

Voltages 750 V→3 kV

Switching frequency 70 kHz – 240 kHz

Higher efficiency

I4×1.2 kV SiC MOSFETs 2×C3M0016120K

I4×1.2 kV SiC Diodes 2×IDW40G120C5B

IEfficiency ≈98.6 % (Old: 97.2 %)

High Power

CLIC Modulator – Switching Unit

Switching Losses

87% Conduct.

Losses 13%

DC

AC DC

DC DC

DC

Grid

Isolation Transformer PFC

Rectifier Boost Converter (Droop Compensation)Bouncer Switching Unit Pulse Transformer ABB StakPak 4.5 kV / max. 3 kA (pulsed)

(5SNA1250B450300)

Active reset switch

4 units in parallel

Pulse current 4×2.4 kA (@P_P=29 MW )

Efficiency 98.6 %(Switching losses: 87% ofPtot)

Higher efficiency

ISemiconductors SiC MOSFETs

(assumption: 1.2 kV devices) (4 in series / 3 parallel)

IEfficiency á 99.5 %

High Power

CLIC Modulator – Bouncer

V_b,out V_main

+

300V 3kV

V_total DV=300V

Lb

C_main

Active Bouncer Module D_LS

D_HS S_HS

S_LS S_SC

DC

AC DC

DC DC

DC

Grid

Isolation Transformer PFC

Rectifier Boost Converter (Droop Compensation)Bouncer Switching Unit Pulse Transformer Output voltage 0. . .300 V (10 % droop)

Input voltage 450 V

24-fold interleaving

Ultra low ripple

Semiconductors IGBTs

High Power

CLIC Modulator – Bouncer Operating Principle

L_b C_main

Active Bouncer Module D_LS

D_HS S_HS

S_LS S_SC

Wait for trigger

Pulse Resonant Interpulse

Recharging

Wait for next pulse Pre-

charge

i

625A

V

V

450V

t_k

V

}

3.0kV 2.7kV

}

Pre-charge

V_Bout shortened

Output voltage 0. . .300 V

Input voltage 450 V

Output current (pulse) >600 A (per module)

High Power

CLIC Modulator – Bouncer Components

L_b C_main

Active Bouncer Module D_LS

D_HS S_HS

S_LS S_SC

Short circuit switch Buck-boost switch

Control board

Output voltage 0. . .300 V

Input voltage 450 V

4×6-fold interleaving

Switching frequency 100 kHz

Per module:

ISLS-IGBTs 2×IGW50N65H5

IDLS-Diodes 4×IDW40E65D1

ISHS-IGBTs (w. diode) 6×IKW50N65F5

ISSC-IGBTs (w. diode) 6×IKW50N65F5

IInductorLb= 26 µH 4×Metglas AMCC32

High Power

CLIC Modulator – Bouncer Efficiency

HS IGBTs conduct.

7%

HS IGBTs switching 51%

LS diodes LS IGBTs 4% 14%

SC IGBTs 3%

HS diodes 3%

Inductor losses

18%

L_b C_main

Active Bouncer Module D_LS

D_HS S_HS

S_LS S_SC

i_b

625A

t_k

With IGBTs

ITotal AVG losses 1.56 kW

IModule efficiency 91.0 %Bouncer-Level áEfficiency 99.4 %System-Level

High Power

CLIC Modulator – SiC Bouncer Efficiency

HS SW conduction

12%

HS SW switching

8%

LS diodes 27%

LS SW 9%

SC SW 4%

HS diodes 5%

Inductor losses 35%

L_b C_main

Active Bouncer Module D_LS

D_HS S_HS

S_LS S_SC

W 200W 400W 600W 800W

HS switch conduction HS switch

switching LS diodes LS switch SC switch Si-based converter SiC-based converter

With IGBTs

ITotal AVG losses 1.56 kW

IModule efficiency 91.0 %Bouncer-Level áEfficiency 99.4 %System-Level

With SiC MOSFETs

ITotal AVG losses 0.79 kW

IModule efficiency 95.2 %Bouncer-Level áEfficiency 99.7 %System-Level

High Power

CLIC Modulator – Pulse Transformer

SM,1 D_f,1

SM,2 D_f,2

R_Load V_sek I_pri,1

I_pri,2

S_M,3 D_f,3

S_M,4 D_f,4 I_pri,3

I_pri,4

DC

AC DC

DC DC

DC

Grid

Isolation Transformer PFC

Rectifier Boost Converter (Droop Compensation)Bouncer Switching Unit Pulse Transformer Matrix transformer 2 cores / 4 primary windings

Turns ratio 62á4:(2×124)

Core material SiFe / 50 µm

High Power

CLIC Modulator – Pulse Shape/Transformer Efficiency

Core Losses 8%

Winding Losses 4%

Pulse Shape 88%

Time to flat top

Allowed droop Reverse voltage

Flat top

t

(Used pulse “energy”) Fall Time

“Dissipated” pulse “energy”

Rise + settling time 4.6 µs

Fall time <3 µs

Flat top 140 µs

Efficiency 96.7 %

(Trafo + Pulse shape)

High Power

CLIC Modulator – Higher Transformer Efficiency

0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 0.955 0.96 0.965 0.97 0.975 0.98

Efficiency (%)

Natural ester

@10kV/mm 1.5m cable

Natural ester

@10kV/mm 5m cable Mineral oil

@10kV/mm 1.5m cable

Mineral oil

@10kV/mm 5m cable

Transformer volume (m³) Mineral oil

@12kV/mm 1.5m cable

CLIC trafo

Core material SiFe 25 µm lamination Amorphous material

Insulating oil Ester 7131εr=3.2 á Mineral oilεr=2.2

Shorter load cable

Transformer design Critical damping(slightly underdamped)

Larger volume / Core splitting

Estimated efficiency ≈ ≥97.5 %

High Power

CLIC Modulator – System Efficiency

Original System

Grid Trans- former 10%

PFC 21%

Booster 24%

Switching Unit 12%

Bouncer 5%

Pulse Shape/

Transformer 28%

Improved System

Grid Trans- former

12%

PFC 15%

Booster 21%

Switching Unit 8%

Bouncer 5%

Pulse Shape/

Transformer 39%

24.8kW 13.4kW

Conventional SiC-based

DC

AC DC

DC DC

DC

Grid

Isolation Transformer PFC

Rectifier Boost Converter (Droop Compensation)Bouncer Switching Unit Pulse Transformer 98.8%

99.2%

97.5%

99.0%

97.2%

98.6%

99.4%

99.7%

98.6%

99.5%

96.7%

97.5%

93.6%

88.7%

Original Improved

High Power

SwissFEL Modulator – Pulse Efficiency @ Short Pulses

Free electron laser áX-Rays

Electron beam energy 5.8 GeV

Wavelength range 1 Å – 70 Å

Output voltage 370 kV

Output power (pulsed) 127 MW

Flat-top length 3 µs

Rise time <1 µs

Repetition rate 100 Hz

High Power

SwissFEL – Pulse Transformer

Matrix transformer 6 cores / 12 primary

Turns ratio 1:21×6á1:126

Core material SiFe / 50 µm

Rise time ≈1 µs

Fall time ≈0.9 µs

áPulse shape ≈<82 %

High Power

Solid State Modulators

2.88 MW / 3.5 ms Modulator for

European Spallation Source (ESS)

High Power

ESS Modulator Specifications

RF power

RF power RF powering cell #1

Electrical Network

Similar to RF powering cell #1

SC cavity Klystron #A

A Electrical

pulsed power Klystron modulator (Power Supply)

Klystron

B SC cavity

#B

Beam

RF powering cell #N

Pulse power 2.88 MW

Pulse voltage 115 kV

Pulse width 3.5 ms

Rise/fall time ≤150 µs

Repetition rate 14 Hz

High Power

ESS Modulator – Basic Configuration

R S

T Parallel

connection Series

connection 400 V

3-phase 50 Hz

AC DC

DC DC DC

DC DC

DC DC

DC

Energy Storage

Pulse power 2.88 MW

Pulse voltage 115 kV

Pulse width 3.5 ms

Rise/fall time ≤150 µs

Repetition rate 14 Hz

High Power

ESS Modulator – Basic Configuration

Klystron/IOT

Cf 1:n

CS

CDL1

CDL2

C_P

C_P CP

C_P LS

LDL

400 V 3-phase 50 Hz

DC AC

Grid

PFC Rectifier

SPRC-Bm1

I_O1 12.5 A

12.8 kV VO1

Vsec

Iprim

VO2

Vout

115kV 800 V

S1

SB1

SB2

S2

S4

S3

VDL2

400 V V_DL3 400 V V_DL4 400 V

VDL17

400 V VDL18

400 V

VO9

SPRC-Bm2 DC-B1

DC-B2

DC-B9

2 SPRC-Bms ISOP stack

2 SPRC-Bms ISOP stack

2 SPRC-Bms ISOP stack SPRC-Bm17

SPRC-Bm18 SPRC IPOS modulator system Balancing Circuit

SPRC-Bm3 SPRC-Bm4 VDL1

400 V

12.8kV

Pulse power 2.88 MW

Pulse voltage 115 kV

Pulse width 3.5 ms

Rise/fall time ≤150 µs

Repetition rate 14 Hz

Switching frequency 105 kHz

Modules: 2 parallel / 9 in series

High Power

ESS Modulator – Series-Parallel Resonant Converter Module

C_f 1:n

C_P

C_P C_P C_P

SPRC-Bm1

12.5 A S₁ S₂

S₄ S₃ 400 V

12.8kV C_f 1:n

C_P

C_P C_P C_P

SPRC-Bm1

12.5 A S₁ S₂

S₄ S₃ 400 V

12.8kV

C

Diodes

C_S

H-bridge: 6 x 650V MOSFETs in parallel

H-bridge 650 V MOSFETs (STY139N65M5)

Module loss distribution:

IH-bridge 221 W (179 WPCond) IRectifier diode 78 W (APT60DQ120SG) ISeries inductor 132 W (Air core with litz) ISeries capacitor 56 W (NP0 / 896 pieces) IParallel capacitor 18 W (NP0 / 864 pieces)

Σ 505 W (per module)

High Power

ESS Modulator – Step-up Transformer/Pulse Shape

Primary bobbin Primary

Secondary Secondary bobbin (POM) Primary-secondary

bobbins fastening plate

22cm

27.3cm 22cm ^-115

-115

-115 -11.5

V_out

t_rise

t₁ t₂

t2

0 0.5 1 1.5 2 2.5 3 3.5 4

Time (ms) -120

-100 -80 -60 -40 -20 0

20 Output voltage (kV) ^{-0.05 0} Time (ms)^{0.05 0.1 0.15}

-120 -100 -80 -60 -40 -20 0

3.45 3.5 3.55 3.6 3.65 3.7

Time (ms) -120

-100 -80 -60 -40 -20 0 20

K₁

K2

K₂

10 % of Vout

-113.85 = 99 % of Vout

tfall

K₁

Vout

Rising Edge Falling Edge

V_out Transformer 2:40 / Midel 7131

Losses (per module)

ICore 73.4 W (2×4×UU126/20 / N87 ferrite) IPrimary winding 12.9 W (405×0.071mm / 18 parallel) ISecondary winding 11.1 W (1125×0.071mm)

Rise time 107.8 µs (0→99%)

Fall time 83.5 µs (100→10%)

Pulse shape (total) 97.8 %

High Power

ESS Modulator – Module Loss Distribution

Cf 1:n

C_P

C_P C_P C_P

SPRC-Bm1

12.5 A S₁ S₂

S₄ S₃ 400 V

12.8kV

H-Bridge 37%

Transformer 16%

Series Inductor

21.9%

Series Capacitor

9.2%

Parallel Capacitor 2.9%

Rectifier Diodes

13.0%

Resonant converter 92.9 % (incl. transformer)

(without pulse shape)

High Power

ESS Modulator – Converter with SiC

W 50 W 100 W 150 W 200 W 250 W

H-Bridge Transformer Series Inductor Series

Capacitor Parallel Capacitor Rectifier

Diodes Si-based Converter SiC-based Converter

Klystron/IOT

Cf 1:n

CS

CP

CP

CP

CP

LS

800 V 2 x SPRC-Bm8

IPOP 2 x SPRC-Bm1

IPOP

VO1

IO1

12.5 A

12.8 kV VO1

Vsec

Iprim

VO2

Vout

115kV

800V

S1 S2

S4

S3

VO9

SPRC IPOS modulator system 800 V

12.8kV

800 V 2 x SPRC-Bm2

IPOP Improved efficiency

I1.2 kV SiC MOSFETs No balancing / Lower conduction losses

I1.7 kV SiC Diode Lower losses in rectifier

ILs⇒2×Ls@¹₂I 2×volume /¹₂losses

INew core material N97 instead of N87 áNew efficiency ≈94.4 %(+1.5% / Old: 92.9 %)

Further improvements

IMore parallel devices

IHigherfSW áShortertr/tf IHigher overrating áShortertr/tf

áNew system optimisation

High Power

ESS Modulator – System Efficiency & Loss Distribution

PFC Charging

20.3%

H-bridge 22.7%

Resonant Tank 19.3%

Transformer 10.0%

Rectifier 9.9%

Pulse Shape 17.8%

PFC Charging

11.4%

H-bridge 19.2%

Resonant Tank 17.8%

Transformer 12.1%

Rectifier 14.0%

Pulse Shape 25.4%

Si-based SiC-based

IResonant converter 92.9 % 94.4 %

IPFC charging 97.5 % 99.0 %

⇒Electrical system 90.5 % 93.5 %

IPulse shape 97.8 % 97.8 %

⇒Total efficiency 88.5 % 91.4 %

High Power

Conclusion

ρ η

η-ρ-Pareto-Front

Power Density Limit

Efficiency

Power Density Efficiency Limit

Efficiency gain(Assuming "drop-in" replacement) ICLIC Modulator ∆η=+≈4.9 % áηSiC=93.6 %

IESS Modulator ∆η=+≈2.9 % áηSiC=91.4 %

Higher Efficiency

ISwitches/diode Wide band gap devices (parallel SIC MOSFETs. . .)

ICore material SiFE 25 µm lamination or Amorphous Use of uncut cores

IInsulating oil Ester 7131εr=3.2 á Mineral oilεr=2.2

ITransformer design Critical damping(slightly underdamped) Larger volume / Core splitting

IShort load cable

IFix operating point