ISPS2014 Workshop Energy to Smart Grids Presenting results of ENIAC project: E2SG (Energy to Smart Grid)

Transcription

1 ISPS2014 Workshop Energy to Smart Grids Presenting results of ENIAC project: E2SG (Energy to Smart Grid) Bidirectional isolating AC/DC converter for coupling DC grids with the AC mains based on a modular approach Stefan Zeltner, Stefan Endres, Jens Schmenger stefan.zeltner@iisb.fraunhofer.de Fraunhofer Institute for Integrated Systems and Device Technology IISB Schottkystrasse Erlangen Germany Tel , Fax Seite 1

2 Contents Introduction Problem Effort to control complex power electronic system Proposed solution Decentralized control approach by using IPUs Implementation IPUs architecture, common mode noise immunity Results AC/DC integrated into DC Micro Grid Control System Problem AC mains EMI filter Proposed solution using smoothing transformer History of smoothing transformer Simulations and measurements Conclusions and future works Seite 2

3 Introduction PE for smart micro and nano grids Example I: High voltage grid within hybrid, plug-in or electric vehicles Example II: Future high voltage DC grid within commercial buildings s are used in smart micro or nano grids. Seite 3

4 Introduction AC/DC in future DC micro grids Example: Future DC micro grids in buildings Bidi. isolating AC/DC converter V AC DC V DC1 DC V DC2 I AC AC I 1 DC I 2 HV Battery ( V *) * using 600/650 V devices HV DC Grid (380 V) HV DC Equipment Multiport DC/DC Architecture II: I: preferred when for direct autarky usage of is renewable in focus energy I string1 I string2 V string1 V string2 PV HV DC Grid (380 V) I DC V DC HV DC Equipment HV Battery ( V) Seite 4

5 Introduction bidirectional, isolating AC/DC Topology: bidirectional bridgeless PFC + bidirectional isolating resonant DC/DC converter S 1 S 3 S 5 S 7 S 9 S 11 D 1 D 3 D 5 D 7 D 9 D 11 L1 L 1f C DC V HV EMI C f S 2 S 4 S 6 S 8 S 10 S 12 N D 2 D 4 D 6 D 8 D 10 D 12 Example for a complex PE system Seite 5

6 Problem Effort to control complex PE system x12 = 36 x3 = 9 x3 = 15 Only for the bidirectional, isolating AC/DC 66 wired connections for gate drivers, voltage, current and temperature sensors are necessary. x3 = 6 66 Seite 6

7 PCB for power switches PCB for passive components Problem Effort to control complex PE system Mechatronic integration Distributed system, Modularization Signal routing (Control signals, measurements, power supply EMI PCB for control logic PCB for gate-driver Power switches passive components Seite 7

8 Problem Effort to control complex PE system Seite 8 With state of the art centralized control approach 66 wired connections to main control unit are necessary what means: potential failures, disturbed signals, high coupling capacity.

9 Proposed solution - Decentralized control approach Seite 9 With proposed decentralized control approach: only 2 wires for Energy and data for each IPU what means: much less wiring effort, higher noise immunity, lowest possible coupling capacity.

10 Proposed solution - Decentralized control approach Based on 2-Wire-Connection Main control unit Overall system control External communication (CAN, ) Encoding control signals to datastream Booster Intelligent gate driver unit IPU Decoding of datastream Generating of gate signals Running control loops Seite 10

11 Proposed solution - Decentralized control approach Advantages of 2-Wire-Connection 2-wires, AC Power supply Easy, safe galvanic isolation by single magnetic core Several secondary sides supplying control logic, HS, Reduced requirements for high side isolation Data transfer Obtain Simplicity Seite 11

12 Proposed solution - Decentralized control approach 2-Wire-Connection: Encoding Manchester code AC DC-free UART Widely-spread microcontroller feature Applicable as transmitter (& receiver) Sync pattern Begin of data frame Synchronizing power stages Seite 12

13 Implementation IPUs architecture Novel 2-wire interface is the basis to realize easy to use, plug &play intelligent power units (IPUs) Compact IPU control electronic for four power switches in 0.04 liters Height: 15 mm IPU control Pulse capacitors Power connectors 2-wire interface Power module Seite 13 DC-link capacitors

14 Implementation IPUs architecture Main control unit 8 channels 500 kbit 16.7 khz refresh rate CAN-Interface Graphical user interface Basic Settings Voltage / Average current mode Buck, Boost, Buck-Boost Nominal values Seite 14

15 Implementation Common mode noise immunity MCU IPU Non critical transmission errors for ~ 100 kv/µs (will have no effects by failure correction mechanism) IPU Gate of power switch (IGBT) Critical No transmission errors also for > 100 kv/µs Seite 15 Excellent common mode noise immunity due to lowest possible coupling capacity and possible (no timing problems) failure correction mechanism.

16 Implementation Measurements Intelligent power unit (IPU) Test result: bridgeless totem pole PFC Test result: isolating DC/DC converter Seite 16

17 Results AC/DC integrated into DC Micro Grid Control System IPUs Seite 17 The isolating AC/DC is realized with 3 nearly identical IPUs. Battery Rack

18 Results DC Micro Grid Control System with AC/DC Seite 18

19 Results DC Micro Grid Control System with AC/DC DC Micro Grid Control System for optimized usage of renewable energy in buildings. Seite 19

20 Problem AC mains EMI filter S 1 S 3 S 5 S 7 S 9 S 11 D 1 D 3 D 5 D 7 D 9 D 11 L1 L 1f C DC V HV EMI C f S 2 S 4 S 6 S 8 S 10 S 12 N D 2 D 4 D 6 D 8 D 10 D 12 State of art totem pole bridgeless PFC Advantage of totem pole bridgeless PFC: always low impedance connection to N (PE) via S1/D1 and S2/D2. Seite 20

21 Proposed solution using smoothing transformer S 1 S 3 S 5 S 7 S 9 S 11 D 1 D 3 D 5 D 7 D 9 D 11 L1 EMI L 1f k L 2f S 2 S 4 C DC S 6 S 8 S 10 S 12 V HV N C f D 2 D 4 D 6 D 8 D 10 D 12 Bidirectional totem pole bridgeless PFC with magnetically coupled filter Benefit of the smoothing transformer: ability to integrate more than one inductance into a single magnetic structure and separation of ac and dc part of current. Seite 21

22 History of smoothing transformer Text, pictures, formulas from: David C. Hamill, Philip T. Krein: A Zero Ripple Technique Applicable To Any DC Converter, IEEE, 1999 Seite 22

23 History of smoothing transformer Benefit of the smoothing transformer: ability to integrate more than one inductance into a single magnetic structure, in this case making a fourth-order filter from three components. C 2 C db/dec Text, pictures, formulas from: David C. Hamill, Philip T. Krein: A Zero Ripple Technique Applicable To Any DC Converter, IEEE, 1999 Seite 23

24 Simulations and Measurements Network Analyzer C 3 C 2 C 1 Additional notch at 3 with winding capacitance C 3. Seite 24

25 Simulations and Measurements simple LTspice Model (with fitted parasitic elements) Problem: frequency dependence of loss mechanisms not considered. Seite 25

26 Sim. and Measurements simple LTspice Model -10dB V(l1a) dB dB dB 70-50dB -60dB -70dB -80dB -90dB Nevertheless: principal characteristics of EMIfilter (differential mode behavior) is given by simple model. simple simulation measurement dB Calculated notch: f 1 = 92 khz dB KHz 100KHz 1MHz 10MHz 100MHz Seite 26

27 Simulations and Measurements EMI Measurement Good EMI measurement results with first draft. Seite 27

28 Conclusions and future works Realizing complex power electronic systems (e.g. bidirectional, isolating AC/DC converter) with classic centralized control approach means a lot of connections between MCU and isolated power electronic devices. Problem can be solved by using a decentralized control approach based on a novel 2-wire interface with integrated power and signal transfer. Ideal implementation: intelligent power units (IPUs). Proof of concept: shown on the example of a DC Micro Grid Control System. Smoothing transformer used in a totem pole bridgeless PFC can help to save volume and can help to improve efficiency. Seite 28 Future works: realizing other complex power electronic systems with IPUs and smoothing transformer principle.

29 Thank you for your attention Fraunhofer IISB Your Partner in Power Electronics Seite 29