Inductive Power Transfer: The Capacitive Problem!

Transcription

1 Inductive Power Transfer: The Capacitive Problem! Paolo GUGLIELMI POLITECNICO DI TORINO - DENERG paolo.guglielmi@polito.it HEV TCP 26, Versailles, Apr. 2017

2 Agenda The Dynamic WPT The Goal and the Challenge The Susa Test Site POLITO and SAET Solutions The DWPT configuration adopted The precision problem The embedding problem First Tests Small prototypes At the test site POLITO vs SAET embedding solution Conclusions: Lesson learned

3 Dynamic Wireless Power Transfer 85kHz Compensation AC/DC On-board converter Load Receiver Transmitter DC/AC converter AC/DC converter Electrical network Compensation Transfer electric energy to a vehicle in motion at high speed Motorway operation oriented

4 Dynamic Wireless Power Transfer DWPT Highway Contact up-roof Highway Strongly reduced Visual impact Long distances and pads Different possible users Large power demand NEW power distribution problem

5 Dynamic Wireless Power Transfer MV 10-22kV 3phase 50Hz Trasfo MV-LV Y- Y Configuration #1 for Motorway Small on pole Sub-station 600kVA AC/DC 12pulse ICTComm CSCU Sign. Power Supply V DC local distribution 500m

6 Dynamic Wireless Power Transfer MV 6.5kV DC Configuration #2 for Motorway Insulated DC/DC bidirectional Small underground sub station 500kW ICTComm CSCU Sign. Power Supply V DC local distribution 500m

7 The GOAL and the Challenges 1. An interoperable test site DWPT capability up to 100m & 100kW total each coil designed to operate between 0 and 20kW Flexibility each coil can individually limit the transmittable power Two different distribution and WPT configuration on ground POLITO and SAET solutions The vehicle will chose how much power to take MINIMAL COST 2. All ICT and communication issues Authorization Accounting and Metering 3. EMF for human exposure

8 Agenda The Dynamic WPT The Goal and the Challenge The Susa Test Site POLITO and SAET Solutions The DWPT configuration adopted The precision problem The embedding problem First Tests Small prototypes At the test site POLITO vs SAET embedding solution Conclusions: Lesson learned

9 The Susa test-site TEST SITE The Italian test site by Susa, Piedmont - ITALY

10 The Susa test-site BRUXELLES TEST SITE TURIN The Italian test site by Susa, Piedmont - ITALY

11 The Susa test-site TEST SITE TURIN The Italian test site by Susa, Piedmont - ITALY

12 The Susa test-site A32 MOTORWAY TEST SITE SUSA MUNICIPALITIES The Italian test site by Susa, Piedmont - ITALY

13 The Susa test-site The Italian test site by Susa, Piedmont - ITALY

14 POLITO power configuration 400V AC 400V AC Trasfo 120kVA Shelter side the road ICTComm CSCU Sign. Power Supply 650Vdc AC/DC SC 22kW DC out Power room To SAET solution Road 650Vdc DC/HFs Coils + Cap. 25 x 2m (x 2) = 100m

15 SAET power configuration Shelter side the road 400V AC 400V AC Trasfo Trasfo. Y- Y 120kVA 100kVA AC/DC 12puls ICTComm CSCU Sign. Power Supply Power room To POLITO solution Road 650Vdc DC/HFs Coils + Cap. 25 x 2m (x 2) = 100m

16 SAET and POLITO TX & RX solution SIMPLE magnetic solution Same physical dimensions meaning similar coupling factors Same RECEIVER will be adopted but different solutions will be implemented on the transmitting side In both NO ferrite on ground No shielding on ground

17 SAET and POLITO RX solution Designed to cope with EMF ICNIRP 2010 guidelines

18 SAET and POLITO transmitting solutions Same physical dimensions meaning same Ampere-Turns Transformer-less Transformer-based Embedded Caps Separated Caps Multi-turn Single-turn Very High Voltage Lower Voltage Low currents High currents 40Arms 400Arms 1.5 x 0.5 m 4 cm down the level of the road

19 Power electronic transmitters Status: 2nd version: final boards, all pieces ready Devel.: Ended Scope: Fully validated in lab; to be validated on site SAET Peculiarity Same communication protocol for CAN interfacing RS485 for synchronization Reduced cost IP68 solution 1200V SiC based H-bridge

20 Agenda The Dynamic WPT The Goal and the Challenge The Susa Test Site POLITO and SAET Solutions The DWPT configuration adopted The precision problem The embedding problem First Tests Small prototypes At the test site POLITO vs SAET embedding solution Conclusions: Lesson learned

21 Transmitting Capacitors: the choice Among the different topologies we chose for the series-series compensation possible

22 Transmitting Capacitors: the choice Decrease of the VA rating of the power electronics Possibility to adopt soft-switching techniques Strong reduction of commutation losses Increase of the power transfer capability

23 Transmitting Capacitors: the sizing SAME VA RATING as THE RELATED INDUCTOR POLITO on L1 = 280uH and 12.5nF 5400Vrms SAET on L1 = 4uH and 875nF 1000Vrms Smaller Bigger Embeddable Maintainable Precise Less precise Very High Voltage High Voltage Easy cooling Difficult cooling Patented Commercial

24 Transmitting Capacitors: POLITO High voltage test Dedicate Connectors Thermal test 20% Load Mounting solution

25 IDEAL COUPLING PRIMARY AND SECONDARY CURRENTS VS Coupling factor Capacitors: PRECISION WHY? Transmitter current amplitude versus frequency Receiver current amplitude versus frequency Transmitter current phase versus frequency

26 Capacitors: PRECISION WHY? Current peaks for frequencies close to ω0 Transmitter current amplitude versus frequency Receiver current amplitude versus frequency Sharp variations of the equivalent behavior for frequencies close to ω0 Transmitter current phase versus frequency

27 Capacitors: PRECISION WHY? -10% -5% -1% +1% +5% +10% Variation of C1 Variation of C2

28 Capacitors: PRECISION WHY? Experimental on demo Transmitter current amplitude Transmitter current phase

29 Transmitting Capacitors: PRECISION WHY? It is impossible to assure the switching operations at pure resonant conditions (resistive behavior) The phase can change dependently on the coupling, the load or the tolerances on the components Transmitter current amplitude Transmitter current phase

30 TX and RX Capacitors: PRECISION WHY? The supplying power electronics has to be able to manage slight hard-switching The power electronics has to be able to manage capacitive commutations Operations at variable frequency needs for an over-rating of the power switches or a fast and robust control on the receiver side Transmitter current amplitude Transmitter current phase

31 TX and RX Capacitors: PRECISION how much? The proposed HW realization for POLITO let obtain a precision better than 1% on a single component Anyway a tuning or a selection is needed Adopting the parallel more smaller components let we reach higher statistic level of precision

32 Inductors PRECISION can be good POLITO solution Manufactured and tested before embedding

33 Agenda The Dynamic WPT The Goal and the Challenge The Susa Test Site POLITO and SAET Solutions The DWPT configuration adopted The precision problem The embedding problem First Tests Small prototypes At the test site POLITO vs SAET embedding solution Conclusions: Lesson learned

34 Coils Embedding POLITO solution First embedding trial

35 Coils Embedding first measurement HIOKI LCR HiTESTER Test conditions: Test voltage 5 V Test frequency 85 khz Measured coil parameters in laboratory conditions (before embedding) L = μh R = 303 mω Measured embedded coil parameters L = μh R = 17.2 Ω

36 Coils Embedding Hypothesis Hypothesis on the source of the unexpected behavior Capacitive coupling between the coil and the concrete

37 Coils Embedding capacitive coupling Hypothesis verification Coil of reduced dimension: 30x40 cm2 6 turns Replicated embedding conditions in laboratory

38 Coils Embedding capacitive coupling Hypothesis verification Parallel resonance appears Phase Ampl. Before embedding After embedding

39 Coils Embedding capacitive coupling Hypothesis verification Main concept Coil s copper Wire insulation Concrete Coil s copper Wire insulation Bitumen Additional layer of bituminous coating Concrete

40 Coils Embedding capacitive coupling Hypothesis verification Parallel resonance Disappears Phase Ampl. Before embedding After embedding with Bitumen

41 Coils Embedding capacitive coupling ON SITE Different resins have been tested OK KO!! OK Different - Resin HF - Resin Pre Bitumen Or in hole

42 Coils Embedding than a SOLUTION (!??!) OK OK OK BUT NOT SO EASY OK

43 Coils Embedding than a SOLUTION (!??!) MAPEI Mapegrount Cold asphalt

44 Coils embedding: and the SAET solution No problem with ground coupling whichever material is used WHY? Much lower inductance Coil itself need to be protected by a cover for simple handling Lower copper area exposition

45 Coils embedding: and the SAET solution BUT The INDUCTANCE value DEPENDS on the physical placement of the cable into ground The connection to the manhole strongly influence the inductance values. Different solution to the problem can anyway be foreseen

46 Agenda The Dynamic WPT The Goal and the Challenge The Susa Test Site POLITO and SAET Solutions The DWPT configuration adopted The precision problem The embedding problem First Tests Small prototypes At the test site POLITO vs SAET embedding solution Conclusions: Lesson learned

47 Lesson Learned 1. The capacitive problem is hard and need to be addressed at the DESIGN level In the transmitting and receiving resonators it is fundamental IT CAN STRONGLY LIMIT THE OUTPUT POWER IT LEAD TO UNPREDICTABLE CAPACITIVE AND INDUCTIVE COMMUTATION The main solution is PRECISION AND TUNING IN THE RESONATORS BETTER THAN 0.5% IN THE RESONANCE FREQUENCY In the embedding process materials vs solutions is the main issue. PHYSICAL COIL dimensions and ADOPTED MATERIALS for embedding can transform you inductor in resistor!

48 Thank you! Paolo GUGLIELMI Associate Professor, Politecnico di Torino DENERG Italy