EMC - EV

Electromagnetic Compatibility for Electric Vehicles

Functions provided by MF-WPT system

Stand by and Wake up

The supply device is woken up by a signal from the EV.

Compatibility check

Compatibility of the primary and the secondary devices is checked with the information exchanged at the initialization phase: power classes, operating frequency, magnetic coupling, circuit topology, tuning.

Initial Alignment check

The MF-WPT system will determine that the primary and secondary devices are properly well positioned relative to each other.

Start Power Transfer

The MF-WPT system is capable to transfer the power from the primary device to the secondary device upon the request from the vehicle. The MF-WPT system does not perform power transfer until the command and control communication is properly established and the primary device and secondary device are properly positioned.

Time Scheduled Power Transfer

Perform Power Transfer

MF-WPT system transfers the power from the primary device to the secondary device in accordance with the power demand of the EV. The maximum transferring power of the off-board MF-WPT system must not be exceeded. The vehicle can change the requested transfer power.

Stop Power Transfer

MF-WPT system is able to stop transfer the power from the primary device to the secondary device in accordance with the demand of the EV. The vehicle can requested stop power transfer.

User initiated Stop Power Transfer

MF-WPT system allows the user to terminate of power supply. (e.g. pushing stop button).

Safety monitoring & diagnostics

continuous monitoring of power transfer conditions

continuous monitoring of command & control communication

continuous monitoring of safety conditions

Power Transfer Monitoring: The supply device provide means to verify that the actual output power does not differ from the expected output power by a certain limit; if the limit is exceeded, it shall stop power transfer.

Thermal Monitoring: WPT systems is capable to detect metallic objects and to stop the power transfer.

Live Object Protection: WPT systems provide life object protection by design or may provide means to detect live objects and to stop power transfer.

Failure Conditions: The supply device stops the transfer in case of of power short-circuit, earth leakage, excess temperature, insulation failure, overcurrent, overload conditions.

Ventilation: Verify that the ventilation system of the area is functioning and active.







EV Radiated Disturbance Test for Keyless Entry

This test simulates the effects of the radiated magnetic fields on a keyless entry system due to close proximity to other vehicles charging systems. The charging equipment is connected to a resistive load that represents 100 % of the load of maximum.

1. Turn on the charging equipment and allow sufficient time for stabilization.
2. Locate the loop sensor 1 m from the charging equipment face or electrical interface connector being probed. Orient the plane of the loop sensor parallel to the charging equipment faces and parallel to the axis of connectors.
3. Scan the measurement receiver over the applicable frequency range to locate the frequencies of maximum radiation, using the bandwidths and minimum measurement times according to MIL STD 461 or CISPR 16-2-3.
4. Tune the measurement receiver to one of the frequencies or band of frequencies identified in step 3 above.
5. Monitor the output of the measurement receiver while moving the loop sensor (maintaining the 1 m spacing) over the face of the EUT or around the connector. Note the point of maximum radiation for each frequency identified in step 4.
6. At the point of maximum radiation, orient the loop sensor in the vertical plane to give a maximum reading on the measurement receiver and record the reading.
7. Repeat step 4 through step 6 for at least two frequencies of maximum radiation per octave of frequencies below 200 Hz and for at least three frequencies of maximum radiation per octave above 200 Hz.
8. Repeat step 2 through step 7 for each face of the EUT and for each EUT electrical connector.

Sources: MIL STD 461 or CISPR 16-2-3

WPT System Example


1) Off-board components

2) Primary Device

3) Secondary Device

4) On-board power components

5) EV supply equipment

6) WPT vehicle power supply circuit

7) Supply equipment communication controller

8) Electric vehicle communication controller

9) Portable EV supply equipment

10) CB & RCD or RCBO

11) Plug & socket-outlet

12) RESS or traction battery

13) Electric load

a) Wireless power transfer

b) Communication according to IEC 61980-2

WPT Transfer Power Classess

Magnetic Field WPT Input Power Classes (drawn from the grid)

Class          
MF-WPT1
MF-WPT2
MF-WPT3
MF-WPT4
Power
P =< 3.7
3.7 < P =< 7.7
7.7 < P =< 22
P >

Interoperability is the state of the supply device and the EV enabling wireless power transfer via magnetic field in a safe and efficient manner. Power transfer is allowed to occur only when interoperability is established.

Interoperability Power Classes

 

 Primary Device

 

Secondary

Device

 MF-WPT

 1

 2

 3

 4

 1

 Required

 Desired

 *

 *

 2

 Desired

 Required

 *

 *

 3

 *

 *

 Required

 *

 4

 *

 *

 *

 Required

 * Under Consideration


Fundamental and Operation Frequencies for WPT Charging Stations

The Europeans expect frequency ranges 20-40 kHz, 80-90 kHz, and 119-135 kHz to be reserved for preferred accommodation of fundamental and operation frequencies for “charging stations” for electric vehicles featuring wireless power transfer (WPT). The use of these frequency bands becomes possible via the license exempt conditions granted by Decision 2013/752/EU of the European Commission on harmonization of utilization of radio frequencies for Short Range Devices.

WPT systems and car manufacturers target for these frequency bands is compliance to:

  • Conducted Emissions C1 & C2 limits at LV a.c. mains power ports of power electronic equipment with WPT functionality as specified in IEC TS 62578 Ed. 2.0 (TC 22)
  • Radiated Emissions limits (magnetic field strength at 10 m distance) specified by Decision 2013/752/EU and EN 300 330-1&2 for WPT interface of the inductive power transfer system comprising the charging station and the electric vehicle.

Abbreviations:
CENELEC: European Committee for Electrotechnical Standardization, Brussels
CD: Committee Draft; ISO, IEC
CDV: Committee Draft for Vote; IEC
CAB: Conformity Assessment Board; IEC
CASCO: Committee on Conformity Assessment; ISO
DC: Document for Comment; EC
DIN: German Institute for Standardization, Berlin
DIS: Draft International Standard; ISO
DK: German Committee
DKE: German Commission for Electrical, Electronic & Information Technologies of DIN and VDE, Frankfurt am Main
DK-IEC: German Committee of IEC
ETSI - EN 300 330-1 PART 1: TECHNICAL CHARACTERISTICS AND TEST METHODS

  • ELECTROMAGNETIC COMPATIBILITY AND RADIO SPECTRUM MATTERS (ERM); 
  • SHORT RANGE DEVICES (SRD);
  • RADIO EQUIPMENT IN THE FREQUENCY RANGE 9 KHZ TO 25 MHZ AND INDUCTIVE LOOP SYSTEMS IN THE FREQUENCY RANGE 9 KHZ TO 30 MHZ;

GA: Gemeinschaftsausschuss (Joint Committee); DIN
IEC: International Electrotechnical Commission, Geneva
IEEE: Institute of Electrical and Electronic Engineers, New York
ISO: International Organization for Standardization, Geneva
JTC: Joint Technical Committee; ISO, IEC
TC: Technical Committee; ISO, IEC, CEN, CENELEC, ETSI
TR: Technical Report; ISO, IEC, CEN, CENELEC
TS: Technical Specification; ISO, IEC, CEN, CENELEC, ETSI
VDE: Association for Electrical, Electronic & Information Technologies, Frankfurt am Main
WG: Working Group; ISO, IEC, CEN, CENELEC

2013/752/EU: Commission Implementing Decision of 11 December 2013 amending Decision 2006/771/EC on harmonisation of the radio spectrum for use by short-range devices and repealing Decision 2005/928/EC (notified under document C(2013) 8776) Text with EEA relevance

DKE / K 353 is responsible for the development of standards for the charging of electric vehicles.  These include interface descriptions and requirements for stations for the AC-charging, DC-charging, wireless charging and battery replacement.

   Working Groups:
   DKE / AK 353.0.6    EMC in the energy supply of electric vehicles
   DKE / AK 353.0.7    Battery change systems
   DKE / AK 353.0.8    User authorization for charging infrastructure
   DKE / GAK 353.0.9   Energy supply of light electric vehicles
   DKE / AK 353.0.6    EMC in the energy supply of electric vehicles
   DKE / GAK 353.0.1   Contactless charging of electric vehicles
   DKE / GAK 353.0.2   DC charging of electric vehicles
   DKE / AK 353.0.3    Communication interface from the vehicle to the power grid (V2G CI)
   DKE / GAK 353.0.4   AC charging of electric vehicles

Magnetic Field Wireless Power Transfer (MF-WPT)

MF-WPT is the wireless transfer of energy from a power source to an electrical load via a magnetic field.

Magnetic coupling
The source of a magnetic flux is a coil structure. Power transfer will be initiated by positioning two or more coil structures near each other in a way that the time varying flux generated by the primary coil structure, passes through the windings of the secondary coil structure.

Primary and secondary coil structures for WPT systems interact through an air gap. Usually a centre plane in the air gap can be defined dividing the WPT system whereas the primary coil structure is completely located on one side of this plane and the complete coil structure of the secondary device is located on the other side of the plane. For a primary device and a secondary device to be interoperable, they shall be magnetically compatible.

MF-WPT Functions

  • stand by and wake up: the supply device is woken up by the a signal from the EV.
  • compatibility check: power classes, the operating frequency, magnetic coupling, circuit topology, tuning.
  • initial alignment check: primary and secondary devices are properly well positioned relative to each other.
  • start power transfer: transfer the power from the primary device to the secondary device upon the request from the vehicle
  • time scheduled power transfer: no perform power transfer until the command and control communication is properly established and the primary device and secondary device are properly positioned.
  • perform power transfer: MF-WPT system transfer the power from the primary device to the secondary device in accordance with the power demand of the EV. The maximum transferring power of the off-board MF-WPT system shall not be exceeded. The vehicle can change the requested transfer power.
  • stop power transfer: MF-WPT system shall be able to stop transfer the power from the primary device to the secondary device in accordance with the demand of the EV. Th e vehicle can requested stop power transfer.
  • user initiated stop power transfer: allow the user to terminate of power supply. e.g. pushing stop button.
  • safety monitoring & diagnostics: command & control communication safety monitoring & diagnostics
  •    power transfer monitoring
  •    thermal monitoring
  •    live object protection
  • failure conditions: short-circuit, earth leakage, excess temperature, insulation failure, overcurrent, overload
  • continuous monitoring of power transfer conditions: the actual output power does not differ from the expected output power by a certain limit; if the limit is exceeded, it shall stop power transfer.
  • continuous monitoring of command & control communication
  • continuous monitoring of safety conditions
  • Verify that the ventilation system of the area is functioning and active

CISPR 11:2010 Raio Frequency (RF) Disturbances - IEC 61980-1 requiements

CISPR11:2010 (Ed 5.1) applies to industrial, scientific and medical (ISM) electrical equipment operating in the frequency range 0 Hz to 400 GHz. Certain frequencies are designated by the International Telecommunication Union (ITU) for unrestricted radiation from ISM equipment.

AC Power Port    - CISPR 11; Conducted disturbances (150kHz-30MHz)
Table 6 (Class A) - Mains terminal disturbance voltage limits for class A group 2 equipment measured on a test site


Table 7 (Class B) - Mains terminal disturbance voltage limits for class B group 2 equipment measured on a test site

WPT System and Enclosure Port  - CISPR 11; 
 Table 12 - Limits of the magnetic field strength for induction cooking appliances intended for commercial use

WPT System Port   - CISPR 11; 
 Table 6 (Class A) - Mains terminal disturbance voltage limits for class A group 2 equipment measured on a test site
 Table 7 (Class B) - Mains terminal disturbance voltage limits for class B group 2 equipment measured on a test site

Power Transfer to Moving Vehicles

Currently the WPT transfer distance is in range of several centimeters. Among the technical challenges to overcome we can mention:

  • acceptable power transfer efficiency at high transfer range
  • increasing power level
  • misalignment tolerance
  • safety considerations




Coil-to-coil distance & 30 m working wavelength transfer efficiencies


2-turn copper ribbon coil (3cm wide, 0.14 mm thick) with d=60cm and 5 to 70 pF adjustable high voltage capacitor. The quality factor of the resonator is 1338 in the absence of the metallic plane and 1329 in the presence of a metallic plane.

Source: Safe Wireless Power Transfer to Moving Vehicles: Design of Radiationless Antenna