Method and arrangement for automatic contactless charging

• US 5,654,621 A
• Filed: 08/16/1995
• Issued: 08/05/1997
• Est. Priority Date: 10/28/1992
• Status: Expired due to Fees

• Current Assignee: Daimler-Benz Antiengesellschaft
• Original Assignee: Daimler-Benz AG (Mercedes-Benz Group AG)
• Inventors: Seelig, Anton
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US08/424,371
• Time in Patent Office: 720 Days
• Field of Search: 320/2, 320/21, 320/28, 320/54, 901/17, 364/483, 364/550, 336/DIG. 2
• US Class Current: 320/108
• CPC Class Codes: B60L 53/11 DC charging controlled by the charging station, e.g. mode 4
• CPC Class Codes: B60L 53/126 Methods for pairing a vehicle and a charging station, e.g. establishing a one-to-one relation between a wireless power transmitter and a wireless power receiver
• CPC Class Codes: B60L 53/38 specially adapted for charging by inductive energy transfer
• CPC Class Codes: B60R 16/03 for supply of electrical power to vehicle subsystems or for circuit arrangements for charging batteries H02J7/00
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 2310/46 for ICE-powered road vehicles
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

In a process for contactless energy transmission in charging the battery of a vehicle, in particular an electric car, by means of an inductive transmitter having a primary element (1) and a secondary element (2) which is attached to the vehicle, the secondary element (2) is made freely accessible and the primary element is power driven to move in all three spatial coordinates within a predetermined spatial area. In this process the primary element (1) and the secondary element (2) are placed, under sensor control, in predetermined positions relative to each other and then electrical energy is transmitted in the medium frequency range by means of the inductive transmitter.

Claims

1. A method of contactless energy transmission during charging of a battery of a vehicle using an inductive transmission arrangement which includes:

a primary inductive element and a secondary inductive element, the secondary inductive element being disposed on the vehicle, the primary inductive element being movable with respect to the vehicle, the primary inductive element for moving into an approach position with respect to the secondary inductive element to achieve magnetic coupling with the secondary inductive element, and

a charging device having an inverter for supplying the primary inductive element with a current having a frequency greater than about 20 kHz, the charging device additionally having a demodulation apparatus, and coupling detection circuitry which includes a peak rectifier, an analog-digital converter, a memory controlled by a clock generator, and a comparison stage,

wherein capacitors are provided which resonate with the inductance of the primary inductive element and the inductance of the secondary inductive element, there being an a gap on the order of centimeters between the primary and secondary inductive elements,

wherein a battery state detection and charging current control means is provided in the vehicle,

wherein a means of contactless transmission of information from the vehicle to the charging device is provided in the vehicle, the means for contactless transmission of information including a high frequency generator disposed in the vehicle for producing a high frequency signal, and a modulating apparatus configured as a frequency modulator for producing a modulated high frequency signal,

wherein an orientation signal emitter is provided on the vehicle to supply an orientation signal,

wherein there is a charging current setter associated with the inverter of the charging device, and

wherein there is at least one electronic switch associated with the inventer, the method comprising;

(a) measuring a battery charging current and determining a deviation of the measured battery charging current from a predetermined desired charging current value, with the battery state detection and charging current control means;

(b) transmitting the determined charging current deviation, under control of the means for contactless transmission of information, to the charging current setter associated with the inverter of the charging device, step (b) including

(b-1) modulating the high frequency signal with a charging current deviation signal produced by the battery state detection and charging control means, using the modulating apparatus,

(b-2) transmitting the modulated high frequency signal produced in step (b-1) through an electromagnetic field to the demodulation apparatus of the charging device,

(b-3) using the demodulation apparatus to regenerate the charging current deviation signal, and

(b-4) supplying the regenerated charging current deviation signal to the inverter;

(c) controlling switching time or switching frequency of the at least one electronic switch of the inverter supplying the current to the primary inductive element, so that the charging current deviation becomes zero; and

(d) before steps (a) through (c) are conducted, finding a favorable approach position and magnetic coupling between the movable primary inductive element and the secondary inductive element disposed on the vehicle, step (d) including

(d-1) supplying an orientation signal from the orientation signal emitter provided on the vehicle to the modulation apparatus,

(d-2) modulating the high frequency signal with the orientation signal as the primary inductive element approaches the secondary inductive element, and

(d-3) transmitting the modulated signal produced in step (d-2) from the vehicle to the charging device,

(d-4) demodulating the signal transmitted in step (d-3), and

(d-4) using the coupling detection circuitry to indicate whether an amplitude of the orientation signal, and, therefore, coupling between the primary inductive element and the secondary inductive element disposed on the vehicle, increases, decreases, or remains the same.

2. A method as defined in claim 1, wherein, the movable primary inductive element is attached to a moveable arm and moved by drive motors in three spatial coordinates to approach the secondary inductive element,

wherein the secondary inductive element is positioned, with the vehicle, in a spatial region reachable by the primary inductive element attached to the moveable arm,

wherein, as a function of output signals of the comparison stage, the drive motors which move the movable arm are set in operation and halted by drive guide and coupling means, the drive guide and coupling means implementing conventional drive control and regulating functions,

wherein the demodulator identifies the orientation signal emitted from the vehicle and supplies it to the drive guide and coupling means, and

wherein the drive guide and coupling means halts all of the drive motors and emits a signal indicating coupling has been achieved when an evaluation of the output signals of the comparison stage indicates no increase in the amplitude of the received orientation signal.

3. A method as defined in claim 2, wherein the signal indicating coupling has been achieved causes a keyed signal emitter to switch the inverter on and off in a rhythmical fashion,

wherein the signal indicating coupling has been achieved is transmitted to the vehicle and regenerated by a keyed signal demodulator, switches off the orientation signal, and switches on a charging initiation signal for a predetermined pulse time duration,

wherein the charging initiation signal is switched off by the modulation apparatus after termination of the predetermined pulse time duration, and the charging current deviation signal is connected to the modulation apparatus, and

wherein the charging initiation signal demodulated and received by the charging device connects a current guide input of the inverter to the charging current deviation signal subsequently emitted by the demodulator.

4. A method as defined in claim 2, further comprising:

automatically returning the primary inductive element to a resting position after a charging process has ended,

wherein a charging end signal transmitted by the vehicle resets a charging operation memory for switching off the inverter by means of a current reference variable changeover switch for switching a current reference value input from the modulator to the current reference variable switched on prior to the charging process,

wherein the charging end signal is also supplied to the drive guide and coupling means, and triggers a backward movement of the drive motors,

wherein end switches halt the drive motors in a resting position of the movable arm with the primary inductive element, and cause the drive guide and coupling means to emit a start release signal,

wherein the start release signal is supplied to a keyed signal generator means for switching the inverter on and off in a rhythmical manner,

wherein the start release signal is received at the vehicle and regenerated by a keyed signal demodulator, resets a charging end signal generator, and brings a start signal generator into a vehicle ready to start state.

5. A method of contactless energy transmission during charging of a battery of a vehicle using an inductive transmission arrangement which includes:

a primary inductive element and a secondary inductive element, the secondary inductive element being disposed on the vehicle, the primary inductive element being movable with respect to the vehicle, the primary inductive element for moving into an approach position with respect to the secondary inductive element to achieve magnetic coupling with the secondary inductive element, and

a charging device having an inverter for supplying the primary inductive element with a current having a frequency greater than about 20 kHz,

wherein capacitors are provided which resonate with the inductance of the primary inductive element and the inductance of the secondary inductive element, there being a gap on the order of centimeters between the primary and secondary inductive elements,

wherein a battery state detection and charging current control means is provided in the vehicle,

wherein a means for contactless transmission of information is provided on the vehicle, the means for contactless transmission of information including a high frequency generator, a modulating apparatus, and a charging current deviation indicator,

wherein there is a charging current setter associated with the inverter of the charging device, and

wherein there is at least one electronic switch associated with the inventer,

the method comprising;

(a) measuring a battery charging current and determining a deviation of the measured battery charging current from a predetermined desired charging current value, with the battery state detection and charging current control means, the battery state detection and charging current control means including a battery state detection means a charging current controller, and a measurement controller;

step (a) including

(a-1) transmitting a desired value for a charging current from the battery state detection means to the charging current controller,

(a-2) obtaining a measuring signal with the aid of the measurement converter, the measuring signal being proportional to the current induced in the secondary inductive element, and

(a-3) supplying the measuring signal to the charging current controller, the charging current controller forming a charging current deviation signal from the desired value for a charging current and the measuring signal;

(b) transmitting the determined charging current deviation, under control of the means for contactless transmission of information, to the charging current setter associated with the inverter of the charging device, step (b) including

(b-1) supplying the charging current deviation signal to the charging current deviation indicator, and

(b-2) using the charge current deviation indicator to connect the charging current deviation signal to the modulating apparatus, which in turn modulates a high frequency signal generated by the high frequency generator;

(c) controlling switching time or switching frequency of the at least one electronic switch of the inverter supplying the current to the primary inductive element, so that the charging current deviation becomes zero; and

(d) when the battery is charged, emitting a signal from the battery state detection means to indicate the battery is charged, the signal emitted by the battery state detection means switching the charging current deviation signal off at the modulating apparatus by resetting the charging current deviation indicator, and producing a charging end signal for transmission to the charging device and to the modulating apparatus to turn off the modulating apparatus.

6. A method as defined in claim 5, wherein the means for contactless transmission of information from the vehicle to the charging device includes a high frequency generator disposed on the vehicle for producing a high frequency signal, and a modulation apparatus configured as a frequency modulator for modulating the charging current deviation, thereby producing a modulated high frequency signal,

wherein the modulated high frequency signal is transmitted through an electromagnetic field to a demodulation apparatus at the charging device,

wherein the demodulation apparatus regenerates the signal for the charging current deviation in the charging device, and

wherein the regenerated signal is supplied to the inverter that produces the high frequency current.

7. An apparatus for contactless energy transmission, comprising:

a primary inductive element and a secondary inductive element, the secondary inductive element being disposed on a vehicle, the primary inductive element being movable with respect to the vehicle to a position at which the primary inductive element is spaced apart from the secondary inductive element to form a transformer with a gap,

a charging device having a capacitor which is connected in series with the primary inductive element and having an inverter for supplying the primary inductive element with an oscillating current via the capacitor, the inverter having an inverter frequency greater than about 20 kHz,

another capacitor carried by the vehicle, the another capacitor being connected in parallel to the secondary inductive element, the capacitors having capacitances which are selected so that the capacitors resonate with the transformer with a gap at around the inverter frequency; and

means for adjusting the amplitude of oscillation of the oscillating current by changing the inverter frequency,

wherein the diameter or outer dimensions of the primary inductive element and the secondary inductive element are approximately ten to twenty times the gap width which remains between the two transmission elements when they form the transformer with a gap.

8. An apparatus as defined in claim 7, further comprising means for detecting a charging current deviation, wherein the secondary inductive element disposed on the vehicle serves as a transmission element for contactless transmission of a high frequency signal for transmitting the charging current deviation from the vehicle to the charging device.

9. An apparatus as defined in claim 8, wherein the primary inductive element serves as a transmission element of the charging apparatus which receives the high-frequency signal containing the charging current deviation.

10. An apparatus as defined in claim 7, wherein the primary inductive element and the secondary inductive element have a shell or disk shape, and wherein a winding height is small relative to the diameter or outer dimensions of the elements.

11. An apparatus as defined in claim 7, wherein the gap between the primary and secondary inductive elements, when they form the transformer with a gap, lies in a plane, and wherein the primary inductive element is positioned on one side of this plane and the secondary inductive element is positioned on the other side.

12. A method according to claim 11, wherein the step of adjusting the amplitude of the oscillating current comprises:

measuring a battery charging current and determining a deviation of the measured battery charging current from a predetermined desired charging current value, with a battery state detection and charging current control means provided in the vehicle;

transmitting the determined charging current deviation, under control of a means for contactless transmission of information provided in the vehicle, to a charging current setter associated with the inverter of the charging device; and

controlling a switching frequency of at least one electronic switch provided in the inverter so that the charging current deviation becomes zero.

13. A method as defined in claim 12, wherein the means for contactless transmission of information from the vehicle to the charging device includes a high frequency generator disposed on the vehicle for producing a high frequency signal, and a modulation apparatus configured as a frequency modulator for producing a modulated high frequency signal,

wherein the modulated high frequency signal is transmitted through an electromagnetic field to a demodulation apparatus at the charging device,

wherein the demodulation apparatus regenerates the signal for the charging current deviation in the charging device, and

wherein the regenerated signal is supplied to the inverter.

14. A method as defined in claim 12, wherein a battery state detection means is disposed on the vehicle and transmits a desired value for a charging current to a charging current controller,

wherein a measuring signal, obtained with the aid of a measurement converter and proportional to the current transmitted to the primary inductive element, is additionally supplied to the charging current controller,

wherein the charging current controller forms a charging current deviation signal from the desired value for a charging current and the measuring signal, and supplies the charging current deviation signal to a charging current deviation indicator which connects the charging current deviation signal to the modulating apparatus, which in turn modulates the high frequency generator, and

wherein, when the battery is charged, the battery state detection means emits a signal indicating the battery is charged which switches the charging current deviation signal off at the modulating apparatus by resetting the charging current deviation indicator, and produces a charging end signal for transmission to the charging device and to the modulating apparatus to turn off the modulating apparatus.

15. A method as defined in claim 13, wherein the step of moving the primary inductive element comprises:

emitting an orientation signal from an orientation signal emitter provided on the vehicle, and supplying the orientation signal to the modulation apparatus to produce an orientation-modulated high frequency signal as the primary inductive element approaches the secondary inductive element, and transmitting the orientation-modulated high frequency signal from the vehicle to the charging device,

wherein the charging device further includes coupling detection circuitry, including;

a peak rectifier,

an analog-digital converter,

a memory controlled by a clock generator, and

a comparison stage, and

wherein signals from the coupling detection circuitry indicate whether an amplitude of the orientation signal, and, therefore, coupling between the primary inductive element and the secondary inductive element disposed on the vehicle, increases, decreases, or remains the same.

16. A method as defined in claim 15, wherein the movable primary inductive element is attached to a moveable arm and moved by drive motors in three spatial coordinates to approach the secondary inductive element,

wherein the secondary inductive element is positioned, with the vehicle, in a spatial region reachable by the primary inductive element attached to the moveable arm,

wherein, as a function of output signals of the comparison stage, the drive motors which move the movable arm are set in operation and halted by drive guide and coupling means, the drive guide and coupling means implementing conventional drive control and regulating functions,

wherein the demodulator identifies the orientation signal emitted from the vehicle and supplies it to the drive guide and coupling means, and

wherein the drive guide and coupling means halts all of the drive motors and emits a signal indicating coupling has been achieved when an evaluation of the output signals of the comparison stage indicates no increase in the amplitude of the received orientation signal.

17. A method as defined in claim 16, wherein the signal indicating coupling has been achieved causes a keyed signal emitter to switch the inverter on and off in a rhythmical fashion,

wherein the signal indicating coupling has been achieved is transmitted to the vehicle and regenerated by a keyed signal demodulator, switches off the orientation signal, and switches on a charging initiation signal for a predetermined pulse time duration,

wherein the charging initiation signal is switched off by the modulation apparatus after termination of the predetermined pulse time duration, and the charging current deviation signal is connected to the modulation apparatus, and

wherein the charging initiation signal demodulated and received by the charging device connects a current guide input of the inverter to the charging current deviation signal subsequently emitted by the demodulator.

18. A method as defined in claim 16, further comprising:

automatically returning the primary inductive element to a resting position after a charging process has ended,

wherein a charging end signal transmitted by the vehicle resets a charging operation memory for switching off the inverter by means of a current reference variable changeover switch for switching a current reference value input from the modulator to the current reference variable switched on prior to the charging process,

wherein the charging end signal is also supplied to the drive guide and coupling means, and triggers a backward movement of the drive motors,

wherein end switches halt the drive motors in a resting position of the movable arm with the primary inductive element, and cause the drive guide and coupling means to emit a start release signal,

wherein the start release signal is supplied to a keyed signal generator means for switching the inverter on and off in a rhythmical manner, and

wherein the start release signal is received at the vehicle and regenerated by a keyed signal demodulator, resets a charging end signal generator, and brings a start signal generator into a vehicle ready to start state.

19. A method of contactless energy transmission during charging of a battery of a vehicle using an inductive transmission arrangement, the inductive transmission arrangement including

a primary and a secondary inductive element, the secondary inductive element being disposed on the vehicle, the primary inductive element being movable with respect to the vehicle to a position adjacent the secondary inductive element to achieve magnetic coupling with the secondary inductive element,

plastic material on the primary and secondary inductive elements for electrical insulation and protection, the plastic material on each of the inductive elements having a respective thickness,

a charging device having a capacitor which is connected in series with the primary inductive element and having an inverter for supplying an oscillating current to the primary inductive element via the capacitor, the inverter having an inverter frequency which is greater than about 20 kHz, and

another capacitor carried by the vehicle, the another capacitor being connected in parallel to the secondary inductive element,

wherein said method comprises the steps of:

moving the primary inductive element toward the secondary inductive element to a position at which the primary inductive element is spaced apart from the secondary inductive element to form a transformer with a gap, the gap between the primary and secondary inductive elements being at least as large as the sum of the thickness of the plastic material on the primary inductive element and the thickness of the plastic material on the secondary inductive element, the capacitors having capacitances which are selected so that the capacitors resonate with the transformer with a gap at around the inverter frequency; and

adjusting the amplitude of oscillation of the oscillating current by changing the inverter frequency.

20. A method as defined in claim 19, wherein the diameter or outer dimensions of the primary inductive element and the secondary inductive element are approximately ten to twenty times the gap width which remains between the two transmission elements when they form the transformer with a gap, this gap width being up to the order of centimeters.

21. A method as defined in claim 20, further comprising means for detecting a charging current deviation with a detecting means in the vehicle, and using a modulated high frequency signal for transmitting the charging current deviation from the vehicle via the secondary inductive element to the charging device.

22. A method as defined in claim 21, wherein the primary inductive element receives the modulated high-frequency signal containing the charging current deviation.

23. A method as defined in claim 20, wherein the primary inductive element and the secondary inductive element have a shell or disk shape, and wherein a winding height is small relative to the diameter or outer dimensions of the elements.

24. A method as defined in claim 19, wherein the step of moving the primary inductive element is conducted by moving the primary inductive element along three spatial coordinates.