Arrangement for contactless inductive transmission of electrical power

• US 6,005,304 A
• Filed: 06/24/1997
• Issued: 12/21/1999
• Est. Priority Date: 12/24/1994
• Status: Expired due to Fees

• Current Assignee: Daimler-Benz AG (Mercedes-Benz Group AG)
• Original Assignee: Daimler-Benz AG (Mercedes-Benz Group AG)
• Inventors: Seelig, Anton
• Primary Examiner(s): Paladini, Albert W.
• Application Number:
  US08/860,413
• Time in Patent Office: 910 Days
• Field of Search: 307/104, 307/17, 340/310.07, 336/DIG. 2, 336/178
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: Y10S 336/02 Separable

Abstract

A device for the contactless inductive transmission of electric energy to a movable consumer has a stationary primary circuit designed as an arrangement of elongated parallel leads connected to a source of high frequency alternating voltage or current and a transmission head arranged on the movable consumer. The transmission head consists of a ferrite core and of a secondary winding that surrounds the ferrite core and is magnetically coupled to the primary circuit. The primary circuit lead arrangement has an outer lead designed as an almost closed housing (7) and a middle lead (6) arranged approximately at the center of the housing. The current (11) that flows in the outer lead has the same intensity but an opposite flow direction to the current in the middle lead. The middle lead (6) is surrounded by a U-shaped ferrite core (2) that carries the secondary winding (W₂). In order to transmit electric energy independently and at the same time to several movable consumers, a constant medium frequency current (J₁) flows through the transmission device. The current is kept constant in that the transmission arrangement is connected in parallel to a capacitor (C_E) connected in series to an inductor (L_E) and to a medium frequency voltage source (MFG1). A resonance is created between the inductor (L_E) and the capacitor (C_E) at the frequency (fo) of the medium frequency voltage source (MFG1).

Claims

1. Arrangement for contactless transmission of electrical power to a movable consumer, having a dormant primary circuit configured as an elongated, parallel arrangement of conductors, the circuit being connected to a high-frequency AC voltage or alternating current source, the arrangement further having a transmitter head that is attached to the movable consumer and comprises a ferrite core and a secondary winding surrounding this ferrite core and magnetically coupled to the primary circuit, wherein the conductor arrangement of the primary circuit has an outside conductor configured as a nearly-closed housing and a center conductor located approximately in the center of the housing, with a current flowing in the outside conductor that is of equal magnitude and directed in the opposite direction of the current flowing in the center conductor, and that the center conductor is surrounded by a U-shaped ferrite core that supports the secondary winding.

2. Arrangement according to claim 1, wherein the U-shaped ferrite core supports on both legs windings located opposite the primary-side conductor and whose height approximately corresponds to the height (H) of the primary conductor and is between 0.3 and 0.5 times the total height (H_G) of the U-shaped core.

3. Arrangement according to claim 1 wherein the height (H) of the primary conductor is selected in relation to the passage width (b_k) of the magnetic flux adjacent to the conductor region such that maximum power is transmitted.

4. Arrangement according to claim 1 wherein the outside walls of the housing that lie opposite the center conductor are arched to provide the most uniform possible distribution of the current over the widest possible current-guidance region (b_I, b.sub.γ

).

5. Arrangement according claim 1 wherein the cross sections of the outside and center conductors and the passage width (b) of the magnetic flux are geometrically shaped, and the size ratios are dimensioned, such that the electrical power loss is minimal.

6. Arrangement according to claim 1 characterized in that the secondary winding is switched in series with a capacitor, which compensates the inductive voltage drop at the scatter inductance of the transmitter head.

7. Arrangement according to claim 1 wherein the length of the path and primary conductor arrangement is greater than 100 m.

8. Arrangement according to claim 1 wherein a plurality of capacitors are switched in series with the center conductor for compensating the inductive voltage drop, and are distributed over the entire length of the center conductor such that the compensation is effected in numerous segments with partial voltages that can be controlled with technology.

9. Arrangement according to claim 1 further comprising a the center web (S) has has near the base a ferritic region of approximately the width (b_K) for reducing the magnetic gap width to an absolutely necessary mechanical air gap (δ

₁, δ

₂).

10. Arrangement according to claim 9, further comprising a capacitor that supplies the magnetization current for generating the magnetic flux density in the air gap of the ferrite core, the capacitor being switched to the secondary winding in parallel to the load resistor.

11. Method of simultaneous, contactless transmission and individually-settable power to a plurality of moved consumers having an arrangement according to claim 1, wherein the transmitter arrangements are fed by a middle-frequency current source with a constant current that is independent of the voltages of the consumers, and electronic control members correspondingly establish the consumer voltages of the transmitted power on the moved consumers.

12. Method according to claim 11, wherein the impression of a constant current into one of the transmitter arrangements is effected by means of a middle-frequency voltage source via a resonance circuit comprising an inductance and a capacity, with the inductance and capacity being dimensioned such that they are in resonance at the frequency fo of the middle-frequency voltage source, and the relationship ##EQU2## exists between the voltage of the source and the impressed current, and that the transmitter arrangement is connected in parallel to the capacity, which is switched in series with the inductance and the voltage source.

13. Method according to claim 11, wherein the current impressed into the load impedance of a consumer is supplied to an electronic control member that rectifies the current via a bridge rectifier and filters it through a storage inductance, and supplies the direct current formed in this way alternatingly, via a diode, to a capacity charged to a DC voltage at a high clock frequency, or conducts it past the capacity via an electronic switch in its conducting phase, with a regulating device changing the relative blocking phase of a clock period of the electronic switch such that the required DC voltage is supplied to the DC voltage consumers VB connected to the capacity with a fluctuating current consumption.

14. Arrangement according to claim 1 wherein the center conductor is connected, at the end of the path traversed by a movable consumer, to the outside conductor, that is, the housing, and a middle-frequency generator feeds in the current between the center conductor and the housing at the beginning of the path.

15. Arrangement according to claim 1 wherein the primary circuit forms a closed, endless track extending in an arbitrary manner, the track permitting gap-free energy transmission to a plurality of movable consumers, and that, at the connections of the primary circuit, a network conducts the feeder current supplied by the middle-frequency generator into the center conductor and the outside conductor in opposite directions.

16. Arrangement according to claim 15 wherein the network (8) is provided at a plurality of locations on the endless track for balancing the current feed-in.

17. Arrangement according to claim 15, wherein for coupling currents (I₁, I₁ '"'"') of equal magnitude and in opposite directions into the center conductor and the outside conductor of a closed track, the network includes a transformer having two secondary windings whose center ends, which form a voltage center point, are connected to one another by way of the connections of the coaxial outside conductor, and their outside inputs, which are in antiphase, are connected to the center conductor by way of the connections.

18. Arrangement according to claim 17 wherein the supply line pairs respectively connected to the inside and outside conductors of one or both ends of the primary-side conductor arrangement are guided by way of compensation throttles, which effect the uniformity of the currents in the center and outside conductors.

19. Arrangement according to claim 18, wherein the supply lines to the outside-conductor connections are guided to a common connecting point before the guide-through through the compensation throttles on the sides of the compensation throttles facing away from the outside-conductor throttles, with the common connecting point optionally being potential-free, that is, insulated, or connected to the center tap of the middle-frequency source and/or the mass or ground potential.

20. Arrangement according to claim 18 wherein the center conductor comprises a plurality of windings, and the uniformity of the total currents in the center conductor and the current in the outside conductor in that the winding number ratio of the compensation throttles coincides with the winding number of the center conductor.