Device for inductive transmission of electrical energy from a primary circuit to a secondary circuit and method for operating such a device

Abstract

Device for the inductive transmission of electrical energy with a primary circuit (1) and a secondary circuit (2) which is connected via a rectifier (3) to the positive pole and the negative pole of an energy storage device (6) to be charged by the electrical energy, wherein, for communication between the secondary circuit (2) and the primary circuit (1), a controllable switching means (T1) short-circuiting the secondary circuit (2) and a measuring device (7) associated with the primary circuit (1) are provided for detecting the change in the transmitted electrical energy due to the actuation of the switching means (T1), wherein the rectifier (3) is a full-bridge rectifier formed with diodes (D1, D2, D3, D4), and the controllable switching means (T1) is connected in parallel to one of the diodes (D3) of the full-bridge rectifier (3) connected to the negative pole of the energy store (6), wherein the associated measuring device (7) is a measuring coil arrangement by means of which the magnetic field between the primary and secondary circuits is measured.

Description

[0001] The invention relates to a device for the inductive transmission of electrical energy with a primary circuit and a secondary circuit which is connected via a rectifier to the positive pole and the negative pole of an energy storage device to be charged by the electrical energy, wherein a controllable switching means which short-circuits the secondary circuit and a measuring device assigned to the primary circuit for detecting the change in the transmitted electrical energy due to the actuation of the switching means are provided for communication between the secondary circuit and the primary circuit.

[0002] Such a device is known from DE 20 2010 016 586 U1. According to DE 20 2010 016 586 U1, the vehicle comprises a secondary regulator for adjusting a secondary power drawn from the secondary inductance, wherein the secondary regulator contains a switching device by means of which the drawn secondary power can be changed in steps. The stationary unit comprises a primary regulator for adjusting the primary power that can be fed into the primary inductance. The primary regulator comprises a first measuring device by means of which an electrical operating parameter of the power supply device influenced by the secondary power can be measured. The primary regulator adjusts the feedable primary power depending on changes in the operating parameter measured by the first measuring device.The switching means is arranged between the two supply lines, optionally between the terminals of the secondary circuit, or before or after a converter, so that the connection between the secondary circuit and the battery to be charged is completely short-circuited when the switching means is actuated for communication.

[0003] DE 10 2014 220 224 A1 discloses a method for contactless charging of a battery-operated object via a magnetically coupled coil pair, which comprises a primary coil arrangement of a charging station and a secondary coil arrangement of the battery-operated object. An inverter is supplied via an intermediate circuit voltage generated by a first rectifier and excites the primary coil arrangement, and an alternating voltage is provided between two connection points at the secondary coil arrangement. Furthermore, it is provided that the connection points are connected to one another for a predetermined time interval during each half-cycle of the alternating voltage, and the intermediate circuit voltage is regulated such that switching points of the inverter are in the region of a zero crossing of a current of the primary coil arrangement, so that the inverter is controlled in a soft-switching manner.

[0004] DE 101 58 794 B4 discloses an inductive contactless power transformer having a primary side comprising a first primary-side inductance and an oscillator for generating an alternating signal that is supplied to the primary-side inductance, and having a secondary side comprising a secondary-side inductance that can be coupled to the primary-side inductance, a time-variable load, and a detection device for determining a secondary-side power requirement of the load, wherein the first oscillator is a voltage-controlled oscillator whose frequency can be adjusted depending on the power requirement determined by the detection device.

[0005] DE 100 56 611 A1 discloses a magnetic field setting for at least one winding generating a magnetic field, which is connected to a controllable / regulatable energy supply device, with a comparator for determining deviations between a setpoint value and an actual value of the magnetic field strength, as well as with a reference sensor for specifying an electrical variable determining the magnetic field strength of the generated magnetic field and controllable for the control / regulation device of the energy supply device, wherein the comparator specifies the signal of the reference sensor according to the currently determined setpoint / actual value deviation.

[0006] DE 10 2014 220 265 A1 discloses a method for operating an inductive charging device for a vehicle, wherein the vehicle has at least one secondary coil in the vehicle underbody, wherein at least one magnetic field sensor for measuring a magnetic field of the inductive charging device is arranged on an outer vehicle line or between the outer vehicle line and the secondary coil, wherein in a first method step the charging power of the inductive charging device is throttled if the magnetic field of the inductive charging device measured with the magnetic field sensor exceeds a predetermined limit value.

[0007] The object of the invention is to provide alternative devices and a method for operating such devices.

[0008] The object is achieved by a device according to the independent claims 1 and 2 and a method according to claim 6. Advantageous further developments are specified in the subclaims.

[0009] Accordingly, a device for the inductive transmission of electrical energy comprises a primary circuit and a secondary circuit, which is connected via a rectifier to the positive and negative poles of an energy storage device to be charged with the electrical energy. For communication between the secondary circuit and the primary circuit, a controllable switching means short-circuiting the secondary circuit and a measuring device associated with the primary circuit for detecting the change in the transmitted electrical energy due to the actuation of the switching means are provided. According to the invention, the rectifier is a full-bridge rectifier formed with diodes, and the controllable switching means is connected in parallel with one of the diodes of the full-bridge rectifier connected to the negative pole of the energy storage device.

[0010] As a result, when the switching device is actuated - i.e. closed - the secondary circuit is only short-circuited in every second half-wave of the energy-transmitting signal.

[0011] In an alternative embodiment of the invention, the controllable switching means is designed as a changeover switch and is either in a position in which the secondary circuit is short-circuited directly or in a position in which the secondary circuit is short-circuited via a resistor.

[0012] The associated measuring device is a measuring coil arrangement through which the magnetic field between the primary and secondary circuits is measured.

[0013] This advantageously allows existing devices to detect changes in the physical quantities that are essential in these devices. A (partial) short circuit in the secondary circuit, for example, changes both the current and / or voltage in the primary circuit and the resulting magnetic field. This can then be detected by the measuring coil arrangement, which also serves to detect magnetic field changes due to foreign objects.

[0014] In an advantageous embodiment, the measuring coil arrangement can be an arrangement of planar coils on a carrier.

[0015] This makes production simple and therefore cost-effective.

[0016] In one embodiment of the invention, the controllable switching means is formed with a MOSFET.

[0017] In a further advantageous embodiment of the invention, the primary and secondary circuits are resonant circuits. This allows for greater efficiency in the magnetic coupling of the two circuits.

[0018] In a method according to the invention for operating such a device according to the invention, information is transmitted from the secondary circuit to the primary circuit by alternately switching the switching means on and off and is detected there by the measuring device.

[0019] The invention will be described in more detail below using an exemplary embodiment with the aid of figures. Fig. 1 a schematic representation of a device according to the invention, Fig. 2 the effect of a closed switching device in the secondary circuit on the signal shape of the charging current in the primary circuit. Fig. 3 a schematic representation of an alternative device according to the invention with a changeover switch, and Fig. 4 a schematic partial representation of an alternative device according to the invention with a measuring coil arrangement.

[0020] The Fig. Figure 1 shows a schematic representation of the parts of a device for the inductive transmission of energy, for example, to charge a vehicle battery 6 from the general power grid. For this purpose, an alternating voltage signal is provided via energy converters (not shown) and is transmitted to a Fig. 1. This is formed by a primary coil L1 and a first capacitor C1 connected in series therewith, wherein the inductance of the primary coil L1 and the capacitance of the capacitor C1 are tuned such that the primary circuit 1 resonates with the secondary circuit 2, which is also formed by a secondary coil L2 and a second capacitor C2, at the frequency of the alternating voltage signal at the input of the primary circuit 1.

[0021] The alternating signal then present at the output of the secondary circuit 2 is rectified by means of a full-bridge rectifier 3 and, if necessary, applied to an energy storage device, for example a vehicle battery 6, via further voltage converters.

[0022] The full-bridge rectifier 3 is formed by four diodes, D1 to D4, with a transistor T1 connected in parallel to the third diode D3 in order to be able to short-circuit them when the first transistor T1 is activated.

[0023] In the same way, the first transistor T1 could be connected in parallel with the fourth diode D4 instead of the third diode D3, since this transistor is then also connected between one of the terminals 4, 5 of the secondary circuit 2 and the negative pole of the battery 6.

[0024] In the illustrated embodiment of the Fig. 1, in the event that a positive potential is applied to terminal 4 of the secondary circuit 2 and a negative potential is applied to terminal 5 of the secondary circuit 2, the secondary circuit 2 would be short-circuited via the first transistor T1 and the fourth diode D4, whereby the primary circuit 1 would supply a higher energy for this time, which, as in Fig. 2, in an increase of the charging current 10.

[0025] This charging current 10 can be as in the Fig. 1 is detected by means of a measuring device 7, wherein the device according to the invention can communicate from the secondary circuit 2 to the primary circuit 1 without the need for an additional communication path.

[0026] In Fig. Figure 3 also shows the primary circuit 1 and the secondary circuit 2 of a device according to the invention. However, in this exemplary embodiment, a changeover switch WS is connected in parallel with the secondary circuit 2. In a first position, this switch short-circuits the secondary circuit 2 directly and, in a second position, via a resistor R. This also influences the current flow through the primary circuit and thus also the magnetic field. By determining one or both of the two variables on the primary side, information can be transmitted from the secondary side to the primary side, thus enabling communication.

[0027] The Fig.4 shows an alternative embodiment of a device according to the invention with a measuring coil arrangement MSA, which here is formed with a number of planar individual coils, which are formed, for example, on a film or other carrier. Using this measuring coil arrangement MSA, the magnetic field generated by the primary coil of the primary circuit 1 and influenced by a (partial) short circuit in the secondary circuit 2 can be measured. The measured values ​​can be compared with predetermined values ​​in an evaluation device (not shown), and the information pulses generated by the (partial) short circuit in the secondary circuit can be determined therefrom, whereby communication can take place between the secondary circuit 2 and the primary circuit 1.

Claims

[1] Device for the inductive transmission of electrical energy with a primary circuit (1) and a secondary circuit (2) which is connected via a rectifier (3) to the positive pole and the negative pole of an energy storage device (6) to be charged by the electrical energy, wherein, for communication between the secondary circuit (2) and the primary circuit (1), a controllable switching means (T1) short-circuiting the secondary circuit (2) and a measuring device (7) associated with the primary circuit (1) are provided for detecting the change in the transmitted electrical energy due to the actuation of the switching means (T1), wherein the rectifier (3) is a full-bridge rectifier formed with diodes (D1, D2, D3, D4), and the controllable switching means (T1) is connected in parallel to one of the diodes (D3) of the full-bridge rectifier (3) connected to the negative pole of the energy store (6), wherein the associated measuring device (7) is a measuring coil arrangement by means of which the magnetic field between the primary and secondary circuits is measured. [2] Device for the inductive transmission of electrical energy with a primary circuit (1) and a secondary circuit (2) which is connected via a rectifier (3) to the positive pole and the negative pole of an energy storage device (6) to be charged by the electrical energy, wherein, for communication between the secondary circuit (2) and the primary circuit (1), a controllable switching means (T1) short-circuiting the secondary circuit (2) and a measuring device (7) associated with the primary circuit (1) are provided for detecting the change in the transmitted electrical energy due to the actuation of the switching means (T1), wherein the controllable switching means (T1) is designed as a changeover switch and is either in a position in which the secondary circuit is directly short-circuited or in a position in which the secondary circuit is short-circuited via a resistor (R), wherein the associated measuring device (7) is a measuring coil arrangement by means of which the magnetic field between the primary and the secondary circuit is measured. [3] Device according to claim 1 or 2, characterized by that the measuring coil arrangement is an arrangement of planar coils on a carrier. [4] Device according to one of the preceding claims, characterized by that the controllable switching means (T1) is a MOSFET. [5] Device according to one of the preceding claims, characterized by that the primary circuit (1) and the secondary circuit (2) are resonant circuits. [6] Method for operating a device according to one of claims 1 to 5, in which information is transmitted from the secondary circuit (2) to the primary circuit (1) by alternately switching the switching means (T1) on and off.

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