Inductive charging device, system for inductive energy transmission, and method for generating drive control current

Abstract

The present invention provides an inductive charging device, a system for inductive energy transmission, and a method for generating a drive control current, particularly for a transmitting coil of an alignment device. [Solution] An inductive charging device 110 comprising a first energy coil 111, an alignment device 112, and a drive control device 113 for generating a drive control current for driving and controlling at least one transmitting coil of the alignment device, wherein the drive control device 113 generates a drive control signal by receiving or generating an AC signal having a carrier frequency, pulse shapes and amplitude modulates the AC signal by multiplying it with a pulse signal to generate an amplitude modulated AC signal, and filters the amplitude modulated AC signal to attenuate harmonics.

Description

Technical Field

[0001] The present invention relates to an inductive charging device, a system for inductive energy transmission, and in particular a method for generating a drive control current for a transmitting coil of an alignment device.

[0002] An inductive charging device for charging a vehicle is described in the SAE J 2954:2024-08-13 standard. As a standardized alignment system, this standard (Chapter 12; Appendices C and D) proposes a so-called differential inductive positioning system (DIPS). This system has an alignment device (also referred to as an alignment transmitter) on the transmitting side, and this alignment device is preferably arranged in a stationary first inductive charging device (also referred to as a ground unit or ground assembly or GA (Ground Assembly)) arranged in or on the ground. According to the standard, this alignment device on the transmitting side has five transmitting coils, and each of these transmitting coils generates one alignment magnetic field as an alternating magnetic field with a different frequency. Therefore, each transmitting coil is driven by an alternating current, and each alternating current has a unique carrier frequency.

[0003] On the receiving side, an alignment device (also referred to as an alignment receiver) is provided, and this alignment device is preferably arranged in a mobile second inductive charging device (also referred to as a vehicle unit or vehicle assembly or VA (vehicle assembly)) arranged in or on the bottom of the vehicle. According to the standard, this alignment device on the receiving side has two receiving coils, and these receiving coils detect alignment magnetic fields generated by the transmitting coils and distinguishable based on different frequencies. Then, from this alignment magnetic field, the relative alignment of the inductive charging devices with each other, and ultimately the alignment of the vehicle relative to the inductive charging device on the ground side can be determined.

[0004] In alternative embodiments of the inductive charging device, a different number of transmitting and / or receiving coils may be used. Essentially, it is sufficient, for example, for the transmitting alignment device to have at least one transmitting coil and the receiving alignment device to have at least one receiving coil.

[0005] Such charging devices or parts thereof are also known from German Patent Publication No. 102022203489, German Patent Publication No. 102022120691, and German Patent Publication No. 102022107568.

[0006] The fundamental problem underlying this invention is to optimize the drive control of at least one transmitting coil, particularly with respect to the distortion of the generated magnetic field, EMC characteristics, and system stability.

[0007] According to one aspect of the present invention, -In the energy transmission operation, a first energy coil generates an alternating magnetic field for inductively transmitting energy to a second energy coil of a second inductive charging device, - An alignment device comprising at least one transmitting coil for generating an alignment magnetic field for mutually identifying the relative alignment of energy coils in alignment operation, - An inductive charging device comprising a drive control device for generating a drive control current for driving and controlling at least one transmitting coil, wherein the drive control device is -Receives or generates an AC signal having a carrier frequency, -To generate an amplitude-modulated AC signal, the AC signal is pulse-shaped by multiplication with a pulse signal, - An inductive charging device is provided, configured to generate a drive control current by filtering out harmonics of an amplitude-modulated AC signal.

[0008] According to another aspect of the present invention, a system for inductive energy transmission is provided, comprising an inductive charging device according to any one of claims 1 to 11, and another inductive charging device for mounting on and / or inside a vehicle, in particular a mobile inductive charging device, the other inductive charging device is -In the energy transmission operation, a second energy coil is used to receive energy inductively transmitted from the first energy coil, - The alignment device includes at least one receiving coil for detecting the alignment magnetic field and for mutually identifying the relative alignment of the energy coils during the alignment operation.

[0009] According to another aspect of the present invention, a method for generating a drive control current for driving and controlling at least one transmitting coil of an alignment device of an inductive charging device, wherein the inductive charging device comprises a first energy coil for generating an alternating magnetic field for inductively transmitting energy to a second energy coil of a second inductive charging device in an energy transmission operation, and an alignment device having at least one transmitting coil for generating an alignment magnetic field for mutually identifying the relative alignment of the energy coils in an alignment operation. -Receives or generates an AC signal having a carrier frequency, -To generate an amplitude-modulated AC signal, the AC signal is pulse-shaped by multiplication with a pulse signal, A method is provided for generating a drive control current by filtering out harmonics of an amplitude-modulated AC signal to attenuate them.

[0010] Preferred embodiments of the present invention are provided in the dependent claims. It is obvious that the claimed methods and systems have similar and / or identical preferred embodiments, such as the claimed inductive charging device, which are provided in the dependent claims and disclosed in the present invention.

[0011] The underlying idea of ​​this invention is to process a signal superimposed and modulated onto a carrier signal (AC signal) by pulse shaping and filtering so that switching on and off is not performed by sharp edges. To this end, the AC signal is multiplied, in particular, by a pulse signal, for example, a preset or (e.g., generated in a microcontroller) raised cosine signal, so that the overall signal (drive control current) is given a desired pulse shape by the carrier signal that has a "smoother" progression rather than sharp edges, thereby reducing or completely avoiding distortion and harmonics. Thus, pulse shaping is performed by multiplying the carrier signal and the pulse signal (which may also be called the modulated signal). This multiplication corresponds to amplitude modulation. This ultimately allows for influence on the spectrum of the transmitted signal (i.e., the alignment magnetic field) emitted from the transmitting coil through the selection of the pulse signal waveform. If the pulse signal is rectangular (the simplest case), for example, it may become impossible or only difficult to comply with certain criteria (OBW, transmit bandwidth boundary, etc.). Selecting an appropriate pulse signal, such as a raised cosine signal, makes it possible to comply with these criteria.

[0012] Accordingly, the present invention proposes a control and drive concept for the transmitting coil of a aligning device of an inductive charging device on the transmitting side, which can be used, for example, for the GA transmitting coil of a DIPS in GA as described in the SAE standard mentioned at the beginning. In the proposed solution, a carrier current ("AC signal") (e.g., sinusoidal) with minimal distortion and a high amplitude modulation degree of freedom is supplied to the transmitting coil. Thus, the magnetic field generated by the transmitting coil driven by this can meet stringent EMC requirements and improve system stability.

[0013] In the solution according to the present invention, the AC signal in the transmitting coil is a carrier wave, the transmitting coil frequency is the carrier wave frequency of the transmitting coil, and the carrier wave is filtered by filtering. Therefore, amplitude modulation in the form of pulse shaping and filtering work together to generate a drive control current for driving and controlling at least one transmitting coil. Preferably, a separate drive control current is generated for each transmitting coil.

[0014] In one preferred embodiment, the drive control device is configured to generate a pulse-width modulated signal as an AC signal. This is an easily manageable option for the carrier wave.

[0015] Preferably, the drive control device is further configured to perform low-pass or band-pass filtering of the amplitude-modulated AC signal. This allows for the removal or at least attenuation of undesirable harmonics.

[0016] The drive control device may also be configured to set the effective value of the current by setting the duty cycle and phase of the AC signal, and / or to amplitude modulate it. By setting the phase and duty cycle, compliance can also be achieved, for example, by compensating for tolerances of the components.

[0017] The drive control device may further be configured to pulse-shape the amplitude-modulated AC signal using pulse shaping filters, particularly raised cosine filters, root-raised cosine filters, sink filters, and Gaussian filters. The pulse signal used in this process, multiplied with the AC signal, produces a desired smoothed transition instead of sharp edges.

[0018] In another embodiment, the drive control device is configured to amplify or attenuate the amplitude-modulated and filtered AC signal. This allows the amplitude of the AC signal to be brought to a desired intensity.

[0019] In one embodiment, the drive control unit is further configured to power amplify the amplitude-modulated and filtered AC signal. This power amplification is available when the current capacity of another component of the drive control unit is insufficient for the required current strength of the drive control current for the transmitting coil.

[0020] The drive control system can be implemented, for example, by a processor, a controller (e.g., a microcontroller), or another common component. Alternatively, the drive control system can be implemented by separate components, such as a signal generation unit, a filter unit, and an amplification unit, each implemented by a dedicated hardware component, processor, or controller.

[0021] One configuration is further specified to include an overcurrent protection circuit and / or overvoltage protection circuit on the output side. This is used to protect components of the drive control system, for example, in the event that an overvoltage is induced during energy transmission to the transmitting coil.

[0022] In principle, a single transmitting coil is indeed sufficient for alignment. However, preferably, the alignment device has multiple transmitting coils, particularly four or five, to generate one alignment magnetic field each as an alternating magnetic field, each having a different carrier frequency. In this case, the drive control device is configured to generate a different drive control current for each of the transmitting coils.

[0023] The inductive charging device according to the present invention is preferably a stationary inductive charging device in the sense of the above-mentioned standard for installation on and / or in the ground, for example, a GA.

[0024] It is self-evident that the features listed above and further described below can be used not only in the indicated combinations but also in other combinations or individually without departing from the scope of the present invention.

[0025] Embodiments of the present invention are shown in the following drawings and will be described in detail in the following description. The same reference numerals refer to the same or similar components that are functionally the same.

Brief Description of the Drawings

[0026] [Figure 1] It is a diagram of a vehicle equipped with an inductive charging device according to the present invention, significantly simplified. [Figure 2] It is a plan view of an inductive charging device according to the present invention equipped with a short-distance alignment transmitter and a long-distance alignment device. [Figure 3] It is a diagram showing an inductive charging device equipped with an alignment receiving device for a vehicle charging system according to the present invention. [Figure 4] It is a block diagram of one embodiment of a system according to the present invention for inductive energy transmission. [Figure 5A] It is a graph for explaining the requirement for modulation width. [Figure 5B] It is another graph for explaining the requirement for modulation width. [Figure 6A] It is a graph for explaining the spectrum of a carrier signal having distortion. [Figure 6B] It is a graph for explaining the spectrum of a carrier signal without distortion. [Figure 7] It is a graph for explaining the phase angle. [Figure 8] It is a graph of an FFT simulation example for three different signal shapes. [Figure 9]This is a block diagram of one embodiment of the drive control device according to the present invention. [Figure 10] This is a graph of an example output signal for generating a desired AC signal. [Figure 11] This is a graph of the pulse signal as the output of a pulse shaping filter. [Figure 12] This is a graph of an amplitude-modulated AC signal. [Figure 13] This is a block diagram of one exemplary embodiment of the signal processing stage of a drive control device according to the present invention. [Figure 14] This is a graph of the binary data stream being transmitted. [Figure 15] This is a graph of the envelope generated by a pulse shaping filter. [Figure 16] This is a graph of an amplitude-modulated AC signal.

[0027] Figure 1 shows an exemplary mobile inductive charging device 1a, which is located on a vehicle 2 equipped with an energy storage device 3 and is positioned above a stationary inductive charging device 1b. During operation, energy can be transferred from the stationary inductive charging device 1b to the mobile inductive charging device 1a, thereby charging the energy storage device of the vehicle 3.

[0028] The mobile inductive charging device 1a and the stationary inductive charging device 1b together form a part of the vehicle charging system 8, or they are a part of the vehicle charging system 8. Basically, it is also possible to operate the vehicle charging system 8 bidirectionally. In this case, energy can be temporarily transmitted from the mobile inductive charging device 1a to the stationary inductive charging device 1b. The stationary inductive charging device 1b, which is placed in the ground 35 in Figure 1, may instead be embedded in the roadway (not shown here). In the embedded configuration, the inductive charging device 1b may be covered by a specific layer of the roadway, or it may be terminated flush with the roadway surface. The mobile inductive charging device 1a is, for example, located inside or attached to the bottom of the vehicle 2. The two inductive charging devices 1a and 1b each have one energy transmission winding (energy coil) and preferably a plurality of flow guide elements.

[0029] Figure 2 shows a plan view of one embodiment of the inductive charging device 1b. In this embodiment, the inductive charging device 1b has a positioning device (also referred to as a positioning transmitter) comprising a short-range positioning transmitter NAH-POS and a long-range positioning transmitter FERN-POS. In this embodiment, the short-range positioning transmitter NAH-POS is implemented in the form of four short-range transmitting windings 13 (transmitting coils) configured as flat coils, but may be implemented with more or fewer transmitting windings. The long-range positioning transmitter FERN-POS is implemented in this embodiment as a solenoid (positioning signal winding), but can basically be omitted. The long-range positioning transmitter FERN-POS transmits a long-range positioning signal FERN-SIG in the form of an alternating magnetic field (also referred to as a long-range positioning magnetic field) during the positioning process. The near-range alignment transmitter (NAH-POS) transmits multiple near-range alignment signals (NAH-SIG) in the form of alternating magnetic fields (also called near-range alignment magnetic fields) during the alignment process. These near-range alignment signals (NAH-SIG) differ from each other, for example, by frequency, and are different from the far-range alignment signal (FERN-SIG). Furthermore, an energy transmission winding 4b (energy coil), preferably configured as a flat coil, and a flow guide element 5b, for example, in the form of a ferrite plate, are provided.

[0030] Figure 3 shows a mobile inductive charging device 1a having an alignment device (also referred to as an alignment receiver) equipped with two sensor windings 9a1 and 9a2 (receiving coils), although it is also possible to use basically just one or more sensor windings. In this embodiment, eight flow guide elements 5a are shown, which are arranged radially in one plane around the center 7 of the energy transmission winding 4a. However, these may be more or fewer flow guide elements. The energy transmission winding 4a, preferably configured as a flat coil and covered by the flow guide elements 5a in the plan view, is shown by a dashed line. The sensor windings 9a1 and 9a2 are formed here as solenoids (also referred to as cylindrical coils).

[0031] In this embodiment, the first sensor winding 9a1 is arranged axially symmetrically with respect to the second sensor winding 9a2 with respect to the vehicle longitudinal direction 6. The first sensor winding 9a1 and the second sensor winding 9a2 intersect at least approximately at the center 7 of the energy transmission coil 4a. The first sensor winding 9a1 has a first radial longitudinal direction 11a1, and the second sensor winding 9a2 has a second radial longitudinal direction 11a2. The angle between the first radial longitudinal direction 11a1 and the vehicle longitudinal direction 6 is at least approximately the same as the angle between the second radial longitudinal direction 11a2 and the vehicle longitudinal direction 6, although these angles may be of different magnitudes. Thus, the sensor windings 9a1 and 9a2 form a cross-shaped arrangement.

[0032] During the charging process, vehicle 2 is positioned above stationary inductive charging device 1b, and energy is transmitted to inductive charging device 1a. Here, the flow guide element assumes the function of flow guiding. In the charging state, magnetic field lines of the magnetic field extend approximately radially through the flow guide element. The first radial longitudinal direction 11a1 and the second radial longitudinal direction 11a2 are similarly oriented radially and, consequently, at least substantially parallel to the magnetic field lines. Therefore, only a relatively small voltage is induced, or no voltage is induced at all, in the first sensor winding 9a1 and the second sensor winding 9a2. This is advantageous because otherwise, if the energy transmission output is large and consequently the magnetic flux density is high, the sensor windings could easily be damaged. Therefore, no additional costs are required to prevent damage to the device.

[0033] The inductive charging devices 1b and 1a according to the present invention may be part of the vehicle charging system 8 according to the present invention. In this case, one alignment receiver can receive signals from both the short-range alignment transmitter NAR-POS and the long-range alignment transmitter FERN-POS. This is advantageous because one alignment receiver can provide two different alignment methods that function optimally in two different distance ranges. For further details on the basic structure and function of the inductive charging devices 1a and 1b, please refer to the literature mentioned at the beginning. These documents are explicitly referenced here.

[0034] Figure 4 shows a block diagram of one embodiment of a system 100 according to the present invention for inductive energy transmission, comprising a first (preferably stationary) inductive charging device 110 and a second (preferably mobile) inductive charging device 120. The first inductive charging device 110 may be basically configured as the charging device 1b shown in Figure 2. The second inductive charging device 120 may be basically configured similarly to the charging device 1a shown in Figure 3.

[0035] The first inductive charging device 110 includes a first energy coil 111 for generating an alternating magnetic field for inductively transferring energy to a second energy coil 121 of the second inductive charging device 120 during energy transfer operation. The first inductive charging device 110 further includes a alignment device 112 comprising at least one transmitting coil for generating an alignment magnetic field for identifying the relative alignment of the energy coils 111, 121 during alignment operation, and a drive control device 113 for generating a drive control current to drive and control the at least one transmitting coil. The second inductive charging device 120 includes a second energy coil 121 for receiving energy inductively transferred from the first energy coil 111 during energy transfer operation, and a alignment device 122 comprising at least one receiving coil for detecting the alignment magnetic field and identifying the relative alignment of the energy coils 111, 121 during alignment operation. The alignment devices 112 and 122 may be configured in the same way as the DIPS described in the SAE standard or the literature cited therein, or they may be configured differently.

[0036] For example, a positioning device 112 used in DIPS is considered a wireless system in the frequency range of 9 kHz to 30 MHz, and therefore strict criteria are applied to it. From Table 1, the most important of these criteria can be seen in rows 1 to 3. The criterion in row 4 is another additional criterion that is closely related to criterion 3.

[0037] [Table 1]

[0038] Criterion 1: This criterion means that 99% of the energy of the modulated transmitted signal must be within the transmission bandwidth boundary. Criterion 2: This criterion specifies the requirements for the modulation bandwidth, which are concretely shown based on the graph in Figure 5. Figure 5A shows a graph illustrating the modulation bandwidth requirements for carrier frequencies below 135 kHz. Figure 5B shows a graph illustrating the modulation bandwidth requirements for carrier frequencies above 135 kHz. This implies a high requirement for the signal shape, as the modulation bandwidth should be within the transmission bandwidth or within ±7.5% of the carrier frequency. The stricter of the two options should be used. Criterion 3: This criterion indicates that there are limits to electromagnetic interference in the 9kHz-30MHz and 30MHz-1GHz ranges that must be complied with. Criterion 4: This criterion represents a problem caused by the change in inductance of the transmitting coil due to the introduction of a different ferrite material into the system. This is applicable when the GA operates with a VA that has a different ferrite arrangement configuration. This criterion is used to ensure interoperability.

[0039] According to the present invention, a correspondingly designed drive control circuit 113 is provided so that the alignment device 112 simultaneously satisfies the four judgment criteria described above.

[0040] Table 2 below shows how well the judgment criteria applied to the alignment device are observed for various possible drive control systems, particularly combinations of control stages and signal processing. From this table, it can be seen that, for amplitude modulation, all judgment criteria can only be reliably observed by combining a distortion-free carrier signal with intentionally selected pulse shaping.

[0041] [Table 2]

[0042] Therefore, without pulse shaping, it is impossible to meet criteria 1 and 2 at an appropriate transmission frequency (e.g., pre-set for DIPS in the SAE standard). This is because the spectrum shown in Figure 6A is relatively broadband, and much of the energy extends into the sidebands. This also negatively affects criterion 3. The spectrum shown in Figure 6B shows the combination of "undistorted carrier + pulse shaping". Here, we can clearly see some less important sidebands, but these are not very high in energy. Therefore, this combination makes it possible to satisfy criteria 1 and 2 well.

[0043] Another requirement for the transmit current is that, in order to minimize the influence of ferrite materials, such as VA, on the amplitude of the transmit current, this transmit current should have as inductive a phase angle as possible (criterion 4). The reason for this is shown in the graph in Figure 7, which specifically illustrates the selection of a large phase angle for the transmit coil circuit.

[0044] Curve 200 shows the coil current level in dB against frequency. The reactive power compensation for the transmitting coil is designed here exemplarily for a resonant frequency of 100 kHz. Curve 201 shows a possible case where the inductance of the transmitting coil is increased by introducing another ferrite material. As a result, the resonant frequency drops to approximately 40 kHz with the same design of reactive power compensation. If the system operates at a resonant state at the original inductance of the transmitting coil (operating point 202), then a new operating point 203 will be reached when the inductance of the transmitting coil is increased. This will result in a significant decrease in the transmitting current, which is undesirable. The goal is for the effects of the introduced other ferrite material (e.g., operation of a system with a VA from a different manufacturer) to remain broadly unaffected in order to ensure interoperability. This can be achieved by a large inductive phase angle between the transmitting coil current and its excitation voltage. This case is shown at operating point 204. What can be seen here is that the effect of the change in the inductance of the transmitting coil due to the additional ferrite material has a significantly smaller impact on the coil current than at operating points 202 and 202 (operating point 205).

[0045] For example, when a Class D amplifier is used, its carrier wave shape is strongly distorted when the inductive phase angle is large, and it no longer resembles a sine wave, but rather a triangular wave signal. Therefore, if the drive control of the transmitting coil is not properly designed, it is difficult to satisfy criteria 3 and 4.

[0046] Figure 8 shows graphs of FFT simulation examples for three different signal shapes with an exemplary frequency of 100 kHz and amplitude of 5 V over a relatively wide frequency range. These graphs specifically illustrate the possible EMC radiation problems for three signal shapes with different edge steepness (curve 210: rectangular signal, curve 211: triangular wave signal, curve 212: sine wave signal). These simulation examples are noisy, but still demonstrate the relationship. From the time-domain simulation results of these signals, it can be seen that the rectangular signal 210 can radiate significantly higher amplitudes than the triangular wave signal 211 (distorted carrier) or the sine wave signal 212 (undistorted carrier) in the frequency range above 1 MHz. The envelope of the triangular wave signal drops at 40 dB / decade below the lower cutoff frequency, while the envelope of the rectangular signal drops at only 20 dB / decade. An ideal sine wave signal would radiate only at its fundamental frequency, in this case 100 kHz. This simulation includes errors and noise, and therefore the sinusoidal signal is not ideal. We can also see the frequency spectrum here, but this frequency spectrum drops to high frequencies the fastest of all three signal shapes. This clearly shows that, from an EMC perspective, a sinusoidal signal shape is more advantageous than triangular and rectangular signal shapes whenever possible.

[0047] Furthermore, in the case of triangular wave signals, calibrating the transmitted current is difficult and extremely time-consuming. The RMS of the fundamental current must be set to a specific value, which can cause significant scattering in triangular waves with similar settings. Consequently, variations between different systems can become excessively large. This can be a major drawback, especially in mass production.

[0048] In the "distortion-free carrier wave + pulse shaping" combination, the PWM signal, which may be generated by a microcontroller (μC), for example, is not used directly but must be processed accordingly. Therefore, the coil current always has a sinusoidal signal shape regardless of its phase angle (criterion 4). Signal processing can be performed, for example, by a low-pass filter stage or a band-pass filter stage. Thus, in this combination, criteria 3 and 4 are not mutually exclusive, and both can be satisfied simultaneously.

[0049] Figure 9 shows a block diagram of a first embodiment of the drive control device 113 according to the present invention, which is preferably usable in a stationary inductive charging device (1b in Figures 1 and 2, 110 in Figure 4). The drive control device 113 is configured to generate a drive control current for driving and controlling at least one transmitting coil (13, 41 in Figure 2). According to the present invention, the drive control device 113 is configured to generate a drive control current by receiving or generating an AC signal having a carrier frequency, pulse-shape the AC signal to generate an amplitude-modulated AC signal by multiplication with a pulse signal, and filter to attenuate harmonics of the amplitude-modulated AC signal. In the embodiment shown in Figure 9, the proposed circuit concept for the drive control device 113 includes, for example, a control stage 130, a filter / amplifier stage 131, an (optional) output stage 132, and an (optional) protection stage 133. The functions of these various stages / units are as follows:

[0050] The main functions of the control stage 130 are to generate (or receive) an AC signal having a specific frequency and to amplitude modulate the current flowing through the transmitting coil, thereby controlling the effective value of the fundamental wave of the AC signal. The AC signal output from the control stage 130 may have any waveform. The control stage 130 is typically implemented by a microcontroller, and its output signal is an AC signal, such as a PWM signal. The frequency of this PWM signal corresponds to the carrier frequency of the current in the transmitting coil and remains constant. To achieve flexible amplitude modulation of the carrier current in the transmitting coil, the duty cycle and phase of the PWM signal can be adapted. These manipulated variables allow control of the current in the transmitting coil. Figure 10 shows a graph of an exemplary output signal 140 (voltage signal) of the control stage 130 that generates a desired current signal.

[0051] The main functions of the signal processing stage 131 are filtering and amplification or attenuation of the signal. The control stage 130 typically does not have current capacity, and since the PWM signal still contains many harmonics, this stage is provided to further process the PWM signal. First, the signal processing stage 131 can remove harmonics contained in the carrier signal, as shown in Figure 11, and Figure 11 shows a graph of the output signal 141 of the signal processing circuit 131 having a low-distortion carrier and amplitude modulation. Additionally, flexible amplitude modulation is achieved by controlling the duty cycle and phase of the PWM signal, thereby enabling various pulse shaping and further improving the EMC performance of the signal. Figure 12 shows a graph of exemplary raised cosine modulation achieved by the proposed circuit diagram. Thanks to the flexible amplitude modulation and low-distortion carrier signal, and also thanks to the selected modulation (e.g., raised cosine modulation selected to be as similar as possible to a sine function), the modulated signal 142 has good EMC characteristics and meets stringent legal requirements. The signal strength can also be adjusted at this stage.

[0052] The signal processing stage 131 may include a filter stage and an amplification stage. Depending on the topology, the filter stage can preferably be a low-pass filter stage or a band-pass filter stage, which filters out high-frequency components from the AC signal and achieves a distortion-free, nearly sinusoidal waveform. In some cases, for example, if it is necessary to convert the AC signal from a single-ended signal to a difference signal for subsequent processing, a symmetrization process for the AC signal can also be provided.

[0053] Amplification stages are generally used to match the voltage levels between individual stages. This allows for both amplification and attenuation of the desired signal. Since a PWM signal generated by μC typically has only a small signal amplitude, the function of the amplification stage in this case is to amplify the amplitude of the AC signal. Thus, the output stage can later achieve the current strength specified in the transmitting coil. For this purpose, in the simplest case, an amplification circuit preferably consisting of an operational amplifier amplifies the AC signal to a larger amplitude, but smaller signal amplitudes are also possible. In some cases, this function can be taken over by a filter stage.

[0054] The transmitting coil of a DIPS typically requires a specific drive control current. If the current drive capability of the signal processing stage 131 is insufficient, the signal processing stage 131 and the output stage 132 can be cascaded to achieve sufficient current drive capability. The output stage 132 corresponds to the last stage of the power amplifier and ensures that the required current is supplied to the transmitting coil. Generally, various topologies can be used here. These may be, for example, a push-pull output stage, a push-pull circuit, or an inverter circuit.

[0055] The current transmission mode may induce an overvoltage in the transmission coil of the alignment device. In this case, it is advantageous to protect the drive control current circuit by cascading protection stages 133, for example, by an overvoltage protection circuit (OVP), in order to protect the susceptible electronic device.

[0056] Figure 13 shows a block diagram of an exemplary embodiment of the signal processing stage 131, particularly to illustrate the basic functional method of pulse shaping. The graph shown in Figure 14 shows a binary data stream 150 having information to be superimposed and modulated onto, for example, a aligning magnetic field generated by a transmitting coil. This allows the information to be transmitted to a vehicle-side inductive charging device, for example, to transmit information about a stationary inductive charging device.

[0057] The binary data stream 150 is input to the pulse shaping filter 151 to generate the desired envelope 152 shown in the graph in Figure 15. Compared to the binary data stream 150 shown in Figure 14, the envelope 152 is significantly smoother and therefore has better EMC characteristics. It is worth mentioning that the generation of the signal 152 shown in Figure 15 can be done, for example, using a pulse shaping filter implemented in a microcontroller. Alternatively, the waveform can be generated in advance in a computer and stored in the microcontroller.

[0058] The duty cycle (duty ratio) and phase of the PWM signal are adjusted in the setting unit 153 to correspond to signal 152. When the PWM signal is properly set, the amplitude-modulated carrier signal 154 (AC signal) shown in Figure 16 is obtained, meaning that signal 152 is amplitude-modulated and superimposed on the carrier wave.

[0059] The duty cycle of a PWM signal corresponds to the amplitude of the carrier signal. Depending on the subsequent electrical circuits (filters, amplifiers), this relationship can be described as a function: amplitude = f(duty cycle). Preferably, this may be: amplitude = k × (abs(duty cycle - 0.5)). The larger the duty cycle, the larger the carrier amplitude. Phase adjustment of the PWM signal corresponds to the case where the envelope is less than zero, as shown by the circle in Figure 15. Therefore, to make the carrier amplitude negative, the PWM signal is phase-shifted by 180°.

[0060] The type of pulse shaping filter, the parameter settings of the pulse shaping filter, and the modulation depth can generally be flexibly adjusted.

[0061] The duty cycle and phase of a PWM signal with amplitude = f (duty cycle) can be generated in a microcontroller. Alternatively, they can be generated in advance, for example, in a computer, and stored in the microcontroller.

[0062] In a preferred embodiment, the filter stage can generate a low-distortion sinusoidal signal. The drive control circuit according to the present invention is further excellent in terms of its simple structure, high accuracy, high EMC, and high stability. Thanks to these characteristics, an alignment device based on this driver circuit can be easily incorporated into a GA. Pulse shaping can be achieved by controlling the AC output section of the control stage. The goal is to suppress the side ropes of the modulated signal. Sinc filters, raised cosine filters, and Gaussian filters are suitable for effective implementation of pulse shaping.

[0063] The control PWM signal supplied by the μC generally has a rectangular waveform and a small signal amplitude, for example, 0 to 3.3V. The filter stage is used to filter out high-frequency components from the output signal of the control stage, thereby generating a nearly sinusoidal signal with the frequency of the corresponding transmitting coil. This can be achieved, for example, by a low-pass filter circuit or preferably a band-pass filter circuit. To achieve the necessary attenuation of harmonics, especially when starting from a rectangular PWM signal as the output signal, the filter may include multiple stages of first order or higher. The advantage of a band-pass filter stage is that it can effectively filter out low frequencies in this case. Interference frequencies are generated by harmonics of components with lower switching frequencies, for example, DC-DC converters. Furthermore, for the same number of stages, a band-pass filter circuit can usually achieve a steeper filter curve. The filter circuit can also generate amplification and offset of the output signal, which has the advantage of eliminating the need for an additional amplifier stage.

[0064] PWM output signals generally have only small signal amplitudes. Therefore, it is impossible to generate large coil currents. Consequently, amplification of the transmitted signal is necessary. For example, the signal can be amplified from 0V to 12V, but other amplification methods are also possible. In this frequency range, active filter circuits with operational amplifiers are generally preferred. This is because active filter circuits have the advantage of not requiring larger and more expensive components compared to passive filter circuits. As with DIPS, when the transmitted signal is, for example, in the kHz range, a disadvantage of a passive filter circuit of the same order as an active filter circuit is that (in the case of an LC filter) it requires a relatively large inductance value. This negatively impacts cost and configuration space. The dynamic characteristics of an active filter circuit can be adjusted through the selection of parameter values ​​(RC size adjustment). In this case, there is a high demand for dynamic characteristics in order to enable good pulse shaping.

[0065] The output stage can be implemented simply and inexpensively. In a Class B / AB amplifier, two or more transistors are used, each biased to conduct for only half a wave. In this case, the BJTs receive input signals with the same amplitude but a 180° phase shift. MOSFETs or preferably bipolar transistors (BJTs) can be used as transistors. Compared to Class A amplifiers, Class B and Class AB amplifiers have the advantage of reducing losses in the form of heat because individual transistors conduct throughout the entire period. This circuit can be assembled using BJTs of the same conductivity type (e.g., two NPNs) or BJTs with complementary conductivity types (NPN, PNP).

[0066] The connected transmitting coil may have a center tap. In this case, the inductance with a center tap is the transmitting coil. The role of the inductance with a center tap is to recombine the two 180° phase-shifted output signals of the two BJTs that supply power for the load. In this case, the load current is distributed to the two BJTs. The emitter terminals of the two illustrated NPN-BJTs are connected to GND via resistors for this purpose. The amplification of the output current can be set via the values ​​of these resistors. The positive half-wave is amplified by one transistor, and the negative half-wave is amplified by the other transistor. The base quiescent current can be set via resistors R1 and R2. This also enables AB operation. This is advantageous because it avoids distortion when the transistor input signal crosses zero. The connected transmitting coil does not have to have a center tap. For this reason, an unconnected circuit portion is used to circuit-technically simulate the center tap.

[0067] A symmetrizer can be used to operate a push-pull output stage from the single-ended output signal of the filter stage. The two NPN transistors must be driven by an inversely phased input signal, as described above. Therefore, the circuit should be designed to generate two signals of the same amplitude but phase-shifted by 180° from the filter output signal. These output signals are then applied to the collector and emitter resistors, respectively. An alternative option for generating the drive control signals for the output stage transistors is to generate the drive control signals using a drive transformer with a center tap.

[0068] The output stage can also be implemented using an integrated circuit (IC). For example, a high-current operational amplifier (OP amp) in a voltage follower circuit can be used as the output stage. The filter stage and output stage are implemented separately by other OP amps. In this case, amplification can also be generated by a bandpass filter circuit.

[0069] When an operational amplifier with high current capacity is used directly as a filter operational amplifier, even the output stage can be omitted, because it can also generate the corresponding coil current. However, a drawback of this solution is that multi-channel operational amplifiers, especially those with high current capacity, are relatively expensive depending on the number of stages. For this reason, a solution using an inexpensive amplifier-operation amplifier for the filter circuit is preferable. In this case, only one high-current operational amplifier is required in the output stage. In this case, the output stage is a high-current operational amplifier in a voltage follower circuit.

[0070] Therefore, in summary, the present invention proposes a control and drive concept for a transmitting coil of an inductive charging device alignment device, which supplies a sinusoidal carrier current to the transmitting coil with low distortion and high amplitude modulation freedom. The resulting transmitting coil magnetic field can meet stringent EMC requirements and improve system stability.

Claims

1. In the energy transmission operation, a first energy coil generates an alternating magnetic field for inductively transmitting energy to the second energy coil of the second inductive charging device, An alignment device comprising at least one transmitting coil for generating an alignment magnetic field for mutually identifying the relative alignment of the energy coils in an alignment operation, A drive control device for generating a drive control current for driving and controlling at least one of the transmitting coils, An inductive charging device comprising, the drive control device is Receiving or generating an AC signal having a carrier frequency, To generate an amplitude-modulated AC signal, the AC signal is pulse-shaped by multiplying it with a pulse signal. An inductive charging device configured to generate the drive control current by filtering the amplitude-modulated AC signal to attenuate its harmonics.

2. The inductive charging device according to claim 1, characterized in that the drive control device is configured to generate a pulse width modulated signal as an AC signal.

3. The inductive charging device according to claim 1 or 2, characterized in that the drive control device is configured to perform low-pass filtering or band-pass filtering of the amplitude-modulated AC signal.

4. The inductive charging device according to any one of claims 1 to 3, characterized in that the drive control device is configured to set the effective value of the current by setting the duty cycle and phase of the AC signal, and / or to amplitude modulate it.

5. The inductive charging device according to any one of claims 1 to 4, characterized in that the drive control device is configured to pulse shape the amplitude-modulated AC signal using pulse shaping filters, particularly a raised cosine filter, a root-raised cosine filter, a sinc filter, and a Gaussian filter.

6. The inductive charging device according to any one of claims 1 to 5, characterized in that the drive control device is configured to amplify or attenuate the amplitude-modulated and filtered AC signal.

7. The inductive charging device according to any one of claims 1 to 6, characterized in that the drive control device is configured to amplify the amplitude-modulated and filtered AC signal.

8. The inductive charging device according to any one of claims 1 to 7, characterized in that the drive control device comprises a signal generation unit, a filter unit, and an amplification unit.

9. The inductive charging device according to any one of claims 1 to 8, characterized in that the drive control device has an overcurrent protection circuit and / or an overvoltage protection circuit on the output side.

10. The alignment device has a plurality of transmitting coils, particularly four or five transmitting coils, to generate one alignment magnetic field each as an alternating magnetic field having a different carrier frequency. The inductive charging device according to any one of claims 1 to 9, characterized in that the drive control device is configured to generate different drive control currents for each of the transmitting coils.

11. The induction charging device according to any one of claims 1 to 10, characterized in that the induction charging device is a stationary induction charging device for installation on and / or in the ground.

12. A system for inductive energy transmission comprising an inductive charging device according to any one of claims 1 to 11, and another inductive charging device, in particular a mobile inductive charging device for mounting on and / or inside a vehicle, wherein the other inductive charging device is In the energy transmission operation, a second energy coil for receiving energy inductively transmitted from the first energy coil, In the aforementioned alignment operation, the alignment device includes at least one receiving coil for detecting the alignment magnetic field and for mutually identifying the relative alignment of the energy coils, A system that has

13. A method for generating a drive control current for driving and controlling at least one transmitting coil of an alignment device of an inductive charging device, The inductive charging device includes, in energy transmission operation, a first energy coil for generating an alternating magnetic field for inductively transmitting energy to a second energy coil of a second inductive charging device, and in alignment operation, an alignment device equipped with at least one transmitting coil for generating an alignment magnetic field for mutually identifying the relative alignment of the energy coils. Receiving or generating an AC signal having a carrier frequency, To generate an amplitude-modulated AC signal, the AC signal is pulse-shaped by multiplying it with a pulse signal. Filtering is performed to attenuate the harmonics of the amplitude-modulated AC signal. A method for generating the drive control current by the means described above.

Images