Wireless charging device and method

Abstract

The invention discloses a sensorless wireless charging device and method. According to a traditional wireless charging device, real-time monitoring of various charging data of an energy transmitting end and an energy receiving end is achieved through a sensor, and data receiving and transmitting are completed in a certain communication mode. However, due to environmental interference, power supply faults, compatibility problems and other reasons, sensing and communication functions are easy to lose efficacy, so that the wireless charging device cannot operate safely and stably. In order to solve the problem, based on a transmitting-receiving double-end high-order compensation network, the invention provides a dual-working-frequency automatic switching wireless charging device adaptive to a power battery charging curve and a corresponding dual-working-frequency switching charging method. The wireless charging device not only gets rid of dependence on sensing and communication components so as to achieve high reliability, but also ensures that the selected working frequency conforms to a frequency band specified by an industrial standard, and has the competitive advantages of allowing bidirectional energy flow and zero-phase-angle high-efficiency work, reducing the number of elements of the wireless charging device and the like.

Description

Technical Field

[0001] This application generally relates to the field of wireless charging technology, and more specifically, to a wireless charging device and method. Background Technology

[0002] Currently, many electronic devices and vehicles widely use traditional wired charging. However, this method has some inherent limitations. For example, frequent plugging and unplugging can lead to connector wear, cable aging, and compatibility issues between different devices. These factors reduce the efficiency of wireless charging devices and may cause safety hazards such as leakage and overheating. Wireless charging technology, with its advantages of being contactless, convenient, and safe, has demonstrated its enormous potential and practical value in many fields in recent years. Manufacturers of automobiles, robots, and drones are actively integrating wireless charging technology into their products to meet market demand for efficient, safe, and user-friendly charging solutions.

[0003] Currently, most wireless charging technologies in practical applications employ the principle of electromagnetic induction. This technology achieves energy transfer through magnetic coupling, utilizing changes in the magnetic field generated by the coupling coil to induce an electromotive force, thereby conducting electrical energy. Existing wireless charging devices typically rely on sensors to monitor the charging status of the energy transmitter and receiver, and use communication technology to achieve real-time data exchange. However, wireless charging devices containing sensors may experience performance degradation or even complete failure of the sensors and communication modules due to factors such as environmental noise, power supply issues, or device compatibility, affecting the safety and stability of the charging process. Furthermore, removing the sensors would make it difficult for the wireless charging device to recognize and adapt to the diverse needs of the battery during the charging process, as different charging stages often require different power supply strategies.

[0004] Given the aforementioned challenges, developing a novel sensorless wireless charging technology capable of constant voltage, constant current, and autonomous mode switching is crucial. However, low-order compensation networks often operate only in a single output mode (constant voltage or constant current) unless network reconfiguration is permitted. Existing methods struggle to guarantee that high-order compensation networks maintain zero-phase operation in both target output modes, posing a challenge to the system design of sensorless wireless charging technology. Summary of the Invention

[0005] This application provides a wireless charging device and method that can achieve dual-mode (constant voltage charging mode and constant current charging mode) output and autonomous mode switching of the energy receiving end without the use of sensors.

[0006] This application provides a wireless charging device for charging load devices such as electric vehicles, robots, and drones. The wireless charging device includes a primary-side energy transmitter and a secondary-side energy receiver. The primary-side energy transmitter includes a primary-side energy transmitting coil, a primary-side compensation network, and a primary-side power converter. The secondary-side energy receiver includes a secondary-side energy receiving coil, a secondary-side compensation network, and a secondary-side power converter. The secondary-side energy receiver does not include a sensor for detecting the charging status of the load device. The primary-side power converter is connected to an input power source, and the secondary-side power converter is coupled to the load device for charging. The primary-side energy transmitting coil and the secondary-side energy receiving coil wirelessly transfer energy through mutual inductance. The primary-side power converter converts the input power into AC voltage and provides the AC voltage to the primary-side compensation network. The primary-side compensation network transmits the AC voltage to the primary-side energy transmitting coil after resonant transformation. The primary-side energy transmitting coil induces an AC voltage in the secondary-side energy transmitting coil wirelessly through mutual inductance and transmits the AC voltage to the secondary-side compensation network. After resonant transformation by the secondary-side compensation network, the AC voltage is provided to the secondary-side power converter, which then converts it into DC output voltage for charging the load equipment.

[0007] In this application's wireless charging device, "wireless" means that energy is transferred wirelessly between the primary-side energy transmitting coil and the secondary-side energy receiving coil via mutual inductance. Therefore, there is no physical connection between the primary-side energy transmitting coil and the secondary-side energy receiving coil. However, within the primary-side energy transmitting end or the secondary-side energy receiving end, they can be connected via wired physical connections, respectively.

[0008] Preferably, the input power supply is an input DC power supply, the primary-side power converter includes a primary-side inverter containing switching devices, and the secondary-side power converter includes a rectifier containing switching devices.

[0009] Preferably, the primary-side energy transmitter and the secondary-side energy receiver are symmetrical in structure. The inductance value of the energy transmitting coil in the primary-side energy transmitter is consistent with the inductance value of the energy receiving coil in the secondary-side energy receiver. The topology and inductance / capacitance values ​​of the compensation network in the primary-side energy transmitter are consistent with the topology and inductance / capacitance values ​​of the compensation network in the secondary-side energy receiver, respectively. Furthermore, both the power converter in the primary-side energy transmitter and the power converter in the secondary-side energy transmitter use fully controlled switching devices to enable bidirectional energy flow in the wireless charging device.

[0010] Preferably, the primary-side compensation network and the secondary-side compensation network are in a symmetrical CLC-CLC or LCC-LCC form, where C represents the compensation capacitor and L represents the compensation inductor. The inverter at the primary-side energy transmitter or the rectifier at the secondary-side energy receiver may each consist of only one stage of converter.

[0011] Preferably, the wireless charging device is configured to charge the load device through a two-stage constant current-constant voltage charging process. The first stage of the charging process is constant current charging, where the primary-side energy transmitter operates at a constant current frequency, and the secondary-side power converter charges the load device with a constant current. During this first stage, the input current of the primary-side compensation network increases with the charging voltage of the secondary-side power converter, and the wireless charging device determines whether the input current has increased to a mode switching point. When the input current reaches the mode switching point, the operating frequency of the primary-side energy transmitter switches from a constant current frequency to a constant voltage frequency, and the charging process enters the second stage, which is constant voltage charging. Charging is performed at a constant voltage frequency, the charging voltage of the secondary-side power converter remains constant, and the charging current of the primary-side compensation network gradually decreases. The wireless charging device determines whether the input current of the primary-side compensation network has decreased to a charging stop point, and the charging process ends when the input current decreases to the charging stop point.

[0012] Preferably, the mode switching point of the input current is associated with the battery characteristics of the load device and the impedance characteristics of the wireless charging device.

[0013] Furthermore, this application also provides a wireless charging system, which includes a control device and the aforementioned wireless charging device. The control device includes an input voltage and current sampling circuit, a controller, and a drive circuit. The controller includes a charging parameter setting module and a mode switching module. The charging parameter setting module sets or pre-sets parameters for switching the operating frequency of the wireless charging device, such as a constant current operating frequency and a constant voltage operating frequency, as well as a mode switching point and a charging stop point. The mode switching module switches the charging mode of the wireless charging device from a constant current charging mode to a constant voltage charging mode based on the mode switching point and the charging stop point.

[0014] This application also provides a charging method for a wireless charging device in a second aspect. The charging method charges the load device through a two-stage constant current-constant voltage charging process, switching the operating frequency during the charging process. The charging method includes:

[0015] (1) The first stage of the charging process is constant current charging. The operating frequency of the primary-side energy transmitter of the wireless charging device is the constant current operating frequency. The secondary-side power converter of the wireless charging device charges the load device with a constant current. In the first stage, the input current of the primary-side compensation network in the primary-side energy transmitter will increase with the increase of the charging voltage of the secondary-side power converter. In the first stage of the charging process, it is determined whether the input current has increased to the mode switching point; and...

[0016] (2) When the input current increases to the mode switching point, the operating frequency of the primary side energy transmitter switches from constant current operating frequency to constant voltage operating frequency, and the charging process of the wireless charging device enters the second stage. The second stage is constant voltage charging, which is performed at a constant voltage operating frequency. The charging voltage of the secondary side power converter remains constant, while the charging current of the primary side compensation network gradually decreases. In the second stage of the charging process, it is determined whether the input current of the primary side compensation network has dropped to the charging stop point. When the input current drops to the charging stop point, the charging process ends.

[0017] Preferably, in the charging method, the mode switching point of the input current is associated with the battery characteristics and the impedance characteristics of the wireless charging device, and the mode switching point and the charging stop point are determined according to the following steps:

[0018] The parameters X of each compensation element in the primary-side compensation network and the secondary-side compensation network of the wireless charging device are... t1 To X t4 X r1 To X r4 The values ​​of mutual inductance M and the resistance R of the load device are input into the following formulas (1), (2), (3), and (4) to solve for parameters A and B:

[0019] The current gain of the wireless charging device relative to the input voltage of the primary-side compensation network is expressed by formula (1):

[0020]

[0021] In formula (1), X = -jω cc MX t3 X r3 ,

[0022] Y1=(ω cc M) 2 (X t3 +X t4 )[jR-(X r3 +X r4 )],

[0023] Y2=[(Xt1 +X t2 (X) t3 +X t4 )+X t3 X t4 ],

[0024] Y3=[j(X r1 +X r2 +X r3 )R-(X r1 +X r2 (X) r3 +X r4 )-X r3 X r4 ],

[0025] M represents the mutual inductance between the primary and secondary energy emitting coils.

[0026] R represents the resistance of the load device.

[0027] Among them, jX ti (i = 2, 3, 4) represent the compensation elements L1, C1, C2, and C3 of the primary compensation network. t The impedance form, jX ri (i = 2, 3, 4) represents the compensation element C of the secondary side compensation network. r The impedance forms of C2 and L2, and the compensation elements in the primary and secondary compensation networks are arranged in a T-type equivalent network form, jX t1 and jX r1 Let i represent the impedances of the primary and secondary energy transmitting coils of the wireless charging device, respectively, and define the index i ∈ {1, 2, 3, 4}.

[0028] The simplified form of formula (1) is:

[0029]

[0030] The voltage gain of the wireless charging device relative to the input voltage is expressed by formula (3):

[0031]

[0032] In formula (3), X = -jω cv MX t3 X r3 R,

[0033] Y4=(ω cv M) 2 (X t3 +X t4 )[jR-(X r3 +X r4 )],

[0034] Y5=[(X t1 +X t2 (X) t3 +X t4 )+X t3 X t4 ],

[0035] Y6=[j(X r1 +X r2 +X r3 )R-(X r1 +X r2 (X) r3 +X r4 )-X r3 X r4 ],

[0036] The simplified form of formula (3) is:

[0037]

[0038] Solve for the constant current operating frequency, which makes |B / A| in formula (2) take the minimum value; solve for the constant voltage operating frequency, which makes |A / R| / |B / R| in formula (4) take the minimum value, thereby determining the constant current operating frequency and the constant voltage operating frequency respectively;

[0039] Then, based on the battery characteristics of the load device, the optimal switching load for constant current charging mode and constant voltage charging mode is determined, and the input current of the primary-side energy emitter corresponding to this switching load is marked as the mode switching point for constant current charging and constant voltage charging; and

[0040] The equivalent load at which the battery is fully charged is determined based on the battery characteristics, and the input current at the primary side energy emitter corresponding to the equivalent load is marked as the charging stop point.

[0041] The foregoing summary of this application and the following detailed description of exemplary embodiments will be better understood by reading in conjunction with the accompanying drawings. Illustrative embodiments of this disclosure are shown in the drawings to illustrate this application. However, it should be understood that this application is not limited to the precise arrangements and means shown in the drawings. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a wireless charging device according to an embodiment of this application.

[0043] Figure 2A and 2B These are circuit topology diagrams of the high-order compensation network of the wireless charging device according to embodiments of this application.

[0044] Figure 3This is a T-type equivalent model diagram of the wireless charging device according to the embodiments of this application, used for calculating the constant current operating frequency and constant voltage operating frequency.

[0045] Figure 4 This is a flowchart of the parameter settings and charging process of a charging method for a wireless charging device with dual operating frequency switching according to an embodiment of this application.

[0046] Figure 5 This is a schematic diagram of a wireless charging device with dual operating frequency switching operation according to an embodiment of this application. Detailed Implementation

[0047] The specific embodiments of this application are described below with reference to the accompanying drawings.

[0048] Figure 1 This is a schematic diagram of the energy flow of a wireless charging device according to an embodiment of this application.

[0049] like Figure 1 As shown, this application provides a wireless charging device 10 in a first aspect. The wireless charging device can be applied to load devices or load clusters such as electric vehicles, robots, and drones to charge them. The wireless charging device 10 includes a primary-side energy transmitter 100 and a secondary-side energy receiver 200. The primary-side energy transmitter 100 includes a primary-side energy transmitting coil 103, a primary-side compensation network 102, and a primary-side power converter 101. The secondary-side energy receiver includes a secondary-side energy receiving coil 203, a secondary-side compensation network 202, and a secondary-side power converter 201. The primary-side power converter is connected to an input power source, and the secondary-side power converter is coupled to the load device for charging. The primary-side energy transmitting coil and the secondary-side energy receiving coil wirelessly transfer energy through mutual inductance. Furthermore, the secondary-side energy receiver does not include a sensor for detecting the charging status of the load device.

[0050] To avoid ambiguity, the definitions of primary and secondary sides in this article are further clarified here: when energy flows from the power grid to the load device, the primary side refers to the component closer to the power grid side, and the secondary side refers to the component closer to the load device side; conversely, when energy flows from the load device to the power grid, the primary side refers to the component closer to the load device side, and the secondary side refers to the component closer to the power grid side.

[0051] by Figure 1 Taking the left side as the primary side as an example, the DC bus voltage U i Indicates the input DC power supply, voltage U iThe AC voltage is converted to AC voltage by the primary-side power converter 101 and then supplied to the primary-side compensation network 102. In this embodiment, the primary-side power converter 101 is implemented as a primary-side inverter including switching devices S1, S2, S3, and S4. The primary-side compensation network 102 transmits the AC voltage to the primary-side energy transmitting coil 103 after resonant conversion, with an AC current i t The inductance of the primary-side energy emitting coil 103 is L. t In alternating current i t Under excitation, through the mutual inductance M between the primary energy emitting coil 103 and the secondary energy emitting coil 203, an alternating current i is induced in the secondary energy emitting coil 203. r And the alternating current i r The voltage is transmitted to the secondary-side compensation network 202, and after resonant transformation by the secondary-side compensation network 203, it is supplied to the secondary-side power converter 201, which then converts (e.g., rectifies) it into a DC output voltage U. o This device is used to charge load devices or load clusters such as electric vehicles, robots, and drones. The secondary-side power converter 201 includes a rectifier comprising switching devices S5, S6, S7, and S8. Parasitic resistance R may also be included at the primary-side energy transmitter 100 and the secondary-side energy receiver 200. t .

[0052] The specific details of the resonance transformation in the primary-side compensation network 102 and the secondary-side compensation network 202 will be referred to below respectively. Figure 3 describe.

[0053] In other embodiments of this application, depending on the specific application, the wireless charging device 10 can also be connected to an AC power source, such as a single-phase or three-phase ordinary household or industrial power supply. In this case, the primary-side power converter 101 can be replaced with a suitable AC-DC rectifier. On the other hand, if the specific load uses AC voltage for charging, the output of the secondary-side power converter 201 can be replaced with an AC output voltage. In this case, the secondary-side power converter 201 can be replaced with a suitable AC-DC-AC converter. Depending on the actual application, in some embodiments, the load device or load cluster can be connected to the secondary-side energy receiver 200 wired or wirelessly for charging.

[0054] To meet the bidirectional energy flow requirements of the wireless charging device of this application, the structures of the primary-side energy transmitter and the secondary-side energy receiver are symmetrical. That is, the inductance value of the energy transmitting coil in the primary-side energy transmitter should be consistent with the inductance value of the energy transmitting coil in the secondary-side energy receiver. Similarly, the topology and inductance / capacitance values ​​of the compensation network in the primary-side energy transmitter should also be consistent with those of the compensation network in the secondary-side energy receiver. Furthermore, both the power converter in the primary-side energy transmitter and the power converter in the secondary-side energy receiver should use fully controllable switching devices. Fully controllable devices, also known as self-turn-off devices, are power electronic devices that can be controlled to both turn on and off via a control signal, such as gate turn-off thyristors (GTOs), power field-effect transistors (FETs), and insulated-gate bipolar transistors (IGBTs), etc.

[0055] like Figure 1 As shown, the wireless charging device can typically use only a single-stage converter as the transmitter (i.e., primary-side energy transmitter 100) or receiver (i.e., secondary-side energy receiver 200) of an inverter (e.g., switching devices S1, S2, S3, S4) or rectifier (e.g., switching devices S5, S6, S7, S8), eliminating the need for an additional DC-DC buck-boost module for secondary power conversion. Fewer power conversions reduce the number of components in the wireless charging device, improve charging efficiency, and reduce costs. Generally, if a synchronous rectifier is used, a symmetrical topology including the energy transmitting coils, compensation network, and power converter at both the primary and secondary sides can support bidirectional wireless charging.

[0056] Specifically, such as Figure 2A and Figure 2B As shown in the embodiments of this application, if the wireless charging device 10 is required to support bidirectional energy transmission, the primary-side compensation network 102 or the secondary-side compensation network 202 included in the wireless charging device 10 can be either CLC-CLC or LCC-LCC, which are two symmetrical forms.

[0057] Figure 2A and Figure 2B These are circuit topology diagrams of the high-order compensation network of the wireless charging device 10 according to embodiments of this application, with parasitic resistance R omitted in the diagrams. t . Figure 2A This represents a compensation network in the CLC-CLC symmetric form, while Figure 2B This represents a compensation network in symmetrical LCC-LCC form. Here, C represents the compensation capacitor and L represents the compensation inductor. If energy is only required to flow from the grid to the load device, the topology of the compensation network or the values ​​of the compensation elements can be asymmetrical.

[0058] exist Figure 2A and Figure 2B In the middle, v i express Figure 1 DC bus voltage U i The AC voltage obtained after conversion by the primary-side inverter can represent the output of the primary-side power converter 101; v o express Figure 1 DC output voltage U o The AC voltage that exists before being converted by the secondary rectifier can represent the input of the secondary power converter 201. Figure 2A and Figure 2B The working process and reference of the wireless charging device 10 shown Figure 1 The working process is basically the same, and the connection method and working principle of CLC-CLC compensation network or LCC-LCC compensation network are known to those skilled in the art, so they will not be repeated here.

[0059] Figure 3 This is a T-type equivalent model diagram of the wireless charging device 10 according to an embodiment of this application, used for calculating the constant current operating frequency and constant voltage operating frequency. The parasitic resistance Rt is omitted in the diagram.

[0060] like Figure 3 As shown, with Figure 2A and Figure 2B The two high-order symmetric compensation networks involved correspond to jX ti (i = 2, 3, 4) represent the three compensation elements L1, C1, C2, and C3 of the primary compensation network 102. t The impedance form; similarly, jX ri (i = 2, 3, 4) represent the three compensation elements C of the secondary side compensation network 202. r The impedance forms of C2 and L2. The components of these two sets of compensation networks are arranged in a T-type equivalent network form. jX t1 and jX r1 Let represent the impedances of the primary-side energy transmitting coil 103 and the secondary-side energy transmitting coil 203, respectively. Define the index i ∈ {1, 2, 3, 4}, and define the wireless charging device 10 relative to the input voltage v. i The current gain can be expressed as:

[0061]

[0062] In formula (1), X = -jω cc MX t3 X r3 ,

[0063] Y1=(ω cc M) 2 (Xt3 +X t4 )[jR-(X r3 +X r4 )],

[0064] Y2=[(X t1 +X t2 (X) t3 +X t4 )+X t3 X t4 ],

[0065] Y3=[j(X r1 +X r2 +X r3 )R-(X r1 +X r2 (X) r3 +X r4 )-X r3 X r4 ],

[0066] M represents the mutual inductance between the primary energy emitting coil 103 and the secondary energy emitting coil 203, and R represents the resistance of the load device.

[0067] The simplified form of formula (1) can be written as:

[0068]

[0069] In formula (2), A represents the real part of the denominator of formula (1), and B represents the imaginary part of the denominator of formula (1).

[0070] The wireless charging device 10 is compared to the input voltage v i The voltage gain can be expressed as:

[0071]

[0072] In formula (3), X = -jω cv MX t3 X r3 R,

[0073] Y4=(ω cv M) 2 (X t3 +X t4 )[jR-(X r3 +X r4 )],

[0074] Y5=[(X t1 +X t2 (X) t3 +X t4 )+X t3 Xt4 ],

[0075] Y6=[j(X r1 +X r2 +X r3 )R-(X r1 +X r2 (X) r3 +X r4 )-X r3 X r4 ],

[0076] The simplified form of formula (3) can be written as:

[0077]

[0078] In formula (4), A / R represents the real part of the denominator of formula (4), and B / R represents the imaginary part of the denominator of formula (4).

[0079] About jX ti and jX ri How can the value selection method adapt to both constant current and constant voltage operating modes? Figure 3 Find the constant current operating frequency ω CC and constant voltage operating frequency ω CV The possible values ​​will be referenced below. Figure 4 Detailed description.

[0080] Figure 4 This is a flowchart of the parameter settings and charging process of a charging method for a wireless charging device with dual operating frequency switching according to an embodiment of this application.

[0081] like Figure 4 As shown, this application also provides a charging method for a wireless charging device in a second aspect. The charging method adopts a constant current-constant voltage two-stage charging, and the operating frequency is switched during the charging process. The charging method includes: (1) In step 406, the first stage of the charging process of the wireless charging device is constant current charging, and the operating frequency of the primary side energy transmitter is the constant current operating frequency ω. CC The secondary-side power converter charges the load device with a constant current. In the first stage, the charging voltage v of the secondary-side power converter... o The current gradually increases with the increase of the battery power of the load device. In the first stage, since the overall efficiency of the wireless charging device is close to 1, the input current i of the primary-side compensation network... i The charging voltage v of the secondary power converter will be... o The increase is almost linear. In the first stage, in step 407, the wireless charging device determines the input current i. iHas it increased to the mode switching point, i.e., the preset value I? thr And (2) in step 408, determine when the input current i i Increase to preset value I thr At that time, the operating frequency of the primary side energy emitter is changed from the constant current operating frequency ω. CC Switch to constant voltage operating frequency ω CV The charging process then enters the second stage: constant voltage charging, which is performed at a constant voltage operating frequency. In this second stage, the charging voltage v of the secondary-side power converter... o The charging current i of the primary-side compensation network remains constant. i The current gradually decreases until the charging process shown in step 410 ends. In the second stage, as shown in step 409, the wireless charging device determines the input current i of the primary-side compensation network. i Whether the charging has stopped when the input current i i The charging process ends when the current drops to the charging stop point. The mode switching point of the input current (i.e., the preset value I) is... thr This is related to the battery characteristics of the load device and the impedance characteristics of the wireless charging device, as described below.

[0082] like Figure 4 As shown, according to an embodiment of this application, the wireless charging device can determine the above parameters by following the method below, so as to charge sequentially using constant current operating frequency and constant voltage operating frequency. First, the parameter determination method begins in step 401. In step 402, in Figure 3 The parameters of the symmetrical high-order resonant network in the wireless charging device will be input into formulas (1), (2), (3), and (4), that is, the parameters X of each compensation element in the primary-side compensation network and the secondary-side compensation network of the wireless charging device will be input into formulas (1), (2), (3), and (4). t1 To X t4 X r1 To X r4 The values ​​of mutual inductance M and resistance R of the load device are input into the above formulas (1), (2), (3), and (4) to solve for parameters A and B.

[0083] Then, in step 403, the constant current operating frequency ω is solved. CC This minimizes |B / A| in formula (2). Then, in step 404, the constant voltage operating frequency ω is calculated. CV This minimizes |A / R| / |B / R| in formula (4), thereby determining the constant current operating frequency ω. CC and constant voltage operating frequency ω CVNext, in step 405, the optimal constant current charging mode and constant voltage charging mode switching load can be determined based on the battery characteristics of the load device, and the input current of the primary-side energy transmitter corresponding to this switching load is marked as the mode switching point for constant current charging and constant voltage charging. Similarly, the equivalent load at which battery charging is complete is determined based on the battery characteristics, and the input current of the primary-side energy transmitter corresponding to the equivalent load is marked as the charging stop point. Thus, the parameter design of the dual-operating-frequency switching charging method for the wireless charging device of this application is completed.

[0084] In other words, Figure 4 The flowchart actually includes two methods: steps 401 to 405 are the parameter setting process for the wireless charging device of this application, while steps 406 to 410 are the charging process of the wireless charging device of this application on the load device. If the aforementioned parameters have been preset in the wireless charging device of this application, then when using the wireless charging device of this application to charge the load device, only the charging process described in steps 406 to 410 needs to be executed.

[0085] In the actual charging process of the wireless charging device of this application, the equivalent load of the battery in the load device continuously changes, and the current of the energy transmitter changes accordingly. The charging progress of the battery can be determined simply by detecting the operating current of the energy transmitter. Therefore, it is only necessary to install a current sensor at the energy transmitter, without the need to install a current sensor at the energy receiver to detect the charging status of the load device and transmit the charging status of the load device to the energy transmitter in real time for control. This is the meaning of "sensorless" as described in this application.

[0086] After charging begins, the wireless charging device initially operates at a constant current frequency, during which the battery is charged with a constant current. Every short time interval (depending on the sampling method and frequency), the input current is transmitted to the controller, which determines whether the input current exceeds a preset constant voltage / constant current switching point. If the current at the energy transmitter does not exceed the constant voltage / constant current switching point, the wireless charging device continues to operate in constant current charging mode. If the transmitter current exceeds the constant voltage / constant current switching point, the operating frequency of the wireless charging device will be changed from the constant current frequency ω. CC Switch to constant voltage operating frequency ω CV To begin charging, the wireless charging device enters a constant voltage charging mode. The battery will then be charged at a constant voltage. At very short time intervals, the input current is transmitted to the controller to determine if it exceeds a preset charging stop point. If the current at the energy transmitter does not fall below the charging stop point, the wireless charging device continues to operate in constant voltage charging mode. If the current at the energy transmitter falls below the charging stop point, the wireless charging device stops operating, and charging is complete.

[0087] Figure 5 This is a schematic diagram of a wireless charging system with dual operating frequency switching operation according to an embodiment of this application. Figure 5 As shown, the hardware structure of the wireless charging system according to an embodiment of this application includes a wireless charging device 10 and a control device 50.

[0088] The wireless charging device 10, also known as a power module, includes a primary-side energy transmitter 100 and a secondary-side energy receiver 200, such as... Figure 1 As shown. The primary-side energy transmitter 100 includes a primary-side energy transmitter coil 103, a primary-side compensation network 102, and a primary-side power converter 101. The secondary-side energy receiver includes a secondary-side energy receiver coil 203, a secondary-side compensation network 202, and a secondary-side power converter 201. In this embodiment, the primary-side power converter 101 includes a bus DC input power supply U. i The primary-side inverter includes switching devices S1, S2, S3, and S4. The secondary-side power converter 201 includes diode rectifiers D1, D2, D3, and D4 and an energy storage unit for the load device. The energy storage unit receives the DC output voltage U from the secondary-side power converter 201. o .

[0089] The control device 50 includes an input voltage and current sampling circuit 501, a controller, and a drive circuit 504. The controller includes a charging parameter setting module 503 and a mode switching module 502. The input voltage and current sampling circuit 501 is connected to the bus DC input power supply U via, for example, a capacitor. i To detect its voltage or current. The charging parameter setting module 503 refers to... Figure 3 The T-type equivalent model diagram of the wireless charging device used for calculating the constant current operating frequency and constant voltage operating frequency is based on the reference... Figure 4 The parameter determination method described in steps 402-405 is used to set or pre-set parameters of the dual-operating-frequency switching charging method of the wireless charging device according to the embodiments of this application, such as the constant current operating frequency ω. CC and constant voltage operating frequency ω CV The mode switching module 502 switches the charging mode of the wireless charging device 10 based on the mode switching point and the charging stop point: constant current charging mode or constant voltage charging mode. The charging parameter setting module 503, the mode switching module 502, and the driving circuit 504 can be coupled to the primary side energy transmitting coil 103, the primary side compensation network 102, and the primary side power converter 101 of the primary side energy transmitting end 100, respectively, to control the operating frequency and / or charging mode of the primary side energy transmitting end 100.

[0090] Figure 5The direct physical connection between the charging parameter setting module 503, the mode switching module 502, and the drive circuit 504 and the wireless charging device 10 is not shown in the diagram. It can be understood that the calculation results of the charging parameter setting module 503 and the mode switching module 502 will ultimately be reflected in the output of the drive circuit 504, and the output of the drive circuit 504 will be connected to the signal input terminals of the four switching devices S1, S2, S3, and S4 in the primary-side power converter 101 to achieve mode selection and switching.

[0091] As described above, this application provides a sensorless wireless charging device for power replenishment in applications such as electric vehicles, robots, and drones. The wireless charging device includes a set of symmetrical high-order compensation networks, a set of symmetrical transmit-receive coils, a set of bidirectional power converters, and other DC components. The wireless charging device has the competitive advantage of high reliability, eliminating the need for controllers, sensors, and communication components. Furthermore, the wireless charging device enables bidirectional energy flow; that is, applications such as electric vehicles, robots, and drones, or other load devices, can both act as energy receivers for charging and as energy providers supplying power to other devices.

[0092] Preferably, the wireless charging device achieves two operating frequencies (i.e., constant current operating frequency ω) by detecting a current threshold. CC and constant voltage operating frequency ω CV The automatic switching of the constant current charging mode and the constant voltage charging mode are achieved through the control device.

[0093] In the wireless charging device, either of the two operating frequencies can meet the defined range of industry standards, while ensuring that the wireless charging device maintains zero-phase angle operation. The industry standards depend on the specific application; for example, for wireless charging of electric vehicles, the applicable standards are SAE J2954 and IEC 61980. For other load devices, there are other applicable (or future promulgated) industry standards. Furthermore, according to the scheme of the present invention, following the parameter calculation method of the aforementioned formulas (1)-(4), the wireless charging system naturally possesses the zero-phase angle operating condition.

[0094] In the wireless charging device, a single DC bus can support multiple charging loads, significantly reducing assembly space and cost to meet the needs of multi-load application scenarios such as parking lots and helipads. For example, Figure 1 DC bus voltage U i As a common input DC power supply, the DC output voltage U starts from the switching devices S1, S2, S3, S4 and continues to the right. o All the previous components were in multiple sets, which allowed multiple loads to be charged separately or in parallel.

[0095] In addition, the sensorless wireless charging device includes a charging method with dual operating frequency switching suitable for constant current-constant voltage two-stage charging.

[0096] To provide a more comprehensive understanding of the concepts of the present invention, numerous specific details of embodiments of the invention have been described above. However, it will be apparent to those skilled in the art that the inventive concepts within this disclosure can be practiced without these specific details. In other instances, features well-known in the art have not been described in detail to avoid unnecessarily complicating this disclosure.

Claims

1. A wireless charging device, comprising a primary-side energy transmitter and a secondary-side energy receiver, in, The primary side energy transmitter includes a primary side energy transmitter coil, a primary side compensation network, and a primary side power converter. The secondary side energy receiver includes a secondary side energy receiver coil, a secondary side compensation network, and a secondary side power converter. However, the secondary side energy receiver does not include a sensor for detecting the charging status of the load device. The primary-side power converter is connected to the input power supply, the secondary-side power converter is coupled to the load device to charge it, and the primary-side energy transmitting coil and the secondary-side energy receiving coil transmit energy wirelessly through mutual inductance. The primary-side power converter converts the input power into AC voltage and provides the AC voltage to the primary-side compensation network. The primary-side compensation network transmits the AC voltage to the primary-side energy transmitting coil after resonant transformation. The primary-side energy transmitting coil induces an AC voltage in the secondary-side energy transmitting coil wirelessly through mutual inductance and transmits the AC voltage to the secondary-side compensation network. After resonant transformation by the secondary-side compensation network, the AC voltage is provided to the secondary-side power converter, which then converts it into a DC output voltage for charging the load equipment.

2. The wireless charging device according to claim 1, wherein the input power supply is an input DC power supply, the primary-side power converter includes a primary-side inverter containing switching devices, and the secondary-side power converter includes a rectifier containing switching devices.

3. The wireless charging device according to claim 1, wherein the structures of the primary-side energy transmitter and the secondary-side energy receiver are symmetrical, the inductance value of the energy transmitting coil in the primary-side energy transmitter is consistent with the inductance value of the energy receiving coil in the secondary-side energy receiver, the topology and inductance / capacitance values ​​of the compensation network of the primary-side energy transmitter are consistent with the topology and inductance / capacitance values ​​of the compensation network of the secondary-side energy receiver, and both the power converter of the primary-side energy transmitter and the power converter of the secondary-side energy transmitter use fully controlled switching devices to enable the wireless charging device to achieve bidirectional energy flow.

4. The wireless charging device according to claim 3, wherein the primary-side compensation network and the secondary-side compensation network are in a CLC-CLC or LCC-LCC symmetrical form, wherein, C represents the compensation capacitor, and L represents the compensation inductor.

5. The wireless charging device according to claim 3, wherein the inverter at the primary side energy transmitter or the rectifier at the secondary side energy receiver each comprises only one stage converter.

6. The wireless charging device according to claim 1, wherein the wireless charging device is configured to charge the load device through a constant current-constant voltage two-stage charging process. in, The first stage of the charging process is constant current charging. The operating frequency of the primary side energy transmitter is the constant current operating frequency. The secondary side power converter charges the load device with a constant current. In the first stage, the input current of the primary side compensation network will increase with the increase of the charging voltage of the secondary side power converter. The wireless charging device determines whether the input current has increased to the mode switching point. as well as, When the input current increases to the mode switching point, the operating frequency of the primary side energy transmitter switches from constant current operating frequency to constant voltage operating frequency, and the charging process of the wireless charging device enters the second stage. The second stage is constant voltage charging, which is performed at a constant voltage operating frequency. The charging voltage of the secondary side power converter remains constant, while the charging current of the primary side compensation network gradually decreases. The wireless charging device determines whether the input current of the primary side compensation network has decreased to the charging stop point. When the input current decreases to the charging stop point, the charging process ends.

7. The wireless charging device according to claim 6, wherein the mode switching point of the input current is associated with the battery characteristics of the load device and the impedance characteristics of the wireless charging device.

8. A wireless charging system, the wireless charging system comprising a wireless charging device according to any one of claims 1-6 and a control device, wherein the control device comprises an input voltage and current sampling circuit, a controller and a drive circuit, the controller comprising a charging parameter setting module and a mode switching module, the charging parameter setting module setting or pre-setting parameters for switching the operating frequency of the wireless charging device, including a constant current operating frequency, a constant voltage operating frequency, a mode switching point and a charging stop point, and the mode switching module switching the charging mode of the wireless charging device from a constant current charging mode to a constant voltage charging mode based on the mode switching point and the charging stop point.

9. A charging method for a wireless charging device, the charging method charging the load device through a constant current-constant voltage two-stage charging process, the charging method comprising: (1) The first stage of the charging process is constant current charging. The operating frequency of the primary side energy transmitter of the wireless charging device is the constant current operating frequency. The secondary side power converter of the wireless charging device charges the load device with a constant current. In the first stage, the input current of the primary side compensation network in the primary side energy transmitter will increase with the increase of the charging voltage of the secondary side power converter. In the first stage of the charging process, it is determined whether the input current increases to the mode switching point. as well as, (2) When the input current increases to the mode switching point, the operating frequency of the primary side energy transmitter switches from constant current operating frequency to constant voltage operating frequency, and the charging process of the wireless charging device enters the second stage. The second stage is constant voltage charging, which is performed at a constant voltage operating frequency. The charging voltage of the secondary side power converter remains constant, while the charging current of the primary side compensation network gradually decreases. In the second stage of the charging process, it is determined whether the input current of the primary side compensation network has dropped to the charging stop point. When the input current drops to the charging stop point, the charging process ends.

10. The charging method according to claim 9, wherein, The mode switching point of the input current is related to the battery characteristics and the impedance characteristics of the wireless charging device, and the mode switching point and the charging stop point are determined by the following steps: The parameters X of each compensation element in the primary-side compensation network and the secondary-side compensation network of the wireless charging device are... t1 To X t4 X r1 To X r4 The values ​​of mutual inductance M and the resistance R of the load device are input into the following formulas (1), (2), (3), and (4) to solve for parameters A and B: The current gain of the wireless charging device relative to the input voltage of the primary-side compensation network is expressed by formula (1): In formula (1), X = -jω cc MX t3 X r3 , Y1=(ω cc M) 2 (X t3 +X t4 )[jR-(X r3 +X r4 )], Y2=[(X t1 +X t2 )(X t3 +X t4 )+X t3 X t4 ], Y3=[j(X r1 +X r2 +X r3 )R-(X r1 +X r2 )(X r3 +X r4 )-X r3 X r4 ], M represents the mutual inductance between the primary and secondary energy emitting coils. R represents the resistance of the load device. Among them, jX ti (i = 2, 3, 4) represent the compensation elements L1, C1, C2, and C3 of the primary compensation network. t The impedance form, jX ri (i = 2, 3, 4) represents the compensation element C of the secondary side compensation network. r The impedance forms of C2 and L2, and the compensation elements in the primary and secondary compensation networks are arranged in a T-type equivalent network form, jX t1 and jX r1 Let i represent the impedances of the primary and secondary energy transmitting coils of the wireless charging device, respectively, and define the index i∈{1,2,3,4}: The simplified form of formula (1) is: The voltage gain of the wireless charging device relative to the input voltage is expressed by formula (3): In formula (3), X = -jω cv MX t3 X r3 R, Y4=(ω cv M) 2 (X t3 +X t4 )[jR-(X r3 +X r4 )], Y5=[(X t1 +X t2 )(X t3 +X t4 )+X t3 X t4 ], Y6=[j(X r1 +X r2 +X r3 )R-(X r1 +X r2 )(X r3 +X r4 )-X r3 X r4 ], The simplified form of formula (3) is: Solve for the constant current operating frequency, which makes |B / A| in formula (2) take the minimum value; solve for the constant voltage operating frequency, which makes |A / R| / |B / R| in formula (4) take the minimum value, thereby determining the constant current operating frequency and the constant voltage operating frequency respectively; Then, based on the battery characteristics of the load device, the optimal switching load for constant current charging mode and constant voltage charging mode is determined, and the input current of the primary-side energy emitter corresponding to this switching load is marked as the mode switching point for constant current charging and constant voltage charging; and The equivalent load at which the battery is fully charged is determined based on the battery characteristics, and the input current at the primary side energy emitter corresponding to the equivalent load is marked as the charging stop point.

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