Charger power factor improvement method based on dynamic impedance matching
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN YONGXINNENG TECH
- Filing Date
- 2026-02-02
- Publication Date
- 2026-06-26
Smart Images
Figure CN121618652B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power supply system technology, and specifically to a method for improving the power factor of a charger based on dynamic impedance matching. Background Technology
[0002] Wireless charging technology is a contactless power transfer technology that utilizes the principle of electromagnetic induction and can be applied to the charging of electric vehicles. A wireless charging system mainly consists of a transmitting coil and a receiving coil. The transmitting coil is installed in the charging equipment on the ground, and the receiving coil is installed on the chassis of the electric vehicle. When the electric vehicle is parked in the charging position, the transmitting coil generates an alternating magnetic field, causing the receiving coil to acquire electrical energy through electromagnetic induction, thus achieving wireless charging.
[0003] A wireless charger is the core device for wireless charging, mainly composed of a power module, an inverter module, an impedance matching network, a transmitting coil, and a control system. The power module converts AC power from the grid into stable DC power. The inverter module inverts the DC power into high-frequency AC power. The transmitting coil converts the high-frequency electrical energy into an alternating magnetic field, transmitting the energy to the receiving side through spatial magnetic field coupling. The impedance matching network adjusts the impedance characteristics of the transmitting side, enabling the system to operate in a resonant state. It typically employs a series-series (SS) compensation topology, where both the transmitting and receiving sides use inductors and capacitors connected in series.
[0004] The power factor of a charger is an indicator of system energy conversion efficiency, defined as the ratio of active power to apparent power. A higher power factor indicates higher energy utilization and reduces reactive power demand on the grid, thus minimizing harmonic pollution. When the system operates at its resonant frequency, the reactance of the inductor and capacitor cancels each other out, resulting in a purely resistive system with a power factor of 1 and the highest energy transfer efficiency. However, in actual charging processes, variations in vehicle parking position and load can alter the chassis height and position, changing the relative positions of the transmitting and receiving coils. This causes the mutual inductance between the two coils to deviate from its nominal value. This change in mutual inductance causes the system's equivalent impedance to deviate from its resonant point, creating a phase difference between the system voltage and current, leading to a decrease in the charger's power factor.
[0005] Existing impedance matching methods typically use a fixed step size to adjust the capacitor value. When the detuning degree is small, over-adjustment can easily cause oscillations, while when the detuning degree is large, under-adjustment leads to slow convergence. Therefore, there is an urgent need for a charger power factor improvement method based on dynamic impedance matching to solve the technical problem of low power factor and low energy conversion efficiency caused by the inability of traditional methods to adapt to different detuning degrees due to the use of a fixed capacitor adjustment step size. Summary of the Invention
[0006] To address the technical problem that existing impedance matching methods for chargers cannot adapt to different degrees of detuning, resulting in low power factor and low energy conversion efficiency, the present invention aims to provide a power factor improvement method for chargers based on dynamic impedance matching. The specific technical solution adopted is as follows:
[0007] This invention provides a method for improving the power factor of a charger based on dynamic impedance matching, the method comprising:
[0008] Based on the voltage and current signals at the transmitter input terminal of the charger, determine the resistive and reactive components of the input impedance;
[0009] Based on the resistive and reactive components, an impedance detuning compensation factor is constructed to characterize the degree and direction of the charger's deviation from the resonant state.
[0010] Based on the impedance detuning compensation factor and the reference compensation capacitor value of the charger in the nominal resonance state, the target capacitor adjustment amount of the charger is determined.
[0011] The control state of the switched capacitor array is updated by adjusting the target capacitance value to adjust the capacitance value of the impedance matching network, so that the input impedance of the charger approaches pure resistance.
[0012] Further, determining the resistive and reactive components of the input impedance based on the voltage and current signals at the transmitter input terminal of the charger includes:
[0013] Determine the phase and amplitude relationships between the voltage and current signals at the transmitter input of the charger;
[0014] Using the phase relationship and the amplitude relationship, the resistive and reactive components of the input impedance are determined.
[0015] Further, determining the phase and amplitude relationship between the voltage and current signals at the transmitter input terminal of the charger includes:
[0016] The voltage and current signals at the transmitter input of the charger are both subjected to discrete Fourier transform to obtain the voltage fundamental and current fundamental waves, respectively.
[0017] Determine the phase relationship and amplitude relationship between the fundamental voltage wave and the fundamental current wave.
[0018] Furthermore, using the phase relationship and the amplitude relationship, the resistive and reactive components of the input impedance are determined, including:
[0019] By using the phase difference and amplitude ratio between the voltage and current signals, the resistive and reactive components of the input impedance are calculated respectively.
[0020] Furthermore, the impedance detuning compensation factor, which characterizes the degree and direction of the charger's deviation from the resonant state based on the resistive and reactive components, includes:
[0021] Using the resistance and reactance components, determine the normalized proportion of the reactance component in the total reactance characteristic quantity composed of the resistance and reactance components;
[0022] The normalized ratio is used as an impedance detuning compensation factor to characterize the degree and direction of the charger's deviation from the resonant state; wherein the reactance component includes positive and negative signs.
[0023] Further, determining the total group impedance characteristic quantity composed of the resistance component and the reactance component includes: taking the sum of the absolute values of the resistance component and the reactance component as the total group impedance characteristic quantity.
[0024] Further, determining the target capacitance adjustment of the charger based on the impedance detuning compensation factor and the reference compensation capacitance value of the charger in the nominal resonance state includes:
[0025] By combining the impedance detuning compensation factor, the reference compensation capacitor value of the charger in the nominal resonance state, and the adjustment sensitivity coefficient, the target capacitor adjustment amount of the charger is determined.
[0026] Furthermore, obtaining the sensitivity adjustment coefficient includes:
[0027] The adjustment sensitivity coefficient is determined by using the input resistance value of the charger in the nominal resonant state and the inductive reactance value of the charger's transmitting coil at the nominal operating frequency.
[0028] Furthermore, the step of updating the control state of the switched capacitor array using the target capacitance adjustment to adjust the capacitance value of the impedance matching network includes:
[0029] The target capacitor adjustment amount is used to determine which capacitors need to be added or removed from the switched capacitor array, so as to update the control state of the switched capacitor array.
[0030] The updated control state of the switched capacitor array is used to close or open the corresponding electronic switches in the switched capacitor array in order to adjust the capacitance value of the impedance matching network.
[0031] Furthermore, determining which capacitors need to be added or removed from the switched capacitor array using the target capacitance adjustment includes:
[0032] Determine the unit capacitance value and the current capacitance level of the binary weighted capacitor, and update the current capacitance level using the target capacitance adjustment and the unit capacitance value to obtain the updated capacitance level.
[0033] Convert the updated capacitor series to binary representation to determine the binary weighted capacitors that need to be added or removed from the switched capacitor array.
[0034] The switched capacitor array consists of a base capacitor and multiple binary weighted capacitors. Each binary weighted capacitor is connected in series with an electronic switch and then in parallel with the base capacitor.
[0035] The present invention has the following beneficial effects:
[0036] This invention constructs an impedance detuning compensation factor, comprehensively analyzing the resistive and reactive components of the input impedance to reflect the magnitude and direction of system detuning. Compared to directly using the reactive component as the adjustment basis, this index eliminates dimensional differences between systems of different power levels through normalization, making it applicable to various wireless charging systems. By establishing a proportional relationship between the capacitance adjustment and the detuning compensation factor, adaptive matching between the adjustment amplitude and the degree of detuning is achieved. When detuning is severe, the adjustment amount increases, quickly compensating for large impedance shifts and shortening the time required for the system to return to resonance. When detuning is slight, the adjustment amount decreases, avoiding over-adjustment that could cause system oscillations and improving the stability of the adjustment process. Compared to traditional fixed-step adjustment methods, the adaptive adjustment strategy achieves better adjustment results under different degrees of detuning, balancing adjustment speed and stability, thereby significantly improving the power factor and energy conversion efficiency of the charger. Attached Figure Description
[0037] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0038] Figure 1 The flowchart illustrates the steps of a method for improving the power factor of a charger based on dynamic impedance matching, as provided in one embodiment of the present invention.
[0039] Figure 2 This is a detailed flowchart of step S1 in a charger power factor improvement method based on dynamic impedance matching, provided in an embodiment of the present invention.
[0040] Figure 3 This is a detailed flowchart of step S2 in a charger power factor improvement method based on dynamic impedance matching, provided in an embodiment of the present invention.
[0041] Figure 4This is a detailed flowchart of step S4 in a charger power factor improvement method based on dynamic impedance matching, provided in an embodiment of the present invention.
[0042] Figure 5 This is a schematic diagram of the hardware operating environment of the charger power factor improvement device based on dynamic impedance matching involved in the embodiment of the present invention. Detailed Implementation
[0043] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a charger power factor improvement method based on dynamic impedance matching proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.
[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0045] The following describes in detail, with reference to the accompanying drawings, a specific scheme for a charger power factor improvement method based on dynamic impedance matching provided by the present invention.
[0046] Example 1: For the charger power factor improvement method based on dynamic impedance matching provided by this invention, please refer to... Figure 1 The diagram illustrates a flowchart of a method for improving the power factor of a charger based on dynamic impedance matching, provided in an embodiment of the present invention.
[0047] The charger power factor improvement method based on dynamic impedance matching includes:
[0048] Step S1: Based on the voltage and current signals at the transmitter input terminal of the charger, determine the resistive and reactive components of the input impedance;
[0049] In a wireless charging system (in this embodiment, the charger is the primary device), the power factor depends on the nature of the input impedance on the transmitting side. Impedance is a complex number, comprising resistance (real part, representing energy consumption) and reactance (imaginary part, representing energy exchange). When the input impedance is purely resistive (inductive and capacitive reactance cancel each other out), the system is in resonance, with voltage and current in phase, and a power factor of 1. When the input impedance includes a reactive component, the system is detuned, with a phase difference between voltage and current, and a power factor less than 1. To achieve adaptive dynamic impedance matching, an index reflecting the degree and direction of system detuning needs to be constructed for subsequent capacitor adjustment.
[0050] First, the voltage and current signals at the input terminal of the transmitter are acquired. The voltage signal is acquired from the inverter output terminal through a voltage transformer or a voltage divider resistor network, and the current signal is acquired from the transmitter circuit through a current transformer or a Hall sensor. The acquired analog signals are conditioned and then sent to a dual-channel ADC (Analog-to-Digital Converter) for synchronous sampling at a sampling frequency of 1 MHz.
[0051] Then, the resistive component of the input impedance is calculated based on the voltage and current signals. and reactance component .
[0052] Specifically, please refer to Figure 2 Step S1 includes:
[0053] Step S11: Determine the phase relationship and amplitude relationship between the voltage signal and the current signal at the transmitter input terminal of the charger;
[0054] More specifically, step S11 includes:
[0055] The voltage and current signals at the transmitter input of the charger are both subjected to discrete Fourier transform to obtain the voltage fundamental and current fundamental waves, respectively.
[0056] Determine the phase relationship and amplitude relationship between the fundamental voltage wave and the fundamental current wave.
[0057] Step S12: Using the phase relationship and the amplitude relationship, determine the resistance component and reactance component of the input impedance.
[0058] More specifically, step S12 includes:
[0059] By using the phase difference and amplitude ratio between the voltage and current signals, the resistive and reactive components of the input impedance are calculated respectively.
[0060] In this embodiment, in a real wireless charging system, due to the switching action of the inverter and the nonlinearity of the circuit, the collected voltage and current signals often contain high-order harmonic components and random noise. Therefore, this embodiment can use a fundamental frequency extraction method based on Discrete Fourier Transform (DFT) to extract the amplitude and phase information of the fundamental frequency component from the signal containing harmonics and noise.
[0061] Based on voltage and current signal sequences, the impedance component is calculated in each window using Discrete Fourier Transform (DFT). The DFT window length can be set to 10 cycles at the system operating frequency (e.g., 85kHz), with a sampling frequency of 1MHz, corresponding to 118 sampling points. After obtaining the complex representations of the fundamental voltage and current signals, their magnitudes are calculated to obtain the amplitude of the fundamental voltage signal. and the amplitude of the fundamental current wave Then, calculate their arguments to obtain the fundamental voltage phase. Phase with the fundamental current The current lags behind the voltage by the phase difference. It should be noted that, because the phase difference is a periodic subtraction, therefore, in When, then the phase difference value ,exist At that time, This allows for the calculation of the phase difference across different periods, thus determining the magnitude of the input impedance. It is the ratio of the voltage fundamental amplitude to the current fundamental amplitude, i.e. (It should be noted that when the current amplitude is less than the preset amplitude threshold, such as less than 0.05A, no adjustment is made, that is...) Based on the polar and rectangular coordinate transformation relationship of complex impedance, the resistive component of the input impedance is: The reactance component is .
[0062] The resistive component represents the portion of active power consumed in a circuit, converting electrical energy into heat. The reactive component represents the impedance generated by energy storage elements in a circuit, representing the energy exchange between inductors and capacitors and the AC power source without consuming energy. When When the input impedance is inductive, it means the inductive reactance is greater than the capacitive reactance, and the current lags behind the voltage; when When the input impedance is capacitive, it means the capacitive reactance is greater than the inductive reactance, and the current leads the voltage; when When the input impedance is purely resistive, the voltage and current are in phase, the system is in a resonant state, and the power factor is equal to 1.
[0063] Step S2: Based on the resistance and reactance components, construct an impedance detuning compensation factor that characterizes the degree and direction of the charger's deviation from the resonant state.
[0064] In wireless charging systems, there is mutual inductance coupling between the transmitting and receiving coils. The mutual inductance value depends on the relative position and distance between the two coils. When the vehicle's parking position shifts or the chassis height changes due to load variations, the mutual inductance value will deviate from the design value. According to circuit theory, the load on the receiving side will generate a reflected impedance on the transmitting side through mutual inductance coupling. The magnitude of the reflected impedance is proportional to the square of the mutual inductance value. For the real part of the impedance, the change in reflected resistance mainly affects the amount of active power transmitted to the load, but does not affect the power factor. For the imaginary part of the impedance, the reflected reactance is directly superimposed on the compensation network on the transmitting side, changing the reactance component of the input impedance on the transmitting side. Therefore, changes in mutual inductance lead to changes in reflected impedance, which in turn affects the reactance component of the input impedance on the transmitting side. Different degrees of mutual inductance deviation will result in different magnitudes of the reactance component; the greater the deviation, the greater the reactance component. The larger.
[0065] When changes in mutual inductance lead to an increase in reflected reactance, this causes a reactance component in the input impedance on the transmitting side. When the input impedance deviates from zero, the capacitive reactance can be adjusted by changing the capacitance value of the compensation capacitor on the transmitting side. When the input impedance is inductively detuned, the capacitance is decreased to increase the capacitive reactance, thereby offsetting the inductive reflected reactance; when the input impedance is capacitively detuned, the capacitance is increased to decrease the capacitive reactance, thereby compensating for the capacitive reflected reactance. This compensates for the reactive component introduced on the transmitting side due to changes in mutual inductance, making the system's input impedance approach purely resistive.
[0066] Specifically, please refer to Figure 3 Step S2 includes:
[0067] Step S21: Using the resistance component and the reactance component, determine the normalized proportion of the reactance component in the total reactance characteristic quantity composed of the resistance component and the reactance component.
[0068] Step S22: The normalized ratio is used as an impedance detuning compensation factor characterizing the degree and direction of the charger's deviation from the resonant state; wherein the reactance component includes positive and negative signs.
[0069] In this embodiment, due to the reactance component Wireless charging systems, which have ohmic dimensions, exhibit vastly different absolute reactance values across different power levels. For instance, a kilowatt-level system might have a reactance of a few ohms, while a megawatt-level system could have a reactance of tens of ohms. This makes it difficult to handle using a uniform threshold and adjustment strategy. Furthermore, directly adjusting the reactance value requires setting the adjustment step size based on specific system parameters, increasing system complexity. Therefore, this embodiment constructs an impedance mistuning compensation factor. The reactance component is normalized to the range of (-1, 1) so that the index can uniformly describe the degree of detuning under different systems and operating conditions, which facilitates subsequent adaptive adjustment strategies. The formula is:
[0070] in, This represents the impedance detuning compensation factor, which is dimensionless and has a value range of (-1, 1). The reactance component of the input impedance is expressed in ohms (Ω). The resistive component of the input impedance, measured in ohms (Ω), under normal operating conditions. ,exist and When all values are 0 (equipment failure), the system will directly report an error and stop the subsequent processing.
[0071] The principle behind this formula is as follows: This index is the normalized proportion of the reactance component in the total impedance characteristic quantity, while retaining the positive or negative sign of the reactance to indicate the direction of detuning. The denominator is the sum of the absolute values of the resistive and reactance components of the input impedance, representing a characteristic quantity characterizing the overall impedance properties. When the system is in a resonant state, ,therefore This indicates that no adjustment is needed; when the system is inductively detuned, ,therefore And the more severe the detuning ( The larger ( The closer it is to 1, the more capacitively detuned the system becomes. ,therefore And the more severe the detuning ( The larger ( The closer to -1; The magnitude of the value reflects the severity of the detuning. The positive or negative sign reflects the direction of the mistuning.
[0072] The reason for using As a normalization reference, rather than the impedance magnitude .First, First, this avoids square root operations, reducing the complexity of real-time calculations; second, this form ensures... ,because Hengcheng (under normal working conditions) This avoids extreme situations. Third, this normalization method is applicable to numerical problems approaching infinity; When the value is relatively small (close to the resonance state) Approximate and A linear relationship exists. When the value is large (severe detuning) Approaching Saturation, this characteristic, is beneficial for the design of subsequent adjustment strategies.
[0073] The impedance mistuning compensation factor obtained through the above implementation process This reflects the degree and direction of the current system's deviation from the resonant state.
[0074] Step S3: Based on the impedance detuning compensation factor and the reference compensation capacitor value of the charger in the nominal resonance state, determine the target capacitor adjustment amount of the charger.
[0075] After obtaining the impedance detuning compensation factor, it is necessary to determine the capacitor adjustment amount to compensate for the current detuning state. Traditional methods use fixed step size adjustment, which is difficult to adapt to different detuning degrees. When the detuning is severe, the compensation is too small, resulting in slow convergence; when the detuning is slight, the step size is too large, resulting in oscillation. This embodiment achieves adaptive matching between the adjustment amount and the degree of detuning by establishing a relationship between the capacitor adjustment amount and the impedance detuning compensation factor.
[0076] Specifically, step S3 includes:
[0077] By combining the impedance detuning compensation factor, the reference compensation capacitor value of the charger in the nominal resonance state, and the adjustment sensitivity coefficient, the target capacitor adjustment amount of the charger is determined.
[0078] The acquisition of the adjustment sensitivity coefficient includes:
[0079] The adjustment sensitivity coefficient is determined by using the input resistance value of the charger in the nominal resonant state and the inductive reactance value of the charger's transmitting coil at the nominal operating frequency.
[0080] Based on the above embodiments, in this embodiment, the capacitance adjustment amount should be proportional to the degree of detuning; the more severe the detuning (absolute value), the higher the coefficient of performance. The larger the adjustment amount, the more slight the detuning. The smaller the adjustment amount, the smaller it should be, thus ensuring the adaptability of the adjustment strategy. (Using the reference (compensation) capacitor...) As a benchmark for the adjustment amount, ensuring that the adjustment amount is within a reasonable range, the formula for calculating the (target) capacitor adjustment amount is:
[0081] in, This indicates the amount of capacitance adjustment, measured in farads (F). A positive value indicates an increase in capacitance, while a negative value indicates a decrease in capacitance. This represents the reference (compensation) capacitance value, measured in farads (F). It is the compensation capacitance value of the system under nominal resonance conditions and is an inherent parameter of the system.
[0082] The principle of this formula is: when At this time, the system exhibits inductive detuning, with inductive reactance exceeding capacitive reactance. This necessitates increasing the capacitive reactance to compensate, but increasing the capacitive reactance requires decreasing the capacitance (because capacitive reactance and capacitance are inversely proportional). Therefore... ;when At this time, the system exhibits capacitive detuning, with capacitive reactance exceeding inductive reactance. It is necessary to reduce the capacitive reactance to compensate, and reducing the capacitive reactance requires increasing the capacitance value. Therefore... The negative sign ensures the correct correspondence between the detuning direction and the tuning direction.
[0083] , representing the adjustment sensitivity coefficient, is dimensionless. Wherein, The input resistance value at the nominal resonant state is expressed in ohms (Ω). It is an inherent parameter of the system and is determined by measurement or calculation during the system design phase. Specifically, it can be a preset fixed empirical value or a system initialization calibration value. This indicates the inductive reactance of the transmitting coil at the nominal operating frequency. The unit is ohms (Ω), where Represents angular frequency. Indicates the operating frequency. The inductance of the transmitting coil represents the system's inherent parameters, and all are positive.
[0084] The principle behind this formula is as follows: the sensitivity adjustment coefficient is the ratio of the nominal input resistance to the sum of the nominal input resistance and the coil inductive reactance, reflecting the proportion of the resistive component in the system under nominal conditions. This coefficient adjusts the sensitivity of the capacitor regulation based on the inherent characteristics of the system. When the nominal input resistance of the system is relatively large compared to the coil inductive reactance, A larger nominal input resistance indicates that the system is more sensitive to changes in capacitance, requiring a larger adjustment amount; when the nominal input resistance is relatively small... A smaller value indicates that the system is not very sensitive to changes in capacitance, and the adjustment amount should be reduced accordingly. This design allows systems with different parameters to obtain a suitable adjustment response.
[0085] For capacitor adjustment This indicates the magnitude and direction of the capacitance adjustment needed in the current cycle. A positive value indicates that the compensation capacitor needs to be increased to reduce the capacitive reactance, while a negative value indicates that the compensation capacitor needs to be decreased to increase the capacitive reactance.
[0086] Step S4: Update the control state of the switched capacitor array using the target capacitance adjustment to adjust the capacitance value of the impedance matching network, so that the input impedance of the charger approaches pure resistance.
[0087] After obtaining the capacitance adjustment, the impedance matching network needs to be adjusted to improve the power factor. This is achieved by controlling the switching state of the switched capacitor array and updating the capacitance value of the impedance matching network according to the capacitance adjustment, so that the input impedance of the charger approaches pure resistance.
[0088] Specifically, please refer to Figure 4 Step S4, which updates the control state of the switched capacitor array using the target capacitance adjustment amount to adjust the capacitance value of the impedance matching network, includes:
[0089] Step S41: Use the target capacitor adjustment amount to determine which capacitors need to be added or removed from the switched capacitor array, so as to update the control state of the switched capacitor array.
[0090] More specifically, step S41, which uses the target capacitance adjustment amount to determine the capacitors that need to be added or removed from the switched capacitor array, includes:
[0091] The unit capacitance value and current capacitance level of the binary weighted capacitor are determined. The current capacitance level is updated using the target capacitance adjustment and the unit capacitance value to obtain the updated capacitance level. It should be noted that if the updated capacitance level touches a preset boundary (0 or the preset maximum value) and the detuning factor still exceeds the allowable range, an impedance mismatch alarm signal is generated, indicating that the environment exceeds the adjustment capability. Assuming the switched capacitor array consists of 8 binary weighted capacitors, the maximum value is... The default boundary is [0, 255].
[0092] Convert the updated capacitor series to binary representation to determine the binary weighted capacitors that need to be added or removed from the switched capacitor array.
[0093] The switched capacitor array consists of a base capacitor and multiple binary weighted capacitors. Each binary weighted capacitor is connected in series with an electronic switch and then in parallel with the base capacitor.
[0094] Step S42: Using the updated control state of the switched capacitor array, the corresponding electronic switches in the switched capacitor array are closed or opened to adjust the capacitance value of the impedance matching network.
[0095] Based on the above embodiments, in this embodiment, the switched capacitor array is a circuit structure that controls multiple fixed capacitors connected in parallel by electronic switches, enabling discrete adjustment of the capacitance value. In one embodiment, the basic capacitor... and It consists of several binary weighted capacitors. A base capacitor is fixedly connected in the circuit, providing the lower limit of the capacitance adjustment range. Each binary weighted capacitor is connected in series with an electronic switch, and then in parallel with the base capacitor. The electronic switch can be implemented using a metal-oxide-semiconductor field-effect transistor (MOSFET). The capacitance of each binary weighted capacitor is ,in The capacitance value is per unit. .
[0096] Current total capacitance of the impedance matching network It consists of the basic capacitor and the already connected binary weighted capacitors. Let the current capacitor level be... (That is, the total value of the currently connected binary weighted capacitors is) ),but The capacitor adjustment amount is When, the adjustment amount for calculating the capacitor stage is: .
[0097] in, This represents the amount of capacitor stage adjustment. It is a dimensionless integer. A positive value indicates that the capacitor connected is increased, and a negative value indicates that the capacitor connected is decreased. This represents the unit capacitance value, expressed in farads (F), and is the minimum adjustment step size of the switched capacitor array. This represents the rounding function.
[0098] Update capacitor stage to Boundary constraints are applied to the updated capacitor order. This ensures that the capacitor order is within the adjustable range of the array. Within the range, avoid exceeding the array's capacity.
[0099] Update the capacitor level Convert to binary representation to obtain the control state of each switch. Let... The binary representation of is Then the first The state of the switch .when At that time, the first When a switch is closed, the corresponding capacitor... Access circuit; when At that time, the first When a switch is open, the corresponding capacitor is not connected to the circuit.
[0100] Once the switch state is determined, a control signal is sent to each electronic switch via the control circuit to update the switch state. After the switch state is updated, the capacitance value of the impedance matching network changes. It should be noted that the zero-crossing signal of the voltage across the compensation capacitor on the transmitting side is detected, and the electronic switch is closed or opened at the moment the current crosses zero.
[0101] After adjusting the capacitance value, the sum of the compensation capacitor on the transmitting side and the reactance of the transmitting coil changes. This is due to the capacitance adjustment... It is based on the impedance mistuning compensation factor The adaptive calculation results in a large adjustment amount when detuning is severe, enabling rapid compensation; and a small adjustment amount when detuning is slight, avoiding over-adjustment and oscillation. Through periodic execution, the reactive component of the system input impedance gradually approaches zero, the input impedance approaches pure resistance, and the power factor gradually increases to near 1. In one embodiment, the execution period can be 100ms.
[0102] This invention constructs an impedance detuning compensation factor, comprehensively analyzing the resistive and reactive components of the input impedance to reflect the magnitude and direction of system detuning. Compared to directly using the reactive component as the adjustment basis, this index eliminates dimensional differences between systems of different power levels through normalization, making it applicable to various wireless charging systems. By establishing a proportional relationship between the capacitance adjustment and the detuning compensation factor, adaptive matching between the adjustment amplitude and the degree of detuning is achieved. When detuning is severe, the adjustment amount increases, quickly compensating for large impedance shifts and shortening the time required for the system to return to resonance. When detuning is slight, the adjustment amount decreases, avoiding over-adjustment that could cause system oscillations and improving the stability of the adjustment process. Compared to traditional fixed-step adjustment methods, the adaptive adjustment strategy achieves better adjustment results under different degrees of detuning, balancing adjustment speed and stability, thereby significantly improving the power factor and energy conversion efficiency of the charger.
[0103] Example 2:
[0104] This invention also proposes a charger power factor improvement device based on dynamic impedance matching. The device can be a wireless charging pile, a computer, a server, or a combination of multiple devices.
[0105] like Figure 5 As shown, Figure 5 This is a schematic diagram of the hardware operating environment of the charger power factor improvement device based on dynamic impedance matching involved in the embodiments of the present invention.
[0106] like Figure 5As shown, the charger power factor enhancement device based on dynamic impedance matching may include: a processor 1001, such as a CPU; a network interface 1004; a user interface 1003; a memory 1005; and a communication bus 1002. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display or an input unit such as a control panel; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface). The memory 1005 may be high-speed RAM or non-volatile memory, such as a disk drive. Optionally, the memory 1005 may also be a storage device independent of the aforementioned processor 1001. The memory 1005, as a computer storage medium, may include a charger power factor enhancement program based on dynamic impedance matching, referred to as the "charger power factor enhancement program."
[0107] Those skilled in the art will understand that Figure 5 The hardware structure shown does not constitute a limitation on the device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.
[0108] Continue to refer to Figure 5 , Figure 5 The memory 1005, which is a computer-readable storage medium, may include an operating device, a user interface module, a network communication module, and a charger power factor enhancement program based on dynamic impedance matching.
[0109] exist Figure 5 In this embodiment, the network communication module is mainly used to connect to the server and can communicate with the server for data; while the processor 1001 can call the charger power factor improvement program based on dynamic impedance matching stored in the memory 1005 and execute the steps in the above embodiments.
[0110] Based on the hardware structure of the charger power factor improvement device based on dynamic impedance matching described above, various embodiments of the charger power factor improvement method based on dynamic impedance matching of the present invention are implemented.
[0111] Furthermore, the present invention also provides a computer-readable storage medium. The computer-readable storage medium stores a charger power factor improvement program based on dynamic impedance matching, wherein when the charger power factor improvement program based on dynamic impedance matching is executed by a processor, it implements the steps of the charger power factor improvement method based on dynamic impedance matching as described above.
[0112] The method implemented when the charger power factor improvement program based on dynamic impedance matching is executed can be referred to in various embodiments of the charger power factor improvement method based on dynamic impedance matching of the present invention, and will not be repeated here.
[0113] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
[0114] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.
[0115] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0116] The above description is only a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. All equivalent structural / method transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the scope of protection of the present invention.
Claims
1. A method for improving the power factor of a charger based on dynamic impedance matching, characterized in that, The method includes the following steps: Based on the voltage and current signals at the transmitter input terminal of the charger, determine the resistive and reactive components of the input impedance; Based on the resistance and reactance components, an impedance detuning compensation factor is constructed to characterize the degree and direction of the charger's deviation from the resonant state. This includes: using the resistance and reactance components, determining the normalized proportion of the reactance component in the total group reactance characteristic quantity composed of the resistance and reactance components; using the normalized proportion as the impedance detuning compensation factor to characterize the degree and direction of the charger's deviation from the resonant state; wherein the reactance component includes positive and negative signs. Based on the impedance detuning compensation factor and the reference compensation capacitor value of the charger in the nominal resonance state, the target capacitor adjustment amount of the charger is determined, including: combining the impedance detuning compensation factor, the reference compensation capacitor value of the charger in the nominal resonance state and the adjustment sensitivity coefficient to determine the target capacitor adjustment amount of the charger. The control state of the switched capacitor array is updated by using the target capacitance adjustment to adjust the capacitance value of the impedance matching network, so that the input impedance of the charger approaches pure resistance. Determining the total group impedance characteristic quantity composed of the resistance component and the reactance component includes: taking the sum of the absolute values of the resistance component and the reactance component as the total group impedance characteristic quantity; The acquisition of the sensitivity adjustment coefficient includes: determining the sensitivity adjustment coefficient by using the input resistance value of the charger in the nominal resonant state and the inductive reactance value of the charger's transmitting coil at the nominal operating frequency.
2. The method for improving the power factor of a charger based on dynamic impedance matching according to claim 1, characterized in that, The determination of the resistive and reactive components of the input impedance based on the voltage and current signals at the transmitter input terminal of the charger includes: Determine the phase and amplitude relationships between the voltage and current signals at the transmitter input of the charger; Using the phase relationship and the amplitude relationship, the resistive and reactive components of the input impedance are determined.
3. The method for improving the power factor of a charger based on dynamic impedance matching according to claim 2, characterized in that, Determining the phase and amplitude relationships between the voltage and current signals at the transmitter input of the charger includes: The voltage and current signals at the transmitter input of the charger are both subjected to discrete Fourier transform to obtain the voltage fundamental and current fundamental waves, respectively. Determine the phase relationship and amplitude relationship between the fundamental voltage wave and the fundamental current wave.
4. The method for improving the power factor of a charger based on dynamic impedance matching according to claim 2, characterized in that, Using the phase relationship and the amplitude relationship, the resistive and reactive components of the input impedance are determined, including: By using the phase difference and amplitude ratio between the voltage and current signals, the resistive and reactive components of the input impedance are calculated respectively.
5. The method for improving the power factor of a charger based on dynamic impedance matching according to claim 1, characterized in that, The method of updating the control state of the switched capacitor array using the target capacitance adjustment to adjust the capacitance value of the impedance matching network includes: The target capacitor adjustment amount is used to determine which capacitors need to be added or removed from the switched capacitor array, so as to update the control state of the switched capacitor array. The updated control state of the switched capacitor array is used to close or open the corresponding electronic switches in the switched capacitor array in order to adjust the capacitance value of the impedance matching network.
6. The method for improving the power factor of a charger based on dynamic impedance matching according to claim 5, characterized in that, The method of determining which capacitors need to be added or removed from the switched capacitor array using the target capacitor adjustment amount includes: Determine the unit capacitance value and the current capacitance level of the binary weighted capacitor, and update the current capacitance level using the target capacitance adjustment and the unit capacitance value to obtain the updated capacitance level. Convert the updated capacitor series to binary representation to determine the binary weighted capacitors that need to be added or removed from the switched capacitor array. The switched capacitor array consists of a base capacitor and multiple binary weighted capacitors. Each binary weighted capacitor is connected in series with an electronic switch and then in parallel with the base capacitor.