A control method of current resonance

Abstract

The present application relates to the technical field of resonant circuit control, and provides a current resonance control method, which comprises: collecting a real-time current phase signal φ; and adjusting the inverter output frequency according to the real-time current phase signal φ to control the current resonance. The current resonance control method of the present application dynamically adjusts the inverter output frequency by monitoring the real-time current phase signal φ, prevents the system from falling into an undesirable resonance region, thereby reducing overcurrent or overvoltage caused by resonance, prolonging the service life of power devices, and reducing reactive power and loss.

Description

Technical Field

[0001] This invention relates to the field of resonant circuit control technology, and more specifically, to a method for controlling current resonance. Background Technology

[0002] In a circuit with an inductor and a capacitor connected in parallel, when the capacitance value makes the voltage and current in the circuit out of phase, meaning all the electrical energy from the power source is consumed by the resistor, creating a resistive circuit, this is called parallel resonance. Parallel resonance is a complete compensation; the power source does not need to provide reactive power, only the active power required by the resistor. At resonance, the total current in the circuit is at its minimum, while the current in a branch is often greater than the total current in the circuit; therefore, parallel resonance is also called current resonance.

[0003] If current resonance becomes uncontrolled, it can generate extremely high current or voltage amplitudes near the resonant frequency, leading to problems such as component damage, insulation breakdown, and thermal runaway. For example, in a series resonant circuit, the current at the resonant point may be much greater than the input current. If not limited, this can easily cause the inductor coil to overheat and burn out the equipment. Currently, current resonance is mainly controlled by adding capacitance to ground. However, this can only suppress specific frequency ranges. When the inductor and capacitor are affected by temperature and aging, the resonance conditions will change, resulting in a worse suppression effect.

[0004] Therefore, there is an urgent need to provide a control method for current resonance with better control effect. Summary of the Invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems.

[0006] This invention provides a method for controlling current resonance, comprising: acquiring a real-time current phase signal φ; and adjusting the inverter output frequency according to the real-time current phase signal φ to control current resonance.

[0007] In any of the above technical features, controlling current resonance by adjusting the inverter output frequency according to the real-time current phase signal φ includes: obtaining the real-time load impedance X according to the real-time current phase signal φ; and controlling the inverter output frequency according to the real-time load impedance X to control current resonance.

[0008] In any of the above technical features, controlling current resonance by adjusting the inverter output frequency according to the load impedance X includes: comparing the real-time load impedance X with a load impedance set threshold X. 阈 The comparison is performed, and the current resonance is judged to be abnormal based on the comparison results; the inverter output frequency is adjusted according to the judgment results to control the current resonance.

[0009] In any of the above technical features, determining whether the current resonance is abnormal based on the comparison result includes: if the real-time load impedance X is less than the load impedance set threshold X 阈If the current resonance is normal, then the current resonance is normal; if the real-time load impedance X is greater than the set load impedance threshold X... 阈 This indicates that there is an anomaly in the current resonance.

[0010] If an abnormality exists in the current resonance of any of the above technical features, the current resonance is controlled to migrate towards the suboptimal resonance point according to the impedance-frequency characteristic curve library.

[0011] In any of the above technical features, if there is no abnormality in the current resonance, the real-time temperature T is detected; the current resonance is controlled according to the real-time temperature T.

[0012] In any of the above technical features, controlling the current resonance based on the real-time temperature T includes: comparing the real-time temperature T with a first temperature threshold T1 and a second temperature threshold T2; controlling the current resonance based on the comparison result; wherein the first temperature threshold T1 is less than the second temperature threshold T2.

[0013] In any of the above technical features, controlling the current resonance based on the comparison result includes: if the real-time temperature T is less than the first temperature threshold T1, the current resonance remains unchanged; if the real-time temperature T is greater than the first temperature threshold T1 and less than the second temperature threshold T2, the inverter output frequency is adjusted to correct the current resonance; if the real-time temperature T is greater than the second temperature threshold T2, the inverter output frequency is adjusted to decrease.

[0014] In any of the above technical features, the phase signal φ is processed using a dual filtering mechanism, including: eliminating high-frequency harmonic interference through an FIR filter and tracking the fundamental phase using an adaptive Kalman filter; wherein, the noise covariance matrix of the adaptive Kalman filter is dynamically adjusted according to the real-time current distortion rate.

[0015] By adopting the technical solution of the present invention, the following technical effects can be achieved:

[0016] 1. The current resonance control method of the present invention dynamically adjusts the inverter output frequency by monitoring the real-time current phase signal φ, preventing the system from falling into the bad resonance region, thereby reducing overcurrent or overvoltage caused by resonance, extending the life of power devices, and reducing reactive power and losses.

[0017] 2. By acquiring the current phase signal φ in real time, the real-time load impedance X can be obtained. By accurately identifying the impedance change trend, the system can adjust the frequency in advance near the potential resonance point, so that the system operating frequency is close to the ideal resonance point, thereby minimizing energy reflection, improving coupling efficiency, achieving higher energy utilization, and effectively suppressing overcurrent and overvoltage caused by resonance, thereby preventing problems such as device overheating and insulation breakdown, and significantly improving the reliability of system operation.

[0018] 3. When the system current resonance is in a normal state, the temperature T of the working environment or key components is continuously monitored, and the control strategy is dynamically adjusted based on temperature changes to further optimize the system's operating performance and ensure that the stability of the resonance state and the energy efficiency level do not deviate due to temperature rise. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the current resonance control method according to an embodiment of the present invention. Detailed Implementation

[0020] To make the above-mentioned objectives, features, and advantages of the present invention more apparent and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In related technologies, to prevent uncontrolled current resonance from generating extremely high current or voltage amplitudes near the resonant frequency, which could lead to problems such as component damage, insulation breakdown, and thermal runaway, the common approach is to increase the capacitance to ground to control current resonance. However, this can only suppress specific frequency ranges. When the inductor and capacitor are affected by temperature and aging, the resonance conditions will change, resulting in a worse suppression effect.

[0022] In view of this, the present invention provides a current resonance control method, which controls the current resonance by adjusting the inverter output frequency through the real-time current phase signal φ, thereby achieving better control effect.

[0023] Specifically, embodiments of the present invention provide a current resonance control method, comprising: acquiring a real-time current phase signal φ; and adjusting the inverter output frequency according to the real-time current phase signal φ to control the current resonance.

[0024] Preferably, the real-time current phase signal φ refers to the real-time phase difference between the current and voltage in a power electronics or AC system. It represents the degree to which the current waveform "lags" or "leads" the voltage waveform. During parallel resonance, the current may rise sharply, and the real-time current phase signal φ may change drastically. By monitoring the real-time current phase signal φ, the inverter output frequency can be dynamically adjusted to prevent the system from falling into the undesirable resonance region, thereby reducing overcurrent or overvoltage caused by resonance, extending the life of power devices, and reducing reactive power and losses.

[0025] Preferably, since the resonant frequency is a physical characteristic of the system under fixed conditions, if the inverter output frequency is close to the resonant frequency, it is easy to induce strong resonance. The real-time current phase signal φ can be used as an important basis for judging whether it is close to the resonant point. Therefore, by adjusting the inverter output frequency so that the inverter output frequency is not equal to the resonant frequency, the dangerous area of ​​sharp current amplitude rise can be avoided, and the purpose of controlling resonance can be achieved.

[0026] In some embodiments of the present invention, adjusting the inverter output frequency according to the real-time current phase signal φ to control current resonance includes: obtaining the real-time load impedance X according to the real-time current phase signal φ; and controlling the inverter output frequency according to the real-time load impedance X to control current resonance.

[0027] Preferably, the method of the present invention is based on real-time phase monitoring to calculate load impedance, which can quickly respond to changes in system load or environmental conditions and dynamically adjust the inverter output frequency to ensure that the system operates within a safe frequency range, actively matching the target frequency to improve efficiency and effectively preventing the system from entering a dangerous resonance state. By acquiring the current phase signal φ in real time, the real-time load impedance X can be obtained. By accurately identifying the impedance change trend, the system can adjust the frequency in advance near the potential resonance point, making the system operating frequency close to the ideal resonance point, thereby minimizing energy reflection, improving coupling efficiency, achieving higher energy utilization, and effectively suppressing overcurrent and overvoltage caused by resonance, thereby preventing problems such as device overheating and insulation breakdown, and significantly improving the reliability of system operation. Furthermore, in the method of the present invention, all control is based on measurement and software logic analysis, without the need to add physical compensation devices such as reactors or filters, reducing system complexity and cost, and making it suitable for embedded system integration.

[0028] In some embodiments of the present invention, controlling current resonance by adjusting the inverter output frequency according to the load impedance X includes: comparing the real-time load impedance X with a load impedance set threshold X. 阈 The comparison is performed, and the current resonance is judged to be abnormal based on the comparison results; the inverter output frequency is adjusted according to the judgment results to control the current resonance.

[0029] Preferably, by continuously acquiring the load impedance X, the resonance trigger signal caused by system impedance anomalies can be quickly captured, and the real-time load impedance X can be compared with the load impedance set threshold X. 阈 By comparing the two, it is possible to quickly determine whether there is a sudden surge in current due to a sharp increase in impedance in parallel resonance, and whether there is a situation of system overheating or decreased energy coupling efficiency due to extremely high impedance in series resonance. This allows the control method of the present invention to meet the complex operating conditions of dynamic impedance characteristics under multi-source parallel and multi-load conditions, and to prevent faults such as overcurrent, overheating, and inverter tube failure caused by current resonance. Furthermore, the control method of the present invention can achieve accurate identification and avoid misjudgment due to general load disturbances.

[0030] In some embodiments of the present invention, determining whether the current resonance is abnormal based on the comparison result includes: if the real-time load impedance X is less than a set load impedance threshold X... 阈 If the current resonance is normal, then the current resonance is normal; if the real-time load impedance X is greater than the set load impedance threshold X... 阈 This indicates that there is an anomaly in the current resonance.

[0031] Preferably, the control method of the present invention obtains the real-time load impedance X and compares it with a set load impedance threshold X. 阈 By comparing the current impedance, it is possible to accurately determine whether the current resonance state is abnormal. When the real-time load impedance X is detected to be greater than the set load impedance threshold X, this will be detected. 阈 When the system detects an abnormal resonance state, it can immediately determine this and adjust the inverter's output frequency accordingly, effectively preventing resonance point excitation, overcurrent, overvoltage, and other faults, and improving the system's operational safety and stability. When the real-time load impedance X is less than the set load impedance threshold X... 阈 When the system determines that the resonance is normal, no frequency adjustment intervention is required, which is conducive to maintaining the efficient working state of the system. Furthermore, the control method of the present invention has the advantages of strong real-time performance, fast response speed, and simple control strategy. It can achieve dynamic adaptive adjustment under varying load conditions, significantly reduce the failure rate of the system under resonance conditions, improve energy transmission efficiency and power quality, enhance the environmental adaptability of the system, and has high practical value.

[0032] Furthermore, in parallel resonance, to avoid an abnormal increase in total impedance that would prevent the system from outputting current, a load impedance threshold X is set. 阈 It should be slightly less than the maximum impedance value when the system is in parallel resonance. At this time, the detected real-time load impedance X is greater than the load impedance set threshold X. 阈 When this occurs, it is determined that there is an anomaly in the current resonance. In series resonance, to prevent the system from entering the resonance point and to prevent excessive current, a load impedance threshold X is set. 阈 It should be slightly greater than the minimum impedance value at the resonant point. At this point, the detected real-time load impedance X is greater than the load impedance set threshold X. 阈 At that time, it was determined that there was an abnormality in the current resonance.

[0033] It should be noted that if the detected real-time load impedance X equals the load impedance set threshold X, 阈 The existence of current resonance should be determined based on the actual situation, and no specific limitations are made here.

[0034] In some embodiments of the present invention, if an anomaly exists in the current resonance, the current resonance is controlled to migrate towards the suboptimal resonance point according to the impedance-frequency characteristic curve library.

[0035] Preferably, the control method of the present invention, by constructing an impedance-frequency characteristic curve library and combining it with real-time acquired impedance data, can quickly locate a suboptimal resonant point closer to the safe operating range when the current impedance exceeds a preset threshold, indicating a resonance anomaly. This suboptimal resonant point typically has a lower resonant current peak or a wider frequency tolerance band, effectively reducing the risk of overcurrent and overvoltage and preventing device damage. Furthermore, compared to the traditional strategy of moving away from the resonant point, this method, by migrating to a suboptimal point, avoids overstressing the main resonant point while still keeping the system operating near the resonant region, thereby maintaining high power transmission efficiency or output power and avoiding a significant decrease in system efficiency due to excessive frequency drift. It is particularly suitable for applications requiring high efficiency and stability, such as LLC resonant converters, wireless charging for electric vehicles, and photovoltaic grid-connected inverter systems.

[0036] Furthermore, since the selection of the suboptimal resonant point is based on the established impedance-frequency characteristic curve library, the system can achieve adaptive adjustment under different load conditions, temperature changes, power grid disturbances and other factors, and has good dynamic response capability. At the same time, the impedance-frequency characteristic curves used can be constructed based on simulation and measured data, and have the characteristics of strong versatility and high portability.

[0037] In some embodiments of the present invention, if there is no abnormality in the current resonance, the real-time temperature T is detected; and the current resonance is controlled according to the real-time temperature T.

[0038] Preferably, the control method of the present invention, when the system current resonance is in a normal state, continuously monitors the temperature T of the working environment or key components, and dynamically adjusts the control strategy based on temperature changes to further optimize the system's operating performance, ensuring that the stability of the resonance state and the energy efficiency level do not deviate due to temperature rise. Since temperature changes can cause deviations in the actual values ​​of key parameters in the resonant network, such as inductance and capacitance, resulting in resonant frequency drift, and consequently affecting the phase matching and energy transfer efficiency of the current resonance, real-time temperature detection combined with a preset temperature-parameter mapping relationship can dynamically compensate for the inverter control frequency, modulation method, or resonant parameters, ensuring that the system continuously operates at the optimal or suboptimal resonance point and avoiding performance degradation. Furthermore, by further employing temperature-assisted control, the energy efficiency and long-term stability of the resonant network can be significantly improved, avoiding resonance deviation and efficiency degradation caused by high temperatures, while reducing thermal stress on power devices, extending device lifespan, and enhancing the overall system's operational reliability.

[0039] Furthermore, the control method of the present invention has predictive regulation capability, that is, before the resonance becomes abnormal, it can predict the possible parameter changes caused by temperature trends in advance and actively correct the control command to achieve feedforward stable control. This temperature-driven dynamic adjustment effectively improves the system's adaptability to environmental changes and is particularly suitable for scenarios with large day-night temperature differences or significant periodic load fluctuations, such as photovoltaic power generation, wireless charging of electric vehicles, LLC resonant converters and other systems.

[0040] In some embodiments of the present invention, controlling the current resonance based on the real-time temperature T includes: comparing the real-time temperature T with a first temperature threshold T1 and a second temperature threshold T2; controlling the current resonance based on the comparison result; wherein the first temperature threshold T1 is less than the second temperature threshold T2.

[0041] Preferably, the control method of the present invention dynamically monitors the real-time temperature T by setting a first temperature threshold T1 and a second temperature threshold T2, and adjusts the system's resonance control strategy based on the comparison result between T and the threshold. Compensation is intervened in the early stage of temperature rise to delay the occurrence of high temperature, avoid frequent triggering of protection shutdown, improve the continuous operation time of the system, and prevent overheating from causing damage, breakdown or aging of key components. It is especially suitable for high-frequency, high-density power conversion systems. Furthermore, the resonance parameters are corrected in a timely manner through temperature feedback to avoid resonance frequency deviation caused by device thermal drift, which can improve the long-term stability and control accuracy of the current resonance system. While ensuring the stability of the resonance system, the system's energy efficiency and safety are improved.

[0042] Preferably, since different temperature points represent different operating states, setting the first temperature threshold T1 to be less than the second temperature threshold T2 ensures that the system has a chance to mitigate the temperature rise before taking protective measures, rather than triggering protection as soon as the temperature rises, which could cause a significant performance degradation. The first temperature threshold T1 is usually set as the performance inflection point. After exceeding the first temperature threshold T1, parameters such as the on-resistance, capacitance, and inductance permeability of the device begin to drift significantly, thus requiring early intervention control. The second temperature threshold T2 is usually set as the extreme safe temperature. Exceeding the second temperature threshold T2 may cause problems such as thermal breakdown, capacitor insulation collapse, and inductor core saturation failure, which are states that require immediate protection. By comparing the real-time temperature T with the first temperature threshold T1 and the second temperature threshold T2 and controlling the current resonance based on the comparison results, the system stability can be greatly improved, preventing false protection or hardware failures caused by delayed response.

[0043] In some embodiments of the present invention, controlling the current resonance based on the comparison result includes: if the real-time temperature T is less than a first temperature threshold T1, controlling the current resonance to remain unchanged; if the real-time temperature T is greater than the first temperature threshold T1 and the real-time temperature T is less than a second temperature threshold T2, adjusting the inverter output frequency to correct the current resonance; if the real-time temperature T is greater than the second temperature threshold T2, adjusting the inverter output frequency to decrease.

[0044] Preferably, temperature changes affect the parameters of components in the resonant circuit, such as inductors and capacitors, leading to a shift in the resonant frequency. By setting two temperature thresholds, a first temperature threshold T1 and a second temperature threshold T2, the system can take corresponding control measures within different temperature ranges. When the real-time temperature T is less than the first temperature threshold T1, the system is in normal operation and requires no adjustment, maintaining the optimal resonance state and ensuring efficient operation. When the real-time temperature T is greater than the first temperature threshold T1 but less than the second temperature threshold T2, the temperature tends to rise. If no adjustment is made, the resonant frequency may shift. In this case, by appropriately adjusting the inverter output frequency, the system can compensate for the temperature-induced resonant frequency shift, maintaining it close to the optimal operating point. This reduces energy loss, improves energy transmission efficiency, avoids a decrease in power factor due to frequency shift, and extends the equipment's lifespan. When the real-time temperature T is greater than the second temperature threshold T2, the temperature exceeds the safety threshold. The system actively reduces the inverter output frequency and power output to prevent further temperature rise and avoid performance degradation or damage caused by component overheating, which could affect the normal operation of other related equipment.

[0045] Furthermore, the first temperature threshold T1 is preferably set to 75-90℃, and the second temperature threshold T2 is preferably set to 105-120℃; the real-time temperature T is preferably detected by a temperature sensor.

[0046] It should be noted that if the real-time temperature T is detected to be equal to the first temperature threshold T1 or the second temperature threshold T2, those skilled in the art should determine what kind of adjustment needs to be made based on the actual situation, without making specific limitations here.

[0047] In some embodiments of the present invention, the phase signal φ is processed using a dual filtering mechanism, including: eliminating high-frequency harmonic interference through an FIR filter and tracking the fundamental phase using an adaptive Kalman filter; wherein the noise covariance matrix of the adaptive Kalman filter is dynamically adjusted according to the real-time current distortion rate.

[0048] Preferably, in the phase signal φ processing, a dual filtering mechanism consisting of an FIR filter and an adaptive Kalman filter is introduced, which can significantly improve the system's anti-interference capability and phase tracking accuracy under complex current waveforms. The FIR filter is mainly used to suppress high-frequency harmonic interference in the input signal. Its linear phase characteristic can effectively prevent signal distortion and ensure that the phase information of the filtered signal does not shift. This is particularly critical for systems with phase as the core parameter, especially in environments with non-ideal factors such as high-frequency noise, electromagnetic interference, or rising edge spikes. The adaptive Kalman filter further performs fine estimation and dynamic tracking of the FIR-filtered signal. The advantage of this filter is that it can dynamically adjust its internal parameters, especially the noise covariance matrix, according to the actual working state. By introducing the real-time current distortion rate as the adjustment basis, the system can adaptively sense changes in the external noise level and optimize the filter gain accordingly, so as to be able to extract the fundamental phase stably and accurately under different load, voltage, or temperature conditions.

[0049] Preferably, the dual filtering mechanism can filter out high-frequency interference and ensure signal purity on the one hand; on the other hand, it can achieve high-precision real-time tracking of the fundamental phase and has good adaptive capability, thereby significantly reducing the steady-state error of the system and making the dynamic response smoother. It is particularly suitable for application scenarios with high phase sensitivity requirements.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method of current resonance, characterized by, Comprise: Collecting real-time current phase signals ; According to the real-time current phase signal Adjusting the inverter output frequency to control current resonance; Specifically comprise: According to the real-time current phase signal, obtain real-time load impedance X; comparing the real-time load impedance X with a load impedance set threshold value X 阈 impedance set threshold value X 阈 impedance set threshold value X 阈 impedance set threshold value X 阈 impedance set threshold if the real-time load impedance X is less than the load impedance set threshold X 阈 , determining that the current resonance is not abnormal; if the real-time load impedance X is greater than the load impedance set threshold X 阈 , it is determined that the current resonance is abnormal; If the current resonance has an abnormality, according to an impedance-frequency characteristic curve library, control the current resonance to migrate to a suboptimal resonance point; If the current resonance has no abnormality, detect real-time temperature T; according to the real-time temperature T, control the current resonance.

2. The control method according to claim 1, characterized by, The control of the current resonance according to the real-time temperature T comprises: Compare the real-time temperature T with a first temperature threshold T1 and a second temperature threshold T2; According to the comparison result, control the current resonance; Wherein, the first temperature threshold T1 is less than the second temperature threshold T2.

3. The control method according to claim 2, characterized by, The control of the current resonance according to the comparison result comprises: If the real-time temperature T is less than the first temperature threshold T1, control the current resonance not to change; If the real-time temperature T is greater than the first temperature threshold T1 and less than the second temperature threshold T2, adjust the inverter output frequency to correct the current resonance; If the real-time temperature T is greater than the second temperature threshold T2, adjust the inverter output frequency to be smaller.

4. The control method according to claim 1, characterized by, The phase signal ϕ is processed by a double filtering mechanism, comprising: Eliminate high-frequency harmonic interference through a FIR filter, and track the fundamental wave phase by using an adaptive Kalman filter; Wherein, the noise covariance matrix of the adaptive Kalman filter is dynamically adjusted according to the real-time current distortion rate.

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