Current resonance control method

Abstract

The invention relates to the technical field of resonance circuit control, and provides a current resonance control method, which comprises the following steps: acquiring a real-time current phase signal phi; and adjusting the output frequency of the inverter according to the real-time current phase signal phi to control the current resonance. According to the current resonance control method, the output frequency of the inverter is dynamically adjusted by monitoring the real-time current phase signal phi, and the system is prevented from falling into a poor resonance area, so that overcurrent or overvoltage caused by resonance is reduced, the service life of a power device is prolonged, and reactive power and loss are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of resonant circuit control, and more particularly, to a method for controlling current resonance. Background Art

[0002] In a circuit where an inductor and a capacitor are connected in parallel, when the capacitance is such that the voltage and current in the circuit are in the same phase, that is, all the electrical energy of the power supply is consumed by the resistor and it becomes a resistive circuit, it is called parallel resonance. Parallel resonance is a complete compensation, and the power supply only needs to provide the active power required by the resistor without providing reactive power. At resonance, the total current in the circuit is the smallest, while the current in the branch is often greater than the total current in the circuit. Therefore, parallel resonance is also called current resonance.

[0003] Once the current resonance is out of control, extremely high current or voltage amplitudes may be generated near the resonance frequency, which may lead to problems such as component damage, insulation breakdown, and thermal runaway. For example, in a series resonance circuit, the current at the resonance point may be much greater than the input current. If not restricted, it is easy to cause the inductor coil to overheat and burn out the equipment. Currently, the current resonance is mainly controlled by increasing the capacitance to the ground, but this can only suppress a specific frequency band. 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 method for controlling current resonance with a better control effect. Summary of the Invention

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

[0006] The present invention provides a method for controlling current resonance, including: collecting a real-time current phase signal φ; adjusting the output frequency of the inverter according to the real-time current phase signal φ to control the current resonance.

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

[0008] Among any of the above technical features, adjusting the output frequency of the inverter according to the load impedance X to control the current resonance includes: comparing the real-time load impedance X with a load impedance set threshold X 阈 and judging whether the current resonance is abnormal according to the comparison result; adjusting the output frequency of the inverter according to the judgment result to control the current resonance.

[0009] Among any of the above technical features, judging whether the current resonance is abnormal according to the comparison result includes: if the real-time load impedance X is less than the load impedance set threshold X 阈, it is determined that there is no abnormality in the current resonance; if the real-time load impedance X is greater than the set threshold X of the load impedance 阈 , it is determined that there is an abnormality in the current resonance.

[0010] In any of the above technical features, if there is an abnormality in the current resonance, according to the impedance-frequency characteristic curve library, the current resonance is controlled to migrate to the sub-optimal resonance point.

[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 according to the real-time temperature T includes: comparing the real-time temperature T with the first temperature threshold T1 and the second temperature threshold T2; controlling the current resonance according to 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 according to the comparison result includes: if the real-time temperature T is less than the first temperature threshold T1, controlling the current resonance not to change; if the real-time temperature T is greater than the first temperature threshold T1 and the real-time temperature T is less than the 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 become smaller.

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

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

[0016] 1. The control method of the current resonance 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 a bad resonance area, thereby reducing overcurrent or overvoltage caused by resonance, extending the life of power devices, and reducing reactive power and losses;

[0017] 2. By collecting 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 approach the ideal resonance point, thereby minimizing energy reflection, improving coupling efficiency, realizing higher energy utilization rate, and effectively suppressing overcurrent and overvoltage caused by resonance, thereby preventing problems such as device overheating and insulation breakdown, and significantly improving the operation reliability of the system;

[0018] 3. When the system current resonance is in a normal state, by continuously monitoring the temperature T of the working environment or key devices and dynamically adjusting the control strategy based on the temperature change, the system operation performance can be further optimized to ensure the stability of the resonance state and the energy efficiency level does not shift due to temperature rise. Description of the Drawings

[0019] Figure 1 Schematic diagram of the control method for current resonance according to an embodiment of the present invention. Detailed Embodiments

[0020] To make the above objects, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0021] In related technologies, to prevent the current resonance from being uncontrolled and generating extremely high current or voltage amplitudes near the resonance frequency, which may cause problems such as component damage, insulation breakdown, and thermal runaway, usually the method of increasing the capacitance to the ground is adopted to control the current resonance. However, this can only suppress a specific frequency band. When the inductance and capacitance 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 control method for current resonance, which controls the current resonance by adjusting the inverter output frequency through the real-time current phase signal φ, thereby obtaining a better control effect.

[0023] Specifically, an embodiment of the present invention provides a control method for current resonance, including: collecting the real-time current phase signal φ; 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 alternating current system, which represents the "lag" or "lead" degree of the current waveform relative to the voltage waveform. During parallel resonance, the current may rise sharply and the real-time current phase signal φ may change violently. By monitoring the real-time current phase signal φ, the inverter output frequency is dynamically adjusted to prevent the system from falling into a bad resonance area, thereby reducing the overcurrent or overvoltage caused by resonance, extending the life of power devices, and reducing reactive power and losses.

[0025] Preferably, since the resonant point frequency is a physical characteristic of the system under a fixed condition, if the inverter output frequency is close to the resonant point frequency, strong resonance is likely to be excited. 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 point frequency, the dangerous area where the current amplitude suddenly rises can be avoided, and the purpose of controlling resonance can be achieved.

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

[0027] Preferably, the method of the present invention calculates the load impedance based on real-time phase monitoring, can quickly respond to changes in system load or environmental conditions, and dynamically adjusts the inverter output frequency to ensure that the system operates within a safe frequency range and actively matches the target frequency to improve efficiency, and effectively avoids the system entering a dangerous resonance state; by real-time collecting the current phase signal φ, 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 approach the ideal resonance point, thereby minimizing energy reflection, improving coupling efficiency, achieving higher energy utilization rate, and effectively suppressing overcurrent and overvoltage caused by resonance, thus preventing problems such as device overheating and insulation breakdown, and significantly improving the system operation reliability; moreover, in the method of the present invention, all controls are realized based on measurement and software logic analysis, without adding physical compensation devices such as reactors or filters, etc., reducing the system complexity and cost, and being suitable for embedded system integration.

[0028] In some embodiments of the present invention, controlling the current resonance by adjusting the inverter output frequency according to the load impedance X includes: comparing the real-time load impedance X with the load impedance set threshold X 阈 and judging whether the current resonance is abnormal according to the comparison result; adjusting the inverter output frequency according to the judgment result to control the current resonance.

[0029] Preferably, by continuously collecting the load impedance X, the resonance condition trigger signal caused by the abnormal system impedance can be quickly captured. Comparing the real-time load impedance X with the load impedance set threshold X 阈 can quickly judge whether there is a situation where the impedance drops sharply and the current surges in parallel resonance and whether there is a situation where the impedance is extremely large, the system overheats or the energy coupling efficiency decreases in series resonance, so that the control method of the present invention can meet the working conditions with complex dynamic impedance characteristics in multi-source parallel and multi-load states, and prevent faults such as overcurrent, overheating, and inverter tube explosion caused by current resonance; moreover, 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 the set threshold value X of the load impedance 阈 , it is determined that there is no abnormality in the current resonance; if the real-time load impedance X is greater than the set threshold value X of the load impedance 阈 , it is determined that there is an abnormality in the current resonance.

[0031] Preferably, the control method of the present invention can accurately determine whether the current resonance state is abnormal by obtaining the real-time load impedance X and comparing it with the set threshold value X of the load impedance 阈 . When it is detected that the real-time load impedance X is greater than the set threshold value X of the load impedance 阈 , the system can immediately determine it as an abnormal resonance state, and accordingly adjust the output frequency of the inverter, thereby effectively avoiding the excitation of the resonance point, preventing faults such as overcurrent and overvoltage, and improving the operation safety and stability of the system; when the real-time load impedance X is less than the set threshold value X of the load impedance 阈 , the system determines that the resonance is normal and no frequency modulation intervention is required, which is beneficial to maintaining the high-efficiency working state of the system; moreover, the control method of the present invention has the advantages of strong real-time performance, fast response speed, simple control strategy, etc., can realize dynamic adaptive adjustment under variable load conditions, can significantly reduce the failure rate of the system under resonance conditions, improve the energy transmission efficiency and power quality, enhance the environmental adaptability of the system, and has high practical value.

[0032] Furthermore, in parallel resonance, in order to avoid the abnormal increase of the total impedance and cause the system to be unable to output current, the set threshold value X of the load impedance 阈 should be slightly less than the maximum impedance value when the system is in parallel resonance. At this time, when it is detected that the real-time load impedance X is greater than the set threshold value X of the load impedance 阈 , it is determined that there is an abnormality in the current resonance; in series resonance, in order to avoid the system entering the resonance point and prevent the current from being too large, the set threshold value X of the load impedance 阈 should be slightly greater than the minimum impedance value at the resonance point. At this time, when it is detected that the real-time load impedance X is greater than the set threshold value X of the load impedance 阈 , it is determined that there is an abnormality in the current resonance.

[0033] It should be noted that if it is detected that the real-time load impedance X is equal to the set threshold value X of the load impedance 阈 , it should be determined whether there is current resonance according to the actual situation, and no specific limitation is made here.

[0034] In some embodiments of the present invention, if there is an abnormality in the current resonance, according to the impedance-frequency characteristic curve library, the current resonance is controlled to migrate to the sub-optimal resonance point.

[0035] Preferably, the control method of the present invention can quickly locate a sub-optimal resonance point closer to the safe operating region by constructing an impedance-frequency characteristic curve library and combining the impedance data collected in real time. When it is detected that the current impedance exceeds the preset threshold, indicating resonance anomaly, the sub-optimal resonance point usually has a lower resonance current peak or a wider frequency tolerance band, which can effectively reduce the risks of overcurrent and overvoltage and avoid device damage. Moreover, compared with the traditional strategy of staying away from the resonance point, this method migrates towards the sub-optimal point, while avoiding overstress at the main resonance point, still keeps the system operating near the resonance region, thus maintaining a high power transfer efficiency or output power, and avoiding a significant decrease in system efficiency caused by excessive frequency drift. It is particularly suitable for application scenarios with high requirements for both efficiency and stability, such as LLC resonant converters, wireless charging for electric vehicles, photovoltaic grid-connected inverter systems, etc.

[0036] Furthermore, since the selection of the sub-optimal resonance point is based on the established impedance-frequency characteristic curve library, the system can achieve adaptive adjustment under factors such as different load conditions, temperature changes, and grid disturbances, and has good dynamic response capabilities. At the same time, the impedance-frequency characteristic curves adopted can be constructed based on simulation and measured data, with strong generality and high portability.

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

[0038] Preferably, when the system current resonance is in a normal state, the control method of the present invention continuously monitors the temperature T of the working environment or key devices, and dynamically adjusts the control strategy based on the temperature change to further optimize the system operation performance and ensure that the stability of the resonance state and the energy efficiency level do not shift due to temperature rise. Since temperature change will cause the actual values of key parameters such as inductance and capacitance in the resonance network to shift, resulting in resonance frequency drift, and further affecting the phase matching and energy transfer efficiency of the current resonance, therefore, through real-time temperature detection and combined with the preset temperature-parameter mapping relationship, the inverter control frequency, modulation method, or resonance parameters can be dynamically compensated to ensure that the system continuously operates at the optimal or sub-optimal resonance point and avoid performance degradation. Moreover, by further adopting temperature-assisted control, the energy efficiency performance and long-term stability of the resonance network can be significantly improved, avoiding resonance shift and efficiency decrease caused by high temperature, while reducing the thermal stress of power devices, prolonging the service life of devices, and enhancing the operation reliability of the entire system.

[0039] Furthermore, the control method of the present invention has predictive regulation ability, that is, when the resonance has not yet shown abnormalities, it can judge in advance the possible parameter changes caused by the temperature trend, and actively correct the control instructions to achieve feed-forward stable control. This temperature-driven dynamic adjustment effectively improves the adaptability of the system to environmental changes, and is particularly suitable for scenarios with large day-night temperature differences or significant periodic fluctuations in load, 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 according to 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 according to the comparison result; wherein, the first temperature threshold T1 is less than the second temperature threshold T2.

[0041] Preferably, by setting the first temperature threshold T1 and the second temperature threshold T2, the control method of the present invention dynamically monitors the real-time temperature T, adjusts the resonance control strategy of the system according to the comparison result of T and the thresholds, intervenes in compensation at the initial stage of temperature rise, delays the occurrence of high temperature, avoids frequent triggering of protection shutdown, improves the continuous operation time of the system, prevents key components from being damaged, broken down or aged due to overheating, and is particularly suitable for high-frequency, high-density power conversion systems; moreover, by timely correcting the resonance parameters through temperature feedback, it avoids the resonance frequency deviation caused by device thermal drift, and can improve the long-term stability and control accuracy of the current resonance system; while ensuring the stability of the resonance system, it improves the energy efficiency and safety of the system.

[0042] Preferably, since different temperature points represent different working states, the first temperature threshold T1 is less than the second temperature threshold T2, which can ensure that the system has the opportunity to relieve the temperature rise first and then perform protective treatment, rather than triggering protection as soon as the temperature rises, resulting in a significant drop in performance; 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, so control needs to be intervened in advance; the second temperature threshold T2 is usually set as the limit safety temperature. Exceeding the second temperature threshold T2 may cause problems such as thermal breakdown, capacitor insulation breakdown, and inductor magnetic core saturation failure, which belong to the state that requires 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 according to the comparison result, the stability of the system can be greatly improved, preventing misprotection or hardware failures caused by too late response.

[0043] In some embodiments of the present invention, controlling the current resonance according to the comparison result includes: if the real-time temperature T is less than the 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 less than the 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 will affect the parameters of components such as inductors and capacitors in the resonant circuit, thereby causing a shift in the resonant frequency. By setting two temperature thresholds, namely the first temperature threshold T1 and the second temperature threshold T2, the system can take corresponding control measures in different temperature ranges; when the real-time temperature T is less than the first temperature threshold T1, the system is in a normal operating state and no adjustment is required, maintaining the optimal resonant state to ensure efficient operation; when the real-time temperature T is greater than the first temperature threshold T1 and less than the second temperature threshold T2, the temperature is on an upward trend at this time. If no adjustment is made, it may cause a shift in the resonant frequency. In this case, by appropriately adjusting the inverter output frequency, the system can compensate for the resonant frequency shift caused by temperature, maintain near the optimal operating point, thereby reducing energy loss, improving energy transmission efficiency, avoiding a decrease in power factor caused by frequency shift, and at the same time extending the service life of the equipment; when the real-time temperature T is greater than the second temperature threshold T2, the temperature exceeds the safety threshold at this time. The system actively reduces the inverter output frequency, reduces the power output, prevents further temperature rise, and avoids performance degradation or damage caused by component overheating from affecting the normal operation of other associated devices.

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

[0046] It should be noted that if it is detected that the real-time temperature T is equal to the first temperature threshold T1 or the real-time temperature T is equal to the second temperature threshold T2, those skilled in the art should determine what adjustments need to be made according to the actual situation, and no specific limitations are made 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 a FIR filter and tracking the fundamental wave 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, during the processing of the phase signal φ, a dual filtering mechanism composed of a FIR filter and an adaptive Kalman filter is introduced, which can significantly improve the anti-interference ability and phase tracking accuracy of the system under complex current waveforms; the FIR filter is mainly used to suppress high-frequency harmonic interference in the input signal, and its linear phase characteristic can effectively prevent signal distortion and ensure that the phase information of the filtered signal does not shift, which is particularly crucial for a system with phase as the core parameter, especially in an environment with non-ideal factors such as high-frequency noise, electromagnetic interference, or rising-edge spikes; while the adaptive Kalman filter further performs fine estimation and dynamic tracking on the signal after FIR filtering. The advantage of this filter is that it can dynamically adjust its internal parameters according to the actual working state, especially the noise covariance matrix. By introducing the real-time current distortion rate as the adjustment basis, the system can adaptively sense changes in the external noise level and correspondingly optimize the gain of the filter, so that it can still stably and accurately extract the fundamental wave phase under different load, voltage, or temperature conditions.

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

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the present invention in each embodiment.

Claims

1. A control method for current resonance, characterized in that, Including: Collecting the real-time current phase signal φ; Adjusting the output frequency of the inverter according to the real-time current phase signal φ to control the current resonance.

2. The control method according to claim 1, wherein The adjusting the output frequency of the inverter according to the real-time current phase signal φ to control the current resonance includes: Obtaining the real-time load impedance X according to the real-time current phase signal φ; Controlling and adjusting the output frequency of the inverter according to the real-time load impedance X to control the current resonance.

3. The control method according to claim 2, wherein The adjusting the output frequency of the inverter according to the load impedance X to control the current resonance includes: Compare the real-time load impedance X with the set threshold value X of the load impedance 阈 for comparison Judging whether the current resonance is abnormal according to the comparison result; Adjusting the output frequency of the inverter according to the judgment result to control the current resonance.

4. The control method according to claim 3, wherein The judging whether the current resonance is abnormal according to the comparison result includes: If the real-time load impedance X is less than the load impedance setting threshold X 阈 , it is determined that there is no abnormality in the current resonance; If the real-time load impedance X is greater than the load impedance setting threshold X 阈 , it is determined that there is an abnormality in the current resonance.

5. The control method according to claim 4, wherein If the current resonance is abnormal, controlling the current resonance to migrate to the sub-optimal resonance point according to the impedance-frequency characteristic curve library.

6. The control method according to claim 4, wherein If the current resonance is not abnormal, Detecting the real-time temperature T; Controlling the current resonance according to the real-time temperature T.

7. The control method according to claim 6, wherein The controlling the current resonance according to the real-time temperature T includes: Comparing the real-time temperature T with the first temperature threshold T1 and the second temperature threshold T2; Controlling the current resonance according to the comparison result; Wherein, the first temperature threshold T1 is less than the second temperature threshold T2.

8. The control method according to claim 7, wherein The controlling the current resonance according to the comparison result includes: If the real-time temperature T is less than the first temperature threshold T1, controlling the current resonance not to change; If the real-time temperature T is greater than the first temperature threshold T1 and the real-time temperature T is less than the second temperature threshold T2, adjusting the output frequency of the inverter to correct the current resonance; If the real-time temperature T is greater than the second temperature threshold T2, adjusting the output frequency of the inverter to become smaller.

9. The control method according to claim 1, wherein, The phase signal φ is processed by a dual filtering mechanism, including: Eliminating high-frequency harmonic interference through a FIR filter and tracking the fundamental wave phase by 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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