An active filtering device and a vehicle-mounted device

Abstract

An embodiment of the present application discloses an active filtering device. The active filtering device includes: a noise sensing module, an impedance matching circuit, a controller, and a current injection circuit. By configuring the first equivalent impedance of the first impedance matching unit and the equivalent impedance of the second impedance matching unit in the embodiment of the present application, it is possible to make the current amplification coefficient control the current gain coefficient equal to or close to the natural number 1. When the current gain coefficient is equal to or close to the natural number 1, the equivalent impedance of the active filtering device will decrease, and the compensation current injected by the active filtering device into the three-phase line is likely to be all injected into the three-phase line without being shunted to other bypasses. Therefore, most or all of the compensation current output by the controller is injected into the three-phase line, so that the target noise current can be reliably and accurately canceled, improving the noise reduction effect.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of electronic technology, and involve an active filtering device and a vehicle-mounted device. Background Art

[0002] The active filtering device provided by the related technology detects the noise current in the load current in real time, and then generates a compensation current with the same magnitude and opposite direction as the noise current, and injects the compensation current into the power grid, so as to achieve dynamic compensation for harmonics and reactive power. The inventor found that not all of the injected compensation current is injected into the power grid, and part of the compensation current easily flows out from the bypass, and the actual compensation current injected into the power grid is less than the noise current, resulting in the compensation current injected into the power grid being unable to cancel out the noise current, and thus the noise reduction effect is low. Summary of the Invention

[0003] The main technical problem to be solved by the embodiments of the present application is to provide an active filtering device and a vehicle-mounted device to improve the technical problem of poor noise reduction effect in the related technology.

[0004] In a first aspect, an embodiment of the present application provides an active filtering device, including:

[0005] A noise sensing module, including three-phase coils, a collecting coil and a magnetic core, the three-phase coils and the collecting coil are respectively wound around the magnetic core, the three-phase coils are configured to transmit a three-phase AC power supply, and the collecting coil is configured to sense a current signal flowing through the three-phase coils;

[0006] An impedance matching circuit, including a first impedance matching unit and a second impedance matching unit, the first impedance matching unit and the second impedance matching unit are electrically connected at a preset series node, and the first impedance matching unit is electrically connected to the collecting coil;

[0007] A controller, electrically connected to the second impedance matching unit, configured to resolve a target noise current based on the current signal, and generate a compensation current with a phase opposite to that of the target noise current based on the target noise current;

[0008] A current injection circuit, electrically connected to the series node and also to the three-phase lines of the three-phase AC power supply, configured to inject the compensation current into the three-phase lines to cancel out the target noise current;

[0009] Wherein, the ratio of the second equivalent impedance of the second impedance matching unit to the first equivalent impedance of the first impedance matching unit plus the natural number 1 is the current amplification factor, the current gain factor of the compensation current is the product of a preset inherent factor and the current amplification factor, and the current amplification factor can make the current gain factor equal to the natural number 1.

[0010] Optionally, the first impedance matching unit includes a first resistor, a first capacitor, and a second capacitor. One end of the first resistor is electrically connected to the acquisition coil, the other end of the first resistor is electrically connected to one end of the first capacitor and one end of the second capacitor, and the other ends of the first capacitor and the second capacitor are both electrically connected to the series node. The first equivalent impedance is the equivalent impedance composed of the first resistor, the first capacitor, and the second capacitor.

[0011] Optionally, the second impedance matching unit includes a second resistor, a third capacitor, and a fourth capacitor. One end of the second resistor is electrically connected to the series node, the other end of the second resistor is electrically connected to one end of the third capacitor and one end of the fourth capacitor, and the other ends of the third capacitor and the fourth capacitor are both electrically connected to the controller. The second equivalent impedance is the equivalent impedance composed of the second resistor, the third capacitor, and the fourth capacitor.

[0012] Optionally, the current injection circuit includes a transformer and a three-way current injection unit;

[0013] The transformer includes a primary winding and a secondary winding. One end of the primary winding is electrically connected to the series node, the other end of the primary winding is grounded, one end of the secondary winding is electrically connected to the three-way current injection unit respectively, and the other end of the secondary winding is grounded;

[0014] Each current injection unit includes an injection capacitor unit and a Y-capacitor unit. One end of the injection capacitor unit is electrically connected to one end of the secondary winding, the other end of the injection capacitor unit is electrically connected to one end of the Y-capacitor unit and the corresponding phase coil in the three-phase coil respectively, and the other end of the Y-capacitor unit is grounded;

[0015] The inherent coefficient is jointly restricted by the first coupling coefficient of the transformer, the second coupling coefficient between the acquisition coil and the three-phase coil, the first turns ratio of the transformer, and the second turns ratio between the acquisition coil and the three-phase coil.

[0016] Optionally, the injection capacitor unit includes a plurality of injection capacitor sub-units connected in parallel, and each injection capacitor sub-unit includes a switch and an injection capacitor connected in series;

[0017] The Y-capacitor unit includes a Y-capacitor. One end of the Y-capacitor is electrically connected to the injection capacitor unit, and the other end of the Y-capacitor is grounded;

[0018] The controller is configured to: gate a target number of injection capacitor sub-units, determine a target noise frequency based on the target noise current, generate a compensation current based on the target noise frequency, such that the injection frequency applied to the target phase line by the compensation current under the action of the transformer, the gated injection capacitor sub-units, and the Y-capacitor corresponding to the target phase line is consistent with the target noise frequency, where the target phase line is the phase line corresponding to the gated injection capacitor sub-units.

[0019] Optionally, gating a target number of injection capacitor sub-units includes:

[0020] Obtain a noise ammeter, where the noise ammeter includes a plurality of noise currents detected during a historical noise reduction process;

[0021] Find the maximum noise frequency and the minimum noise frequency based on the noise ammeter;

[0022] Determine a target switch number based on the maximum noise frequency and the minimum noise frequency, where the target switch number is the number of switches that need to be closed;

[0023] Gate injection capacitor sub-units with a number consistent with the target switch number.

[0024] Optionally, the controller determines the target switch number based on the maximum noise frequency and the minimum noise frequency, including:

[0025] Determine a first candidate number based on the maximum noise frequency and the capacitance value of a single injection capacitor, where the first candidate number is the number of switches gated when the maximum injection frequency is greater than the maximum noise frequency, and the maximum noise frequency is inversely proportional to the first candidate number;

[0026] Determine a second candidate number based on the minimum noise frequency and the capacitance value of a single injection capacitor, where the second candidate number is the number of switches gated when the minimum injection frequency is less than the minimum noise frequency, and the minimum noise frequency is inversely proportional to the second candidate number;

[0027] Select the minimum candidate number between the first candidate number and the second candidate number as the target switch number.

[0028] Optionally, the current injection circuit further includes a voltage protection circuit, and the voltage protection circuit is electrically connected to both ends of the primary winding.

[0029] Optionally, the minimum induction frequency of the noise sensing module is jointly constrained by the input impedance of the controller, the first turns ratio, the second turns ratio, the self-inductance coefficient of the acquisition coil, the first coupling coefficient, and the second coupling coefficient.

[0030] In a second aspect, an embodiment of the present application provides a vehicle-mounted device, including the above-mentioned active filtering device.

[0031] By configuring the first equivalent impedance of the first impedance matching unit and the equivalent impedance of the second impedance matching unit, the embodiment of the present application can make the current amplification coefficient control current gain coefficient equal to or close to the natural number 1. When the current gain coefficient is equal to or close to the natural number 1, the equivalent impedance of the active filtering device will decrease, and the compensation current injected by the active filtering device into the three-phase line is likely to be all injected into the three-phase line without being shunted to other bypasses. Therefore, most or all of the compensation current output by the controller is injected into the three-phase line, so that the target noise current can be reliably and accurately canceled, improving the noise reduction effect. Description of the Drawings

[0032] One or more embodiments are exemplarily illustrated by corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the drawings in the figures do not constitute a proportional limitation.

[0033] Figure 1 It is a schematic structural diagram of an active filtering device provided by an embodiment of the present application;

[0034] Figure 2 It is a schematic structural diagram of an active filtering device provided by another embodiment of the present application;

[0035] Figure 3 Based on the Figure 2 shown circuit topology structure, it is a schematic structural diagram of a circuit model output by the present application;

[0036] Figure 4 It is a schematic structural diagram of a part of the specific circuit structure in an active filtering device provided by an embodiment of the present application;

[0037] Figure 5 It is a schematic structural diagram of an active filtering device provided by still another embodiment of the present application;

[0038] Figure 6 It is a schematic structural diagram of an active filtering device provided by still another embodiment of the present application;

[0039] Figure 7 It is a schematic structural diagram of another part of the specific circuit structure in an active filtering device provided by an embodiment of the present application;

[0040] Figure 8 It is a schematic structural diagram of an active filtering device provided by still another embodiment of the present application. Detailed Embodiments

[0041] For the convenience of understanding the present application, the present application will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is expressed as "fixed to" another element, it can be directly on the other element, or there can be one or more intermediate elements therebetween. When an element is expressed as "connected to" another element, it can be directly connected to the other element, or there can be one or more intermediate elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are only for the purpose of illustration.

[0042] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in this specification in the description of the present application are only for the purpose of describing specific embodiments and are not used to limit the present application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0043] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of an active filtering device provided by an embodiment of the present application. The active filtering device 10 is arranged between the power input terminal 101 and the power output terminal 102. The active filtering device 10 includes a noise sensing module 100 and a signal generating module 200. The noise sensing module 100 is electrically connected to the signal generating module 200.

[0044] The noise sensing module 100 includes a three-phase coil 11, a collecting coil 12 and a magnetic core 13. The three-phase coil 11 and the collecting coil 12 are respectively wound around the magnetic core 13.

[0045] The three-phase coil 11 is used to transmit a three-phase AC power supply. The three-phase coil 11 includes a first-phase coil A, a second-phase coil B and a third-phase coil C. The first-phase coil A is used to transmit the AC power supply from the A-phase line, the second-phase coil B is used to transmit the AC power supply from the B-phase line, and the third-phase coil C is used to transmit the AC power supply from the C-phase line.

[0046] The collecting coil 12 and the three-phase coil 11 are wound side by side around the magnetic core 13. The current flowing through the three-phase coil 11 is likely to cause a change in the magnetic field. The changing magnetic field can generate a current on the collecting coil 12, that is, the collecting coil 12 can sense the current signal flowing through the three-phase coil. The collecting coil 12 collects the current signal associated with the three-phase AC power supply based on the electrical isolation method, shielding the influence of strong electricity on the downstream weak electricity circuit.

[0047] The signal generating module 200 is electrically connected to the noise sensing module 100. As Figure 1As shown, the signal generation module 200 analyzes the target noise current based on the current signal, generates a compensation current with a phase opposite to that of the target noise current based on the target noise current, and injects the compensation current into the three-phase line.

[0048] The specific working process is as follows: First, the AC power supply enters the active filter device through the power input terminal 101, and there are various electromagnetic interference noises on the three-phase line. The noise sensing module 100 collects the current signal associated with the three-phase AC power supply based on the electrical isolation method. The current signal is transmitted to the signal generation module 200 for processing. The signal generation module 200 analyzes the target noise current based on the current signal, generates a compensation current with a phase opposite to that of the target noise current based on the target noise current, and injects the compensation current into the three-phase line. After the compensation current is injected into the three-phase line, it cancels out the target noise current. The AC power supply after active filtering is output from the power output terminal 102, and the electromagnetic interference is effectively suppressed.

[0049] Through the above active filtering process, the active filter device can significantly reduce the number of common-mode chokes or the necessary inductance of the common-mode chokes, enabling the active filter device to fully exert its noise reduction performance, thereby greatly reducing the size of the filter board of the active filter device. This technology is applicable to the in-vehicle environment with limited space, can provide a cleaner power environment for in-vehicle electronic devices, and reduce the impact of electromagnetic interference on the normal operation of the devices.

[0050] Please refer to Figure 2 , the signal generation module 200 includes an impedance matching circuit 21, a controller 22, and a current injection circuit 23.

[0051] The impedance matching circuit 21 includes a first impedance matching unit 211 and a second impedance matching unit 212. The first impedance matching unit 211 and the second impedance matching unit 212 are electrically connected at a preset series node N1, and the first impedance matching unit 21 is electrically connected to the acquisition coil 12.

[0052] The controller 22 is electrically connected to the second impedance matching unit 212 and is used to analyze the target noise current based on the current signal and generate a compensation current with a phase opposite to that of the target noise current. For example, the controller 22 analyzes the target noise current from the current signal based on algorithms such as the Fourier transform algorithm or the wavelet transform algorithm, and then generates a compensation current with a phase opposite to that of the target noise current based on the inverse phase processing algorithm.

[0053] The current injection circuit 23 is electrically connected at the series node N1 and is also connected to the three-phase lines of the three-phase AC power supply, and is used to inject the compensation current into the three-phase lines to cancel the target noise current.

[0054] The sum of the ratio of the second equivalent impedance of the second impedance matching unit 212 to the first equivalent impedance of the first impedance matching unit 211 and the natural number 1 is the current amplification factor. The current gain factor of the compensation current is the product of a preset inherent factor and the current amplification factor, and the current amplification factor can make the current gain factor equal to the natural number 1.

[0055] Based on Figure 2 the circuit topology shown, the embodiment of the present application gives a circuit model as Figure 3 shown. In Figure 3 the circuit model shown, Z L is the equivalent impedance observed from the first line impedance stabilization network (LISN) to the active filtering device, and Z n is the equivalent impedance observed from the active filtering device to the second line impedance stabilization network. i x and i L respectively represent the currents flowing through Z n and Z L , and i inj represents the compensation current injected by the active filtering device into the three-phase line.

[0056] Based on Figure 3 the circuit model shown, there is: , is the current gain factor, and the current gain factor is the ratio between the compensation current output by the active filtering device within the operating frequency range and the detected target noise current.

[0057] Based on Figure 2 the circuit structure shown, the current gain factor is: , is the inherent factor, is the current amplification factor, and the inherent factor is related to the parameters of some circuit components of the current injection circuit 33.

[0058] The embodiment of the present application calculates the current amplification factor according to the following formula, as follows: , is the current amplification factor, is the first equivalent impedance, is the second equivalent impedance, is the input impedance of the controller. The input impedance is usually a value between 1 ohm and 5 ohms, and the input impedance is small and can be ignored.

[0059] Based on Figure 3 the circuit model shown, there is: , is the equivalent impedance of the active filtering device. It can be seen from this formula that when the current gain coefficient is close to 1, the equivalent impedance of the active filtering device will be greatly reduced, or will be close to or equal to 0.

[0060] By configuring the first equivalent impedance of the first impedance matching unit 211 and the equivalent impedance of the second impedance matching unit 212 in the embodiment of the present application, the current amplification coefficient can control the current gain coefficient to be equal to or close to the natural number 1. When the current gain coefficient is equal to or close to the natural number 1, the equivalent impedance of the active filtering device will decrease. It is easy for the compensation current injected by the active filtering device into the three-phase line to be all injected into the three-phase line without being shunted to other bypasses, such as Figure 3 the circuit model shown. At this time, the current i L will decrease, and the real compensation current i inj injected into the three-phase line will increase. In this way, the target noise current can be reliably and accurately canceled, improving the noise reduction effect.

[0061] Please refer to Figure 4 . The first impedance matching unit 211 includes a first resistor R1, a first capacitor C1 and a second capacitor C2. One end of the first resistor R1 is electrically connected to the acquisition coil 12, and the other end of the first resistor R1 is electrically connected to one end of the first capacitor C1 and one end of the second capacitor C2. The other ends of the first capacitor C1 and the second capacitor C2 are both electrically connected to the series node N1. The first equivalent impedance is the equivalent impedance composed of the first resistor R1, the first capacitor C1 and the second capacitor C2.

[0062] Please continue to refer to Figure 4 . The second impedance matching unit 212 includes a second resistor R2, a third capacitor C3 and a fourth capacitor C4. One end of the second resistor R2 is electrically connected to the series node N1, and the other end of the second resistor R2 is electrically connected to one end of the third capacitor C3 and one end of the fourth capacitor C4. The other ends of the third capacitor C3 and the fourth capacitor C4 are both electrically connected to the controller 22. The second equivalent impedance is the equivalent impedance composed of the second resistor R2, the third capacitor C3 and the fourth capacitor C4.

[0063] Please refer to Figure 5 . The current injection circuit 23 includes a transformer 231 and three current injection units, where the three current injection units are respectively the first current injection unit 232, the second current injection unit 233 and the third current injection unit 234.

[0064] As shown in Figure 4As shown, the transformer 231 includes a primary winding 2311 and a secondary winding 2312. One end of the primary winding 2311 is electrically connected to the series node N1, and the other end of the primary winding 2311 is grounded. One end of the secondary winding 2312 is respectively electrically connected to three current injection units, and the other end of the secondary winding 2312 is grounded.

[0065] As Figure 5 shown, each current injection unit includes an injection capacitor unit 2301 and a Y capacitor unit 2302. One end of the injection capacitor unit 2301 is electrically connected to one end of the secondary winding 2312. The other end of the injection capacitor unit 2301 is respectively electrically connected to one end of the Y capacitor unit 2302 and the corresponding phase coil in the three-phase coil. The other end of the Y capacitor unit 2302 is grounded.

[0066] For example, one end of the injection capacitor unit 2301 of the first current injection unit 232 is electrically connected to one end of the secondary winding 2312. The other end of the injection capacitor unit 2301 is respectively electrically connected to one end of the Y capacitor unit 2302 and the first-phase coil A. The other end of the Y capacitor unit 2302 is grounded.

[0067] One end of the injection capacitor unit 2301 of the second current injection unit 233 is electrically connected to one end of the secondary winding 2312. The other end of the injection capacitor unit 2301 is respectively electrically connected to one end of the Y capacitor unit 2302 and the second-phase coil B. The other end of the Y capacitor unit 2302 is grounded.

[0068] One end of the injection capacitor unit 2301 of the third current injection unit 234 is electrically connected to one end of the secondary winding 2312. The other end of the injection capacitor unit 2301 is respectively electrically connected to one end of the Y capacitor unit 2302 and the third-phase coil C. The other end of the Y capacitor unit 2302 is grounded.

[0069] Intrinsic coefficient is jointly constrained by the first coupling coefficient of the transformer 231, the second coupling coefficient between the acquisition coil and the three-phase coil, the first turns ratio of the transformer, and the second turns ratio between the acquisition coil and the three-phase coil. For example, according to the following formula, the intrinsic coefficient can be obtained:

[0070]

[0071] is the first coupling coefficient, is the second coupling coefficient, is the first turns ratio, is the second turns ratio.

[0072] The minimum induction frequency of the noise sensing module is jointly constrained by the input impedance of the controller, the first turn ratio, the second turn ratio, the self-inductance coefficient of the acquisition coil, the first coupling coefficient, and the second coupling coefficient. For example, according to the following formula, the minimum induction frequency can be obtained:

[0073]

[0074] is the minimum induction frequency, is the input impedance, is the first turn ratio, is the second turn ratio, is the self-inductance coefficient, is the first coupling coefficient, is the second coupling coefficient.

[0075] Please refer to Figure 6 , the current injection circuit 23 further includes a voltage protection circuit 235, and the voltage protection circuit 235 is electrically connected to both ends of the primary winding 2311. When an abnormally high voltage appears in the active filtering device, the voltage protection circuit 235 can prevent the transformer 231 from having an excessive voltage and damaging the transformer 231.

[0076] Please combine with Figure 4 , the voltage protection circuit 235 includes a transient voltage suppression diode TVS, and the transient voltage suppression diode TVS is electrically connected to both ends of the primary winding 2311. When a momentary high voltage appears in the active filtering device and the high voltage exceeds the breakdown voltage of the transient voltage suppression diode TVS, the transient voltage suppression diode TVS will quickly conduct, forming a low-impedance path to guide the momentary large current to the ground, thereby limiting the voltage at both ends of the transformer 231 and protecting the transformer 231 from the impact of excessive voltage. When the transient voltage disappears, the transient voltage suppression diode TVS will return to the high-impedance state again, without affecting the normal operation of the active filtering device.

[0077] In order to elaborate in detail the working principle of the active filtering device provided by the embodiments of the present application, the embodiments of the present application combine Figure 4 with Figure 7 to make a detailed description as follows:

[0078] The noise sensing module 100 is arranged on the main circuit where the three-phase AC power supply supplies power to the load. Among them, the AC power supply passes through one of the first-phase coil A, the second-phase coil B, and the third-phase coil C. The acquisition coil 12 can sense the current passing through one of the first-phase coil A, the second-phase coil B, and the third-phase coil C and obtain a current signal.

[0079] The current signal induced by the acquisition coil 12 is sequentially transmitted to the first impedance matching unit 211 and the second impedance matching unit 212 through the terminal S+ and the terminal S-, and finally transmitted to the controller 22.

[0080] The controller 22 analyzes the target noise current based on the current signal, generates a compensation current with a phase opposite to that of the target noise current based on the target noise current, and sequentially passes the compensation current through the transformer 231, the injection capacitor unit corresponding to the phase, and the phase coil corresponding to the phase, completing the process of injecting the compensation current into the three-phase line.

[0081] In the embodiment of the present application, by configuring the first equivalent impedance of the first impedance matching unit 211 and the equivalent impedance of the second impedance matching unit 212, the current amplification factor Control current gain factor is equal to or close to the natural number 1. When the current gain factor is equal to or close to the natural number 1, the equivalent impedance of the active filtering device will decrease. The compensation current injected by the active filtering device into the three-phase line is likely to be all injected into the three-phase line without being shunted to other bypasses. Therefore, most or all of the compensation current output by the controller 22 is injected into the three-phase line, so that the target noise current can be reliably and accurately cancelled, improving the noise reduction effect.

[0082] In some embodiments, please refer to Figure 8 , the injection capacitor unit 2301 includes a plurality of injection capacitor sub-units 81 connected in parallel, and each injection capacitor sub-unit 81 includes a switch SW and an injection capacitor SC connected in series. The Y capacitor unit 2302 includes a Y capacitor. One end of the Y capacitor is electrically connected to the injection capacitor unit 2301, and the other end of the Y capacitor is grounded.

[0083] The inventors found that the bandwidth of the active filtering device provided by the related technology is fixed. When the noise frequency exceeds the bandwidth of the active filtering device and the frequency of the compensation current output by the active filtering device does not fall within the bandwidth of the active filtering device, the compensation current is likely to be attenuated, resulting in the compensation current being unable to effectively cancel the noise current and the noise suppression effect being poor.

[0084] In the embodiment of the present application, the controller 22 is used to select a target number of injection capacitor sub-units, determine the target noise frequency based on the target noise current, and generate a compensation current based on the target noise frequency, so that the injection frequency applied to the target phase line is the same as the target noise frequency under the action of the transformer, the selected injection capacitor sub-units, and the Y capacitor corresponding to the target phase line.

[0085] The target phase line is the phase line corresponding to the selected injection capacitor sub-unit. For example, if the selected injection capacitor sub-unit corresponds to the A-phase line, the target phase line is the A-phase line. Similarly, if the selected injection capacitor sub-unit corresponds to the B-phase line, the target phase line is the B-phase line. If the selected injection capacitor sub-unit corresponds to the C-phase line, the target phase line is the C-phase line.

[0086] Based on Figure 4 and Figure 7 the circuit structure shown, the expression for the minimum injection frequency provided by the embodiments of the present application is:

[0087]

[0088] is the minimum injection frequency, is the first turns ratio, is the self-inductance coefficient of the transformer, is the total capacitance value of the selected injection capacitor sub-units, is the Y-capacitor corresponding to the target phase line.

[0089] The expression for the maximum injection frequency provided by the embodiments of the present application is:

[0090]

[0091] is the minimum injection frequency, is the first coupling coefficient.

[0092] From the above two expressions, it can be seen that both the minimum injection frequency and the maximum injection frequency are related to the total capacitance value of the selected injection capacitor sub-units.

[0093] If the acquisition coil 12 acquires the current signal of the A-phase line, the controller 22 selects a target number of injection capacitor sub-units in the injection capacitor unit 2301 of the first current injection unit 232, so that the bandwidth of the active filtering device can be extended to at least include various noise frequencies, enabling the compensation current output by the controller to be compatible with various noise reduction situations and suppressing various noise currents.

[0094] The controller 22 analyzes the target noise current from the A-phase line in the current signal, and then the controller 22 determines the target noise frequency based on the target noise current and generates a compensation current based on the target noise frequency, so that the injection frequency applied to the A-phase line by the compensation current under the action of the transformer, the selected injection capacitor sub-units, and the Y-capacitor corresponding to the A-phase line is consistent with the target noise frequency.

[0095] If the acquisition coil 12 acquires the current signal of the B-phase line, the controller 22 selects a target number of injection capacitor sub-units in the injection capacitor unit 2301 of the first current injection unit 232. The controller 22 resolves the target noise current from the B-phase line from the current signal, determines the target noise frequency based on the target noise current, and generates a compensation current based on the target noise frequency, so that the injection frequency applied to the B-phase line is consistent with the target noise frequency under the action of the transformer, the selected injection capacitor sub-units, and the Y-capacitor corresponding to the B-phase line.

[0096] If the acquisition coil 12 acquires the current signal of the C-phase line, the controller 22 selects a target number of injection capacitor sub-units in the injection capacitor unit 2301 of the first current injection unit 232. The controller 22 resolves the target noise current from the C-phase line from the current signal, determines the target noise frequency based on the target noise current, and generates a compensation current based on the target noise frequency, so that the injection frequency applied to the C-phase line is consistent with the target noise frequency under the action of the transformer, the selected injection capacitor sub-units, and the Y-capacitor corresponding to the C-phase line.

[0097] In some embodiments, the controller 22 selecting a target number of injection capacitor sub-units includes: obtaining a noise ammeter, the noise ammeter including a plurality of noise currents detected during the historical noise reduction process, finding the maximum noise frequency and the minimum noise frequency based on the noise ammeter, determining the target switch number based on the maximum noise frequency and the minimum noise frequency, the target switch number being the number of switches that need to be closed, and selecting the injection capacitor sub-units with the number of selections being consistent with the target switch number.

[0098] The historical noise reduction process refers to the process in the past time when the active filtering device generates a compensation current to cancel the noise current. The controller 22 records the noise frequency of each noise current in the noise ammeter during each noise reduction process. The controller 22 compares any two noise frequencies in the noise ammeter and finds the maximum noise frequency and the minimum noise frequency therefrom.

[0099] The controller determining the target switch number based on the maximum noise frequency and the minimum noise frequency includes: determining a first candidate number based on the maximum noise frequency and the capacitance value of a single injection capacitor, the first candidate number being the number of switches selected when the maximum injection frequency is greater than the maximum noise frequency, and the maximum noise frequency being inversely proportional to the first candidate number; determining a second candidate number based on the minimum noise frequency and the capacitance value of a single injection capacitor, the second candidate number being the number of switches selected when the minimum injection frequency is less than the minimum noise frequency, and the minimum noise frequency being inversely proportional to the second candidate number; and selecting the minimum candidate number between the first candidate number and the second candidate number as the target switch number.

[0100] For example, in the embodiments of the present application, the minimum noise frequency is found from the noise ammeter as , the maximum noise frequency is , and there is the following expression:

[0101]

[0102]

[0103]

[0104]

[0105] is the total capacitance value corresponding to the minimum noise frequency and for which the injection capacitor sub-units need to be gated, is the total capacitance value corresponding to the maximum noise frequency and for which the injection capacitor sub-units need to be gated, is the capacitance value of a single injection capacitor, is the first candidate quantity, is the second candidate quantity.

[0106] In the embodiments of the present application, the minimum candidate quantity is selected as the target switch quantity between the first candidate quantity and the second candidate quantity . For example, if the first candidate quantity is 2 and the second candidate quantity is 1, then the target switch quantity is 1. In this way, the embodiments of the present application can adaptively adjust the bandwidth to adapt to the noise frequencies of various noise currents, thereby ensuring that various noise currents can be reliably and accurately suppressed.

[0107] Based on the active filtering device provided in each of the above embodiments, the embodiments of the present application further provide a vehicle-mounted device, and this vehicle-mounted device includes the active filtering device provided in the foregoing embodiments.

[0108] It should be noted that the description and drawings of the present application give preferred embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in this specification. These embodiments are not additional limitations to the content of the present application. The purpose of providing these embodiments is to make the understanding of the disclosed content of the present application more thorough and comprehensive. Further, the above technical features continue to be combined with each other to form various embodiments not listed above, all of which are regarded as the scope described in the specification of the present application; furthermore, for those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present application.

Claims

1. An active filtering device, characterized in that, Comprising: A noise sensing module, including a three-phase coil, a collecting coil and a magnetic core. The three-phase coil and the collecting coil are respectively wound around the magnetic core. The three-phase coil is configured to transmit a three-phase AC power supply, and the collecting coil is configured to sense the current signal flowing through the three-phase coil; An impedance matching circuit, including a first impedance matching unit and a second impedance matching unit. The first impedance matching unit and the second impedance matching unit are electrically connected at a preset series node, and the first impedance matching unit is electrically connected to the collecting coil; A controller, electrically connected to the second impedance matching unit, configured to resolve a target noise current based on the current signal, and generate a compensation current with a phase opposite to that of the target noise current based on the target noise current; A current injection circuit, electrically connected to the series node and also electrically connected to the three-phase lines of the three-phase AC power supply, configured to inject the compensation current into the three-phase lines to cancel the target noise current; Wherein, the sum of the ratio of the second equivalent impedance of the second impedance matching unit to the first equivalent impedance of the first impedance matching unit and the natural number 1 is the current amplification factor, and the current gain factor of the compensation current is the product of a preset inherent factor and the current amplification factor, and the current amplification factor can make the current gain factor equal to the natural number 1.

2. The active filtering device according to claim 1, wherein The first impedance matching unit includes a first resistor, a first capacitor and a second capacitor. One end of the first resistor is electrically connected to the collecting coil, the other end of the first resistor is electrically connected to one end of the first capacitor and one end of the second capacitor, and the other ends of the first capacitor and the second capacitor are both electrically connected to the series node. The first equivalent impedance is the equivalent impedance composed of the first resistor, the first capacitor and the second capacitor.

3. The active filtering device according to claim 1, characterized in that The second impedance matching unit includes a second resistor, a third capacitor and a fourth capacitor. One end of the second resistor is electrically connected to the series node, the other end of the second resistor is electrically connected to one end of the third capacitor and one end of the fourth capacitor, and the other ends of the third capacitor and the fourth capacitor are both electrically connected to the controller. The second equivalent impedance is the equivalent impedance composed of the second resistor, the third capacitor and the fourth capacitor.

4. The active filtering device according to any one of claims 1 to 3, wherein The current injection circuit includes a transformer and 3 current injection units; The transformer includes a primary winding and a secondary winding. One end of the primary winding is electrically connected to the series node, the other end of the primary winding is grounded, one end of the secondary winding is respectively electrically connected to the 3 current injection units, and the other end of the secondary winding is grounded; Each current injection unit includes an injection capacitor unit and a Y-capacitor unit. One end of the injection capacitor unit is electrically connected to one end of the secondary winding, the other end of the injection capacitor unit is respectively electrically connected to one end of the Y-capacitor unit and the corresponding phase coil in the three-phase coil, and the other end of the Y-capacitor unit is grounded; The inherent coefficient is jointly constrained by the first coupling coefficient of the transformer, the second coupling coefficient between the acquisition coil and the three-phase coil, the first turns ratio of the transformer, and the second turns ratio between the acquisition coil and the three-phase coil.

5. The active filtering device according to claim 4, wherein the injection capacitor unit includes a plurality of injection capacitor sub-units connected in parallel, and each injection capacitor sub-unit includes a switch and an injection capacitor connected in series; the Y-capacitor unit includes a Y-capacitor, one end of the Y-capacitor is electrically connected to the injection capacitor unit, and the other end of the Y-capacitor is grounded; the controller is configured to: select a target number of injection capacitor sub-units; determine a target noise frequency based on the target noise current; generate a compensation current based on the target noise frequency, so that the injection frequency applied to the target phase line by the compensation current under the action of the transformer, the selected injection capacitor sub-units, and the Y-capacitor corresponding to the target phase line is consistent with the target noise frequency, and the target phase line is the phase line corresponding to the selected injection capacitor sub-units.

6. The active filtering device according to claim 5, characterized in that, The selection of a target number of injection capacitor sub-units includes: obtain a noise ammeter, and the noise ammeter includes a plurality of noise currents detected during the historical noise reduction process; find the maximum noise frequency and the minimum noise frequency based on the noise ammeter; determine a target switch number based on the maximum noise frequency and the minimum noise frequency, and the target switch number is the number of switches that need to be closed; select injection capacitor sub-units with a number consistent with the target switch number.

7. The active filtering device according to claim 6, characterized in that, The controller determines the target switch number based on the maximum noise frequency and the minimum noise frequency, including: determine a first candidate number based on the maximum noise frequency and the capacitance value of a single injection capacitor, and the first candidate number is the number of switches selected when the maximum injection frequency is greater than the maximum noise frequency, and the maximum noise frequency is inversely proportional to the first candidate number; determine a second candidate number based on the minimum noise frequency and the capacitance value of a single injection capacitor, and the second candidate number is the number of switches selected when the minimum injection frequency is less than the minimum noise frequency, and the minimum noise frequency is inversely proportional to the second candidate number; select the minimum candidate number between the first candidate number and the second candidate number as the target switch number.

8. The active filtering device according to claim 4, characterized in that, The current injection circuit further includes a voltage protection circuit, and the voltage protection circuit is electrically connected to both ends of the primary winding.

9. The active filtering device according to claim 4, wherein The minimum induction frequency of the noise sensing module is jointly constrained by the input impedance of the controller, the first turns ratio, the second turns ratio, the self-inductance coefficient of the acquisition coil, the first coupling coefficient, and the second coupling coefficient.

10. A vehicle-mounted device, characterized in that, including: the active filtering device according to any one of claims 1-9.

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