Active filtering device and vehicle-mounted equipment

Abstract

The embodiment of the invention discloses an active filtering device. The active filtering device comprises 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, the current gain coefficient can be controlled to be equal to or close to the natural number 1 by the current amplification coefficient, and when the current gain coefficient is equal to or close to the natural number 1, the equivalent impedance of the active filtering device can be reduced; the compensation current injected into the three-phase line by the active filtering device is easily and completely injected into the three-phase line and cannot be shunted to other bypasses, so that most or all of the compensation current output by the controller is injected into the three-phase line, the target noise current can be reliably and accurately offset, and the noise reduction effect is improved.

Description

Technical Field

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

[0002] The active filter device provided by the related art detects the noise current in the load current in real time, then generates a compensation current of equal magnitude and opposite direction to the noise current, and injects the compensation current into the power grid, thereby achieving dynamic compensation for harmonics and reactive power. The inventors found that the compensation current injected by the related art is not all injected into the power grid, and part of the compensation current is easy to flow out from the bypass. The compensation current actually injected into the power grid is less than the noise current, resulting in the compensation current injected into the power grid being unable to offset the noise current, which in turn leads to a low noise reduction effect. Summary of the invention

[0003] The main technical problem 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 related technologies.

[0004] In a first aspect, an embodiment of the present application provides an active filtering device, comprising: A noise sensing module, comprising a three-phase coil, a collection coil and a magnetic core, wherein the three-phase coil and the collection coil are respectively wound on the magnetic core, the three-phase coil is configured to transmit a three-phase alternating current power supply, and the collection coil is configured to sense a current signal flowing through the three-phase coil; An impedance matching circuit, comprising a first impedance matching unit and a second impedance matching unit, wherein the first impedance matching unit and the second impedance matching unit are electrically connected to a preset series node, and the first impedance matching unit is electrically connected to the acquisition 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 having 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 to the three-phase line of the three-phase AC power source, configured to inject the compensation current into the three-phase line to offset the target noise current; Among them, 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 coefficient of the compensation current is the product of a preset inherent coefficient and the current amplification factor, and the current amplification factor can make the current gain coefficient equal to the natural number 1.

[0005] 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, the other end of the first capacitor and the other end of the second capacitor are both electrically connected to the series node, and the first equivalent impedance is an equivalent impedance composed of the first resistor, the first capacitor and the second capacitor.

[0006] 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, the other end of the third capacitor and the other end of the fourth capacitor are both electrically connected to the controller, and the second equivalent impedance is an equivalent impedance composed of the second resistor, the third capacitor and the fourth capacitor.

[0007] Optionally, the current injection circuit includes a transformer and three current injection units; The transformer comprises 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 current injection units respectively, and the other end of the secondary winding is grounded; Each current injection unit comprises 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 of the three-phase coil, and the other end of the Y capacitor unit is grounded; The natural coefficient is constrained by a first coupling coefficient of the transformer, a second coupling coefficient between the acquisition coil and the three-phase coil, a first turns ratio of the transformer, and a second turns ratio between the acquisition coil and the three-phase coil.

[0008] Optionally, the injection capacitor unit includes a plurality of injection capacitor sub-units connected in parallel, and each of the injection capacitor sub-units 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: enable a target number of injection capacitor subunits, determine a 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 of the compensation current applied to the target phase line under the action of the transformer, the enabled injection capacitor subunits 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 enabled injection capacitor subunit.

[0009] Optionally, the gated target number of injection capacitor subunits includes: Obtaining a noise current table, the noise current table including a plurality of noise currents detected during a historical noise reduction process; Find out the maximum noise frequency and the minimum noise frequency based on the noise current table; Determine a target number of switches based on the maximum noise frequency and the minimum noise frequency, the target number of switches being the number of switches that need to be closed; The number of injection capacitor subunits that is consistent with the target switch number is selected.

[0010] Optionally, the controller determines a target switch quantity based on the maximum noise frequency and the minimum noise frequency, comprising: Determine 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 that are turned on 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, the second candidate number being the number of switches that are turned on 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; A minimum candidate number is selected between the first candidate number and the second candidate number as the target switch number.

[0011] Optionally, the current injection circuit further includes a voltage protection circuit, and the voltage protection circuit is electrically connected to two ends of the primary winding.

[0012] Optionally, the minimum induction frequency of the noise sensing module is constrained by the input impedance of the controller, the first turns ratio, the second turns ratio, the self-inductance of the acquisition coil, the first coupling coefficient, and the second coupling coefficient.

[0013] In a second aspect, an embodiment of the present application provides a vehicle-mounted device, comprising the above-mentioned active filtering device.

[0014] The embodiment of the present application configures the first equivalent impedance of the first impedance matching unit and the equivalent impedance of the second impedance matching unit, so that the current amplification factor controls the current gain factor to be 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 filter device will decrease, and the compensation current injected into the three-phase line by the active filter device will be easily injected into the three-phase line instead of being diverted 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 offset, thereby improving the noise reduction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by corresponding drawings, which do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and the figures in the drawings do not constitute proportional limitations unless otherwise stated.

[0016] Figure 1 A schematic diagram of the structure of an active filtering device provided in an embodiment of the present application; Figure 2 A schematic structural diagram of an active filtering device provided in another embodiment of the present application; Figure 3 Based on the embodiments of the present application Figure 2 A schematic diagram of a circuit model outputted by the circuit topology structure shown; Figure 4 A schematic diagram of a specific circuit structure of a part of an active filtering device provided in an embodiment of the present application; Figure 5 A schematic structural diagram of an active filtering device provided in yet another embodiment of the present application; Figure 6 A schematic structural diagram of an active filtering device provided in yet another embodiment of the present application; Figure 7 A schematic diagram of another specific circuit structure of an active filter device provided in an embodiment of the present application; Figure 8 A schematic structural diagram of an active filtering device provided in yet another embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are for illustrative purposes only.

[0018] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0019] See also Figure 1 , Figure 1 The active filter device 10 is provided between a power input terminal 101 and a power output terminal 102, and 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.

[0020] The noise sensing module 100 includes a three-phase coil 11, a collection coil 12 and a magnetic core 13. The three-phase coil 11 and the collection coil 12 are respectively wound on the magnetic core 13.

[0021] The three-phase coil 11 is used to transmit three-phase AC power. 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 AC power from the A-phase line, the second-phase coil B is used to transmit AC power from the B-phase line, and the third-phase coil C is used to transmit AC power from the C-phase line.

[0022] The acquisition coil 12 and the three-phase coil 11 are arranged side by side on the magnetic core 13. The current flowing through the three-phase coil 11 easily causes the change of the magnetic field. The changing magnetic field can generate current on the acquisition coil 12, that is, the acquisition coil 12 can sense the current signal flowing through the three-phase coil. The acquisition 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 current on the downstream weak current circuit.

[0023] The signal generating module 200 is electrically connected to the noise sensing module 100. Figure 1As shown, the signal generating module 200 parses the target noise current based on the current signal, generates a compensation current with a phase opposite to the target noise current based on the target noise current, and injects the compensation current into the three-phase line.

[0024] The specific working process is as follows: First, the AC power supply enters the active filtering 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 parses the target noise current based on the current signal, generates a compensation current with a phase opposite to 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 electromagnetic interference is effectively suppressed.

[0025] Through the above-mentioned active filtering process, the active filtering device can significantly reduce the number of common-mode chokes or the necessary common-mode choke inductance, so that the active filtering device can fully exert its noise reduction performance, thereby greatly reducing the size of the filter board of the active filtering device. This technology is suitable for space-constrained vehicle environments, and can provide a purer power supply environment for vehicle-mounted electronic equipment, reducing the impact of electromagnetic interference on the normal operation of the equipment.

[0026] See also Figure 2 The signal generating module 200 includes an impedance matching circuit 21 , a controller 22 and a current injection circuit 23 .

[0027] 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 to a preset series node N1 , and the first impedance matching unit 21 is electrically connected to the collection coil 12 .

[0028] The controller 22 is electrically connected to the second impedance matching unit 212, and is used to parse out the target noise current based on the current signal, and generate a compensation current with a phase opposite to the target noise current based on the target noise current. For example, the controller 22 parses out the target noise current from the current signal based on an algorithm such as a Fourier transform algorithm or a wavelet transform algorithm, and then generates a compensation current with a phase opposite to the target noise current based on an inversion processing algorithm.

[0029] The current injection circuit 23 is electrically connected to the series node N1 and also to the three-phase line of the three-phase AC power source, and is used for injecting a compensation current into the three-phase line to offset the target noise current.

[0030] 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, and the current gain coefficient of the compensation current is the product of the preset inherent coefficient and the current amplification factor. The current amplification factor can make the current gain coefficient equal to the natural number 1.

[0031] based on Figure 2 The circuit topology shown in the embodiment of the present application is as follows Figure 3 The circuit model is shown in Figure 3 In the circuit model shown, Z L To observe the equivalent impedance from the first line impedance stabilization network (LISN) to the active filter device, Z n The equivalent impedance from the active filter device to the second line impedance stabilization network is observed. x and i L Respectively represent the flow through Z n and Z L The current, i inj It represents the compensation current injected into the three-phase line by the active filter device.

[0032] based on Figure 3 The circuit model shown has: , is the current gain coefficient, the current gain coefficient It is the ratio between the compensation current output by the active filter device within the operating frequency range and the detected target noise current.

[0033] based on Figure 2 The circuit structure shown, the current gain coefficient for: , is the intrinsic coefficient, is the current amplification factor, the inherent coefficient It is related to the parameters of some circuit components of the current injection circuit 33 .

[0034] The current amplification factor is calculated according to the following formula in the present application: , is the current amplification factor, is the first equivalent impedance, is the second equivalent impedance, is the input impedance of the controller. Input impedance Usually a value between 1 ohm and 5 ohms, input impedance Small and can be ignored.

[0035] based on Figure 3 The circuit model shown has: , is the equivalent impedance of the active filter device. From this formula, we can know that when the current gain coefficient When it is close to 1, the equivalent impedance of the active filter device will decrease significantly, or will be close to or equal to 0.

[0036] The embodiment of the present application configures the first equivalent impedance of the first impedance matching unit 211 and the equivalent impedance of the second impedance matching unit 212 to make the current amplification factor Control current gain factor When the current gain factor is equal to or close to the natural number 1, Equal to or close to the natural number 1, the equivalent impedance of the active filter device will decrease, and the compensation current injected into the three-phase line by the active filter device is likely to be injected into the three-phase line without being diverted to other bypasses, such as Figure 3 The circuit model shown, at this time, the current i L Will reduce, the actual compensation current i injected into the three-phase line inj will become larger, so that the target noise current can be offset reliably and accurately, improving the noise reduction effect.

[0037] See also 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, 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 end of the first capacitor C1 and the other end of the second capacitor C2 are both electrically connected to the series node N1, and the first equivalent impedance is the equivalent impedance composed of the first resistor R1, the first capacitor C1 and the second capacitor C2.

[0038] Please continue reading 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, 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 end of the third capacitor C3 and the other end of the fourth capacitor C4 are both electrically connected to the controller 22, and the second equivalent impedance is the equivalent impedance composed of the second resistor R2, the third capacitor C3 and the fourth capacitor C4.

[0039] See also Figure 5 The current injection circuit 23 includes a transformer 231 and three current injection units, wherein the three current injection units are a first current injection unit 232 , a second current injection unit 233 and a third current injection unit 234 .

[0040] like 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 electrically connected to three current injection units respectively, and the other end of the secondary winding 2312 is grounded.

[0041] like Figure 5 As 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, and the other end of the Y capacitor unit 2302 is grounded.

[0042] 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, and the other end of the injection capacitor unit 2301 is electrically connected to one end of the Y capacitor unit 2302 and the first phase coil A respectively, and the other end of the Y capacitor unit 2302 is grounded.

[0043] 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, and the other end of the injection capacitor unit 2301 is electrically connected to one end of the Y capacitor unit 2302 and the second phase coil B respectively, and the other end of the Y capacitor unit 2302 is grounded.

[0044] 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, and the other end of the injection capacitor unit 2301 is electrically connected to one end of the Y capacitor unit 2302 and the third phase coil C respectively, and the other end of the Y capacitor unit 2302 is grounded.

[0045] Intrinsic coefficient Constrained by the first coupling coefficient of the transformer 231, the second coupling coefficient between the collection coil and the three-phase coil, the first turns ratio of the transformer, and the second turns ratio between the collection coil and the three-phase coil, for example, the inherent coefficient can be obtained according to the following formula: :

[0046] is the first coupling coefficient, is the second coupling coefficient, is the first turns ratio, is the second turns ratio.

[0047] The minimum induction frequency of the noise sensing module is 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. For example, the minimum induction frequency can be obtained according to the following formula:

[0048] is the minimum induction frequency, is the input impedance, is the first turns ratio, is the second turns ratio, is the self-inductance coefficient, is the first coupling coefficient, is the second coupling coefficient.

[0049] See also Figure 6 The current injection circuit 23 further includes a voltage protection circuit 235, which is electrically connected to both ends of the primary winding 2311. When an abnormally high voltage appears in the active filter device, the voltage protection circuit 235 can prevent the transformer 231 from having an excessive voltage and thus damaging the transformer 231.

[0050] Please combine Figure 4 The voltage protection circuit 235 includes a transient voltage suppression diode TVS, which is electrically connected to both ends of the primary winding 2311. When a transient high voltage appears in the active filter device, and the high voltage exceeds the breakdown voltage of the transient voltage suppression diode TVS, the transient voltage suppression diode TVS will quickly turn on to form a low impedance path, and guide the instantaneous large current to the ground, thereby limiting the voltage at both ends of the transformer 231, so that the transformer 231 is protected from the impact of excessive voltage. When the transient voltage disappears, the transient voltage suppression diode TVS will return to a high impedance state, and will not affect the normal operation of the active filter device.

[0051] In order to explain in detail the working principle of the active filter device provided in the embodiment of the present application, the embodiment of the present application is combined with Figure 4 and Figure 7 The detailed description is as follows: The noise sensing module 100 is arranged on a main circuit in which a three-phase AC power source provides power to a load. The AC power source 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 to obtain a current signal.

[0052] The current signal induced by the collection coil 12 is transmitted to the first impedance matching unit 211 and the second impedance matching unit 212 in sequence through the terminal S+ and the terminal S−, and finally transmitted to the controller 22 .

[0053] The controller 22 analyzes the target noise current based on the current signal, generates a compensation current with a phase opposite to the target noise current based on the target noise current, and sequentially passes the compensation current through the transformer 231, the injection capacitor unit of the corresponding phase and the phase coil of the corresponding phase, thereby completing the process of injecting the compensation current into the three-phase line.

[0054] The embodiment of the present application configures the first equivalent impedance of the first impedance matching unit 211 and the equivalent impedance of the second impedance matching unit 212 to make the current amplification factor Control current gain factor When the current gain factor is equal to or close to the natural number 1, Equal to or close to the natural number 1, the equivalent impedance of the active filter device It will decrease, and the compensation current injected into the three-phase line by the active filter device is easily injected into the three-phase line instead of being diverted to other bypasses. Therefore, most or all of the compensation current output by the controller 22 is injected into the three-phase line, which can reliably and accurately offset the target noise current and improve the noise reduction effect.

[0055] In some embodiments, see Figure 8 The injection capacitor unit 2301 includes a plurality of injection capacitor subunits 81 connected in parallel, each of which includes a switch SW and an injection capacitor SC connected in series. The Y capacitor unit 2302 includes a Y capacitor, one end of which is electrically connected to the injection capacitor unit 2301, and the other end of which is grounded.

[0056] The inventors have discovered that the bandwidth of the active filter device provided by the related art is fixed. When the noise frequency exceeds the bandwidth of the active filter device and the frequency of the compensation current output by the active filter device does not fall within the bandwidth of the active filter device, the compensation current is easily attenuated, resulting in the compensation current being unable to effectively offset the noise current and the noise suppression effect being poor.

[0057] In an embodiment of the present application, the controller 22 is used to select a target number of injection capacitor sub-units, determine a target noise frequency based on a target noise current, and generate a compensation current based on the target noise frequency, so that the injection frequency of the compensation current applied to the target phase line 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.

[0058] The target phase line is the phase line corresponding to the selected injection capacitor subunit. For example, if the selected injection capacitor subunit corresponds to the A phase line, the target phase line is the A phase line. Similarly, if the selected injection capacitor subunit corresponds to the B phase line, the target phase line is the B phase line. If the selected injection capacitor subunit corresponds to the C phase line, the target phase line is the C phase line.

[0059] based on Figure 4 and Figure 7 The circuit structure shown in the figure, the expression of the minimum injection frequency provided by the embodiment of the present application is:

[0060] is the minimum injection frequency, is the first turns ratio, is the self-inductance of the transformer, is the total capacitance of the selected injection capacitor subunit, is the Y capacitor corresponding to the target phase line.

[0061] The expression of the maximum injection frequency provided in the embodiment of the present application is:

[0062] is the minimum injection frequency, is the first coupling coefficient.

[0063] It can be seen from the above two equations that both the minimum injection frequency and the maximum injection frequency are related to the total capacitance value of the selected injection capacitor subunit.

[0064] If the acquisition coil 12 collects the current signal of the A-phase line, the controller 22 selects the 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 expanded to at least include various noise frequencies, so that the compensation current output by the controller can be compatible with various noise reduction situations and suppress various noise currents.

[0065] The controller 22 parses the target noise current from the A-phase line from the current signal, and then 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 of the compensation current applied to the A-phase line under the action of the transformer, the selected injection capacitor subunit and the Y capacitor corresponding to the A-phase line is consistent with the target noise frequency.

[0066] If the acquisition coil 12 acquires the current signal of the B-phase line, the controller 22 selects the target number of injection capacitor subunits in the injection capacitor unit 2301 of the first current injection unit 232. The controller 22 parses 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 the compensation current based on the target noise frequency, so that the injection frequency of the compensation current applied to the B-phase line is consistent with the target noise frequency under the action of the transformer, the selected injection capacitor subunit and the Y capacitor corresponding to the B-phase line.

[0067] If the acquisition coil 12 acquires the current signal of the C-phase line, the controller 22 selects the target number of injection capacitor subunits in the injection capacitor unit 2301 of the first current injection unit 232. The controller 22 parses 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 the compensation current based on the target noise frequency, so that the injection frequency of the compensation current applied to the C-phase line is consistent with the target noise frequency under the action of the transformer, the selected injection capacitor subunit and the Y capacitor corresponding to the C-phase line.

[0068] In some embodiments, the controller 22 selects the target number of injection capacitor sub-units, including: obtaining a noise current table, the noise current table includes multiple noise currents detected in the historical noise reduction process, finding the maximum noise frequency and the minimum noise frequency based on the noise current table, determining the target number of switches based on the maximum noise frequency and the minimum noise frequency, the target number of switches is the number of switches that need to be closed, and selecting the injection capacitor sub-unit whose number is consistent with the target number of switches.

[0069] The historical noise reduction process refers to the process in which the active filter device generates a compensation current to offset the noise current in the past. The controller 22 records the noise frequency of each noise current in the noise current table during each noise reduction process. The controller 22 compares any two noise frequencies in the noise current table to find out the maximum noise frequency and the minimum noise frequency.

[0070] The controller determines the target switch quantity based on the maximum noise frequency and the minimum noise frequency, including: determining a first candidate quantity based on the maximum noise frequency and the capacitance value of a single injection capacitor, the first candidate quantity being the quantity of switches turned on when the maximum injection frequency is greater than the maximum noise frequency, and the maximum noise frequency is inversely proportional to the first candidate quantity; determining a second candidate quantity based on the minimum noise frequency and the capacitance value of a single injection capacitor, the second candidate quantity being the quantity of switches turned on when the minimum injection frequency is less than the minimum noise frequency, and the minimum noise frequency is inversely proportional to the second candidate quantity; and selecting the minimum candidate quantity between the first candidate quantity and the second candidate quantity as the target switch quantity.

[0071] For example, the embodiment of the present application finds the minimum noise frequency from the noise current table as , the maximum noise frequency is , we have the following expression:

[0072]

[0073]

[0074]

[0075] is the total capacitance value of the capacitor subunit that needs to be gated and injected corresponding to the minimum noise frequency, is the total capacitance value of the capacitor subunit that needs to be gated and injected corresponding to the maximum noise frequency, is the capacitance value of a single injection capacitor, is the first candidate number, is the second candidate number.

[0076] In the embodiment of the present application, the first candidate number The second candidate number Select the minimum candidate number as the target switch number, for example, the first candidate number is 2, the second candidate number is 1, then the target number of switches is 1. In this way, the embodiment of the present application can adaptively adjust the bandwidth to adapt to the noise frequency of various noise currents, thereby ensuring that various noise currents can be suppressed reliably and accurately.

[0077] Based on the active filtering devices provided in the above-mentioned embodiments, an embodiment of the present application further provides a vehicle-mounted device, which includes the active filtering device provided in the above-mentioned implementation manner.

[0078] It should be noted that the preferred embodiments of the present application are given in the specification and drawings of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. These embodiments are not used as additional limitations on the content of the present application. The purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the description of the present application; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the present application.

Claims

1. An active filter device, characterized in that: include: A noise sensing module, comprising a three-phase coil, a collection coil and a magnetic core, wherein the three-phase coil and the collection coil are respectively wound on the magnetic core, the three-phase coil is configured to transmit a three-phase alternating current power supply, and the collection coil is configured to sense a current signal flowing through the three-phase coil; An impedance matching circuit, comprising a first impedance matching unit and a second impedance matching unit, wherein the first impedance matching unit and the second impedance matching unit are electrically connected to a preset series node, and the first impedance matching unit is electrically connected to the acquisition 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 having 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 to the three-phase line of the three-phase AC power source, configured to inject the compensation current into the three-phase line to offset the target noise current; Among them, 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 coefficient of the compensation current is the product of a preset inherent coefficient and the current amplification factor, and the current amplification factor can make the current gain coefficient equal to the natural number 1.

2. The active filter device according to claim 1, characterized in that: 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, the other end of the first capacitor and the other end of the second capacitor are both electrically connected to the series node, and the first equivalent impedance is an equivalent impedance composed of the first resistor, the first capacitor and the second capacitor.

3. The active filter 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, the other end of the third capacitor and the other end of the fourth capacitor are both electrically connected to the controller, and the second equivalent impedance is an equivalent impedance composed of the second resistor, the third capacitor and the fourth capacitor.

4. The active filter device according to any one of claims 1 to 3, characterized in that: The current injection circuit includes a transformer and three current injection units; The transformer comprises 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 current injection units respectively, and the other end of the secondary winding is grounded; Each current injection unit comprises 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 of the three-phase coil, and the other end of the Y capacitor unit is grounded; The natural coefficient is constrained by a first coupling coefficient of the transformer, a second coupling coefficient between the acquisition coil and the three-phase coil, a first turns ratio of the transformer, and a second turns ratio between the acquisition coil and the three-phase coil.

5. The active filter device according to claim 4, characterized in that: The injection capacitor unit includes a plurality of injection capacitor sub-units connected in parallel, and each of the injection capacitor sub-units 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: gating a target number of injection capacitor subunits; determining a target noise frequency based on the target noise current; A compensation current is generated based on the target noise frequency, so that the injection frequency of the compensation current applied to the target phase line under the action of the transformer, the selected injection capacitor subunit 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 subunit.

6. The active filter device according to claim 5, characterized in that: The gated target number of injection capacitor subunits includes: Obtaining a noise current table, the noise current table including a plurality of noise currents detected during a historical noise reduction process; Find out the maximum noise frequency and the minimum noise frequency based on the noise current table; Determine a target number of switches based on the maximum noise frequency and the minimum noise frequency, the target number of switches being the number of switches that need to be closed; The number of injection capacitor subunits that is consistent with the target switch number is selected.

7. The active filter device according to claim 6, characterized in that: The controller determines a target switching quantity 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, the first candidate number being the number of switches that are turned on 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, the second candidate number being the number of switches that are turned on 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; A minimum candidate number is selected between the first candidate number and the second candidate number as the target switch number.

8. The active filter 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 two ends of the primary winding.

9. The active filter device according to claim 4, characterized in that: The minimum induction frequency of the noise sensing module is 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: include: An active filter device as claimed in any one of claims 1 to 9.

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