A floating four-winding common-mode inductance active enhancement circuit

Abstract

The application belongs to the technical field of power electronics electromagnetic compatibility, and relates to a floating ground type four-winding common-mode inductor active enhancement circuit which comprises a four-winding common-mode inductor and two-way operational amplifier circuits; a main power winding is connected with a power supply and a converter, a third winding and a fourth winding are respectively connected with a first operational amplifier circuit and a second operational amplifier circuit, and the two-way circuit midpoints are interconnected. The operational amplifier circuit is composed of an operational amplifier, a resistor, a capacitor and an auxiliary inductor L0 with a magnetic core, the operational amplifier is connected with an independent floating ground power supply, and the power supply equipotential point is used as a reference without external grounding. The application improves common-mode equivalent impedance through a symmetrical operational amplifier circuit, compensates high-frequency non-ideal characteristics of the inductor through L0, is suitable for non-grounded floating ground equipment such as photovoltaic and airborne equipment, and suppresses common-mode electromagnetic interference in a wide frequency range.

Description

Technical Field

[0001] This invention belongs to the field of power electronics electromagnetic compatibility technology, specifically relating to a floating-ground four-winding common-mode inductor active enhancement circuit, which is suitable for common-mode electromagnetic interference suppression in floating-ground power electronic devices. Background Technology

[0002] Power electronic equipment is rapidly developing towards higher frequencies, smaller sizes, and higher efficiency. The widespread adoption of wide-bandgap semiconductors has further increased the switching frequency of devices, making electromagnetic interference (EMI) problems in systems increasingly severe. Simultaneously, increasingly stringent electromagnetic compatibility (EMC) regulations place higher demands on equipment noise suppression performance, making EMI filtering technology crucial for ensuring stable and compliant equipment operation. Traditional passive EMI filters rely on discrete inductors and capacitors to form the filter network, which suffers from problems such as a large number of components, large size, significant influence from high-frequency parasitic parameters, and frequent changes in core parameters, making it difficult to simultaneously meet the needs of equipment miniaturization and wide-bandwidth, high-precision filtering. Therefore, active EMI filtering technology, with its advantages of small size and adjustable filtering performance, is gradually becoming the mainstream research direction for high-frequency electromagnetic interference suppression.

[0003] However, many floating power electronic devices, such as traditional photovoltaic optimizers, airborne equipment, and portable power supplies, lack a physical grounding terminal and a fixed electrical reference point. Existing active EMI filters rely on grounding to the earth or the equipment chassis, making them unsuitable for floating-ground operation and severely limiting their application scenarios. On the other hand, inductor enhancement circuits are a preferred solution for active filtering due to their simple structure, low cost, and ability to improve common-mode equivalent impedance. However, existing technologies still have significant shortcomings: First, the common-mode inductor is treated as an ideal device during modeling, ignoring the non-ideal impedance characteristics caused by high-frequency permeability variations, eddy current losses, and winding parasitic parameters, leading to impedance matching deviations and a significant reduction in the active enhancement effect. Second, the limited number of adjustable parameters and low design freedom make it impossible to finely optimize the equivalent impedance, hindering the adaptation to various operating conditions and wide-frequency filtering requirements.

[0004] Therefore, a common-mode inductor active enhancement circuit is needed to meet the application requirements of floating ground operation, high-frequency and high-precision filtering, and flexible parameter adjustment, which are difficult to achieve simultaneously with existing technologies. Summary of the Invention

[0005] This invention provides the following technical solution: a floating-ground type four-winding common-mode inductor active enhancement circuit, comprising a four-winding common-mode inductor, a first operational amplifier circuit, and a second operational amplifier circuit. The four-winding common-mode inductor includes a first winding L... cm1 Second winding L cm2 Third winding L cm3 Fourth winding L cm4 First winding L cm1 Second winding L cm2The main power circuit is connected in series between the power supply and the converter; the first winding L cm1 Second winding L cm2 The terminal with the same name is close to the power supply; the third winding L cm3 The first operational amplifier circuit is connected at both ends, and the fourth winding L cm4 The two ends are connected to the second operational amplifier circuit.

[0006] The first operational amplifier circuit includes operational amplifier A1 and resistor R. p R n Auxiliary inductor L0; the third winding L is connected in series with the non-inverting input of operational amplifier A1. cm3 The non-identical terminal and auxiliary inductor L0 are connected to the inverting input of operational amplifier A1, and resistor R is connected to the inverting input. p The two ends are connected to the non-inverting input and output terminals of operational amplifier A1, respectively, and resistor R... n The two ends are connected to the inverting input and output terminals of operational amplifier A1, respectively. The second operational amplifier circuit includes operational amplifier A2 and resistor R. po R ng R f R s Capacitor C s The fourth winding L is connected in series with the non-inverting input of operational amplifier A2. cm4 Non-identical terminals, resistor R ng Then connect to the inverting input of operational amplifier A2, resistor R po The two ends are connected to the non-inverting input and output terminals of operational amplifier A2, respectively, and resistor R... f The two ends of the resistor R are connected to the inverting input and output terminals of operational amplifier A2, respectively; s Capacitor C s The two ends of the series connection are respectively connected to resistors R. f The two ends. The fourth winding L cm4 The same terminal, resistor R ng The connection node connects to the third winding L cm3 The connection node of the same name terminal and the auxiliary inductor L0 is connected to the equipotential point of the operational amplifier power supply.

[0007] Operational amplifiers A1 and A2 share a single floating ground power supply. The reference potential of the floating ground power supply is the equipotential point of the power supply, eliminating the need for an external physical ground. The auxiliary inductor L0 is made of the same magnetic ring material as the core of the four-winding common-mode inductor.

[0008] Preferably, the four-winding common-mode inductor satisfies the winding symmetry condition as follows: the self-impedance of the first winding and the second winding are equal, the self-impedance of the third winding and the fourth winding are equal, and the mutual impedance between the first winding and the third winding, and between the first winding and the fourth winding are all equal.

[0009] Preferably, the circuit impedance of the common-mode inductor active enhancement circuit satisfies the following constraints: ;in The equivalent impedance of the operational amplifier circuit on the third winding side. The equivalent impedance of the operational amplifier circuit on the fourth winding side. The third winding's self-impedance; the overall common-mode impedance when this condition is met. Greater than the original common-mode impedance .

[0010] More preferably, the equivalent impedance on the third winding side is: , For inductance The impedance; the equivalent impedance on the fourth winding side is , s It is a complex frequency operator.

[0011] Preferably, the common-mode inductor active enhancement circuit has six independently adjustable parameters with degrees of freedom, and the independently adjustable parameters are as follows: Ratio, Auxiliary Inductance , Product, resistance R f Capacitor C s Resistance R s The common-mode inductor active enhancement circuit achieves precise optimization of wide-frequency common-mode impedance by adjusting six parameters.

[0012] Preferably, the first operational amplifier circuit and the second operational amplifier circuit are arranged symmetrically back to back, thereby providing active impedance enhancement to the third winding and the fourth winding, respectively.

[0013] Preferably, the operational amplifier power supply reference plane can be selected as either floating mode or grounded mode; the floating mode is suitable for photovoltaic optimizers, portable power supplies, and airborne floating power electronic devices without physical grounding.

[0014] Preferably, the auxiliary inductor It is used to compensate for the non-ideal complex impedance characteristics caused by the high-frequency change of magnetic permeability, eddy current loss, and winding distributed capacitance of a four-winding common-mode inductor, thereby broadening the effective filtering bandwidth of the circuit.

[0015] Preferably, after the circuit is connected to the main circuit, the common-mode impedance expression is:

[0016] In the formula: , , , These are the self-impedances of the four windings, respectively. , , , , These are the mutual impedances between windings.

[0017] Preferably, the third winding and the fourth winding have the same number of turns.

[0018] The beneficial effects of this invention are: 1. This invention, by configuring operational amplifier circuits at the ends of the third and fourth windings of a four-winding common-mode inductor, and relying on the positive and negative feedback collaborative working mechanism of the operational amplifiers, can effectively improve the overall equivalent impedance of the common-mode inductor. When specific impedance matching conditions are met, the common-mode impedance can be significantly enhanced, significantly reducing the common-mode current in the line, achieving deep suppression of common-mode electromagnetic noise in power electronic devices, and effectively improving the electromagnetic compatibility performance of the equipment.

[0019] 2. This invention uses a magnetic ring made of the same material as the common-mode inductor core to prepare the auxiliary inductor. L 0 can accurately compensate for the non-ideal impedance defects of common-mode inductors caused by frequency-varying permeability characteristics and parasitic parameters under high-frequency operating conditions, improve the impedance matching deviation problem in the high-frequency band, and enable the active enhancement circuit to maintain stable and excellent filtering performance in a wide frequency range. It effectively solves the technical problems of high-frequency filtering effect attenuation and limited enhancement effect of traditional active filter circuits.

[0020] 3. This invention adopts an operational amplifier reference plane floating ground structure design, which can work stably without being connected to a physical ground. It completely gets rid of the application limitations of traditional active filter circuits that rely on grounding terminals. It can be perfectly adapted to floating ground power electronic devices without physical grounding terminals, such as photovoltaic optimizers, portable power supplies, and airborne equipment, which greatly expands the applicable scenarios and engineering application scope of active common mode filter circuits. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a floating-ground type four-winding common-mode inductor active enhancement circuit according to the present invention; Figure 2 This is a comparison diagram of noise before and after using the circuit of the present invention. Detailed Implementation

[0022] The related technologies of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figures 1-2As shown, the voltage-current relationship of the four-winding common-mode inductor active enhancement circuit of this embodiment has the following expression.

[0024]

[0025] in For the self-impedance of a single winding, Let be the mutual impedance of the windings, which is a complex number in the conducted interference frequency band. When the third and fourth windings are open-circuited, the common-mode impedance can be calculated as:

[0026] After the operational amplifier circuit of this invention is connected to the two ends of the third and fourth windings, when the op-amp is working normally, the equivalent impedance of the circuit connected to the equivalent inductance Lcm3 of the third winding is:

[0027] in, For inductance The impedance of a common-mode inductor is non-ideal due to factors such as the frequency-varying permeability of the core material, eddy current losses, winding distributed capacitance, and parasitic parameters. To achieve the best effect of the active enhancement circuit, the impedance characteristics of the common-mode inductor at high frequencies need to be optimized. The magnetic ring material must be selected to match the material of the common-mode inductor core.

[0028] The equivalent impedance of the circuit connected to the equivalent inductance Lcm4 of the fourth winding is:

[0029] The common-mode impedance expression after applying this circuit is as follows:

[0030] Precise design is achieved through actual measurement of the impedance of each winding of the common-mode inductor. Since the first and second windings of the common-mode inductor are symmetrical, , , Furthermore, to simplify the design and ensure that the third and fourth windings have the same number of turns, the third and fourth windings also possess symmetry, i.e. , Therefore, only measurement is required. , as well as That's all.

[0031] When satisfied hour, .

[0032] In this embodiment, the reference plane can be either floating or grounded; the circuits connected to the third winding and the fourth winding can be interchanged.

[0033] In summary, the floating-ground four-winding common-mode inductor active enhancement circuit of the present invention, through innovative floating-ground reference design, symmetrical winding operational amplifier circuit enhancement structure and auxiliary inductor compensation scheme, solves three major technical pain points of traditional active filter circuits that cannot adapt to floating-ground operating scenarios, high-frequency non-ideal impedance leading to attenuation of active enhancement effect, and insufficient design freedom making it difficult to achieve wide-frequency domain accurate optimization. It can effectively improve the common-mode electromagnetic interference suppression capability of floating-ground power electronic devices and has good engineering application prospects in scenarios without physical grounding, such as photovoltaic optimizers, portable power supplies, and airborne power electronic systems.

[0034] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A floating-ground type four-winding common-mode inductor active enhancement circuit, characterized in that, Includes a four-winding common-mode inductor, a first operational amplifier circuit, and a second operational amplifier circuit; The four-winding common-mode inductor includes a first winding L cm1 Second winding L cm2 Third winding L cm3 Fourth winding L cm4 The first winding L cm1 Second winding L cm2 The main power circuit is connected in series between the power supply and the converter; the first winding L cm1 Second winding L cm2 The terminal with the same name is close to the power supply; the third winding L cm3 The first operational amplifier circuit is connected at both ends, and the fourth winding L cm4 The two ends are connected to the second operational amplifier circuit; The first operational amplifier circuit includes operational amplifier A1 and resistor R. p R n Auxiliary inductor L0; the operational amplifier A1 has a third winding L connected in series at its non-inverting input terminal. cm3 The non-identical terminal and the auxiliary inductor L0 are connected to the inverting input of the operational amplifier A1, and the resistor R... p The two ends of the resistor R are connected to the non-inverting input and output terminals of operational amplifier A1, respectively. n The two ends are connected to the inverting input and output terminals of operational amplifier A1, respectively; The second operational amplifier circuit includes operational amplifier A2 and resistor R. po R ng R f R s Capacitor C s The operational amplifier A2's non-inverting input terminal is sequentially connected in series with the fourth winding L. cm4 Non-identical terminals, resistor R ng The resistor R is then connected to the inverting input of operational amplifier A2. po The two ends of the resistor R are connected to the non-inverting input and output terminals of operational amplifier A2, respectively. f The two ends of the resistor R are respectively connected to the inverting input and output of operational amplifier A2; s Capacitor C s The two ends of the series connection are respectively connected to resistors R. f The two ends; The fourth winding L cm4 The same terminal, resistor R ng The connection node connects to the third winding L cm3 The connection node of the same name terminal and auxiliary inductor L0, and this node is connected to the equipotential point of the operational amplifier power supply; The operational amplifiers A1 and A2 share a common floating ground power supply. The reference potential of the operational amplifiers of the floating ground power supply is the equipotential point of the power supply, and no external physical ground is required. The auxiliary inductor L0 is made of the same magnetic ring material as the core of the four-winding common-mode inductor.

2. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, The four-winding common-mode inductor satisfies the winding symmetry condition as follows: the self-impedance of the first winding and the second winding are equal, the self-impedance of the third winding and the fourth winding are equal, and the mutual impedance between the first winding and the third winding, and between the first winding and the fourth winding are all equal.

3. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, The circuit impedance of the common-mode inductor active enhancement circuit satisfies the following constraints: ;in The equivalent impedance of the operational amplifier circuit on the third winding side. The equivalent impedance of the operational amplifier circuit on the fourth winding side. The third winding's self-impedance; the overall common-mode impedance when this condition is met. Greater than the original common-mode impedance .

4. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 3, characterized in that, The equivalent impedance on the third winding side is: , Inductor The impedance; the equivalent impedance of the fourth winding side is , s It is a complex frequency operator.

5. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, The common-mode inductor active enhancement circuit has six independently adjustable parameters with degrees of freedom. These independently adjustable parameters are as follows: Ratio, Auxiliary Inductance , Product, resistance R f Capacitor C s Resistance R s The common-mode inductor active enhancement circuit achieves precise optimization of wide-frequency common-mode impedance by adjusting six parameters.

6. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, The first operational amplifier circuit and the second operational amplifier circuit are arranged symmetrically back to back, which respectively enhance the active impedance of the third winding and the fourth winding.

7. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, The operational amplifier power supply reference plane can be selected in either floating or grounded mode; the floating mode is suitable for photovoltaic optimizers, portable power supplies, and airborne floating power electronic devices without physical grounding.

8. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, The auxiliary inductor It is used to compensate for the non-ideal complex impedance characteristics caused by the high-frequency change of magnetic permeability, eddy current loss, and winding distributed capacitance of a four-winding common-mode inductor, thereby broadening the effective filtering bandwidth of the circuit.

9. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, After the circuit is connected to the main circuit, the common-mode impedance expression is: In the formula: , , , These are the self-impedances of the four windings, respectively. , , , , These are the mutual impedances between windings.

10. The floating-ground four-winding common-mode inductor active enhancement circuit according to claim 1, characterized in that, The third winding and the fourth winding have the same number of turns.

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