287 results about "Leakage inductance" patented technology

The present invention relates to the technical field of transformer fault detection. Disclosed is a transformer early fault diagnosis method based on the difference between virtual and actual winding leakage magnetic field waveforms, comprising: collecting leakage magnetic field information of a non-ideal winding structure transformer by means of fiber-optic magnetic field sensors; decomposing a winding of the non-ideal winding structure transformer into a plurality of regular windings; superposing leakage magnetic fields at the ends of a plurality of regular windings to obtain a non-ideal winding end leakage magnetic field; calculating a leakage flux matrix leakage inductance parameter and a leakage magnetic field output matrix parameter on the basis of the non-ideal winding end leakage magnetic field; establishing a circuit-leakage magnetic field multi-state digital model corresponding to the transformer; and using the difference between an actual transformer leakage magnetic field waveform and a digital transformer model virtual leakage magnetic field waveform as a fault characteristic quantity, completing threshold calculation and early fault sensitivity verification, forming a waveform difference-based early fault diagnosis criterion, and determining a fault position. The present invention can achieve quick and sensitive diagnosis of early faults of transformer windings and improves device operating reliability.

The invention belongs to the technical field of nuclear power, and particularly relates to a ground capacitance measurement method based on series capacitance and high-frequency signal injection. In order to solve the problem that a traditional signal injection method cannot accurately calculate the ground capacitance level of a power distribution network, the invention provides a ground capacitance measurement method based on a series capacitor and high-frequency signal injection. The leakage inductance of the voltage transformer is accurately measured by injecting the high-frequency signal, so that a resonance point is convenient to find during frequency sweeping, and the resonance point measured during frequency sweeping is more accurate.

The application provides a high-frequency circulating current calculation method for a motor simulator cascaded coupling parallel structure, comprising the following steps: establishing an equivalent decoupling circuit model of each branch in the cascaded coupling parallel structure based on the voltage relationship of each branch in the motor simulator cascaded coupling parallel structure, wherein the equivalent decoupling circuit of each branch comprises an equivalent voltage source and an equivalent leakage inductance connected in series, and the equivalent leakage inductance is determined based on the self-inductance and mutual inductance of each branch choke; dividing a plurality of duty cycle intervals between 0 and 1, and the number of duty cycle intervals is equal to the number of branches in the cascaded coupling parallel structure; and using the equivalent decoupling circuit model to calculate the high-frequency circulating current of each branch when the duty cycle of the modulation signal of the motor simulator is in each duty cycle interval. The method provided by the application can accurately calculate the high-frequency circulating current of the motor simulator cascaded coupling parallel structure, and provides effective support for the targeted design of a high-frequency circulating current suppression scheme.

The invention provides a current stress optimization method and system for an isolated bidirectional three-phase energy storage converter, and relates to the technical field of power conversion. Firstly, Fourier series analysis is carried out on primary and secondary side voltages of a high-frequency transformer, and leakage inductance current and active power are calculated accordingly; carrying out per-unit processing on the active power and the square of the primary side current, and obtaining the active power and the square of the peak current under the fundamental component based on a per-unit processing result; then, with the minimum square of the peak current as an optimization target and the transmission power under the fundamental component as a constraint, constructing and solving a current stress optimization model so as to obtain an optimal matrix converter parameter; and finally, performing current stress optimization control based on the optimal parameters to reduce the current stress. According to the method, the current stress is remarkably reduced while the set transmission power requirement is met, the direct current side dynamic response is improved, and the converter performance is improved.

A method for operating a switching power converter to reduce ripple current magnitude includes (a) controlling duty cycle of a plurality power stages of the switching power converter to regulate at least one parameter of the switching power converter, each power stage including a respective power transformer, and (b) controlling an injection stage of the switching power converter to reduce voltage across leakage inductance of each power transformer, the injection stage including an injection transformer that is electrically coupled to a respective secondary winding of each power transformer.

The application discloses a bidirectional DCDC circuit and a photovoltaic energy storage inverter. The photovoltaic energy storage inverter is used for connecting a photovoltaic module, a battery and an alternating current end. The bidirectional DCDC circuit comprises a first direct current end, a second direct current end, a transformer, a first full-bridge circuit connected between the first direct current end and a primary side of the transformer, a second full-bridge circuit connected between a secondary side of the transformer and the second direct current end and a first capacitor. The first full-bridge circuit is directly connected with the primary side of the transformer and / or the second full-bridge circuit is directly connected with the secondary side of the transformer. The first capacitor is located between the second full-bridge circuit and the second direct current end and is connected with positive and negative poles of the second direct current end. The bidirectional DCDC circuit provided in the application uses leakage inductance of the primary side of the transformer and the first capacitor to form an LC resonant circuit instead of an LC resonant circuit arranged at two ends of the transformer, so that the function of the resonant circuit is realized while the number and volume of electrical elements of a topological structure are reduced, thereby reducing the cost.

The application relates to the technical field of switching power supply, and discloses a bridge type low-stress passive soft switching boost power factor correction circuit, which comprises a direct current input power supply, a main power switching tube, an output filter capacitor and a coupling inductor comprising a primary side and a secondary side; a passive soft switching buffer network is connected to a main circuit of the circuit, the network comprises a diode full-bridge structure and a buffer capacitor, and the leakage inductance of the secondary side of the coupling inductor is connected between the midpoints of two bridge arms of the full-bridge structure; the application utilizes the ratio difference of the coupling inductor to generate a forward potential difference, drives the buffer capacitor to reversely charge to establish a negative voltage, and further provides a discharge circuit for the parasitic junction capacitance of the main power switching tube, so that zero voltage turn-on is realized, and high-frequency switching loss is reduced; meanwhile, the highest voltage stress of the semiconductor device is clamped in the range of the direct current output voltage through the potential restriction of the full-bridge network. The application does not need auxiliary active devices, and improves conversion efficiency and reliability while simplifying the system structure.

The invention relates to a transformer leakage inductance calculation method and device and computer equipment. The method comprises the following steps: acquiring magnetic induction intensity and vector magnetic potential of any point in an iron core window; obtaining magnetic field energy in an iron core window area based on the magnetic induction intensity and geometric parameters of the iron core window; based on the vector magnetic potential and the cross section size of the winding area, obtaining interaction energy of the current and the vector magnetic potential in the winding area; on the basis of the interaction energy and the magnetic field energy, magnetic leakage energy stored by a unit length winding is obtained; the leakage inductance of the transformer is obtained based on the total leakage flux energy of the winding and the winding current of the low-frequency equivalent circuit, and the total leakage flux energy is obtained through calculation based on the leakage flux energy stored by the winding per unit length and the winding length.

The invention discloses a transformer capable of suppressing common-mode interference and a booster circuit, and belongs to the technical field of power electronic converters, the transformer comprises a magnetic core, a primary winding and a secondary winding, the primary winding and the secondary winding are formed by winding multiple layers of coaxial cables, shielding conductors of the primary winding and the secondary winding are configured to have the same number of winding turns and winding direction, the structure of the transformer is applied to a staggered winding mode and is connected to a static potential point, so that the potential distribution between the transformer and the static potential point is consistent, the voltage difference on a distributed capacitor is close to zero, common-mode conducted interference is fundamentally inhibited, the transformer structure is also applicable to the staggered winding mode, and the process can be simplified while the leakage inductance is reduced. The booster circuit using the transformer realizes efficient and low-interference multipath isolation output.

The invention relates to the technical field of power control, in particular to a filter and leakage inductance collaborative design method of a single-stage bidirectional high-frequency isolation inverter, which comprises the following steps: acquiring basic design parameters, constructing an inverter modulation model according to a modulation strategy, and solving the model to obtain a modulation signal expression; deriving a zero-current switching current constraint condition and a zero-voltage switching current constraint condition of the switching tube based on a modulation strategy; combining the constraint condition with an inverter modulation model, and solving to obtain a soft switching constraint condition; according to the soft switching constraint condition and the value range of the modulation signal expression, determining a collaborative value range of the filter inverter side inductance and the transformer leakage inductance meeting the soft switching requirement; and selecting design parameters of inverter side inductance and transformer leakage inductance of the filter, and determining other circuit parameters of the filter according to a reactive power demand and a grid-connected harmonic standard. According to the invention, the problems of soft switching failure, loss increase and electromagnetic interference caused by parameter mismatching can be effectively suppressed.

In accordance with one embodiment, a driver is configured to adjust a phase offset of driver control signals between corresponding switches of the same phase of the primary converter and the secondary converter consistent with the target power transfer and the estimated electromagnetic circuit inductance (e.g., comprising a leakage inductance), to minimize thermal energy dissipated from the direct-current-to-direct current converter or its transformer for the sampling time interval.

This utility model discloses a drive-shielded transformer and voltage converter, belonging to the field of transformer technology. The drive-shielded transformer includes a frame, a primary winding, a secondary winding, and a magnetic core. The primary and secondary windings are sequentially wound around the frame, and a shielding layer is provided between the primary and secondary windings. The magnetic core is located at both ends of the frame. The leads of the primary winding, secondary winding, and shielding layer are connected to the pins of the frame, and the shielding layer is grounded through the pins. This drive-shielded transformer uses copper foil shielding and grounding to shield the parasitic capacitance, leakage inductance, and interference generated by the primary and secondary windings, and releases them through the grounding leads. This significantly reduces the leakage inductance and parasitic capacitance of the transformer, giving the transformer the best electromagnetic compatibility effect during operation, isolating noise and spurious waves within the operating frequency, resulting in higher power conversion efficiency and lower temperature rise during continuous operation. This transformer features small size, wide operating frequency range, and good structural assembly.

The invention provides a linearization control method and system for an energy storage system, and mainly provides a single-phase-shift frequency conversion modulation method applied to the linearization control method and system, the single-phase-shift frequency conversion modulation method is applied to a single-stage DAB type AC-DC converter, and the alternating current input voltage vac, the alternating current input current iac and the direct current output voltage Vdc of the single-stage DAB type AC-DC converter are sampled; based on the sampled alternating current input voltage vac, the alternating current input current iac and the direct current output voltage Vdc, a control variable theta is obtained through calculation; on the basis of the obtained control variable theta, at the moment when the leakage inductance peak current iLk has the maximum value, a mapping coefficient c of the leakage inductance peak current at the moment is obtained through a differential extreme value method; based on the obtained control variable theta and the mapping coefficient c, calculating to obtain a phase shift ratio D and a switching frequency fs; d = 1-c theta; fs = fa (c-c2theta); and based on the obtained phase shift ratio D and the switching frequency fs, a driving signal for single phase shift frequency conversion modulation is given.

The utility model provides an MOS tube drive power supply circuit with an MOS tube absorption loop, which comprises an upper winding, a lower winding, an RCD absorption circuit module and a mirror current source, the RCD absorption circuit module is electrically connected with the upper winding and the lower winding respectively, the mirror current source is electrically connected with the RCD absorption circuit module, and the RCD absorption circuit module is used for supplying power to the mirror current source; a peak voltage generated by leakage inductance when a transformer is closed is absorbed by a set RCD absorption circuit module, the RCD absorption circuit module rectifies and filters the absorbed current and then provides a voltage for a mirror current source, a rectification MOS tube absorption loop is ingeniously utilized to obtain a driving voltage of an isolation MOS, the circuit is simple, and the cost is low. And a VCC circuit and a VCC device can be saved to reduce the cost, thereby contributing to energy conservation, emission reduction and carbon neutralization.

The utility model discloses an integrated 60KW three-phase high-frequency transformer for a charger, which comprises two groups of transformer banks connected in series and a shell, each transformer bank comprises three single transformers, each single transformer comprises a magnetic core, a framework, a primary winding, a secondary winding and a wiring terminal, the primary winding and the secondary winding are wound on the framework, and the primary winding and the secondary winding are wound on the framework. The primary winding and the secondary winding are arranged on the framework, the magnetic cores are arranged from the two ends of the framework and are aligned, the wire starting end of the primary winding and the wire starting end of the secondary winding are both provided with wiring terminals, and the take-up end of the adjacent primary winding and the take-up end of the adjacent secondary winding are in short-circuit connection. The transformer is of a combined structure and is distributed in a flat mode, the height problem of a product is well solved, leakage inductance of a single transformer is used for replacing a resonant inductor, and the cost of a device is reduced.

Modified control scheme for a single-stage voltage converter for voltage conversion between a single-phase AC network and a DC network. This scheme involves splitting each pulse into multiple sub-pulses when using pulse-width modulated control of a full-bridge circuit. This reduces the RMS current in the leakage inductance of the voltage converter's transformer.

The embodiment of the present application discloses an isolated power converter. In the embodiment of the present application, the isolated power converter comprises a primary side circuit, a transformer and a secondary side circuit, wherein the secondary side circuit comprises a current conversion circuit and a feedback control circuit, the current conversion circuit excites the secondary side leakage inductance of the secondary side winding via a secondary side switch component in a secondary side switch network to realize current conversion, and the feedback control circuit is configured to control the switching state of the secondary side switch component in the secondary side switch network according to an output feedback signal representing an output signal. Thus, the embodiment can directly adjust the secondary side switch component in the secondary side switch network, so that the secondary side leakage inductance can serve as a power storage element, realize magnetic integration of the transformer, and thus can eliminate the feedback signal path of the primary side and the secondary side, reduce the control complexity and manufacturing cost.

The utility model discloses an LLC topology magnetic integration high-frequency transformer, which comprises a transformer framework, magnetic cores, a primary winding and a secondary winding, and is characterized in that the magnetic cores comprise a first U-shaped magnetic core, a second U-shaped magnetic core and an E-shaped magnetic core, and the first U-shaped magnetic core and the second U-shaped magnetic core are encircled in pairs to form a magnetic circuit; the E-shaped magnetic core is arranged on the side portion of the magnetic circuit and divides the magnetic circuit into a first bypass and a second bypass. The novel UUE type magnetic core is adopted, primary and secondary coupling magnetic circuits are blocked through the E-shaped middle column, the leakage inductance of the transformer is increased, and an external resonant inductor is omitted. An external resonant inductor of an LLC topological framework is omitted, the transformer structure is simplified, the process is simplified, and high-efficiency voltage conversion of the transformer is guaranteed.

The application relates to a method for designing leakage inductance and suppressing transformer impulse current by using the leakage inductance, characterized in that the method comprises the following steps: obtaining a four-dimensional feasible region of a transformer capacity arc set S and a transformer leakage inductance set by four-dimensional visualization processing respectively L lp ; obtaining a fitted B-H curve according to actual test data of a core, and converting the B-H curve into a I curve; physically modeling a no-load transformer considering the leakage inductance, and establishing a mathematical model, and solving the mathematical model to obtain a magnetic flux expression considering the leakage inductance; combining the magnetic flux expression considering the leakage inductance and the I curve, and calculating the impulse current considering the leakage inductance i , and calculating the current of multiple periods to obtain a waveform of the impulse current. The application designs the leakage inductance by using a four-dimensional visualization method, and quantitatively calculates the impulse current considering the influence of the leakage inductance on the basis of traditional qualitative analysis of the impulse current, so that the impulse current at the power-on moment of the transformer is reduced.

The application discloses a combined photovoltaic energy storage system, and belongs to the technical field of solar power generation and energy storage. The system comprises a photovoltaic input module, a high-frequency isolation power conversion module, an energy storage battery module, a grid-connected inverter output module and a control module. The high-frequency isolation power conversion module internally comprises a three-winding high-frequency transformer, realizing magnetic coupling power transmission and electrical isolation between three ports of photovoltaic input, energy storage battery and grid-connected output. The three-winding transformer has preset leakage inductance between each winding, and forms LC filter circuits with corresponding capacitors, filtering high-frequency ripples and suppressing harmonics. The control module monitors the state of each module in real time and dynamically adjusts the switching frequency and phase shift angle. The application fundamentally solves the power coupling interference and fault propagation problem in the traditional DC coupling scheme through the three-port high-frequency isolation topology, and has the advantages of high integration, high efficiency and good safety.

The utility model provides a magnetic assembly and a switching power supply. The magnetic assembly comprises a framework, a winding, a magnetic sheet and two magnetic cores which are oppositely arranged, the magnetic core comprises a cover plate, a wrapping post and at least one public post, and one end of the wrapping post and one end of the public post are connected with the cover plate; the winding comprises a primary winding and a secondary winding, and the primary winding and the secondary winding are arranged on the framework in a sleeving manner; the winding post is sleeved with the framework, a separation part is arranged on the peripheral face of the framework in a protruding mode, the primary winding and the secondary winding are separated by the separation part, an installation notch is formed in the separation part, and the magnetic sheet is arranged in the installation notch. The primary winding and the secondary winding of the magnetic assembly are separated by the separation part and the magnetic sheet, the arrangement of the magnetic sheet is beneficial to adjusting the size of leakage inductance (namely leakage inductance) of the magnetic assembly, when the magnetic assembly is applied to a switching power supply, a resonant inductor does not need to be additionally arranged, the distance between the primary winding and the secondary winding does not need to be increased, and the magnetic assembly is simple in structure and convenient to use. Therefore, no volume burden is brought to the switching power supply.

The application provides a single-stage voltage source type direct current power flow controller, which comprises the voltage V1 and V2 of a first direct current network and a second direct current network, a medium-frequency transformer T r1 The equivalent inductance L is formed by the series connection of the leakage inductance and the auxiliary inductance eq The equivalent inductance L is formed by the series connection of the leakage inductance and the auxiliary inductance The application has the forward and reverse voltage output and power flow regulation capacity, and has the wide-range interconnected direct current system power flow regulation function.

The method for modeling impedance of DAB converter based on multi-LC resonant unit and predicting high-frequency oscillation frequency comprises the following steps: step 1, measuring impedance characteristics of a high-frequency transformer and an external inductor according to a determined DAB converter topology; step 2, calculating parasitic parameters of the high-frequency transformer and the external inductor according to the measurement results of the impedance characteristics; and step 3, judging the number of high-frequency oscillation frequencies for different configurations and parameter sizes of the external inductor and the leakage inductance of the high-frequency transformer, and selecting a high-frequency oscillation frequency prediction formula to obtain a result. The frequency variation effects of the external inductor and the leakage inductance of the high-frequency transformer are comprehensively considered, the parasitic parameters are effectively extracted through accurate modeling, and the oscillation prediction formula is derived based on the transfer function, so that the deep physical mechanism of the high-frequency oscillation is revealed, and systematic and guiding theoretical basis and engineering practice support are provided for the high-frequency oscillation suppression scheme under different structural topologies and parameter combinations.

The present disclosure relates to a gate blocking control method for a converter, and a converter and a chip. The converter comprises an alternating-current side half-bridge circuit, a filter capacitor and a controller, wherein the filter capacitor is connected in parallel to an output end of the alternating-current side half-bridge circuit. The gate blocking control method for a converter is applied to a controller. The gate blocking control method for a converter comprises: in response to a gate blocking signal corresponding to a converter, acquiring the current polarity of an alternating-current side grid voltage, and controlling an alternating-current side half-bridge circuit to operate according to a target freewheeling path corresponding to the current polarity, so as to transfer leakage inductance energy to a filter capacitor. By using the gate blocking control method for a converter, the problem of voltage stress of an alternating-current side half-bridge circuit during gate blocking can be solved, thereby preventing an alternating-current side switch device from being damaged.

The invention discloses a six-phase motor torque ripple suppression method and device based on control deviation compensation, and relates to the technical field of six-phase motor fault-tolerant control, and the method comprises the steps: collecting current signals of each phase, carrying out the vector space decoupling transformation, obtaining an alpha-beta subspace current, calculating the circularity of a current vector track, and subtracting 1 from the circularity of the current vector track to obtain a circularity deviation amplitude; a gradient descent method is used to update the leakage inductance parameter of the motor at the controller side on line, and the real-time deviation compensation voltage is calculated and superposed with the real-time control voltage to obtain the deviation compensation control voltage. The roundness of an alpha-beta subspace current vector track is introduced to serve as a torque ripple evaluation index, leakage inductance parameters which are difficult to measure and change along with working conditions are subjected to online self-adaptive updating by adopting a gradient descent method, compensation failure caused by inaccurate parameters is avoided, and the parameters are applied to a zero-sequence subspace to offset control deviation, so that the torque ripple evaluation accuracy is improved. Second harmonic current caused by control deviation can be effectively suppressed, torque ripple is remarkably reduced, and the stability and output quality of fault-tolerant operation of the motor are improved.

The application relates to a transformer for a flyback switching power supply and the flyback switching power supply, two of the first primary winding, the second primary winding and the third primary winding of the transformer are connected in parallel and connected with the other in series to form a primary winding unit, the primary winding unit is connected between the static point pin and the dynamic point pin of the transformer, and a Y-shaped winding method or an inverted Y-shaped winding method with the dynamic point pin as a reference point can be formed; when the inverted Y-shaped winding method is adopted, the magnetic field generated by the primary winding is distributed in an axial symmetry in the winding window, the leakage inductance can be obviously reduced, and the power supply efficiency can be improved; the Y-shaped winding method or the inverted Y-shaped winding method can distribute more turns in the primary winding which is not connected in parallel, the number of the windings connected in parallel is reduced, and the parasitic capacitance of the secondary winding can be reduced.

The invention relates to the technical field of DC-DC conversion, and discloses a bidirectional DC-DC converter based on zero-voltage soft switching, which comprises a high-voltage-side full-bridge circuit, the high-voltage-side full-bridge circuit is composed of four high-voltage switching tubes S1 to S4, body diodes D1 to D4 corresponding to the switching tubes and junction capacitors C1 to C4, the output end of the high-voltage-side full-bridge circuit is connected with a high-voltage-side filter capacitor Ch in parallel, and the output end of the high-voltage-side filter capacitor Ch is connected with the output end of the high-voltage-side full-bridge circuit. The voltage stabilizing circuit is used for stabilizing the voltage Uh of the high-voltage side, and the low-voltage side full-bridge circuit is composed of four low-voltage switch tubes S5-S8, body diodes D5-D8 corresponding to the switch tubes and junction capacitors C5-C8. According to the bidirectional DC-DC converter based on the zero-voltage soft switching, zero-voltage switching-on and switching-off of the full-bridge switching tubes are achieved through the resonance network, switching loss is remarkably reduced, particularly, the efficiency is improved by 5%-8% compared with a traditional hard switching under the high-frequency working condition, the rapid dynamic response characteristic is achieved, and the reliability of the converter is improved through the combination of leakage inductance of the transformer and an external resonance inductor. And in combination with phase shift control, full-range soft switching from 20% of rated load to full load is realized.

The invention provides a current source resonance type inter-line direct current power flow controller topology and a frequency conversion control method. The current source resonance type inter-line direct current power flow controller topology comprises a first current source type H bridge, a second current source type H bridge, an isolation transformer and a resonance capacitor, each H bridge serves as a port and is composed of four bidirectional switches, and each bidirectional switch comprises two power MOSFETs with common source electrodes connected in series; the turn ratio of the primary side to the secondary side of the isolation transformer is 1: 1; the two resonant capacitors and the leakage inductor of the isolation transformer form a CLC resonant circuit; wherein the direct current side of the first current source type H bridge is connected with a first direct current line, and the alternating current side is connected with the primary side of the isolation transformer through the CLC resonance circuit; the direct-current side of the second current source type H bridge is connected with a second direct-current line, and the alternating-current side is connected with the secondary side of the isolation transformer through the CLC resonance circuit; during operation, the first current source type H bridge and the second current source type H bridge invert direct current of a direct current line into alternating current in a square wave form and inject the alternating current into the CLC resonance circuit.

This invention relates to a triple-multiplier auxiliary circuit for a series-type 12-pulse rectifier, belonging to the field of power electronics technology. It solves the problems of existing pulse multiplier circuits used in the DC side of series-type 12-pulse rectifiers, which suffer from large turns ratios in the primary and secondary windings of the auxiliary transformer, resulting in significant leakage inductance and poor harmonic suppression. Furthermore, the large turns ratio and the presence of numerous diodes in the multiplier circuit also contribute to its complex structure and increased manufacturing difficulty. This invention's triple-multiplier auxiliary circuit, by adjusting the turns ratio of the primary and secondary windings of each auxiliary transformer, allows the auxiliary diodes D... f1 and auxiliary diode D f2 The conduction times of the two diodes are 1 / 3 or 1 / 4 of their respective input voltage cycles, enabling the first diode rectifier bridge and / or the second diode rectifier bridge to operate simultaneously or alternately, thereby achieving a pulse multiplication of 3 times. This invention is mainly used to achieve pulse multiplication.

An impedance matching apparatus for providing impedance matching for an RF component. The apparatus includes a balun transformer circuit having a primary coil at an input side of the balun transformer circuit. The primary coil can be connected to a signal source to receive an input signal from the signal source. The balun transformer circuit further includes a secondary coil at an output side of the balun transformer circuit, the secondary coil being coupled to the primary coil to supply an output signal to the RF component and having a parasitic leakage inductance configured to match the output impedance of the signal source to the input impedance of the RF component