CN106685103B - Parameter setting method of L CC L resonance structure - Google Patents

Abstract

The invention discloses a parameter setting method of an L CC L resonant structure, which comprises a resonant inductor, an electromagnetic induction type wireless Power transmission (ICPT) system electric energy transmitting end coil, a parallel resonant capacitor and a series resonant capacitor, wherein the ICPT system electric energy transmitting end coil is connected with the series resonant capacitor in series, then is connected with the parallel resonant capacitor in parallel, and then is connected with the resonant inductor in series, and a method of compensating L CC L resonant structure input end higher harmonic current by adopting L CC L resonant structure input end fundamental current is adopted to give a parameter design relation of the structure and give different constraint conditions, so that the problem of nonlinear programming is established, the parameter setting is realized, and the purpose that an ICsystem PT full-bridge inverter connected with an L CC L resonant structure works in a zero current turn-off state is achieved.

Description

Parameter setting method of L CC L resonance structure

Technical Field

The invention relates to the technical field of wireless power transmission, in particular to a power transmitting end resonance structure of an electromagnetic induction type non-contact power transmission system.

Background

An electromagnetic induction type wireless Power Transfer (ICPT) system utilizes the principle of electromagnetic induction and adopts the mode of electromagnetic resonance to realize non-contact transmission of electric energy. Compared with the laser and microwave carrier mode, the technology has the advantages of no influence of middle nonmagnetic barriers and small influence on organisms, and is one of the best modes for transmitting high-power electric energy in a short distance of less than 10m in a non-contact manner. The ICPT technology provides a new feasible solution for solving the problems of mobile power supply of a maglev train, power supply of an embedded medical device in a closed space, monitoring electric energy transmission without an underwater cable, wireless charging of an electric automobile and the like.

The wireless power transmission technology based on the electromagnetic induction principle at present has a resonant network structure aiming at the coil leakage inductance, namely a magnetic coupling resonant structure, the prior art mainly adopts a first-order basic structure and a second-order L C structure, and a small number of three-order resonant network structures, in the aspect of the three-order resonant network, most of the ideas of soft switch resonant converters are used for reference, and the L C L resonant structure is mainly used.

L C L resonant network structure increases output power capability of ICPT system greatly by means of resonance, and utilizes frequency selection characteristic of the structure when resonant, current waveform of input coil presents quasi sine wave waveform, electromagnetic interference is reduced indirectly, besides, L C L resonant structure can solve circulation problem between coil parallel capacitance and high frequency inverter, therefore, L C L resonant network has better performance compared with other resonant networks so far, and is the mainstream technical direction in this field.

At present, in the design of adopting L C L three-order structure as resonance compensation structure, it is a symmetrical structure, i.e. two-port network input and output are completely symmetrical, and input two port and output two port can be interchanged, so that it is intended to ensure that input impedance and output impedance have no reactance component and all present pure resistance characteristics, and it is intended to attain the goal of inverter zero-voltage turn-on (ZVS) and zero-current turn-off (ZCS).

Disclosure of Invention

Aiming at the prior art, the technical problem to be solved by the invention is to overcome the defects in the prior art, and provide a parameter setting method of an L CC L resonant structure, which can realize zero current turn-off of an ICPT system inverter.

The invention discloses a parameter setting method of an L CC L resonance structure, which comprises the following steps:

step 1, determining L resonance frequency f adopted by CC L resonance structure₀＝Q_f0L CC L harmonic is obtained according to formula (1) and formula (2)Resonant angular frequency omega of vibration structure₀：

f₀＝Q_f0(1)

ω₀＝2πf₀(2)

Step 2: coupling coil resonance frequency f at the transmitting end₀Next, an ICPT power transmitting end coil inductance L 'was measured'₂L of inductance value₂Is Q_L2ICPT electric energy transmitting end coil alternating current resistor R'_lResistance value R of_lIs Q_RlAt this time R_l＝Q_RlMeasuring ICPT system electric energy receiving end reflection impedance Z'_fIs a reflection impedance value Z_f(coupling coil resonance frequency f at transmitting end₀Lower determination) of Z_fThe resistance portion is denoted as Q_Zf，Z_f＝Q_Zf；

Step 3, determining L CC L resonant structure component parameter relation by using a method of compensating high-order harmonic current by using fundamental current:

L₂＝Q_L2(3D)

R_l＝Q_Rl(3E)

Z_f＝Q_Zf(3F)

and 4, obtaining a relation that the voltage of the L CC L structural component meets the following relation according to the relation among the L CC L resonant structural component parameters in the step 3:

U_L1＝I_out(R_l+Z_f) (4C)

U_L2＝ω₀I_outL₂(4D)

and 5, obtaining a L CC L structural component current satisfying relation according to the relation among L CC L resonant structural component parameters in the step 3:

I_C2＝I_out(5B)

I_L2＝I_out(5D)

step 6, determining L CC L resonant structure rated output power P_out,nomThereby obtaining L CC L resonant structure output power P_outSatisfies the relationship:

P_out＝I_out ²(Z_f)≥P_out,nom(6)

and 7: determining capacitance C'₁Withstand voltage value U_C1Maximum value of U_C1maxCapacitor C'₂Withstand voltage value U_C2Maximum value of U_C2maxInductor L'₁Withstand voltage value U_L1Maximum value of U_L1maxInductor L'₂Withstand voltage value U_L2Maximum value of U_L2maxAnd obtaining the withstand voltage of the component which meets the condition:

0＜U_C1≤U_C1max(7A)

0＜U_C2≤U_C2max(7B)

0＜U_L1≤U_L1max(7C)

0＜U_L2≤U_L2max(7D)

and 8: determining capacitance C'₁Allowing a current value I to flow_C1Maximum value of (1)_C1maxCapacitor C'₂Allowing a current value I to flow_C2Maximum value of (1)_C2maxInductor L'₁Allowing a current value I to flow_L1Maximum value of (1)_L1maxInductor L'₂Allowing a current value I to flow_L2Maximum value of (1)_L2maxTherefore, the component allowed current value satisfies the condition:

0＜I_C1≤I_C1max(8A)

0＜I_C2≤I_C2max(8B)

0＜I_L1≤I_L1max(8C)

0＜I_L2≤I_L2max(8D)

and step 9: determining capacitance C'₁The capacitance C is obtained under practical conditions₁Minimum parameter value C of_1minDetermining capacitance C'₁The capacitance C is obtained under practical conditions₁Maximum parameter value C of_1max；

Determining capacitance C'₂The capacitance C is obtained under practical conditions₂Minimum parameter value C of_2minDetermining capacitance C'₂The capacitance C is obtained under practical conditions₂Maximum parameter value C of_2max；

Determining inductor L'₁Obtaining an inductance value L under practical conditions₁Minimum parameter value L_1minDetermining an inductance L'₁Obtaining an inductance value L under practical conditions₁Maximum parameter value of

Therefore, the actual values of the component parameters of the L CC L resonance structure meet the conditions that:

C_1min≤C₁≤C_1max(9A)

C_2min≤C₂≤C_2max(9B)

step 10:determining U_C1Weight coefficient k₁，U_C2Weight coefficient k₂，U_L1Weight coefficient k₃，U_L2Weight coefficient k₄，I_C1Weight coefficient k₅，I_C2Weight coefficient k₆，I_L1Weight coefficient k₇，I_L2Weight coefficient k₈Thus, the target function expression for achieving the optimum parameter value of the L CC L resonance structure is obtained:

Z＝k₁U_C1 ²+k₂U_C2 ²+k₃U_L1 ²+k₄U_L2 ²+k₅I_C1 ²+k₆I_C2 ²+k₇I_L1 ²+k₈I_L2 ²(10)

step 11: building a non-linear programming problem with V_in、I_outFor decision variables, the minimum objective function is an optimization objective, and the equality relation and inequality relation obtained in the steps 1, 3 to 10 are constraint conditions;

step 12, solving the nonlinear programming problem in the step 12 to obtain parameters L meeting L CC L resonance structure₁、C₁、C₂And V_inA value of (d);

step 13, calculating an equivalent direct current voltage value V of L CC L resonance structure parameters corresponding to the ICPT system inverter side_dc：

Further, when the bandwidth of the actual connecting wire is lower than 100 times of the fundamental frequency, the relation between the parameters of the L CC L resonant structure components in the step 3 is as follows:

the L CC L structure in the invention comprises a resonance inductor, an ICPT system electric energy transmitting end coil, a parallel resonance capacitor and a series resonance capacitor,an ICPT system electric energy transmitting end coil is connected in series with a series resonance capacitor, then connected in parallel with a parallel resonance capacitor and then connected in series with a resonance inductor, and an equivalent circuit corresponding to the structure is inductor L'₂And capacitor C'₂And ICPT system electric energy transmitting end coil alternating current resistor R'_lAnd reflection impedance Z 'of electric energy receiving end of ICPT system'_fAfter forming a serial branch, the capacitor C 'is connected with'₁Form a parallel branch circuit and finally carry out L'₁Form a series branch, respectively R_lIs R'_lResistance value of, Z_fIs Z'_fReflection resistance value of C₁Represents capacitance C'₁Capacitance value of (C)₂Represents capacitance C'₂Capacitance value of (L)₁Represents an inductance L'₁Value of inductance of L₂Represents an inductance L'₂Particularly illustrating the inductance L 'in the circuit'₂And capacitor C'₂And ICPT system electric energy transmitting end coil alternating current resistor R'_lAnd reflection impedance Z 'of electric energy receiving end of ICPT system'_fAnd capacitor C'₁And inductor L'₁All components are L CC L structure components, and satisfy:

resonance inductance and series resonance capacitance at angular frequency omega₀Form resonance, i.e.

Z_fDecomposable into a reactive component X_fAnd a resistance component R_fThe power receiving end of ICPT system is impedance-converted to eliminate its reactance component X_fRetaining only its resistance component R_f；

C₂Has a value of greater than

And is less than

In an ICPT system application, there is generally only one capacitor, which is called L C L resonant structure because of L₂The inductor of the electric energy transmitting end coil of the ICPT system usually presents larger inductive reactance, and high-frequency alternating current is directly injected into an L C L resonant structure, so that the amplitude of the current value injected into a L C L resonant structure is too small, and the electric energy transmitting end coil of the ICPT system connected behind the L C L resonant structure cannot be effectively driven to generate a stronger high-frequency alternating magnetic field.

The meaning of the parameter, P, in the L CC L resonant structure is first defined_out,nomRated output power, f, for output L CC L resonant structure₀Is L CC L structure resonance frequency, V_inAn input voltage effective value, R, of L CC L structure_fIs a resistance component, X, of the reflected impedance of the power receiving end of the ICPT system_fThe reactance component of the impedance is reflected by the power receiving end of the ICPT system. Coupling coil resonance frequency f at the transmitting end₀Measuring the reflection impedance Z of the power receiving end of the ICPT system_fTransmitting coil inductor L₂And is combined with Z_fThe resistance component is denoted as R_fThe reactance component being denoted X_f。

Input fundamental current value expression (11) of L CC L resonant structure at the moment of ICPT system inverter switching:

wherein the content of the first and second substances,

in the formula V_dcFor the output voltage amplitude, I, of the inverter of the ICPT system_in,1Input fundamental current value expression for L CC L resonant structure, I_in,off,1Input fundamental current value expression, C, of resonant structure of inverter switching time L CC L of ICPT system₂、I_in,1Is an unknown quantity.

If the dead zone interruption of the inverter is ignored, the square wave voltage value output by the inverter can be expanded into a Fourier series form shown in an equation (8), wherein when t is 0, the square wave voltage value corresponds to the switching time of the inverter of the ICPT system.

Since the L CC L type resonant network circuit structure has good low-pass filtering characteristic, if only V is considered_inFundamental wave, neglecting higher harmonics, obtaining V_inApproximate values of (a):

according to the circuit structure of L CC L, the relation shown in (15A) (15B) is as follows:

when L₁And C₁When the formula (16) is satisfied, the coil injection current value I_outTwo-port input voltage V of resonant network only with L CC L_inRelated to the reflected impedance Z_fIs irrelevant.

At this point L₁And C₁At an angular frequency of fundamental angular frequency omega₀Resonance is formed. Thus, equation (17) holds.

I_out＝-jω₀C₁V_in(17)

When only the fundamental wave is considered, the input current value of the L CC L resonant network is

Equation (18) is L CC L resonant network two-port input current, I_inNeutral-divided fundamental current I_in,1In addition, it also contains a large amount of higher harmonic current I_in,n(n-3, 5,7, …). I can be transformed by Fourier decomposition_inIs unfolded into the form of the formula (19),

when t is 0, it corresponds to the switching time of the inverter of the ICPT system. The sum of harmonic waves of the output current of the inverter at the switching moment is

When the electric energy receiving end is in a capacitance series compensation mode, the reflection resistance and the reflection reactance are increased along with the harmonic frequency, and the trends of the formulas (21) and (22) are presented. Wherein R is_f,n,serThe reflection resistance value X reflected to the electric energy transmitting end when the electric energy receiving end of the ICPT system adopts a capacitance series compensation mode_f,n,serThe reflected reactance value R reflected to the electric energy transmitting end when the electric energy receiving end of the ICPT system adopts a capacitance series compensation mode_load,0The value is the load resistance of the electric energy receiving end, n is the harmonic order, Q is the quality factor of the resonance circuit of the electric energy receiving end, and oc represents the direct proportion relation.

X_f,n,ser∝n (22)

When the compensation form of the electric energy receiving end is that the capacitors are connected in parallel, the reflection resistance is 0, and the reflection reactance increases along with the harmonic frequency, as shown in formulas (23) and (24). Wherein R is_f,n,parThe reflection resistance value X reflected to the electric energy transmitting end when the electric energy receiving end of the ICPT system adopts a capacitance parallel compensation mode_f,n,parThe reactance value of the reflected power is the value of the reflected reactance reflected to the power transmitting end when the power receiving end of the ICPT system adopts a capacitance parallel compensation mode, n is the harmonic order,and oc represents a proportional relationship.

X_f,n,par∝n (24)

It can be known that, when the harmonic frequency is higher, the reactance of the input end of the coupling coil increases with the increase of the harmonic frequency, and the C is connected with the branch of the coupling coil in parallel₁The reactance of the capacitor branch is rapidly smaller. Therefore, when the harmonic current is calculated, the current at the input port of the coupler can be ignored, the current branch of the coupler can be simplified, and when the angular frequency omega is n omega₀At time, L CC L resonant structure input impedance is

Order to

Equation (25) can be simplified to

Therefore, the equation (11) holds for the input harmonic current instantaneous value I of the L CC L resonant structure_in,off,nRepresented by formula (27):

thereby having

And because of

Therefore, the first and second electrodes are formed on the substrate,

as the fundamental frequency is mostly above 20kHz, the frequency of higher harmonic wave is above 2MHz after over 100 harmonics in an actual line, and the frequency is limited by the high-resistance characteristic of L CC L resonant network and the bandwidth of cables for connecting L CC L elements, and the 101 th harmonic wave is I_in,off,highThe influence of (2) is only 0.001%, and the 101 th harmonic component and above is to I_in,off,highThe influence of (c) is already small and negligible. Therefore, the computer program can be adopted to calculate the current value I of all higher harmonics under the harmonic wave of less than 100_in,off,highApproximated (free of fundamental component) as in equation (29):

switching time fundamental wave current I of inverter_in,off,1And higher harmonic current I_in,off,highAdding to obtain the instantaneous value I of the total current passing through the L CC L resonant structure at the moment of switching of the inverter_in(t ═ 0), calculated according to equation (26):

it is clear that the formula (31) holds,

namely, it is

In practical circumstances, limited by the wire bandwidth, only the fundamental wave and the following harmonics of order 100 are generally considered, and in order to make the inverter in the zero-current off state, it is necessary to ensure that the output current is in phase with the output voltage at the moment of switching the inverter, and equation (33) should be satisfied:

because the power factor correction technology is generally adopted by the electric energy receiving end in the ICPT system, the electric energy receiving end meets X_fIs equal to 0, thus C₂Satisfies the following conditions:

therefore, from the formula (32), correspondingly C₂Satisfy the range of

Further, the operating characteristics of the L CC L resonant structure were analyzed, and the fundamental wave angular frequency ω can be found by the analysis formula (18)₀At the bottom, L CC L resonant network inputs fundamental current I_in,1Comprising a fundamental active current component I_in,1,aAnd a fundamental reactive current component I_in,1,rCan be described as formula (35-37)

I_in,1＝I_in,1,a+I_in,1,r(35)

I_in,1,a＝V_inω₀ ²C₁ ²(R_l+Z_f) (36)

When the L CC L resonant network of the invention is adopted, the frequency of the fundamental wave angular frequency omega is₀The fundamental reactive current of the lower input L C L resonant network is

Wherein C is_2,symAdopts a symmetrical L C L resonant network C₂Capacitance value of C_2,asymL CC L type resonant network C proposed by the invention₂Capacitance value, inThe symmetric L C L resonant network parameters and the L CC L resonant network parameters provided by the invention are distinguished by a mark, wherein a subscript sym corresponds to symmetric (symmetry) L C L resonant network parameters, and a subscript asym corresponds to L CC L resonant network parameters provided by the invention.

At this time, the phase of the fundamental reactive current leads L CC L resonant network input port voltage phase pi/2, and the fundamental angular frequency omega₀The method for compensating the phase of the high-order current harmonic wave lagging input voltage by utilizing the leading input voltage phase of the reactive current of the fundamental wave forms a zero current state or an approximate zero current state at the moment of turning off the inverter, thereby greatly reducing the switching loss of the inverter, improving the efficiency of an ICPT system at the electric energy transmitting end.

However, when the L CC L resonant structure is adopted, part of fundamental wave reactive current is introduced, so that the apparent power is increased to a certain extent, and the specific expression is that when the L CC L resonant structure is adopted, the effective value of the on-state current of the inverter is slightly larger than that when the symmetrical L C L structure is adopted.

The real and reactive power of the fundamental wave input to the L CC L resonant structure can be represented by equations (39-41),

Q_1,sym＝0 (41)

P_1.symactive power, P, output for a symmetrical L C L resonant structure_1.asymL CC L harmonic with the parameter relationship of the inventionActive power, Q, of the vibrating structure output_1.symReactive power, Q, output for a symmetrical L C L resonant structure_1.asymReactive power, V, output for L CC L resonant structure with parameter relationship of the invention_in,1The effective value of the fundamental voltage of the output voltage of the inverter of the ICPT system.

As can be seen from the simplified model of the L CC L resonant network under the higher harmonics in fig. 3, the higher harmonics do not provide active power to the coupling coil in the L CC L resonant structure of the present invention, only the fundamental wave provides active power to the coupling coil, and the higher harmonics provide only reactive power, which can be obtained from equation (26), and the reactive power of the higher harmonics under both structures is,

in the formula Q_n.symReactive power, Q, output for n-th harmonic of symmetrical L C L resonant structure_n.symReactive power, V, output for the n-th harmonic of the L CC L resonant structure of the invention_in,nThe harmonic voltage effective value is the nth harmonic voltage effective value of the output voltage of the ICPT system inverter, and n is the harmonic frequency.

Total high order harmonic reactive power of

Generally, only harmonics below 100 are calculated due to the bandwidth limitation of the actual connecting wire, and the result of formula (43) can be calculated by computer programming as shown in formula (44)

The symmetrical L C L resonant structure network and the L CC L resonant structure network of the invention input apparent power, namely the inverter outputs apparent power when the symmetrical L C L resonant structure network and the L CC L resonant structure network of the invention are adopted,

in the formula S_symFor inverter output apparent power, S, when adopting symmetrical L C L resonant structure_asymThe inverter outputs apparent power for the L CC L resonant structure with the parameter relationships of the present invention.

From the formulas (45), (46), the apparent power and the coupler internal resistance R_lElectric energy receiving end reflection resistor R_fL at fundamental frequency₁Reactance value Z₁It is related. Since the input voltages of the two different types of resonant networks are the same, the ratio of the effective value of the inverter output current when the two different types of resonant networks are adopted can be calculated by the formulas (45) and (46)

In practical application, because typical working frequencies of an ICPT system are all above 20kHz, the on-state loss of an ICPT system inverter increased by adopting a L CC L structure with the parameter relationship is far less than the switching loss of the ICPT system inverter reduced by adopting a L CC L structure with the parameter relationship, therefore, in practical application, the L CC L structure with the parameter relationship can reduce the loss of an electric energy transmitting end of the ICPT system to a greater extent and improve the efficiency of the electric energy transmitting end of the ICPT system, in addition, the L CC L resonance structure with the parameter relationship realizes zero current turn-off of an ICPT system inverter power tube, reduces the switching stress of the power tube and can reduce the electromagnetic interference generated by the ICPT system inverter to a greater extent.

Due to the adoption of the technical scheme, the invention has the following advantages:

(1) by adopting the L CC L resonance structure parameter setting method provided by the invention, the instantaneous value of the current passing through the power tube at the turn-off time is zero, the zero current turn-off of the power tube is realized, and the switching loss and the switching stress of the power tube are reduced.

(2) L CC L resonant structure output current effective value (namely line)Effective value of loop injection current) I_outIs I_out＝-jω₀C₁V_inAnd a resistance component R in the reflected impedance_fAnd the decoupling design of the electric energy transmitting end and the electric energy receiving end of the ICPT system is realized.

Drawings

Fig. 1 is a schematic diagram of L CC L resonant structure proposed by the present invention.

Fig. 2 is an equivalent circuit diagram of L CC L resonant structure proposed by the present invention.

Fig. 3 is a schematic diagram of a simplified model of the L CC L resonant network at higher harmonics.

FIG. 4 is a graph showing the relationship between the output voltage, current and driving signal of the ICPT system inverter of L CC L resonant structure when the parameter design method of the present invention is adopted.

FIG. 5 is a waveform of the input current of the L CC L resonant structure proposed by the present invention at near full load condition.

FIG. 6 is a waveform diagram of the input current of the L CC L resonant structure under the condition of near no-load.

Fig. 7 is a graph showing the variation trend of the ratio of the effective values of the inverter output currents of the ICPT system.

Fig. 8 is a graph comparing the single IGBT loss tendency of an ICPT system inverter using a conventional L C L resonant structure and the L CC L resonant structure of the present invention.

Fig. 9 is a flowchart of a parameter setting method of the L CC L resonant structure proposed by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings. The specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting.

The invention provides an L CC L type resonance structure for an ICPT system, which is shown in figure 1 and comprises a resonance inductor 110, an ICPT system electric energy transmitting end coil 111, a parallel resonance capacitor 211 and a series resonance capacitor 210, wherein after the ICPT system electric energy transmitting end coil 111 is connected with the series resonance capacitor 210 in series and then connected with the parallel resonance capacitor 211 in parallel,the equivalent circuit is shown in FIG. 2, and the equivalent circuit corresponding to the structure is inductor L'₂And capacitor C'₂And ICPT system electric energy transmitting end coil alternating current resistor R'_lAnd reflection impedance Z 'of electric energy receiving end of ICPT system'_fAfter forming a serial branch, the capacitor C 'is connected with'₁Form a parallel branch circuit and finally carry out L'₁Form a series branch, respectively R_lIs R'_lResistance value of, Z_fIs Z'_fReflection resistance value of C₁Represents capacitance C'₁Capacitance value of (C)₂Represents capacitance C'₂Capacitance value of (L)₁Represents an inductance L'₁Value of inductance of L₂Represents an inductance L'₂The inductance value of (c). Q₁、Q₂、Q₃、Q₄To switch tubes, D₁、D₂、D₃、D₄The switching Transistor of the ICPT system of the embodiment is selected as an Insulated Gate Bipolar Transistor (IGBT) for the diode. D₁、D₂、D₃、D₄In order to correspond to the anti-parallel diode of the IGBT, the present embodiment employs a fast recovery diode. Capacitor C₁、C₂Metallized polypropylene capacitors are used. . V_inEffective value of input voltage of L CC L resonant structure, the embodiment V_inThe voltage was 129V.

FIG. 3 is a schematic diagram of a simplified model of the L CC L resonant network at higher harmonics, when the harmonic order is higher, the reactance at the input of the coupling coil increases with the harmonic order, and the C is connected in parallel with the branch of the coupling coil₁The reactance of the capacitor branch is rapidly smaller, so that the current at the input port of the coupler can be ignored when the calculation of the high-order harmonic current is carried out, and the current branch of the coupler is simplified, as shown by the dotted line part in fig. 3, and the solid line part in fig. 3 forms a simplified model of L CC L resonant network.

FIG. 5 is a waveform diagram of the input current of L CC L type resonant structure of ICPT system according to the present invention when the parameters of the present embodiment are adopted, the signal bandwidth of the voltage probe is 200MHz, the signal bandwidth of the current probe is 100MHz, and the signal bandwidth is for clearer observationThe voltage and current peak condition of the sample machine is inspected, and the noise filter of the oscilloscope is closed. In fig. 4, from top to bottom, the 1-channel signal is the voltage waveform of the driving signal of the single IGBT of the inverter, and the 2-channel signal is the voltage V between the collector and the emitter of the single IGBT of the inverter_ceThe waveform of the 4-channel resonant network input current is L CC L.

FIG. 6 is a waveform diagram of an input current of L CC L type resonant structure of an ICPT system according to the present invention when the reflected impedance of the power receiving end of the ICPT system is decreased and the power emitting end of the ICPT system is close to no-load by using the parameters of the present embodiment, wherein in FIG. 5, from top to bottom, a 1-channel signal is a voltage waveform of a driving signal of a single IGBT of an inverter, and a 2-channel signal is a voltage V between a collector and an emitter of the single IGBT of the inverter_ceThe waveform of the 4-channel resonant network input current is L CC L.

As can be seen from fig. 5 and 6, the L CC L resonant structure provided by the invention can realize zero current turn-off of the inverter power tube of the ICPT system, reduce the switching loss and switching stress of the switching tube, and improve the overall efficiency of the ICPT system.

FIG. 7 shows (R)_l+R_f)/Z₁To I_asym(rms)/I_sym(rms) influence simulation chart, and when (R) is observed in FIG. 7_l+R_f)/Z₁When equal to 0, I_asym(rms)/I_sym(rms) is a maximum, approximately 3.3 times, which corresponds to ignoring the internal coupler resistance R_lAnd no reflective impedance (zero load at the power receiving end). Due to Z₁Is L CC L resonant network parameter, which is a fixed value R_lFor the coupler internal resistance parameter, this parameter is also a fixed value. Only R_fIn order to reflect impedance, ICPT systems vary with the operating conditions of the load when operating. As can be seen in FIG. 7, with R_fIncrease, (R)_l+R_f)/Z₁The ratio of (A) is increased, the ratio of the effective value of the output current of the inverter is reduced and rapidly approaches 1 when (R) is increased_l+R_f)/Z₁When the ratio of (A) to (B) is 2, I_asym(rms)/I_symThe (rms) ratio is 1.004, namely the effective value of the output current of the inverter is higher than that of the output current of the inverter when the L CC L structure of the invention is adoptedThe current effective value is increased by only 0.4% in the conventional L C L structure, so that the on-state loss of the switching tube is almost negligible.

Fig. 8 is a comparison graph of the loss trend of a single IGBT of an ICPT system inverter under a conventional L C L resonant structure and an ICPT system inverter under an ICPT system resonant structure employing L CC L resonant structure having the parameter relationship of the present invention, wherein a curved surface 1 represents a trend of the loss trend of a single IGBT of an inverter under a conventional L C L resonant structure network, and a curved surface 2 represents a trend of the loss trend of a single IGBT of an inverter under a L CC L resonant structure having the parameter relationship of the present invention, fig. 7 shows that the loss trend of the single IGBT of the inverter is gradually increased as the output current amplitude of the resonant structure is increased and the switching frequency of the inverter is increased when two different resonant structures are employed, but when a conventional L C L resonant structure is employed, the loss power of the IGBT is increased rapidly as the switching frequency is increased, when the switching frequency is 500Hz or more, the loss power of the single IGBT of the inverter is significantly higher than the loss power pt of the IGBT under the conventional L C L C resonant structure when the conventional L CC L resonant structure is employed, and when the switching frequency is higher than the typical operating frequency of the ICPT system is above 500 kHz, so that the total ICPT of the present invention can effectively increase the loss efficiency.

Further, according to the flowchart shown in fig. 9, the specific implementation steps of the parameter setting method of the present invention are illustrated:

step 1, firstly determining L CC L resonance frequency f adopted by resonance structure₀＝Q_f040000Hz, the resonance angular frequency equation constraint of L CC L resonance structure is obtained:

f₀＝Q_f0＝40000Hz

ω₀＝2πf₀＝2×π×40000rad/s

step 2: coupling coil resonance frequency f at the transmitting end₀Measuring coil inductance L at 40000Hz of ICPT power transmitting terminal₂Has a value of Q_L2105.6965 mu H, ICPT electric energy transmitting end coil alternating current internal resistance R_lHas a value of Q_RlMeasuring the reflection impedance Z of the power receiving end of the ICPT system under the condition of 0.05 omega _f2 Ω (resonance frequency f of coupling coil at transmitting end)₀Lower determination) of Z_fThe resistance portion is denoted as Q_Zf＝2Ω。

And 3, obtaining a constraint condition of a parameter equation of the L CC L resonant structure component from the parameter relation of the L CC L resonant structure component:

L₂＝Q_L2

R_l＝Q_Rl

Z_f＝Q_Zf

step 4, obtaining constraint conditions of a L CC L structural element voltage equation according to the parameter relation of the L CC L resonance structural element component:

U_L1＝I_out(R_l+Z_f)

U_L2＝ω₀I_outL₂

step 5, obtaining current equality constraint conditions of the L CC L structural component according to the parameter relation of the L CC L resonant structural component provided by the invention:

I_C2＝I_out

I_L2＝I_out

step 6, determining L CC L resonant structure rated output power P_out,nom1000W, the L CC L resonant structure output power inequality constraint is obtained:

P_out＝I_out ²(Z_f)≥1000W

and 7: determining capacitance C'₁Withstand voltage value U_C1Maximum value of U_C1max2500V, capacitance C'₂Withstand voltage value U_C2Maximum value of U_C2max2500V, inductor L'₁Withstand voltage value U_L1Maximum value of U_L1max2000V, inductor L'₂Withstand voltage value U_L2Maximum value of U_L2maxObtaining a withstand voltage inequality constraint condition of the component as 1000V:

0＜U_C1≤2500V

0＜U_C2≤2500V

0＜U_L1≤2000V

0＜U_L2≤1000V

and 8: determining capacitance C'₁Allowing a current value I to flow_C1Maximum value of (1)_C1max40A, capacitance C'₂Allowing a current value I to flow_C2Maximum value of (1)_C2max40A, inductor L'₁Allowing a current value I to flow_L1Maximum value of (1)_L1max40A, inductor L'₂Allowing a current value I to flow_L2maxObtaining a component permission constraint condition through a current value inequality:

0＜I_C1≤40A

0＜I_C2≤40A

0＜I_L1≤40A

0＜I_L2≤40A

and step 9: determining capacitance C'₁The capacitance C is obtained under practical conditions₁Minimum parameter value C of_1minCapacitance C 'was determined at 0.01. mu.F'₁The capacitance C is obtained under practical conditions₁Maximum parameter value C of_1max＝1.32μF。

Determining capacitance C'₂The capacitance C is obtained under practical conditions₂Minimum parameter value C of_2minCapacitance C 'was determined at 0.01. mu.F'₂The capacitance C is obtained under practical conditions₂Maximum parameter value C of_2max＝1.32μF。

Determining inductor L'₁Obtaining an inductance value L under practical conditions₁Minimum parameter value L _1min0 muH, determining an inductance of L'₁Obtaining an inductance value L under practical conditions₁Maximum parameter value of (2):

obtaining the constraint condition of an actual available value inequality of the component parameters of the L CC L resonance structure:

0.01μF≤C₁≤1.32μF

0.01μF≤C₂≤1.32μF

0μH≤L₁≤84.5572μH

step 10: determining U_C1Weight coefficient k₁Determining U as 1_C2Weight coefficient k₂Determining U as 1_L1Weight coefficient k₃Determining U as 1_L2 Weight coefficient k ₄1, determining I_C1Weight coefficient k₅625, determine I_C2Weight coefficient k₆625, determine I_L1Weight coefficient k₇625, determine I_L2Weight coefficient k₈625, the target function expression for achieving the optimum parameter values for the L CC L resonant structure is obtained:

Z＝U_C1 ²+U_C2 ²+U_L1 ²+U_L2 ²+625×(I_C1 ²+I_C2 ²+I_L1 ²+I_L2 ²)

step 11: with V_in、I_outFor decision variables, the objective function is at a minimumOptimizing the target, wherein the equality relation and the inequality relation obtained in the steps 1, 3 to 10 are constraint conditions, and establishing a nonlinear programming problem:

min Z＝U_C1 ²+U_C2 ²+U_L1 ²+U_L2 ²+625×(I_C1 ²+I_C2 ²+I_L1 ²+I_L2 ²)

satisfy the requirement of

(a) L CC L element relationship constraint

L₂＝Q_L2

R_l＝Q_Rl

Z_f＝Q_Zf

(b) Constraint of resonance frequency

f₀＝Q_f0＝40000Hz

ω₀＝2πf₀＝2×π×40000rad/s

(c) L CC L structural element voltage relationship

U_L1＝I_out(R_l+Z_f)

U_L2＝ω₀I_outL₂

(d) L CC L structural element current relationship

I_C2＝I_out

I_L2＝I_out

(e) L CC L structural output power constraint

P_out＝I_out ²(Z_f)≥1000W

(f) Component withstand voltage value constraint

0＜U_C1≤2500V

0＜U_C2≤2500V

0＜U_L1≤2000V

0＜U_L2≤1000V

(g) Maximum allowable component overcurrent value constraint

0＜I_C1≤40A

0＜I_C2≤40A

0＜I_L1≤40A

0＜I_L2≤40A

(h) Constraint of actual available value of component parameter

0.01μF≤C₁≤1.32μF

0.01μF≤C₂≤1.32μF

0μH≤L₁≤84.5572μH

Step 12, solving the nonlinear programming problem to obtain the optimum parameter value L of the L CC L resonance structure meeting the actual use requirement₁、C₁、C₂And V_inThe value of (c). The results are as follows:

C₁≈0.2892μF

C₂≈0.4218μF

L₁≈54.75μH

V_in≈307.69V

step 13, calculating an equivalent direct current voltage value V of L CC L resonance structure parameters corresponding to the ICPT system inverter side_dc。

Fig. 4 shows the corresponding relationship between the output voltage, the current and the inverter driving signal of the ICPT system of the L CC L resonant structure when the parameter design method of the present invention is adopted, and fig. 4 shows, from top to bottom, the input voltage waveform of the L CC L resonant structure, the input current waveform of the L CC L resonant structure, the inverter single IGBT driving signal 1 and the inverter single IGBT driving signal 2.

As can be seen from fig. 4, as seen from the instantaneous value of the output current of the inverter at the switching time corresponding to the dotted line in the figure, at the moment of switching off the IGBT of the inverter, the current value of the IGBT is reduced to 0, and the IGBT enters the freewheeling state of the anti-parallel diode, so that the zero-current switching off of the switching tube of the inverter is realized.

The above are examples of the present invention, and are intended to be illustrative and not limiting. Other variations may be made on the above description and it is not necessary, nor exhaustive, to claim all embodiments. All changes made according to the technical scheme of the invention belong to the protection scope of the invention when the adopted structure and the parameter design method thereof do not exceed the scope of the technical scheme of the invention.

Claims (2)

1. An L CC L resonance structure parameter setting method includes a resonance inductor (110), an ICPT system electric energy transmitting end coil (111), a parallel resonance capacitor (211) and a series resonance capacitor (210), wherein the ICPT system electric energy transmitting end coil (111) is connected with the series resonance capacitor (210) in series, then connected with the parallel resonance capacitor (211) in parallel, and finally connected with the resonance inductor (110) in series, and an equivalent circuit corresponding to the structure is inductor L'₂And capacitor C'₂And ICPT system electric energy transmitting end coil alternating current resistor R'_lICPT system powerReceiving end reflective impedance Z'_fAfter forming a serial branch, the capacitor C 'is connected with'₁Form a parallel branch circuit and finally carry out L'₁Form a series branch, respectively R_lIs R'_lResistance value of, Z_fIs Z'_fReflection resistance value of C₁Represents capacitance C'₁Capacitance value of (C)₂Represents capacitance C'₂Capacitance value of (L)₁Represents an inductance L'₁Value of inductance of L₂Represents an inductance L'₂The inductance value of (a), wherein the parameter setting method comprises:

step 1, determining L resonance frequency f adopted by CC L resonance structure₀＝Q_f0Obtaining L CC L resonance angular frequency omega according to formula (1) and formula (2)₀：

f₀＝Q_f0(1)

ω₀＝2πf₀(2)

Step 2: coupling coil resonance frequency f at the transmitting end₀Next, an ICPT power transmitting end coil inductance L 'was measured'₂L of inductance value₂Is Q_L2ICPT electric energy transmitting end coil alternating current resistor R'_lResistance value R of_lIs Q_RlMeasuring ICPT system electric energy receiving end reflection impedance Z'_fIs a reflection impedance value Z_fIs a reaction of Z_fThe resistance portion is denoted as Q_Zf；

Step 3, determining L CC L resonant structure component parameter relation by using a method of compensating high-order harmonic current by using fundamental current:

L₂＝Q_L2(3D)

R_l＝Q_Rl(3E)

Z_f＝Q_Zf(3F)

and 4, obtaining a relation that the voltage of the L CC L structural component meets the following relation according to the relation among the L CC L resonant structural component parameters in the step 3:

U_L1＝I_out(R_l+Z_f) (4C)

U_L2＝ω₀I_outL₂(4D)

and 5, obtaining a L CC L structural component current satisfying relation according to the relation among L CC L resonant structural component parameters in the step 3:

I_C2＝I_out(5B)

I_L2＝I_out(5D)

step 6, determining L CC L resonant structure rated output power P_out,nomThereby obtaining L CC L resonant structure output power P_outSatisfies the relationship:

P_out＝I_out ²(Z_f)≥P_out,nom(6)

and 7: determining capacitance C'₁Withstand voltage value U_C1Maximum value of U_C1maxCapacitor C'₂Withstand voltage value U_C2Maximum value of U_C2maxInductor L'₁Withstand voltage value U_L1Maximum value of U_L1maxInductor L'₂Withstand voltage value U_L2Maximum value of U_L2maxAnd obtaining the withstand voltage of the component which meets the condition:

0＜U_C1≤U_C1max(7A)

0＜U_C2≤U_C2max(7B)

0＜U_L1≤U_L1max(7C)

0＜U_L2≤U_L2max(7D)

and 8: determining capacitance C'₁Allowing a current value I to flow_C1Maximum value of (1)_C1maxCapacitor C'₂Allowing a current value I to flow_C2Maximum value of (1)_C2maxInductor L'₁Allowing a current value I to flow_L1Maximum value of (1)_L1maxInductor L'₂Allowing a current value I to flow_L2Maximum value of (1)_L2maxTherefore, the component allowed current value satisfies the condition:

0＜I_C1≤I_C1max(8A)

0＜I_C2≤I_C2max(8B)

0＜I_L1≤I_L1max(8C)

0＜I_L2≤I_L2max(8D)

and step 9: determining capacitance C'₁The capacitance C is obtained under practical conditions₁Minimum parameter value C of_1minDetermining capacitance C'₁The capacitance C is obtained under practical conditions₁Maximum parameter value C of_1max；

Determining capacitance C'₂The capacitance C is obtained under practical conditions₂Minimum parameter value C of_2minDetermining capacitance C'₂The capacitance C is obtained under practical conditions₂Maximum parameter value C of_2max；

Determining inductor L'₁Obtaining an inductance value L under practical conditions₁Minimum parameter value L_1minDetermining an inductance L'₁Obtaining an inductance value L under practical conditions₁Maximum parameter value of

Therefore, the actual values of the component parameters of the L CC L resonance structure meet the conditions that:

C_1min≤C₁≤C_1max(9A)

C_2min≤C₂≤C_2max(9B)

step 10: determining U_C1Weight coefficient k₁，U_C2Weight coefficient k₂，U_L1Weight coefficient k₃，U_L2Weight coefficient k₄，I_C1Weight coefficient k₅，I_C2Weight coefficient k₆，I_L1Weight coefficient k₇，I_L2Weight coefficient k₈Thus, the target function expression for achieving the optimum parameter value of the L CC L resonance structure is obtained:

Z＝k₁U_C1 ²+k₂U_C2 ²+k₃U_L1 ²+k₄U_L2 ²+k₅I_C1 ²+k₆I_C2 ²+k₇I_L1 ²+k₈I_L2 ²(10)

step 11: building a non-linear programming problem with V_in、I_outFor decision variables, the minimum objective function is an optimization objective, and the equality relation and inequality relation obtained in the steps 1, 3 to 10 are constraint conditions;

step 12, solving the nonlinear programming problem in the step 11 to obtain parameters L meeting L CC L resonance structure₁、C₁、C₂And V_inA value of (d);

step 13, calculating an equivalent direct current voltage value V of L CC L resonance structure parameters corresponding to the ICPT system inverter side_dc：

2. The method for setting parameters of the L CC L resonance structure as claimed in claim 1, wherein the relationship among parameters of L CC L resonance structure components in the step 3 is as follows:

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