Power analysis method and system for l-llc resonant converter

Abstract

The application provides a power analysis method and system of an L-LLC resonant converter, the method comprising: obtaining a relationship between a normalized operating frequency and a normalized output power of each operating mode according to a boundary condition of the operating mode and an expression of the normalized output power; obtaining a range of the normalized output power of each operating mode according to a range of the normalized operating frequency of each operating mode and the relationship; substituting the range of the normalized operating frequency and the range of the normalized output power of each operating mode into the boundary condition of each operating mode and the expression of the normalized output power to solve a range of gain; and obtaining a range of original output power of each operating mode according to the range of the normalized output power and the range of gain. The application can accurately obtain the power output capability of the converter under different gains while ensuring good soft switching characteristics of the converter.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronic transformers, and particularly relates to a power analysis method and system of an L-LLC resonant converter. BACKGROUND

[0002] Power electronic transformer (PET) is an electronic power system that replaces the traditional transformer through high-frequency energy conversion technology. The power electronic transformer used for energy transmission and electrical isolation between two DC buses is called DC power electronic transformer (DCPET). DCPET is widely used in flexible DC transmission and distribution networks, new energy grid connection, and energy internet, and all other fields that may use medium and high voltage bidirectional isolation DC conversion. The L-LLC resonant converter is increasingly widely used in flexible power transmission due to its advantages of zero-voltage turn-on and bidirectional high gain, but the demand for its wider range of output voltage regulation is increasing.

[0003] In order to further broaden the output voltage gain range, a super-wide gain range regulation method of an L-LLC resonant converter is currently used to control the existing L-LLC topology through corresponding switching tubes, thereby performing topology conversion control. When working in a higher gain range, a full-bridge mode is used; when working in a lower gain range, a half-bridge mode is used, and the input voltage utilization rate is halved to achieve a wider gain range.

[0004] However, under the topology conversion control strategy of the L-LLC resonant converter, due to multiple resonant components and different operating modes, the maximum output power of the L-LLC resonant converter under different output voltages is different under this control strategy. The power output capability of the L-LLC resonant converter under the topology conversion control strategy can provide a reference basis for power control of the L-LLC resonant converter under different operating modes. Therefore, how to accurately analyze the power of the L-LLC resonant converter under the topology conversion control strategy is an important issue that needs to be solved in the industry. SUMMARY

[0005] The present application provides a power analysis method and system of an L-LLC resonant converter to solve the defect that the power of the L-LLC resonant converter under the topology conversion control strategy is not analyzed in the prior art, and to accurately analyze the power of the L-LLC resonant converter under the topology conversion control strategy.

[0006] The present application provides a power analysis method of an L-LLC resonant converter, comprising:

[0007] According to the boundary condition of each working mode of the L-LLC resonant converter under the variable topology control strategy, the expression of the normalized output power, and the boundary condition between each working mode and other working modes of the L-LLC resonant converter, the relationship between the normalized working frequency and the normalized output power of each working mode is obtained;

[0008] According to the range of the normalized working frequency of each working mode and the relationship between the normalized working frequency and the normalized output power of each working mode, the range of the normalized output power of each working mode is obtained;

[0009] According to the range of the normalized working frequency and the range of the normalized output power of each working mode, and the boundary condition and the expression of the normalized output power of each working mode, the range of the gain of each working mode is obtained;

[0010] According to the range of the normalized output power and the range of the gain of each working mode, and the relationship between the original output power of each working mode and the gain and the normalized output power of each working mode, the range of the original output power of each working mode is obtained.

[0011] According to the power analysis method of the L-LLC resonant converter provided by the application, when the original working frequency of the L-LLC resonant converter is less than the resonant frequency of the L-LLC resonant converter, the working mode of the L-LLC resonant converter in a half cycle includes POPN, POPO, POP, POOP, OPO and POO.

[0012] According to the power analysis method of the L-LLC resonant converter provided by the application, when the working mode includes three modes, the boundary condition of the working mode includes:

[0013] i rAn (0)=-i rCn (θ C ),v CrAn (0)=-v CrCn (θ C ),i mAn (0)=-i mCn (θ C );

[0014] i rAn (θ A )=i rBn (0),v CrAn (θ A )=v CrBn (0),i mAn (θ A )=i mBn (0);

[0015] i rBn (0) = i B (0), v rCn (0) = v CrBn (0), i B (0) = i CrCn (0), i mBn (0) = i B (0), i mCn (0) = i j (0);

[0016] wherein θ r = 2πf j t r , j is mode A, B or C, the working mode enters mode A, B and C in sequence, f j is the resonance frequency of the L-LLC resonant converter, t rjn is the time when the working mode enters mode j, i rjn (0) represents the normalized initial current of the resonant inductor in the L-LLC resonant converter corresponding to the mode j, i j (θ j ) represents the normalized current of the resonant inductor at θ Crjn (0) represents the normalized initial voltage of the resonant capacitor in the L-LLC resonant converter corresponding to the mode j, v Crjn (θ j ) represents the normalized voltage of the resonant capacitor at θ j (0) represents the normalized initial current of the excitation inductor in the L-LLC resonant converter corresponding to the mode j, i mjn (θ mjn ) represents the normalized current of the excitation inductor at θ j ;

[0017] When the working mode includes four modes, the boundary conditions of the working mode include:

[0018] i j (0) = -i rAn (θ rDn ), v D (0) = -v CrAn (θ CrDn ), i D (0) = -i mAn (θ mDn );

[0019] i D (θ rAn ) = i A (0).rBn (0), v CrAn (θ A ) = v CrBn (0), i mAn (θ A ) = i mBn (0);

[0020] i rBn (θ B ) = i rCn (0), v CrBn (θ B ) = v CrCn (0), i mBn (θ B ) = i mCn (0);

[0021] i rCn (θ C ) = i rDn (0), v CrCn (θ C ) = v CrDn (0), i mCn (θ C ) = i mDn (0);

[0022] wherein j is mode A, B, C or D, and the circuit of the operating mode enters modes A, B, C and D in sequence.

[0023] According to the power analysis method of the L-LLC resonant converter provided by the application, when the operating mode is POPO, mode A is a first mode P, mode B is a first mode O, mode C is a second mode P, and mode D is a second mode O; wherein the first mode P and the first mode O are respectively a forward excitation mode and a freewheeling mode of the L-LLC resonant converter when the input voltage is clamped, and the second mode P and the second mode O are respectively a forward excitation mode and a freewheeling mode of the L-LLC resonant converter when the input voltage is not clamped;

[0024] The circuit expression corresponding to the first mode P is:

[0025] i rPn1 (θ) = I rPn1 sin(θ+θ P01 )

[0026]

[0027]

[0028] wherein θ = 2πf r t, t is the time, i rPn1(θ) is the normalized current of the resonant inductance corresponding to the first mode P at θ, i mPn1 (θ) is the normalized current of the magnetizing inductance corresponding to the first mode P at θ, v CrPn1 (θ) is the normalized voltage of the resonant capacitance corresponding to the first mode P at θ, m = (L r + L m ) / L r , M = nV o / V i , L r is the inductance value of the resonant inductance, L m is the inductance value of the magnetizing inductance, n represents the ratio of the transformer in the L-LLC resonant converter, V o represents the output voltage of the L-LLC resonant converter, V i represents the input voltage of the L-LLC resonant converter;

[0029] The circuit expression corresponding to the first mode O is:

[0030]

[0031]

[0032]

[0033] wherein i rOn1 (θ) is the normalized current of the resonant inductance corresponding to the first mode O, i mOn1 (θ) is the normalized current of the magnetizing inductance corresponding to the first mode O, v CrOn1 is the normalized voltage of the resonant capacitance corresponding to the first mode O at θ, v mOn1 (θ) is the normalized voltage of the magnetizing inductance corresponding to the first mode O at θ;

[0034] The circuit expression corresponding to the second mode P is:

[0035] i rPn2 (θ) = I rPn1 sin(θ + θ P02 )

[0036]

[0037] v CrPn2 (θ) = -I rPn2 cos(θ + θ P02 ) + 1

[0038] wherein i rPn2(θ) is the normalized current of the resonant inductance corresponding to the second mode P at θ, i mPn2 (θ) is the normalized current of the magnetizing inductance corresponding to the second mode P at θ, v CrPn2 (θ) is the normalized voltage of the resonant capacitance corresponding to the second mode P at θ;

[0039] The circuit expression corresponding to the second mode O is:

[0040]

[0041]

[0042]

[0043] wherein i rOn2 (θ) is the normalized current of the resonant inductance corresponding to the second mode O at θ, i mOn2 (θ) is the normalized current of the magnetizing inductance corresponding to the second mode O at θ, v CrOn2 (θ) is the normalized voltage of the resonant capacitance corresponding to the second mode O at θ, v mOn2 (θ) is the normalized voltage of the magnetizing inductance corresponding to the second mode O at θ;

[0044] The mode N in the POPN is the negative excitation mode of the L-LLC resonant converter without input voltage clamping, and the corresponding circuit expression is:

[0045] i rNn (θ) = I rNn sin(θ + θ N0 )

[0046]

[0047] v CrNn (θ) = -I rNn cos(θ + θ N0 )-1

[0048] wherein i rNn (θ) is the normalized current of the resonant inductance corresponding to the mode N at θ, i mNn (θ) is the normalized current of the magnetizing inductance corresponding to the mode N at θ, v CrNn (θ) is the normalized voltage of the resonant capacitance corresponding to the mode N at θ; I rPnx , I mPnx , I rOnx , I mOnx , I rNn and I mNnLet x be the initial value of the corresponding current, where x is 1 or 2, and θ is... P01 θ P02 θ O01 θ O02 and θ N0 For the corresponding initial phase value, θ P1 θ P2 θ O1 θ O2 and θ N This represents the corresponding duration of the phase.

[0049] According to the power analysis method for an L-LLC resonant converter provided by the present invention, the boundary conditions between POPO and POPN are as follows:

[0050] v mNn (0)=(m-1)I rNn cos(0) = 1;

[0051] Among them, v mNn (0) is the normalized initial voltage value of the excitation inductor corresponding to the mode N, I rNn The initial value of the current in the resonant inductor corresponding to mode N;

[0052] The boundary conditions between POPO and POOP are as follows:

[0053] v mOn2 (0) = -1;

[0054] Among them, v mOn2 (0) is the normalized initial value of the excitation inductance corresponding to the second mode O;

[0055] The boundary conditions between POPO and POP are as follows:

[0056] i rPn2 (θ P2 ) = i mPn2 (θ P2 );

[0057] Where, θ P2 =2πf r t P2 , t P2 The moment when the operating mode enters the second mode P, i rPn2 (θ P2 ) represents the second mode P at θ P2 The normalized current i corresponding to the resonant inductor mPn2 (θ P2 ) represents the second mode P at θ P2 The normalized voltage of the corresponding resonant capacitor;

[0058] The boundary condition between the POPO and the OPO is:

[0059] v mOn1 (0)=1;

[0060] wherein v mOn1 (0) is a normalized voltage initial value of the resonant capacitor corresponding to the first mode O;

[0061] The boundary condition between the POOP and the POO is:

[0062] v mOn2 (θ O2 )=-1;

[0063] wherein θ O2 =2πf r t O2 , t O2 is the time when the working mode enters the second mode O, and v mOn2 (θ O2 ) is a normalized voltage of the resonant capacitor corresponding to the second mode O at θ O2 .

[0064] According to the power analysis method of the L-LLC resonant converter provided by the application, when the working mode is the POPN, the expression of the normalized output power is:

[0065]

[0066] wherein p on is the normalized output power, f n is the normalized working frequency, θ P =2πf r t P , θ N =2πf r t N , f r is the resonant frequency of the L-LLC resonant converter, t P and t N are respectively the time when the working mode enters the mode P and the mode N, i rPn and i rNn are respectively the normalized current of the resonant inductor in the L-LLC resonant converter corresponding to the mode P and the mode N, and i mPn and i mNn are respectively the normalized current of the excitation inductor in the L-LLC resonant converter corresponding to the mode P and the mode N.

[0067] According to the L-LLC resonant converter power analysis method provided by the application, the relationship between the original output power of each working mode and the gain, the normalized output power of each working mode is:

[0068]

[0069] Wherein, P o is the original output power, M is the gain, V i is the input voltage of the L-LLC resonant converter, p on is the normalized output power, Z r is the resonant impedance of the L-LLC resonant converter.

[0070] The application also provides an L-LLC resonant converter power analysis system, comprising:

[0071] The first acquisition module is configured to acquire the relationship between the normalized working frequency and the normalized output power of each working mode according to the boundary condition of each working mode of the L-LLC resonant converter under the variable topology control strategy, the expression of the normalized output power, and the boundary condition between each working mode and other working modes of the L-LLC resonant converter.

[0072] The second acquisition module is configured to acquire the range of the normalized output power of each working mode according to the range of the normalized working frequency of each working mode and the relationship between the normalized working frequency and the normalized output power of each working mode.

[0073] The third acquisition module is configured to acquire the range of the gain of each working mode according to the range of the normalized working frequency and the range of the normalized output power of each working mode, and the boundary condition and the expression of the normalized output power of each working mode.

[0074] The fourth acquisition module is configured to acquire the range of the original output power of each working mode according to the range of the normalized output power and the range of the gain of each working mode, and the relationship between the original output power of each working mode and the gain, the normalized output power of each working mode.

[0075] The application also provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the L-LLC resonant converter power analysis method according to any one of the above embodiments when executing the program.

[0076] The application further provides a non-transitory computer-readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the power analysis method of the L-LLC resonant converter.

[0077] The application further provides a computer program product, which comprises a computer program, and the computer program is executed by a processor to implement the steps of the power analysis method of the L-LLC resonant converter.

[0078] The application provides the power analysis method and system of the L-LLC resonant converter, the output power range and the gain range of each working mode under different loads are obtained by solving the nonlinear equations according to the boundary conditions of the L-LLC resonant converter under the variable topology control strategy and the output power equation, and the power output capability of the L-LLC resonant converter under different gains is obtained according to the output power range and the gain range, so that the power is limited in the working mode with good soft switching characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0079] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0080] Figure 1 It is a flowchart of the power analysis method of the L-LLC resonant converter provided by the application;

[0081] Figure 2 It is a full-bridge circuit topology diagram of the L-LLC resonant converter in the power analysis method of the L-LLC resonant converter provided by the application;

[0082] Figure 3 It is a boundary distribution diagram of f n and P on under different working modes in the power analysis method of the L-LLC resonant converter provided by the application;

[0083] Figure 4 It is a power output capability diagram of different gains in the power analysis method of the L-LLC resonant converter provided by the application;

[0084] Figure 5 It is a structural diagram of the power analysis system of the L-LLC resonant converter provided by the application;

[0085] Figure 6 It is a structural diagram of the electronic device provided by the application. DETAILED DESCRIPTION

[0086] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below with reference to the drawings in the present application. Obviously, the described embodiments are only some, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0087] The present application is described below with reference to the drawings Figure 1 The power analysis method of the L-LLC resonant converter is described, comprising: step 101, obtaining the relationship between the normalized operating frequency and the normalized output power of each operating mode according to the boundary conditions of each operating mode of the L-LLC resonant converter under the variable topology control strategy, the expression of the normalized output power, and the boundary conditions between each operating mode and other operating modes of the L-LLC resonant converter.

[0088] The present embodiment is applied to the L-LLC bidirectional isolated DC power electronic transformer under the variable topology control strategy. As shown in the figure, Figure 2 The L-LLC resonant converter comprises a primary side H-bridge, a medium-high frequency transformer, a secondary side H-bridge and a resonant network. The resonant network comprises a resonant inductor L r , a resonant capacitor C r , an excitation inductor L m1 and an auxiliary inductor L m2 , the transformation ratio of the medium-high frequency transformer is n:1, the primary side H-bridge comprises power switching tubes S1 to S4, and the secondary side H-bridge comprises power switching tubes S5 to S8. The midpoint of the power switching tube S1 and the power switching tube S2 is set as the A terminal, the midpoint of the power switching tube S3 and the power switching tube S4 is set as the B terminal, the midpoint of the power switching tube S5 and the power switching tube S6 is set as the C terminal, and the midpoint of the power switching tube S7 and the power switching tube S8 is set as the D terminal.

[0089] The variable topology control strategy refers to that the L-LLC resonant converter adopts the full-bridge mode when working in a higher gain range, and adopts the half-bridge mode when working in a lower gain range. The L-LLC resonant converter has multiple operating modes under the variable topology control strategy. Each operating mode is combined by multiple resonant modes according to the order of operation.

[0090] The resonant modes of the overall circuit of the L-LLC resonant converter are divided into three modes, i.e. mode P, mode N and mode O. When the input voltage is clamped, the resonant mode can be divided into three modes, i.e. V m1 , V m , V m = nV oP1, V m = -nV o N1, V m > -nV o O1, where n represents the transformer turns ratio, V o represents the output voltage. When the input voltage is clamped, the definitions of P and N are opposite to that when the input voltage is not clamped. m = -nV o P2, V m = nV o N2, V m < nV o O2.

[0091] Under the variable topology control strategy, the operating state of each mode of the L-LLC resonant converter is affected by the boundary conditions of its adjacent modes and the switching time. Since the capacitor voltage and the inductor current are continuous in two stages, the operating stage of each mode is divided into three stages (such as POP) and four stages (such as POPO) to analyze the boundary conditions of each mode and the boundary conditions between modes.

[0092] As in the POPO mode, the four stages are divided into P1, O1, P2 and O2 for analysis, indicating that the overall circuit first operates in the P1 mode, 1 / 4T s ends and enters the O1 mode, 1 / 4T s enters the P2 mode, and finally enters the O2 mode again before 1 / 2T s ends, T s represents half a period, and other modes are similar.

[0093] In order to simplify the analysis, the equations and expressions are processed with normalized variables. Among them, the normalized operating frequency f n = f s / f r , the normalized voltage variable v n = v / nV o , the normalized current variable i n = i / (nV o / Z r ), the normalized output power Z r is the resonant impedance, P o is the output power, L r is the inductance value of the resonant inductor, and C r is the capacitance value of the resonant capacitor.

[0094] The L-LLC resonant converter operates in variable topology mode, and the maximum output power under different output voltages depends on the working mode boundary. By solving the nonlinear equation set through the simultaneous equations of the boundary conditions of each working mode, the boundary conditions between working modes, and the normalized output power, the normalized working frequency f n and the relationship of p on .

[0095] Step 102, according to the range of the normalized working frequency of each working mode, and the relationship between the normalized working frequency and the normalized output power of each working mode, the range of the normalized output power of each working mode is obtained;

[0096] The range of the normalized working frequency f n of each working mode is known, the boundary value of the normalized working frequency is input into the relationship equation between the normalized working frequency f n and the normalized output power P on , and the boundary value of the normalized output power P on is obtained. The boundary distribution diagram of f n and P on under different working modes is shown in Figure 3 .

[0097] Step 103, according to the range of the normalized working frequency and the range of the normalized output power of each working mode, and the boundary condition and the expression of the normalized output power of each working mode, the range of the gain of each working mode is obtained;

[0098] By simultaneously solving the expression of the normalized output power and the boundary condition of the working mode, in the case of known p on and f n , enough equations can be found to solve the gain M and the initial value of each working mode.

[0099] Step 104, according to the range of the normalized output power and the range of the gain of each working mode, and the relationship between the original output power of each working mode and the gain, the normalized output power of each working mode, the range of the original output power of each working mode is obtained.

[0100] The boundary value of the normalized output power P on and the boundary value of the gain M are input into the relationship equation between the original output power P o and the gain M, the normalized output power P on of each working mode, and the boundary value of the original output power P o is obtained, which can be used for power boundary judgment of different working modes.

[0101] FromFigure 4 It can be seen that when the L-LLC resonant converter is at m=14, the maximum output power allowed by the L-LLC resonant converter under different voltage gain outputs can be ensured under the premise of guaranteeing the soft switching characteristic.

[0102] The embodiment obtains the output power range and the gain range of each working mode under different loads by solving the nonlinear equation set according to the boundary conditions of the working modes of the L-LLC resonant converter under the variable topology control strategy and the output power equation, and obtains the power output capability of the L-LLC resonant converter under different gains according to the output power range and the gain range, so as to ensure that the power is limited in the working mode with good soft switching characteristic.

[0103] On the basis of the above embodiment, in the embodiment, when the original working frequency f s of the L-LLC resonant converter is less than the resonant frequency f r of the L-LLC resonant converter, the working modes of the L-LLC resonant converter in a half cycle include POPN, POPO, POP, POOP, OPO and POO.

[0104] Under the variable topology control strategy of the L-LLC resonant converter, different combinations of three resonant modes in a half cycle form different working modes.

[0105] Generally, when the original working frequency f s is lower than the resonant frequency f r , there are six working modes, namely, POPN, POPO, POP, POOP, OPO and POO. In each working mode, the modes are arranged in the order of operation.

[0106] On the basis of the above embodiment, in the embodiment, when the working mode includes three modes, the boundary conditions of the working mode include:

[0107] i rAn (0)=-i rCn (θ C ),v CrAn (0)=-v CrCn (θ C ),i mAn (0)=-i mCn (θ C );

[0108] i rAn (θ A )=i rBn (0),v CrAn (θ A )=v CrBn (0),i mAn(θ A ) = i mBn (0);

[0109] i rBn (θ B ) = i rCn (0), v CrBn (θ B ) = v CrCn (0), i mBn (θ B ) = i mCn (0);

[0110] where θ j = 2πf r t j , j is mode A, B or C, the working mode circuit enters mode A, B and C in turn, f r is the resonance frequency of the L-LLC resonant converter, t j is the time when the working mode enters mode j, i rjn (0) represents the normalized initial current of the resonant inductor in the L-LLC resonant converter corresponding to the mode j, i rjn (θ j ) represents the normalized current of the resonant inductor at θ j corresponding to the mode j, v Crjn (0) represents the normalized initial voltage of the resonant capacitor in the L-LLC resonant converter corresponding to the mode j, v Crjn (θ j ) represents the normalized voltage of the resonant capacitor at θ j corresponding to the mode j, i mjn (0) represents the normalized initial current of the excitation inductor in the L-LLC resonant converter corresponding to the mode j, i mjn (θ j ) represents the normalized current of the excitation inductor at θ j corresponding to the mode j;

[0111] When the working mode includes four modes, the boundary conditions of the working mode include:

[0112] i rAn (0) = -i rDn (θ D ), v CrAn (0) = -v CrDn (θ D ), i mAn (0) = -i mDn (θ D );

[0113] irAn (θ A )=i rBn (0),v CrAn (θ A )=v CrBn (0),i mAn (θ A )=i mBn (0);

[0114] i rBn (θ B )=i rCn (0),v CrBn (θ B )=v CrCn (0),i mBn (θ B )=i mCn (0);

[0115] i rCn (θ C )=i rDn (0),v CrCn (θ C )=v CrDn (0),i mCn (θ C )=i mDn (0);

[0116] wherein j is mode A, B, C or D, the circuit of the working mode enters mode A, B, C and D in turn.

[0117] It should be noted that in the embodiment, the first entered mode in each working mode is denoted as mode A, the second entered mode is denoted as mode B, the third entered mode is denoted as mode C, and the fourth entered mode is denoted as mode D. For example, mode A in working mode OPO is mode O, and mode A in working mode POO is mode P.

[0118] On the basis of the above embodiment, in the embodiment, when the working mode is POPO, mode A is the first mode P, mode B is the first mode O, mode C is the second mode P, and mode D is the second mode O; wherein the first mode P and the first mode O are respectively the forward excitation mode and the freewheeling mode of the L-LLC resonant converter when the input voltage is clamped, and the second mode P and the second mode O are respectively the forward excitation mode and the freewheeling mode of the L-LLC resonant converter when the input voltage is not clamped;

[0119] The circuit expression corresponding to the first mode P is:

[0120] i rPn1 (θ)=I rPn1 sin(θ+θP01 )

[0121]

[0122]

[0123] where θ = 2πf r t, t is time, i rPn1 (θ) is the normalized current of the resonant inductance corresponding to the first mode P at θ, i mPn1 (θ) is the normalized current of the magnetizing inductance corresponding to the first mode P at θ, v CrPn1 (θ) is the normalized voltage of the resonant capacitance corresponding to the first mode P at θ, m = (L r + L m ) / L r , M = nV o / V i , L r is the inductance value of the resonant inductance, L m is the inductance value of the magnetizing inductance, n represents the ratio of the transformer in the L-LLC resonant converter, V o represents the output voltage of the L-LLC resonant converter, V i represents the input voltage of the L-LLC resonant converter;

[0124] The circuit expression corresponding to the first mode O is:

[0125]

[0126]

[0127]

[0128] where i rOn1 (θ) is the normalized current of the resonant inductance corresponding to the first mode O, i mOn1 (θ) is the normalized current of the magnetizing inductance corresponding to the first mode O, v CrOn1 is the normalized voltage of the resonant capacitance corresponding to the first mode O at θ, v mOn1 (θ) is the normalized voltage of the magnetizing inductance corresponding to the first mode O at θ;

[0129] The circuit expression corresponding to the second mode P is:

[0130] i rPn2 (θ) = I rPn1 sin(θ + θ P02 )

[0131]

[0132] v CrPn2 (θ)=-I rPn2 cos(θ+θ P02 )+1

[0133] where i rPn2 (θ) is the normalized current of the resonant inductance corresponding to the second mode P at θ, i mPn2 (θ) is the normalized current of the excitation inductance corresponding to the second mode P at θ, v CrPn2 (θ) is the normalized voltage of the resonant capacitance corresponding to the second mode P at θ;

[0134] The circuit expression corresponding to the second mode O is:

[0135]

[0136]

[0137]

[0138] where i rOn2 (θ) is the normalized current of the resonant inductance corresponding to the second mode O, i mOn2 (θ) is the normalized current of the excitation inductance corresponding to the second mode O, v CrOn2 (θ) is the normalized voltage of the resonant capacitance corresponding to the second mode O at θ, v mOn2 (θ) is the normalized voltage of the excitation inductance corresponding to the second mode O at θ;

[0139] The mode N in the POPN is a negative excitation mode when the auxiliary inductance has no input voltage clamping, and the corresponding circuit expression is:

[0140] i rNn (θ)=I rNn sin(θ+θ N0 )

[0141]

[0142] v CrNn (θ)=-I rNn cos(θ+θ N0 )-1

[0143] where i rNn (θ) is the normalized current of the resonant inductance corresponding to the mode N at θ, i mNnv (0) = (m-1)I (0) cos(0) = 1 CrNn v (0) = (m-1)I (0) cos(0) = 1 rPnx v (0) = (m-1)I (0) cos(0) = 1 mPnx v (0) = (m-1)I (0) cos(0) = 1 rOnx v (0) = (m-1)I (0) cos(0) = 1 mOnx v (0) = (m-1)I (0) cos(0) = 1 rNn v (0) = (m-1)I (0) cos(0) = 1 mNn v (0) = (m-1)I (0) cos(0) = 1 P01 v (0) = (m-1)I (0) cos(0) = 1 P02 v (0) = (m-1)I (0) cos(0) = 1 O01 v (0) = (m-1)I (0) cos(0) = 1 O02 v (0) = (m-1)I (0) cos(0) = 1 N0 v (0) = (m-1)I (0) cos(0) = 1 P1 v (0) = (m-1)I (0) cos(0) = 1 P2 v (0) = (m-1)I (0) cos(0) = 1 O1 v (0) = (m-1)I (0) cos(0) = 1 O2 v (0) = (m-1)I (0) cos(0) = 1 N v (0) = (m-1)I (0) cos(0) = 1

[0144] On the basis of the above embodiment, the boundary condition between the POPO and the POPN in the present embodiment is:

[0145] v (0) = (m-1)I (0) cos(0) = 1 mNn v (0) = (m-1)I (0) cos(0) = 1 rNn v (0) = (m-1)I (0) cos(0) = 1

[0146] v (0) = (m-1)I (0) cos(0) = 1 mNn v (0) = (m-1)I (0) cos(0) = 1 rNn v (0) = (m-1)I (0) cos(0) = 1

[0147] Under the variable topology control strategy, as the load power increases, the duration of the mode O of the LLC resonant converter decreases, and when the load power increases to a heavy condition, the O mode disappears, and the circuit mode changes from POPO to POPN. The difference lies in the last stage, the excitation voltage v m across the two ends is always less than nV o , while v m across the two ends is always nV o , thereby analyzing the boundary condition between POPO and POPN.

[0148] The boundary condition between the POPO and the POPN in the present embodiment is:

[0149] v (0) = (m-1)I (0) cos(0) = 1 mOn2 v (0) = (m-1)I (0) cos(0) = 1

[0150] v (0) = (m-1)I (0) cos(0) = 1 mOn2 v (0) = (m-1)I (0) cos(0) = 1

[0151] The difference between patterns POPO and POOP lies in the third phase. When it is phase P, v m Initially -nV o When it is stage O, v m Initially greater than -nV o This allows us to analyze the boundary conditions between POPO and POOP.

[0152] The boundary conditions between POPO and POP are as follows:

[0153] i rPn2 (θ P2 ) = i mPn2 (θ P2 );

[0154] Where, θ P2 =2πf r t P2 , t P2 The moment when the operating mode enters the second mode P, i rPn2 (θ P2 ) represents the second mode P at θ P2 The normalized current i corresponding to the resonant inductor mPn2 (θ P2 ) represents the second mode P at θ P2 The normalized voltage of the corresponding resonant capacitor;

[0155] The difference between modes POPO and POP lies in the presence or absence of a fourth stage. Under boundary conditions, the resonant current i in stage P2 at the half-cycle endpoint is... rPn2 and excitation current i mPn2 They are equal, thus the boundary conditions between POPO and POP can be analyzed.

[0156] The boundary conditions between POPO and OPO are as follows:

[0157] v mOn1 (0) = 1;

[0158] Among them, v mOn1 (0) The normalized initial voltage value of the resonant capacitor corresponding to the first mode O;

[0159] The difference between POPO and OPO modes lies in the first stage. In OPO mode, at the start of the first stage O1, the voltage v across the excitation terminals... m Always less than nV o The voltage v across the P1 excitation terminals of POPO in the first stage m Always equal to nV o This allows us to analyze the boundary conditions between POPO and OPO.

[0160] The boundary condition between the POOP and the POO is:

[0161] v mOn2 (θ O2 ) = -1

[0162] where θ O2 = 2πf r t O2 , t O2 is the time when the operating mode enters the second mode O, and v mOn2 (θ O2 ) is the normalized voltage of the resonant capacitor corresponding to the second mode O at θ O2 .

[0163] The difference between the mode POOP and the mode POO lies in the last stage. The excitation voltage v m is always nV o when entering the P1 stage, and the excitation voltage v m is always -nV o when entering the P2 stage, so that the boundary condition between the POOP and the POO is analyzed.

[0164] On the basis of the above embodiment, when the operating mode is the POPN in the embodiment, the expression of the normalized output power is:

[0165]

[0166] where p on is the normalized output power, f n is the normalized operating frequency, θ P = 2πf r t P , θ N = 2πf r t N , f r is the resonant frequency of the L-LLC resonant converter, t P and t N are the times when the operating mode enters the mode P and the mode N, respectively, i rPn and i rNn are the normalized currents of the resonant inductance in the L-LLC resonant converter corresponding to the mode P and the mode N, respectively, and i mPn and i mNn are the normalized currents of the excitation inductance in the L-LLC resonant converter corresponding to the mode P and the mode N, respectively.

[0167] For the POPN operating mode, since the output current stops in stage O, only stages P and N involve energy transfer, thus yielding the normalized output power of the L-LLC resonant converter.

[0168] Based on the above embodiments, the relationship between the original output power of each operating mode and the gain and normalized output power of each operating mode in this embodiment is as follows:

[0169]

[0170] Among them, P o Where M is the original output power, and V is the gain. i p is the input voltage of the L-LLC resonant converter. on Z is the normalized output power. r The resonant impedance of the L-LLC resonant converter is given.

[0171] The power analysis system for the L-LLC resonant converter provided by this invention is described below. The power analysis system for the L-LLC resonant converter described below can be referred to in correspondence with the power analysis method for the L-LLC resonant converter described above.

[0172] like Figure 5 As shown, the system includes a first acquisition module 501, a second acquisition module 502, a third acquisition module 503, and a fourth acquisition module 504, wherein:

[0173] The first acquisition module 501 is used to acquire the relationship between the normalized operating frequency and the normalized output power of each operating mode based on the boundary conditions of each operating mode of the L-LLC resonant converter under the variable topology control strategy, the expression of the normalized output power, and the boundary conditions between each operating mode and other operating modes of the L-LLC resonant converter.

[0174] The second acquisition module 502 is used to acquire the range of normalized output power for each working mode based on the range of normalized operating frequency for each working mode and the relationship between normalized operating frequency and normalized output power for each working mode.

[0175] The third acquisition module 503 is used to acquire the gain range of each operating mode based on the range of normalized operating frequency and the range of normalized output power of each operating mode, as well as the boundary conditions and the expression of normalized output power of each operating mode.

[0176] The fourth acquisition module 504 is configured to acquire a range of the original output power of each working mode according to the range of the normalized output power and the range of the gain of each working mode, and the relationship between the original output power of each working mode and the gain, the normalized output power of each working mode.

[0177] The embodiment obtains the output power range and the gain range of each working mode under different loads by solving the nonlinear equation set according to the boundary conditions of the working modes and the output power equation of the L-LLC resonant converter under the variable topology control strategy, and obtains the power output capability of the L-LLC resonant converter under different gains according to the output power range and the gain range, so as to ensure that the power is limited in the working mode with good soft switching characteristics.

[0178] Figure 6 An example of an entity structure diagram of an electronic device is shown in Figure 6 As shown in the figure, the electronic device can include a processor 610, a communications interface 620, a memory 630 and a communications bus 640, wherein the processor 610, the communications interface 620 and the memory 630 complete mutual communication through the communications bus 640. The processor 610 can call the logic instructions in the memory 630 to execute the power analysis method of the L-LLC resonant converter, which includes: acquiring the relationship between the normalized working frequency and the normalized output power of each working mode according to the boundary conditions of the working modes and the expression of the normalized output power; acquiring the range of the normalized output power of each working mode according to the range of the normalized working frequency of each working mode and the relationship; substituting the range of the normalized working frequency and the range of the normalized output power of each working mode into the boundary conditions of each working mode and the expression of the normalized output power to solve the range of the gain; and acquiring the range of the original output power of each working mode according to the range of the normalized output power and the range of the gain.

[0179] Further, the logic instructions in the memory 630 described above can be implemented in the form of software functional units and sold or used as independent products, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the parts that make contributions to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0180] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor to enable a computer to perform the power analysis method of the L-LLC resonant converter provided by the above-mentioned methods, the method comprising: obtaining the relationship between the normalized operating frequency and the normalized output power of each operating mode according to the boundary condition of the operating mode and the expression of the normalized output power; obtaining the range of the normalized output power of each operating mode according to the range of the normalized operating frequency of each operating mode and the relationship; substituting the range of the normalized operating frequency and the range of the normalized output power of each operating mode into the boundary condition of each operating mode and the expression of the normalized output power to solve the range of the gain; and obtaining the original output power range of each operating mode according to the range of the normalized output power and the range of the gain.

[0181] In another aspect, the present application also provides a non-transitory computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the power analysis method of the L-LLC resonant converter provided by the above-mentioned methods, the method comprising: obtaining the relationship between the normalized operating frequency and the normalized output power of each operating mode according to the boundary condition of the operating mode and the expression of the normalized output power; obtaining the range of the normalized output power of each operating mode according to the range of the normalized operating frequency of each operating mode and the relationship; substituting the range of the normalized operating frequency and the range of the normalized output power of each operating mode into the boundary condition of each operating mode and the expression of the normalized output power to solve the range of the gain; and obtaining the original output power range of each operating mode according to the range of the normalized output power and the range of the gain.

[0182] The system embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed to multiple network units. Part or all of the modules can be selected to achieve the purposes of the embodiments according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0183] Through the description of the above embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and the necessary general hardware platform, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0184] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A power analysis method of an L-LLC resonant converter, characterized by, Comprising: In the case that the original operating frequency of the L-LLC resonant converter is less than the resonant frequency of the L-LLC resonant converter, the operating mode of the L-LLC resonant converter in a half cycle comprises POPN, POPO, POP, POOP, OPO and POO; According to the boundary condition of each operating mode of the L-LLC resonant converter under the variable topology control strategy, the expression of the normalized output power, and the boundary condition between each operating mode and other operating modes of the L-LLC resonant converter, the relationship between the normalized operating frequency and the normalized output power of each operating mode is obtained; According to the range of the normalized operating frequency of each operating mode and the relationship between the normalized operating frequency and the normalized output power of each operating mode, the range of the normalized output power of each operating mode is obtained; According to the range of the normalized operating frequency and the range of the normalized output power of each operating mode, and the boundary condition and the expression of the normalized output power of each operating mode, the range of the gain of each operating mode is obtained; According to the range of the normalized output power and the range of the gain of each operating mode, and the relationship between the original output power of each operating mode and the gain and the normalized output power of each operating mode, the range of the original output power of each operating mode is obtained; wherein the relationship between the original output power of each operating mode and the gain and the normalized output power of each operating mode is: where P o is the original output power, M is the gain, V i is the input voltage of the L-LLC resonant converter, p on is the normalized output power, Z r is the resonant impedance of the L-LLC resonant converter.

2. The power analysis method of an L-LLC resonant converter according to claim 1, characterized in that, When the operating mode comprises three modes, the boundary condition of the operating mode comprises: i rAn (0) = -i rCn (θ C ), v CrAn (0) = -v CrCn (θ C ), i mAn (0) = -i mCn (θ C ); i rAn (θ A )=i rBn (0), v CrAn (θ A )=v CrBn (0), i mAn (θ A )=i mBn (0); i rBn (θ B )=i rCn (0), v CrBn (θ B )=v CrCn (0), i mBn (θ B )=i mCn (0); wherein θ j = 2πf r t j , j is mode A, B or C, the circuit of the operating mode enters mode A, B and C in turn, f r is the resonance frequency of the L-LLC resonant converter, t j is the time when the operating mode enters mode j, i rjn (0) represents the normalized initial current of the resonant inductor in the L-LLC resonant converter corresponding to the mode j, i rjn (θ j ) represents the normalized current of the resonant inductor corresponding to the mode j at θ j , v Crjn (0) represents the normalized initial voltage of the resonant capacitor in the L-LLC resonant converter corresponding to the mode j, v Crjn (θ j ) represents the normalized voltage of the resonant capacitor corresponding to the mode j at θ j , i mjn (0) represents the normalized initial current of the magnetizing inductor in the L-LLC resonant converter corresponding to the mode j, i mjn (θ j ) represents the normalized current of the magnetizing inductor corresponding to the mode j at θ j ; When the operating mode comprises four modes, the boundary condition of the operating mode comprises: i rAn (0) = -i rDn (θ D ), v CrAn (0) = -v CrDn (θ D ), i mAn (0) = -i mDn (θ D ); i rAn (θ A )=i rBn (0), v CrAn (θ A )=v CrBn (0), i mAn (θ A )=i mBn (0); i rBn (θ B )=i rCn (0), v CrBn (θ B )=v CrCn (0), i mBn (θ B )=i mCn (0); i rCn (θ C )=i rDn (0),v CrCn (θ C )=v CrDn (0),i mCn (θ C )=i mDn (0); Wherein, j is mode A, B, C or D, and the circuit of the operating mode enters mode A, B, C and D in turn.

3. The power analysis method of an L-LLC resonant converter according to claim 2, characterized in that, When the operating mode is POPO, mode A is the first mode P, mode B is the first mode O, mode C is the second mode P, and mode D is the second mode O; wherein the first mode P and the first mode O are the forward excitation mode and the freewheeling mode of the L-LLC resonant converter when the input voltage is clamped, respectively, and the second mode P and the second mode O are the forward excitation mode and the freewheeling mode of the L-LLC resonant converter when the input voltage is not clamped, respectively; The circuit expression corresponding to the first mode P is: wherein θ = 2πf r t, t is time, i rPn1 (θ) is the normalized current of the resonant inductance corresponding to the first mode P at θ, i mPn1 (θ) is the normalized current of the magnetizing inductance corresponding to the first mode P at θ, v CrPn1 (θ) is the normalized voltage of the resonant capacitance corresponding to the first mode P at θ, m = (L r + L m ) / L r , M = nV o / V i , L r is the inductance value of the resonant inductance, L m is the inductance value of the magnetizing inductance, n represents the ratio of the transformer in the L-LLC resonant converter, V o represents the output voltage of the L-LLC resonant converter, V i represents the input voltage of the L-LLC resonant converter; The circuit expression corresponding to the first mode O is: wherein, i rOn1 (θ) is the normalized current of the resonant inductance corresponding to the first mode O, i mOn1 (θ) is the normalized current of the excitation inductance corresponding to the first mode O, v CrOn1 (θ) is the normalized voltage of the resonant capacitance corresponding to the first mode O at θ, v mOn1 (θ) is the normalized voltage of the excitation inductance corresponding to the first mode O at θ. The circuit expression corresponding to the second mode P is: wherein, i rPn2 (0) is the normalized current of the resonant inductance corresponding to the second mode P at 0 mPn2 (0) is the normalized current of the excitation inductance corresponding to the second mode P at 0 CrPn2 (0) is the normalized voltage of the resonant capacitance corresponding to the second mode P at 0 The circuit expression corresponding to the second mode O is: wherein, i rOn2 (0) is the normalized current of the resonant inductance corresponding to the second mode O, i mOn2 (0) is the normalized current of the excitation inductance corresponding to the second mode O, v CrOn2 (0) is the normalized voltage of the resonant capacitance corresponding to the second mode O at 0, v mOn2 (0) is the normalized voltage of the excitation inductance corresponding to the second mode O at 0. The mode N in the POPN is the negative excitation mode of the L-LLC resonant converter when the input voltage is not clamped, and the corresponding circuit expression is: where i rNn (θ) is the normalized current of the resonant inductance corresponding to the mode N at θ, i mNn (θ) is the normalized current of the excitation inductance corresponding to the mode N at θ, v CrNn (θ) is the normalized voltage of the resonant capacitance corresponding to the mode N at θ; I rPnx , I mPnx , I rOnx , I mOnx , I rNn and I mNn are the corresponding initial currents, x is 1 or 2, θ P01 , θ P02 , θ O01 , θ O02 and θ N0 are the corresponding initial phases, θ P1 , θ P2 , θ O1 , θ O2 and θ N are the corresponding duration phase lengths.

4. The power analysis method of an L-LLC resonant converter according to claim 3, characterized in that, The boundary condition between the POPO and the POPN is: v mNn (0) = (m - 1) I rNn cos(0) = 1; wherein v mNn (0) is the normalized voltage initial value of the excitation inductance corresponding to the mode N, I rNn is the current initial value of the resonance inductance corresponding to the mode N; The boundary condition between the POPO and the POOP is: v mOn2 (0)＝-1； wherein v mOn2 (0) is the normalized voltage initial value of the excitation inductance corresponding to the second modality O; The boundary condition between the POPO and the POP is: i rPn2 (θ P2 )=i mPn2 (θ P2 ); where θ P2 = 2πf r t P2 , t P2 is the time instant when the operating mode enters the second regime P, i rPn2 (θ P2 ) is the normalized current of the resonant inductance corresponding to the second regime P at θ P2 , i mPn2 (θ P2 ) is the normalized voltage of the resonant capacitance corresponding to the second regime P at θ P2 . The boundary condition between the POPO and the OPO is: v mOn1 (0)＝1； wherein v mOn1 (0) is the normalized voltage initial value of the resonance capacitor corresponding to the first mode O; The boundary condition between the POOP and the POO is: v mOn2 (θ O2 )=-1; where θ O2 = 2πf r t O2 , t O2 is the time instant at which the operating mode enters the second regime O, v mOn2 (θ O2 ) is the normalized voltage of the resonance capacitor corresponding to the second regime O at θ O2 .

5. The power analysis method of an L-LLC resonant converter according to any one of claims 1-4, characterized in that, When the operating mode is POPN, the expression of the normalized output power is: where p on is the normalized output power, f n is the normalized operating frequency, θ P = 2πf r t P , θ N = 2πf r t N , f r is the resonant frequency of the L-LLC resonant converter, t P and t N are the instants when the operating mode enters the mode P and mode N, respectively, i rPn and i rNn are the normalized currents of the resonant inductance in the L-LLC resonant converter corresponding to the mode P and mode N, respectively, i mPn and i mNn are the normalized currents of the magnetizing inductance in the L-LLC resonant converter corresponding to the mode P and mode N, respectively.

6. A power analysis system for an L-LLC resonant converter, characterized by, Comprising: The first obtaining module, in the case that the original operating frequency of the L-LLC resonant converter is less than the resonant frequency of the L-LLC resonant converter, the operating mode of the L-LLC resonant converter in a half cycle includes POPN, POPO, POP, POOP, OPO and POO; the relationship between the normalized operating frequency and the normalized output power of each operating mode is obtained according to the boundary condition of each operating mode of the L-LLC resonant converter under the variable topology control strategy, the expression of the normalized output power, and the boundary condition between each operating mode and other operating modes of the L-LLC resonant converter; The second obtaining module is configured to obtain the range of the normalized output power of each operating mode according to the range of the normalized operating frequency of each operating mode and the relationship between the normalized operating frequency and the normalized output power of each operating mode; The third obtaining module is configured to obtain the range of the gain of each operating mode according to the range of the normalized operating frequency and the range of the normalized output power of each operating mode, and the boundary condition and the expression of the normalized output power of each operating mode; The fourth obtaining module is configured to obtain the range of the original output power of each operating mode according to the range of the normalized output power and the range of the gain of each operating mode, and the relationship between the original output power of each operating mode and the gain and the normalized output power of each operating mode, wherein the relationship between the original output power of each operating mode and the gain and the normalized output power of each operating mode is: where P o is the original output power, M is the gain, V i is the input voltage of the L-LLC resonant converter, p on is the normalized output power, Z r is the resonant impedance of the L-LLC resonant converter.

7. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the steps of the power analysis method of the L-LLC resonant converter according to any one of claims 1 to 5 when executing the program.

8. A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program implements the steps of the power analysis method of the L-LLC resonant converter according to any one of claims 1 to 5 when executed by the processor.

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