CN114417767B - DAB inductance loss calculation method based on inductance current characteristic value - Google Patents
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Abstract
The invention discloses a DAB inductance loss calculation method based on an inductance current characteristic value, which optimizes an iGSE method for calculating the magnetic core loss by calculating the inductance current characteristic value aiming at the inductance loss and the temperature rise of a double-active bridge DAB circuit, provides a current-based iGSE magnetic core loss calculation method and provides a current-based winding loss expression. The invention finally provides a method for calculating the total loss of the DAB inductor through the characteristic value of the inductor current, solves the problems of long time consumption and complex calculation of the inductor loss calculation, simultaneously provides an inductor loss calculation method with higher calculation accuracy for the DAB circuit, is convenient for a designer to realize accurate estimation of the inductor temperature rise in the design process, and ensures the operation reliability of a DAB practical device.
Description
Technical Field
The invention belongs to the field of design verification of power electronic converters, and particularly relates to a DAB inductance loss calculation method based on an inductance current characteristic value.
Background
Compared with the traditional transformer, the power electronic transformer has the advantages of high working efficiency, small volume, controllable output and the like. The double active bridge (DualActive Bridge, DAB) was proposed by De Doncker in 1992, and has become a common topology for power transmission stages of medium-high power electronic converters due to the advantages of high power density, simple control, and simpler implementation of zero voltage switching on. A typical topology of DAB includes a DC/AC link, an AC/DC link, a transformer and an inductor.
The power devices of the traditional DAB circuit mostly use silicon devices, the switching frequency and rated power of the silicon devices are low, and further improvement of the power density of the DAB circuit is limited. In recent years, third generation power semiconductor devices mainly comprising Silicon carbide (SiC) devices have been rapidly developed, and more DAB has selected to use SiC devices to increase the transmission power and the operating frequency of the device. But as frequency and power increase, so does the loss of inductance. When the total loss of the inductor reaches a certain degree, the temperature of the magnetic core exceeds the upper temperature limit which can work normally. In this case, the inductor core may be damaged while DAB does not work properly. Therefore, for the high-frequency high-power DAB device, the accurate prediction of the loss and the temperature rise of the inductor in design is of great importance.
The inductance in DAB generates two losses during operation, core loss and winding loss. For the calculation of core loss, the currently prevailing estimation models are the physical model, the loss surface model and the Steinmetz formula model. Compared with other models, the Steinmetz formula model is a mainstream mode for estimating the magnetic core loss of the magnetic material at present because of the advantages of simple parameter acquisition, no need of complex measurement, convenient calculation and the like. At present, various specific methods for calculating the magnetic core loss are generated based on a Steinmetz formula model, including correction of Steinmetz equation (Modified Steinmetz Equation, MSE), generalized Steinmetz equation (Generalized Steinmetz Equation, GSE) and modified generalized Steinmetz equation (improved Generalized Steinmetz Equation, iGSE), wherein the iGSE model simultaneously considers the maximum magnetic flux density and the waveform of the magnetic flux density changing in one period, and divides the magnetic flux curve of one period into a plurality of magnetic flux loops, so that the defects of poor calculation accuracy, poor calculation stability and the like in other methods are overcome, and therefore, the iGSE is the most commonly used calculation method for calculating the magnetic core loss of the magnetic material. However, since the iGSE includes a process of separating the magnetic flux curves, which often requires a lot of computation effort and time, the original iGSE method is not an optimal method for calculating the inductance core loss in DAB. For winding loss calculation, an algorithm of inductance core and winding loss based on closed loop solution is proposed, but the method is based on a single-phase boost PFC rectifier and cannot be directly applied to a DAB circuit.
Disclosure of Invention
The invention aims to provide a DAB inductance loss calculation method based on an inductance current characteristic value, so as to solve the defects of the existing inductance loss calculation method aiming at a DAB circuit. The method has the advantages of less required parameters, higher accuracy, no huge calculated amount and calculation time, and suitability for testing and verifying the reliability of the inductance design by all designers in the field.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a DAB inductance loss calculation method based on inductance current characteristic values comprises the following steps:
s1: calculating a DAB inductance current characteristic value;
s2: obtaining an improved generalized Steinotz equation based on current according to the characteristic value of the inductance current, and calculating the magnetic core loss of the inductance by utilizing the improved generalized Steinotz equation based on current;
s3: obtaining an inductance current effective value calculation formula according to the inductance current characteristic value, and calculating the winding loss of the inductor according to the inductance current effective value calculation formula;
s4: and according to the magnetic core loss and the winding loss in S2 and S3, obtaining an inductance total loss expression and a temperature rise expression of the inductance during operation.
Further, the calculating of the DAB inductor current characteristic value in S1 specifically includes the following steps:
s11: obtaining the relation of the characteristic values of the inductor current flowing through Cheng Shimo of the primary side and the secondary side of the DAB transformer according to the technical index of the DAB circuit and the selected device parameters;
s12: according to the principle of primary and secondary side commutation process, an equivalent resonance circuit and an equivalent resonance process of the DAB commutation process are obtained;
s13: according to the equivalent resonant circuit and the corresponding equivalent resonant process, obtaining the time relation of the primary side and the secondary side of the DAB transformer in the conversion process by a vector track method;
s14: obtaining a change relation between inductance current characteristic values in a non-commutation process according to DAB circuit technical indexes;
s15: and (3) finding out a group of inductor current characteristic values which fully meet the relationship of inductor current characteristic values of the current through Cheng Shimo in S11, the relationship of primary and secondary side current conversion process time in S13 and the relationship of non-current through Cheng Diangan in S14 through a traversal algorithm.
Further, the relation between the secondary side of the DAB transformer and the characteristic value of the inductor current flowing through Cheng Shimo in S11 is as follows:
wherein L represents DAB inductance value, I L1 The induction current value at the initial moment of the secondary side exchange process is shown, and the 1 st induction current characteristic value is also shown, I L2 The inductor current value at the end of the secondary side commutation process is represented, and the 2 nd inductor current characteristic value is also represented, V s Representing the equivalent power supply voltage of the secondary side of the transformer and V in the secondary side converter process s ＝V in N, n represents the transformer transformation ratio, 2Q oss (V out ) Representing the secondary equivalent power V of the slave transformer s Total amount of electric charge flowing out, V out Represents DAB output voltage, C oss (v) Output capacitance of the power device under different voltages is represented;
the relation between the primary side commutated Cheng Shimo inductance current characteristic values of the DAB transformer in the S11 is as follows:
wherein I is L3 The inductor current value at the initial moment of the primary side exchange process is represented, and the characteristic value of the 3 rd inductor current is also represented, I L4 The inductor current value at the end of the primary side commutation process is represented, and the 4 th inductor current characteristic value is also represented, V p Representing the equivalent power supply voltage of the primary side of the transformer, and V in the primary side converter process p ＝n·V out N represents the transformation ratio of the transformer, 2Q oss (V in ) Representing the primary equivalent power V flowing into the transformer p V of the total charge amount of (2) in Representing the DAB input voltage.
Further, in S13, the secondary side conversion process time expression of the DAB transformer is:
wherein Δt is 1 Representing the secondary side commutation time, t 1 Indicating the secondary side commutation start time, t 2 Indicating the end time of secondary side commutation, L' indicating the value of inductance L equivalent to secondary side, C osss Representing the equivalent average output capacitance theta of the secondary side power device in the secondary side current conversion process s Represents the trajectory angle of the change of the secondary side current through Cheng Xiangliang according to the phase plane analysis method, wherein when V in ＝n·V out When (1):
when V is in ≠n·V out When (1):
the primary side converter process time expression of the DAB transformer in the S13 is as follows:
wherein Δt is 3 Representing the primary commutation time, t 3 Indicating the primary side commutation start time, t 4 C represents the end time of primary side converter ossp Representing the equivalent average output capacitance, theta, of a primary power device in a primary commutation process p Representing the change in the trajectory angle of the primary current Cheng Xiangliang according to phase plane analysis, where when V in ＝n·V out When (1):
when V is in ≠n·V out When (1):
further, the relation between the inductor current characteristic values in the non-commutation process in S14 is:
wherein Δt is 2 Representing inductor current from I L2 Change to I L3 Time of Deltat 4 Showing inductor current from I L4 Change to-I L1 Time, T of (1) s Representing DAB operationPeriod t d The phase shift time when DAB adopts simple phase shift control is represented.
Further, in S15, a set of inductor current characteristic values that fully satisfy all the above relationships is found out through a traversal algorithm, which specifically includes:
setting the traversal algorithm to be I additionally L1 Lower limit estimate I of (2) L1min And an inductor current characteristic value calculation error E I The method comprises the steps of carrying out a first treatment on the surface of the At the estimated value I L1 From I L1min In the gradual incremental change process, by adding I L1 Continuously substituting the calculated value-I into the corresponding relation of the inductance current characteristic values or the commutation time obtained in S11, S13 and S14 L1 ' AND-set estimate I L1 Numerical relationships between each other until a set of satisfying I is found L1 +(–I L1 ')<E I Is the inductor current characteristic value E I And representing the satisfaction degree of the corresponding relation between the solved characteristic values.
Further, the modified generalized Steinoyz equation based on current in S2 is expressed as:
wherein,indicating the magnitude of core loss per unit volume, k CB Representing a calculation constant, N L Indicating the number of turns of the inductance winding, A e The equivalent window area of the inductance magnetic core is represented, alpha, beta and k represent Steinmetz factors of magnetic core materials, the alpha value range is 0.5-3, I Lmax Represents the maximum value of the inductance current, m represents the mth accumulation operation, and delta I L Representing the variation of the characteristic value of adjacent inductances, delta I Lm ＝I Lm+1 –I Lm 。
Further, the expression of the core loss of the inductor in S2 is:
wherein P is core Representing core loss of inductance, V e Representing the equivalent volume of the inductor core.
Further, the effective value calculation formula of the inductor current in S3 is as follows:
wherein I is Lrms Representing the current effective value of the inductor;
the winding loss expression of the inductor is as follows:
wherein P is winding Representing winding loss of inductance, R w Representing the resistance of the inductive winding.
Further, the expression of the total inductance loss in S4 is:
P total ＝P core +P winding
wherein P is total Representing the total loss of the inductance;
the temperature rise expression of the inductor in operation is:
ΔT L ＝P total ·R thL
wherein DeltaT L Indicating the temperature rise of the inductor in the normal working process of DAB, R thL Representing the thermal resistance of the inductor.
Compared with the prior art, the invention has the following beneficial technical effects:
according to the invention, through DAB technical indexes and parameters of the inductance magnetic core, accurate inductance current characteristic values are obtained through calculation by using a relation among inductance current characteristic values through a traversal algorithm, and an improved generalized Steinmetz equation expression based on inductance is given out through the current characteristic values, so that an inductance magnetic core loss expression in DAB is given out. In addition, the loss expression of the inductance winding in DAB can be given through the current characteristic values, and the total loss and the temperature rise of the inductance are accurately calculated. The method solves the problems of long time consumption and complex calculation of the inductance loss calculation, provides the inductance loss calculation method with high calculation accuracy for the DAB circuit, is convenient for a designer to realize accurate estimation of the inductance temperature rise in the design process, and ensures the operation reliability of the DAB practical device.
Drawings
FIG. 1 is a typical circuit diagram of DAB;
FIG. 2 shows a primary-secondary side-by-Cheng Dengxiao resonant circuit diagram, (a) a secondary side-by-Cheng Dengxiao resonant circuit diagram, and (b) a primary side-by-Cheng Dengxiao resonant circuit diagram;
fig. 3 shows waveforms of the inductor current measured by experiment, (a) is a primary side commutation waveform, and (b) is a secondary side commutation waveform;
FIG. 4 is a graph of inductor current waveforms under calculated experimental conditions;
FIG. 5 is a graph of experimentally measured inductance temperature, (a) inductance initial temperature, (b) inductance steady state temperature;
FIG. 6 is a graph showing the comparison between the calculated value and the experimental test value of the inductance temperature rise under different conditions;
fig. 7 is a flowchart of DAB inductance loss algorithm.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that, unless explicitly stated and limited otherwise, the terms "comprises" and "comprising" indicate the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
The method comprises the following specific steps:
the method comprises the following steps of: s1, obtaining a start-end inductance current value I of DAB primary and secondary side conversion process according to DAB circuit technical indexes and selected device parameters L1 、I L2 、I L3 I L4 The relation between the inductance current values is called as the characteristic value of the inductance current; s2, according to the principle of the primary and secondary side conversion process, an equivalent resonance circuit and an equivalent resonance process of the DAB conversion process are given; s3, obtaining the primary and secondary side conversion process time delta t through a vector trajectory method according to the resonant circuit 1 And delta t 2 The method comprises the steps of carrying out a first treatment on the surface of the S4, according to DAB circuit technical indexes, the change relation between the inductance current characteristic values in the non-commutation process is given; s5, finding out a group of inductance current characteristic values which fully satisfy all the relations through a traversal algorithm.
A typical circuit diagram of DAB is shown in fig. 1. When DAB works, the upper and lower power devices of the same bridge arm have current conversion in the dynamic process. In the current conversion process, the inductance energy rises or falls due to the release or absorption of the charge of the equivalent voltage source of the primary side and the secondary side. The energy conversion is embodied as a rise or fall in inductor current. The secondary side commutation start-end inductance current relation is as follows:
wherein L represents DAB inductance value, I L1 Indicating the inductance current value at the initial moment of the secondary side conversion process, I L2 The inductance current value V at the end of the secondary side commutation process s Representing the equivalent power supply voltage of the secondary side of the transformer and V in the secondary side converter process s ＝V in N, n represents the transformer transformation ratio, 2Q oss (V out ) Representing the secondary equivalent power V of the slave transformer s Total amount of electric charge flowing out, V out Represents DAB output voltage, C oss (v) Representing the output capacitance of the power device at different voltages.
The relation between the inductance current and the inductance current at the beginning and the end of primary side converter is as follows:
wherein I is L3 Indicating the inductance current value at the initial moment of the primary side exchange process, I L4 The inductor current value V at the end of the primary side commutation process p Representing the equivalent power supply voltage of the primary side of the transformer, and V in the primary side converter process p ＝n·V out ，2Q oss (V in ) Representing the primary equivalent power V flowing into the transformer p V of the total charge amount of (2) in Representing the DAB input voltage.
In order to accurately obtain the relation between the characteristic values of the inductance currents, the conversion process time should be accurately solved. During analysis, it was found that the commutation process could be equivalent to an LC resonant circuit. Primary and secondary side converterThe process equivalent resonant circuit diagram may be plotted as shown in fig. 2. Wherein the secondary side of the converter can be equivalently an inductance L' and a capacitance C osss Wherein the capacitance voltage is v 1s (t)–v 2s (t) inductor current i L ' (t) the excitation source is V s 。v 1s (t) and v 2s The potential represented by (t) is shown in FIG. 1. V (V) s Is the absolute value of the voltage at the secondary side of the transformer. The primary side of the converter can be equivalent to an inductor L and a capacitor C ossp Wherein the capacitance voltage is v 1p (t)–v 2p (t) inductor current i L (t) the excitation source is V p 。v 1p (t) and v 2p The potential represented by (t) is shown in FIG. 1. V (V) p Is the absolute value of the primary voltage of the transformer. Based on the phase plane trajectory method, a secondary side stream change process time expression can be obtained:
wherein Δt is 1 Representing the secondary side commutation time, t 1 Indicating the secondary side commutation start time, t 2 Indicating the end time of secondary side commutation, L' indicating the value of inductance L equivalent to secondary side, C osss Representing the equivalent average output capacitance theta of the secondary side power device in the secondary side current conversion process s The trajectory angle of the secondary side current change Cheng Xiangliang obtained by phase plane analysis is shown.
However, for DAB, the inductance is equivalent to the secondary when analyzing secondary commutation. The secondary side voltage of the transformer is equivalent to V in N, however V in And n.V out Are not always equal and thus require a case-by-case discussion.
When V is in ＝n·V out When (1):
when V is in ≠n·V ou When (1):
the primary side commutation process time expression can be obtained:
wherein Δt is 3 Representing the primary commutation time, t 3 Indicating the primary side commutation start time, t 4 C represents the end time of primary side converter ossp Representing the equivalent average output capacitance, theta, of a primary power device in a primary commutation process p The change in the trajectory angle of the primary current Cheng Xiangliang according to the phase plane analysis method is shown.
When V is in ＝n·V out When (1):
when V is in ≠n·V ou When (1):
in addition, according to the connection relation between the DAB circuit working principle and the circuit, the relation between the inductance current characteristic values in the non-commutation process can be obtained as follows:
wherein Δt is 2 Representing inductor current from I L2 Change to I L3 Time of Deltat 4 Showing inductor current from I L4 Change to-I L1 Time, T of (1) s Indicating DAB working period, t d The phase shift time when DAB adopts simple phase shift control is represented.
Equations (1) - (10) can fully represent 4 inductor current characteristic values I L1 、I L2 、I L3 I L4 Relationship between them. Firstly, setting an initial value I of a traversal algorithm L1min So that the estimated value I L1 From I L1min According to the calculated error E I Gradually increasing for incremental steps and adding these estimates I L1 Substituting into formulas (1) - (10), continuously judging calculated value-I L1 ' AND-set estimate I L1 Numerical relationships between each other until a set of satisfying I is found L1 +(–I L1 ')<E I Is a characteristic value of inductor current. E (E) I The satisfaction degree of the corresponding relation among the characteristic values is comprehensively represented. And verifying the accuracy and the effectiveness of the DAB inductance current characteristic value calculation method by using a DAB device with the input and output voltages of 400V, the working frequency of 10kHz and the rated power of 1600W. Fig. 3 shows the magnitude of the characteristic value of the inductor current and the time of the current converting process, and fig. 4 shows the corresponding value obtained by solving the characteristic value of the DAB inductor current according to the invention by the accurate calculating method. It can be found that the calculation is more consistent with the measured data, and the maximum error of the calculation occurs in I L4 At this point, the error is less than 2%.
And (II) accurately calculating DAB inductance loss, comprising the following steps: s1, giving a current-based modified generalized Steinotz equation (Current Based improved Generalized Steinmetz Equation, CBiGSE) according to an inductance current characteristic value, and calculating the magnetic core loss of an inductance; s2, a calculation formula of the inductance winding loss is given according to the inductance current characteristic value; s3, an inductance total loss expression and an inductance working temperature rise expression are given.
The inductance loss in DAB includes two major parts, namely core loss and winding loss. The inductance core loss can be found from the unit core loss and the equivalent core volume, where the unit core loss is usually found from the iGSE equation, which is conventional as follows:
the following relationship exists between the inductor magnetic flux density and the inductor current:
through analysis of DAB working principle and analysis of change rule of inductance magnetic flux density, the relational expression (12) and the inductance current characteristic value are combined, so that the iGSE Chinese formula (10) can be simplified. Furthermore, equation (11) requires complex integration calculations, and the Steinmetz factor α is typically in the range of 0.5-3, which can be simplified for equation (11). In combination with the above analysis, the following modified generalized Steinotz equation based on current can be obtained:
wherein,indicating the magnitude of core loss per unit volume, k CB Representing a calculation constant, N L Indicating the number of turns of the inductance winding, A e The equivalent window area of the inductance magnetic core is represented, alpha, beta and k represent Steinmetz factors of magnetic core materials, the alpha value range is 0.5-3, I Lmax Represents the maximum value of the inductance current, m represents the mth accumulation operation, and delta I L Representing the variation of the characteristic value of adjacent inductances, delta I Lm ＝I Lm+1 –I Lm 。
The inductor core loss can therefore be found by the following expression:
wherein P is core Representing core loss of inductance, V e Representing the equivalent volume of the inductor core.
The inductance winding loss can be determined from the effective value of the current flowing through the inductor and the inductance winding resistance, wherein the effective value of the inductor current is given based on the characteristic value of the inductor current as follows:
wherein I is Lrms Representing the current effective value of the inductor.
The inductance winding loss can be calculated from the following expression:
wherein P is winding Representing winding loss of inductance, R w Representing the resistance of the inductive winding.
The total inductance loss can be found by the following expression:
P total ＝P core +P winding (19)
wherein P is total Indicating the total loss of inductance.
The inductance temperature rise can be found by the following expression:
ΔT L ＝P total ·R thL (20)
wherein DeltaT L Indicating the temperature rise of the inductor in the normal working process of DAB, R thL Representing the thermal resistance of the inductor.
And verifying the accuracy and the effectiveness of a DAB inductance loss calculation method based on the inductance current characteristic value by using a DAB device with the input and output voltages of 400V, the working frequency of 10kHz and the rated power of 1600W. Fig. 5 shows a graph of the initial temperature versus the steady-state temperature of the experimentally measured inductor at the transmission power of the DAB circuit, resulting in a steady-state DAB inductor at about 20 minutes of operation under experimental conditions with a temperature rise of 20.1 ℃. The inductance temperature rise under the experimental condition is about 20.4 ℃ by the DAB inductance loss calculation method provided by the invention, and the error between the calculated data and the experimental data is about 1.5%. FIG. 6 shows that the working frequency of the circuit is 50kHz to 150kHz, a plurality of groups of experimental data are compared with the calculated data when the input and output voltages of the circuit are 200V to 600V, the calculated data and the experimental data are well matched at each point, and the maximum error is lower than 4%.
The flow of DAB inductance loss algorithm based on the characteristic value of the inductance current is shown in figure 7. Aiming at the inductance loss and the temperature rise of the double-active bridge DAB circuit, the invention optimizes the iGSE method for calculating the magnetic core loss by calculating the inductance current characteristic value, provides a method for calculating the magnetic core loss of the iGSE based on current, and provides a winding loss expression based on current. The invention finally provides an innovative method for calculating the total loss of the DAB inductor through the characteristic value of the inductor current, solves the problems of long time consumption and complex calculation of the inductor loss calculation, simultaneously provides an inductor loss calculation method with higher calculation accuracy aiming at the DAB circuit, is convenient for a designer to realize accurate estimation of the inductor temperature rise in the design process, and ensures the reliability of the operation of a DAB practical device.
The above is only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited by this, and any modification made on the basis of the technical scheme according to the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (6)
1. The DAB inductance loss calculation method based on the inductance current characteristic value is characterized by comprising the following steps of:
s1: calculating a DAB inductance current characteristic value;
the calculating of the DAB inductor current characteristic value specifically comprises the following steps:
s11: obtaining the relation of the characteristic values of the inductor current flowing through Cheng Shimo of the primary side and the secondary side of the DAB transformer according to the technical index of the DAB circuit and the selected device parameters;
s12: according to the principle of primary and secondary side commutation process, an equivalent resonance circuit and an equivalent resonance process of the DAB commutation process are obtained;
s13: according to the equivalent resonant circuit and the corresponding equivalent resonant process, obtaining the time relation of the primary side and the secondary side of the DAB transformer in the conversion process by a vector track method;
s14: obtaining a change relation between inductance current characteristic values in a non-commutation process according to DAB circuit technical indexes;
s15: finding out a group of inductor current characteristic values which fully meet the relationship of inductor current characteristic values of the current through Cheng Shimo in S11, the time relationship of the primary side and secondary side in S13 and the relationship of the current characteristic values of the current without Cheng Diangan in S14 through a traversing algorithm;
s2: obtaining an improved generalized Steinotz equation based on current according to the characteristic value of the inductance current, and calculating the magnetic core loss of the inductance by utilizing the improved generalized Steinotz equation based on current;
wherein the modified generalized Steinmetz equation based on current is expressed as:
wherein,indicating the magnitude of core loss per unit volume, k CB Representing a calculation constant, N L Indicating the number of turns of the inductance winding, A e The equivalent window area of the inductance magnetic core is represented, alpha, beta and k represent Steinmetz factors of magnetic core materials, the alpha value range is 0.5-3, I Lmax Represents the maximum value of the inductance current, m represents the mth accumulation operation, and delta I L Representing the variation of the characteristic value of adjacent inductances, delta I Lm ＝I Lm+1 –I Lm ；
S3: obtaining an inductance current effective value calculation formula according to the inductance current characteristic value, and calculating the winding loss of the inductor according to the inductance current effective value calculation formula;
the inductance current effective value calculation formula is as follows:
wherein I is Lrms Representing the current effective value of the inductor;
the winding loss expression of the inductor is as follows:
wherein P is winding Representing winding loss of inductance, R w Representing the resistance of the inductive winding;
s4: obtaining an inductance total loss expression and a temperature rise expression of the inductance during operation according to the magnetic core loss and the winding loss in the S2 and the S3;
the expression of the total inductance loss is as follows:
P total ＝P core +P winding
wherein P is total Representing the total loss of the inductance;
the temperature rise expression of the inductor in operation is:
ΔT L ＝P total ·R thL
wherein DeltaT L Indicating the temperature rise of the inductor in the normal working process of DAB, R thL Representing the thermal resistance of the inductor.
2. The DAB inductance loss calculating method based on the characteristic value of the inductor current as claimed in claim 1, wherein the relation between the characteristic value of the inductor current flowing through Cheng Shimo of the secondary side of the DAB transformer in S11 is:
wherein L represents DAB inductance value, I L1 The induction current value at the initial moment of the secondary side exchange process is shown, and the 1 st induction current characteristic value is also shown, I L2 The inductor current value at the end of the secondary side commutation process is represented, and the 2 nd inductor current characteristic value is also represented, V s Representing the equivalent power supply voltage of the secondary side of the transformer and V in the secondary side converter process s ＝V in N, n represents the transformer transformation ratio, 2Q oss (V out ) Representing the secondary equivalent power V of the slave transformer s Total amount of electric charge flowing out, V out Represents DAB output voltage, C oss (v) Output capacitance of the power device under different voltages is represented;
the relation between the primary side commutated Cheng Shimo inductance current characteristic values of the DAB transformer in the S11 is as follows:
wherein I is L3 The inductor current value at the initial moment of the primary side exchange process is represented, and the characteristic value of the 3 rd inductor current is also represented, I L4 The inductor current value at the end of the primary side commutation process is represented, and the 4 th inductor current characteristic value is also represented, V p Representing the equivalent power supply voltage of the primary side of the transformer, and V in the primary side converter process p ＝n·V out N represents the transformation ratio of the transformer, 2Q oss (V in ) Representing the primary equivalent power V flowing into the transformer p V of the total charge amount of (2) in Representing the DAB input voltage.
3. The DAB inductance loss calculating method based on the inductance current characteristic value according to claim 1, wherein the DAB transformer secondary side commutation process time expression in S13 is:
wherein Δt is 1 Representing the secondary side commutation time, t 1 Indicating the secondary side commutation start time, t 2 Indicating the end time of secondary side commutation, L' indicating the value of inductance L equivalent to secondary side, C osss Representing the equivalent average output capacitance theta of the secondary side power device in the secondary side current conversion process s Represents the trajectory angle of the change of the secondary side current through Cheng Xiangliang according to the phase plane analysis method, wherein when V in ＝n·V out When (1):
when V is in ≠n·V out When (1):
the primary side converter process time expression of the DAB transformer in the S13 is as follows:
wherein Δt is 3 Representing the primary commutation time, t 3 Indicating the primary side commutation start time, t 4 C represents the end time of primary side converter ossp Representing the equivalent average output capacitance, theta, of a primary power device in a primary commutation process p Representing the change in the trajectory angle of the primary current Cheng Xiangliang according to phase plane analysis, where when V in ＝n·V out When (1):
when V is in ≠n·V out When (1):
4. the DAB inductance loss calculating method based on the inductance current characteristic value according to claim 1, wherein the relation between the inductance current characteristic values in the non-commutation process in S14 is:
wherein Δt is 2 Representing inductor current from I L2 Change to I L3 Time of Deltat 4 Showing inductor current from I L4 Change to-I L1 Time, T of (1) s Indicating DAB working period, t d The phase shift time when DAB adopts simple phase shift control is represented.
5. The DAB inductance loss calculation method based on the inductance current characteristic value according to claim 1, wherein the step S15 is to find a set of inductance current characteristic values that fully satisfy all the above relationships through a traversal algorithm, specifically:
setting the traversal algorithm to be I additionally L1 Lower limit estimate I of (2) L1min And an inductor current characteristic value calculation error E I The method comprises the steps of carrying out a first treatment on the surface of the At the estimated value I L1 From I L1min In the gradual incremental change process, by adding I L1 Continuously substituting the calculated value-I into the corresponding relation of the inductance current characteristic values or the commutation time obtained in S11, S13 and S14 L1 ' AND-set estimate I L1 Numerical relationships between each other until a set of satisfying I is found L1 +(–I L1 ')<E I Is the inductor current characteristic value E I And representing the satisfaction degree of the corresponding relation between the solved characteristic values.
6. The DAB inductance loss calculating method based on the inductance current characteristic value according to claim 1, wherein the expression of the core loss of the inductance in S2 is:
wherein P is core Representing core loss of inductance, V e Representing the equivalent volume of the inductor core.
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| WO2019008854A1 (en) * | 2017-07-04 | 2019-01-10 | 三菱電機株式会社 | Power conversion device |
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| WO2019008854A1 (en) * | 2017-07-04 | 2019-01-10 | 三菱電機株式会社 | Power conversion device |
| CN110768536A (en) * | 2019-10-30 | 2020-02-07 | 北京机械设备研究所 | Double-active-bridge circuit loss control method |
| CN112069655A (en) * | 2020-08-04 | 2020-12-11 | 三峡大学 | Loss calculation method for high-frequency high-power three-phase transformer |
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