Parameter design method and device of resonant converter

Abstract

The application provides a parameter design method of a resonant converter, comprising: determining a loss and magnetizing inductance curve of the resonant converter based on a zero-voltage switching requirement of a primary side switching device of the resonant converter and a zero-current switching requirement of a secondary side switching device, wherein the loss comprises a switching loss and an on-state loss; and determining a magnetizing inductance design value meeting an efficiency optimal condition based on the loss and magnetizing inductance curve of the resonant converter.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of resonant converters, in particular to a parameter design method of a resonant converter and a device thereof. BACKGROUND

[0002] The isolated DC-DC converter realizes the electrical isolation of the primary and secondary sides, has the advantages of small size, light weight, high efficiency, etc., the wide range of voltage gain and full load soft switching characteristics of the resonant (LLC) high-frequency DC-DC converter are more prominent in high-voltage and high-power applications, and are widely used in rail transit traction power electronic transformers, multi-port DC-DC direct current power distribution networks, new energy vehicles and other fields, and have become a research hotspot for domestic and foreign experts and scholars.

[0003] In recent years, with the rapid development of high-frequency power electronic technology, isolated resonant converters taking power semiconductor devices as the core have been widely applied. Considering the requirements of weight and size of high-power converters, increasing the switching frequency of the converter becomes an effective means; but higher switching frequency will inevitably result in greater switching loss, which brings great challenges to the design and heat dissipation of the converter, and the size and weight of the system are also limited. As a kind of resonant converter, LLC resonant converter can realize zero-voltage turn-on (ZVS) of the primary power tube and zero-current turn-off (ZCS) of the secondary diode compared with traditional hard switching, thereby greatly reducing the loss of the converter and achieving the purpose of weight and size reduction. Compared with other soft switching technologies, LLC resonant converter does not require additional hardware circuit, the voltage borne by the power device is only the bus voltage, and the output filter design is simple, which has the advantages of simple structure and high reliability, and has great application prospect in direct-direct conversion occasions.

[0004] The topology structure of the LLC resonant converter is shown in Figure 1 , wherein V in is the input voltage, C1 and C2 are the support capacitors of the upper half voltage and the lower half voltage respectively, S1-S8 are the switching tubes of the full-bridge three-level primary side, D 11 -D 14 are clamping diodes; L m , L r , C r are the excitation inductance, resonant inductance and resonant capacitance of the resonant cavity respectively, i Lr is the resonant current, i Lm is the excitation current, i sec ' is the current of the secondary side current converted to the primary side, i sec is the secondary side current; n is the transformation ratio of the high-frequency transformer, V1-V4 are the secondary side switching tubes, C d is the output support capacitor, and R Lis the load, V0 is the output voltage. Through reasonable design of LLC resonant cavity parameters, the output voltage can be adjusted in a wide range, the primary side switching device realizes ZVS, and the secondary side switching device realizes ZCS, therefore, the design of LLC resonant parameters is related to the performance of the converter.

[0005] Traditional design idea of LLC resonant converter: the traditional design idea of LLC resonant converter first determines the transformation ratio of the high-frequency transformer under the rated working condition of the converter according to the performance index of the converter; secondly, the gain range of the converter is determined through calculation, and the frequency range of the output voltage is further determined; thirdly, the Q value of the converter is reasonably selected under the condition of ensuring soft switching implementation; after the above steps are completed, the design of the resonant cavity parameters can be completed.

[0006] The main deficiencies of the traditional LLC resonant cavity parameter design are as follows:

[0007] 1. The traditional LLC resonant cavity parameter design is based on the gain of the converter, and the high-power LLC converter basically works in constant DC gain ratio. The constant DC gain ratio indicates that the converter works at a constant frequency, and it is not desirable to have a wide frequency range, and a wide frequency range will also bring a burden to the design of the high-frequency transformer.

[0008] 2. The traditional LLC resonant cavity parameter design can complete the charge transfer of the junction capacitor in the dead time to realize ZVS, without considering the influence of the dead time. In small power occasions, the proportion of the dead time is small and can be ignored, while in high-power occasions, the large dead time will cause the resonant current to reverse zero and cannot realize ZVS.

[0009] 3. The traditional LLC resonant cavity parameter design cannot guarantee the optimal efficiency of the converter. Generally, according to engineering experience, the larger the excitation inductance, the higher the efficiency, but in fact, the efficiency and the excitation inductance are not a simple linear relationship. In the whole parameter design process, the selection of the excitation inductance depends on the inductance ratio k, and the inductance ratio that meets the gain requirement has no solution, so the excitation inductance also has no solution, and the efficiency of the converter selected under the excitation inductance is not necessarily optimal.

[0010] 4. The traditional LLC resonant cavity parameter design does not consider the engineering constraint condition. The larger the excitation inductance, the smaller the off-current, and considering the off-delay of the switching tube (the smaller the off-current, the longer the off-time), if the off is not completely in the dead time, at this time, the other switching tube of the same bridge arm will necessarily have a reverse impact current, which threatens the safe operation of the converter.

[0011] Therefore, in order to solve the above problems, the present application aims to provide a resonant cavity converter design method, which can realize the optimal design of the efficiency of the converter. SUMMARY

[0012] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0013] According to an aspect of the present application, there is provided a parameter design method of a resonant converter, comprising: determining a relationship curve of loss and magnetizing inductance of the resonant converter based on a zero-voltage switching requirement of a primary side switching device and a zero-current switching requirement of a secondary side switching device of the resonant converter, the loss including switching loss and on-state loss; and determining a magnetizing inductance design value satisfying an efficiency optimal condition based on the relationship curve of loss and magnetizing inductance of the resonant converter.

[0014] Further, the determining of the magnetizing inductance value satisfying the efficiency optimal condition of the resonant converter based on the relationship curve of loss and magnetizing inductance of the resonant converter comprises: determining a magnetizing inductance value corresponding to a lowest loss point as a magnetizing inductance theoretical value satisfying the efficiency optimal condition based on the relationship curve of loss and magnetizing inductance of the resonant converter; determining a magnetizing inductance critical value satisfying a constraint condition of an engineering off-current based on the constraint condition; and determining the magnetizing inductance design value based on the magnetizing inductance theoretical value and the magnetizing inductance critical value.

[0015] Further, the determining of the magnetizing inductance design value based on the magnetizing inductance theoretical value and the magnetizing inductance critical value comprises: determining the magnetizing inductance theoretical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being less than or equal to the magnetizing inductance critical value; and determining the magnetizing inductance critical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being greater than the magnetizing inductance critical value.

[0016] Further, the determining of the relationship curve of loss and magnetizing inductance of the resonant converter based on a zero-voltage switching requirement of a primary side switching device and a zero-current switching requirement of a secondary side switching device of the resonant converter comprises: determining a turns ratio of a high frequency transformer in the resonant converter based on a performance index requirement of the resonant converter; determining a resonant frequency of the resonant converter based on a power level of the resonant converter and a model of a switching device; and substituting the turns ratio, the resonant frequency and other constant parameters into a relationship formula of loss and magnetizing inductance of the resonant converter to determine the relationship curve of loss and magnetizing inductance.

[0017] Further, the parameter design method further comprises: establishing a relationship between the loss of the resonant converter and the magnetizing inductance.

[0018] Further, the establishing the relationship between the loss of the resonant converter and the magnetizing inductance comprises: determining a relationship between the effective value of the resonant current and the magnetizing inductance based on the requirement of zero voltage switching of the magnetizing inductance and the relationship among the resonant period, the switching period and the dead time, the relationship involving the influence of the dead time on the magnetizing inductance; determining a relationship between the effective value of the secondary side current and the magnetizing inductance based on the relationship among the resonant current, the magnetizing current and the load current; determining the turn-on loss and the turn-off loss of the primary side switching device and the turn-on loss and the turn-off loss of the secondary side switching device based on the requirement of zero voltage switching of the primary side switching device, the requirement of zero current switching of the secondary side switching device, the relationship between the effective value of the resonant current and the magnetizing inductance and the relationship between the effective value of the secondary side current and the magnetizing inductance; and summing up the turn-on loss and the turn-off loss of the primary side switching device and the turn-on loss and the turn-off loss of the secondary side switching device to obtain the relationship between the loss of the resonant converter and the magnetizing inductance.

[0019] Further, the determining the turns ratio of the high frequency transformer in the resonant converter based on the performance index requirement of the resonant converter comprises: determining the turns ratio by using the input rated voltage and the output rated voltage of the resonant converter.

[0020] Further, the parameter design method further comprises: determining the inductance ratio design value of the resonant converter by using a step-by-step approximation method; determining the resonant inductance design value of the resonant converter based on the inductance ratio design value and the magnetizing inductance design value; and determining the resonant capacitance design value of the resonant converter based on the resonant inductance design value and the resonant frequency.

[0021] Further, the determining the inductance ratio design value of the resonant converter by using a step-by-step approximation method comprises: assuming the inductance ratio value of the resonant converter; drawing a gain curve corresponding to the assumed inductance ratio value by using FHA analysis method to determine whether the gain meets the performance index requirement of the resonant converter; and determining the maximum value of the inductance ratio value meeting the performance index requirement of the resonant converter as the inductance ratio design value.

[0022] Further, the determining the resonant inductance of the resonant converter based on the inductance ratio design value and the magnetizing inductance design value comprises: calculating the resonant inductance design value by using a resonant inductance calculation formula L r = L m / k, wherein L r is the resonant inductance design value, L m is the magnetizing inductance design value, and k is the inductance ratio design value.

[0023] Further, the determining the resonant capacitance design value of the resonant converter based on the resonant inductance and the resonant frequency comprises: using a resonant capacitance calculation formula calculating the resonant capacitance design value, wherein L r is the resonant inductance design value, f r is the resonant frequency.

[0024] According to another aspect of the present application, there is also provided a parameter design device of a resonant converter, comprising: a memory; and a processor coupled with the memory, the processor being configured to: determine a loss-magnetizing inductance curve of the resonant converter based on a zero-voltage switching requirement of a primary side switching device and a zero-current switching requirement of a secondary side switching device of the resonant converter, the loss comprising a switching loss and an on-state loss; and determine a magnetizing inductance design value satisfying an efficiency optimal condition based on the loss-magnetizing inductance curve of the resonant converter.

[0025] Further, the processor is further configured to: determine a magnetizing inductance value corresponding to a loss minimum point as the magnetizing inductance theoretical value satisfying the efficiency optimal condition based on the loss-magnetizing inductance curve of the resonant converter; determine a magnetizing inductance critical value satisfying a constraint condition of an engineering off current based on the constraint condition; and determine the magnetizing inductance design value based on the magnetizing inductance theoretical value and the magnetizing inductance critical value.

[0026] Further, the processor is further configured to: determine the magnetizing inductance theoretical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being less than the magnetizing inductance critical value; and determine the magnetizing inductance critical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being greater than the magnetizing inductance critical value.

[0027] Further, the processor is further configured to: determine a turns ratio of a high frequency transformer in the resonant converter based on a performance index requirement of the resonant converter; determine a resonant frequency of the resonant converter based on a power level of the resonant converter and a model of a switching device; and substitute the turns ratio, the resonant frequency and other constant parameters into a loss-magnetizing inductance formula of the resonant converter to determine the loss-magnetizing inductance curve.

[0028] Further, the processor is further configured to: establish the loss-magnetizing inductance formula of the resonant converter.

[0029] Further, the processor is further configured to: determine a relationship between a root mean square of the resonant current and the magnetizing inductance based on a zero voltage switching requirement of the primary side switching device and a relationship among the resonant period, the switching period and the dead time, the relationship involving an effect of the dead time on the magnetizing inductance; determine a relationship between a root mean square of the secondary side current and the magnetizing inductance based on a relationship among the resonant current, the magnetizing current and the load current; determine turn-on loss and turn-off loss of the primary side switching device and turn-on loss and turn-off loss of the secondary side switching device based on the zero voltage switching requirement of the primary side switching device, a zero current switching requirement of the secondary side switching device, the relationship between the root mean square of the resonant current and the magnetizing inductance, and the relationship between the root mean square of the secondary side current and the magnetizing inductance; and sum the turn-on loss and the turn-off loss of the primary side switching device and the turn-on loss and the turn-off loss of the secondary side switching device to obtain a relationship between the loss of the resonant converter and the magnetizing inductance.

[0030] Further, the processor is further configured to determine the turns ratio using an input rated voltage and an output rated voltage of the resonant converter.

[0031] Further, the processor is further configured to: determine a design value of the inductance ratio using the step-by-step approximation method; determine a design value of the resonant inductance of the resonant converter based on the design value of the inductance ratio and the design value of the magnetizing inductance; and determine a design value of the resonant capacitance of the resonant converter based on the design value of the resonant inductance and the resonant frequency.

[0032] Further, the processor is further configured to: assume a value of the inductance ratio of the resonant converter; plot a gain curve corresponding to the assumed value of the inductance ratio using the FHA analysis method to determine whether the gain meets a performance index requirement of the resonant converter; and determine a maximum value of the inductance ratio that meets the performance index requirement of the resonant converter as a set value of the inductance ratio.

[0033] Further, the processor is further configured to: calculate the design value of the resonant inductance using a resonant inductance calculation formula L r = L m / k, where L r is the design value of the resonant inductance, L m is the design value of the magnetizing inductance, and k is the design value of the inductance ratio.

[0034] Further, the processor is further configured to: calculate the design value of the resonant capacitance using a resonant capacitance calculation formula , where L r is the design value of the resonant inductance, and f r is the resonant frequency.

[0035] According to still another aspect of the present application, there is also provided a computer storage medium having stored thereon a computer program which, when executed by a computer, implements the steps of the parameter design method of the resonant converter according to any one of the above aspects.

[0036] The resonant converter designed according to the parameter design method of the resonant converter of the present application can keep high efficiency operation, reduces the difficulty of cooling design of the resonant converter, and is beneficial to reduce the volume and weight of the converter and improve the power density of the converter.

[0037] The parameter design method of the resonant converter of the present application further selects the excitation inductance by reasonably selecting the off current from the perspective of the turn-on and turn-off characteristics of the power semiconductor device, so as to ensure that the power switch tube operates in the safe region, and further ensures the safe operation of the resonant converter.

[0038] The parameter design method of the resonant converter of the present application does not need to repeatedly iterate the design of the excitation inductance, and the solving process is simple.

[0039] The parameter design method of the resonant converter of the present application has simple principle and is easy to realize in engineering. BRIEF DESCRIPTION OF DRAWINGS

[0040] The above features and advantages of the present application can be better understood after reading the detailed description of embodiments of the present application in conjunction with the following drawings.

[0041] Figure 1 is a schematic diagram of a conventional full-bridge three-level resonant converter topology according to the prior art;

[0042] Figure 2 is a schematic diagram of the parameter design method in an embodiment according to an aspect of the present application;

[0043] Figure 3A is a schematic diagram of the equivalent topology according to the equivalent topology of the resonant converter;

[0044] Figure 3B is a schematic diagram of the equivalent topology according to the equivalent topology of the resonant converter; Figure 3A is a schematic diagram of the current waveform according to the equivalent topology of the resonant converter shown in FIG. 8;

[0045] Figure 4 is a schematic diagram of part of the parameter design method in an embodiment according to an aspect of the present application;

[0046] Figure 5A is a schematic diagram of the relationship between the effective value of the resonant current and the excitation inductance in a specific embodiment according to an aspect of the present application;

[0047] Figure 5B is a schematic diagram of the relationship between the effective value of the secondary current and the magnetizing inductance in a specific embodiment according to an aspect of the present application;

[0048] Figure 6 is a schematic diagram of part of the flow of a parameter design method in an embodiment according to an aspect of the present application;

[0049] Figure 7 is a schematic diagram of the relationship between the losses of the resonant converter and the magnetizing inductance in a specific embodiment according to an aspect of the present application;

[0050] Figure 8 is a schematic diagram of part of the flow of a parameter design method in an embodiment according to an aspect of the present application;

[0051] Figure 9 is a schematic diagram of part of the flow of a parameter design method in an embodiment according to an aspect of the present application;

[0052] Figure 10 is a schematic diagram of part of the flow of a parameter design method in an embodiment according to an aspect of the present application;

[0053] Figure 11 is a schematic diagram of part of the flow of a parameter design method in an embodiment according to an aspect of the present application; DETAILED DESCRIPTION

[0054] The following description is presented to enable any person skilled in the art to practice the application and is provided in the context of a particular application and its requirements. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments. Thus, the present application is not intended to be limited to the embodiments presented, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0055] In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without necessarily being limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present application.

[0056] Readers should note all documents and references submitted concurrently with this specification and open to public inspection, the contents of which are incorporated herein by reference. Unless otherwise expressly stated, all features disclosed in this specification (including any appended claims, abstracts, and drawings) may be replaced by alternative features for the same, equivalent, or similar purposes. Therefore, unless explicitly stated otherwise, each disclosed feature is merely one example of a set of equivalent or similar features.

[0057] Note that, where used, the markings left, right, front, back, top, bottom, front, back, clockwise, and counterclockwise are merely for convenience and do not imply any specific fixed direction. In fact, they are used to reflect the relative position and / or orientation between different parts of an object. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] Note that, in practice, "further," "preferably," "even further," and "more preferably" are simply starting points for describing another embodiment based on the foregoing embodiments. The combination of the content following "further," "preferably," "even further," or "more preferably" with the foregoing embodiments constitutes the complete configuration of another embodiment. Any combination of several "further," "preferably," "even further," or "more preferably" settings following the same embodiment can form yet another embodiment.

[0060] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0061] According to one aspect of the present invention, a parameter design method for a resonant converter is provided, which is applicable to fields such as rail transit traction power electronic transformers, multi-port DC-DC power distribution networks, and new energy vehicles.

[0062] In one embodiment, such as Figure 2 As shown, the parameter design method 200 for the resonant converter includes steps S210 to S220.

[0063] The step S210 is to determine a loss versus magnetizing inductance curve of the resonant converter based on zero voltage switching (ZVS) requirement of the primary side switching device and zero current switching (ZCS) requirement of the secondary side switching device, wherein the loss includes switching loss and on-state loss.

[0064] The equivalent topology of the resonant converter is shown in Figure 3A , and the corresponding current waveform is shown in Figure 3B , wherein i Lr is the resonant current, V in is the input voltage, L r is the resonant inductance, C r is the resonant capacitance, L m is the magnetizing inductance, I Lm is the magnetizing current, I sec ' is the effective value of the primary side current, and R ac is the equivalent load resistance. Those skilled in the art can understand that the equivalent topology shown in Figure 3A is applicable to resonant converters of various topologies such as half-bridge, full-bridge, two-level, three-level or multi-level, etc. The switching tube power devices used therein can be IGBT, MOSFET, SiC or other existing or future semiconductor devices.

[0065] Specifically, a loss versus magnetizing inductance relationship of the resonant converter can be established based on the zero voltage switching requirement of the primary side switching device and the zero current switching requirement of the secondary side switching device.

[0066] The step of establishing the loss versus magnetizing inductance relationship of the resonant converter can include steps S410-S440 as shown in Figure 4 .

[0067] The step S410 is to determine a relationship between the effective value of the resonant current and the magnetizing inductance based on the magnetizing inductance achieving the zero voltage switching requirement and the relationship among the resonant period, the switching period and the dead time.

[0068] Based on Figure 3A and 3B , it can be obtained that when the switching frequency f sw of the resonant converter is equal to the resonant frequency f r , the expressions of the resonant current and the magnetizing current are as follows, respectively:

[0069]

[0070]

[0071] wherein Ipri is the effective value of the resonant current, w r is the resonant angular frequency and ω r = 2πf r , θ is the initial phase angle, V0 is the voltage across the load, n is the turns ratio, and T r is the resonant period.

[0072] In half of the switching period, the average value of the output current satisfies the following formula:

[0073]

[0074] where T s is the switching period.

[0075] Taking into account the effect of the dead time, the resonant period, the switching period and the dead time are related as follows:

[0076] T s = T r + 2T d (4)

[0077] where T d is the dead time.

[0078] To ensure that the primary side switching device of the resonant converter achieves zero voltage switching requirements, the charge transfer on the junction capacitance needs to be completed within the dead time, so the critical condition for the excitation inductance to achieve ZVS is:

[0079]

[0080] where C j is the junction capacitance, and ξ is the coefficient.

[0081] By combining equations (1) to (5), the relationship between the effective value of the resonant current and the excitation inductance is as follows:

[0082]

[0083] Further, step S420 is: determining the relationship between the effective value of the secondary side current and the excitation inductance based on the relationship between the resonant current, the excitation current and the load current.

[0084] In particular, the resonant current, the excitation current and the load current satisfy the following formula:

[0085] i sec '(t) = i Lr (t) - i Lm (t) (7)

[0086] Thus, the effective value i sec ' of the secondary side current reduced to the primary side current is:

[0087]

[0088] The relationship between the effective value of the primary side current and the excitation inductance is as follows:

[0089]

[0090] The relationship between the effective value of the secondary side current and the excitation inductance is as follows:

[0091] I sec =nI sec ' (10)

[0092] Substitute formula (9) into formula (10), and draw a curve diagram of formula (6) and formula (10). Figure 5A and 5B A curve diagram of formula (6) and formula (10) in a specific embodiment is shown. As can be seen from the specific embodiment, the relationship between the effective value of the resonance current and the excitation inductance and the relationship between the effective value of the secondary side current and the excitation inductance are not linearly changed, and there is an excitation inductance value that makes the corresponding effective value of the resonance current and the effective value of the secondary side current minimum.

[0093] Further, step S430 is to determine the turn-on loss and turn-off loss of the primary side switching device and the turn-on loss and turn-off loss of the secondary side switching device based on the zero voltage switching requirement of the primary side switching device, the zero current switching requirement of the secondary side switching device, the relationship between the effective value of the resonance current and the excitation inductance, and the relationship between the effective value of the secondary side current and the excitation inductance.

[0094] Those skilled in the art can understand that the loss of the resonant converter is divided into switching loss and on-state loss.

[0095] Since the primary side power device needs to achieve ZVS, the turn-on loss is 0, so the switching loss of the primary side power device is mainly concentrated on the turn-off loss. The on-state loss of the primary side power device includes the on-state loss of the switching tube and the on-state loss of the diode. Among them, the on-state loss of the diode accounts for a very small proportion and can be approximately ignored, so the on-state loss of the primary side power device can only consider the on-state loss of the switching tube.

[0096] For the secondary side diode, the secondary side diode is in ZCS, has no switching loss, and only has on-state loss.

[0097] The switching loss of the resonant converter, the on-state loss of the primary side switching tube, and the on-state loss of the secondary side diode are calculated respectively.

[0098] The switching loss of the resonant converter is as follows:

[0099]

[0100] wherein, is the turn-off current, f sw is the switching frequency, E on is the energy required for one turn-on (take 0), E off is the turn-off energy (consult the switch device manual), I nom is the rated current of the switch device, U nom is the rated voltage of the switch device, U dc is the voltage between the collector and the emitter (CE) of the switch device when it is turned off.

[0101] The on-state loss of the primary side switch tube is as follows:

[0102] P ss_igbt =(V F0_125 ·I pri +R D0_125 ·I pri 2 )·D1 (12)

[0103] wherein, V F0_125 is the on-state voltage drop of the primary side switch tube, R D0_125 is the equivalent resistance of the module lead, and D1 is the proportion of the on-state time.

[0104] The on-state loss of the secondary side diode is as follows:

[0105] P ss_diode =(V F ·I sec )·D2 (13)

[0106] wherein, V F is the on-state voltage drop of the secondary side diode, and D2 is the proportion of the on-state time of the secondary side diode.

[0107] Further, step S440 is to obtain the sum of the turn-on loss and the turn-off loss of the primary side switch device and the secondary side switch device as the loss of the resonant converter and the relationship with the magnetizing inductance.

[0108] The total loss of the resonant converter is as follows:

[0109] P total_loss =8·P sw_igbt +8·P ss_igbt +4·P ss_diode (14)

[0110] Then, the above formula (6), (10), (11), (12) and (13) are substituted into formula (14) to obtain the relationship between the loss of the resonant converter and the magnetizing inductance as follows:

[0111]

[0112] The skilled in the art can understand that, among the parameters involved in formula (15), the transformation ratio n and the resonance frequency f r The switching frequency f sw is equal to the resonance frequency f r . Except for the excitation inductance L m , other parameters are constant parameters.

[0113] The above derivation and calculation process does not need to be repeated in each design process, so the excitation inductance can be directly determined by using the above formula (15). As shown in Figure 6 , step S210 can include steps S211-S213.

[0114] Among them, step S211 is: determining the transformation ratio of the high-frequency transformer in the resonant converter based on the performance index requirements of the resonant converter.

[0115] The performance index requirements of the resonant converter include the output rated voltage V 0N and the rated load R L . The transformation ratio n of the high-frequency transformer is determined according to the input rated voltage and the output rated voltage, as shown in the following formula:

[0116] n = V inN / V 0N (16)

[0117] Among them, V inN is the input rated voltage, and V 0N is the output rated voltage.

[0118] Step S212 is: determining the resonance frequency of the resonant converter based on the power level of the resonant converter and the type of switching device.

[0119] According to the power level of the converter and the type of switching device, the resonance frequency f r of the converter is preliminarily determined, and the switching frequency range of the converter is f sw =(0.7-0.9)f r , the switching frequency f sw is equal to the resonance frequency f r .

[0120] Further, step S213 is: substituting the transformation ratio, the resonance frequency and other constant parameters into the relationship between the loss of the resonant converter and the excitation inductance to determine the relationship curve between the loss and the excitation inductance.

[0121] The turns ratio n and resonant frequency f are determined based on the performance requirements, power rating, and switching device models of the resonant converter. r Substitute other constant parameters into equation (15) and plot them to obtain the relationship curve between loss and excitation inductance. Figure 7 The relationship curve between loss and magnetizing inductance in a specific embodiment is shown, such as... Figure 7 As shown in the figure, based on this relationship curve, the excitation inductance value L corresponding to the minimum loss can be determined. m_cal .

[0122] Step S220 is: Based on the relationship curve between the loss of the resonant converter and the magnetizing inductance, determine the design value of the magnetizing inductance that satisfies the optimal efficiency condition.

[0123] like Figure 7 As shown, the excitation inductance value L corresponding to the minimum loss is determined based on the relationship curve between the resonant inductance and the magnetizing inductance. m_cal The theoretical value of the excitation inductance is required to meet the optimal efficiency condition of the resonant converter. However, the design value of the excitation inductance needs to meet engineering requirements. Therefore, the theoretical value of the excitation inductance can only be used when it meets the engineering requirements.

[0124] Furthermore, such as Figure 8 As shown, step S220 may include steps S221 to S223.

[0125] Step S221 involves determining the excitation inductance value corresponding to the lowest point of loss based on the relationship curve between loss and excitation inductance, so as to use it as the theoretical value of excitation inductance that satisfies the optimal efficiency condition.

[0126] Step S222 is: determining the critical value of the excitation inductance that satisfies the constraints based on the engineering turn-off current constraints.

[0127] Those skilled in the art will understand that the theoretical value of the magnetizing inductance is not necessarily feasible in engineering. If the magnetizing inductance L... m_cal Excessive parameters will increase the turn-off delay of the switching transistors, resulting in current spikes when the other switching transistor in the same bridge arm turns on, seriously threatening the reliable operation of the converter. Therefore, the constraints for the engineering-graded turn-off current are established as follows:

[0128]

[0129] Based on equation (17), the critical value L of the excitation inductance that satisfies the constraint condition of the engineering turn-off current can be obtained. m_tem As shown in equation (18):

[0130]

[0131] Among them, I off_temThe critical value of the turn-off current of the switch tube.

[0132] Further, step S223 is: determining the excitation inductance design value based on the excitation inductance theoretical value and the excitation inductance critical value.

[0133] Specifically, when the excitation inductance theoretical value L m_cal satisfies the constraint condition of the engineering turn-off current, i.e., in response to the excitation inductance theoretical value L m_cal being less than or equal to the excitation inductance critical value I off_tem , the excitation inductance theoretical value L m_cal is determined as the excitation inductance design value I m_opt .

[0134] When the excitation inductance theoretical value L m_cal does not satisfy the constraint condition of the engineering turn-off current, i.e., in response to the excitation inductance theoretical value L m_cal being greater than the excitation inductance critical value I off_tem , the excitation inductance critical value I off_tem is determined as the excitation inductance design value I m_opt .

[0135] The above is the design process of the excitation inductance parameter of the resonant converter, and the design parameters of the resonant converter also include the inductance ratio, the resonant inductance, and the resonant capacitance.

[0136] Further, the parameter design method 200 of the resonant converter can further include steps S230-S250, as shown in Figure 9 .

[0137] Among them, step S230 is: determining the inductance ratio design value of the resonant converter by using the step-by-step approximation method.

[0138] The step-by-step approximation method refers to starting from some easy-to-start conditions or some weakened conditions that are essentially related to the essential content of the problem, and then gradually expanding (or reducing) the range, gradually approaching, and finally reaching the solution required by the problem. The specific steps can be as shown in Figure 10 , including steps S231-S233.

[0139] Step S231 is: assuming the inductance ratio value of the resonant converter.

[0140] Step S232 is: using the FHA analysis method (Fundamental harmonic Approximation, basic harmonic equivalent analysis method) to draw the gain curve corresponding to the assumed inductance ratio value to determine whether the gain meets the performance index requirements of the resonant converter.

[0141] The gain of the resonant converter can be expressed by the following formula:

[0142]

[0143] wherein, f sw is the switching frequency of the resonant converter, f r is the resonant frequency, L r is the resonant inductance, C r is the resonant capacitance and R ac is the equivalent load resistance, k is the assumed inductance ratio.

[0144] It can be understood that, according to the gain curve, when the switching frequency f sw changes within the design range, if the assumed inductance ratio makes the output voltage meet the design requirements, it is considered that the gain meets the performance index requirements of the resonant converter, otherwise step S231 is continuously executed until the inductance ratio that makes the gain meet the performance index requirements of the resonant converter appears.

[0145] Step S233 is to determine the maximum value in the inductance ratio that meets the performance index requirements of the resonant converter as the inductance ratio setting value.

[0146] Those skilled in the art can understand that the above step S231 can assume inductance ratios from large to small, step S232 can determine whether the gain meets the performance index requirements of the resonant converter for each assumed inductance ratio until the inductance ratio that makes the gain meet the performance index requirements of the resonant converter appears, and step S233 determines the inductance ratio that makes the gain meet the performance index requirements of the resonant converter as the inductance ratio setting value.

[0147] Alternatively, the above step S231 can assume a certain number of inductance ratios, step S232 can determine whether the gain meets the performance index requirements of the resonant converter for each assumed inductance ratio, thereby determining the inductance ratio that makes the gain meet the performance index requirements of the resonant converter from the assumed inductance ratios, and step S233 determines a maximum value from the inductance ratios that make the gain meet the performance index requirements of the resonant converter as the inductance ratio setting value.

[0148] It can be understood that the above two methods can determine a larger inductance ratio that meets the performance index requirements of the resonant converter.

[0149] Step S240 is to determine the resonant inductance design value of the resonant converter based on the inductance ratio design value and the excitation inductance design value.

[0150] Specifically, the resonant inductance design value is calculated by using a resonant inductance calculation formula, and the resonant inductance calculation formula is as follows:

[0151] Lr = L m / k (20)

[0152] wherein L r is the resonant inductance design value, L m is the excitation inductance design value, and k is the inductance ratio design value.

[0153] Step S250 is to determine the resonant capacitance design value of the resonant converter based on the resonant inductance design value and the resonant frequency.

[0154] Specifically, the resonant capacitance design value is calculated by using a resonant capacitance calculation formula, which is as follows:

[0155]

[0156] wherein L r is the resonant inductance design value, and f r is the resonant frequency.

[0157] Although the above methods are illustrated and described as a series of acts, it is to be understood and appreciated that the methods are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and / or concurrently with other acts from that illustrated and described herein or in accordance with other acts not specifically illustrated and described herein but which could be appreciated by one skilled in the art.

[0158] According to another aspect of the present application, there is also provided a parameter design device of a resonant converter.

[0159] In one embodiment, as shown in FIG. 11, the parameter design device 1100 of the resonant converter comprises a memory 1110 and a processor 1120. Figure 11 The memory 1110 is used to store a computer program.

[0160] The processor 1120 is coupled to the memory 1110 and is used to execute the computer program stored in the memory 1110. When the processor 1120 executes the computer program stored in the memory 1110, the steps of the parameter design method 200 in any of the above embodiments are implemented.

[0161] According to still another aspect of the present application, there is also provided a computer storage medium having a computer program stored thereon, which, when executed, implements the steps of the parameter design method 200 in any of the above embodiments.

[0162]

[0163] ​Those skilled in the art will appreciate that information, signals, and data can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0164] Those skilled in the art will further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

[0165] The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein can be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0166] The steps of a method or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In the alternative, the processor and the storage medium can reside as discrete components in a user terminal.

[0167] In one or more exemplary embodiments, the functions described can be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0168] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. However, it is to be understood that the scope of the protection is defined by the appended claims and that equivalents are intended to be covered thereby. Various modifications and changes can be made as would be obvious to a person skilled in the art having the benefit of this disclosure, and it is intended to embrace all such modifications and changes as fall within the scope of the appended claims.

Claims

1. A parameter design method of a resonant converter, comprising: determining a loss versus magnetizing inductance curve of the resonant converter based on zero voltage switching requirement of a primary side switching device and zero current switching requirement of a secondary side switching device of the resonant converter, the loss comprising switching loss and on-state loss; determining a magnetizing inductance value corresponding to a loss minimum point as a magnetizing inductance theoretical value satisfying an efficiency optimal condition based on the loss versus magnetizing inductance curve of the resonant converter; determining a magnetizing inductance critical value satisfying a constraint condition of an engineering off current based on the constraint condition; and determining a magnetizing inductance design value based on the magnetizing inductance theoretical value and the magnetizing inductance critical value. The determining of the magnetizing inductance design value based on the magnetizing inductance theoretical value and the magnetizing inductance critical value comprises:

2. The parametric design method of claim 1, wherein, determining the magnetizing inductance theoretical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being less than or equal to the magnetizing inductance critical value; and determining the magnetizing inductance critical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being greater than the magnetizing inductance critical value. The determining of the loss versus magnetizing inductance curve of the resonant converter based on zero voltage switching requirement of a primary side switching device and zero current switching requirement of a secondary side switching device of the resonant converter comprises:

3. The parametric design method of claim 1, wherein, determining a turns ratio of a high frequency transformer in the resonant converter based on performance index requirement of the resonant converter; determining a resonant frequency of the resonant converter based on power level and model of switching device of the resonant converter; and substituting the turns ratio, the resonant frequency and other constant parameters into a loss versus magnetizing inductance formula of the resonant converter to determine the loss versus magnetizing inductance curve. Further comprising:

4. The parametric design method of claim 3, wherein, establishing the loss versus magnetizing inductance formula of the resonant converter. The establishing of the loss versus magnetizing inductance formula of the resonant converter comprises:

5. The parametric design method of claim 4, wherein, determining a relationship formula of effective value of resonant current versus magnetizing inductance based on magnetizing inductance achieving zero voltage switching requirement and utilizing relationship of resonant period, switching period and dead time, the relationship formula involving influence of the dead time on the magnetizing inductance; determining a relationship formula of effective value of secondary side current versus magnetizing inductance based on relationship of resonant current, magnetizing current and load current; determining turn-on loss and turn-off loss of the primary side switching device and turn-on loss and turn-off loss of the secondary side switching device based on zero voltage switching requirement of the primary side switching device, zero current switching requirement of the secondary side switching device, the relationship formula of effective value of the resonant current versus magnetizing inductance and the relationship formula of effective value of the secondary side current versus magnetizing inductance; and determining the loss versus magnetizing inductance formula of the resonant converter by summing up the turn-on loss and the turn-off loss of the primary side switching device and the secondary side switching device. The determining of the turns ratio of the high frequency transformer in the resonant converter based on performance index requirement of the resonant converter comprises:

6. The parametric design method of claim 3, wherein, determining the turns ratio by utilizing input rated voltage and output rated voltage of the resonant converter. Further comprising:

7. The parametric design method of claim 3, wherein, determining an inductance ratio design value of the resonant converter by using a step-by-step approximation method; ​ determining a resonant inductance design value of the resonant converter based on the inductance ratio design value and the magnetizing inductance design value; and determining a resonant capacitance design value of the resonant converter based on the resonant inductance design value and the resonant frequency.

8. The parametric design method of claim 7, wherein, The determining the inductance ratio design value of the resonant converter by using the step-by-step approximation method comprises: assuming an inductance ratio value of the resonant converter; drawing a gain curve corresponding to the assumed inductance ratio value by using the FHA analysis method to determine whether the gain meets the performance index requirement of the resonant converter; and determining the maximum value of the inductance ratio value meeting the performance index requirement of the resonant converter as the inductance ratio design value.

9. The parametric design method of claim 7, wherein, The determining the resonant inductance of the resonant converter based on the inductance ratio design value and the magnetizing inductance design value comprises: The resonance inductance is calculated using the formula L r = L m / k, where L r is the resonance inductance design value, L m is the field inductance design value, and k is the inductance ratio design value.

10. The parametric design method of claim 7, wherein, The determining the resonant capacitance design value of the resonant converter based on the resonant inductance and the resonant frequency comprises: Using the resonant capacitor calculation formula calculating the resonant capacitor design value, wherein L r is the resonant inductance design value, f r is the resonant frequency.

11. A parameter design device of a resonant converter, comprising: a memory; and a processor coupled with the memory, the processor being configured to: determine a loss versus magnetizing inductance curve of the resonant converter based on a zero-voltage switching requirement of a primary-side switching device and a zero-current switching requirement of a secondary-side switching device of the resonant converter, the loss comprising a switching loss and an on-state loss; determine a magnetizing inductance value corresponding to a loss minimum point based on the loss versus magnetizing inductance curve of the resonant converter as a magnetizing inductance theoretical value meeting an efficiency optimal condition; determine a magnetizing inductance critical value meeting a constraint condition of an engineering off-current based on the constraint condition; and determine a magnetizing inductance design value based on the magnetizing inductance theoretical value and the magnetizing inductance critical value.

12. The parameter design device according to Claim 11, wherein The processor is further configured to: determine the magnetizing inductance theoretical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being less than the magnetizing inductance critical value; and determine the magnetizing inductance critical value as the magnetizing inductance design value in response to the magnetizing inductance theoretical value being greater than the magnetizing inductance critical value.

13. The parameter design device according to Claim 11, wherein The processor is further configured to: determine a turns ratio of a high-frequency transformer in the resonant converter based on a performance index requirement of the resonant converter; determine a resonant frequency of the resonant converter based on a power level of the resonant converter and a model of a switching device; and substitute the turns ratio, the resonant frequency and other constant parameters into a loss versus magnetizing inductance formula of the resonant converter to determine the loss versus magnetizing inductance curve.

14. The parameter design device according to Claim 13, wherein The processor is further configured to: establish the loss versus magnetizing inductance formula of the resonant converter.

15. The parameter design device according to Claim 14, wherein The processor is further configured to: determine a relationship formula of a root mean square value of a resonant current versus a magnetizing inductance based on the magnetizing inductance achieving a zero-voltage switching requirement and a relationship of a resonant period, a switching period and a dead time, the relationship formula involving an influence of the dead time on the magnetizing inductance; determine a relationship formula of a root mean square value of a secondary-side current versus the magnetizing inductance based on a relationship of a resonant current, a magnetizing current and a load current; determining the turn-on loss and the turn-off loss of the primary-side switching device and the turn-on loss and the turn-off loss of the secondary-side switching device based on the zero-voltage switching requirement of the primary-side switching device, the zero-current switching requirement of the secondary-side switching device, a relationship between the effective value of the resonant current and the magnetizing inductance, and a relationship between the effective value of the secondary-side current and the magnetizing inductance; and obtaining the sum of the turn-on loss and the turn-off loss of the primary-side switching device and the secondary-side switching device as a relationship between the loss of the resonant converter and the magnetizing inductance.

16. The parameter design device according to Claim 13, wherein The processor is further configured to: determine the turns ratio by using the input rated voltage and the output rated voltage of the resonant converter.

17. The parameter design device according to Claim 13, wherein The processor is further configured to: determine the inductance ratio design value of the resonant converter by using the step-by-step approximation method; determine the resonant inductance design value of the resonant converter based on the inductance ratio design value and the magnetizing inductance design value; and determine the resonant capacitance design value of the resonant converter based on the resonant inductance design value and the resonant frequency.

18. The parameter design device according to Claim 17, wherein The processor is further configured to: assume the inductance ratio value of the resonant converter; draw the gain curve corresponding to the assumed inductance ratio value by using the FHA analysis method to determine whether the gain meets the performance index requirement of the resonant converter; and determine the maximum value of the inductance ratio value meeting the performance index requirement of the resonant converter as the set value of the inductance ratio.

19. The parameter design device according to Claim 17, wherein The processor is further configured to: The resonance inductance is calculated using the formula L r = L m / k, where L r is the resonance inductance design value, L m is the excitation inductance design value, and k is the inductance ratio design value.

20. The parameter design device of Claim 17, wherein, The processor is further configured to: Using the resonant capacitor calculation formula The resonant capacitor design value is calculated, wherein L r is the resonant inductance design value, f r is the resonant frequency.

21. A computer storage medium having stored thereon a computer program, characterized in that The computer program, when executed, implements the steps of the parameter design method of the resonant converter according to any one of claims 1-10.

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