CN114169278A - Parameter design method and device for resonant converter - Google Patents

Abstract

The invention provides a parameter design method of a resonant converter, which comprises the following steps: determining a relation curve of loss of the resonant converter and excitation inductance 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, wherein the loss comprises switching loss and on-state loss; and determining a design value of the excitation inductance meeting the optimal efficiency condition based on a relation curve of the loss of the resonant converter and the excitation inductance.

Description

Parameter design method and device for resonant converter

technical field

The invention relates to the field of resonant converters, in particular to a parameter design method and device of a resonant converter.

Background technique

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

In recent years, with the rapid development of high-frequency power electronic technology, isolated resonant converters with power semiconductor devices as the core have been widely used. Considering the weight and volume requirements of high-power converters, increasing the switching frequency of the converter has become an effective means; however, a higher switching frequency will inevitably lead to a larger switching loss, and the larger switching loss will affect the design and heat dissipation of the converter. Bringing huge challenges, the size and weight of the system are also limited. The LLC resonant converter is a kind of resonant converter. Compared with the traditional hard switching, the LLC resonant converter can realize the zero-voltage turn-on (ZVS) of the primary power tube and the zero-current turn-off (ZCS) of the secondary diode. Therefore, the loss of the converter is greatly reduced, and the purpose of weight reduction and volume reduction is achieved. Compared with other soft-switching technologies, LLC resonant converters do not require additional hardware circuits, the voltages of the power devices are only the bus voltage, and the output filter is simple in design. It has the advantages of simple structure and high reliability. great application prospects.

The topology of the LLC resonant converter is shown in Figure 1, where V _in is the input voltage, C ₁ and C ₂ are the support capacitors for the upper half voltage and the lower half voltage, respectively, and S ₁ to S ₈ are the full-bridge three-level source. The switch tubes on the side, D ₁₁ ~ D ₁₄ are clamping diodes; L _m , L _r , _Cr are the excitation inductance, resonance inductance and resonance capacitance of the resonant cavity, i _Lr is the resonance current, i _Lm is the excitation current, i _sec ' is the current converted from the secondary side current to the primary side, i _sec is the secondary side current; n is the transformation ratio of the high-frequency transformer, V ₁ ～ V ₄ are the secondary side switch tubes, C _d is the output support capacitor, and R _L is the load, V ₀ is the output voltage. Reasonable design of LLC resonant cavity parameters can realize wide-range adjustable output voltage, primary side switching device realizes ZVS, and secondary side switching device realizes ZCS. Therefore, the design of LLC resonance parameters is related to the performance of the converter.

The traditional design idea of LLC resonant converter: The traditional design idea of LLC resonant converter firstly 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 by calculation, And further determine the frequency range of the output voltage; thirdly, select the Q value of the converter reasonably under the condition of ensuring the realization of soft switching; after completing the above steps, the design of the parameters of the resonant cavity can be completed.

The shortcomings of the traditional LLC-type resonator parameter design mainly lie in the following aspects:

1. The traditional LLC resonator parameter design is based on the gain of the converter, while the high-power LLC converter basically works with a constant DC gain ratio. A constant DC gain ratio indicates that the converter works approximately at a fixed frequency, and it is not expected that the switching frequency range of the converter is too wide, which will also bring a burden to the design of high-frequency transformers.

2. The traditional LLC resonator parameter design is that the charge transfer of the junction capacitance can be completed within the dead time to realize ZVS, and the influence of the dead time is not considered. In low-power applications, the proportion of dead time is small and can be ignored, while in high-power applications, excessive dead time will cause the resonant current to cross zero in reverse, and ZVS cannot be achieved.

3. The traditional LLC resonator parameter design cannot guarantee the optimum efficiency of the converter. Usually, according to engineering experience, the larger the magnetizing inductance, the higher the efficiency, but in fact, the efficiency and the magnetizing inductance are not simply 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 requirements has infinite solutions. Therefore, there are also infinite solutions for the excitation inductance, and the converter efficiency under the selected excitation inductance is not necessarily the highest. excellent.

4. The traditional LLC resonator parameter design does not take into account the engineering constraints. The larger the magnetizing inductance, the smaller the turn-off current. Consider the turn-off delay of the switch (the smaller the turn-off current, the longer the turn-off time). If it is not completely turned off within the dead time, the same bridge arm will When the other switch tube is turned on, a reverse inrush current will inevitably occur, which threatens the safe operation of the converter.

Therefore, in order to solve the above problems, the present invention aims to provide a design method for a resonant cavity converter, which can realize the optimal design of the converter's efficiency.

SUMMARY OF THE INVENTION

A brief summary of one or more aspects is given below to provide a basic understanding of the aspects. This summary is not an exhaustive overview of all contemplated aspects and is neither intended to identify key or critical elements of all aspects nor attempt to 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.

According to an aspect of the present invention, there is provided a parameter design method for a resonant converter, comprising: determining the resonant converter 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 of the resonant converter A relationship curve between the loss of the resonant converter and the excitation inductance, the loss includes switching loss and on-state loss; and a design value of the excitation inductance that satisfies the optimal efficiency condition is determined based on the relationship between the loss of the resonant converter and the excitation inductance.

Further, the determination of the excitation inductance value based on the relationship between the loss of the resonant converter and the excitation inductance so that the resonant converter can reach the optimal efficiency condition includes: based on the relationship between the loss of the resonant converter and the excitation inductance. determining the excitation inductance value corresponding to the lowest loss point as the theoretical excitation inductance value satisfying the optimal efficiency condition; determining the excitation inductance critical value satisfying the constraint condition based on the constraint condition of the engineered turn-off current; and based on the excitation inductance theory value and the magnetizing inductance threshold determine the magnetizing inductance design value.

Further, the determining the design value of the excitation inductance based on the theoretical value of the excitation inductance and the critical value of the excitation inductance includes: in response to the theoretical value of the excitation inductance being less than or equal to the critical value of the excitation inductance, the excitation A theoretical value of inductance is determined as the design value of the excitation inductance; and in response to the theoretical value of the excitation inductance being greater than the threshold value of the excitation inductance, the threshold value of the excitation inductance is determined as the design value of the excitation inductance.

Furthermore, determining the relationship curve between the loss of the resonant converter and the excitation inductance 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 of the resonant converter includes: based on the resonant converter The performance index of the resonant converter requires determining the transformation ratio of the high-frequency transformer in the resonant converter; determining the resonant frequency of the resonant converter based on the power level of the resonant converter and the model of the switching device; and combining the transformation ratio, The resonant frequency and other constant parameters are substituted into the loss vs. magnetizing inductance relationship of the resonant converter to determine the loss vs. magnetizing inductance curve.

Further, the parameter design method further includes: establishing a relationship between the loss of the resonant converter and the excitation inductance.

Further, establishing the relationship between the loss of the resonant converter and the excitation inductance includes: realizing the zero-voltage switching requirement based on the excitation inductance and determining the resonant current by using the relationship between the resonance period, the switching period and the dead time. The relationship between the effective value and the excitation inductance, the relationship involves the effect of the dead time on the excitation inductance; based on the relationship between the resonant current, the excitation current and the load current, the effective value of the secondary current and the excitation inductance are determined. relationship; 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 rms value of the resonant current and the excitation inductance, and the rms value of the secondary side current and the excitation The relationship of the inductance determines 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; and obtains the primary side switching device and the secondary side switching device. The sum of the turn-on loss and turn-off loss is used as the relationship between the loss of the resonant converter and the excitation inductance.

Further, the determining the transformation ratio of the high-frequency transformer in the resonant converter based on the performance index requirements of the resonant converter includes: determining the transformation ratio by using the input rated voltage and the output rated voltage of the resonant converter. Compare.

Further, the parameter design method further includes: determining the inductance ratio design value of the resonant converter by using a step-by-step approximation method; determining the resonant converter based on the inductance ratio design value and the excitation 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.

Further, the step-by-step approximation method to determine the design value of the inductance ratio of the resonant converter includes: assuming the inductance ratio of the resonant converter; using the FHA analysis method to draw a gain curve corresponding to the assumed inductance ratio to Determining whether the gain meets the performance index requirements of the resonant converter; and determining the maximum value of the inductance ratios that meet the performance index requirements of the resonant converter as the set value of the inductance ratio.

Further, the determining the resonant inductance of the resonant converter based on the inductance ratio design value and the excitation inductance design value includes: calculating the resonant inductance by using the resonant inductance calculation formula L _r =L _m /k design value, wherein L _r is the design value of the resonant inductance, L _m is the design value of the excitation inductance, and k is the design value of the inductance ratio.

计算出所述谐振电容设计值，其中，L_r为所述谐振电感设计值，f_r为所述谐振频率。Further, the determining the resonant capacitor design value of the resonant converter based on the resonant inductance and the resonant frequency includes: using a resonant capacitor calculation formula

The design value of the resonance capacitor is calculated, wherein L _r is the design value of the resonance inductance, and _fr is the resonance frequency.

According to another aspect of the present invention, there is also provided a parameter design device for a resonant converter, comprising: a memory; and a processor, the processor is coupled to the memory, the processor is configured to: based on the resonance 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 converter determine a loss versus magnetizing inductance curve of the resonant converter, the loss including switching loss and on-state loss; and based on The relationship curve between the loss of the resonant converter and the excitation inductance determines the design value of the excitation inductance that satisfies the optimal efficiency condition.

Furthermore, the processor is further configured to: determine the excitation inductance value corresponding to the lowest loss point based on the relationship between the loss of the resonant converter and the excitation inductance as the theoretical value of the excitation inductance that satisfies the optimal efficiency condition; Engineering the constraints of the turn-off current to determine a magnetizing inductance threshold value that satisfies the constraints; and determining the magnetizing inductance design value based on the magnetizing inductance theoretical value and the magnetizing inductance threshold value.

Still further, the processor is further configured to: in response to the theoretical value of the exciting inductance being less than the critical value of the exciting inductance, determine the theoretical value of the exciting inductance as the design value of the exciting inductance; and in response to the The theoretical value of the excitation inductance is greater than the threshold value of the excitation inductance, and the threshold value of the excitation inductance is determined as the design value of the excitation inductance.

Further, the processor is further configured to: determine the transformation ratio of the high frequency transformer in the resonant converter based on the performance index requirements of the resonant converter; based on the power level and switching devices of the resonant converter determine the resonant frequency of the resonant converter; and substitute the transformation ratio, the resonant frequency and other constant parameters into the relationship between the loss and the excitation inductance of the resonant converter to determine the loss and the excitation inductance relationship curve.

Still further, the processor is further configured to: establish a relationship between the losses of the resonant converter and the excitation inductance.

Further, the processor is further configured to: realize the zero-voltage switching requirement based on the excitation inductance and determine the relationship between the effective value of the resonance current and the excitation inductance by using the relationship between the resonance period, the switching period and the dead time, The relational expression relates to the influence of the dead time on the excitation inductance; the relational expression between the effective value of the secondary current and the excitation inductance is determined based on the relationship between the resonant current, the excitation current and the load current; based on the primary switch The zero-voltage switching requirements of the device, the zero-current switching requirements of the secondary switching devices, the relationship between the effective value of the resonant current and the excitation inductance, and the relationship between the effective value of the secondary current and the excitation inductance determine the original turn-on loss and turn-off loss of the side switching device and turn-on loss and turn-off loss of the secondary side switching device; and finding the sum of the turn-on loss and turn-off loss of the primary side switching device and the secondary side switching device as the relationship between the loss of the resonant converter and the excitation inductance.

Still further, the processor is further configured to: determine the transformation ratio using an input voltage rating and an output voltage rating of the resonant converter.

Furthermore, the processor is further configured to: determine the inductance ratio design value of the resonant converter by using a step-by-step approximation method; determine the resonant transformation based on the inductance ratio design value and the excitation 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.

Further, the processor is further configured to: assume the inductance ratio of the resonant converter; use the FHA analysis method to draw a gain curve corresponding to the assumed inductance ratio to determine whether the gain satisfies the resonant converter. performance index requirements; and determining the maximum value of the inductance ratios satisfying the performance index requirements of the resonant converter as the set value of the inductance ratio.

Furthermore, the processor is further configured to: calculate the resonant inductance design value using the resonant inductance calculation formula L _r =L _m /k, where L _r is the resonant inductance design value, and L _m is the excitation Design value of inductance, k is the design value of inductance ratio.

计算出所述谐振电容设计值，其中，L_r为所述谐振电感设计值，f_r为所述谐振频率。Further, the processor is further configured to: use the resonance capacitance calculation formula

The design value of the resonance capacitor is calculated, wherein L _r is the design value of the resonance inductance, and _fr is the resonance frequency.

According to yet another aspect of the present invention, there is also provided a computer storage medium on which a computer program is stored, and when the computer program is executed, implements the steps of the method for designing parameters of a resonant converter according to any one of the above.

The resonant converter designed based on the parameter design method of the resonant converter of the present invention can maintain high-efficiency operation, reduce the cooling design difficulty of the resonant converter, help reduce the volume and weight of the converter, and improve the performance of the converter. power density.

The parameter design method of the resonant converter of the present invention, from the point of view of the turn-on and turn-off characteristics of the power semiconductor device, through rational selection of the turn-off current and further selection of the excitation inductance, ensures that the power switch tube works in a safe area, thereby ensuring the resonance The converter operates safely.

The parameter design method of the resonant converter of the present invention does not require repeated iterations of the design of the excitation inductance, and the solution process is simple.

The parameter design method of the resonant converter of the present invention is simple in principle and easy to implement in engineering.

Description of drawings

The above-described features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings.

1 is a schematic topological structure diagram of a conventional full-bridge three-level resonant converter according to the prior art;

2 is a schematic flowchart of a parameter design method in an embodiment according to an aspect of the present invention;

3A is a schematic diagram of an equivalent topology according to an equivalent topology of a resonant converter;

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

4 is a schematic partial flowchart of a parameter design method in an embodiment according to an aspect of the present invention;

5A is a schematic diagram showing the relationship between the effective value of the resonance current and the excitation inductance in a specific embodiment according to an aspect of the present invention;

FIG. 5B is a schematic diagram showing a curve relationship between the effective value of the secondary current and the excitation inductance in a specific embodiment according to an aspect of the present invention;

6 is a schematic partial flowchart of a parameter design method in an embodiment according to an aspect of the present invention;

FIG. 7 is a schematic diagram showing a curve relationship between the loss of the resonant converter and the excitation inductance in a specific embodiment according to an aspect of the present invention;

8 is a schematic partial flowchart of a parameter design method in an embodiment according to an aspect of the present invention;

9 is a schematic partial flowchart of a parameter design method in an embodiment according to an aspect of the present invention;

10 is a schematic partial flowchart of a parameter design method in an embodiment according to an aspect of the present invention;

FIG. 11 is a schematic block diagram of a parameter design apparatus in an embodiment according to another aspect of the present invention.

Detailed ways

The following description is presented to enable any person skilled in the art to make and use the invention and to integrate it into a specific application context. Various modifications, and various uses in different applications will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to a wider range of embodiments. Thus, the present invention is not limited to the embodiments set forth herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the practice of the present invention may not necessarily be limited to these specific details. In other words, well-known structures and devices are shown in block diagram form without detail in order to avoid obscuring the present invention.

The reader is drawn to all documents and documents that are filed concurrently with this specification and that are open to public inspection with this specification, and the contents of all such documents and documents are incorporated herein by reference. All features disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless directly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is only one example of a group of equivalent or similar features.

Note that where used, the signs left, right, front, back, top, bottom, forward, reverse, clockwise and counterclockwise are used for convenience only and do not imply any specific fixation direction. In fact, they are used to reflect the relative position and/or orientation between parts of the object. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In the description of the present invention, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense, unless otherwise expressly specified and limited, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Note that in the case of use, further, preferably, further and more preferably is a simple beginning of the description of another embodiment on the basis of the foregoing embodiment, which is further, preferably, further The content of the ground or preferably the backband is combined with the previous embodiment as a complete composition of another embodiment. A further embodiment can be formed by arbitrarily combining several further, better, further or more optimal arrangements of the rear bands of the same embodiment.

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are only exemplary, and should not be construed as any limitation to the protection scope of the present invention.

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

In one embodiment, as shown in FIG. 2 , the parameter design method 200 of the resonant converter includes steps S210-S220.

Wherein, step S210 is: based on the zero voltage switch (Zero Voltage Switch, ZVS) requirement of the primary side switching device of the resonant converter and the zero current switch (ZCS) requirement of the secondary side switching device to determine the resonant converter. Losses versus magnetizing inductance, including switching losses and on-state losses.

The equivalent topology of the resonant converter is shown in Figure 3A, and the corresponding current waveform is shown in Figure 3B, where i _Lr is the resonant current, _Vin is the input voltage, L _r is the resonant inductance, C _r is the resonant capacitor, L _m is the excitation inductance, I _Lm is the excitation current, I _sec ' is the effective value of the primary current, and R _ac is the equivalent load resistance. Those skilled in the art can understand that the equivalent topology diagram shown in FIG. 3A can be applied to resonant converters of various topology types such as half-bridge, full-bridge, two-level, three-level or multi-level. The switch tube power device used therein may adopt IGBT, MOSFET, SiC or other existing or to-be-existing semiconductor devices.

Specifically, the relationship between the loss of the resonant converter and the excitation inductance can be established first 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 of the resonant converter.

The steps of establishing the relationship between the loss of the resonant converter and the excitation inductance may be shown in FIG. 4 , including steps S410 to S440 .

Wherein, step S410 is: realizing the zero-voltage switching requirement based on the excitation inductance and determining the relationship between the effective value of the resonance current and the excitation inductance by using the relationship between the resonance period, the switching period and the dead time.

Based on Figures 3A and 3B, when the switching frequency _fsw and the resonant frequency _fr of the resonant converter are the same, the expressions of the resonant current and the excitation current are respectively as follows:

Among them, I _pri is the effective value of the resonant current, _wr is the resonant angular frequency and ω _r =2πf _r , θ is the initial phase angle, V ₀ is the voltage across the load, n is the transformation ratio, and T _r is the resonant period.

During a half switching cycle, the average value of the output current satisfies the following formula:

Among them, T _s is the switching period.

Considering the effect of dead time, the relationship between resonance period, switching period and dead time is as follows:

T _s =T _r +2T _d (4)

where T _d is the dead time.

In order to ensure that the primary-side switching device of the resonant converter achieves the zero-voltage switching requirement, the charge transfer on the junction capacitance needs to be completed within the dead time. Therefore, the critical condition for the excitation inductance to achieve ZVS is:

Among them, C _j is the junction capacitance, ξ is the coefficient.

The relationship between the effective value of the resonant current and the excitation inductance can be obtained from the simultaneous equations (1) to (5) as follows:

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

The specific address, resonant current, excitation current and load current satisfy the following equations:

i _sec '(t)=i _Lr (t)-i _Lm (t) (7)

Therefore, the effective value i _sec ' converted from the secondary current to the primary current is:

The relationship between the effective value of the primary current and the excitation inductance can be calculated as follows:

Then the relationship between the effective value of the secondary current and the excitation inductance is as follows:

I _sec =nI _sec ' (10)

Equation (9) is substituted into Equation (10), and the graphs of Equation (6) and Equation (10) are plotted. 5A and 5B show graphs of equations (6) and (10) in a specific embodiment. It can be seen from this specific embodiment that the relationship between the effective value of the resonant current and the excitation inductance and the relationship between the effective value of the secondary current and the excitation inductance do not change linearly, and there is an excitation inductance value that makes the corresponding resonance current The rms value and the current rms value of the secondary side are the smallest.

Further, step S430 is: 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 resonant current and the excitation inductance, and the secondary side current. The relationship between the effective value and the excitation inductance determines 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.

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

Since the primary side power device needs to realize 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 power device includes the on-state loss of the switch and the on-state loss of the diode. Among them, the proportion of the on-state loss of the diode is very small and can be ignored, so the on-state loss of the primary power device can only be considered as the on-state loss of the switch.

For the secondary diode, the secondary diode is in ZCS, there is no switching loss, only the on-state loss.

The switching loss of the resonant converter, the on-state loss of the primary switch and the on-state loss of the secondary diode are calculated respectively.

The switching losses of the resonant converter are as follows:

为关断电流，f_sw为开关频率，E_on为开通一次所需的能量(取0)，E_off为关断能量(查阅开关器件手册获得)，I_nom为开关器件的额定电流，U_nom为开关器件的额定电压，U_dc为开关器件关断时集电极和发射极(CE)之间的电压。in,

is the turn-off current, f _sw is the switching frequency, E _on is the energy required to turn on once (take 0), E _off is the turn-off energy (obtained from the manual of the switching device), I _nom is the rated current of the switching device, U _nom is the rated voltage of the switching device, and U _dc is the voltage between the collector and the emitter (CE) when the switching device is turned off.

The on-state losses of the primary switch are as follows:

P _{ss_igbt} = (V _{F0_125} · I _pri +R _{D0_125} · I _pri ² ) · D ₁ (12)

Among them, 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 leads, and D ₁ is the proportion of the on-state time.

The conduction losses of the secondary diode are as follows:

P _{ss_diode} =(V _F ·I _sec )·D ₂ (13)

Among them, V _F is the on-state voltage drop of the secondary diode, and D ₂ is the proportion of the on-state time of the secondary diode.

Further, step S440 is: 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 excitation inductance.

The total losses of the resonant converter are as follows:

P _{total_loss} = 8 · P _{sw_igbt} + 8 · P _{ss_igbt} + 4 · P _{ss_diode} (14)

Then the above equations (6), (10), (11), (12) and (13) can be substituted into equation (14) to obtain the relationship between the loss of the resonant converter and the excitation inductance:

除励磁电感L_m以外其他参数均为常量参数。Those skilled in the art can understand that among the parameters involved in formula (15), the transformation ratio _n and the resonant frequency fr can be determined based on the performance index requirements of the resonant converter, the power level and the type of the switching device, and the switching frequency f _sw is equal to the resonant frequency _fr ,

Other parameters except the excitation inductance L _m are constant parameters.

The above derivation calculation process does not need to be repeated in each design process, so the above formula (15) can be directly used to determine the excitation inductance. Then, as shown in FIG. 6, step S210 may include steps S211-S213.

Wherein, 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.

The performance index requirements of the resonant converter include the output rated voltage V _0N and the rated load _RL , and the transformation ratio n of the high-frequency transformer is determined according to the input rated voltage and output rated voltage, as shown in the following formula:

n=V _inN /V _0N (16)

Among them, V _inN is the input rated voltage, and V _0N is the output rated voltage.

Step S212 is: determining the resonant frequency of the resonant converter based on the power level of the resonant converter and the model of the switching device.

According to the power level of the converter and the model of the switching device, the resonant frequency _fr 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 and the resonant frequency _fr equal.

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

Substitute the above-mentioned transformation ratio _n and resonant frequency fr and other constant parameters determined based on the performance index requirements, power level and switching device type of the resonant converter into Equation (15) and plot to obtain the loss and excitation inductance relationship curve. FIG. 7 shows a relationship curve between the loss and the excitation inductance in a specific embodiment. As shown in FIG. 7 , based on the relationship curve, the excitation inductance value L _{m_cal} corresponding to the minimum loss value can be determined.

Step S220 is: determining a design value of the excitation inductance that satisfies the optimal efficiency condition based on the relationship between the loss of the resonant converter and the excitation inductance.

As shown in Figure 7, based on the relationship between the loss of the resonant inductance and the excitation inductance, the excitation inductance value L _{m_cal} corresponding to the minimum loss is determined as the theoretical value of the excitation inductance that satisfies the optimal conditions for the efficiency of the resonant converter, and the excitation inductance design The value needs to meet the engineering requirements, so it can only be used when the theoretical value of the excitation inductance meets the engineering requirements.

Further, as shown in FIG. 8 , step S220 may include steps S221 to S223.

Wherein, step S221 is: determining the excitation inductance value corresponding to the lowest point of the loss based on the relationship curve between the loss and the excitation inductance as the theoretical value of the excitation inductance satisfying the optimal efficiency condition.

Step S222 is: determining a threshold value of the excitation inductance that satisfies the constraint condition based on the constraint condition of the engineered turn-off current.

Those skilled in the art can understand that the _theoretical value of the excitation inductance is not necessarily achievable in engineering. When the tube is turned on, there will be a current spike, which seriously threatens the reliable operation of the converter. Therefore, the constraints for establishing the engineered turn-off current are as follows:

Based on Equation (17), the threshold value L _{m_tem} of the excitation inductance satisfying the constraints of the engineered turn-off current can be obtained, as shown in Equation (18):

Among them, I _{off_tem} is the critical value of the switch-off current.

Further, step S223 is: determining the design value of the excitation inductance based on the theoretical value of the excitation inductance and the threshold value of the excitation inductance.

Specifically, when the theoretical value of the exciting inductance L _{m_cal} satisfies the constraints of the engineered off current, that is, in response to the theoretical value of the exciting inductance L _{m_cal being} less than or equal to the critical value of the exciting inductance I _{off_tem} , the theoretical value of the exciting inductance L _{m_cal} is determined as the design of the exciting inductance Value _{Im_opt} .

When the theoretical value of the exciting inductance L _{m_cal} does not meet the constraints of the engineered turn-off current, that is, in response to the theoretical value of the exciting inductance L _{m_cal being} greater than the critical value of the exciting inductance I _{off_tem} , the critical value of the exciting inductance I _{off_tem} is determined as the design value of the exciting inductance I _{m_opt} .

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

Further, the parameter design method 200 of the resonant converter may further include steps S230-250, as shown in FIG. 9 .

Wherein, step S230 is: adopting a step-by-step approximation method to determine the design value of the inductance ratio of the resonant converter.

The step-by-step approximation method refers to starting from some easy-to-apply conditions or some weakened conditions that are intrinsically related to the essence of the problem, and then gradually expanding (or narrowing) the scope, gradually approaching, and finally reaching the solution required by the problem. Methods. The specific steps may be shown in FIG. 10, including steps S231-S233.

Step S231 is: assuming the inductance ratio of the resonant converter.

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

The gain of the resonant converter can be expressed as:

f_sw为谐振变换器的开关频率，f_r为谐振频率，L_r为谐振电感，C_r为谐振电容且

R_ac为负载等效电阻，k为假设的电感比值。in,

_fsw is the switching frequency of the resonant converter, _{fr is the resonant frequency, L r is} the resonant inductance, C _r is the resonant capacitance and

R _ac is the equivalent resistance of the load, and k is the assumed inductance ratio.

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, continue to perform step S231 until the occurrence of The inductance ratio that makes the gain meet the performance index requirements of the resonant converter.

Step S233 is: determining the maximum value of the inductance ratios satisfying the performance index requirements of the resonant converter as the inductance ratio setting value.

Those skilled in the art can understand that in the above step S231, the inductance ratio can be assumed from large to small; in step S232, the assumed inductance ratio is determined one by one whether the gain meets the performance index requirements of the resonant converter until the gain meets the resonant converter's performance index requirements. The inductance ratio required by the performance index; 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.

Optionally, the above-mentioned step S231 may be to assume a certain number of inductance ratios; step S232 may be to determine whether the gain meets the performance index requirements of the resonant converter for each assumed inductance ratio, so as to determine whether the assumed inductance ratios are such that Whether the gain meets the inductance ratio required by the performance index of the resonant converter; step S233 determines a maximum value as the inductance ratio setting value from the inductance ratios that make the gain meet the performance index of the resonant converter.

It can be understood that a larger inductance ratio that meets the performance index requirements of the resonant converter can be determined by the above two methods.

Step S240 is: determining a resonant inductance design value of the resonant converter based on the inductance ratio design value and the excitation inductance design value.

Specifically, the resonant inductance design value is calculated by using the resonant inductance calculation formula, and the resonance inductance calculation formula is as follows:

L _r =L _m /k (20)

Wherein, L _r is the design value of the resonance inductance, L _m is the design value of the excitation inductance, and k is the design value of the inductance ratio.

Step S250 is: determining a resonant capacitor design value of the resonant converter based on the resonant inductance design value and the resonant frequency.

Specifically, the resonant capacitor design value is calculated using the resonant capacitor calculation formula, and the resonant capacitor calculation formula is as follows:

Among them, L _r is the design value of the resonant inductance, and _fr is the resonant frequency.

Although the above-described methods are illustrated and described as a series of acts for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the acts, as some acts may occur in a different order in accordance with one or more embodiments and/or occur concurrently with other actions from or not shown and described herein but understood by those skilled in the art.

According to another aspect of the present invention, a parameter design device for a resonant converter is also provided.

In one embodiment, as shown in FIG. 11 , the parameter design apparatus 1100 of the resonant converter includes a memory 1110 and a processor 1120 .

The memory 1110 is used to store computer programs.

The processor 1120 is coupled to the memory 1110 for executing computer programs stored on 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 foregoing embodiments are implemented.

According to yet another aspect of the present invention, a computer storage medium is also provided, and a computer program is stored on the computer storage medium, and when the computer program is executed, the steps of the parameter design method 200 in any of the foregoing embodiments are implemented.

Those of skill in the art would understand that information, signals and data may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and chips recited throughout the above description may be composed of voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or optical particles, or any combination to represent.

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 may 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 on the specific application and design constraints imposed on the overall system. Skilled artisans may 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 invention.

The various illustrative logic modules, and circuits described in connection with the embodiments disclosed herein may be implemented using general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), or other programmable Logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein are implemented or performed. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

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

In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may 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 medium can be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, or can be used to carry or store instructions or data structures in the form of Any other medium that conforms to program code and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using 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 are often reproduced magnetically data, and discs reproduce the data optically with a laser. Combinations of the above should also be included within the scope of computer-readable media.

The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. However, it should be understood that the protection scope of the present invention should be determined by the appended claims, and should not be limited to the specific structures and components of the above-explained embodiments. Those skilled in the art can make various changes and modifications to the embodiments within the spirit and scope of the present invention, and these changes and modifications also fall within the protection scope of the present invention.

Claims (23)

1. A method of parametric design of a resonant converter, comprising:

determining a relation curve of loss of the resonant converter and excitation inductance 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, wherein the loss comprises switching loss and on-state loss; and

and determining a design value of the excitation inductance meeting the optimal efficiency condition based on a relation curve of the loss of the resonant converter and the excitation inductance.

2. The parameter design method of claim 1, wherein determining an excitation inductance value that causes the resonant converter to reach an efficiency optimization condition based on a loss versus excitation inductance curve of the resonant converter comprises:

determining an excitation inductance value corresponding to the lowest loss point based on a relation curve of the loss of the resonant converter and the excitation inductance to serve as an excitation inductance theoretical value meeting an efficiency optimal condition;

determining an excitation inductance critical value meeting the constraint condition based on the constraint condition of the engineering turn-off current; and

and determining the excitation inductance design value based on the excitation inductance theoretical value and the excitation inductance critical value.

3. The parameter design method of claim 2, wherein said determining said excitation inductance design value based on said excitation inductance theoretical value and said excitation inductance critical value comprises:

determining the excitation inductance theoretical value as the excitation inductance design value in response to the excitation inductance theoretical value being less than or equal to the excitation inductance critical value; and

in response to the excitation inductance theoretical value being greater than the excitation inductance critical value, determining the excitation inductance critical value as the excitation inductance design value.

4. The parameter design method of claim 1, wherein determining a loss versus excitation inductance curve for 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 transformation ratio of a high frequency transformer within 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

and substituting the transformation ratio, the resonant frequency and other constant parameters into a relational expression of the loss and the excitation inductance of the resonant converter to determine a relational curve of the loss and the excitation inductance.

5. The parameter design method of claim 4, further comprising:

and establishing a relational expression of the loss of the resonant converter and the excitation inductance.

6. The parametric design method of claim 5, wherein the establishing a relationship of the resonant converter loss to excitation inductance comprises:

realizing a zero-voltage switching requirement based on an excitation inductor and determining a relational expression of an effective value of a resonant current and the excitation inductor by utilizing the relation among the resonant period, the switching period and the dead time, wherein the relational expression relates to the influence of the dead time on the excitation inductor;

determining a relational expression of an effective value of the secondary current and the excitation inductance based on the relation among the resonant current, the excitation 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 zero-voltage switching requirement of the primary side switching device, the zero-current switching requirement of the secondary side switching device, the relational expression of the effective value of the resonant current and the excitation inductance and the relational expression of the effective value of the secondary side current and the excitation inductance; and

and solving the sum of the turn-on loss and the turn-off loss of the primary side switching device and the secondary side switching device to be used as a relational expression of the loss of the resonant converter and the excitation inductance.

7. The parametric design method of claim 4, wherein the determining a transformation ratio of a high frequency transformer within the resonant converter based on performance index requirements of the resonant converter comprises:

the transformation ratio is determined using an input voltage rating and an output voltage rating of the resonant converter.

8. The parameter design method of claim 4, further comprising:

determining an inductance ratio design value of the resonant converter by adopting a successive approximation method;

determining 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 excitation inductance; and

and determining a design value of the resonant capacitance of the resonant converter based on the design value of the resonant inductance and the resonant frequency.

9. The parametric design method of claim 8, wherein the determining the design value of the inductance ratio of the resonant converter using successive approximation comprises:

assuming an inductance ratio of the resonant converter;

drawing a gain curve corresponding to the assumed inductance ratio by adopting an FHA analysis method to judge whether the gain meets the performance index requirement of the resonant converter; and

and determining the maximum value of the inductance ratio meeting the performance index requirement of the resonant converter as the set value of the inductance ratio.

10. The parametric design method of claim 8, wherein the determining a resonant inductance of the resonant converter based on the design inductance ratio value and the design excitation inductance value comprises:

calculation of formula L using resonant inductance_r＝L_mCalculating the designed value of the resonance inductance by the k, wherein L_rDesign value for the resonance inductance, L_mAnd k is a designed inductance ratio value.

11. The parametric design method of claim 8, wherein the determining a design value for a resonant capacitance of the resonant converter based on the resonant inductance and the resonant frequency comprises:

using resonant capacitance calculation formula

Calculating the designed value of the resonance capacitance, wherein L_rDesign value, f, for the resonance inductance_rIs the resonance frequency.

12. A parametric design apparatus for a resonant converter, comprising:

a memory; and

a processor coupled with the memory, the processor configured to:

determining a relation curve of loss of the resonant converter and excitation inductance 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, wherein the loss comprises switching loss and on-state loss; and

and determining a design value of the excitation inductance meeting the optimal efficiency condition based on a relation curve of the loss of the resonant converter and the excitation inductance.

13. The parametric design apparatus of claim 11, wherein the processor is further configured to:

determining an excitation inductance value corresponding to the lowest loss point based on a relation curve of the loss of the resonant converter and the excitation inductance to serve as an excitation inductance theoretical value meeting an efficiency optimal condition;

determining an excitation inductance critical value meeting the constraint condition based on the constraint condition of the engineering turn-off current; and

and determining the excitation inductance design value based on the excitation inductance theoretical value and the excitation inductance critical value.

14. The parametric design apparatus of claim 13, wherein the processor is further configured to:

determining the excitation inductance theoretical value as the excitation inductance design value in response to the excitation inductance theoretical value being smaller than the excitation inductance critical value; and

in response to the excitation inductance theoretical value being greater than the excitation inductance critical value, determining the excitation inductance critical value as the excitation inductance design value.

15. The parametric design apparatus of claim 12, wherein the processor is further configured to:

determining a transformation ratio of a high frequency transformer within 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

and substituting the transformation ratio, the resonant frequency and other constant parameters into a relational expression of the loss and the excitation inductance of the resonant converter to determine a relational curve of the loss and the excitation inductance.

16. The parametric design apparatus of claim 15, wherein the processor is further configured to:

and establishing a relational expression of the loss of the resonant converter and the excitation inductance.

17. The parametric design apparatus of claim 16, wherein the processor is further configured to:

realizing a zero-voltage switching requirement based on an excitation inductor and determining a relational expression of an effective value of a resonant current and the excitation inductor by utilizing the relation among the resonant period, the switching period and the dead time, wherein the relational expression relates to the influence of the dead time on the excitation inductor;

determining a relational expression of an effective value of the secondary current and the excitation inductance based on the relation among the resonant current, the excitation 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 zero-voltage switching requirement of the primary side switching device, the zero-current switching requirement of the secondary side switching device, the relational expression of the effective value of the resonant current and the excitation inductance and the relational expression of the effective value of the secondary side current and the excitation inductance; and

and solving the sum of the turn-on loss and the turn-off loss of the primary side switching device and the secondary side switching device to be used as a relational expression of the loss of the resonant converter and the excitation inductance.

18. The parametric design apparatus of claim 15, wherein the processor is further configured to:

the transformation ratio is determined using an input voltage rating and an output voltage rating of the resonant converter.

19. The parametric design apparatus of claim 15, wherein the processor is further configured to:

determining an inductance ratio design value of the resonant converter by adopting a successive approximation method;

determining 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 excitation inductance; and

and determining a design value of the resonant capacitance of the resonant converter based on the design value of the resonant inductance and the resonant frequency.

20. The parametric design apparatus of claim 19, wherein the processor is further configured to:

assuming an inductance ratio of the resonant converter;

drawing a gain curve corresponding to the assumed inductance ratio by adopting an FHA analysis method to judge whether the gain meets the performance index requirement of the resonant converter; and

and determining the maximum value of the inductance ratio meeting the performance index requirement of the resonant converter as the set value of the inductance ratio.

21. The parametric design apparatus of claim 19, wherein the processor is further configured to:

calculation of formula L using resonant inductance_r＝L_mCalculating the designed value of the resonance inductance by the k, wherein L_rDesign value for the resonance inductance, L_mAnd k is a designed inductance ratio value.

22. The parametric design apparatus of claim 19, wherein the processor is further configured to:

using resonant capacitance calculation formula

Calculating the designed value of the resonance capacitance, wherein L_rDesign value, f, for the resonance inductance_rIs the resonance frequency.

23. A computer storage medium having a computer program stored thereon, wherein the computer program when executed implements the steps of a method of parametric design of a resonant converter as claimed in any of claims 1 to 11.

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