A small-loss inductance design method and electronic device

Abstract

The application relates to a small-loss inductance design method and electronic equipment. The method comprises the following steps: S1, determining target design indexes and maximum input voltage of inductance; S2, initially selecting a magnetic ring and a coil material; S3, constructing a total loss equation of inductance by taking the number of turns of the coil and the input voltage of the coil as variables; S4, confirming the target number of turns of the coil of the inductance based on the total loss equation, and obtaining a calculation input voltage corresponding to the maximum loss based on the total loss equation and the target number of turns of the coil; S5, confirming whether the calculation input voltage is consistent with the maximum input voltage, if yes, executing S6, otherwise executing S8; S6, obtaining an initial design result of the inductance; S7, obtaining and confirming whether the magnetic induction intensity of the inductance and the inductance inductance meet design requirements based on the initial design result; if yes, obtaining a final design result of the inductance, otherwise, executing S8; and S8, reselecting the magnetic ring and executing S3. In the design process, the application can accurately find a design point with the lowest loss, thereby reducing the production cost of products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inductors, and more particularly to a small-loss inductor design method and electronic equipment. BACKGROUND

[0002] With the development of the photovoltaic energy storage market, lithium batteries have been widely used due to their higher energy density than lead-acid batteries. Higher photovoltaic energy storage inverter efficiency, i.e. lower loss, is the main goal of product design in the industry. The main losses of the photovoltaic energy storage inverter are switch tube loss and magnetic device loss. The switch tube loss is mainly determined by the circuit topology and the performance of the switching device. After the circuit topology is determined, how to make the whole machine conversion efficiency the highest and how to design the magnetic device to make the loss of the magnetic device the lowest are important goals of the whole machine design.

[0003] The general practice in the industry for inductor design is to first determine the required inductance according to the given frequency, current, and ripple current, then preliminarily select a magnetic ring or refer to the magnetic ring or magnetic material used by a competitor, and then select a current density wire winding inductance according to the heat dissipation conditions. The inductance under a certain direct current bias is greater than the inductance designed before, which can generally meet the basic application requirements. However, due to the many working states of the converter, and the inductance under direct current bias will decay, thus causing the working state of the converter to change, how to find the lowest point of inductance loss under certain cost, i.e. how to accurately find the optimal design point, there is no unified design method. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a small-loss inductor design method and electronic equipment to solve the above technical defects of the prior art.

[0005] The technical solution adopted by the present application to solve the technical problem is: a small-loss inductor design method is constructed, comprising the following steps:

[0006] S1, determining the target design index of the inductor and the maximum input voltage corresponding to the inductor application scenario;

[0007] S2, preliminarily selecting a magnetic ring and a coil material;

[0008] S3, constructing a total loss equation of the inductor with the number of turns of the coil and the input voltage of the coil as variables according to the magnetic material of the magnetic ring and the coil material;

[0009] S4, confirming the target number of turns of the coil of the inductor based on the total loss equation and the maximum input voltage corresponding to the inductor application scenario, and obtaining a calculation input voltage corresponding to the maximum loss based on the total loss equation and the target number of turns of the coil.

[0010] S5, confirming whether the calculated input voltage is consistent with the maximum input voltage, if yes, executing step S6, otherwise executing step S8;

[0011] S6, determining the coil diameter of the inductor according to the target number of turns of the coil and the size of the magnetic ring to obtain an initial design result of the inductor;

[0012] S7, obtaining the magnetic induction intensity of the inductor and the inductance of the inductor based on the initial design result, and confirming whether the magnetic induction intensity and the inductance meet the design requirements; if yes, executing step S9, otherwise, executing step S8;

[0013] S8, reselecting a magnetic ring and executing step S3;

[0014] S9, obtaining a final design result of the inductor.

[0015] Preferably, in the small-loss inductor design method, the target design indicators of the inductor include: the current effective value Irms of the inductor, the minimum inductance of the inductor under direct current bias, the working switch frequency fs of the inductor, and the magnetic ring window occupancy rate Ku in the inductor.

[0016] Preferably, in the small-loss inductor design method, in the step S3, the total loss equation of the inductor is constructed with the number of turns of the coil and the coil input voltage as variables; including:

[0017] S31, constructing a copper loss equation of the inductor according to the current effective value equation of the inductor during operation;

[0018] S32, constructing an iron loss equation of the inductor according to the loss of the magnetic ring under alternating magnetic induction intensity;

[0019] S33, constructing a total loss equation of the inductor according to the copper loss equation of the inductor and the iron loss equation of the inductor.

[0020] Preferably, in the small-loss inductor design method, in step S4, the target number of turns of the inductor is confirmed based on the total loss equation and the maximum input voltage corresponding to the application scenario of the inductor, including:

[0021] Setting the coil input voltage in the total loss equation as the current maximum input voltage of the coil, and obtaining the number of turns of the coil with the minimum total loss as the target number of turns of the inductor.

[0022] Preferably, in the small-loss inductor design method, the method further includes: confirming the number of parallel strands of the coil according to the diameter of the coil material and the coil diameter of the inductor.

[0023] Preferably, in the small-loss inductor design method, in the step S7, the magnetic induction intensity of the inductor and the inductance of the inductor are obtained based on the initial design result, and it is determined whether the magnetic induction intensity and the inductance meet the design requirements.

[0024] The maximum magnetic induction intensity of the magnetic ring is obtained during the operation of the inductor, and it is determined that the magnetic induction intensity meets the design requirements when the maximum magnetic induction intensity of the magnetic ring is less than a first preset value.

[0025] The inductance of the inductor at the maximum input voltage is obtained according to the inductance equation and the DC bias curve, and it is determined that the inductance meets the design requirements when the inductance is greater than a second preset value.

[0026] Preferably, in the small-loss inductor design method, the reselected magnetic ring further comprises:

[0027] When the magnetic induction intensity does not meet the design requirements, a magnetic material with a greater saturation magnetic induction intensity is replaced or a large-size magnetic ring is replaced.

[0028] Preferably, in the small-loss inductor design method, the reselected magnetic ring comprises:

[0029] When the inductance does not meet the design requirements, a large-size magnetic ring is replaced or a magnetic material with higher DC bias resistance is replaced.

[0030] Preferably, in the small-loss inductor design method, the method further comprises:

[0031] The absolute temperature of the inductor at the highest environmental temperature is obtained, and when the absolute temperature exceeds a third preset value, a magnetic material with lower magnetic loss is selected or a large-size magnetic ring is replaced, and the step S3 is performed.

[0032] The application also provides an electronic device comprising a module for performing the method described above.

[0033] The small-loss inductor design method and the electronic device have the following beneficial effects: the design point with the lowest loss can be accurately found during the design process, the design efficiency of the inductor is greatly improved and the number of trial production is reduced under the same cost, and the cost of research and development samples and instrument equipment is also reduced. BRIEF DESCRIPTION OF DRAWINGS

[0034] The application will be further described below with reference to the drawings and embodiments, and the drawings show:

[0035] Figure 1is a structural schematic diagram of a small-loss inductor design method of the present application;

[0036] Figure 2 is an application circuit diagram of an inductor;

[0037] Figure 3 is a schematic diagram of the relationship between inductor operating current and voltage in an embodiment of the present application;

[0038] Figure 4 is a schematic diagram of the relationship between copper loss of an inductor and inductor turns in an embodiment of the present application;

[0039] Figure 5 is a schematic diagram of the relationship between iron loss of an inductor and inductor turns in an embodiment of the present application;

[0040] Figure 6 is a schematic diagram of the relationship between total loss of an inductor and inductor turns in an embodiment of the present application;

[0041] Figure 7 is a schematic diagram of the relationship between total loss of an inductor and battery voltage in an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will now be described in detail with reference to the accompanying drawings.

[0043] As shown in the drawings, Figure 1 in a first embodiment of the small-loss inductor design method of the present application, the following steps are included: S1, determining the target design indicators of the inductor and the maximum input voltage corresponding to the inductor application scenario; S2, initially selecting the magnetic ring and the coil material; S3, constructing the total loss equation of the inductor with the number of turns and the input voltage of the coil as variables based on the magnetic material of the magnetic ring and the coil material; S4, confirming the target number of turns of the coil of the inductor based on the total loss equation and the maximum input voltage corresponding to the inductor application scenario, and obtaining the calculated input voltage corresponding to the maximum loss based on the total loss equation and the target number of turns of the coil; S5, confirming whether the calculated input voltage is consistent with the maximum input voltage, if yes, executing step S6, otherwise executing step S8; S6, determining the coil diameter of the inductor based on the target number of turns of the coil and the size of the magnetic ring to obtain the initial design result of the inductor; S7, obtaining the magnetic induction intensity of the inductor and the inductance of the inductor based on the initial design result, and confirming whether the magnetic induction intensity and the inductance meet the design requirements; if yes, executing step S9, otherwise, executing step S8; S8, reselecting the magnetic ring and executing step S3; S9, obtaining the final design result of the inductor.

[0044] In one embodiment of the present invention, the inductor in a bidirectional BUCK-BOOST converter in a photovoltaic energy storage inverter is used as an example to introduce the entire inductor design process. Since BUCK mode corresponds to battery charging and BOOST mode corresponds to battery discharging, and the two operating modes are dual, the operating state and design method are the same for the inductor in the converter. Therefore, in this embodiment, only the design method for the inductor in the BOOST battery discharging state of the BUCK-BOOST converter is introduced. This method is suitable for the design of almost all types of inductors, such as PV boost BOOST inductors, inverter inductors, BUCK inductors, and various types of magnetic ring inductors in photovoltaic energy storage inverters. It is also suitable for the design of irregularly shaped powder core inductors. For ease of description, this embodiment only introduces the design method for magnetic ring-type powder core magnetic materials.

[0045] Based on step S1 above, the design specifications and electrical performance parameters of the inductor are determined. Figure 2 Taking this as an example, we construct an application environment for inductors. Inductors include inductor circuits used in BOOST converters. The main design specifications for inductors include the effective current Irms, the minimum required inductance (under DC bias) Lneed, the operating switching frequency fs, the magnetic ring window occupancy Ku, heat dissipation method and maximum losses, inductor cost, and size requirements. In one embodiment, the high-frequency ripple of the inductor is understood as the switching frequency. Specific parameters can be given as follows:

[0046] Set the maximum battery charging and discharging power P in_max =6000 W; Converter operating switching frequency f s =16.2 kHz: Maximum full-load bus voltage after battery voltage boosting Vbus = 425 V; Average value of maximum continuous charging and discharging current I bat_max =40 A; Minimum voltage of high-voltage battery pack V bat_mi n = 60 V; Maximum voltage of the high-voltage battery pack V bat_max =400V; Using battery voltage as the variable, define the battery output current function: Vbat = V bat_min V bat_min +0.1·VK V bat_max Here, the battery voltage Vbat is defined as a variable, increasing or decreasing in increments of 0.1V, with a minimum value of V. bat_min =60·V to the maximum value V bat_max =V varies between 400 and 400.

[0047] Define and list the battery terminal current I bat The equation relating the current to the battery voltage Vbat shows that the maximum current is limited when the battery voltage is low, and the maximum power is limited when the battery voltage is high.

[0048]

[0049] Inductors have different losses under different operating conditions. In order to avoid design errors (too much design margin is too costly) and to protect the temperature rise safety of the whole machine, the temperature rise of the inductor should not exceed the standard value under the worst conditions. This way, it will be safe under other conditions. Therefore, it is necessary to find the worst operating point of the inductor.

[0050] Ripple current formula based on BOOST converter Since the inductance L, power frequency fs, and output voltage Vo are constants, the maximum inductor ripple current can be calculated when the duty cycle D is 0.5, i.e., the input voltage Vin = 0.5 * Vo at this point. However, in this embodiment, the input current is already reduced due to power limitations when the input voltage reaches half the bus input voltage. Therefore, the worst-case operating point of the inductor will deviate from the half-bus input voltage point. In this embodiment, the worst-case operating voltage point of the inductor is the highest battery voltage point under maximum power, i.e., the maximum input voltage without triggering power limitations corresponding to the inductor application scenario. The maximum value of the total loss equation will be used to verify and confirm whether this voltage point is the point of maximum total loss.

[0051] In this embodiment, such as Figure 3 As shown, based on the battery terminal current I bat Plotting the curve using the (Vbat) equation yields a battery voltage of 150V corresponding to the worst-case inductance loss voltage point. Wherein, the charging and discharging current is I bat_max =40·A, min is a function that takes the minimum value among several values.

[0052] Based on step S2, the magnetic ring size and magnetic material selection are initially determined, with the magnetic ring material initially selected based on the inductor area-to-particle (Ap) method or the inductor on the reference prototype. For example, 2.2-inch, 2.5-inch, and 3.0-inch magnetic rings are commonly used in the photovoltaic inverter industry. Here, four NPH226060 magnetic rings are selected based on the reference prototype, with a permeability of 60. The material is gas-atomized iron-silicon NPH, which has the characteristic of lower high-frequency loss compared to iron powder cores, and its saturation magnetic induction intensity is B. s =1.2·T. The specifications of the magnetic ring include: outer diameter OD after coating = 58.04 mm, inner diameter ID after coating = 25.58 mm; coating thickness HT = 16.13 mm; inductance coefficient, i.e., single-turn inductance AL = 138·nH / N. 2 The magnetic permeability of the magnetic ring is u = 60; the equivalent magnetic circuit length of the magnetic ring is MPL = 12.5 cm; the volume of a single magnetic ring is Ve = 28.6 cm³. 3 The equivalent cross-sectional area of ​​the magnetic ring is Ae = 2.29 cm². 2 The number of parallel magnetic rings ncore = 4; all magnetic ring volume Ve in parallel all = Ve n core ; magnetic ring window occupancy generally does not exceed 0.45, here set K u = 0.43: copper wire resistivity at 20 degrees and standard atmospheric pressure p_Cu_20 = 1.724 10- 8 · Ω m; winding equivalent length, i.e. length of each turn MPT = [(OD-ID) + HT 2 n core ] mm; minimum number of turns N min = 8 Ts; maximum number of turns N max = 80 Ts; define the number of turns N L as a variable, with 1 turn as the minimum increment, between the minimum N min = 8 Ts and the maximum N max = 80 Ts, Ts is the number of turns unit, its expression can be Finally, the total winding length equation L_Cu(N L ) = MPT N L m: unit is meter m.

[0053] According to the magnetic ring parameter column to write the equation:

[0054]

[0055] Where, D set (N L ) is the winding of the circular copper wire diameter as a variable N L , unit is millimeter mm, does not contain the insulation of copper wire. Winding of the circular copper wire cross-sectional area as a variable N L : DC magnetic field strength equation is constructed as a variable N L and Vbat: Where, unit is Oersted Oe, MPL unit is cm (centimeter). Winding resistance is obtained as a variable N L to get the total resistance of the winding at a temperature of 100 C

[0056] Based on step S3, the total loss equation of the inductor can be constructed according to the copper loss and magnetic loss of the inductor, and the specific process is to construct the copper loss equation and the magnetic loss equation, respectively, and the sum of the copper loss and the magnetic loss is the total loss equation of the inductor. Wherein, the copper loss equation and the magnetic loss equation can be constructed by the following process.

[0057] According to the empirical formula coefficient of the NPH provided by the manufacturer and the magnetic permeability of 60 material, the DC bias equation is constructed as a variable N L and Vbat as follows:

[0058] The previous analysis showed that the battery voltage Vbat at this time was Vbat_set = 150 V.

[0059] With N L The current ripple equation of the inductor in BOOST mode is obtained by taking Vbat as a variable as follows:

[0060]

[0061] With N L Using Vbat as variables, the inductor operates in continuous mode. The effective value is calculated based on the superposition of a triangular wave and DC current. The equation for the effective value of the inductor current is as follows:

[0062]

[0063] Finally, we get N L The copper loss equation with Vbat as variables is:

[0064] P cu_NPH (N L ,Vbat)=I rms_NPH (N L (Vbat) 2 ·R_Cu_100(N L )·W;

[0065] Based on the copper loss equation, the copper loss curve is obtained at the battery voltage as follows: Figure 4 As shown, copper loss increases with the number of turns.

[0066] With N L The equation for AC magnetic flux density is constructed as follows, with Vbat as the variable:

[0067]

[0068] With N L The equation for the total magnetic flux density of the inductor is constructed as follows, with Vbat as the variable:

[0069]

[0070] With N L The loss equation for a unit volume of magnetic material under alternating magnetic induction intensity is constructed as follows, with Vbat as the variable:

[0071]

[0072] Because the magnetic ring experiences almost no loss under DC bias, its total loss under AC magnetic induction is simply the iron loss, expressed in N. L The iron loss equation is constructed as follows, with Vbat as the variable:

[0073] P fe_NPH (N L ,Vbat)=P cv_NPH (N L ,Vbat)·Ve all ;

[0074] The iron loss curve at a battery voltage of Vbat_set = 150 V, obtained from the iron loss equation, is shown below. Figure 5 As shown, the number of turns corresponding to the minimum iron loss can be obtained by solving the equation by finding its maximum value. The process of solving the iron loss equation separately can be achieved by transforming it from a binary equation to a univariate equation, i.e., setting the variable Vbat (battery voltage) to a fixed value Vbat_set, and obtaining the number of turns corresponding to the minimum iron loss. L A univariate equation with variable P fe_NPH1 (N L ) = P fe_NPH (N L (,Vbat_set), ultimately obtaining

[0075] N L_fe =round[Minimize(P fe_NPH1 N L )] = 30;

[0076] Among them, the iron loss equation with the number of turns as the variable is minimized, and the number of turns is obtained and rounded. At this time, the iron loss of the inductor ring is minimized, but the total loss is not necessarily minimized. The unit of number of turns is Ts (turns). The Minimize function is used to find the value of the variable when the function reaches its minimum value.

[0077] Finally, we get N L The equation for the total loss of the inductor, with Vbat as variables, is as follows:

[0078] P loss_all_NPH (N L ,Vbat)=P fe_NPH (N L ,Vbat)+P cu_NPH (N L ,Vbat);

[0079] Based on step S4, during the process of solving the total loss equation, the total loss curve of the inductor is obtained from the total loss equation of the inductor, as shown below. Figure 6 As shown, the number of turns corresponding to the minimum total inductor loss is obtained, that is, the number of turns corresponding to the minimum total loss is the optimal number of turns of the inductor.

[0080] The specific solving process can be that the variable Vbat of the total loss equation is set to the fixed value Vbat_set of the battery voltage, the total loss equation is changed from a binary equation to a unary equation, the total loss equation with the number of turns as the variable is minimized, and the number of turns is solved and rounded to the nearest integer, with the unit of the number of turns being Ts (turns), and the Minimize function is used to solve the value of the variable when the function reaches the minimum value.

[0081] P loss_all_NPH1 (N L )=P fe_NPH (N L ,Vbat_set)+P cu_NPH (N L ,Vbat_set);

[0082] N L_NPH =round(Minimize(P loss_all_NPH1 ,N L ))=23·Ts;

[0083] The variable N L in the total loss equation is set to the above solving value, the total loss equation is changed from a binary equation to a unary equation, and finally the relationship curve between the total loss of the inductor magnetic ring and the battery voltage in the full range is obtained when the number of turns NL_NPH, as shown in Figure 7 . The maximum value of the total loss obtained is the corresponding voltage, that is, the battery voltage point at which the total loss of the inductor is the largest.

[0084] P loss_all_NPH2 (Vbat)=P fe_NPH (N L_NPH ,Vbat)+P cu_NPH (N L_NPH ,Vbat);

[0085] Vbat_lossmax=Maximize(P loss_all_NPH2 ,Vbat)=150·V;

[0086] The total loss equation with the battery voltage as the variable is maximized, and the battery voltage value at this time is equal to the Vbat_set value. In addition, the number of turns can be set to other values, and the voltage value at this time is also Vbat_set, thereby verifying that the battery voltage is Vbat_set when the inductor loss is the worst voltage operating point. The Maximize function is used to solve the value of the variable when the function reaches the maximum value.

[0087] Based on step S6, the wire diameter of the single circular copper guide winding can be obtained, and the selected magnetic ring has a winding window, i.e., the inner circle of the magnetic ring. After selecting the wire diameter, the number of turns that can be wound is determined. In an embodiment, if the diameter of the single wire is too large and cannot be bent and wound, multiple wires can be used for parallel winding. For example, when the diameter of the single wire D set (N L_NPH ) = 3.498 mm, if the diameter of the selected single copper wire is D set_single = 2.0 mm, the number of copper wires needed for parallel winding under the same current-carrying copper wire cross-sectional area is solved and rounded to obtain where the round function is a rounding function, and multiple parallel winding inductors can reduce the impact of skin effect on copper loss.

[0088] After obtaining the initial design result of the inductor based on the above process, the magnetic induction B value and the inductance inductance corresponding to the initial design result are verified.

[0089] The selected magnetic material has a maximum limit value B s = 1.2 T, and it is derived that the magnetic induction of the inductor at the maximum current peak value does not exceed the maximum limit value of the magnetic material, otherwise the magnetic material with a larger saturation magnetic induction or the magnetic ring with a larger size needs to be replaced. Wherein, based on the above process, the maximum magnetic induction of the magnetic ring in operation is solved, B pk_NPH (N L_NPH ,Vbat_set) = 0.776 T, which satisfies the saturation magnetic induction of the selected magnetic material. At the same time, for the minimum inductance working in the BOOST mode, the maximum ripple coefficient does not exceed 1, based on the above process, the minimum inductance is obtained as

[0090] Combined with the DC bias curve, the inductance equation is constructed with N L and Vbat as variables as follows: L(N L ,Vbat) = μ NPH_u60 (N L ,Vbat)·n core ·AL·N L 2 ;

[0091] The inductance equation is substituted into the number of turns and the worst point battery voltage solved above, and the inductance equation is solved to obtain the inductance as follows: L(N L_NPH ,Vbat_set) = 187.9 uH; compared with L need_min = 149.8 uH, the former needs to be greater than the latter, otherwise the magnetic ring needs to be increased or the magnetic material with higher DC bias resistance needs to be replaced.

[0092] In an embodiment, after obtaining the final design result of the inductor based on the above process, the inductor can be directly manufactured. Considering that the inductor has various heat dissipation modes, in the photovoltaic energy storage inverter industry, the inductor generally needs to be filled with glue for heat dissipation, and the temperature-resistant insulation grade of the enameled wire is F grade or above, the worst absolute temperature under the highest environmental temperature is not more than 130 DEG C, and the absolute temperature measured at room temperature can be converted to obtain the absolute temperature under the highest environmental temperature. If the absolute temperature exceeds 130 DEG C, the total loss of the inductor needs to be further reduced. Since the design parameters of the inductor are the lowest loss under the selected magnetic ring and magnetic material, to reduce the loss, a magnetic material with lower magnetic loss or a larger volume of the magnetic ring needs to be selected, and the above calculation process needs to be repeated for optimal winding design.

[0093] Because the current design method of the magnetic ring inductor generally depends on experience and temperature rise comparison test, through continuous adjustment and manufacturing, and then through comparison test to find the appropriate inductor specification parameters. There is also a design method of simulating the entire inductor by using special magnetic circuit simulation software such as finite element simulation, by setting different magnetic materials and windings and quickly iterating to find the appropriate inductor design parameters, the magnetic material and winding parameters need to be repeatedly set, and this method is still a trial-and-error design method. There is also a method of directly testing the total loss of the wound inductor sample by using an inductor loss tester. At present, the high-current (more than 10A) inductor loss tester is expensive, and the instrument is mainly designed and developed by foreign-funded enterprises, and the precision is poor (more than 30% error), and it also has the disadvantage of not being able to superimpose high-frequency ripple. Although the inductor loss tester can quickly obtain the inductor loss value and perform comparison and iteration optimization, it is still a trial-and-error design method. Based on the process described in the present application, compared with the current inductor trial-and-error design method generally based on comparison test, the lowest loss design point can be quickly found, the design efficiency of the inductor is greatly improved and the number of manufacturing is reduced under the same cost, and the cost of research and development samples and instrument equipment is also reduced.

[0094] In the inductor total loss calculation process in the above process, the total loss of the inductor includes core loss and winding loss, i.e. iron loss and copper loss. The iron loss is mainly determined by the selected magnetic material. The performance of the MPP magnetic material is superior, the loss is small but the cost is high, and the general iron powder core magnetic ring has large loss but low cost. On the basis of the selected magnetic material, the diameter and number of turns of the copper wire need to be configured to allocate the ratio of iron loss and copper loss. For a power frequency transformer (generally using silicon steel sheet laminated magnetic material), the design standard is that the iron loss is equal to the copper loss under natural cooling condition. However, with the continuous development of magnetic material technology and the increasing diversification of heat dissipation requirements, the design method of iron loss equal to copper loss is not suitable. The main technical problem to be solved by the method provided by the present application is how to quickly calculate the inductor with the lowest total loss of copper loss and iron loss through the calculation method, so that the photovoltaic energy storage inverter achieves higher conversion efficiency.

[0095] In addition, an electronic device of the present application has functions to implement the corresponding steps performed in the above method. Each function can be implemented by hardware or by hardware executing corresponding software. The corresponding hardware or software includes one or more modules corresponding to the above functions. That is, the steps in the above method are performed by one or more modules respectively. The specific cooperation between each module can refer to the specific process of the above method, which will not be described here.

[0096] It can be understood that the above embodiments only express the preferred embodiments of the present application, which are described in detail and specifically, but cannot be understood as a limitation on the patent scope of the present application; it should be pointed out that for ordinary skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and some modifications and improvements can be made, which belong to the protection scope of the present application; therefore, any equivalent transformation and modification within the scope of the claims of the present application should belong to the scope of the claims of the present application.

Claims

1. A low-loss inductor design method, characterized by, The method comprises the following steps: S1, determining a target design index of an inductor and a maximum input voltage corresponding to an inductor application scenario; S2, preliminarily selecting a magnetic ring and a coil material; S3, constructing a total loss equation of the inductor with the number of turns of the coil and the input voltage of the coil as variables according to the magnetic material of the magnetic ring and the coil material; S4, confirming a target number of turns of the coil of the inductor based on the total loss equation and the maximum input voltage corresponding to the inductor application scenario, and obtaining a calculated input voltage corresponding to the maximum loss based on the total loss equation and the target number of turns of the coil; S5, confirming whether the calculated input voltage is consistent with the maximum input voltage, if yes, executing step S6, otherwise executing step S8; S6, determining the diameter of the coil of the inductor according to the target number of turns of the coil and the size of the magnetic ring to obtain an initial design result of the inductor; S7, obtaining the magnetic induction intensity of the inductor and the inductance of the inductor based on the initial design result, and confirming whether the magnetic induction intensity and the inductance both meet the design requirements; if yes, executing step S9, otherwise executing step S8; S8, reselecting the magnetic ring and executing step S3; S9, obtaining a final design result of the inductor.

2. The low-loss inductor design method of claim 1, wherein, The target design index of the inductor comprises: the current effective value Irms of the inductor, the minimum inductance of the inductor under direct current bias, the working switch frequency fs of the inductor, and the window occupancy rate Ku of the magnetic ring in the inductor.

3. The low-loss inductor design method of claim 1, wherein, In the step S3, the total loss equation of the inductor is constructed with the number of turns of the coil and the input voltage of the coil as variables, which comprises: S31, constructing a copper loss equation of the inductor according to a current effective value equation when the inductor works; S32, constructing an iron loss equation of the inductor according to the loss of the magnetic ring under alternating current magnetic induction intensity; S33, constructing a total loss equation of the inductor according to the copper loss equation of the inductor and the iron loss equation of the inductor.

4. The low-loss inductor design method of claim 1, wherein, In step S4, the target number of turns of the coil of the inductor is confirmed based on the total loss equation and the maximum input voltage corresponding to the inductor application scenario, which comprises: setting the input voltage of the coil in the total loss equation as the current maximum input voltage of the coil, and obtaining the number of turns of the coil with the minimum total loss as the target number of turns of the coil of the inductor.

5. The low-loss inductor design method of claim 1, wherein, The method further comprises: confirming the number of strands of the coil in parallel according to the diameter of the coil material and the diameter of the coil of the inductor.

6. The low-loss inductor design method of claim 1, wherein, In the step S7, the magnetic induction intensity of the inductor and the inductance of the inductor are obtained based on the initial design result, and it is confirmed whether the magnetic induction intensity and the inductance both meet the design requirements, which comprises: obtaining the maximum magnetic induction intensity of the magnetic ring in the working process of the inductor, and determining that the magnetic induction intensity meets the design requirements when the maximum magnetic induction intensity of the magnetic ring is less than a first preset value; obtaining the inductance of the inductor at the maximum input voltage according to an inductance equation and a direct current bias curve, and determining that the inductance meets the design requirements when the inductance is greater than a second preset value.

7. The low-loss inductor design method of claim 6, wherein, The reselected magnetic ring further comprises: When the magnetic induction intensity does not meet the design requirement, a magnetic material with a greater saturation magnetic induction intensity is replaced or a large-size magnetic ring is replaced.

8. The low-loss inductor design method of claim 6, wherein, The reselected magnetic ring includes: When the inductance does not meet the design requirement, a large-size magnetic ring is replaced or a magnetic material with a higher direct current bias resistance is replaced.

9. The low-loss inductor design method of claim 1, wherein, The method further includes: An absolute temperature of the inductance at the highest ambient temperature is obtained, and when the absolute temperature exceeds a third preset value, a magnetic material with a lower magnetic loss is selected or a large-size magnetic ring is replaced and the step S3 is performed.

10. An electronic device, comprising: The electronic device includes modules for performing the method of any one of claims 1 to 9.

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