Broadband multi-voltage dry-type isolation transformer for diesel storage system and operation method

Abstract

The invention relates to the technical field of isolation transformers, in particular to a dual-frequency six-in-one dry-type isolation transformer for a diesel storage system and an operation method, the dual-frequency six-in-one dry-type isolation transformer comprises a primary side coil and a secondary side coil which are wound outside an iron core, and the number of turns of the primary side coil and the number of turns of the secondary side coil are fixed; according to the invention, a single transformer can be compatible with six scenes of 50Hz / 60Hz dual-frequency and 380V / 400V / 420V three-voltage combination through fixing the number of turns of the coil and optimizing the flux density and current density design. According to the invention, the number of purchased transformers is reduced, the equipment cost and the installation cost are reduced, the installation space required by a plurality of devices is saved, the production cycle of a single device is far shorter than the cumulative cycle of six devices, and the deployment demand of a diesel storage system can be quickly responded.

Description

Technical Field

[0001] This invention relates to the field of isolation transformer technology, and in particular to a wide-frequency multi-voltage dry-type isolation transformer for diesel storage systems and its operating method. Background Technology

[0002] In integrated diesel generator-storage systems in the Asia-Pacific region, the voltage requirements of electrical equipment loads are concentrated in the 380V–420V range, and they need to be compatible with both 50Hz and 60Hz frequencies, forming a total of six usage scenarios: "3 voltages + 2 frequencies". Current technology requires a separate dry-type isolation transformer for each scenario. Specifically, six transformers with different parameters need to be manufactured, including SCB-630kVA / 0.42kV / 0.42kV, SCB-630kVA / 0.40kV / 0.40kV, and SCB-630kVA / 0.38kV / 0.38kV transformers compatible with 60Hz frequency, and three transformers of the same specifications compatible with 50Hz frequency. All transformers use the Dyn11 connection group.

[0003] This approach has significant drawbacks: Firstly, the procurement and installation of multiple transformers require a large amount of space and cost, and the production cycle is long, making it difficult to quickly respond to the deployment needs of the diesel-storage system. Secondly, some improved solutions attempt to set multiple sets of taps on the primary and secondary coils of a single transformer, and achieve the adaptation of different voltages and frequencies by manually switching the tap copper busbars. However, tap switching requires power outage operation, which not only affects the continuous power supply stability of the diesel-storage system, but also increases the cost of manual operation and the risk of wiring errors.

[0004] Furthermore, the core magnetic flux density design of traditional transformers is mostly based on a single frequency and a single voltage. If forced to adapt to dual-frequency and multi-voltage scenarios, problems such as magnetic flux density exceeding the 1.7T safety threshold and coil temperature rise exceeding the 100K standard for F-class products can easily occur. This leads to increased no-load losses and noise in the transformer, and long-term operation may even cause core overheating and insulation damage, shortening the equipment's lifespan. Therefore, improvements are needed. Summary of the Invention

[0005] In this section, as well as in the abstract and title of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this section, the abstract, and the title of this application, and such simplifications or omissions shall not be used to limit the scope of the invention.

[0006] To address the shortcomings of existing technologies that require multiple transformers, affect power supply due to tap switching, and are prone to excessive magnetic flux density and temperature rise under dual-frequency and multi-voltage operating conditions, one objective of this invention is to provide a wide-frequency multi-voltage dry-type isolation transformer for diesel storage systems.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a wide-frequency multi-voltage dry-type isolation transformer for a diesel storage system, comprising a primary winding and a secondary winding wound around the outside of an iron core, wherein both the primary winding and the secondary winding have a fixed number of turns, and the induced electromotive force per turn is expressed as... , in, It is the magnetic flux density of the iron core. It is the cross-sectional area of ​​the iron core. For frequency, These are fixed correction factors for the power frequency sine wave waveform coefficient and the core filling coefficient. The input voltage of the primary winding is... The output voltage of the secondary coil. The number of turns of the primary coil. This refers to the number of turns in the secondary coil. Among them, the magnetic flux density of the iron core for The cross-sectional area of ​​the iron core satisfy: .

[0008] As a preferred embodiment of the broadband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, wherein: the frequency The frequency is 50Hz, and the magnetic flux density of the iron core is 1.491~1.648T.

[0009] As a preferred embodiment of the broadband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, wherein: the frequency The frequency is 60Hz, and the magnetic flux density of the iron core is 1.308~1.665T.

[0010] As a preferred embodiment of the broadband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, wherein: the frequency The frequency is 50Hz. and The voltage is 380~400V, and the magnetic flux density of the iron core is 1.491~1.585T.

[0011] As a preferred embodiment of the broadband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, wherein: the frequency The frequency is 50Hz. and The voltage is 400~420V, and the magnetic flux density of the iron core is 1.585~1.648T.

[0012] As a preferred embodiment of the broadband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, wherein: the frequency The frequency is 60Hz. and The voltage is 380~400V, and the magnetic flux density of the iron core is 1.308~1.462T.

[0013] In a preferred embodiment of the broadband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, the secondary winding has multiple turns and is wound with copper foil, and the temperature rise of the secondary winding is... for The cross-sectional area of ​​the copper foil satisfies: , in, To sum the values ​​of segments from 1 to j, This refers to the resistance loss of the secondary coil. For the stray losses of the secondary coil, Let the mass of the secondary coil of segment j be... denoted as the total mass of the copper portion of the secondary winding, and 0.3 as an empirical correction factor for the heat dissipation characteristics of the dry-type transformer. This is the cross-sectional area of ​​the copper foil used in the secondary coil.

[0014] As a preferred embodiment of the broadband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, wherein: the number of turns of the secondary winding... It is configured as three segments. The three-section turns ratio satisfies: , Among them, when It has 33 turns. When the number of turns is 19, the turns ratio of the three sections satisfies: , in, The number of turns in the first section of the secondary side coil. The number of turns in the second section of the secondary side coil. The number of turns in the third segment of the secondary coil.

[0015] The advantages of this invention's wideband multi-voltage dry-type isolation transformer for diesel storage systems are as follows: By using a "fixed coil turns + optimized magnetic and electrical density design," a single transformer can be compatible with six scenarios involving dual frequencies of 50Hz / 60Hz and three voltage combinations of 380V / 400V / 420V, directly replacing six transformers in traditional solutions. This not only reduces the number of transformers required, lowering equipment and installation costs, but also saves installation space needed for multiple units. Furthermore, the production cycle of a single unit is significantly shorter than the cumulative cycle of six units, enabling rapid response to the deployment needs of diesel storage systems.

[0016] To address the shortcomings of existing technologies that require multiple transformers, affect power supply due to tap switching, and are prone to excessive magnetic flux density and temperature rise under dual-frequency and multi-voltage conditions, another objective of this invention is to provide an operation method for a dual-frequency six-in-one dry-type isolation transformer used in diesel storage systems.

[0017] To achieve the above objectives, the present invention adopts the following technical solution: an operation method for a wide-frequency multi-voltage dry-type isolation transformer for a diesel-storage system, wherein the primary winding is connected to the output terminal of the PCS of the diesel-storage system in a delta connection, and the secondary winding is connected to the load of the electrical equipment in a star connection with a neutral line led out, ensuring that the connection group of the primary and secondary sides remains unchanged at Dyn11; according to the power supply requirements of the load of the electrical equipment, the target power supply parameters are set through the PCS of the diesel-storage system; the PCS system is started to output the corresponding electrical energy to the primary winding according to the set power supply parameters; the secondary winding automatically outputs electrical energy corresponding to the frequency and voltage of the primary winding, providing a stable power supply to the load of the electrical equipment.

[0018] As a preferred embodiment of the operation method of the wideband multi-voltage dry-type isolation transformer for the diesel storage system described in this invention, the power supply parameters include frequency parameters and voltage parameters, wherein the frequency parameters are configured to be 50 or 60 Hz, and the voltage parameters are configured to be any one of 380V, 400V, and 420V.

[0019] The beneficial effects of the operation method of the wideband multi-voltage dry-type isolation transformer for diesel storage system of the present invention are the same as those of the wideband multi-voltage dry-type isolation transformer for diesel storage system, and will not be repeated here. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0022] Figure 2 This is a cross-sectional view of the entire invention.

[0023] Figure 3 This is a plan view of the entire invention.

[0024] Figure 4 This is a schematic diagram of the connection method between the primary and secondary sides of the present invention.

[0025] Figure 5This is a schematic diagram of the transformer structure in Scheme 2 of the present invention.

[0026] Figure 6 This is a plan view of the transformer in Scheme 2 of the present invention. Detailed Implementation

[0027] To make the objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0030] Example 1

[0031] In a system consisting of a DC battery compartment, PCS, transformer, and user equipment load, the primary and secondary voltages change simultaneously at a frequency of 60Hz. This differs from scenarios where adjusting the primary tap position keeps the secondary voltage constant.

[0032] For overseas 60Hz power grids and electrical equipment, SCB-630KVA / 400V / 400V is the rated voltage ratio, SCB-630KVA / 420V / 420V is the voltage ratio for stepping up the voltage, and SCB-630KVA / 380V / 380V is the voltage ratio for stepping down the voltage. Based on the three different voltages required by the secondary side user equipment, transformers with three different voltage ratios are needed.

[0033] The electrical load requires three secondary voltages U2: U21 (420V), U22 (400V), and U23 (380V) to power different electrical devices. The PCS system can input the required three primary voltages U11 (420V), U12 (400V), and U13 (380V) to power the transformer input terminal.

[0034] Existing technologies typically employ the following two methods to address this: 1. When the transformer needs to be used in a 60Hz environment, three transformers will be manufactured according to three voltage ratios (SCB-630kVA / 0.42kV / 0.42kV, SCB-630kVA / 0.4kV / 0.4kV, SCB-630kVA / 0.38kV / 0.38kV), and the corresponding transformer will be manufactured according to the actual voltage ratio of the power consumption.

[0035] Therefore, to meet the usage requirements of six different voltage and frequency combinations, the traditional approach is to design and manufacture six independent dry-type isolation transformers, specifically including: three voltage ratios at 60Hz: SCB-630kVA / 0.42kV / 0.42kV, SCB-630kVA / 0.40kV / 0.40kV, and SCB-630kVA / 0.38kV / 0.38kV; and three voltage ratios at 50Hz: SCB-630kVA / 0.42kV / 0.42kV, SCB-630kVA / 0.40kV / 0.40kV, and SCB-630kVA / 0.38kV / 0.38kV.

[0036] All transformers use the Dyn11 connection group, with a D connection on the primary side and a star (y) connection on the secondary side, and a neutral point (n) is provided. Each transformer is only suitable for a specific voltage and frequency combination and cannot be used interchangeably.

[0037] The above solution has the following drawbacks: it requires a large number of devices, resulting in high costs for procurement, warehousing, installation, and maintenance; it occupies a large space and is not suitable for compact diesel storage systems; and it has a long production cycle, making it difficult to respond quickly to project needs.

[0038] II. To solve the problem of multiple transformers, multiple sets of taps are set on the primary and secondary coils 102102 of a single transformer, and the different voltage ratios are adapted by manually switching the connecting copper busbars.

[0039] By connecting different tap combinations through an external copper busbar, three voltage ratios (420V / 420V, 400V / 400V, 380V / 380V) can be achieved.

[0040] Figures 5-6 The diagram above shows the structure of the second scheme. This scheme attempts to replace multiple transformers with fixed parameters with one transformer by setting multiple sets of taps on the primary winding 101 and secondary winding 102 of a single transformer.

[0041] As attached Figures 5-6 As shown, the transformer includes the following core components and wiring method: iron core 103, which serves as the main body of the magnetic circuit, on which both the primary coil 101 and the secondary coil 102 are wound.

[0042] Primary coil 101: adopts D connection and has three taps, which are led out to the terminal block through copper busbars respectively. They are defined as follows: tap N11: corresponding to 420V input voltage, tap N12: corresponding to 400V input voltage (rated range), tap N13: corresponding to 380V input voltage.

[0043] Secondary coil 102: It adopts a Y-connection and leads out a neutral point. It also has three taps, which are led out to the terminal block through copper busbars. They are defined as follows: Tap N21: corresponding to 380V output voltage, Tap N22: corresponding to 400V output voltage (rated range), Tap N23: corresponding to 420V output voltage.

[0044] Connection group: Internally, Dyn11 connection group is formed through fixed connections.

[0045] The use of this scheme relies entirely on manual physical connection switching that requires a power outage to achieve different voltage conversion ratios.

[0046] The standard operating procedure is as follows: Step 1: Completely disconnect the electrical connection between the transformer and the front-end PCS and the downstream electrical equipment load to ensure operational safety. Based on the current power supply requirements (e.g., 420V / 420V conversion at 60Hz), determine the required primary and secondary tap combinations. The corresponding relationships are as follows: Target 420V / 420V: Primary side connects to N11, secondary side connects to N21; Target 400V / 400V: Primary side connects to N12, secondary side connects to N22; Target 380V / 380V: Primary side connects to N13, secondary side connects to N23.

[0047] Step 2: Using specialized tools, disconnect all copper busbars currently connected to the primary and secondary side terminals; connect the three input lines from the PCS system to the primary side target tap terminal (e.g., for 420V input, connect to terminal N11); connect the three output lines leading to the electrical equipment load to the secondary side target tap terminal (e.g., for 420V output, connect to terminal N21); carefully check all connections to ensure they are secure, not loose, and restore necessary insulation.

[0048] Step 3: After confirming that all wiring is correct, restore the system power supply; use a multimeter or other measuring instruments to verify the output voltage at the output terminal of the transformer secondary side, and confirm that it is stable at the target voltage value (such as 420V), and complete the switching operation.

[0049] Specifically, if the transformer needs to be used at 60Hz, and different voltage ratios U1 / U2 (primary coil voltage 101101 / secondary coil voltage) are required, copper busbars need to be drawn according to the corresponding number of tap turns (420 / 420V corresponding to tap turns N11 / N21, 400 / 400V corresponding to tap turns N12 / N22, 380 / 380V corresponding to tap turns N13 / N23). The primary and secondary connection copper busbars corresponding to the three different voltages can be manually replaced.

[0050] In summary, although this solution physically achieves "multi-purpose functionality," it suffers from the following insurmountable drawbacks, which are precisely the problems this invention aims to completely solve: Power supply continuity interruption: Each tap switching operation requires a power outage, causing the diesel storage system to lose continuous power supply, severely impacting critical loads reliant on continuous power supply; Cumbersome operation and high safety risks: The entire process involves multiple steps such as power outage, disconnection, connection, and power restoration, requiring high levels of professional skills from operators. The complex process makes wiring errors highly likely, potentially leading to short circuits, burnout, or even personal injury accidents; High manufacturing and maintenance costs: Multiple taps, complex internal connections, and a large number of copper busbars significantly increase the transformer's raw material costs, process complexity, and manufacturing costs. Furthermore, exposed connection points and switching components increase potential failure points, resulting in high maintenance costs; Performance design compromises: To ensure barely operable operation at several voltage ratios, the transformer's electromagnetic parameters (such as core magnetic flux density 103 and coil current density) must be compromised, making it difficult to achieve optimal performance under all operating conditions. This may lead to increased no-load losses, reduced efficiency, and critical temperature rise in some tap positions of the transformer, affecting its lifespan and reliability.

[0051] Therefore, this scheme has significant shortcomings in terms of operability, safety, and economy due to its reliance on manual operation and the need for a power outage to switch taps, and cannot meet the requirements of modern diesel storage systems for efficient, continuous, and reliable operation.

[0052] Example 2

[0053] Reference Figure 1 and Figure 4 This embodiment provides a wideband multi-voltage dry-type isolation transformer for diesel storage systems. This transformer addresses the power demand of six scenarios in diesel storage systems, including wideband (50Hz and 60Hz) and multi-voltage (380V, 400V, 420V). By optimizing the cross-sectional area of ​​the 103 core, fixing the number of coil turns, and the three-stage distribution design, it ensures that the temperature rise and magnetic flux density are within the limited range while achieving precise adaptation of core parameters and maximizing performance.

[0054] The transformer of the present invention is a three-phase dry-type transformer, whose core 103 is usually a three-column structure, and three sets of windings are respectively wound on three columns of the core 103. The windings include a primary coil 101 and a secondary coil 102.

[0055] The first end of each primary coil 101 is directly and rigidly connected to the end of the adjacent coil through a copper busbar, forming a closed triangular circuit. The copper busbar connection is fastened with bolts, and flat washers and spring washers are added at the connection to ensure the mechanical strength and electrical contact reliability of the connection, and to avoid excessive contact resistance that could lead to localized heating.

[0056] Each secondary coil 102 has an output copper busbar leading out from its start end, for a total of three phases; the ends of the three coils are rigidly connected by a common copper busbar to form a neutral node in a star connection.

[0057] like Figure 4 As shown in (a), each winding has two clearly defined terminals, and the three windings have a total of six terminals, namely: A and X, B and Y, and C and Z.

[0058] Implementation of D-connection (delta connection): The above six terminals are connected in a "head-to-tail" manner to form a closed delta circuit through the D-connection copper busbar.

[0059] The specific connection relationships are as follows: the end X of winding A is connected to the beginning B of winding B through a copper busbar; the end Y of winding B is connected to the beginning C of winding C through a copper busbar; and the end Z of winding C is connected to the beginning A of winding A through a copper busbar.

[0060] Finally, from these three connection points (A / Z, B / X, C / Y), three perforated copper busbars are led out to the three primary-side input terminals on the transformer casing. These three input terminals correspond to phases A, B, and C of the three-phase power supply, respectively, and are used to connect to the three-phase output terminals of the PCS (energy storage converter) of the diesel-storage system.

[0061] The secondary coil 102 also consists of three independent windings.

[0062] like Figure 4 As shown in (b), each winding also has two terminals: A and X, B and Y, and C and Z. Additionally, there is a neutral point 0.

[0063] The implementation of the Y-connection (star connection) and neutral point: The ends X, Y, and Z of the three secondary windings are connected to a common point, which is the neutral point 0. A neutral point busbar is then used to connect the neutral point to the neutral point terminal (marked as "0" or "N") on the transformer casing. The beginning ends A, B, and C of the three windings are directly connected to the secondary output terminal on the transformer casing via an output busbar.

[0064] Specifically, the secondary output terminals (A, B, C) and the neutral point terminal (0) are connected together to the load of the electrical equipment to provide a three-phase four-wire power supply to the load.

[0065] The fixed connection method of the primary side coil 101D and the secondary side coil 102y together constitutes the Dyn11 connection group.

[0066] It is important to note that all internal connecting copper busbars (including D-connecting copper busbars and neutral point connecting copper busbars) and external lead-out copper busbars are reliably electrically isolated and mechanically fixed by insulators to ensure safe operation.

[0067] Example 3

[0068] This embodiment provides a wideband multi-voltage dry-type isolation transformer for a diesel storage system, including a primary winding 101 and a secondary winding 102, both with a fixed number of turns, and the induced electromotive force per turn is expressed as follows: , in, It has a 103 magnetic flux density core. It is the cross-sectional area of ​​the iron core 103. For frequency, These are fixed correction factors for the power frequency sine wave waveform coefficient and the core 103 filling coefficient. The input voltage of the primary coil 101, The output voltage of the secondary coil 102, The primary winding has 101 turns. The secondary coil has 102 turns; the core has a magnetic flux density of 103. for Cross-sectional area of ​​iron core 103 satisfy: , Among them, the power frequency sine wave waveform coefficient is 4.44, and the core filling coefficient is 0.95. This is the frequency correction factor.

[0069] The following is the derivation process of the cross-sectional area of ​​the 103 iron core: Based on the above formula for the induced electromotive force per turn, the formula for the cross-sectional area of ​​the iron core 103 is as follows: , Since the unit of magnetic flux density B is T (Tesla), the corresponding unit of the cross-sectional area A of the iron core is... (square meters), therefore, the above formula for the cross-sectional area of ​​the iron core 103 needs to be standardized through unit conversion to obtain the correct dimensions. , Will 60Hz 400V It has 33 turns. It has 19 turns. for , Substituting 375 into the formula for the cross-sectional area of ​​the iron core 103 above, we get... , The following is the magnetic flux density verification process for iron core 103: Based on the above formula for the induced electromotive force per turn, the formula for the magnetic flux density of the 103 core is obtained as follows: , Will For 50Hz, 400V It has 33 turns. It has 19 turns. It is 450. for Substituting into the formula for the cross-sectional area of ​​the magnetic flux density of the iron core 103, we get , Will For 50Hz, 380V It has 33 turns. It has 19 turns. It is 450. for Substituting into the formula for the cross-sectional area of ​​the magnetic flux density of the iron core 103, we get , Will For 50Hz, It is 420V. It has 33 turns. It has 19 turns. It is 450. for Substituting into the formula for the cross-sectional area of ​​the magnetic flux density of the iron core 103, we get , Will For 60Hz, It is 380V. It has 33 turns. It has 19 turns. It is 450. for Substituting into the formula for the cross-sectional area of ​​the magnetic flux density of the iron core 103, we get , Will For 60Hz, It is 420V. It has 33 turns. It has 19 turns. It is 450. for Substituting into the formula for the cross-sectional area of ​​the magnetic flux density of the iron core 103, we get , therefore, 50Hz or 60Hz and For any of the following scenarios: 380V, 400V, or 420V for , for .

[0070] Specifically, the magnetic flux density B is determined by three factors: the material properties of the core 103, industry standards, and operational safety. Transformer core 103 commonly uses high-silicon steel sheets (such as 30Q130), whose saturation magnetic flux density is approximately 1.7–1.8T. When B exceeds the saturation magnetic flux density, the permeability of the core 103 drops sharply, leading to a surge in no-load current (potentially increasing more than 10 times), a sharp increase in no-load losses, overheating of the core 103, increased noise, and even insulation burnout. Therefore, the industry default is that the magnetic flux density should be lower than the saturation magnetic flux density, typically leaving a safety margin of 5%–10%.

[0071] If the magnetic flux density B is too low, the cross-sectional area A of the iron core 103 needs to be increased significantly, which increases the amount of material used in the iron core 103, resulting in higher costs and larger volume; if the magnetic flux density B is too high, it will approach the saturation region, which will greatly increase the risk.

[0072] In summary, based on the rated operating condition of 400V / 400V (60Hz), the magnetic flux density B is 1.308T, which ensures that: at 60Hz, the magnetic flux density B is 1.566T for 380V and 1.665T for 420V (both < 1.7T); at 50Hz, the magnetic flux density B is 1.491T for 380V, 1.570T for 400V, and 1.648T for 420V (all < 1.7T), achieving safe magnetic flux density coverage across all operating conditions.

[0073] If the goal is to achieve the "maximum magnetic flux density within a safe range" (e.g., a reference magnetic flux density of 1.6T), even under 60Hz / 420V operating conditions ( It is temporarily safe, but the magnetic flux density will increase to [a certain value] under 50Hz / 420V operating conditions. (far exceeding the 1.7T safety threshold), resulting in core 103 saturation and a surge in no-load losses.

[0074] If the benchmark magnetic flux density is further reduced from 1.308T (e.g., to 1.2T), the risk of exceeding the magnetic flux density limit can be further reduced, but this will lead to three major problems: increased material costs, larger equipment size, and decreased economic efficiency, as detailed below: 1) The cross-sectional area of ​​the 103 iron core was forced to increase, leading to higher material costs: According to the formula In terms of voltage U, number of turns N, and frequency correction factor When fixed, the magnetic flux density B is inversely proportional to the cross-sectional area A of the iron core 103. If B decreases from 1.308T to 1.2T, the cross-sectional area of ​​the iron core 103 needs to increase from 348.43cm² to... The use of silicon steel sheets increased by about 8.7%, which directly led to an increase in the procurement cost of iron core 103.

[0075] 2) Increased equipment size and increased installation space: The increased cross-sectional area of ​​the iron core 103 will inevitably lead to an increase in the overall size of the transformer (especially the height and width of the iron core 103), which contradicts the core objective of this solution to "replace 6 transformers and save installation space" and cannot meet the deployment requirements of a compact diesel storage system.

[0076] 3) Although the no-load loss is reduced, the economic balance is unbalanced: The reduction in magnetic flux density will slightly reduce the no-load loss (hysteresis loss + eddy current loss) of the iron core 103 (about 5% to 8%), but the saved operating loss cost is far from enough to offset the increased procurement cost of the iron core 103 material, and the equipment manufacturing cycle is extended (the processing of large cross-sectional area iron core 103 is more difficult), resulting in a significant decrease in overall economic efficiency.

[0077] Therefore, the magnetic flux density of the iron core 103 for It represents the optimal balance between "cost and safety." It achieves a magnetic flux density below the saturation threshold of 1.7T (leaving ample safety margin) while simultaneously reducing the cross-sectional area of ​​the 103 core through higher magnetic flux density, thus controlling the transformer's size and cost. This ensures that the magnetic flux density remains within acceptable limits across all voltage levels (50Hz / 60Hz, 400V / 380V / 420V) while avoiding uncontrolled increases in the size and cost of the 103 core due to excessively low magnetic flux density.

[0078] In summary, when the transformer operates under all six target scenarios (3 voltages + 2 frequencies), the magnetic flux density of the core 103 remains below the safe threshold (i.e., 1.7T), effectively avoiding a series of problems caused by excessive magnetic flux density, such as a surge in no-load loss, increased no-load current, increased noise, and overheating of the core 103, thus ensuring the long-term operating life and efficiency of the transformer.

[0079] Example 4

[0080] This embodiment provides a wideband multi-voltage dry-type isolation transformer for a diesel storage system, including a secondary coil 102 with multiple turns configured and wound with copper foil, and a temperature rise of the secondary coil 102. for The cross-sectional area of ​​the copper foil satisfies: , in, To sum the values ​​of segments from 1 to j, For the resistance loss of the secondary coil 102, For the stray loss of the secondary coil 102, Let the mass of the j-th secondary side coil 102 be... denoted as , where is the total mass of the copper portion of the secondary winding 102, and 0.3 is an empirical correction factor for the heat dissipation characteristics of the dry-type transformer. This is the cross-sectional area of ​​the copper foil used in the secondary coil 102.

[0081] Furthermore, the secondary coil has 102 turns. It is configured as three segments. The three-section turns ratio satisfies: , Among them, when It has 33 turns. When the number of turns is 19, the turns ratio of the three sections satisfies: , in, The number of turns in the first section of the secondary coil 102. This refers to the number of turns in the second section of the secondary coil 102. This refers to the number of turns in the third section of the secondary coil 102.

[0082] Preferably, when It has 33 turns. When it is 19 turns, ,in: It has 6 turns. It is 5.5 turns. It is 7.5 turns.

[0083] Fixed parameters: The transformer capacity is 630kVA (standard load of the diesel-storage system, determining the basic requirements for current carrying capacity); the primary winding 101 has 33 turns and adopts a D connection (i.e., delta connection, therefore line voltage = phase voltage); the secondary winding 102 has 19 turns and adopts a Y connection (i.e., star connection, therefore line voltage = √3 × phase voltage), and is wound in 3 sections (6 turns + 5.5 turns + 7.5 turns); the cross-sectional area A of the core 103 is 348.43cm², and the magnetic flux density B under all operating conditions is <1.7T (dual-frequency compatible core magnetic circuit design to avoid overheating of the core 103).

[0084] Since the secondary coil 102 is directly connected to the load of the electrical equipment, it needs to be compatible with six operating conditions, including three voltages (380V, 400V, and 420V) and two frequencies (50Hz and 60Hz). Due to the influence of the turns ratio (33:19) and the Dyn11 connection group, the secondary side line current is much greater than that of the primary side. Its resistance loss and stray loss account for 70% to 80% of the total coil loss, which is the core constraint for temperature rise control. On the other hand, the primary side current is small and the loss is low. Moreover, the coil design naturally has a lower current density and better heat dissipation conditions. Its temperature rise is far below the F-class insulation standard of 100K and will not become a risk point for excessive temperature rise.

[0085] Therefore, in engineering design, the principle of "focusing on the main contradiction" is followed. As long as the secondary current is calculated and the copper foil area is matched to meet its temperature rise requirements, the operation of the entire transformer can be ensured to be compliant, without the need to calculate the relevant parameters of the primary side.

[0086] The following is the derivation process of the copper foil area: Capacity formula based on three-phase transformer , Since the secondary side is a Y-connection. (The core electrical characteristics of the Y-connection), therefore the current calculation formula can be simplified to: , in, This is the secondary side line voltage. For secondary side line current, This refers to the transformer capacity.

[0087] Will for , Substituting 380V into the above current formula, we get , Will for , Substituting 400V into the above current formula, we get , Will for , Substituting 420V into the above current formula, we get , In conclusion, The smaller, The larger the voltage, and the higher the maximum current among the three voltages (380V, 400V, 420V). (i.e., 380V / 380V operating conditions).

[0088] Since current density (current carried per unit area) directly determines the "resistive loss" and "temperature rise" of copper foil, based on the formulas for current density and resistance loss, the current density formula is: , in, For current density, For phase current, This represents the cross-sectional area of ​​the copper foil.

[0089] The formula for resistance loss is: , in, For resistive loss, For phase current, For resistance, The resistivity of copper, This represents the winding length.

[0090] According to industry standards, the long-term permissible current density for copper foil used in dry-type transformers is [insert value here]. (Class F insulation, mandatory standard at an ambient temperature of 40°C).

[0091] Based on the above current density formula, we obtain... , in, The minimum total area of ​​the secondary copper foil must be able to carry the maximum phase current. .

[0092] Will for , Substituting into the above formula, we get , Therefore, the total area of ​​the copper foil needs to be ≥797.5mm² to meet the current carrying requirements of 380V operating conditions and avoid exceeding the current density limit.

[0093] Specifications of copper foil: 1. Since the thickness of copper foil in dry-type transformers is usually 0.8~1.0mm (too thin: easy to deform and break during winding; too thick: severe "skin effect" at 60Hz frequency, current concentrated on the surface, increasing additional losses); therefore, the thickness parameter of copper foil is preferably selected as 0.9mm (balancing mechanical strength and skin effect: the skin depth of copper at 60Hz is ≈8.6mm, and the thickness of 0.9mm is much smaller than the skin depth, resulting in uniform current distribution).

[0094] Second, since the dry-type transformer used in this invention is a 630kVA-class low-voltage dry-type transformer with an input and output voltage of 380V~420V, the conventional design range for the core 103 window width in the industry is 480mm~520mm. If the core 103 window width is too small, it cannot accommodate a sufficient number of coil turns, which will lead to winding interference, increased leakage flux, and increased stray losses. If the core 103 window width is too large, the volume and weight of the core 103 will increase dramatically, which contradicts the goal of this invention to "replace 6 transformers and save installation space," and will also increase material costs and production cycle.

[0095] Furthermore, based on the above, the cross-sectional area A of core 103 is 348.43 cm². There is a fixed structural matching relationship between the cross-sectional area of ​​core 103 and the window size of core 103: the transformer core 103 is usually "laminated", consisting of "core 103 column" and "yoke". The window width needs to be designed in coordination with the cross-sectional areas of core 103 column and yoke to ensure uniform magnetic flux transmission. For a 630kVA transformer, the cross-sectional area of ​​the yoke corresponding to the 348.43 cm² core 103 cross-sectional area (core 103 column) is approximately 313.5 cm² (the yoke cross-sectional area is usually 0.9 times that of core 103 column). Combined with magnetic circuit calculations, the window width needs to be ≥490 mm to ensure reasonable magnetic reluctance and avoid local magnetic flux exceeding the standard.

[0096] The copper foil itself is set to a width of 490mm, and an insulation gap of 5mm is reserved on each side (totaling 10mm). Therefore, the overall width of the coil is about 500mm. The window width of the iron core 103 needs to be slightly larger than the width occupied by the coil in order to avoid scratches caused by friction between the copper foil and the edge of the iron core 103 during winding. In accordance with the industry design convention that "the window width is 5~10mm larger than the maximum width of the coil", the window width needs to be ≥500mm.

[0097] Therefore, the specifications for copper foil are set at 0.9mm (thickness) × 490mm (width).

[0098] Based on the formula for calculating the area of ​​copper foil, we obtain , From the above, we can see that the area of ​​the copper foil is... Therefore, it does not meet the minimum area requirement of copper foil, and the current density is 957 / 441≈2.17A / mm²>1.2A / mm², which will cause the temperature rise to exceed the standard.

[0099] If the above The copper foil is designed to be double-layered, with a total area of ​​[area missing]. Therefore, it meets the minimum area requirement of copper foil, and the current density is 957 / 882≈1.08A / mm², which is within the optimal range of 1.0~1.2A / mm². In addition, setting the copper foil to a double-layer structure can further optimize the skin effect (the total thickness of the double layer is still <8.6mm at 1.8mm), and double the heat dissipation area, reducing the risk of local overheating.

[0100] The following is the temperature rise verification process: Based on the temperature rise formula , in, The temperature rise due to losses in the j-th segment of the secondary coil 102, For the corrected temperature rise of the secondary coil 102 of the j-th segment, The weight of the secondary coil 102 of the j-th segment is given.

[0101] When the frequency is 60Hz and the voltage is 380V, the parameters of the three-section secondary coil 102 are as follows: Section 1: 6 turns, resistance loss is 660W, stray loss is 45W, and temperature rise due to loss. The corrected temperature rise is 95.1 kJ. It weighs 3.2k. It weighs 50.9 kg.

[0102] Section 2: 5.5 turns, resistive loss is 704W, stray loss is 49W, and temperature rise due to loss. The corrected temperature rise is 96.9 K. It is 2.2k and weighs It weighs 54.4 kg.

[0103] Section 3: 7.5 turns, resistance loss is 1102W, stray loss is 76W, and temperature rise due to loss. The corrected temperature rise is 101.1 K. It weighs 4.2k. It weighs 85.2 kg.

[0104] Substituting the above parameters into the temperature rise formula, we get... , , , Therefore, when the frequency is 60Hz, the voltage is 380V, and the copper foil area is At that time, the temperature rise of the secondary coil 102 It meets the F-level standard.

[0105] When the frequency is 60Hz and the voltage is 420V, the parameters of the three-section secondary coil 102 are as follows: Section 1: 6 turns, resistance loss is 605W, stray loss is 36W, and temperature rise due to loss. The corrected temperature rise is 85.8K. It is 2.9k and weighs It weighs 50.9 kg.

[0106] Section 2: 5.5 turns, resistive loss is 644W, stray loss is 39W, and temperature rise due to loss. The corrected temperature rise is 88.7 K. It is 2.0k and weighs 2.0k. It weighs 54.4 kg.

[0107] Section 3: 7.5 turns, resistance loss is 1102W, stray loss is 60W, and temperature rise due to loss. The corrected temperature rise is 90.5K. It weighs 3.9k. It weighs 85.2 kg.

[0108] Substituting the above parameters into the temperature rise formula, we get... , , , Therefore, when the frequency is 60Hz, the voltage is 420V, and the copper foil area is... At that time, the temperature rise of the secondary coil 102 is It meets the F-level standard.

[0109] There are six scenarios involving two frequencies (60Hz, 60Hz, 380V, 400V, and 420V), with 60Hz + 420V / 420V representing the lowest temperature rise and 60Hz + 380V / 380V representing the highest temperature rise. Based on the above derivation, the temperature rise of the secondary coil 102 at 60Hz + 420V / 420V is... for Temperature rise of secondary coil 102 at 60Hz +380V / 380V for Therefore, it can be seen that both the highest and lowest scene temperature rises are... It meets the F-level standard.

[0110] If the temperature rise is too low (<85.8K): the cross-sectional area of ​​the copper foil needs to be further increased (such as using three layers of 0.9×490mm copper foil) or the magnetic flux density of the iron core needs to be reduced. This will lead to an increase in the amount of copper and silicon steel sheets used, an increase in equipment cost of 15%~20%, and an increase in volume, which violates the design goal of "replacing 6 transformers and saving space".

[0111] If the temperature rise is too high (>98.3K): Although the cross-sectional area of ​​the copper foil can be reduced or the magnetic flux density can be increased, the material cost can be reduced in the short term, but it will approach the insulation limit of 100K. In the long term, excessive loss will easily lead to overheating of the iron core 103, increased noise, increased maintenance costs and failure risk.

[0112] Therefore, the temperature rise of the secondary coil 102 for It meets the F-class insulation safety requirements, is compatible with all 6 scenarios, controls material costs and equipment size, and ensures long-term operational stability. It is the optimal temperature rise range for the dual-frequency six-in-one transformer in the diesel-storage system.

[0113] Furthermore, the copper foil is selected with a width-to-thickness ratio of 0.9mm × 490mm to obtain a sufficiently large conductor cross-sectional area within a given current capacity, thereby reducing current density and fundamentally reducing resistance loss, which is a key measure for controlling temperature rise. The "double-layer structure" further optimizes the conductor's skin effect, improves current distribution, and enhances the mechanical strength and heat dissipation capacity of the winding. In addition, copper foil has advantages such as large heat dissipation area, strong short-circuit withstand capability, and high process consistency.

[0114] Furthermore, the secondary winding 102 is structurally divided into three sections: 6 turns, 5.5 turns, and 7.5 turns (a total of 19 turns). This segmented design is for process optimization, heat dissipation uniformity, and ampere-turn balance. It helps control leakage flux, reduce stray losses, and make the temperature rise distribution of the coil more uniform, avoiding local overheating, thereby improving the overall performance and reliability of the transformer.

[0115] In summary, through a series of interconnected and synergistic technical means—namely, a fixed turns ratio (33:19), a core cross-sectional area of ​​103 (348.43 cm²), a low reference magnetic flux density design (minimum 1.308 T), and low electrical flux density copper foil windings (0.9 × 490 mm double layer)—a single transformer can safely, stably, and efficiently cover six application scenarios with dual frequencies of 50Hz / 60Hz and three voltages of 380V / 400V / 420V without any external adjustments. This perfectly solves the problems of numerous devices, complex operation, and potential safety hazards in existing technologies.

[0116] Example 5

[0117] Reference Figure 1and Figure 4 This embodiment provides an operation method for a wideband multi-voltage dry-type isolation transformer for a diesel-storage system. The method includes connecting the primary winding 101 to the output terminal of the diesel-storage system's PCS using a delta connection, and connecting the secondary winding 102 to the load of the electrical equipment using a star connection with a neutral line led out, ensuring that the connection group of the primary and secondary sides remains unchanged at Dyn11. Based on the power supply requirements of the load of the electrical equipment, target power supply parameters are set through the PCS of the diesel-storage system. The PCS system is activated, causing it to output corresponding electrical energy to the primary winding 101 according to the set power supply parameters. The secondary winding 102 automatically outputs electrical energy corresponding to the frequency and voltage of the primary winding, providing a stable power supply to the load of the electrical equipment.

[0118] Furthermore, the power supply parameters include frequency parameters and voltage parameters. The frequency parameter is configured to be 50 or 60 Hz, and the voltage parameter is configured to be any one of 380V, 400V, or 420V.

[0119] During use, first, complete the electrical connection between the transformer and the diesel storage system and the electrical equipment. Connect the primary winding 101 of the transformer to the output terminal of the PCS (energy storage converter) of the diesel storage system through the three-phase terminal block, ensuring that the D connection of the primary winding 101 corresponds accurately to the three-phase line of the PCS output terminal. At the same time, connect the secondary winding 102 to the load of the electrical equipment through the connection structure with a neutral point, ensuring that the Y connection of the secondary winding 102 matches the three-phase four-wire power supply requirements of the load. All connection nodes must be securely fastened and properly insulated.

[0120] Then, based on the actual power consumption scenario, the parameters of the PCS are set through the control system of the diesel storage system, so that the PCS outputs voltage and frequency signals corresponding to the target scenario to the primary coil 101 of the transformer.

[0121] The target scenarios here cover the full combination of dual frequencies and three voltages, specifically including three voltage ratio scenarios at 60Hz: 420V / 420V, 400V / 400V, and 380V / 380V, as well as three voltage ratio scenarios at 50Hz: 420V / 420V, 400V / 400V, and 380V / 380V.

[0122] Finally, because the transformer adopts a fixed turns ratio (33 turns on the primary side and 19 turns on the secondary side) and an optimized core 103 design, after the target voltage and frequency output by the PCS are connected to the primary side, no manual switching of coil taps or adjustment of connection groups is required. The transformer can automatically achieve voltage conversion through the principle of electromagnetic induction, and output a stable voltage corresponding to the voltage and frequency of the primary side on the secondary side coil 102. This continuously provides the power supply that meets the needs of the electrical equipment load without interrupting the power supply, ensuring the continuity and reliability of the diesel storage system.

[0123] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A wideband multi-voltage dry-type isolation transformer for a diesel storage system, characterized in that: include, A primary coil (101) and a secondary coil (102) are wound around the outside of the iron core (103). Both the primary coil (101) and the secondary coil (102) have a fixed number of turns, and the induced electromotive force per turn is expressed as... ， in, It is the magnetic flux density of the iron core (103), It is the cross-sectional area of ​​the iron core (103). For frequency, For the fixed correction coefficients of the power frequency sine wave waveform coefficient and the iron core (103) filling coefficient, The input voltage of the primary winding (101) is... The output voltage of the secondary coil (102) is... The number of turns of the primary coil (101) The number of turns of the secondary coil (102); Among them, the magnetic flux density of the iron core (103) for The cross-sectional area of ​​the iron core (103) satisfy: 。 2. The broadband multi-voltage dry-type isolation transformer for diesel storage systems as described in claim 1, characterized in that: The frequency The frequency is 50Hz, and the magnetic flux density of the iron core (103) is 1.491~1.648T.

3. The broadband multi-voltage dry-type isolation transformer for diesel storage systems as described in claim 1, characterized in that: The frequency The frequency is 60Hz, and the magnetic flux density of the iron core (103) is 1.308~1.665T.

4. The wideband multi-voltage dry-type isolation transformer for diesel storage systems as described in claim 2, characterized in that: The frequency The frequency is 50Hz. and The voltage is 380~400V, and the magnetic flux density of the iron core (103) is 1.491~1.585T.

5. The wideband multi-voltage dry-type isolation transformer for diesel storage systems as described in claim 2, characterized in that: The frequency The frequency is 50Hz. and The voltage is 400~420V, and the magnetic flux density of the iron core (103) is 1.585~1.648T.

6. The wideband multi-voltage dry-type isolation transformer for diesel storage systems as described in claim 3, characterized in that: The frequency The frequency is 60Hz. and The voltage is 380~400V, and the magnetic flux density of the iron core (103) is 1.308~1.462T.

7. The broadband multi-voltage dry-type isolation transformer for diesel storage systems as described in any one of claims 1 to 6, characterized in that: The secondary coil (102) is wound in multiple segments and is wound with copper foil. The temperature rise of the secondary coil (102) for The cross-sectional area of ​​the copper foil satisfies: ， in, To sum the values ​​of segments from 1 to j, For the resistance loss of the secondary coil (102), For the stray loss of the secondary coil (102), Let the mass of the j-th secondary side coil (102) be... is the total mass of the copper portion of the secondary winding (102), and 0.3 is the empirical correction factor for the heat dissipation characteristics of the dry-type transformer. The cross-sectional area of ​​the copper foil used for the secondary coil (102).

8. The wideband multi-voltage dry-type isolation transformer for diesel storage systems as described in claim 7, characterized in that: The number of turns of the secondary coil (102) It is configured as three segments. The three-section turns ratio satisfies: ， Among them, when It has 33 turns. When the number of turns is 19, the turns ratio of the three sections satisfies: ， in, The number of turns in the first section of the secondary side coil (102) is... The number of turns of the second section of the secondary side coil (102) is... The number of turns in the third section of the secondary side coil (102) is given.

9. An operation method for a wideband multi-voltage dry-type isolation transformer for a diesel storage system, characterized in that: Connect the primary coil (101) to the PCS output terminal of the diesel storage system in a delta connection, and connect the secondary coil (102) to the load of the electrical equipment in a star connection and lead out the neutral line, so as to ensure that the connection group of the primary and secondary sides remains unchanged at Dyn11. Based on the power supply requirements of the electrical equipment load, the target power supply parameters are set through the PCS of the diesel storage system; Start the PCS system so that it outputs the corresponding electrical energy to the primary coil (101) according to the set power supply parameters. The secondary coil (102) automatically outputs electrical energy corresponding to the frequency and voltage of the primary side, providing a stable power supply for the load of the electrical equipment.

10. The operation method of the broadband multi-voltage dry-type isolation transformer for diesel storage system as described in claim 9, characterized in that: The power supply parameters include frequency parameters and voltage parameters. The frequency parameter is configured to be 50 or 60 Hz, and the voltage parameter is configured to be any one of 380V, 400V, or 420V.

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