Transformer, power conversion device, and medical instrument

Abstract

The application relates to a transformer, a power conversion device and a medical instrument, the transformer comprising: a primary winding; a plurality of magnetic core assemblies, the primary winding passing through the plurality of magnetic core assemblies; a plurality of secondary windings, the secondary windings being respectively wound on the magnetic core assemblies; wherein each of the magnetic core assemblies is provided with an air gap with the same size; and / or the transformer comprises a capacitor and an impedance element, the capacitor and the impedance element being connected in series, and the series-connected capacitor and impedance element being connected to two ends of a corresponding secondary winding. The method can solve the problem of uneven voltage of the secondary windings corresponding to the output of the transformer.

Description

Technical Field

[0001] This application relates to the field of transformers, and in particular to transformers, power conversion devices, and medical devices. Background Technology

[0002] High-voltage power supplies are widely used in fields such as medical X-ray generation, air pollution control, industrial testing, high-energy physics, and plasma applications, with high-voltage high-frequency transformers being their core component. However, conventional high-voltage high-frequency transformers with concentrated magnetic cores suffer from problems such as excessively high step-up ratios leading to large size, large parasitic capacitance in the windings, uneven voltage distribution within the windings, internal partial discharge, and difficulty in heat dissipation.

[0003] In traditional distributed high-voltage high-frequency transformers, the high-voltage side windings, i.e., the secondary windings, are wound on different magnetic cores. After rectification and filtering, they are connected in series to obtain a high-voltage DC output, while the primary winding passes through all the magnetic cores simultaneously. This type of multi-core distributed high-voltage transformer has a compact structure, good heat dissipation, and low winding parasitic capacitance, making it very suitable for high-voltage and high-frequency applications. However, when the characteristics of each magnetic core differ, such as inconsistent permeability or inconsistent core cross-sectional area, the output voltage of each high-voltage side winding will be inconsistent. In extreme cases, this may lead to local breakdown of the winding with excessively high voltage or overvoltage damage to the corresponding rectifier circuit. Summary of the Invention

[0004] Therefore, it is necessary to provide a transformer, power conversion device, and medical device that can solve the problem of uneven voltage in the secondary winding of a transformer, in response to the above-mentioned technical problems.

[0005] In a first aspect, this embodiment provides a transformer, the transformer comprising: a primary winding; a plurality of magnetic core assemblies, the primary winding passing through the plurality of magnetic core assemblies; and a plurality of secondary windings, the secondary windings respectively wound on each of the magnetic core assemblies; wherein,

[0006] Each of the magnetic core assemblies has an air gap of the same size; and / or,

[0007] The transformer includes a capacitor and an impedance element. The capacitor and the impedance element are connected in series, and the series-connected capacitor and impedance element are connected to the two ends of the corresponding secondary winding.

[0008] In some of these embodiments, the impedance element includes a resistor.

[0009] In some embodiments, the impedance element includes a resistor and an inductor connected in parallel.

[0010] In some of these embodiments, the impedance element includes an inductor.

[0011] In some embodiments, each of the magnetic core assemblies has an air gap of the same size; the transformer includes a capacitor, the two ends of which are connected to the two ends of the secondary winding.

[0012] In some embodiments, the transformer includes multiple rectifier circuits, each of which is connected to a secondary winding.

[0013] In some embodiments, the parameters of the impedance element are determined based on at least one of the following parameters: the frequency of the AC voltage input to the primary winding, the load range of the transformer, the characteristics of the core assembly, and the preset losses of the transformer.

[0014] Secondly, this embodiment provides a power conversion device, which includes an inverter circuit and the transformer described in the first aspect; wherein the inverter circuit is connected to the primary winding of the transformer.

[0015] In some embodiments, the inverter circuit includes a switching element; wherein the switching element adjusts the direction of current in the inverter circuit by changing its on / off state.

[0016] Thirdly, this embodiment provides a medical device including the transformer described in the first aspect.

[0017] The aforementioned transformers, power conversion devices, and medical devices improve the differences in magnetic core characteristics by creating air gaps of the same size in the magnetic core components of the distributed structure transformer, thereby achieving consistent output voltage of the transformer secondary winding, and / or by connecting capacitors and impedance elements in parallel with the secondary winding. While compensating for the differences in magnetic core characteristics through capacitors, the impedance elements prevent the capacitor from amplifying the uneven voltage of the secondary winding at a specific frequency, thus solving the problem of uneven secondary voltage output corresponding to multiple secondary windings of the transformer. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a high-voltage, high-frequency transformer structure with a concentrated magnetic core in related technologies;

[0019] Figure 2 This is a schematic diagram of the structure of a distributed high-voltage high-frequency transformer in related technologies;

[0020] Figure 3 This is an equivalent circuit diagram of a distributed high-voltage high-frequency transformer in related technologies;

[0021] Figure 4 This is a second-order equivalent circuit diagram of a distributed high-voltage high-frequency transformer in related technologies;

[0022] Figure 5 For the voltage difference transfer function H in related technologiesΔ12_origin (s) amplitude-frequency response curve;

[0023] Figure 6 This is a schematic diagram of a distributed high-voltage high-frequency transformer using parallel capacitors for voltage equalization in one embodiment.

[0024] Figure 7 This is an equivalent circuit diagram of a distributed high-voltage high-frequency transformer using parallel capacitors for voltage equalization in one embodiment.

[0025] Figure 8 This is a second-order equivalent circuit diagram of a distributed high-voltage high-frequency transformer using parallel capacitors for voltage equalization in one embodiment.

[0026] Figure 9 In one embodiment, the voltage difference transfer function H is given when the parallel equalizing capacitors are under heavy load. Δ12_cp (s) amplitude-frequency response curve;

[0027] Figure 10 The voltage difference transfer function H is given by the parallel equalizing capacitors under light load in one embodiment. Δ12_cp (s) amplitude-frequency response curve;

[0028] Figure 11 This is a schematic diagram of a magnetic core assembly with an air gap in one embodiment;

[0029] Figure 12 This is a schematic diagram comparing the magnetization curves of the annular magnetic core before and after the air gap is opened in one embodiment.

[0030] Figure 13 A two-order equivalent circuit diagram of a transformer with an air gap in the core assembly in one embodiment;

[0031] Figure 14 This is a schematic diagram of the transformer structure when a capacitor is connected in series with a resistor in one embodiment;

[0032] Figure 15 This is an equivalent circuit diagram of the transformer when a capacitor is connected in series with a resistor in one embodiment;

[0033] Figure 16 This is a second-order equivalent circuit diagram of the transformer when a capacitor is connected in series with a resistor in one embodiment;

[0034] Figure 17 In one embodiment, the voltage difference transfer function H Δ12_cp+Rd (s) amplitude frequency response curve Figure 1 ;

[0035] Figure 18 In one embodiment, the voltage difference transfer function H Δ12_cp+Rd (s) amplitude frequency response curve Figure 2 ;

[0036] Figure 19 This is a schematic diagram of the transformer structure when the resistor is connected in parallel with the inductor in one embodiment;

[0037] Figure 20 This is a schematic diagram of the transformer structure when the capacitor is connected in series with the inductor in one embodiment;

[0038] Figure 21 This is a schematic diagram of a transformer with an air gap created in the core assembly in one embodiment;

[0039] Figure 22 This is a schematic diagram of a transformer structure in one embodiment where the core assembly has an air gap and a capacitor is connected in parallel to the secondary winding;

[0040] Figure 23 This is a schematic diagram of a transformer structure in one embodiment, where the core assembly has an air gap and the secondary winding has a capacitor and a resistor connected in parallel.

[0041] Figure 24 This is a structural block diagram of a device in one embodiment. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0043] In related technologies, high-voltage high-frequency transformers mostly have a concentrated magnetic core structure, with both the primary and secondary windings wound on the same magnetic circuit. Figure 1 This is a schematic diagram of a concentrated magnetic core high-voltage high-frequency transformer structure in related technologies, such as... Figure 1 In transformers, the low-voltage winding is wrapped around the magnetic core. Meanwhile, high-voltage high-frequency transformers have a large number of high-voltage side windings to achieve high-voltage output. A large number of high-voltage side windings leads to more severe parasitic capacitance and voltage equalization problems. With prolonged use, the high-voltage side windings may be damaged due to partial discharge. Furthermore, because the magnetic core is at ground potential, the voltage between the primary and secondary windings is high. To achieve insulation between the primary and secondary windings, a large amount of insulating material is needed between the primary and secondary windings, as well as within the secondary winding itself. This severely affects the heat dissipation of the high-voltage side windings, potentially causing overheating and damage under high power conditions.

[0044] Figure 2 This is a schematic diagram of a distributed high-voltage high-frequency transformer structure in related technologies, such as... Figure 2 As shown, the primary winding passes through all the magnetic cores and is connected to the inverter circuit, while the high-voltage side winding (secondary winding) is wound on different magnetic cores. After being filtered by the rectifier circuit, it is connected in series to obtain a high-voltage DC output. Figure 2The transformer has 2N secondary windings, where N is a positive integer. In this distributed high-voltage transformer structure, the turns ratio of each high-voltage winding relative to the primary winding can be significantly reduced, greatly alleviating or even eliminating parasitic capacitance and partial discharge problems in the high-voltage windings. Furthermore, this distributed high-voltage transformer structure significantly improves transformer heat dissipation, insulation, and electric field gradient issues. However, because the magnetic cores surrounding each secondary winding may differ by up to 30% in permeability and equivalent cross-sectional area of ​​the magnetic circuit, this will lead to differences in the secondary voltages of each high-voltage winding. Figure 3 It is the equivalent circuit of a distributed high-voltage high-frequency transformer in related technologies, such as Figure 3 In extreme cases, the circuit shown may experience partial breakdown of the winding with excessively high voltage or overvoltage damage to the corresponding rectifier circuit due to excessive voltage difference on the secondary side. Figure 3 In the middle, V in It is the input voltage of the primary winding, V o_n R is the output voltage value corresponding to the Nth secondary winding in the transformer, and R is the equivalent resistance value of the load of the N secondary windings.

[0045] Taking a two-stage distributed high-voltage high-frequency transformer as an example, Figure 4 The second-order equivalent circuit diagram of a distributed high-voltage high-frequency transformer in related technologies is shown below. Figure 4 As shown, V o_1 With V o_2 Voltage difference ΔV between 12 With V in Transfer function H between Δ12_origin (s) is:

[0046]

[0047] Among them, V o_1 R is the secondary voltage value corresponding to the primary winding in a transformer. o_1 L is the equivalent resistance of the circuit load corresponding to the secondary winding in the transformer. m1 It is the equivalent inductance value of the circuit corresponding to a secondary winding in a transformer; V o_2 R is the secondary voltage value corresponding to the other secondary winding in the transformer. o_2 L is the equivalent resistance of the circuit load corresponding to the other secondary winding in the transformer. m2 It is the equivalent inductance value of the circuit corresponding to the other secondary winding in the transformer, and s is the number of turns of the secondary winding.

[0048] With L m1 =1000uH, L m2 =800uH, R under heavy load o_1 =R o_2 =20Ω, R under light load o_1 =R o_2Taking Ω = 500Ω as an example, the voltage difference transfer function H Δ12_origin The amplitude-frequency response curve of (s) is shown in the figure. Figure 5 As shown, where, Figure 5 The horizontal axis represents frequency, and the vertical axis represents voltage difference. From Figure 5 As can be seen, the proportion of voltage difference gradually decreases with increasing frequency. This is because the higher the frequency, the greater the inductive reactance, and the voltage division ratio is mainly determined by the load resistance. On the other hand, in the mid-frequency range, the larger the load resistance, the slower the voltage difference decays. These two points mean that uneven voltage distribution is more likely to occur in the secondary winding under light load or no load, and the degree of uneven voltage distribution is mainly determined by the difference in magnetizing inductance. The greater the difference in magnetic core, the higher the degree of voltage equalization.

[0049] To solve the problem of uneven voltage in the high-voltage winding of a transformer, a voltage-equalizing capacitor C can be connected in parallel to the high-voltage winding. p This is to compensate for the differences in the characteristics of each magnetic core and achieve voltage equalization in the high-voltage side winding. Figure 6 A method using parallel capacitor C is provided p A schematic diagram of a distributed high-voltage high-frequency transformer with voltage equalization. A voltage equalization capacitor C is connected in parallel to the high-voltage side winding. p This can compensate for the differences in characteristics among the various magnetic cores, achieving voltage equalization in the high-voltage side windings. Specifically, Figure 7 To use parallel capacitor C p Equivalent circuit diagram of a distributed high-voltage high-frequency transformer for voltage equalization.

[0050] Taking a two-stage distributed high-voltage high-frequency transformer as an example, Figure 8 To use parallel capacitor C p The second-order equivalent circuit diagram of a distributed high-voltage high-frequency transformer for voltage equalization is shown below. Figure 8 As shown, let R o_1 =R o_2 =R, then V o_1 With V o_2 Voltage difference ΔV between 12 With V in Transfer function H between Δ12_cp (s) is:

[0051]

[0052] With L m1 =1000uH, L m2 =800uH, R under heavy load o_1 =R o_2 =20Ω, R under light load o_1 =R o_2 For example, 500Ω Figure 9 The voltage difference transfer function H is given by the parallel equalizing capacitor Cp under heavy load. Δ12_cp (s) amplitude-frequency response curve; Figure 10 The voltage difference transfer function H is given by the parallel equalizing capacitor Cp under light load. Δ12_cp The amplitude-frequency response curve of (s). Specifically, Figure 9 For heavily loaded transformers, without parallel equalizing capacitor C p and parallel voltage equalizing capacitor C p The amplitude-frequency response curves are shown when the capacitor is 20nF and 200nF, respectively. Figure 10 For a lightly loaded transformer, without parallel equalizing capacitor C p and parallel voltage equalizing capacitor C p The amplitude-frequency response curves are shown for capacitors of 20nF and 200nF, respectively. Figure 9 and Figure 10 It can be seen that the voltage division ratio of a transformer under heavy load is mainly determined by the equivalent load resistance, and the parallel voltage equalization capacitor C p The presence of [something] has virtually no effect on the voltage unevenness; however, when the transformer is lightly loaded, the parallel voltage equalization capacitor C [is involved]. p The presence of this capacitor can significantly reduce the voltage unevenness of the secondary winding at high frequencies, but in some mid-frequency ranges, the parallel capacitor C... p On the contrary, it will amplify the uneven voltage distribution in the secondary winding.

[0053] based on Figure 6 The schematic diagram shows that when the inverter circuit uses pulse frequency modulation, the switching frequency of the input voltage will vary significantly. If the value of the parallel voltage-equalizing capacitor Cp is inappropriate, it may lead to improved voltage equalization of the secondary winding in some frequency bands, while worsening it in others. Therefore, within a certain frequency range, a suitable parallel voltage-equalizing capacitor Cp can indeed improve the voltage equalization of the windings. However, if the value of Cp is inappropriate, it will amplify the voltage imbalance on the high-voltage side winding. Furthermore, the presence of the parallel voltage-equalizing capacitor Cp will increase the reactive circulating current within the power supply, reducing its efficiency. On the other hand, a large parasitic parallel capacitance will affect the operating state of the front-end inverter circuit, limiting the increase in the inverter circuit's switching frequency.

[0054] In view of the above problems, in one embodiment of this application, the transformer includes: a primary winding; a plurality of magnetic core assemblies, the primary winding passing through the plurality of magnetic core assemblies; and a plurality of secondary windings, the secondary windings being wound on each magnetic core assembly respectively.

[0055] The magnetic core assembly is used to concentrate and guide the magnetic field in the transformer. The magnetic core assembly can be made of materials such as silicon steel, iron oxide, and alloys. The magnetic core assembly can be closed or have an air gap. The primary winding is also called the primary winding, and the secondary winding is also called the secondary winding. The primary and secondary windings are part of the transformer's circuitry and are made of wires with relatively high conductivity. Further explanation of the primary and secondary windings follows:

[0056] The primary winding is used to receive the input electrical signal. When alternating current passes through the primary winding, it generates an alternating magnetic field in the core assembly, thereby transferring electrical energy to the secondary winding. The primary winding is a coil made of wire: it can be a single-turn coil or a multi-turn coil wound together; furthermore, the primary winding can be wound around one or more magnetic cores to change the magnetic field distribution of the alternating magnetic field.

[0057] The secondary winding is used to output electrical signals to the load. When an alternating magnetic field is generated in the core assembly, the secondary winding generates an electromotive force, which in turn generates an electric potential, providing electrical energy to the external load. The secondary winding is also a type of coil made of wire: there is a one-to-one correspondence between the core assembly and the secondary winding, with each secondary winding wound around its corresponding core assembly; the winding direction and number of turns of each secondary winding can be the same or different, and are not limited here.

[0058] To address the issue of uneven voltage distribution in the secondary winding of a transformer, the transformer also includes capacitors and impedance elements. The capacitors and impedance elements are connected in series, and the series-connected capacitors and impedance elements are connected to the two ends of the corresponding secondary winding.

[0059] The impedance elements include resistors, inductors, capacitors, and combinations thereof. Specifically, each secondary winding is connected to both ends with a capacitor and an impedance element connected in series. By connecting the impedance element with a capacitor in series, the secondary voltage of the secondary winding can be redistributed based on impedance, thereby reducing the problem of uneven voltage in the secondary winding caused by differences in the characteristics of the magnetic core components.

[0060] Alternatively, to address the issue of uneven voltage distribution in the secondary winding of a transformer, each core assembly may have an air gap of the same size.

[0061] Figure 11 A schematic diagram of a magnetic core assembly with an air gap is provided. It is understood that the cross-section of the magnetic core assembly can also be other shapes besides toroidal, such as rectangular or rectangular cross-sections. Figure 12 This diagram illustrates the comparison of magnetization curves of the toroidal core before and after the air gap is created. The horizontal axis represents magnetization intensity, and the vertical axis represents magnetic flux density. Figure 12 As shown, the permeability difference between the curves of "#1 core" and "#2 core" is large when there is no air gap; the permeability difference between the curves of "#1 core" and "#2 core" is small after an air gap is added. Specifically, the effect of the air gap on the core characteristics is as follows:

[0062] Assume the cross-sectional area of ​​the magnetic core is A e The equivalent length of the magnetic circuit is l c The air gap length is δ, and the relative permeability of the "#1 core" is μ. r1 The relative permeability of the "#2 core" is μr2 For high permeability magnetic cores, μ r1 and μ r2 Both are much greater than 1, and the air gap permeability is μ0. Therefore, the equivalent permeability μ of "#1 core" and "#2 core" after adding the air gap is... e1 and μ e2 They are respectively:

[0063]

[0064] According to the above two equations, the equivalent permeability of the magnetic core after adding an air gap is mainly determined by the air gap itself. Therefore, as long as the air gap length δ of each magnetic core is the same, the influence of the difference in relative permeability of the magnetic cores can be eliminated, ensuring that the excitation inductance of each magnetic core is the same. For ease of understanding, Figure 13 A two-order equivalent circuit diagram of a transformer with an air gap in its core assembly is provided, such as... Figure 13 As shown, V o 1 and V o The voltage difference ΔV between 2 12 With V in Transfer function H between Δ12_gap (s) is:

[0065]

[0066] As can be seen from the above formula, it can be further determined that by adding an air gap of the same size to the magnetic core assembly, the excitation inductance can be made consistent and the uneven voltage of the secondary winding can be eliminated.

[0067] Therefore, by opening air gaps of the same size in each magnetic core, the permeability of the magnetic core assembly can be changed, making the equivalent permeability of each magnetic core consistent, thereby compensating for the differences in the characteristics of each magnetic core, and the excitation inductance also becomes consistent, thus ensuring the voltage equalization of the secondary winding.

[0068] Alternatively, to address the uneven voltage distribution in the secondary windings of a transformer, the transformer may also include capacitors and impedance elements. These capacitors and impedance elements are connected in series, and the series-connected capacitors and impedance elements are connected to the two ends of the corresponding secondary windings. Simultaneously, each core assembly has an air gap of the same size. By connecting a voltage-equalizing capacitor Cp in parallel with the secondary windings, the differences in the characteristics of each core are compensated. The impedance elements connected in series with the capacitors prevent the uneven voltage distribution in the secondary windings from worsening due to improper capacitor values. Furthermore, by creating air gaps in the core assemblies, the permeability of the core assemblies is altered, further compensating for the differences in core characteristics, thereby resolving the uneven voltage distribution across multiple secondary windings of the transformer.

[0069] In this embodiment, based on a distributed transformer, a parallel capacitor is used in the secondary winding to compensate for the differences in characteristics of each magnetic core. This achieves voltage equalization of the high-voltage winding while a damping resistor is connected in series with the capacitor to avoid amplifying the voltage imbalance of the high-voltage winding due to improper capacitor value. And / or, an air gap is opened on each distributed magnetic core. The presence of the air gap improves the difference in magnetic reluctance of each magnetic circuit, thereby compensating for the differences in characteristics of each magnetic core and achieving voltage equalization of multiple secondary windings.

[0070] In one embodiment, the transformer includes multiple rectifier circuits, each connected to a secondary winding. These rectifier circuits convert alternating current (AC) input to the secondary windings into direct current (DC), thereby providing power to the load connected to the transformer. Existing rectifier circuits can be used for rectification, and the results of such rectification are not limited herein.

[0071] In one embodiment, the parameters of the impedance element are determined based on at least one of the following parameters: the frequency of the AC voltage input to the primary winding, the load range of the transformer, the characteristic differences between the core assemblies, and the preset losses of the transformer.

[0072] At the frequency of the AC voltage input to the primary winding, the greater the difference in characteristics between the core components, the larger the parameter values ​​can be selected for the impedance elements. For example, resistors with larger resistance values ​​and inductors with larger inductance values ​​can be selected. Conversely, at the frequency of the AC voltage input to the primary winding, the smaller the difference in characteristics between the core components, the smaller the parameter values ​​can be selected for the impedance elements. For example, resistors with smaller resistance values ​​and inductors with smaller inductance values ​​can be selected.

[0073] When the load range of a transformer is small, the voltage unevenness caused by the characteristic differences between the magnetic core components is more severe, and the impedance element can be selected with a larger parameter value accordingly. When the load range of a transformer is large, the voltage unevenness caused by the characteristic differences between the magnetic core components is relatively minor, and the impedance element can be selected with a smaller parameter value accordingly.

[0074] Differences in characteristics between magnetic core assemblies include, but are not limited to, differences in permeability and cross-sectional area. The greater the difference between core assemblies, the more severe the resulting voltage imbalance, and the larger the parameter values ​​can be selected for the impedance components; conversely, the smaller the difference between core assemblies, the less severe the voltage imbalance, and the smaller the parameter values ​​can be selected for the impedance components.

[0075] The smaller the parameter value of the impedance element in the selected area, the smaller the preset loss of the transformer; the larger the parameter value of the selected impedance element, the greater the preset loss of the transformer.

[0076] In this embodiment, the parameters of the impedance element are determined based on at least one of the following parameters: the frequency of the AC voltage input to the primary winding, the load range of the transformer, the characteristics of the magnetic core assembly, and the preset loss of the transformer. This can specifically ensure voltage equalization of multiple secondary windings and reduce transformer losses.

[0077] Furthermore, when using a capacitor in series with a resistor to achieve voltage equalization, the capacitance value is also determined based on the following parameters: the frequency of the AC voltage input to the primary winding, the load range of the transformer, the characteristic differences between the magnetic core components, and the transformer's preset losses. Specifically, when the AC voltage input to the primary winding is generated by the inverter circuit, the frequency of the AC voltage input to the primary winding is the frequency range of the switching elements in the inverter circuit.

[0078] In one embodiment, the impedance element includes a resistor. Specifically, a capacitor and a resistor are connected in series, and the series-connected capacitor and resistor are connected to both ends of the corresponding secondary winding, so that each secondary winding is connected to both ends of the series-connected capacitor and resistor. The capacitor can be connected in series with a single resistor, or it can be connected in series with a component consisting of multiple resistors.

[0079] Optionally, the transformer includes multiple rectifier circuits, each connected to a secondary winding. When the damping resistor Rd is selected, and the secondary winding, the series-connected resistor and capacitor, and the rectifier circuits are connected in parallel, Figure 14 A schematic diagram of a transformer structure with a capacitor connected in series with a resistor is provided, such as... Figure 14 As shown, the transformer includes N layers of secondary windings, each layer including two secondary windings and a corresponding magnetic core assembly. Figure 15 This is the equivalent circuit diagram of a transformer with a capacitor connected in series with a resistor. For ease of understanding, a two-stage distributed high-voltage high-frequency transformer is used as an example. Figure 16 The second-order equivalent circuit diagram for a transformer capacitor connected in series with a resistor is shown below. Figure 16 As shown, let R o_1 =R o_2 =R,V o_1 With V o_2 Voltage difference ΔV between 12 With V in Transfer function H between Δ12_cp+Rd (s) is:

[0080]

[0081] With L m1 =1000uH, L m2 =800uH, R o_1 =R o_2 For example, 500Ω Figure 17 For the voltage difference transfer function H Δ12_cp+Rd (s) amplitude frequency response curve Figure 1 The corresponding parallel voltage-equalizing capacitor Cp is 20nF, and the series resistor R... d The amplitude-frequency response curves for 2Ω and 10Ω are taken respectively. Figure 18 For the voltage difference transfer function H Δ12_cp+Rd (s) amplitude frequency response curve Figure 2 The corresponding parallel voltage equalizing capacitor Cp is 200nF, and the series resistor R... d The amplitude-frequency response curves for 2Ω and 10Ω are taken respectively.

[0082] Will Figure 17 and Figure 18 and Figure 10 In comparison, it is clear that connecting a suitable damping resistor Rd in series with the equalizing capacitor Cp can not only significantly reduce the voltage unevenness in the high-frequency range, but also avoid the problem of amplifying the voltage unevenness of the secondary winding in some mid-frequency ranges when only the equalizing capacitor Cp is connected in parallel under light load conditions. This is suitable for frequency conversion modulation applications.

[0083] In this embodiment, the parallel capacitor connected to the secondary winding can compensate for the differences in the characteristics of each magnetic core; by connecting a resistor in series with the capacitor, the problem of amplifying the uneven voltage in the secondary winding due to improper capacitor value can be avoided.

[0084] Furthermore, in one embodiment, the impedance element includes a resistor and an inductor connected in parallel. The parallel resistor and inductor together determine the impedance in the circuit, thereby reducing the resistance value required to solve the voltage imbalance problem. Since a lower resistance value results in lower resistance loss, the transformer efficiency can be improved. Optionally, the transformer includes multiple rectifier circuits, each connected to a secondary winding. The impedance element is selected as a damping resistor R. d Inductor L p . Figure 19 A schematic diagram of a transformer with a resistor and inductor connected in parallel is provided, such as... Figure 19 As shown, the damping resistor R d and inductor L p Parallel connection, the resistance R after parallel connection d and inductor L p It is connected in parallel with the secondary winding.

[0085] In one embodiment, the impedance element includes an inductor. Using an inductor instead of a resistor avoids uneven voltage distribution in the secondary winding caused by improper capacitor selection, while also avoiding increased losses due to resistance. Optionally, the transformer includes multiple rectifier circuits, each connected to a separate secondary winding. Figure 20 A schematic diagram of a transformer with a capacitor connected in series with an inductor is provided, as follows: Figure 20 As shown, the impedance element is selected as inductor L. pCapacitor C p and inductor L p Series connection, the capacitor C after series connection p and inductor L p The two ends are connected to the two ends of the secondary winding and the two ends of the rectifier circuit.

[0086] In one embodiment, Figure 21 A schematic diagram of the transformer with an air gap in the core assembly is provided, such as... Figure 21 As shown, each magnetic core assembly has an air gap of the same size; and the transformer includes multiple rectifier circuits, which are connected to each secondary winding respectively.

[0087] Furthermore, in one embodiment, each magnetic core assembly has an air gap of the same size; the transformer includes a capacitor, the two ends of which are connected to the two ends of the secondary winding. Optionally, the transformer includes multiple rectifier circuits. Figure 22 A schematic diagram of a transformer is provided when air gaps are opened in the core assembly and a capacitor is connected in parallel to the secondary winding. By opening air gaps of the same size in each core, the equivalent permeability of each core becomes consistent, and thus the magnetizing inductance also becomes consistent, thereby ensuring voltage equalization in the secondary winding; at the same time, the capacitor can further compensate for the differences in characteristics of each core.

[0088] Furthermore, in one embodiment, each magnetic core assembly has an air gap of the same size; the transformer includes a capacitor and an impedance element, the impedance element being a resistor. Optionally, the transformer also includes a rectifier circuit connected to a plurality of secondary windings respectively. Figure 23 A schematic diagram of a transformer is provided when the magnetic core assembly has an air gap and a capacitor and a resistor are connected in parallel to the secondary winding. The capacitor and resistor are connected in series, and the series-connected capacitor and resistor are connected to both ends of the secondary winding.

[0089] Optionally, each magnetic core assembly has an air gap of the same size; when the transformer includes capacitors and impedance elements, the impedance elements can also be resistors and inductors connected in series, or the impedance elements can also be inductors.

[0090] Based on the same inventive concept, this application also provides a power conversion device for implementing the transformer involved above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more power conversion device embodiments provided below can be found in the limitations of the power conversion method above, and will not be repeated here.

[0091] In one embodiment, such as Figure 24 As shown, a power conversion device is provided, which includes an inverter circuit and a transformer; wherein the inverter circuit is connected to the primary winding of the transformer.

[0092] The transformer includes: a primary winding; multiple core assemblies through which the primary winding passes; multiple secondary windings wound on each core assembly; each core assembly having an air gap of the same size; and / or, the transformer includes a capacitor and an impedance element connected in series, the series-connected capacitor and impedance element being connected to the two ends of the corresponding secondary winding. Optionally, the transformer further includes multiple rectifier circuits connected to each secondary winding.

[0093] In one embodiment, the inverter circuit includes a switching element; wherein the switching element adjusts the current direction in the inverter circuit by changing its on / off state. When each core assembly has an air gap of the same size, although the presence of the air gap will lead to a decrease in the magnetizing inductance and an increase in the magnetizing current, thereby increasing the conduction losses of the switching transistors in the inverter circuit, the magnetizing current can assist the switching transistors in achieving ZVS (Zero Voltage Switching) turn-on, thereby reducing the turn-on losses of the switching transistors. Therefore, from the perspective of total losses, the increase is not significant.

[0094] In one embodiment, the impedance element includes a resistor; or, the impedance element includes a resistor and an inductor connected in parallel; or, the impedance element includes an inductor. The parameters of the impedance element are determined based on at least one of the following parameters: the frequency of the AC voltage input to the primary winding, the load range of the transformer, the characteristics of the core assembly, and the preset losses of the transformer.

[0095] In one embodiment, each magnetic core assembly has an air gap of the same size; the transformer includes a capacitor, the two ends of which are connected to the two ends of the secondary winding.

[0096] Based on the same inventive concept, this application also provides a medical device for implementing the transformer described above. In one embodiment, a medical device is provided that includes the transformer described in the above embodiment. Optionally, by providing a transformer, the electrical signals input to the medical device are transformed and regulated. The medical device may be a CT scanner, X-ray machine, radiotherapy machine, or other equipment that requires a stable and safe power supply environment.

[0097] The transformer includes: a primary winding; multiple core assemblies through which the primary winding passes; multiple secondary windings wound on each core assembly; each core assembly having an air gap of the same size; and / or, the transformer includes a capacitor and an impedance element connected in series, the series-connected capacitor and impedance element being connected to the two ends of the corresponding secondary winding. Optionally, the transformer further includes multiple rectifier circuits connected to each secondary winding.

[0098] In one embodiment, the impedance element includes a resistor; or, the impedance element includes a resistor and an inductor connected in parallel; or, the impedance element includes an inductor. The parameters of the impedance element are determined based on at least one of the following parameters: the frequency of the AC voltage input to the primary winding, the load range of the transformer, the characteristics of the core assembly, and the preset losses of the transformer.

[0099] In one embodiment, each magnetic core assembly has an air gap of the same size; the transformer includes a capacitor, the two ends of which are connected to the two ends of the secondary winding.

[0100] In one embodiment, the inverter circuit includes a switching element; wherein the switching element adjusts the direction of current in the inverter circuit by changing its on / off state.

[0101] The solution provided by this medical device is similar to the solution described in the above method. Therefore, the specific limitations of one or more medical device embodiments provided below can be found in the limitations of the power conversion method above, and will not be repeated here.

[0102] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A transformer, characterized in that, The transformer includes: a primary winding; multiple magnetic core assemblies, the primary winding passing through the multiple magnetic core assemblies; and multiple secondary windings, each secondary winding wound on one of the magnetic core assemblies; wherein... Each of the magnetic core assemblies has an air gap of the same size; and / or, The transformer includes a capacitor and an impedance element, the capacitor being connected in series with the impedance element, and the series-connected capacitor and impedance element being connected to the two ends of the corresponding secondary winding.

2. The transformer according to claim 1, characterized in that, The impedance element includes a resistor.

3. The transformer according to claim 1, characterized in that, The impedance element includes a resistor and an inductor, which are connected in parallel.

4. The transformer according to claim 1, characterized in that, The impedance element includes an inductor.

5. The transformer according to claim 1, characterized in that, Each of the magnetic core assemblies has an air gap of the same size; the transformer includes a capacitor, and the two ends of the capacitor are connected to the two ends of the secondary winding respectively.

6. The transformer according to any one of claims 1 to 5, characterized in that, The transformer includes multiple rectifier circuits, each of which is connected to one of the secondary windings.

7. The transformer according to claim 1, characterized in that, The parameters of the impedance element are determined based on at least one of the following parameters: the frequency of the AC voltage input to the primary winding, the load range of the transformer, the characteristic differences between the core assemblies, and the preset loss of the transformer.

8. A power conversion device, characterized in that, The power conversion device includes: an inverter circuit and a transformer according to any one of claims 1 to 7; wherein the inverter circuit is connected to the primary winding of the transformer.

9. The power conversion device according to claim 8, characterized in that, The inverter circuit includes a switching element; wherein the switching element adjusts the current direction in the inverter circuit by changing its on / off state.

10. A medical device, characterized in that, The transformer includes any one of claims 1 to 7.

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