Linear power supply and electronic equipment
By introducing suppression windings and capacitor modules into the transformer of the linear power supply, the potential of the secondary rectifier circuit is adjusted, and the power frequency interference problem caused by parasitic capacitors of the transformer is solved, thereby achieving lower noise power supply.
Patent Information
- Application Number
- CN202420542791.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-20
- Publication Date
- 2025-02-07
- Estimated Expiration
- 2034-03-20
AI Technical Summary
The parasitic capacitance of the transformer causes the same frequency and phase operation frequency of floating ground to the ground, affecting the normal operation of the circuit.
A linear power supply is designed, including a transformer having a primary winding, a suppression winding and a secondary winding, as well as at least one secondary rectifier circuit and at least one capacitor module. The winding is suppressed to be coupled to the primary winding, and the electric potential of the secondary rectification circuit is adjusted through a capacitance module connected to the ground and secondary rectification circuits to offset the power frequency interference.
It effectively suppresses the power frequency interference caused by parasitic capacitors, improves the noise suppression ability of linear power supply, and ensures the normal operation of the circuit.
Smart Images
Figure CN222441570U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of linear power supplies, and in particular to a linear power supply and an electronic device. Background Art
[0002] Some floating ground circuits require low power supply noise, so they abandon switching power supplies and choose linear power supplies with single-phase power frequency transformers. Because there is parasitic capacitance between the primary winding and the secondary winding of the transformer, the AC high voltage signal of the primary winding is coupled to the secondary winding to generate common-mode voltage interference, which is specifically manifested as the floating reference ground having the same frequency and phase power frequency interference to the earth, thus affecting the normal operation of the circuit.
[0003] In the current technical solution, the parasitic capacitance is reduced by adding a shielding layer grounding between the primary winding and the secondary winding of the transformer. However, the shielding layer needs to ensure the shielding effect, and it often takes up a large all-round space during the winding process, which makes it difficult to implement and affects the normal magnetic field coupling of the transformer. Therefore, a new technical solution is needed. Utility Model Content
[0004] The main technical problem solved by the present application is the interference of the parasitic capacitance of the transformer.
[0005] According to a first aspect, an embodiment provides a linear power supply, comprising:
[0006] A transformer, comprising a primary winding, a suppression winding and at least one secondary winding, wherein the primary winding has an AC positive terminal and an AC negative terminal for inputting an AC signal, and the suppression winding and at least one secondary winding are respectively coupled to the primary winding; wherein the AC positive terminal of the primary winding and the first terminal of the suppression winding are terminals of the same name, and the AC negative terminal of the primary winding and the second terminal of the suppression winding are terminals of the same name;
[0007] At least one secondary rectifier circuit, the input end of each secondary rectifier circuit is connected to the output end of a corresponding secondary winding, each secondary rectifier circuit rectifies the input AC signal and outputs a DC signal, and the at least one secondary rectifier circuit has a floating ground;
[0008] at least one capacitor module;
[0009] The first end of the suppression winding is used to be connected to the ground, and the second end of the suppression winding is respectively connected to each of the secondary rectifier circuits; wherein, the first end of the suppression winding is used to be connected to the ground after being connected in series with the capacitor module, and / or the second end of the suppression winding is respectively connected in series with the capacitor module and then connected to each of the secondary rectifier circuits.
[0010] In some embodiments, each of the floating grounds is connected to the ground via a capacitor.
[0011] In some embodiments, the second end of the suppression winding is respectively connected to the floating ground of each of the secondary rectifier circuits; or, the second end of the suppression winding is respectively connected in series with the capacitor module and then connected to the floating ground of each of the secondary rectifier circuits.
[0012] In some embodiments, the AC signal is AC mains, the transformer is an industrial frequency transformer, the AC positive end of the primary winding is used to connect to the live wire of the AC mains, and the AC positive end is used to connect to the neutral wire of the AC mains.
[0013] In some embodiments, the capacitor module includes at least one capacitor, and the at least one capacitor is connected in series and / or in parallel to meet a preset capacitance value and a preset withstand voltage value.
[0014] In some embodiments, the at least one capacitor is a high-voltage capacitor.
[0015] In some embodiments, the secondary rectifier circuit includes a rectifier bridge, a first end and a second end of the rectifier bridge are respectively connected to two ends of the secondary winding, and a third end and a fourth end of the rectifier bridge are used to output a DC signal.
[0016] In some embodiments, the secondary rectifier circuit further includes a filter capacitor, and the filter capacitor is connected in parallel between the third terminal and the fourth terminal of the rectifier bridge.
[0017] According to a second aspect, an embodiment provides an electronic device, including a load, and the electronic device further includes the linear power supply as described in the first aspect, wherein the linear power supply is used to power the load.
[0018] According to the linear power supply of the above embodiment, since the AC positive end of the primary winding and the first end of the suppression winding are the same-named ends, and the first end of the suppression winding is used to connect to the ground, when the voltage input to the AC positive end of the primary winding is positive and the potential of the entire secondary rectifier circuit and its floating ground is raised, the voltage of the first end of the suppression winding is higher than the voltage of its second end, so that the current on the secondary rectifier circuit flows to the ground, thereby lowering the potential of the entire secondary rectifier circuit and its floating ground. Conversely, when the voltage input to the AC positive end of the primary winding is negative and the potential of the entire secondary rectifier circuit and its floating ground is lowered, the voltage of the first end of the suppression winding is lower than the voltage of its second end, so that the current of the suppression winding flows to the secondary rectifier circuit, thereby raising the potential of the entire secondary rectifier circuit and its floating ground, thereby suppressing the interference generated by the parasitic capacitance of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a structural schematic diagram of a linear power supply in the prior art;
[0020] Figure 2 A schematic diagram of the structure of a linear power supply according to an embodiment;
[0021] Figure 3 FIG. 4 is a schematic diagram of the structure of a linear power supply according to another embodiment. DETAILED DESCRIPTION
[0022] The present application is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments use associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present application to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, and methods. In some cases, some operations related to the present application are not shown or described in the specification, in order to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and the related operations can be fully understood according to the description in the specification and the general technical knowledge in the art.
[0023] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).
[0024] In the current solution, the structure of the linear power supply is as follows Figure 1 As shown, GND_EARTH is the earth, T1 is a single-phase power frequency transformer, capacitor C1 is the parasitic coupling capacitor between the primary winding N1 and the secondary winding N2 of transformer T1, and the connection is represented by a dotted line. The floating ground is GND1. In order to ensure that the voltage difference between the floating ground and the earth is relatively stable and not affected by noise, a certain capacitance is required, and C3 is the capacitance from the secondary rectifier circuit to the earth, which includes real capacitance and parasitic capacitance, and the connection is represented by a dotted line.
[0025] When the voltage of the live wire L is positive, due to the coupling effect of the parasitic capacitor C1, the secondary winding N2 and the secondary floating secondary rectifier circuit have an electric potential increase; when the voltage of the live wire L is negative, due to the coupling effect of the parasitic capacitor C1, the secondary winding N2 and the secondary floating secondary rectifier circuit have an electric potential decrease. The above-mentioned potential increase and decrease can all be summarized as the positive and negative pressure of the floating ground GND1 to the earth GND_EARTH. The frequency is the industrial frequency of the AC mains, and the phase of its waveform is the same as the phase of the live wire L, and this is the industrial frequency interference introduced by the linear power supply.
[0026] In some embodiments of the present application, a suppression winding is additionally added, and the suppression winding is also coupled to the primary winding. When the potential of the secondary rectifier circuit is raised, the potential of the secondary rectifier circuit is lowered through the suppression winding. Conversely, when the potential of the secondary rectifier circuit is lowered, the potential of the secondary rectifier circuit is raised through the suppression winding, thereby offsetting most of the power frequency interference, so as to effectively suppress the power frequency interference introduced by the linear power supply.
[0027] Some embodiments provide a linear power supply for converting an AC signal into a DC signal and eliminating interference caused by the frequency of the AC signal. Figure 2 The linear power supply includes a transformer, at least one secondary rectifier circuit and at least one capacitor module, which are described in detail below.
[0028] The transformer has a primary winding, a suppression winding and at least one secondary winding. In some embodiments, the primary winding has an AC positive terminal and an AC negative terminal for inputting an AC signal, for example, it can be an input AC mains, wherein the AC positive terminal of the primary winding is used to connect the live wire L, and the AC negative terminal of the primary winding is used to connect the neutral wire N, and the far end of the neutral wire is connected to the earth, and its potential is approximately equal to the earth, and the live wire L is an AC voltage with the neutral wire N as a reference, wherein the extension and connection are represented by a dotted line. At this time, the transformer can be an industrial frequency transformer, and the interference introduced by the AC mains is industrial frequency interference. The suppression winding and at least one secondary winding are respectively coupled to the primary winding, and respectively obtain the energy transmitted by the primary winding based on electromagnetic induction.
[0029] The secondary rectifier circuit is used to convert an AC signal into a DC signal, and the secondary rectifier circuit has a floating ground, which is connected to the ground through a capacitor. In some embodiments, the secondary rectifier circuit includes a rectifier bridge D41, which is composed of four diodes, wherein the first end and the second end of the rectifier bridge D41 are respectively connected to the two ends of the secondary winding, so as to input an AC signal, and the rectifier bridge D41 converts the AC signal into a DC signal, and outputs the DC signal from its third end and fourth end. In some embodiments, the secondary rectifier circuit also includes a filter capacitor C42, which is connected in parallel between the third end and the fourth end of the rectifier bridge D41, and is used to filter out interference in the DC signal, so that the DC signal becomes smooth. In some embodiments, the number of secondary rectifier circuits corresponds to the number of secondary windings, that is, one secondary rectifier circuit corresponds to one secondary winding, and is used to convert the AC signal generated by the secondary winding into a DC signal. For example, refer to Figure 2 , the primary coil is N1, the suppression winding is N3, and there is one secondary winding, namely the secondary winding N2, refer to Figure 3, the primary coil is N1, the suppression winding is N4, there are two secondary windings, namely secondary winding N2 and secondary winding N3, the secondary rectifier circuit corresponding to the secondary winding N2 is the first secondary rectifier circuit, and the secondary rectifier circuit corresponding to the secondary winding N3 is the second secondary rectifier circuit.
[0030] In some embodiments, the AC positive end of the primary winding and the first end of the suppression winding are the same-named ends, and the AC negative end of the primary winding and the second end of the suppression winding are the same-named ends. The first end of the suppression winding is used to be connected to the ground, and the second end of the suppression winding is respectively connected to each secondary rectifier circuit. Among them, the first end of the suppression winding is used to be connected to the ground after being connected in series with a capacitor module, and / or the second end of the suppression winding is respectively connected in series with a capacitor module and then connected to each secondary rectifier circuit, that is, the suppression winding needs to be connected in series with a capacitor module before being used to connect the ground and the secondary rectifier circuit. In some embodiments, the second end of the suppression winding is respectively connected to the floating ground of each secondary rectifier circuit, or the second end of the suppression winding is respectively connected in series with a capacitor module and then connected to the floating ground of each secondary rectifier circuit.
[0031] In some embodiments, each capacitor module includes at least one capacitor, and the at least one capacitor is connected in series and / or in parallel to meet a preset capacitance value and a preset withstand voltage value. In some embodiments, the at least one capacitor is a high-voltage capacitor to meet the floating isolation requirement of the secondary rectifier circuit.
[0032] The above are some explanations of linear power supplies. The following is a specific explanation of the principle of interference suppression of linear power supplies.
[0033] Please refer to Figure 2 , when the voltage of the live wire L is positive, it can be seen from the above that the parasitic capacitor C41 of the transformer T41 will raise the potential of the entire secondary rectifier circuit and its floating ground GND1. At the same time, since the first end of the suppression winding N3 and the end of the primary winding N1 connected to the live wire are the same end, the voltage of the first end of the suppression winding N3 is higher than the voltage of its second end. At this time, the current direction on the suppression winding is GND1, capacitor C45, suppression winding N3, capacitor C46 and earth GND_EARTH, thereby lowering the potential of the entire secondary rectifier circuit and its floating ground GND1. Similarly, when the voltage of the live wire L is negative, the parasitic capacitor C41 lowers the potential of the entire secondary rectifier circuit and its floating ground GND1. At this time, the voltage of the first end of the suppression winding N3 is lower than the voltage of its second end, thereby raising the potential of the entire secondary rectifier circuit and its floating ground GND1. Therefore, the power frequency interference can be offset and suppressed by suppressing the winding N3.
[0034] Please refer to Figure 2, and from the perspective of the common-mode current forming the common-mode voltage, when the common-mode current is input into the primary winding N1 of the transformer T41, it passes through the parasitic capacitor C41, the secondary winding N2, the floating ground GND1 and the capacitor C43, thus forming a loop with the ground GND_EARTH. After adding the suppression winding N3 and the capacitors C45 and C46, the common-mode current that originally flows through the capacitor C43 is absorbed, so that the capacitor C43 has no current and no charge or discharge, but the voltage is stable, that is, the secondary rectifier circuit with the floating ground GND1 as the reference stabilizes the voltage of the ground GND_EARTH, so that the power frequency interference is suppressed.
[0035] In the above embodiment, the suppression winding N3 and the capacitor module are introduced, and by adjusting the equivalent capacitance and withstand voltage of the capacitor module to adapt it to the system, most of the power frequency interference can be offset to achieve the suppression effect. Among them, if the capacitance is too small, the degree of offset will be insufficient, and if the capacitance is too large, it will be overcorrected. Therefore, a suitable equivalent capacitance can achieve a better power frequency interference suppression effect.
[0036] In the above embodiment, the suppression winding can be connected to any position of the secondary rectifier circuit to raise or lower the potential of the secondary rectifier circuit. However, when the suppression winding is connected to the secondary rectifier circuit in a floating manner, the power frequency interference suppression effect is better.
[0037] In the above embodiment, the suppression winding can be used to suppress power frequency interference of a secondary rectifier circuit of a single secondary winding, and can also be used to suppress power frequency interference of a secondary rectifier circuit of multiple secondary windings.
[0038] Some embodiments provide an electronic device, which includes a load and a linear power supply. The linear power supply is the linear power supply in the above embodiment, and the linear power supply is used to power the load.
[0039] The above specific examples are used to illustrate the present application, which is only used to help understand the present application and is not intended to limit the present application. For technicians in the technical field to which the present application belongs, they can also make some simple deductions, deformations or substitutions based on the ideas of the present application.
Claims
1. A linear power supply, characterized in that: include: A transformer, comprising a primary winding, a suppression winding and at least one secondary winding, wherein the primary winding has an AC positive terminal and an AC negative terminal for inputting an AC signal, and the suppression winding and at least one secondary winding are respectively coupled to the primary winding; wherein the AC positive terminal of the primary winding and the first terminal of the suppression winding are terminals of the same name, and the AC negative terminal of the primary winding and the second terminal of the suppression winding are terminals of the same name; At least one secondary rectifier circuit, the input end of each secondary rectifier circuit is connected to the output end of a corresponding secondary winding, each secondary rectifier circuit rectifies the input AC signal and outputs a DC signal, and the at least one secondary rectifier circuit has a floating ground; at least one capacitor module; The first end of the suppression winding is used to be connected to the ground, and the second end of the suppression winding is respectively connected to each of the secondary rectifier circuits; wherein, the first end of the suppression winding is used to be connected to the ground after being connected in series with the capacitor module, and / or the second end of the suppression winding is respectively connected in series with the capacitor module and then connected to each of the secondary rectifier circuits.
2. The linear power supply according to claim 1, characterized in that , each of the floating grounds is connected to the ground through a capacitor.
3. The linear power supply according to claim 1, characterized in that: The second end of the suppression winding is respectively connected to the floating ground of each of the secondary rectifier circuits; or, the second end of the suppression winding is respectively connected in series with the capacitor module and then connected to the floating ground of each of the secondary rectifier circuits.
4. The linear power supply according to claim 1, characterized in that: The AC signal is AC mains power, the transformer is an industrial frequency transformer, the AC positive end of the primary winding is used to connect to the live wire of the AC mains power, and the AC negative end is used to connect to the neutral wire of the AC mains power.
5. The linear power supply according to claim 1, characterized in that: The capacitor module includes at least one capacitor, and the at least one capacitor is connected in series and / or in parallel to meet a preset capacitance value and a preset withstand voltage value.
6. The linear power supply according to claim 5, characterized in that: The at least one capacitor is a high-voltage capacitor.
7. The linear power supply according to claim 1, characterized in that: The secondary rectifier circuit comprises a rectifier bridge, a first end and a second end of the rectifier bridge are respectively connected to two ends of the secondary winding, and a third end and a fourth end of the rectifier bridge are used to output a DC signal.
8. The linear power supply according to claim 7, characterized in that: The secondary rectifier circuit further includes a filter capacitor, which is connected in parallel between the third terminal and the fourth terminal of the rectifier bridge.
9. An electronic device, comprising a load, characterized in that: It also includes a linear power supply as claimed in any one of claims 1 to 8, wherein the linear power supply is used to power the load.