Transformer winding current-sharing power supply and electric equipment

Abstract

The invention discloses a transformer winding current-sharing power supply and electric equipment, the transformer winding current-sharing power supply comprises a transformer, the transformer is provided with a primary side winding connected with a primary side circuit, a first secondary side winding connected with a first secondary side circuit, and a second secondary side winding connected with a second secondary side circuit, the first secondary side circuit and the second secondary side circuit are connected to the same load output, the current sharing circuit is connected between the first secondary side circuit and the second secondary side circuit, and the current sharing circuit is used for balancing current on the first secondary side circuit and the second secondary side circuit. Compared with the prior art, the problem of non-uniform current of the transformer winding can be simply and efficiently solved through fewer devices.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply design, and particularly to a power supply and an electrical equipment with uniform current sharing in transformer windings. Background Art

[0002] In power supply products, a transformer is a common and essential component. When the impedances of the windings of a transformer and the circuits where they are located cannot be made consistent, if the two windings of the transformer operate in parallel, there will be a problem of non-uniform current sharing in the output currents of the two windings of the transformer. In such a case, it is possible that one winding of the transformer operates under overload, while the other winding of the transformer operates under light load. Using the transformer windings in this way for a long time will cause the transformer windings to overheat, resulting in a sharp decline in the product life.

[0003] Therefore, how to design a power supply and an electrical equipment with uniform current sharing in transformer windings to avoid the above problem of non-uniform current sharing in transformer windings is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0004] Aiming at the problem of non-uniform current sharing in the windings of a transformer in the prior art, the present invention proposes a power supply and an electrical equipment with uniform current sharing in transformer windings.

[0005] The technical solution of the present invention is to provide a power supply with uniform current sharing in transformer windings, including a transformer, the transformer having a primary winding connected to a primary circuit, a first secondary winding connected to a first secondary circuit, and a second secondary winding connected to a second secondary circuit, the first secondary circuit and the second secondary circuit being connected to the same load output, and further including a current sharing circuit connected between the first secondary circuit and the second secondary circuit, the current sharing circuit being used to balance the currents on the first secondary circuit and the second secondary circuit.

[0006] Further, the current sharing circuit is a common mode inductor composed of a third coil winding provided in the first secondary circuit and a fourth coil winding provided in the second secondary circuit.

[0007] Further, the first secondary circuit includes a winding internal resistance Ro1, a trace resistance Rc1, diodes D1, D2, D3, and D4;

[0008] The diodes D1, D2, D3, and D4 form a full bridge circuit, and the diodes D1 and D3 form a first bridge arm, and the diodes D2 and D4 form a second bridge arm;

[0009] The non - same - name terminals of the first secondary winding are connected to the mid - point of the first bridge arm after being serially connected with the winding internal resistance Ro1, the same - name terminals of the first secondary winding are connected to the mid - point of the second bridge arm, the cathodes of the diode D1 and the diode D2 are connected together and then serially connected with the trace resistance Rc1 and connected to one end of the load, and the anodes of the diode D3 and the diode D4 are connected together and then connected to the other end of the load.

[0010] Further, the second secondary circuit includes a winding internal resistance Ro2, a trace resistance Rc2, a diode D5, a diode D6, a diode D7, and a diode D8;

[0011] The diode D5, the diode D6, the diode D7, and the diode D8 form a full - bridge circuit, and the diode D5 and the diode D7 form the third bridge arm, and the diode D6 and the diode D8 form the fourth bridge arm;

[0012] The non - same - name terminals of the second secondary winding are connected to the mid - point of the third bridge arm after being serially connected with the winding internal resistance Ro2, the same - name terminals of the second secondary winding are connected to the mid - point of the fourth bridge arm, the cathodes of the diode D5 and the diode D6 are connected together and then serially connected with the trace resistance Rc2 and connected to one end of the load, and the anodes of the diode D7 and the diode D8 are connected together and then connected to the other end of the load.

[0013] Further, the third coil winding is serially connected between the same - name terminals of the first secondary winding and the mid - point of the second bridge arm, and the same - name terminals of the third coil winding are connected to the same - name terminals of the first secondary winding;

[0014] The fourth coil winding is serially connected between the non - same - name terminals of the second secondary winding and the winding internal resistance Ro2, and the same - name terminals of the fourth coil winding are connected to the non - same - name terminals of the second secondary winding.

[0015] Further, the first secondary circuit includes a winding internal resistance Ro1, a trace resistance Rc1, a diode D1, a diode D2, a diode D3, and a diode D4;

[0016] The diode D1, the diode D2, the diode D3, and the diode D4 form a full - bridge circuit, and the diode D1 and the diode D3 form the first bridge arm, and the diode D2 and the diode D4 form the second bridge arm;

[0017] The same-named ends of the first secondary winding are connected to the midpoint of the first bridge arm after being connected in series with the winding internal resistance Ro1, and the different-named ends of the first secondary winding are connected to the midpoint of the second bridge arm. The cathodes of the diode D1 and the diode D2 are connected together and then connected in series with the trace resistance Rc1 to one end of the load, and the anodes of the diode D3 and the diode D4 are connected together and then connected to the other end of the load.

[0018] Further, the second secondary circuit includes a winding internal resistance Ro2, a trace resistance Rc2, a diode D5, a diode D6, a diode D7, and a diode D8;

[0019] The diode D5, the diode D6, the diode D7, and the diode D8 form a full-bridge circuit, and the diode D5 and the diode D7 form a third bridge arm, and the diode D6 and the diode D8 form a fourth bridge arm;

[0020] The same-named ends of the second secondary winding are connected to the midpoint of the third bridge arm after being connected in series with the winding internal resistance Ro2, and the different-named ends of the second secondary winding are connected to the midpoint of the fourth bridge arm. The cathodes of the diode D5 and the diode D6 are connected together and then connected in series with the trace resistance Rc2 to one end of the load, and the anodes of the diode D7 and the diode D8 are connected together and then connected to the other end of the load.

[0021] Further, the third coil winding is connected in series between the different-named end of the first secondary winding and the midpoint of the second bridge arm, and the different-named end of the third coil winding is connected to the different-named end of the first secondary winding;

[0022] The fourth coil winding is connected in series between the same-named end of the second secondary winding and the winding internal resistance Ro2, and the different-named end of the fourth coil winding is connected to the same-named end of the second secondary winding.

[0023] The present invention also provides an electrical device, and the electrical device has a power supply with the above-mentioned current sharing of the transformer windings.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] In the present invention, by adding a common-mode inductor between the first secondary circuit and the second secondary circuit of the transformer, and utilizing the characteristics of the common-mode inductor itself, the currents in the first secondary circuit and the second secondary circuit are balanced, thereby avoiding the problem of uneven current sharing in the transformer windings. Compared with the traditional design scheme, the present invention uses fewer components and can simply and efficiently solve the problem of uneven current sharing in the transformer windings. Description of the Drawings

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 Schematic diagram of the principle of the power supply for current sharing of transformer windings in the present invention;

[0028] Figure 2 Schematic connection diagram of a two-winding transformer in the prior art during application;

[0029] Figure 3 For Figure 2 Schematic diagram of the voltage and current waveforms in the embodiment;

[0030] Figure 4 Schematic diagram of the specific circuit connection of the power supply for current sharing of transformer windings in the present invention;

[0031] Figure 5 For Figure 4 Schematic diagram of the voltage and current waveforms in the embodiment. Specific embodiments

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clear, the following further details the present invention in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] Therefore, a feature pointed out in this specification will be used to illustrate one feature of one embodiment of the present invention, rather than implying that each embodiment of the present invention must have the described feature. In addition, it should be noted that this specification describes many features. Although some features can be combined to show possible system designs, these features can also be used in other combinations not explicitly described. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0034] The following details the principle and structure of the present invention in conjunction with the drawings and embodiments.

[0035] Please refer to Figure 2, which is a schematic diagram of the connection of a transformer to a power supply circuit in the prior art. The transformer has a primary winding Lp, a first secondary winding Ls1, and a second secondary winding Ls2. The circuit connected to the back end of the first secondary winding Ls1 is the first secondary circuit, and a winding internal resistance Ro1 is connected to its opposite ends. The resistance value of the winding internal resistance Ro1 is 0.1 ohm. The circuit connected to the back end of the second secondary winding Ls2 is the second secondary circuit, and a winding internal resistance Ro2 is connected to its opposite ends. The resistance value of the winding internal resistance Ro2 is 10 ohms. The outputs of the first secondary circuit and the second secondary circuit are connected to the same load Load.

[0036] Here, the impedance on the line of the first secondary winding Ls1 is 0.1 ohm, and the impedance on the line of the second secondary winding Ls2 is 10 ohms. The first secondary winding Ls1 and the second secondary winding Ls2 are connected in parallel to the load Load after full-wave rectification. Since the impedance on the line of the first secondary winding Ls1 is quite different from the impedance on the line of the second secondary winding Ls2, please refer to Figure 3 , at this time, the average value of the rectified current I(Rc1) of the first secondary winding Ls1 is about 3A, and the average value of the rectified current I(Rc2) of the second secondary winding Ls2 is about 0A. At this time, the currents on the first secondary winding Ls1 and the second secondary winding Ls1 are seriously uneven, which may cause the windings of the transformer to overheat, thereby shortening its service life.

[0037] Based on the above problems, the design idea of the present invention is to set up a current sharing circuit between the first secondary circuit and the second secondary circuit. The current sharing circuit is composed of a common-mode inductor, and the characteristic of the self-voltage balance of the common-mode inductor is utilized to achieve the effect of current sharing.

[0038] Please refer to Figure 4 , which is the power supply for current sharing of the transformer windings proposed by the present invention. It includes a transformer, which has a primary winding Lp connected to the primary circuit, a first secondary winding Ls1 connected to the first secondary circuit, and a second secondary winding Ls2 connected to the second secondary circuit. Among them, the first secondary circuit and the second secondary circuit are connected to the same load output;

[0039] The above setting further includes a current sharing circuit connected between the first secondary circuit and the second secondary circuit. The current sharing circuit is used to balance the currents on the first secondary circuit and the second secondary circuit.

[0040] The current sharing circuit specifically includes a third coil winding L3 and a fourth coil winding L4. Among them, the third coil winding L3 is arranged in the first secondary circuit, the fourth coil winding L4 is arranged in the second secondary circuit, and the third coil winding L3 and the fourth coil winding L4 form a common-mode inductor.

[0041] In a working circuit, a common-mode inductor generally has only one loop, enabling current to flow through two coil windings simultaneously, forming a mutually canceling magnetic field. Its current is mainly affected by the resistance of the coil itself and the damping of the leakage inductance at a negligible operating frequency. Since the resistances of the third coil winding L3 and the fourth coil winding L4 are basically the same, after setting the above-mentioned common-mode inductor into the first secondary circuit and the second secondary circuit, current sharing of the first secondary winding Ls1 and the second secondary winding Ls2 of the transformer can be achieved.

[0042] Figure 1 This is the schematic diagram of the design of the common-mode inductor of the present invention. For the first secondary winding Ls1, its current flows in from the opposite-named terminal. Therefore, for the third coil winding L3, its current flows in from the same-named terminal and flows out from its opposite-named terminal. Similarly, for the second secondary winding Ls2, its current flows out from the same-named terminal. Therefore, for the fourth coil winding L4, its current flows in from the opposite-named terminal and flows out from its same-named terminal. After the third coil winding L3 and the fourth coil winding L4 form a common-mode inductor, its current can flow in from the same-named terminal of the third coil winding L3 and finally flow out from the same-named terminal of the fourth coil winding L4, thus forming a loop to achieve the above-mentioned current-sharing effect.

[0043] The above Figure 1 This is the connection method under a preferred embodiment of the present invention. In other embodiments of the present invention, the connection methods of the first secondary winding Ls1, the second secondary winding Ls2, the third coil winding L3, and the fourth coil winding L4 can also be adjusted, such that the same-named terminal of the third coil winding L3 is connected to the same-named terminal of the first secondary winding Ls1, and the same-named terminal of the fourth coil winding L4 is connected to the opposite-named terminal of the second secondary winding Ls2. At this time, the current can also flow in from the same-named terminal of the third coil winding L3 and finally flow out from the same-named terminal of the fourth coil winding L4, thus forming a loop to achieve the above-mentioned current-sharing effect.

[0044] Specifically, based on the above idea, please refer to Figure 4 , the first secondary circuit in the present invention can be designed as:

[0045] The first secondary circuit includes a winding internal resistance Ro1, a trace resistance Rc1, diodes D1, D2, D3, and D4;

[0046] Among them, diodes D1, D2, D3, and D4 form a full-bridge circuit, and diodes D1 and D3 form the first bridge arm, while diodes D2 and D4 form the second bridge arm;

[0047] The opposite-name ends of the first secondary winding are connected to the midpoint of the first bridge arm after being serially connected with the winding internal resistance Ro1, and the same-name ends of the first secondary winding are connected to the midpoint of the second bridge arm. The cathodes of diode D1 and diode D2 are connected together and then serially connected with the trace resistance Rc1 and connected to one end of the load. The anodes of diode D3 and diode D4 are connected together and then connected to the other end of the load.

[0048] The second secondary circuit can be designed as:

[0049] The second secondary circuit includes a winding internal resistance Ro2, a trace resistance Rc2, diode D5, diode D6, diode D7, and diode D8;

[0050] Among them, diode D5, diode D6, diode D7, and diode D8 form a full-bridge circuit, and diode D5 and diode D7 form the third bridge arm, and diode D6 and diode D8 form the fourth bridge arm;

[0051] The opposite-name ends of the second secondary winding are connected to the midpoint of the third bridge arm after being serially connected with the winding internal resistance Ro2, and the same-name ends of the second secondary winding are connected to the midpoint of the fourth bridge arm. The cathodes of diode D5 and diode D6 are connected together and then serially connected with the trace resistance Rc2 and connected to one end of the load. The anodes of diode D7 and diode D8 are connected together and then connected to the other end of the load.

[0052] Then, the third coil winding is serially connected between the same-name end of the first secondary winding and the midpoint of the second bridge arm, and the same-name end of the third coil winding is connected to the same-name end of the first secondary winding;

[0053] The fourth coil winding is serially connected between the opposite-name end of the second secondary winding and the winding internal resistance Ro2, and the same-name end of the fourth coil winding is connected to the opposite-name end of the second secondary winding.

[0054] At this time, the same-name end of the third coil winding L3 is connected to the same-name end of the first secondary winding Ls1, and the same-name end of the fourth coil winding L4 is connected to the opposite-name end of the second secondary winding Ls2. The current enters from the same-name end of the third coil winding L3 and finally exits from the same-name end of the fourth coil winding L4, thereby forming a loop to achieve the above-mentioned current sharing effect.

[0055] In another embodiment of the present invention, the first secondary circuit in the present invention can be designed as:

[0056] The first secondary circuit includes a winding internal resistance Ro1, a trace resistance Rc1, diode D1, diode D2, diode D3, and diode D4;

[0057] Among them, diode D1, diode D2, diode D3, and diode D4 form a full-bridge circuit, and diode D1 and diode D3 form the first bridge arm, and diode D2 and diode D4 form the second bridge arm;

[0058] The same - named terminal of the first secondary winding is connected to the mid - point of the first bridge arm after being in series with the internal resistance Ro1 of the winding, and the different - named terminal of the first secondary winding is connected to the mid - point of the second bridge arm. The cathodes of diode D1 and diode D2 are connected together and then connected to one end of the load after being in series with the trace resistance Rc1. The anodes of diode D3 and diode D4 are connected together and then connected to the other end of the load.

[0059] The second secondary circuit can be designed as:

[0060] The second secondary circuit includes the winding internal resistance Ro2, the trace resistance Rc2, diode D5, diode D6, diode D7, and diode D8;

[0061] Among them, diode D5, diode D6, diode D7, and diode D8 form a full - bridge circuit, and diode D5 and diode D7 form the third bridge arm, while diode D6 and diode D8 form the fourth bridge arm;

[0062] The same - named terminal of the second secondary winding is connected to the mid - point of the third bridge arm after being in series with the winding internal resistance Ro2, and the different - named terminal of the second secondary winding is connected to the mid - point of the fourth bridge arm. The cathodes of diode D5 and diode D6 are connected together and then connected to one end of the load after being in series with the trace resistance Rc2. The anodes of diode D7 and diode D8 are connected together and then connected to the other end of the load.

[0063] Then, the third coil winding is connected in series between the different - named terminal of the first secondary winding and the mid - point of the second bridge arm, and the different - named terminal of the third coil winding is connected to the different - named terminal of the first secondary winding;

[0064] The fourth coil winding is connected in series between the same - named terminal of the second secondary winding and the winding internal resistance Ro2, and the different - named terminal of the fourth coil winding is connected to the same - named terminal of the second secondary winding.

[0065] At this time, the different - named terminal of the third coil winding L3 is connected to the different - named terminal of the first secondary winding Ls1, and the different - named terminal of the fourth coil winding L4 is connected to the same - named terminal of the second secondary winding Ls2. The current can enter from the same - named terminal of the third coil winding L3 and finally exit from the same - named terminal of the fourth coil winding L4, thus forming a loop to achieve the above - mentioned current sharing effect.

[0066] Please refer to Figure 5 , after the above - mentioned settings, at this time, the average value I(Rc1) of the rectified current of the first secondary winding Ls1 is about 1.5 A, and the average value I(Rc2) of the rectified current of the second secondary winding Ls2 is about 1.5 A. At this time, the currents on the first secondary winding Ls1 and the second secondary winding Ls1 are very balanced, avoiding the problem of winding life attenuation caused by uneven current in the prior art.

[0067] The present invention also provides an electrical device having a power supply with balanced current in the above-mentioned transformer windings.

[0068] In summary, compared with the prior art, the present invention has at least the following beneficial effects:

[0069] In the present invention, a common-mode inductor is added between the first secondary circuit and the second secondary circuit of the transformer. By utilizing the characteristics of the common-mode inductor itself, the currents in the first secondary circuit and the second secondary circuit are balanced, thereby avoiding the problem of unbalanced current in the transformer windings. Compared with the traditional design scheme, the present invention uses fewer components and can simply and efficiently solve the problem of unbalanced current in the transformer windings.

[0070] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A power supply for current sharing in a transformer winding, comprising a transformer having a primary winding connected to a primary circuit, a first secondary winding connected to a first secondary circuit, and a second secondary winding connected to a second secondary circuit, wherein the first secondary circuit and the second secondary circuit are connected to the same load output, characterized in that, It further includes a current sharing circuit connected between the first secondary circuit and the second secondary circuit, and the current sharing circuit is used to balance the currents on the first secondary circuit and the second secondary circuit.

2. The power supply for equalizing current in a transformer winding according to claim 1, characterized in that, The current sharing circuit is a common mode inductor composed of a third coil winding provided in the first secondary circuit and a fourth coil winding provided in the second secondary circuit.

3. The power supply for equalizing current in a transformer winding according to claim 2, characterized in that, The first secondary circuit includes a winding internal resistance Ro1, a trace resistance Rc1, diodes D1, D2, D3, and D4. The diodes D1, D2, D3, and D4 form a full bridge circuit, and the diodes D1 and D3 form a first bridge arm, and the diodes D2 and D4 form a second bridge arm. The opposite name end of the first secondary winding is connected to the midpoint of the first bridge arm after being serially connected with the winding internal resistance Ro1, the same name end of the first secondary winding is connected to the midpoint of the second bridge arm, the negative electrodes of the diodes D1 and D2 are connected and then serially connected with the trace resistance Rc1 and connected to one end of the load, and the positive electrodes of the diodes D3 and D4 are connected and then connected to the other end of the load.

4. The power supply for equalizing the current of the transformer winding according to claim 3, characterized in that, The second secondary circuit includes a winding internal resistance Ro2, a trace resistance Rc2, diodes D5, D6, D7, and D8. The diodes D5, D6, D7, and D8 form a full bridge circuit, and the diodes D5 and D7 form a third bridge arm, and the diodes D6 and D8 form a fourth bridge arm. The opposite name end of the second secondary winding is connected to the midpoint of the third bridge arm after being serially connected with the winding internal resistance Ro2, the same name end of the second secondary winding is connected to the midpoint of the fourth bridge arm, the negative electrodes of the diodes D5 and D6 are connected and then serially connected with the trace resistance Rc2 and connected to one end of the load, and the positive electrodes of the diodes D7 and D8 are connected and then connected to the other end of the load.

5. The power supply for equalizing current in a transformer winding according to claim 4, wherein The third coil winding is serially connected between the same name end of the first secondary winding and the midpoint of the second bridge arm, and the same name end of the third coil winding is connected to the same name end of the first secondary winding. The fourth coil winding is serially connected between the opposite name end of the second secondary winding and the winding internal resistance Ro2, and the same name end of the fourth coil winding is connected to the opposite name end of the second secondary winding.

6. The power supply for equalizing the current in the transformer windings according to claim 2, characterized in that, The first secondary circuit includes a winding internal resistance Ro1, a trace resistance Rc1, diodes D1, D2, D3, and D4. The diodes D1, D2, D3, and D4 form a full bridge circuit, and the diodes D1 and D3 form a first bridge arm, and the diodes D2 and D4 form a second bridge arm. The same-named ends of the first secondary winding are connected to the midpoint of the first bridge arm after being serially connected with the winding internal resistance Ro1, and the different-named ends of the first secondary winding are connected to the midpoint of the second bridge arm. The cathodes of the diode D1 and the diode D2 are connected together and then serially connected with the trace resistance Rc1 and connected to one end of the load. The anodes of the diode D3 and the diode D4 are connected together and then connected to the other end of the load.

7. The power supply for equalizing the current of a transformer winding according to claim 6, characterized in that, The second secondary circuit includes a winding internal resistance Ro2, a trace resistance Rc2, a diode D5, a diode D6, a diode D7, and a diode D8; The diode D5, the diode D6, the diode D7, and the diode D8 form a full-bridge circuit, and the diode D5 and the diode D7 form a third bridge arm, and the diode D6 and the diode D8 form a fourth bridge arm; The same-named ends of the second secondary winding are connected to the midpoint of the third bridge arm after being serially connected with the winding internal resistance Ro2, and the different-named ends of the second secondary winding are connected to the midpoint of the fourth bridge arm. The cathodes of the diode D5 and the diode D6 are connected together and then serially connected with the trace resistance Rc2 and connected to one end of the load. The anodes of the diode D7 and the diode D8 are connected together and then connected to the other end of the load.

8. The power supply for equalizing the current of a transformer winding according to claim 7, characterized in that, The third coil winding is serially connected between the different-named end of the first secondary winding and the midpoint of the second bridge arm, and the different-named end of the third coil winding is connected to the different-named end of the first secondary winding; The fourth coil winding is serially connected between the same-named end of the second secondary winding and the winding internal resistance Ro2, and the different-named end of the fourth coil winding is connected to the same-named end of the second secondary winding.

9. An electrical device, characterized in that, A power supply having a transformer winding current sharing as described in any one of claims 1 to 8.

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