Alternating current and direct current superposed circuit for capacitor durability test

Abstract

The utility model discloses an AC-DC superposed circuit for a capacitor durability test. The AC-DC superposed circuit comprises an AC power supply, a DC power supply, a DC applying unit, a first tested capacitor and a second tested capacitor. The cathode of the first tested capacitor is connected in series with the cathode of the second tested capacitor. The DC power supply respectively applies DC voltage to the first tested capacitor and the second tested capacitor through the DC applying unit. According to the utility model, an alternating current signal is directly output to the capacitor to be tested, direct current voltage is applied to the capacitor to be tested through an inductor with a center tap or two inductors, and alternating current cannot pass through the inductor according to the principle that direct current is conducted and alternating current is isolated; the direct current is applied to the measured capacitor through the inductor, and no alternating current flows through the inductor, so that the power of the inductor can be very small, the power consumption, the size and the weight are reduced, and the cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of capacitor durability test, in particular to an AC and DC superposition circuit for capacitor durability test. Background Art

[0002] High temperature load test is an important part of routine test and identification test of capacitors. It tests the tolerance of capacitors under the combined effect of environmental stress and electrical stress, and is also called durability or working life test. The existing test method is to divide the capacitors into 11 pairs, each pair consists of 2 capacitors connected in reverse series, apply DC voltage and ripple voltage to each capacitor, and then put it into a high temperature oven for testing. The existing test power supply passes through a transformer with a secondary center tap, the AC power supply is input from the primary of the transformer, the DC signal is input through the center tap of the transformer, and the secondary of the transformer outputs the AC signal. Thus, the superposition of AC and DC is achieved.

[0003] In the prior art solution, a transformer is used to perform AC and DC superposition. The AC signal is transmitted from the primary to the secondary through the transformer, so that the transformer must output all the power, the volume and power consumption of the transformer will be greatly increased, and the cost will also increase significantly. Therefore, an AC and DC superposition circuit for capacitor durability test is proposed. Utility Model Content

[0004] The technical problem to be solved by the utility model is: how to solve the problem that the volume and power consumption of the transformer will be greatly increased and the cost will also increase significantly when using a secondary center-tapped transformer to superimpose AC and DC. An AC and DC superposition circuit for capacitor durability testing is provided.

[0005] The utility model solves the above technical problems through the following technical solutions. The utility model includes an AC power supply, a DC power supply, a DC applying unit, a first capacitor under test, and a second capacitor under test; the negative electrode of the first capacitor under test is connected in series with the negative electrode of the second capacitor under test, the DC power supply applies a DC voltage to the first capacitor under test and the second capacitor under test respectively through the DC applying unit, and the AC power supply is connected to the positive electrodes of the first capacitor under test and the second capacitor under test respectively, and applies an AC voltage to the two capacitors under test.

[0006] Preferably, the AC / DC superposition circuit for capacitor durability test further includes a drift suppression unit, the drift suppression unit is a first inductor, and the DC power supply is connected to the DC application unit through the first inductor.

[0007] Preferably, the first pin and the second pin of the AC power supply are respectively connected to the positive electrodes of the two capacitors to be tested.

[0008] Preferably, the DC application unit includes a second inductor with a center tap, the negative pole of the DC power supply is connected to the negative poles of the two capacitors under test, the positive pole of the DC power supply is connected to the second pin of the first inductor, the first pin of the first inductor is connected to the third pin of the second inductor, the third pin of the second inductor is located on the center tap, and the first pin and the second pin of the second inductor are respectively connected to the positive poles of the two capacitors under test.

[0009] Preferably, the first pin of the second inductor is connected between the second pin of the AC power supply and the positive electrode of the second measured capacitor, and the second pin of the second inductor is connected between the first pin of the AC power supply and the positive electrode of the first measured capacitor.

[0010] Preferably, the DC application unit includes two second inductors connected in sequence, the negative pole of the DC power supply is connected to the negative poles of the two capacitors under test, the positive pole of the DC power supply is connected to the second pin of the first inductor, the first pin of the first inductor is connected to the first pin of the first second inductor and the second pin of the second second inductor, and the second pin of the first second inductor and the first pin of the second second inductor are respectively connected to the positive poles of the two capacitors under test.

[0011] Preferably, the first pin of the second second inductor is connected between the second pin of the AC power supply and the positive electrode of the second measured capacitor, and the second pin of the first second inductor is connected between the first pin of the AC power supply and the positive electrode of the first measured capacitor.

[0012] Compared with the prior art, the utility model has the following advantages: the AC signal is directly output to the capacitor under test, and the DC voltage is applied to the capacitor under test through an inductor with a center tap or two inductors. The principle of the inductor passing DC and blocking AC is utilized, so the AC current cannot pass through, and the DC current is applied to the capacitor under test through the inductor. Since no AC current flows through the inductor, the power of the inductor can be made very small, thereby reducing power consumption, volume and weight, and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of an AC / DC superposition circuit for capacitor durability test in the first embodiment of the utility model;

[0014] Figure 2 It is a structural schematic diagram of an AC / DC superposition circuit for capacitor durability test in the second embodiment of the present utility model. DETAILED DESCRIPTION

[0015] The following is a detailed description of an embodiment of the utility model. This embodiment is implemented on the premise of the technical solution of the utility model, and a detailed implementation method and a specific operation process are given, but the protection scope of the utility model is not limited to the following embodiment.

[0016] Embodiment 1

[0017] like Figure 1 As shown, this embodiment provides a technical solution: an AC / DC superposition circuit for capacitor durability test, comprising an AC power supply AC, a DC power supply DC, an inductor L1 with a center tap (i.e., the second inductor described in the utility model), and two capacitors CX-1 and CX-2 to be tested; the two capacitors CX-1 and CX-2 to be tested are connected in reverse series (the negative poles are connected), and the DC power supply DC applies a DC voltage to the two capacitors CX-1 and CX-2 to be tested that are connected in reverse series through the inductor L1 with a center tap, and the AC power supply AC is respectively connected to the positive poles of the two capacitors CX-1 and CX-2 to be tested, and an AC voltage is applied to the two capacitors CX-1 and CX-2 to be tested.

[0018] In this embodiment, the AC / DC superposition circuit for the capacitor durability test also includes an inductor L2 (i.e., the first inductor described in the present utility model), and the DC power supply DC is connected to the center tap of the inductor L1 through the inductor L2. By connecting the inductor L2 in series in the DC circuit, the midpoint drift caused by the capacity deviation of the capacitors CX-1 and CX-2 under test can be suppressed, so that the AC current applied to the two capacitors CX-1 and CX-2 under test is consistent.

[0019] In this embodiment, the AC / DC superposition circuit for capacitor durability test also includes a DC output negative terminal, the negative electrode of the DC power supply DC is connected to the negative electrodes of the two capacitors CX-1 and CX-2 under test through the DC output negative terminal, the positive electrode of the DC power supply DC is connected to the second pin of the inductor L2, the first pin of the inductor L2 is connected to the third pin of the inductor L1, the third pin of the inductor L1 is located on the center tap, and the first pin and the second pin of the inductor L1 are respectively connected to the positive electrodes of the two capacitors CX-1 and CX-2 under test.

[0020] In this embodiment, the AC / DC superposition circuit for capacitor durability test also includes a first AC output terminal AC1 and a second AC output terminal AC2. The first and second pins of the AC power supply AC are respectively connected to the positive electrodes of the two capacitors CX-1 and CX-2 under test through the first AC output terminal AC1 and the second AC output terminal AC2.

[0021] In this embodiment, the first pin of the inductor L1 is connected between the second pin of the AC power source AC and the second AC output terminal AC2 , and the second pin of the inductor L1 is connected between the first pin of the AC power source AC and the first AC output terminal AC1 .

[0022] In this embodiment, an inductor L1 with a center tap is used. By utilizing the direct current blocking alternating current characteristic of the inductor L1, a direct current power source DC is tapped from the center tap of the inductor L1 and applied to two capacitors to be tested that are connected in series in reverse order through two windings of the inductor, thereby providing a bias voltage for the capacitors. At the same time, by utilizing the direct current blocking alternating current characteristic of the inductor, an alternating current voltage is directly applied to the capacitor to be tested.

[0023] Embodiment 2

[0024] like Figure 2 As shown, this embodiment provides a technical solution: an AC / DC superposition circuit for capacitor durability test, comprising an AC power supply AC, a DC power supply DC, an inductor L1-1, an inductor L1-2 (i.e., the second inductor described in the utility model), and two capacitors CX-1 and CX-2 to be tested; the negative electrodes of the two capacitors CX-1 and CX-2 to be tested are connected in reverse series, and the DC power supply DC applies a DC voltage to the two capacitors CX-1 and CX-2 to be tested in reverse series through the inductor L1-1 and the inductor L1-2 respectively, and the AC power supply AC is connected to the positive electrodes of the two capacitors CX-1 and CX-2 to be tested respectively, and applies an AC voltage to the two capacitors CX-1 and CX-2 to be tested.

[0025] In this embodiment, the AC / DC superposition circuit for the capacitor durability test also includes an inductor L2 (i.e., the first inductor described in the present utility model), and the DC power supply DC is connected between the inductor L1-1 and the inductor L1-2 through the inductor L2. By connecting the inductor L2 in series in the DC circuit, the midpoint drift caused by the capacity deviation of the capacitors CX-1 and CX-2 under test can be suppressed, so that the AC current applied to the two capacitors CX-1 and CX-2 under test is consistent.

[0026] In this embodiment, the AC / DC superposition circuit for capacitor durability test also includes a DC output negative terminal, the negative electrode of the DC power supply DC is connected to the negative electrodes of the two capacitors CX-1 and CX-2 under test through the DC output negative terminal, the positive electrode of the DC power supply DC is connected to the second pin of the inductor L2, the first pin of the inductor L2 is connected to the first pin of the inductor L1-1 and the second pin of the inductor L1-2, the second pin of the inductor L1-1 and the first pin of the inductor L1-2 are respectively connected to the positive electrodes of the two capacitors CX-1 and CX-2 under test.

[0027] In this embodiment, the AC / DC superposition circuit for capacitor durability test also includes a first AC output terminal AC1 and a second AC output terminal AC2. The first and second pins of the AC power supply AC are respectively connected to the positive electrodes of the two capacitors CX-1 and CX-2 under test through the first AC output terminal AC1 and the second AC output terminal AC2.

[0028] In this embodiment, the first pin of the inductor L1 - 2 is connected between the second pin of the AC power source AC and the second AC output terminal AC2 , and the second pin of the inductor L1 - 1 is connected between the first pin of the AC power source AC and the first AC output terminal AC1 .

[0029] In summary, the capacitor durability test uses an AC / DC superposition circuit, and the AC signal is directly output to the capacitor under test. The DC voltage is applied to the capacitor under test through an inductor with a center tap or two inductors. The principle of inductors passing DC and blocking AC is used, so AC current cannot pass through, and DC current is applied to the capacitor under test through the inductor. Since no AC current flows through the inductor, the power of the inductor can be made very small, reducing power consumption, volume and weight, and reducing costs.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0032] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An AC / DC superposition circuit for capacitor durability test, characterized in that: It includes an AC power supply, a DC power supply, a DC applying unit, a first capacitor under test, and a second capacitor under test; the negative electrode of the first capacitor under test is connected in series with the negative electrode of the second capacitor under test, the DC power supply applies a DC voltage to the first capacitor under test and the second capacitor under test respectively through the DC applying unit, and the AC power supply is connected to the positive electrodes of the first capacitor under test and the second capacitor under test respectively, and applies an AC voltage to the two capacitors under test.

2. The AC / DC superposition circuit for capacitor durability test according to claim 1, characterized in that: The AC / DC superposition circuit for capacitor durability test further includes a drift suppression unit, which is a first inductor, and the DC power supply is connected to the DC application unit through the first inductor.

3. The AC / DC superposition circuit for capacitor durability test according to claim 1, characterized in that: The first pin and the second pin of the AC power supply are respectively connected to the positive electrodes of the two capacitors to be tested.

4. The AC / DC superposition circuit for capacitor durability test according to claim 1, characterized in that: The DC application unit includes a second inductor with a center tap, the negative electrode of the DC power supply is connected to the negative electrodes of the two capacitors under test, the positive electrode of the DC power supply is connected to the second pin of the first inductor, the first pin of the first inductor is connected to the third pin of the second inductor, the third pin of the second inductor is located on the center tap, and the first pin and the second pin of the second inductor are respectively connected to the positive electrodes of the two capacitors under test.

5. The AC / DC superposition circuit for capacitor durability test according to claim 4, characterized in that: The first pin of the second inductor is connected between the second pin of the AC power supply and the positive electrode of the second measured capacitor, and the second pin of the second inductor is connected between the first pin of the AC power supply and the positive electrode of the first measured capacitor.

6. The AC / DC superposition circuit for capacitor durability test according to claim 1, characterized in that: The DC application unit includes two second inductors connected in sequence, the negative electrode of the DC power supply is connected to the negative electrodes of the two capacitors under test, the positive electrode of the DC power supply is connected to the second pin of the first inductor, the first pin of the first inductor is connected to the first pin of the first second inductor and the second pin of the second second inductor, and the second pin of the first second inductor and the first pin of the second second inductor are respectively connected to the positive electrodes of the two capacitors under test.

7. The AC / DC superposition circuit for capacitor durability test according to claim 6, characterized in that: The first leg of the second second inductor is connected between the second leg of the AC power supply and the positive electrode of the second capacitor under test, and the second leg of the first second inductor is connected between the first leg of the AC power supply and the positive electrode of the first capacitor under test.

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