A precision multi-channel current-sharing capacitor high temperature load test system

Abstract

The present invention discloses a high temperature load test system for a precise multi-channel current-sharing capacitor, which belongs to the technical field of capacitor high temperature load test, and includes a power module, a plurality of current transformers, a plurality of groups of capacitors to be tested, and a plurality of control switch units. The present invention adopts the secondaries of more than two current transformers to be connected in series and form a loop, so that the current of the primary in the current transformer is consistent. At the same time, since the secondary of the current transformer forms a loop, the current transformer works in a short-circuit state, and the induced voltage at the primary is very small, resulting in very small power consumption of the current transformer, greatly reducing the copper loss and iron loss of the current transformer, making the primary-secondary current ratio of the current transformer more accurate, the current-sharing effect better, and the energy loss smaller.

Description

Technical Field

[0001] The invention relates to the technical field of capacitor high temperature load testing, and in particular to a precise multi-channel current-sharing capacitor high temperature load testing system. Background Art

[0002] High temperature load test is an important part of routine test and identification test of capacitors. It examines the tolerance of capacitors under the combined effects of environmental stress and electrical stress, and is also called durability or service life test.

[0003] The existing test method is to divide the capacitor 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 method uses several transformers, the primary winding of each transformer is connected in series, the first and last ends of the series primary winding are connected to an AC constant current power supply, the two ends of the secondary winding of each transformer are respectively connected to the two ends of the normally open contact of a contactor, the center points of the secondary windings of each transformer are all connected to the positive pole of the same DC power supply, and the negative pole of the DC power supply is connected to the negative pole of the capacitor in series with a resistor.

[0004] The existing test method uses a transformer to provide test current to the capacitor, and the primary winding of the transformer is connected in series to ensure that the current on multiple groups of capacitors is consistent. As a driving source, the transformer must provide sufficient ripple voltage and ripple current for the test capacitor, which makes the power required by the transformer very large, and correspondingly increases the volume and loss of the transformer, and also increases the manufacturing cost. The above problems need to be solved urgently. To this end, a precise multi-channel current-sharing capacitor high-temperature load test system is proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is how to solve the problem in the existing method that the power required by the transformer is very large, which correspondingly increases the volume and loss of the transformer, and provides a precise multi-channel current-sharing capacitor high-temperature load test system.

[0006] The present invention solves the above technical problems through the following technical solutions. The present invention includes a power supply module, multiple current transformers, multiple groups of capacitor groups to be measured, and multiple groups of control switch units; the primary winding of each current transformer is respectively connected in series with two capacitors to be measured in a single group, and the secondary winding of each current transformer is connected end to end to form a loop, so that the current in the primary winding of the current transformer is consistent, and the control switch unit is used to control whether each capacitor group to be measured is connected to the circuit. The power supply module includes an AC output unit, and the ripple voltage and ripple current required by each capacitor to be measured are provided by the AC output unit.

[0007] Furthermore, the number of turns and the physical structure of the primary and secondary windings of each current transformer are the same.

[0008] Furthermore, the AC output unit is implemented by a transformer T, and the two ends of the secondary winding of the transformer T are respectively a first AC output terminal and a second AC output terminal. The power module also includes a DC output unit, and the DC output unit includes a positive terminal and a negative terminal.

[0009] Furthermore, a group of measured capacitors includes two measured capacitors, namely a first measured capacitor and a second measured capacitor, and a group of control switch units includes two control switches, namely a first control switch and a second control switch.

[0010] Furthermore, each current transformer connected to each group of measured capacitor groups includes a first primary winding, a second primary winding, and a secondary winding. One end of the first primary winding is connected to the positive electrode of the first measured capacitor and the first terminal of the first control switch, one end of the second primary winding is connected to the positive electrode of the second measured capacitor and the first terminal of the second control switch, the negative electrodes of the first measured capacitor and the second measured capacitor are connected and then connected to the negative terminal of the DC output unit through a resistor, the other end of the first primary winding is connected to the second terminal of the first control switch, the other end of the second primary winding is connected to the second terminal of the second control switch, the third terminal of the first control switch is connected to the first AC output terminal, the third terminal of the second control switch is connected to the second AC output terminal, and the positive terminal of the DC output unit is connected to the middle point of the secondary winding of the AC output unit through a DC-isolating inductor L; the secondary windings of each current transformer are connected end to end to form a loop.

[0011] Furthermore, each current transformer connected to each group of measured capacitor groups includes a primary winding and a secondary winding, one end of the primary winding is connected to the positive electrode of the first measured capacitor and the first terminal of the first control switch, the other end of the primary winding is connected to the second terminal of the first control switch, the third terminal of the first control switch is connected to the first AC output terminal, the negative electrodes of the first measured capacitor and the second measured capacitor are connected and then connected to the negative terminal of the DC output unit through a resistor, the third terminal of the second control switch is connected to the second AC output terminal, the positive electrode of the second measured capacitor is connected to the second terminal of the second control switch, the first terminal of the second control switch is in an open circuit state, and the positive terminal of the DC output unit is connected to the middle point of the secondary winding of the AC output unit through a DC-isolating inductor L; the secondary windings of each current transformer are connected end to end to form a loop.

[0012] Furthermore, each current transformer connected to each group of measured capacitor groups includes a primary winding with an intermediate tap and a secondary winding, one end of the primary winding is connected to the second terminal of the first control switch, the third terminal of the first control switch is connected to the negative electrode of the first measured capacitor, the positive electrode of the first measured capacitor is connected to the first AC output terminal, the other end of the primary winding is connected to the second terminal of the second control switch, the third terminal of the second control switch is connected to the negative electrode of the second measured capacitor, the positive electrode of the second measured capacitor is connected to the second AC output terminal, the first terminal of the first control switch is connected to the first terminal of the second control switch, the intermediate tap of the primary winding is connected to the negative terminal of the DC output unit through a resistor, and the positive terminal of the DC output unit is connected to the middle point of the secondary winding of the AC output unit through a DC-isolating inductor L; the secondary windings of each current transformer are connected end to end to form a loop.

[0013] Furthermore, the control switch is a contactor having three terminals, namely a first terminal, a second terminal and a third terminal, wherein the second terminal is a common terminal, the first terminal is a normally open terminal, and the third terminal is a normally closed terminal.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] In the present invention, the ripple voltage and ripple current required by the capacitor to be tested are provided by an AC power supply, and the ripple current in each group of capacitors is kept consistent through the regulation of the series-connected current transformer, thereby achieving the purpose of current balancing.

[0016] Since the secondary winding of the current transformer is connected end to end to form a loop, the current transformer works in a short-circuit state, and the induced voltage at the primary end of the current transformer is very small, so that the power consumption of the current transformer is also very small, which greatly reduces the copper loss and iron loss of the current transformer, making the primary-to-secondary current ratio of the current transformer more accurate, the current balancing effect better, and the energy loss smaller; at the same time, it also makes the current transformer smaller in size, lower in manufacturing cost, and saves resources.

[0017] The system can work continuously, and if a certain capacitor under test fails, the failed capacitor under test can be removed from the test without affecting the continued test of other capacitors under test, and the ripple current added to each capacitor under test is consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a high temperature load test system for a precision multi-channel current-sharing capacitor in Embodiment 1 of the present invention;

[0019] Figure 2 It is a structural schematic diagram of a high temperature load test system for a precision multi-channel current-sharing capacitor in a second embodiment of the present invention;

[0020] Figure 3 It is a structural schematic diagram of a high-temperature load test system for a precision multi-channel current-sharing capacitor in Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0021] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0022] Embodiment 1

[0023] like Figure 1 As shown, this embodiment provides a technical solution: a precision multi-channel current-sharing capacitor high-temperature load test system, including a power module, multiple current transformers (T1~nT1, a total of n), multiple groups of measured capacitor groups (1CX1~nCX1 and 1CX2~nCX2, wherein the measured capacitor 1CX1 and the measured capacitor 1CX2 constitute a group of measured capacitor groups, and so on, a total of n groups), and multiple groups of control switch units (the number is 2n, and one measured capacitor corresponds to one control switch); the primary winding of each current transformer is respectively connected in series with two measured capacitors in a single group, and the secondary winding of each current transformer is connected end to end to form a loop, so that the current in the primary winding of the current transformer is consistent, and the control switch unit is used to control whether each measured capacitor group is connected to the circuit, and the power module includes an AC output unit, and the ripple voltage and ripple current required by each measured capacitor are provided by the AC output unit.

[0024] In this embodiment, the number of turns and the physical structure of the primary and secondary windings of each current transformer are the same.

[0025] In this embodiment, the AC output unit is implemented by a transformer T, and the two ends of the secondary winding of the transformer T are respectively a first AC output terminal (AC1) and a second AC output terminal (AC2). The power module also includes a DC output unit, and the DC output unit includes a positive terminal and a negative terminal.

[0026] In this embodiment, a group of measured capacitors includes two measured capacitors, namely a first measured capacitor and a second measured capacitor, and a group of control switch units includes two control switches, namely a first control switch and a second control switch; each current transformer (T1-nT1) connected to each group of measured capacitors includes a first primary winding, a second primary winding, and a secondary winding, and the N2 end of the first primary winding is connected to the positive electrode of the measured capacitor CX1 (the first measured capacitor) and the first terminal (terminal 1) of the first control switch, and the N5 end of the second primary winding is connected to the positive electrode of the measured capacitor CX2 (the second measured capacitor) and the first terminal of the second control switch. The negative electrodes of the capacitors CX1 and CX2 under test are connected and then connected to the negative terminal of the DC output unit through a resistor (R1), the N1 end of the first primary winding is connected to the second terminal (terminal 2) of the first control switch, the N6 end of the second primary winding is connected to the second terminal of the second control switch, the third terminal (terminal 3) of the first control switch is connected to the first AC output terminal, the third terminal of the second control switch is connected to the second AC output terminal, the positive terminal of the DC output unit is connected to the middle point of the secondary winding of the AC output unit through a DC-isolating inductor L; the secondary windings of each current transformer are connected end to end to form a loop.

[0027] In this embodiment, the control switch is a contactor (1J1~nJ1 and 1J2~nJ2, wherein the control switch 1J1 and the control switch 1J2 constitute a group of control switch units, and so on, a total of n groups), the contactor has three terminals, namely a first terminal, a second terminal, and a third terminal, wherein the second terminal is a common terminal, the first terminal is a normally open terminal, and the third terminal is a normally closed terminal.

[0028] Embodiment 2

[0029] like Figure 2 As shown, this embodiment is a first variation of the first embodiment. Different from the structure of the current transformer in the first embodiment, the current transformer in this application has only one primary winding.

[0030] In this embodiment, a group of measured capacitors includes two measured capacitors, namely, a first measured capacitor and a second measured capacitor; a group of control switch units includes two control switches, namely, a first control switch and a second control switch; each current transformer (T1-nT1) connected to each group of measured capacitors includes a primary winding and a secondary winding, the N2 end of the primary winding is connected to the positive electrode of the measured capacitor CX1 (the first measured capacitor) and the first terminal of the first control switch, the N1 end of the primary winding is connected to the second terminal of the first control switch, and the third terminal of the first control switch is connected to the positive electrode of the measured capacitor CX1 (the first measured capacitor). The first AC output terminal is connected, the negative electrodes of the capacitors CX1 and CX2 (the second capacitors) are connected and then connected to the negative terminal of the DC output unit through a resistor (R1), the third terminal of the second control switch is connected to the second AC output terminal, the positive electrode of the capacitor CX2 is connected to the second terminal of the second control switch, the first terminal of the second control switch is in an open circuit state, and the positive terminal of the DC output unit is connected to the middle point of the secondary winding of the AC output unit through a DC-isolating inductor L; the secondary windings of each current transformer are connected end to end to form a loop.

[0031] Except for the above implementation, the other implementations in this embodiment are the same as those in the first embodiment.

[0032] Embodiment 3

[0033] like Figure 3 As shown, this embodiment is a second variation of the first embodiment. Different from the structure of the current transformer in the first embodiment, the current transformer in this application has only one primary winding, and the primary winding has an intermediate tap.

[0034] In this embodiment, a group of measured capacitors includes two measured capacitors, namely a first measured capacitor and a second measured capacitor; a group of control switch units includes two control switches, namely a first control switch and a second control switch; each current transformer (T1-nT1) connected to each group of measured capacitors includes a primary winding with an intermediate tap and a secondary winding, the N1 end of the primary winding is connected to the second terminal of the first control switch, the third terminal of the first control switch is connected to the negative electrode of the measured capacitor CX1, and the positive electrode of the measured capacitor CX1 is connected to the first AC output terminal. The N2 end of the primary winding is connected to the second terminal of the second control switch, the third terminal of the second control switch is connected to the negative electrode of the capacitor CX2 under test, the positive electrode of the capacitor CX2 under test is connected to the second AC output terminal, the first terminal of the first control switch is connected to the first terminal of the second control switch, the N7 end (middle tap) of the primary winding is connected to the negative terminal of the DC output unit through a resistor (R1), and the positive terminal of the DC output unit is connected to the middle point of the secondary winding of the AC output unit through a DC-isolating inductor L; the secondary windings of each current transformer are connected end to end to form a loop.

[0035] Except for the above implementation, the other implementations in this embodiment are the same as those in the first embodiment.

[0036] To sum up, the precision multi-channel current-sharing capacitor high-temperature load test system of the above-mentioned embodiment adopts the secondaries of more than two current transformers to be connected in series end to end and form a loop, so that the primary current in the current transformer is consistent. At the same time, since the secondary of the current transformer forms a loop, the current transformer works in a short-circuit state, and the induced voltage in the primary is very small, resulting in very small power consumption of the current transformer, which greatly reduces the copper loss and iron loss of the current transformer, making the primary-to-secondary current ratio of the current transformer more accurate, the current-sharing effect is better, and the energy loss is smaller.

[0037] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A precision multi-channel current-sharing capacitor high temperature load test system, characterized in that: It includes a power supply module, multiple current transformers, multiple groups of capacitors to be tested, and multiple groups of control switch units; the primary winding of each current transformer is connected in series with two capacitors to be tested in a single group, and the secondary winding of each current transformer is connected end to end to form a loop, so that the current in the primary winding of the current transformer is consistent, and the control switch unit is used to control whether each capacitor group to be tested is connected to the circuit. The power supply module includes an AC output unit, and the ripple voltage and ripple current required by each capacitor to be tested are provided by the AC output unit; The number of turns and physical structure of the primary and secondary windings of each current transformer are the same; The AC output unit is implemented by a transformer T, and the two ends of the secondary winding of the transformer T are respectively a first AC output terminal and a second AC output terminal, and the power module also includes a DC output unit, and the DC output unit includes a positive terminal and a negative terminal; A group of measured capacitors includes two measured capacitors, namely a first measured capacitor and a second measured capacitor, and a group of control switch units includes two control switches, namely a first control switch and a second control switch; Each current transformer connected to each group of measured capacitor groups includes a primary winding and a secondary winding, one end of the primary winding is connected to the positive electrode of the first measured capacitor and the first terminal of the first control switch, the other end of the primary winding is connected to the second terminal of the first control switch, the third terminal of the first control switch is connected to the first AC output terminal, the negative electrodes of the first measured capacitor and the second measured capacitor are connected and then connected to the negative terminal of the DC output unit through a resistor, the third terminal of the second control switch is connected to the second AC output terminal, the positive electrode of the second measured capacitor is connected to the second terminal of the second control switch, the first terminal of the second control switch is in an open circuit state, and the positive terminal of the DC output unit is connected to the middle point of the secondary winding of the AC output unit through a DC-isolating inductor L; the secondary windings of each current transformer are connected end to end to form a loop; The control switch is a contactor having three terminals, namely a first terminal, a second terminal and a third terminal, wherein the second terminal is a common terminal, the first terminal is a normally open terminal, and the third terminal is a normally closed terminal.

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