Controllable three-phase AC power capacitor reliability test circuit, method and system

Abstract

The invention discloses a controllable three-phase AC power capacitor reliability test circuit, method and system, and the circuit comprises a first DC voltage source, a second DC voltage source, a three-phase inverter, a first transformer, a second transformer, a third transformer, a first inductor, a second inductor, and a third inductor. The output end of the first DC voltage source is connected with the input end of the three-phase inverter, and the three-phase inverter is connected with the first end of the first to-be-tested capacitor, the first end of the second to-be-tested capacitor and the first end of the third to-be-tested capacitor through the first transformer, the second transformer and the third transformer. The second ends of the first to-be-measured capacitor, the second to-be-measured capacitor and the third to-be-measured capacitor are connected to the positive electrode of the second direct-current voltage source through the first inductor, the second inductor and the third inductor respectively, and the negative electrode of the second direct-current voltage source is connected with the negative electrode of the first direct-current voltage source. The method is low in cost, low in energy consumption and convenient to control.

Description

Technical Field

[0001] The present invention relates to capacitor testing technology, and in particular to a controllable three-phase AC power capacitor reliability testing circuit, method and system. Background Art

[0002] There is little research on existing AC power capacitor testing technology, and there are still some deficiencies in practical application. Existing technologies can be divided into three categories:

[0003] (1) Direct test type: This type of test technology directly uses a high-voltage DC voltage source and an AC voltage source to provide a DC bias voltage and an AC ripple voltage for the capacitor under test. This type of method has simple topology and control, but has high hardware costs and low control flexibility, and can only be applied to a specific capacitor device;

[0004] (2) Single-phase load type: This type of test method can only test a single power capacitor, which is difficult to expand. At the same time, this method requires a resistive load, which will consume most of the power;

[0005] (3) Three-phase reactive cycle type: This test method is an upgrade from the first type and can simultaneously test the reliability of three AC power capacitors. However, this method requires a high-voltage DC voltage source and an AC current source, which are expensive. In addition, this method cannot control ripple voltage and current, making it very inconvenient to use.

[0006] In summary, the existing AC power capacitor testing technology has the disadvantages of high cost, high energy consumption, and inconvenient control. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a controllable three-phase AC power capacitor reliability test circuit, method and system with low cost, low energy consumption and convenient control.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] A controllable three-phase AC power capacitor reliability test circuit includes a first DC voltage source, a second DC voltage source, a three-phase inverter, a first transformer, a second transformer, a third transformer, a first inductor, a second inductor, and a third inductor, wherein the output end of the first DC voltage source is connected to the input end of the three-phase inverter, the first output end of the three-phase inverter is connected to the first end of a first capacitor to be tested through a first transformer, the second output end of the three-phase inverter is connected to the first end of a second capacitor to be tested through a second transformer, the third output end of the three-phase inverter is connected to the first end of a third capacitor to be tested through a third transformer, the second ends of the first capacitor to be tested, the second ends of the third capacitor to be tested are connected to the positive electrode of the second DC voltage source through the first inductor, the second inductor, and the third inductor, respectively, and the negative electrode of the second DC voltage source is connected to the negative electrode of the first DC voltage source.

[0010] Furthermore, it also includes a first voltage-stabilizing capacitor, which is connected in parallel with the first DC voltage source.

[0011] Furthermore, it includes a second voltage-stabilizing capacitor, which is connected in parallel with the second DC voltage source.

[0012] Furthermore, the first DC voltage source is a low-voltage DC voltage source, and the second DC voltage source is a low-voltage DC voltage source.

[0013] Furthermore, the first transformer, the second transformer, and the third transformer are all transformers with adjustable transformation ratios.

[0014] Furthermore, the first DC voltage source provides ripple voltage and current to the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured, and the amplitude of the ripple voltage and current is changed by adjusting the transformation ratio of the first transformer, the second transformer, and the third transformer.

[0015] Furthermore, the three-phase inverter is a DC-AC inverter.

[0016] A controllable three-phase AC power capacitor reliability test method is implemented based on the above-mentioned controllable three-phase AC power capacitor reliability test circuit, and the method includes:

[0017] S1, the controller sends a control instruction to the first DC voltage source and the second DC voltage source to turn on the first DC voltage source and the second DC voltage source;

[0018] S2. The controller sends a control instruction to the three-phase inverter, so that the three-phase inverter outputs a three-phase AC voltage signal;

[0019] S3, the three-phase AC voltage signal reaches the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured respectively through the first transformer, the second transformer, and the third transformer, providing ripple voltage and current for the capacitors to be measured; the second DC voltage source provides a DC bias voltage for all the capacitors to be measured;

[0020] S4, measuring the voltage and current of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times respectively;

[0021] S5. Calculate the capacitance and equivalent series resistance of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times based on the measured voltages and currents of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured;

[0022] S6. Determine the aging degree of the capacitors and evaluate the reliability of the capacitors based on the capacitance values and equivalent series resistance values of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times.

[0023] A controllable three-phase AC power capacitor reliability test system includes the above-mentioned controllable three-phase AC power capacitor reliability test circuit, and further includes:

[0024] a controller configured to send control instructions to the first DC voltage source and the second DC voltage source to turn on the first DC voltage source and the second DC voltage source; and to send control instructions to the three-phase inverter to cause the three-phase inverter to output a three-phase AC voltage signal;

[0025] A sampler, configured to measure the voltage and current of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times;

[0026] The calculation module is used to calculate the capacitance and equivalent series resistance of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times based on the measured voltages and currents of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured, so as to determine the degree of capacitor aging and evaluate the capacitor reliability.

[0027] Compared with the existing technology, the present invention has the following advantages: starting from practical applications, the present invention comprehensively considers the operating mode of three-phase AC power capacitors in real applications, and proposes a new and controllable three-phase AC power capacitor reliability impact testing technology, which can solve the following core technical problems:

[0028] 1) Three three-phase AC power capacitors can be tested simultaneously, greatly improving the test efficiency;

[0029] 2) The working conditions of all capacitors to be tested can be freely configured according to actual needs without changing the hardware, making the control very convenient;

[0030] 3) The voltage source of the present invention can be a low-voltage voltage source, which is low in cost and greatly reduces the cost and difficulty of industrial application;

[0031] 4) No need to connect load, low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 1 is a circuit diagram of a controllable three-phase AC power capacitor reliability test circuit provided by an embodiment of the present invention;

[0033] Figure 2 This is a simulation circuit diagram of a controllable three-phase AC power capacitor reliability test system provided by an embodiment of the present invention;

[0034] Figure 3 2 is a diagram of simulation results of an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0036] The embodiment of the present invention provides a controllable three-phase AC power capacitor reliability test circuit, such as Figure 1 As shown, it includes a first DC voltage source V1, a second DC voltage source V2, a three-phase inverter Inverter, a first transformer T1, a second transformer T2, a third transformer T3, a first inductor L1, a second inductor L2, a third inductor L3, a first voltage-stabilizing capacitor Cv1, and a second voltage-stabilizing capacitor Cv2, wherein the output end of the first DC voltage source V1 is connected to the input end of the three-phase inverter Inverter, and the first output end of the three-phase inverter Inverter is connected to the first to-be-tested terminal through the first transformer T1. The first end of capacitor C1 and the second output end of the three-phase inverter are connected to the first end of a second capacitor to be tested C2 via a second transformer T2. The third output end of the three-phase inverter is connected to the first end of a third capacitor to be tested C3 via a third transformer T3. The second ends of the first capacitor to be tested C1, the second capacitor to be tested C2, and the third capacitor to be tested C3 are connected to the positive electrode of a second DC voltage source V2 via a first inductor, a second inductor, and a third inductor, respectively. The negative electrode of the second DC voltage source V2 is connected to the negative electrode of the first DC voltage source V1. The first voltage-stabilizing capacitor Cv1 is connected in parallel with the first DC voltage source V1. The second voltage-stabilizing capacitor Cv2 is connected in parallel with the second DC voltage source V2.

[0037] The first DC voltage source V1 and the second DC voltage source V2 are low-voltage DC voltage sources. The first transformer T1, the second transformer T2, and the third transformer T3 are all transformers with adjustable transformation ratios. The first DC voltage source V1 provides ripple voltage and current to the first capacitor C1, the second capacitor C2, and the third capacitor C3 to be tested. The amplitude of the ripple voltage and current is changed by adjusting the transformation ratios of the first transformer T1, the second transformer T2, and the third transformer T3. The three-phase inverter is a DC-AC inverter.

[0038] In the present invention, the first DC voltage source V1 is used to output a stable DC voltage, CV1 and CV2 are mainly used for voltage stabilization, increasing the stability of the output voltages of V1 and V2; the three-phase inverter can convert the DC voltage into a three-phase AC voltage signal, which is then isolated and stepped up / down through transformers T1 / T2 / T3 and applied to the capacitor to be tested to provide ripple voltage and current; inductors L1, L2, and L3 are mainly used for AC filtering to prevent AC signals from entering the DC voltage source V2 and affecting the normal operation of the voltage source; V2 mainly provides a stable voltage signal, and the inductor L, capacitor CV2, and power supply V2 provide a controllable high-voltage DC bias voltage for the capacitor to be tested, and the bias voltage amplitude can be achieved by controlling V2. The power supply V1, capacitor CV1, and three-phase inverter can provide ripple voltage and current for the capacitor to be tested. The three-phase inverter can achieve free control of the frequency and phase of the ripple voltage and current through double closed-loop control.

[0039] The present invention can test three AC power capacitors simultaneously without any load and with very low power consumption. It also features multi-degree-of-freedom control, meaning the DC bias voltage, ripple voltage, and ripple current of the capacitors being tested can be freely configured. The ripple voltage and current frequencies can be modulated by changing the control parameters within the inverter, conveniently matching the operating conditions of the capacitors being tested. The present invention only requires a low-voltage DC voltage source, significantly reducing costs.

[0040] An embodiment of the present invention further provides a controllable three-phase AC power capacitor reliability test method, which is implemented based on the above-mentioned controllable three-phase AC power capacitor reliability test circuit, and includes:

[0041] S1. The controller sends a control instruction to the first DC voltage source and the second DC voltage source to turn on the first DC voltage source and the second DC voltage source, and configures the DC voltage amplitude, thereby outputting a stable DC voltage to the three-phase inverter;

[0042] S2. The controller sends a control instruction to the three-phase inverter, causing the three-phase inverter to output a three-phase AC voltage signal. Specifically, the controller provides dual closed-loop control for the three-phase inverter, mainly sending PWM signals to control the six switching devices in the three-phase inverter, causing the three-phase inverter to output a three-phase AC voltage signal.

[0043] S3, the three-phase AC voltage signal reaches the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured respectively through the first transformer, the second transformer, and the third transformer, providing ripple voltage and current for the capacitors to be measured; the second DC voltage source provides a DC bias voltage for all the capacitors to be measured;

[0044] S4, measuring the voltage and current of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times respectively;

[0045] S5. Calculate the capacitance and equivalent series resistance of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times based on the measured voltages and currents of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured;

[0046] S6. Determine the capacitor aging degree and evaluate the capacitor reliability based on the capacitance and equivalent series resistance values of the first, second, and third capacitors at different times. Methods for determining the capacitor aging degree and evaluating the capacitor reliability based on the capacitance and equivalent series resistance values are prior art and are not further described.

[0047] An embodiment of the present invention further provides a controllable three-phase AC power capacitor reliability testing system, comprising the above-mentioned controllable three-phase AC power capacitor reliability testing circuit, and further comprising:

[0048] a controller configured to send control instructions to the first DC voltage source and the second DC voltage source to turn on the first DC voltage source and the second DC voltage source; and to send control instructions to the three-phase inverter to cause the three-phase inverter to output a three-phase AC voltage signal;

[0049] A sampler, configured to measure the voltage and current of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times;

[0050] The calculation module is used to calculate the capacitance and equivalent series resistance of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times based on the measured voltages and currents of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured, so as to determine the degree of capacitor aging and evaluate the capacitor reliability.

[0051] The present invention is simulated and tested, and the simulation test circuit diagram is as follows: Figure 2As shown in the figure, the test conditions are: DC bias voltage is set to 100V, AC ripple voltage is set to 200V. The voltage value of the capacitor under test is as follows: Figure 3 As shown in the figure, the voltage of the capacitor being measured can be changed by changing the control.

[0052] It should be noted that, in this document, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0053] It should be understood that the above embodiments and descriptions only describe the principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A controllable three-phase AC power capacitor reliability test circuit, characterized by: The invention comprises a first DC voltage source, a second DC voltage source, a three-phase inverter, a first transformer, a second transformer, a third transformer, a first inductor, a second inductor, and a third inductor, wherein the output end of the first DC voltage source is connected to the input end of the three-phase inverter, the first output end of the three-phase inverter is connected to the first end of the first capacitor to be measured through the first transformer, the second output end of the three-phase inverter is connected to the first end of the second capacitor to be measured through the second transformer, the third output end of the three-phase inverter is connected to the first end of the third capacitor to be measured through the third transformer, the second ends of the first capacitor to be measured, the second ends of the third capacitor to be measured are connected to the positive electrode of the second DC voltage source through the first inductor, the second inductor, and the third inductor respectively, and the negative electrode of the second DC voltage source is connected to the negative electrode of the first DC voltage source.

2. The controllable three-phase AC power capacitor reliability test circuit according to claim 1, characterized in that: It also includes a first voltage-stabilizing capacitor, which is connected in parallel with the first DC voltage source.

3. The controllable three-phase AC power capacitor reliability test circuit according to claim 1, characterized in that: It also includes a second voltage-stabilizing capacitor, which is connected in parallel with the second DC voltage source.

4. The controllable three-phase AC power capacitor reliability test circuit according to claim 1, characterized in that: The first DC voltage source is a low-voltage DC voltage source.

5. The controllable three-phase AC power capacitor reliability test circuit according to claim 1, characterized in that: The second DC voltage source is a low-voltage DC voltage source.

6. The controllable three-phase AC power capacitor reliability test circuit according to claim 1, characterized in that: The first transformer, the second transformer and the third transformer are all transformers with adjustable transformation ratios.

7. The controllable three-phase AC power capacitor reliability test circuit according to claim 6, characterized in that: The first DC voltage source provides ripple voltage and current to the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured, and the amplitude of the ripple voltage and current is changed by adjusting the transformation ratio of the first transformer, the second transformer, and the third transformer.

8. The controllable three-phase AC power capacitor reliability test circuit according to claim 1, characterized in that: The three-phase inverter is a DC-AC inverter.

9. A controllable three-phase AC power capacitor reliability testing method, characterized by: The method is implemented based on the controllable three-phase AC power capacitor reliability test circuit according to claim 1, and the method includes: S1, the controller sends a control instruction to the first DC voltage source and the second DC voltage source to turn on the first DC voltage source and the second DC voltage source; S2. The controller sends a control instruction to the three-phase inverter, so that the three-phase inverter outputs a three-phase AC voltage signal; S3, the three-phase AC voltage signal reaches the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured respectively through the first transformer, the second transformer, and the third transformer, providing ripple voltage and current for the capacitors to be measured; the second DC voltage source provides a DC bias voltage for all the capacitors to be measured; S4, measuring the voltage and current of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times respectively; S5. Calculate the capacitance and equivalent series resistance of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times based on the measured voltages and currents of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured; S6. Determine the aging degree of the capacitors and evaluate the reliability of the capacitors based on the capacitance values and equivalent series resistance values of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times.

10. A controllable three-phase AC power capacitor reliability test system, characterized by: The controllable three-phase AC power capacitor reliability test circuit according to claim 1 further comprises: a controller configured to send control instructions to the first DC voltage source and the second DC voltage source to turn on the first DC voltage source and the second DC voltage source; and to send control instructions to the three-phase inverter to cause the three-phase inverter to output a three-phase AC voltage signal; A sampler, configured to measure the voltage and current of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times; The calculation module is used to calculate the capacitance and equivalent series resistance of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured at different times based on the measured voltages and currents of the first capacitor to be measured, the second capacitor to be measured, and the third capacitor to be measured, so as to determine the degree of capacitor aging and evaluate the capacitor reliability.

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