High-frequency alternating current test equipment and method based on switching tube

Abstract

The invention belongs to the field of alternating-current testing, particularly relates to high-frequency alternating-current testing equipment and method based on a switching tube, and mainly solves the technical problems that existing alternating-current testing equipment is low in output frequency, complex, low in cost performance and the like. The equipment comprises a switching tube K1, a switching tube K2, a control drive circuit, a direct-current power supply DC, an inductor L, a capacitor C and a measuring device. By utilizing the high-frequency switching characteristic of the switching tube and the LC resonance principle, the tested product is connected in series into the test equipment, and the high-frequency current is simply and conveniently applied to the tested product, so that the characteristics of impedance, temperature rise and the like of the tested product under the high-frequency current are obtained; the actual performance of the material under the corresponding frequency can be better verified in advance during model selection, so that various anomalies such as impedance and temperature rise caused by high working frequency of a circuit in the later stage of design are solved.

Description

Technical Field

[0001] The present invention relates to an AC test device, and particularly to a high-frequency AC test device and method based on a switching tube. Background Art

[0002] With the application and development of power electronics technology in various fields such as industry, medical treatment, communication, and scientific research, and the replacement of new materials such as MOSFET and IGBT, the switching frequency of power electronics has been further increased, usually in the range of kHz to MHz. The equivalent states and parameters of common capacitors, inductors, wires, etc. at high frequencies are completely different from those at DC or low frequencies. Therefore, higher requirements are imposed on the high-frequency characteristics of the devices and materials used in the equipment. The equivalent capacitance, equivalent inductance, ESR, etc. of devices such as inductors, capacitors, and wires in the circuit at high frequencies will have an important impact on the working state of the circuit. Therefore, it is very crucial to evaluate the characteristics of the devices and materials used at high frequencies during design and selection.

[0003] Existing AC test devices usually have an output frequency of about 2 kHz to 5 kHz, which is difficult to meet the current high-frequency requirements, and have disadvantages such as complex equipment and low cost performance. Therefore, it is urgent to invent a test method and device with simple principle, high cost performance, and wide frequency range. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problems of existing AC test devices such as low output frequency, complex equipment, and low cost performance, and to provide a high-frequency AC test device and method based on a switching tube.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A high-frequency AC test device based on a switching tube, which is characterized in that:

[0007] It includes a switching tube K1, a switching tube K2, a control and drive circuit, a DC power supply DC, an inductor L, a capacitor C, and a test device;

[0008] The control ends of the switching tube K1 and the switching tube K2 are respectively connected to the two output ends of the control and drive circuit; one end of the switching tube K1 is connected to the positive pole of the DC power supply DC, and one end of the switching tube K2 is respectively connected to the negative pole of the DC power supply DC and serves as a connection node A;

[0009] The two output ends of the control and drive circuit are used to respectively output control signals to the control ends of the switching tube K1 and the switching tube K2, and control the switching tube K1 and the switching tube K2 to conduct alternately at a frequency f and a duty cycle of 50%, so as to generate a square wave signal with a frequency of f, an amplitude of U, and a duty cycle of 50%; the DC power supply DC is a DC power supply with adjustable voltage, and is used to provide a voltage to control the amplitude U of the square wave signal;

[0010] The other end of switching transistor K1 is connected to the other end of switching transistor K2, and serves as connection node B;

[0011] When the DUT is not an inductor or a capacitor, one end of inductor L is connected to the other end of switching transistor K1, one end of capacitor C is connected to one end of switching transistor K2, and the other ends of inductor L and capacitor C are respectively connected to both ends of the DUT; Inductor L and capacitor C form an LC resonance circuit;

[0012] When the DUT is an inductor, the other end of switching transistor K1 is connected to one end of the DUT, one end of capacitor C is connected to one end of switching transistor K2, and the other end is connected to the other end of the DUT; The DUT and capacitor C form an LC resonance circuit;

[0013] When the DUT is a capacitor, one end of inductor L is connected to the other end of switching transistor K1, the other end of inductor L is connected to one end of the DUT, and the other end of the DUT is connected to one end of switching transistor K2; Inductor L and the DUT form an LC resonance circuit.

[0014] Further, both switching transistor K1 and switching transistor K2 are NMOS transistors, and the control driving circuit is an NMOS control driving circuit;

[0015] The gates of switching transistor K1 and switching transistor K2 are respectively connected to two output terminals of the control driving circuit;

[0016] The drain of switching transistor K1 is connected to the positive pole of DC power supply DC, and the source of switching transistor K2 is connected to the negative pole of DC power supply DC, and serves as connection node A;

[0017] The source of switching transistor K1 is connected to the drain of switching transistor K2, and serves as connection node A.

[0018] Further, the output frequency of the control driving circuit is adjustable.

[0019] Meanwhile, the present invention also provides a high-frequency AC testing method based on switching transistors, which uses the aforementioned high-frequency AC testing equipment based on switching transistors, and is characterized in that it includes the following steps:

[0020] Step 1, Connect the DUT in a high-frequency AC testing equipment based on switching transistors according to the testing requirements;

[0021] Step 2, Determine the frequency f output by the control driving circuit according to the testing requirements;

[0022] Step 3, Determine the inductance value of inductor L and / or the capacitance value of capacitor C according to the testing requirements;

[0023] Step 4: Control switch tube K1 and switch tube K2 to conduct alternately at a frequency f and a duty cycle of 50% according to the corresponding control signals, generating a square wave signal with a frequency of f, an amplitude of U, and a duty cycle of 50%, so as to generate a high-frequency, sinusoidal waveform resonance current on the resonance loop.

[0024] Step 5: Adjust the voltage of the DC power supply DC, thereby adjusting the amplitude U of the resonance current, so that the magnitude of the resonance current flowing through the DUT meets the test requirements, measure the working state of the DUT under this resonance current, and complete the test.

[0025] Further, in step 3, according to the frequency f required by the test, the inductance value of the inductor L and / or the capacitance value of the capacitor C are calculated using the following formula:

[0026] f = 1 / 2π√(lc);

[0027] In the formula: l and c are respectively the inductance value of the inductor L and the capacitance value of the capacitor C, or the inductance value of the inductor L and the capacitance value of the DUT, or the inductance value of the DUT and the capacitance value of the capacitor C.

[0028] Further, step 5 also includes continuously increasing the voltage provided by the DC power supply DC and measuring the working state of the DUT under the limit resonance current.

[0029] The beneficial effects of the present invention are:

[0030] By utilizing the high-frequency switching characteristics of the switch tubes and the LC resonance principle, the present invention connects the DUT in series into the test equipment, simply and conveniently applies a high-frequency current to the DUT, thereby obtaining the impedance, temperature rise and other characteristics of the DUT under the high-frequency current, realizing better pre-verification of the actual performance of the material at the corresponding frequency during the selection, and thus solving various anomalies such as impedance and temperature rise caused by the high circuit operating frequency in the later stage of design. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic structural diagram of Embodiment 1 of the present invention;

[0032] Figure 2 is a schematic structural diagram of Embodiment 2 of the present invention;

[0033] Figure 3 is a schematic structural diagram of Embodiment 3 of the present invention;

[0034] Figure 4 is a waveform diagram of the current and voltage flowing through the capacitor in Embodiment 1 of the present invention;

[0035] Figure 5 is at Figure 4 Based on the above, after further increasing the output voltage of the DC power supply DC, it is a waveform diagram of the current and voltage flowing through the capacitor. Specific Embodiments

[0036] To make the objectives, advantages and features of the present invention clearer, the following further details the high-frequency AC test equipment and method based on a switching tube proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following specific embodiments, the advantages and features of the present invention will be clearer.

[0037] Embodiment 1

[0038] Refer to Figure 1 , a high-frequency AC test equipment based on a switching tube in this embodiment includes a switching tube K1, a switching tube K2, a control driving circuit, a DC power supply DC, an inductor L, a capacitor C, and a test device.

[0039] Among them, both the switching tube K1 and the switching tube K2 are NMOS tubes, and the control driving circuit adopts an existing mature NMOS control driving circuit with adjustable frequency. The gates of the switching tube K1 and the switching tube K2 are respectively connected to the two output terminals of the control driving circuit; the drain of the switching tube K1 is connected to the positive pole of the DC power supply DC, and the source of the switching tube K2 is respectively connected to the negative pole of the DC power supply DC and one end of the capacitor C; the source of the switching tube K1 is connected to the drain of the switching tube K2 and is connected to one end of the inductor L; the other end of the inductor L and the other end of the capacitor C are connected to each other.

[0040] The DC power supply DC is a DC power supply with adjustable voltage. The two output terminals of the control driving circuit respectively output control signals to the gates of the switching tube K1 and the switching tube K2, so that the switching tube K1 and the switching tube K2 are alternately turned on in a manner of frequency f and duty cycle 50% under the control of the corresponding control signals, thereby generating a square wave signal with frequency f, amplitude U, and duty cycle 50%, and the amplitude of this square wave signal is controlled by the voltage provided by the DC power supply DC.

[0041] By connecting the test terminal of the test device to the capacitor C, it can be measured to obtain the working parameters.

[0042] Existing design selection requirements: Capacitor C, designed capacity 2 μF, designed ripple current 4.5 A @ 100 kHz, verify the working characteristics of a certain manufacturer's capacitor at 4.5 A @ 100 kHz.

[0043] The test method steps are as follows:

[0044] S1. According to the test requirements, connect the above circuit and use the capacitor C as the tested product.

[0045] S2. Select 100 kHz as the frequency f output by the control driving circuit, that is, the resonance frequency of LC in the circuit is 100 kHz.

[0046] S3. According to the frequency f = 100 kHz required by the test, the inductance value of the inductor L is calculated to be 1.26 μH using the following formula:

[0047] f = 1 / (2π√(LC));

[0048] In the formula: L and C are the inductance value of the inductor L and the capacitance value of the capacitor C, respectively.

[0049] S4. Control the drive circuit to start working, and control the switching transistors K1 and K2 to conduct alternately at a frequency of f and a duty cycle of 50% according to the corresponding control signals, generating a square wave signal with a frequency of f, an amplitude U, and a duty cycle of 50%, so as to generate a high-frequency, sinusoidal waveform resonance current with a frequency of f, an amplitude U, and a duty cycle of 50% on the LC resonance loop composed of the inductor L and the capacitor C. This resonance current is a high-frequency ripple current with an amplitude U controlled by the input voltage and a frequency controlled by the switching transistor frequency.

[0050] S5. Gradually increase the voltage output by the DC power supply DC from 0 V until the resonance current flowing through the capacitor C reaches 4.5 A, and measure the operating parameters of the capacitor C in this state through the measuring device, thereby completing the test. Of course, according to the actual test requirements, the voltage can also be continuously increased to make the resonance current continue to increase to test the limit parameters of the capacitor.

[0051] See Figure 4 and Figure 5 , in the figure, the waveform of ① is the waveform of the current flowing through the capacitor, and the waveform of ② is the waveform of the voltage across the capacitor. It can be seen that Figure 4 compared with the prior art, the test equipment of this embodiment can output a higher frequency of high-frequency current, Figure 4 which is 100 kHz in Figure 5 and the increase in the current value is achieved by adjusting the output voltage of the DC power supply DC on the basis of Figure 4 .

[0052] Embodiment 2

[0053] See Figure 2 , the difference between this embodiment and Embodiment 1 is that the inductor L is used as the tested product. During the specific test, according to the required inductor L of the test, the capacitance value of the capacitor C is determined in the same manner as in Embodiment 1, and the magnitude of the resonance current flowing through the inductor L is measured. Other contents of this embodiment are the same as those of Embodiment 1.

[0054] Embodiment 3

[0055] See Figure 3, The difference between this embodiment and Embodiment 1 is that the tested product in this embodiment is a non-capacitor and inductor component, and this tested product is connected to the other ends of the inductor L and the capacitor C. During the test, calculate the matching values of the inductor L and the capacitor C in the same way as in Embodiment 1, select the appropriate corresponding inductor L and capacitor C according to the required frequency, and measure the magnitude of the resonant current flowing through the tested product. Other contents of this embodiment are the same as those of Embodiment 1.

Claims

1. A high-frequency AC test device based on a switching tube, characterized by: It includes a switch tube K1, a switch tube K2, a control drive circuit, a DC power supply DC, an inductor L, a capacitor C and a test device; The control ends of the switch tube K1 and the switch tube K2 are respectively connected to the two output ends of the control drive circuit; one end of the switch tube K1 is connected to the positive electrode of the DC power supply DC, and one end of the switch tube K2 is connected to the negative electrode of the DC power supply DC, and serves as a connection node A; The two output terminals of the control drive circuit are used to output control signals to the control terminals of the switch tube K1 and the switch tube K2, respectively, to control the switch tube K1 and the switch tube K2 to be alternately turned on at a frequency f and a duty cycle of 50%, thereby generating a square wave signal with a frequency f, an amplitude U, and a duty cycle of 50%. The DC power supply DC is a DC power supply with adjustable voltage, and is used to provide a voltage to control the amplitude U of the square wave signal. The other end of the switch tube K1 is connected to the other end of the switch tube K2 and serves as a connection node B; When the product under test is not an inductor or capacitor, one end of the inductor L is connected to the other end of the switch tube K1, one end of the capacitor C is connected to one end of the switch tube K2, and the other end of the inductor L and the other end of the capacitor C are respectively connected to the two ends of the product under test; the inductor L and the capacitor C form an LC resonant circuit; When the DUT is an inductor, the other end of the switch tube K1 is connected to one end of the DUT, one end of the capacitor C is connected to one end of the switch tube K2, and the other end is connected to the other end of the DUT; the DUT and capacitor C form an LC resonant circuit; When the product under test is a capacitor, one end of the inductor L is connected to the other end of the switch tube K1, the other end of the inductor L is connected to one end of the product under test, and the other end of the product under test is connected to one end of the switch tube K2; the inductor L and the product under test form an LC resonant circuit; The test end of the test device is connected to the product under test to obtain required working parameters.

2. The high-frequency AC test equipment based on a switching tube according to claim 1, characterized in that: The switch tube K1 and the switch tube K2 are both NMOS tubes, and the control drive circuit is an NMOS control drive circuit; The gates of the switch tube K1 and the switch tube K2 are respectively connected to the two output terminals of the control drive circuit; The drain of the switch tube K1 is connected to the positive electrode of the DC power supply DC, and the source of the switch tube K2 is connected to the negative electrode of the DC power supply DC, and serves as a connection node A; The source of the switch tube K1 is connected to the drain of the switch tube K2 and serves as a connection node B.

3. The high-frequency AC test equipment based on a switching tube according to claim 1 or 2, characterized in that: The output frequency of the control drive circuit is adjustable.

4. A high-frequency AC testing method based on a switching tube, using a high-frequency AC testing device based on a switching tube according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Connect the product under test to the high-frequency AC test equipment based on a switching tube according to the test requirements; Step 2: Determine the frequency f of the output of the control drive circuit according to the test requirements; Step 3: Determine the inductance value of the inductor L and / or the capacitance value of the capacitor C according to the test requirements; Step 4: Control the switch tubes K1 and K2 to alternately conduct at a frequency f and a duty cycle of 50% according to the corresponding control signal, generating a square wave signal with a frequency f, an amplitude U, and a duty cycle of 50%, thereby generating a high-frequency, sinusoidal resonant current in the resonant circuit; Step 5: Adjust the voltage of the DC power supply DC, thereby adjusting the amplitude U of the resonant current, so that the magnitude of the resonant current flowing through the DUT meets the test requirements. Measure the operating parameters of the DUT under the resonant current through the test device to complete the test.

5. The high-frequency AC testing method based on a switching tube according to claim 4, characterized in that: In step 3, the inductance of the inductor L and / or the capacitance of the capacitor C are calculated according to the test frequency f using the following formula: f=1 / 2π√(lc); Where: l and c are the inductance of the inductor L and the capacitance of the capacitor C, or the inductance of the inductor L and the capacitance of the measured product, or the inductance of the measured product and the capacitance of the capacitor C, respectively.

6. A high-frequency AC testing method based on a switching tube according to claim 4 or 5, characterized in that: Step 5 also includes: Continue to increase the voltage provided by the DC power supply and measure the working status of the DUT under the limit resonant current.

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