Resonant inversion module, control method, power supply device and alternating current test transmission instrument

Abstract

The invention discloses a resonant inversion module, a control method, a power supply device and an alternating current test transmission instrument, relates to the technical field of electronic information, and solves the problems that the frequency regulation and control algorithm of the inversion module is complicated, and harmonic distortion is easily caused by calculation errors. By utilizing the characteristic that the frequency of the steady-state current in the LC oscillating circuit is consistent with the resonant frequency, the loop current in the resonant inversion module is obtained, and the driving signal with the same phase is sent to the switching tube of the resonant inversion module based on the phase of the loop current, so that the output voltage frequency of the resonant inversion module can be consistent with the resonant frequency, and the output voltage frequency of the resonant inversion module is consistent with the resonant frequency. And the frequency locking effect is achieved. The resonant inversion module provided by the embodiment of the invention is simple in frequency regulation and control process and high in practicability, and the switching tube is driven by taking the current phase as the phase of the driving signal, so that the phases of the output voltage and the output current are consistent, and harmonic distortion is reduced.

Description

Technical Field

[0001] The present invention relates to the field of electronic information technology, and in particular to a resonant inverter module, a control method, a power supply device and an AC test transmitter. Background Art

[0002] Many electrical devices (such as transformers, generators, and frequency-sensitive equipment) perform differently at different frequencies. Therefore, many industries and standards require testing of electrical equipment at specific frequencies, particularly in the communications, industrial, and aerospace sectors. Overhead power lines must operate stably for extended periods of time, but load variations and system fluctuations in actual operation can cause fluctuations in grid frequency. A variable-frequency AC tester can help test the grid's ability to operate at different frequencies, ensuring system reliability and safety.

[0003] Variable-frequency AC test transmitters typically consist of a DC boost module and an inverter module. These modules boost and invert the DC voltage of a portable DC power supply to generate the AC voltage required for device testing. Currently, inverter modules on the market are primarily designed for long-term grid operation. To adapt to the complex operating conditions of the grid and ensure operational stability and accuracy despite various environmental factors, the inverter modules' circuit structures and frequency control algorithms are complex, making them susceptible to harmonic distortion due to calculation errors and resulting in high costs.

[0004] In view of this, a resonant inverter module, a control method, a power supply device and an AC test transmitter are needed. Summary of the Invention

[0005] To address the problem in existing technologies where the inverter module frequency control algorithm is complex and easily leads to harmonic distortion due to calculation errors, the present invention provides a resonant inverter module, control method, power supply device, and AC test transmitter. The frequency control process is simple, practical, and can reduce harmonic distortion. The specific technical solution is as follows:

[0006] In a first aspect, an embodiment of the present application provides a resonant inverter module, which includes a controller, a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first measuring capacitor C1, a second measuring capacitor C2, an adjustable capacitor C3, a loop resistor R1, and a loop inductor L;

[0007] The first end of the first switch tube Q1 is connected to the positive electrode of the DC voltage input terminal, the second end of the second switch tube Q2 is connected to the negative electrode of the DC voltage input terminal, and the second end of the first switch tube Q1 is connected to the first end of the second switch tube Q2; the first end of the third switch tube Q3 is connected to the first end of the first switch tube, the second end of the fourth switch tube Q4 is connected to the second end of the second switch tube, and the second end of the third switch tube Q3 is connected to the first end of the fourth switch tube Q4; the first switch tube Q1 is connected in parallel with the first diode D1, the second switch tube Q2 is connected in parallel with the second diode D2, the third switch tube Q3 is connected in parallel with the third diode D3, and the fourth switch tube Q4 is connected in parallel with the fourth diode D4.

[0008] The midpoint of the upper arm of the inverter bridge formed by the first switching tube Q1 and the second switching tube Q2 is connected to the first end of the loop resistor R1, the second end of the loop resistor R1 is connected to the first end of the loop inductor L, the second end of the loop inductor L is connected to the first end of the first measuring capacitor C1 and the first end of the adjustable capacitor C3, respectively, the second end of the first measuring capacitor C1 is connected to the first end of the second measuring capacitor C2, the second end of the second measuring capacitor C2 and the second end of the adjustable capacitor C3 are both connected to the midpoint of the lower arm of the inverter bridge; the lower arm of the inverter bridge is formed by the third switching tube Q3 and the fourth switching tube Q4; the two ends of the adjustable capacitor C3 are connected to the output end of the resonant inverter module;

[0009] The first end of the controller is connected to the second end of the second measuring capacitor, and the second end of the controller is respectively connected to the third end of the first switch tube Q1, the third end of the second switch tube Q2, the third end of the third switch tube Q3, and the third end of the fourth switch tube Q4;

[0010] The controller is used to obtain the loop current I1 and send a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 based on the phase of the loop current I1.

[0011] Preferably, it is characterized in that the controller includes a current sampling unit, a zero-crossing detection unit, a frequency locking unit and a pulse width modulation (PWM) unit; the current sampling unit is used to collect the loop current I1; the zero-crossing detection unit is used to detect the zero-crossing point of the loop current I1; the frequency locking unit is used to send a phase offset corresponding to the phase of the loop current I1 corresponding to the zero-crossing point to the PWM unit based on the phase of the loop current I1; the PWM unit is used to send a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 based on the phase offset.

[0012] In a second aspect, an embodiment of the present application provides a control method for a resonant inverter module, which is applied to a controller in the resonant inverter module as described in the first aspect; the method includes:

[0013] The controller obtains the loop current I1 and sends a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 and the fourth switch tube Q4 based on the phase of the loop current I1 .

[0014] Preferably, the controller includes a current sampling unit, a zero-crossing detection unit, a frequency locking unit, and a pulse width modulation (PWM) unit; the drive signal includes a PWM wave; the controller obtains the loop current I1, and based on the phase of the loop current I1, sends a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4, including:

[0015] The current sampling unit is used to collect the loop current I1; the zero-crossing detection unit is used to detect the zero-crossing point of the loop current I1; the frequency locking unit is used to send the phase offset corresponding to the phase to the PWM unit based on the phase of the loop current I1 corresponding to the zero-crossing point; the PWM unit sends the drive signal of the same phase or the drive signal of the complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 based on the phase offset.

[0016] Preferably, before the controller obtains the loop current I1 and sends a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 based on the phase of the loop current I1, the method also includes: obtaining the capacitance value of the circuit to be tested or the capacitance value of the device to be tested, and the target frequency of the working condition to be tested; based on one of the capacitance value of the circuit to be tested and the capacitance value of the device to be tested, and the target frequency, calculating the target inductance value of the loop inductance L and the target capacitance value of the adjustable capacitor C3 in the resonant inverter module; setting the loop inductance L based on the target inductance value, and adjusting the adjustable capacitor C3 based on the target capacitance value.

[0017] In a third aspect, an embodiment of the present application provides a power supply device, which includes any possible resonant inverter module described in the first aspect, and a DC-DC module, wherein the output end of the DC-DC module is connected to the input end of the resonant inverter module; the DC-DC module is used to increase the power supply voltage and input it into the resonant inverter module.

[0018] In a third aspect, an embodiment of the present application provides an AC test transmitter, which includes the power supply device described in the third aspect.

[0019] Compared with the prior art, the present invention has the following beneficial effects: utilizing the characteristic that the current frequency of the steady-state current in the LC oscillation circuit is consistent with the resonant frequency, obtaining the loop current I1 and sending a drive signal of the same phase to the switch tube of the resonant inverter module based on the phase of the loop current I1, so that the output voltage frequency of the resonant inverter module can be consistent with the resonant frequency, achieving the effect of frequency locking. The frequency control process of the resonant inverter module provided by the embodiment of the application is simple and practical, and the phase of the switch tube driven by the current phase as the drive signal is consistent with the output voltage and output current, thereby reducing harmonic distortion. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0021] Figure 1 A circuit structure diagram of a resonant inverter module provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of the structure of a controller provided in an embodiment of the present application;

[0023] Figure 3 A schematic flow chart of a resonant inverter module control method provided in an embodiment of the present application;

[0024] Figure 4 This is an overall structural diagram of an AC test transmitter provided in an embodiment of the present application;

[0025] Figure 5 This is a steady-state simulation diagram of a 50 Hz frequency test transmission to a 30 km overhead line provided in an embodiment of the present application;

[0026] Figure 6 A frequency adaptive locking simulation diagram provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0029] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0030] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0031] To address the problem in traditional solutions where the frequency control algorithm of the inverter module is complex and easily leads to harmonic distortion due to calculation errors, the present invention provides a resonant inverter module, a control method, a power supply device, and an AC test transmitter. The frequency control process is simple, practical, and can reduce harmonic distortion.

[0032] See also Figure 1 , Figure 1 This is a circuit diagram of a resonant inverter module provided in an embodiment of the present application. Figure 1 As shown, the resonant inverter module includes a controller, a first switch tube Q1, a second switch tube Q2, a third switch tube Q3, a fourth switch tube Q4, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first measuring capacitor C1, a second measuring capacitor C2, an adjustable capacitor C3, a loop resistor R1 and a loop inductor L.

[0033] The first end of the first switch tube Q1 is connected to the positive electrode of the DC voltage input terminal, the second end of the second switch tube Q2 is connected to the negative electrode of the DC voltage input terminal, and the second end of the first switch tube Q1 is connected to the first end of the second switch tube Q2; the first end of the third switch tube Q3 is connected to the first end of the first switch tube, the second end of the fourth switch tube Q4 is connected to the second end of the second switch tube, and the second end of the third switch tube Q3 is connected to the first end of the fourth switch tube Q4; the first switch tube Q1 is connected in parallel with the first diode D1, the second switch tube Q2 is connected in parallel with the second diode D2, the third switch tube Q3 is connected in parallel with the third diode D3, and the fourth switch tube Q4 is connected in parallel with the fourth diode D4.

[0034] The midpoint of the upper arm of the inverter bridge formed by the first switching tube Q1 and the second switching tube Q2 is connected to the first end of the loop resistor R1, the second end of the loop resistor R1 is connected to the first end of the loop inductor L, the second end of the loop inductor L is respectively connected to the first end of the first measuring capacitor C1 and the first end of the adjustable capacitor C3, the second end of the first measuring capacitor C1 is connected to the first end of the second measuring capacitor C2, and the second end of the second measuring capacitor C2 and the second end of the adjustable capacitor C3 are both connected to the midpoint of the lower arm of the inverter bridge; the lower arm of the inverter bridge is formed by the third switching tube Q3 and the fourth switching tube Q4; and the two ends of the adjustable capacitor C3 are connected to the output end of the resonant inverter module.

[0035] The first terminal of the controller is connected to the second terminal of the second measuring capacitor, and the second terminal of the controller is connected to the third terminal of the first switching tube Q1, the third terminal of the second switching tube Q2, the third terminal of the third switching tube Q3, and the third terminal of the fourth switching tube Q4. Specifically, the third terminal of the switching tube is the control electrode of the switching tube.

[0036] The controller is used to obtain the loop current I1 and, based on the phase of the loop current I1, send a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4.

[0037] Specifically, the first switching transistor Q1 and the fourth switching transistor Q4 form a group, and the second switching transistor Q2 and the third switching transistor Q3 form another group. The controller can send a drive signal of the same phase to one group while simultaneously sending a drive signal of a complementary phase to the other group, turning one group on and the other off, thereby outputting the load voltage. By controlling the switching timing with high-frequency PWM and adjusting the on-time ratio between the positive and negative half-cycles of the operating cycle, the average output voltage can be made to approach a sine wave.

[0038] Exemplarily, the controller may be a microcontroller unit (MCU).

[0039] See also Figure 2 , Figure 2 This is a schematic diagram of the structure of a controller provided in an embodiment of the present application. Figure 2 As shown, the controller includes a current sampling unit, a zero-crossing detection unit, a frequency locking unit and a pulse width modulation (PWM) unit.

[0040] Exemplarily, the current sampling unit is a CU8965 current sensor, and the controller converts the current analog signal into a digital signal through ADC sampling.

[0041] The current sampling unit is used to collect the loop current I1; the zero-crossing detection unit is used to detect the zero-crossing point of the loop current I1; the frequency locking unit is used to send the phase offset corresponding to the phase of the loop current I1 corresponding to the zero-crossing point to the PWM unit based on the phase of the loop current I1; the PWM unit is used to send PWM waves to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 based on the phase offset.

[0042] Among them, by detecting the loop current I1, when the steady-state current waveform passes through the zero point, the zero-crossing detection unit will output a pulse signal (usually a jump from low level to high level or vice versa). This pulse signal can be used as a timing control signal to control the switching frequency of the switch tube to be consistent with the frequency of the output current, so that the output voltage and the output current are in phase. At this time, the resonant network reaches a resonant state, achieving the effect of frequency locking.

[0043] The frequency locking unit can also be used to calculate the period of the loop current I1 and send the period and the phase offset to the PWM unit, so that the PWM unit can output a driving signal with the same frequency and phase as the loop current I1.

[0044] Among them, Figure 2 In a specific example, the controller further includes a drive unit and a NOT gate unit. The drive unit is configured to amplify and enhance the signal output by the PWM unit to provide sufficient power and current to drive the switch. The NOT gate unit is configured to perform a logical inversion operation on the input signal, i.e., when the input is high, the output is low; and when the input is low, the output is high. In the embodiment of the present application, the NOT gate unit can obtain the complementary phase signal based on the same phase signal input by the PWM unit.

[0045] That is to say, the frequency locking unit only needs to calculate the phase offset of the loop current I1 at the zero-crossing point, and the PWM unit transmits a first PWM wave corresponding to the phase offset to the drive unit and the NOT gate unit; the NOT gate unit converts the first PWM wave into a complementary second PWM wave and sends the second PWM wave to the drive unit; the drive unit amplifies and enhances the two PWM waves and inputs them into the two groups of switch tubes respectively.

[0046] For example, after the resonant inverter module is connected to the power supply and the load, after 60-80ms, the loop current in the resonant inverter module enters a steady state. At this time, when the zero-crossing detection unit detects the zero-crossing point of the steady-state current, the PWM unit outputs a drive signal with the same frequency and phase as the current to the switch tube (for example, when the sinusoidal current changes from negative to positive, the PWM unit outputs a positive drive signal). If a positive drive signal is output to the Q1 and Q4 switch tubes, a complementary negative drive signal is output to the Q2 and Q3 switch tubes at the same time. At this time, the switching frequency is consistent with the natural frequency of the resonant network, so that the output voltage and the output current are in phase, and the resonant network reaches the optimal resonant state. When the adjustable capacitor C3 is adjusted, the natural frequency of the system changes, and repeating the above steps can eventually reach a new steady-state frequency value.

[0047] Due to the zero current characteristic of sending PWM waves to switch the switch tube state at the zero-crossing point, less electromagnetic noise and harmonics are generated. Compared with high-frequency switching of traditional PWM and other methods, the embodiment of the present application has better harmonic control characteristics in low-frequency applications.

[0048] The embodiment of the present application has a fast response speed (less than one transmission signal cycle) during zero-crossing detection and high locking frequency accuracy (the error is determined only by the circuit detection delay, generally in the microsecond range). At the same time, frequency regulation is performed during sinusoidal zero-crossing switching, and electromagnetic interference is low.

[0049] Preferably, the output voltage range of the resonant inverter module is 20-300 Hz.

[0050] Exemplarily, the capacitances of the first measuring capacitor C1 and the second measuring capacitor C2 are 10 nF and 2.2 nF respectively; and the inductance of the loop inductor L is 1 H.

[0051] Exemplarily, the rated operating frequency of the first switching tube Q1 , the second switching tube Q2 , the third switching tube Q3 and the fourth switching tube Q4 is 50 Hz.

[0052] The embodiments of the present application utilize the characteristic that the current frequency of the steady-state current in the LC oscillator circuit is consistent with the resonant frequency, obtain the loop current I1, and send a drive signal of the same phase to the switch tube of the resonant inverter module based on the phase of the loop current I1, so that the output voltage frequency of the resonant inverter module can be consistent with the resonant frequency, achieving a frequency locking effect. The frequency control process of the resonant inverter module provided by the embodiments of the present application is simple and practical, and the phase of the switch tube driven by the current phase as the drive signal is consistent with the output voltage and output current, thereby reducing harmonic distortion.

[0053] The structure of the resonant inverter module provided in the embodiment of the present application is described above, and the control method of the resonant inverter module will be described below.

[0054] See also Figure 3 , Figure 3 A schematic flow chart of a resonant inverter module is provided for an embodiment of the present application. The method is applied to a controller in the resonant inverter module as described in the first aspect; Figure 3 As shown, the method includes:

[0055] Step 301: The controller obtains the loop current I1 and sends a drive signal of the same phase or a drive signal of a complementary phase to the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 based on the phase of the loop current I1.

[0056] Preferably, the controller includes a current sampling unit, a zero-crossing detection unit, a frequency locking unit and a pulse width modulation (PWM) unit; the current sampling unit collects the loop current I1; the zero-crossing detection unit detects the zero-crossing point of the loop current I1; the frequency locking unit sends the duty cycle corresponding to the same phase and the duty cycle corresponding to the complementary phase to the PWM unit based on the phase of the loop current I1 corresponding to the zero-crossing point; the PWM unit sends the PWM wave corresponding to the duty cycle of the same phase, or the PWM wave corresponding to the duty cycle of the complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4.

[0057] The content of the above method can be understood by referring to the content of the structure part, and will not be repeated here.

[0058] A tester is primarily used to determine whether a power line is safe to resume power transmission after a fault has occurred and tripped. It simulates the power transmission process to verify whether the fault has been eliminated and whether the line's insulation and other properties have recovered to a level capable of withstanding normal operating voltages. The tester typically applies a low test voltage (lower than the normal operating voltage) to the line, which can, to a certain extent, verify the insulation performance of the line. It also monitors changes in parameters such as current. If no abnormalities, such as excessive short-circuit current, occur during the application of the test voltage, it can be preliminarily determined that the line is likely capable of normal power transmission. Conversely, if an abnormally high current is detected, this indicates potential faults, such as insulation failure or grounding issues, which require further inspection and resolution.

[0059] When the resonant inverter module provided in the embodiment of the present application is applied to the scenario of an AC test transmitter, it is necessary to first determine the target frequency according to the needs of the test scenario, and then adjust the overall resonant frequency of the resonant inverter module after connecting it to the circuit to be tested or the device to be tested to be consistent with the target frequency. This can reduce energy loss, improve power factor, and also improve the accuracy of the test.

[0060] Preferably, before the controller obtains the loop current I1 and sends a drive signal of the same phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 based on the phase of the loop current I1, the method also includes: obtaining the capacitance value of the circuit to be tested or the capacitance value of the device to be tested, and the target frequency of the working condition to be tested; then, based on one of the capacitance value of the circuit to be tested and the capacitance value of the device to be tested, and the target frequency, calculating the target inductance value of the loop inductance L and the target capacitance value of the adjustable capacitor C3 in the resonant inverter module; then, setting the loop inductance L based on the target inductance value, and adjusting the adjustable capacitor C3 based on the target capacitance value.

[0061] It is understandable that the actions of setting the loop inductance L and adjusting the adjustable capacitor C3 can be performed manually or by a machine.

[0062] Preferably, for the scenario of the line to be tested, since the overhead line within 50 km is capacitive, the entire overhead line can be equivalent to a capacitor; please refer to Figure 4 After the AC tester is connected to the overhead line, the equivalent capacitor C5 is connected in parallel with the adjustable capacitor C3. At this time, the first measuring capacitor C1, the second measuring capacitor C2, the adjustable capacitor C3 and the line equivalent capacitor C5 can be regarded as an equivalent capacitor C11.

[0063] The equivalent capacitance C11 satisfies: At this time, the resonant frequency calculation formula corresponding to the system composed of the resonant inverter module and the circuit to be tested can be It is understandable that the capacitances of the first measuring capacitor C1 and the second measuring capacitor C2 are smaller than those of the adjustable capacitor C3 and the circuit equivalent capacitor C5 , and thus can be ignored in the calculation.

[0064] When the target frequency is known, the range of the loop inductance L can be roughly calculated using the above formula, and then the system's natural resonant frequency can be changed by fine-tuning the adjustable capacitor C3, which is equivalent to changing the output frequency.

[0065] The present invention also provides a power supply device, which includes: Figure 1 The resonant inverter module and the DC-DC module, the output end of the DC-DC module is connected to the input end of the resonant inverter module; the DC-DC module is used to increase the power supply voltage and input it into the resonant inverter module.

[0066] The present application also provides an AC test transmitter, which is not only convenient but also supports a wide range of voltages and frequencies, and can be used in various types of power systems to meet the needs of different regions and systems. Specifically, the AC test transmitter provided in the present application includes the above-mentioned power supply device.

[0067] See also Figure 4 , Figure 4 This is an overall structural diagram of an AC test transmitter provided in an embodiment of the present application, such as Figure 4 As shown, the AC test transmitter includes a high-gain DC-DC module and an inverter resonance module; the output end of the high-gain DC-DC module is connected to the input end of the inverter resonance module, and the output end of the inverter resonance module is connected to the transmission line.

[0068] Among them, the structure of the resonant inverter module is the same as the above Figure 1 The structure of the embodiment shown is similar, and the structure of the controller in the resonant inverter module is the same as that of the above embodiment. Figure 2 The structures in the illustrated embodiments are similar and will not be described again here.

[0069] The output end of the DC-DC module is connected to the two ends of the upper bridge arm of the inverter bridge in the inverter resonant module, the second end of the loop inductor L is connected to the first end of the line inductor Lline, the second end of the line inductor Lline is connected to the line capacitor C4 and the first end of the line resistor Rline respectively, the second end of the line resistor Rline is connected to the first end of the line ground resistance R; the second end of the line ground resistance R is connected to the midpoint of the lower bridge arm of the inverter, and a complete loop is formed through the lower bridge arm.

[0070] For example, when a 48V DC voltage source outputs a 400V DC voltage through a high-gain DC-DC module, it is then converted from DC to AC into 6.4kV AC power through a resonant inverter module for line testing.

[0071] For example, the line resistance of a 30 km overhead line loop is 10.06 Ω.

[0072] See also Figure 5 and Figure 6 ,Depend on Figure 5 It can be seen that when the overhead line is 30 km long, the output can achieve 50HZ accurate frequency locking within 0.1S; Figure 6 It can be seen that when the frequency is locked, the output voltage of the resonant inverter module and the loop current (ie, the output current of the resonant inverter module) are in phase with each other, and the system reaches a resonant state.

[0073] Because overhead lines vary in length, their ground capacitance parameters also vary accordingly. When connected to an overhead line, the present invention can adjust the operating frequency required for overhead line testing by varying the loop inductance L and adjustable capacitor C3 to match the overhead line. Furthermore, the zero-crossing detection module collects the sinusoidal current in the loop, enabling the controller to quickly lock onto the desired operating frequency and drive the switch to output the required voltage pulses with the same frequency and phase as the sinusoidal current.

[0074] Those skilled in the art will appreciate that the units of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition of each example has been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0075] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0076] In the several embodiments provided in the embodiments of the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0077] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of the solution of this embodiment according to actual needs.

[0078] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0079] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM), random access memory (RAM), mobile hard disk, magnetic disk or optical disk, and other media that can store program codes.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A resonant inverter module, characterized in that: It includes a controller, a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first measuring capacitor C1, a second measuring capacitor C2, an adjustable capacitor C3, a loop resistor R1 and a loop inductor L; A first end of the first switch transistor Q1 is connected to the positive electrode of the DC voltage input terminal, a second end of the second switch transistor Q2 is connected to the negative electrode of the DC voltage input terminal, and a second end of the first switch transistor Q1 is connected to the first end of the second switch transistor Q2; a first end of the third switch transistor Q3 is connected to the first end of the first switch transistor, a second end of the fourth switch transistor Q4 is connected to the second end of the second switch transistor, and a second end of the third switch transistor Q3 is connected to the first end of the fourth switch transistor Q4; the first switch transistor Q1 is connected in parallel to the first diode D1, the second switch transistor Q2 is connected in parallel to the second diode D2, the third switch transistor Q3 is connected in parallel to the third diode D3, and the fourth switch transistor Q4 is connected in parallel to the fourth diode D4; The midpoint of the upper arm of the inverter bridge formed by the first switching tube Q1 and the second switching tube Q2 is connected to the first end of the loop resistor R1, the second end of the loop resistor R1 is connected to the first end of the loop inductor L, the second end of the loop inductor L is connected to the first end of the first measuring capacitor C1 and the first end of the adjustable capacitor C3, respectively, the second end of the first measuring capacitor C1 is connected to the first end of the second measuring capacitor C2, and the second end of the second measuring capacitor C2 and the second end of the adjustable capacitor C3 are both connected to the midpoint of the lower arm of the inverter bridge; the lower arm of the inverter bridge is formed by the third switching tube Q3 and the fourth switching tube Q4; the two ends of the adjustable capacitor C3 are connected to the output end of the resonant inverter module; The first end of the controller is connected to the second end of the second measuring capacitor, and the second end of the controller is respectively connected to the third end of the first switch tube Q1, the third end of the second switch tube Q2, the third end of the third switch tube Q3, and the third end of the fourth switch tube Q4; The controller is used to obtain the loop current I1 and send a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 based on the phase of the loop current I1.

2. The resonant inverter module according to claim 1, characterized in that: The controller includes a current sampling unit, a zero-crossing detection unit, a frequency locking unit and a pulse width modulation (PWM) unit; The current sampling unit is used to collect the loop current I1; The zero-crossing detection unit is used to detect the zero-crossing point of the loop current I1; The frequency locking unit is configured to send a phase offset value corresponding to the phase of the loop current I1 corresponding to the zero-crossing point to the PWM unit; The PWM unit is configured to send the drive signal of the same phase or the drive signal of the complementary phase to the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 , and the fourth switch tube Q4 based on the phase offset value.

3. A control method for a resonant inverter module, characterized in that: The method is applied to the controller in the resonant inverter module according to claim 1 or 2; the method comprises: The controller obtains the loop current I1 and sends a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 and the fourth switch tube Q4 based on the phase of the loop current I1 .

4. The method according to claim 3, characterized in that The controller includes a current sampling unit, a zero-crossing detection unit, a frequency locking unit, and a pulse width modulation (PWM) unit; the drive signal includes a PWM wave; the controller obtains the loop current I1 and, based on the phase of the loop current I1, sends a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4, including: The current sampling unit collects the loop current I1; The zero-crossing detection unit detects the zero-crossing point of the loop current I1; The frequency locking unit sends a phase offset corresponding to the phase to the PWM unit based on the phase of the loop current I1 corresponding to the zero-crossing point; The PWM unit sends the driving signal of the same phase or the driving signal of the complementary phase to the first switching transistor Q1 , the second switching transistor Q2 , the third switching transistor Q3 , and the fourth switching transistor Q4 based on the phase offset.

5. The method according to claim 3 or 4, characterized in that Before the controller obtains the loop current I1 and sends a drive signal of the same phase or a drive signal of a complementary phase to the first switch tube Q1, the second switch tube Q2, the third switch tube Q3, and the fourth switch tube Q4 based on the phase of the loop current I1, the method further includes: Obtaining the capacitance value of the circuit to be tested or the capacitance value of the device to be tested, as well as the target frequency of the working condition to be tested; Calculating a target inductance value of the loop inductor L and a target capacitance value of the adjustable capacitor C3 in the resonant inverter module based on one of the capacitance value of the circuit to be tested and the capacitance value of the device to be tested, as well as the target frequency; The loop inductance L is set based on the target inductance value, and the adjustable capacitor C3 is adjusted based on the target capacitance value.

6. A power supply device, characterized in that: The power supply device includes the resonant inverter module according to claim 1 or 2, and a DC-DC module, wherein the output end of the DC-DC module is connected to the input end of the resonant inverter module; the DC-DC module is used to increase the power supply voltage and input it into the resonant inverter module.

7. An AC test transmitter, characterized in that: The AC test transmitter includes the power supply device according to claim 6.

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