Test platform and test method for LCC-SS-T topology based on impedance characteristic identification

Abstract

This invention discloses a test platform and method for LCC-SS-T topologies based on impedance characteristic identification, which offers high testing efficiency, avoids parameter interference, and provides accurate judgment. The test platform for LCC-SS-T topologies based on impedance characteristic identification includes: an LCC-SS-T topology formed by a primary-side resonant component under test (DUT) and a secondary-side DUT; a primary-side inverter: used to output a drive waveform with a frequency of 40kHz-200kHz to drive the LCC-SS-T topology to complete the test process; a PFC module: used to connect to the power grid for power factor correction and to convert AC power from the grid into DC power input to the primary-side inverter; a secondary-side test load module: used to receive energy transmitted from the primary side of the test platform; and test equipment: used to receive and calculate the midpoint voltage and resonant current of the primary-side DUT and the midpoint voltage and resonant current of the secondary-side DUT, and further calculate the impedance. This invention is applied in the field of wireless charging technology.

Description

Technical Field

[0001] This invention relates to a test platform and test method for LCC-SS-T topology based on impedance characteristic identification, and particularly to a parameter test platform and test method for wireless charging system for LCC-SS-T topology based on impedance characteristic identification. Background Technology

[0002] Wireless charging systems, based on the principles of electromagnetic induction coupling or magnetic resonance, achieve efficient energy transfer through contactless energy transmission. They are used in electric vehicles, consumer electronics, and industrial automation.

[0003] LCC-SS-T is a common topology in wireless charging systems. It is a topology designed to make good use of the constant voltage output characteristics of LCC-SS and to further improve the output current level.

[0004] like Figure 1 As shown, in the LCC-SS-T topology, the transmitter topology is LCC, SS refers to the receiver being a series resonant structure, and T is an additional high-frequency transformer structure integrated at the receiver to further increase the output current.

[0005] Although composite resonant topologies significantly improve the robustness of wireless charging systems to parameter drift, a key bottleneck still exists in their mass production: when the factory-shipped resonant parameters exceed the design tolerance range, it will cause a decline in the system's complex performance, ultimately resulting in batch-specific quality defects.

[0006] However, this composite resonant topology contains multiple resonant parameters that can influence each other and affect the individual parameter test results. Even after the resonant cavity assembly is installed, it is impossible to test these resonant parameters individually because testing methods such as Wheatstone bridges are affected by interference from other components within the resonant cavity assembly.

[0007] To ensure the batch testing and verification of wireless charging systems before they leave the factory, independent parameter testing of their resonant cavity components (including the transmitter coil and compensation network, and the receiver coil and resonant compensation structure) is required. However, current testing methods have the following drawbacks: 1. Low testing efficiency: The resonant cavity assembly contains multiple components, requiring the individual removal, calibration, and matching of complex resonant inductors and capacitors. Traditional methods necessitate testing at each frequency point, resulting in an excessively time-consuming testing process that cannot match the pace of the production line.

[0008] 2. Parameter Interference: Deviations in parameters such as coil inductance, resonant inductance, and series / parallel capacitance can have cumulative effects. During online measurement, the physical connection between the compensation network and the power device introduces parasitic impedance, causing the measured impedance to deviate from the true resonant cavity characteristics. Interference from other components within the resonant cavity assembly makes it impossible to accurately locate the problematic component.

[0009] 3. Inaccurate judgment: Using current experience to judge whether parameters are qualified can easily lead to misjudgment (judging potentially defective parts as qualified).

[0010] Therefore, achieving a rapid and accurate testing process remains a critical technical bottleneck that urgently needs to be overcome. Thus, developing a parameter testing platform and method for wireless charging systems with LCC-SS-T topology based on impedance characteristic identification, capable of quickly determining whether factory parameters meet standards using the characteristics of resonant impedance, has become a key requirement for improving the mass production quality of wireless charging systems. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a test platform and test method for LCC-SS-T topology based on impedance characteristic identification, which has high test efficiency, avoids mutual interference of parameters and has accurate judgment.

[0012] The technical solution adopted in this invention is as follows: This invention includes a test platform and test method for LCC-SS-T topology based on impedance characteristic identification; the test platform for LCC-SS-T topology based on impedance characteristic identification includes: Primary-side resonant component under test: including LCC transmitter topology; Secondary-side resonant components under test: including the SS receiver series resonant structure and the high-frequency transformer structure; The primary-side resonant component under test and the secondary-side resonant component under test form an LCC-SS-T topology; the test platform also includes: Primary-side inverter: It is a full-bridge converter, and the input terminal of the primary-side resonant component under test is connected to the output port of the full-bridge converter. It operates through phase-shifted full-bridge modulation to achieve a drive waveform with an output frequency of 40k-200kHz, which is used to drive the LCC-SS-T topology to complete the test process. PFC module: Used to connect to the power grid for power factor correction and to convert the AC power from the grid into DC power for input to the primary side inverter; Secondary-side test load module: The output terminal of the secondary-side resonant component under test is connected to the input port of the secondary-side test load module to receive energy transmitted from the primary side by the test platform; Test equipment includes two voltage probes, two current probes, and a processing device. The two voltage probes are used to test the midpoint voltage of the primary-side resonant component under test and the midpoint voltage of the secondary-side resonant component under test, respectively. The two current probes are used to test the resonant current of the primary-side resonant component under test and the resonant current of the secondary-side resonant component under test, respectively. The processing device is used to receive, process, and calculate the phase difference between the midpoint voltage of the primary-side resonant component under test, the midpoint voltage of the secondary-side resonant component under test, the resonant current of the primary-side resonant component under test, and the resonant current of the secondary-side resonant component under test, and further calculate the magnitude of the impedance.

[0013] Furthermore, both voltage probes are high-voltage differential probes, both current probes are high-frequency AC probes, the processing device is a computer, and both the voltage probes and the current probes receive data through the acquisition card of the test equipment, convert the continuous analog signal into discrete data points, and then transmit the processed digital signal to the computer through its data transmission interface.

[0014] Furthermore, the PFC module is a single-phase Vienna topology.

[0015] Furthermore, the secondary-side test load module is a rectifier bridge module.

[0016] Furthermore, a test method for LCC-SS-T topology based on impedance characteristic identification includes the following steps: S1. Connect the input terminal of the primary side resonant component under test to the output port of the full-bridge converter; S2. Connect the output terminal of the secondary-side resonant cavity assembly under test to the input port of the secondary-side test load module; S3. Connect two voltage probes to the primary side resonant component under test and the secondary side resonant component under test respectively. The two voltage probes are used to measure the midpoint voltage of the primary side resonant component under test and the midpoint voltage of the secondary side resonant component under test respectively. Connect two current probes to the primary side resonant component under test and the secondary side resonant component under test respectively. The two current probes are used to measure the resonant current of the primary side resonant component under test and the resonant current of the secondary side resonant component under test respectively. S4. Connect both voltage probes and both current probes to the data acquisition card, and then connect it to the computer; S5. Turn on the grid power switch, and then turn on the PFC module and the primary inverter in sequence; S6. The primary inverter performs a frequency sweep operation, outputting a drive waveform from 40kHz to 200kHz. S7. The test equipment records the magnitude and phase of each key waveform during the frequency sweep and establishes an impedance model diagram; S8. Compare the impedance model diagram established during the frequency sweep with the standard impedance model diagram to determine the qualification status of the resonant components of the LCC-SS-T topology; S9. Turn off the primary inverter and PFC module, and finally turn off the grid power switch.

[0017] Furthermore, during the frequency sweep, the impedance model diagrams established include the input impedance spectrum of the LCC-SS-T topology within a certain frequency range, the output impedance spectrum of the LCC-SS-T topology within a certain frequency range, the equivalent impedance spectrum from the secondary side to the primary side of the LCC-SS-T topology within a certain frequency range, and the equivalent impedance spectrum from the primary side to the secondary side of the LCC-SS-T compensation topology within a certain frequency range.

[0018] Furthermore, the method for calculating the input impedance value using the resonant current of the primary-side resonant component under test and the magnitude and phase of the midpoint voltage of the primary-side resonant component under test is as follows: , Z p_in V is the input impedance. pi i is the midpoint voltage of the primary-side resonant component under test. lrp φ is the resonant current of the primary-side resonant component under test. p The phase shift angle of the full-bridge resonant component under test on the primary side is given by ω, where j is the imaginary unit and ω is the angular frequency. The method for calculating the output impedance value using the resonant current of the secondary-side resonant component under test and the magnitude and phase of the midpoint voltage of the secondary-side resonant component under test is as follows: ,

[0019] Z s_in V is the output impedance. si i is the midpoint voltage of the secondary-side resonant component under test. Ts φ is the resonant current of the secondary side resonant component under test. s θ is the full-bridge phase shift angle of the secondary-side resonant component under test. c It is the system phase difference, θ t It is the phase difference of the high-frequency transformer; The equivalent impedance from the secondary side to the primary side of the LCC-SS-T topology is calculated as follows: ,

[0020] Z s_p Z is the equivalent impedance from the secondary side to the primary side, where Z s_p Z is the equivalent impedance from the secondary side to the primary side, where Z s_p This represents the equivalent impedance from the secondary side to the primary side, where the impedance used from the secondary side to the primary side is as follows: Z pi The ground-terminal resonant inductor branch impedance is the equivalent impedance of the resonant inductor branch viewed from the secondary side towards the ground. Z pr The impedance of the parallel capacitor branch at the ground terminal is the equivalent impedance of the parallel capacitor branch and other impedance components viewed from the secondary side to the ground terminal. Z prt The ground-end resonant coil branch impedance is the equivalent impedance of the resonant coil branch and other impedance components viewed from the secondary side towards the ground. Z prs The ground-to-vehicle resonant branch impedance is the equivalent impedance of the vehicle-end coil branch and other impedance components viewed from the secondary side to the ground. Z prst Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z prc Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z s_in :The input impedance at the vehicle end, the input impedance viewed from the secondary side towards the entire resonant cavity; The equivalent impedance from the primary side to the secondary side of the LCC-SS-T compensated topology is calculated as follows: , Z p_s This is the equivalent impedance from the primary side to the secondary side. The impedances used from the primary side to the secondary side include the following: Z si Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z sr Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z srt The impedance of the resonant coil branch at the vehicle end is the equivalent impedance of the resonant coil branch and other impedance components viewed from the primary side towards the vehicle end. Z srp The impedance of the resonant branch from the vehicle end to the ground end is the equivalent impedance of the ground coil branch and other impedance components viewed from the primary side towards the vehicle end. Z srpt The impedance of the resonant transmitter branch from the vehicle end to the ground end is the equivalent impedance of the branch containing the leakage inductance and series capacitance of the ground coil and transmitter coil, as well as other impedance components, when viewed from the primary side towards the vehicle end. Zsrc The impedance of the parallel capacitor branch from the vehicle end to the ground end is the equivalent impedance of the parallel capacitor branch at the ground end as viewed from the primary side towards the vehicle end, along with other impedance components in front of it. Z p_in : Ground input impedance, the input impedance viewed from the secondary side towards the entire resonant cavity.

[0021] The beneficial effects of this invention are: 1. High testing efficiency: Unlike traditional methods that require complex parameter testing at each frequency point, this invention allows for rapid acquisition of impedance spectra through continuous frequency sweeping, resulting in a shorter testing process and significantly improved testing efficiency on the production line; 2. Avoidance of parameter interference: This invention eliminates the need to test the parameters of each resonant component individually. Instead, it identifies the resonant performance based on the overall characteristic impedance, thus avoiding mutual interference between resonant parameters; 3. Accurate judgment: The invention uses characteristic impedance spectra to determine parameter compliance, making the operation simple and quick. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the LCC-SS-T topology; Figure 2 This is a schematic diagram of the testing platform; Figure 3 This is a schematic diagram of the key waveforms of the LCC-SS-T system; Figure 4 This is a schematic diagram of four key waveforms actually measured in the embodiment; Figure 5 This is a schematic diagram showing the relationship between input impedance and operating frequency; Figure 6 This is a schematic diagram showing the relationship between output impedance and operating frequency; Figure 7 This is a schematic diagram showing the relationship between the equivalent impedance from the secondary side to the primary side and the operating frequency. Figure 8 This is a schematic diagram showing the relationship between the equivalent impedance from the primary side to the secondary side and the operating frequency. Detailed Implementation

[0023] like Figure 1 and Figure 2 As shown, in this embodiment, the present invention includes a test platform and test method for LCC-SS-T topology based on impedance characteristic identification; the test platform for LCC-SS-T topology based on impedance characteristic identification includes: Primary-side resonant component under test: including LCC transmitter topology; Secondary-side resonant components under test: including the SS receiver series resonant structure and the high-frequency transformer structure; The primary-side resonant component under test and the secondary-side resonant component under test form an LCC-SS-T topology; the test platform also includes: Primary-side inverter: It is a full-bridge converter, and the input terminal of the primary-side resonant component under test is connected to the output port of the full-bridge converter. It operates through phase-shifted full-bridge modulation to achieve a drive waveform with an output frequency of 40k-200kHz, which is used to drive the LCC-SS-T topology to complete the test process. PFC module: Used to connect to the power grid for power factor correction and to convert the AC power from the grid into DC power for input to the primary side inverter; Secondary-side test load module: The output terminal of the secondary-side resonant component under test is connected to the input port of the secondary-side test load module to receive energy transmitted from the primary side by the test platform; Test equipment includes two voltage probes, two current probes, and a processing device. The two voltage probes are used to test the midpoint voltage of the primary-side resonant component under test and the midpoint voltage of the secondary-side resonant component under test, respectively. The two current probes are used to test the resonant current of the primary-side resonant component under test and the resonant current of the secondary-side resonant component under test, respectively. The processing device is used to receive, process, and calculate the phase difference between the midpoint voltage of the primary-side resonant component under test, the midpoint voltage of the secondary-side resonant component under test, the resonant current of the primary-side resonant component under test, and the resonant current of the secondary-side resonant component under test, and further calculate the magnitude of the impedance.

[0024] In this embodiment, both voltage probes are high-voltage differential probes, both current probes are high-frequency AC probes, the processing device is a computer, and both the voltage probes and the current probes receive data through the acquisition card of the test equipment, convert the continuous analog signal into discrete data points, and then transmit the processed digital signal to the computer through its data transmission interface.

[0025] In this embodiment, the PFC module is a single-phase Vienna topology.

[0026] In this embodiment, the secondary-side test load module is a rectifier bridge module.

[0027] In this embodiment, a test method for LCC-SS-T topology based on impedance characteristic identification includes the following steps: S1. Connect the input terminal of the primary side resonant component under test to the output port of the full-bridge converter; S2. Connect the output terminal of the secondary-side resonant cavity assembly under test to the input port of the secondary-side test load module; S3. Connect two voltage probes to the primary side resonant component under test and the secondary side resonant component under test respectively. The two voltage probes are used to measure the midpoint voltage of the primary side resonant component under test and the midpoint voltage of the secondary side resonant component under test respectively. Connect two current probes to the primary side resonant component under test and the secondary side resonant component under test respectively. The two current probes are used to measure the resonant current of the primary side resonant component under test and the resonant current of the secondary side resonant component under test respectively. S4. Connect both voltage probes and both current probes to the data acquisition card, and then connect it to the computer; S5. Turn on the grid power switch, and then turn on the PFC module and the primary inverter in sequence; S6. The primary inverter performs a frequency sweep operation, outputting a drive waveform from 40kHz to 200kHz. S7. The test equipment records the magnitude and phase of each key waveform during the frequency sweep and establishes an impedance model diagram. Each key waveform includes four key waveforms, namely... Figure 4 The ground terminal midpoint voltage V pi Ground resonant current I Lrp The voltage at the midpoint of the vehicle end, V si and transformer secondary terminal current I Ts ; S8. Compare the impedance model diagram established during the frequency sweep with the standard impedance model diagram to determine the qualification status of the resonant components of the LCC-SS-T topology; S9. Turn off the primary inverter and PFC module, and finally turn off the grid power switch.

[0028] In this embodiment, Figure 3 This is a schematic diagram of the key waveforms of the LCC-SS-T system. Figure 3 The key waveforms in and Figure 1 The positions shown correspond to several key waveforms, S p1 -S p4 yes Figure 2 The drive signal S in the primary inverter s1 -S s4 Yes, yes Figure 2 The drive signal under active rectification of the rectifier bridge of the secondary side test load in the test.

[0029] φ p and φ s These refer to the full-bridge phase shift angles on the primary and secondary sides, respectively. In this invention, these values ​​are fixed and maintained at a value close to π. (This is because the test process does not require strict control of the output power.) V pi It is the midpoint voltage of the primary side. Lrp It is the resonant current on the primary side.

[0030] V st It is the primary voltage of the transformer on the secondary side, i s This is the primary resonant current of the transformer on the secondary side. θ c It is the system phase difference.

[0031] V si It is the midpoint voltage of the secondary side. Ts This is the resonant current on the secondary side. θ t It is the phase difference of the high-frequency transformer.

[0032] In simple terms, this invention uses the values ​​and phase differences of various voltages and currents to calculate the complex values ​​of various impedances, and then compares the differences between traditional numerical analysis and standard impedance spectra to determine the qualification of the resonant cavity assembly.

[0033] In this embodiment, the impedance model diagram established during the frequency sweep includes the spectrum of the input impedance of the LCC-SS-T topology within a certain frequency range, the spectrum of the output impedance of the LCC-SS-T topology within a certain frequency range, the spectrum of the equivalent impedance from the secondary side to the primary side of the LCC-SS-T topology within a certain frequency range, and the spectrum of the equivalent impedance from the primary side to the secondary side of the LCC-SS-T compensation topology within a certain frequency range.

[0034] In this embodiment, the method for calculating the input impedance value using the resonant current of the primary-side resonant component under test and the magnitude and phase of the midpoint voltage of the primary-side resonant component under test is as follows: ,

[0035] Z p_in V is the input impedance. pi i is the midpoint voltage of the primary-side resonant component under test. lrp φ is the resonant current of the primary-side resonant component under test. p ω is the full-bridge phase shift angle of the primary-side resonant component under test, j is the imaginary unit. Simply put, j is the imaginary unit and it is not a variable, j²=-1; ω is the angular frequency, with the unit being radians per second. Its relationship with the frequency f is: ω=2πf; The method for calculating the output impedance value using the resonant current of the secondary-side resonant component under test and the magnitude and phase of the midpoint voltage of the secondary-side resonant component under test is as follows: ,

[0036] Z s_in V is the output impedance. si i is the midpoint voltage of the secondary-side resonant component under test. Ts φ is the resonant current of the secondary side resonant component under test. sθ is the full-bridge phase shift angle of the secondary-side resonant component under test. c It's the system phase difference, which is in Figure 3 As indicated, θ represents the phase difference between the ground midpoint voltage Vpi and the transformer primary voltage Vst at the vehicle end. This value is mainly determined by the resonant parameters of the LCC-SS, with the ideal value being 90° (no internal resistance and perfect resonance). Typically, it is a few degrees smaller, between 70° and 90°. t The phase difference in a high-frequency transformer refers to the phase difference of the voltage waveform between the transformer's output (primary) and input (secondary) terminals. Ideally, the voltage phase difference between the primary and secondary coils is 0 degrees or 180 degrees, depending on the winding direction and the polarity of the terminals with the same name.

[0037] The following is an analysis of the frequencies in the impedance spectrum, which is a derivation made solely for the sake of the patent's validity. In fact, if a standard impedance spectrum is available in advance (which can be obtained through prior testing of standard components), the implementation of this invention will not be affected even if the following analysis process is not understood.

[0038] like Figure 1 The calculation methods for each impedance component shown are shown in the table below:

[0039] Here, 'x' is replaced with 'p' or 's' to represent the quantity viewed from the secondary or primary perspective. For example, the quantity Zxrt is the same location, viewed from the primary perspective as Zsrt, and viewed from the secondary perspective as Zprt. Because LCC-SS is not a symmetrical structure, some quantities do not exist, and the corresponding positions in the table are marked 'none'.

[0040] The equivalent impedance from the secondary side to the primary side of the LCC-SS-T topology is calculated as follows: ,

[0041] Z s_p Z is the equivalent impedance from the secondary side to the primary side, where Z s_p This represents the equivalent impedance from the secondary side to the primary side, where the impedance used from the secondary side to the primary side is as follows: Z pi The ground-terminal resonant inductor branch impedance is the equivalent impedance of the resonant inductor branch viewed from the secondary side towards the ground. Z pr The impedance of the parallel capacitor branch at the ground terminal is the equivalent impedance of the parallel capacitor branch and other impedance components viewed from the secondary side to the ground terminal. Z prt The ground-end resonant coil branch impedance is the equivalent impedance of the resonant coil branch and other impedance components viewed from the secondary side towards the ground. Z prs The ground-to-vehicle resonant branch impedance is the equivalent impedance of the vehicle-end coil branch and other impedance components viewed from the secondary side to the ground. Z prst Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z prc Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z s_in :The input impedance at the vehicle end, the input impedance viewed from the secondary side towards the entire resonant cavity; The equivalent impedance from the primary side to the secondary side of the LCC-SS-T compensated topology is calculated as follows: , Z p_s Z is the equivalent impedance from the primary side to the secondary side. si Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z sr Since the LCC-SS is not a symmetrical structure, this component of impedance does not exist in this topology. It is marked as none in Table 1. Z srt The impedance of the resonant coil branch at the vehicle end is the equivalent impedance of the resonant coil branch and other impedance components viewed from the primary side towards the vehicle end. Z srp The impedance of the resonant branch from the vehicle end to the ground end is the equivalent impedance of the ground coil branch and other impedance components viewed from the primary side towards the vehicle end. Z srpt The impedance of the resonant transmitter branch from the vehicle end to the ground end is the equivalent impedance of the branch containing the leakage inductance and series capacitance of the ground coil and transmitter coil, as well as other impedance components, when viewed from the primary side towards the vehicle end. Z src The impedance of the parallel capacitor branch from the vehicle end to the ground end is the equivalent impedance of the parallel capacitor branch at the ground end as viewed from the primary side towards the vehicle end, along with other impedance components in front of it. Z p_in : Ground input impedance, the input impedance viewed from the secondary side towards the entire resonant cavity.

[0042] More specific implementation examples Figure 4As shown, the test equipment records the magnitude and phase of four key waveforms during the frequency sweep. The acquisition card records the magnitude and phase information of each waveform at each frequency point and sends it to the computer for recording and analysis. Through the calculation and analysis methods described above, the corresponding frequency spectrum is obtained. An example of this spectrum is shown below: like Figure 5 The input impedance Z of the LCC-SS-T topology is shown. p_in Various coupling coefficients k at characteristic frequency f w The impedance reaches its maximum value in the vicinity.

[0043] like Figure 6 The output impedance Z of the LCC-SS-T compensated topology is shown. s_in The maximum impedance for each different coupling coefficient k appears at different operating frequencies, producing a perplexing pattern of variation.

[0044] like Figure 7 It can be seen that, within a certain frequency range, the equivalent impedance Z from the secondary side to the primary side of the LCC-SS-T topology is... s_p At characteristic frequency f w It reaches its maximum value in the vicinity. Furthermore, as the coupling coefficient k increases, Z... s_p It will decrease monotonically.

[0045] like Figure 8 The equivalent impedance Z from the primary side to the secondary side of the LCC-SS-T topology is shown. p_s Clearly, if the system's resonance is good, Z p_s At characteristic frequency f w The value suddenly drops to zero in the vicinity. This characteristic is maintained within a certain range of variation of the coupling coefficient k.

[0046] Testers can quickly determine the qualification status of the resonant cavity component by observing the deviation of these four spectra within a certain coupling coefficient and frequency range.

[0047] This invention applies to the technical field of wireless charging in power electronics.

[0048] Although the embodiments of the present invention are described with reference to actual solutions, they do not constitute a limitation on the meaning of the present invention. Modifications to the embodiments and combinations with other solutions based on this specification will be obvious to those skilled in the art.

Claims

1. A test platform for LCC-SS-T topology based on impedance characteristic identification, comprising: Primary-side resonant device under test: including LCC transmitter topology Secondary-side resonant components under test: including the SS receiver series resonant structure and the high-frequency transformer structure. The primary-side resonant component under test and the secondary-side resonant component under test form an LCC-SS-T topology; characterized in that: the test platform further includes: Primary-side inverter: It is a full-bridge converter, and the input terminal of the primary-side resonant component under test is connected to the output port of the full-bridge converter. It operates by phase-shift full-bridge modulation and performs frequency sweep operation to achieve a drive waveform with an output frequency of 40k-200kHz, which is used to drive the LCC-SS-T topology to complete the test process. PFC module: Used to connect to the power grid for power factor correction and to convert the AC power from the grid into DC power for input to the primary side inverter; Secondary-side test load module: The output terminal of the secondary-side resonant component under test is connected to the input port of the secondary-side test load module to receive energy transmitted from the primary side by the test platform; Test equipment includes two voltage probes, two current probes, and a processing device. The two voltage probes are used to test the midpoint voltage of the primary-side resonant component under test and the midpoint voltage of the secondary-side resonant component under test, respectively. The two current probes are used to test the resonant current of the primary-side resonant component under test and the resonant current of the secondary-side resonant component under test, respectively. The processing device receives, processes, and calculates the phase difference between the midpoint voltage of the primary-side resonant component under test, the midpoint voltage of the secondary-side resonant component under test, the resonant current of the primary-side resonant component under test, and the resonant current of the secondary-side resonant component under test. It further calculates the impedance and establishes an impedance spectrum, compares it with a standard impedance spectrum, and determines the qualification status of the resonant component of the LCC-SS-T topology.

2. The test platform for LCC-SS-T topology based on impedance characteristic identification according to claim 1, characterized in that: Both voltage probes are high-voltage differential probes, and both current probes are high-frequency AC probes. The processing device is a computer. Both the voltage probes and the current probes receive data through the acquisition card of the test equipment, convert the continuous analog signal into discrete data points, and then transmit the processed digital signal to the computer through its data transmission interface.

3. The test platform for LCC-SS-T topology based on impedance characteristic identification according to claim 2, characterized in that: The PFC module is a single-phase Vienna topology.

4. The test platform for LCC-SS-T topology based on impedance characteristic identification according to claim 2, characterized in that: The secondary side test load module is a rectifier bridge module.

5. A test method for LCC-SS-T topology based on impedance characteristic identification, characterized in that: The testing method includes the testing platform as described in any one of claims 2-4, and the testing method includes the following steps: S1. Connect the input terminal of the primary side resonant component under test to the output port of the full-bridge converter; S2. Connect the output terminal of the secondary-side resonant cavity assembly under test to the input port of the secondary-side test load module; S3. Connect two voltage probes to the primary side resonant component under test and the secondary side resonant component under test respectively. The two voltage probes are used to measure the midpoint voltage of the primary side resonant component under test and the midpoint voltage of the secondary side resonant component under test respectively. Connect two current probes to the primary side resonant component under test and the secondary side resonant component under test respectively. The two current probes are used to measure the resonant current of the primary side resonant component under test and the resonant current of the secondary side resonant component under test respectively. S4. Connect both voltage probes and both current probes to the data acquisition card, and then connect it to the computer; S5. Turn on the grid power switch, and then turn on the PFC module and the primary inverter in sequence; S6. The primary inverter performs a frequency sweep operation, outputting a drive waveform from 40kHz to 200kHz. S7. The test equipment records the magnitude and phase of each key waveform during the frequency sweep and establishes an impedance model diagram; S8. Compare the impedance model diagram established during the frequency sweep with the standard impedance model diagram to determine the qualification status of the resonant components of the LCC-SS-T topology; S9. Turn off the primary inverter and PFC module, and finally turn off the grid power switch.

6. The test method for LCC-SS-T topology based on impedance characteristic identification according to claim 5, characterized in that: During the frequency sweep, the impedance model diagrams established include the input impedance spectrum of the LCC-SS-T topology within a certain frequency range, the output impedance spectrum of the LCC-SS-T topology within a certain frequency range, the equivalent impedance spectrum from the secondary side to the primary side of the LCC-SS-T topology within a certain frequency range, and the equivalent impedance spectrum from the primary side to the secondary side of the LCC-SS-T compensated topology within a certain frequency range.

7. The test method for LCC-SS-T topology based on impedance characteristic identification according to claim 6, characterized in that: The method for calculating the input impedance value using the resonant current of the primary-side resonant component under test and the magnitude and phase of the midpoint voltage of the primary-side resonant component under test is as follows: ， wherein Z p_in is the input impedance, V pi is the midpoint voltage of the primary side resonant assembly under test, i lrp is the resonant current of the primary side resonant assembly under test, φ p is the full-bridge phase-shift angle of the primary side resonant assembly under test, j is the imaginary unit, and ω is the angular frequency; The method for calculating the input impedance value using the resonant current of the secondary-side resonant component under test and the magnitude and phase of the midpoint voltage of the secondary-side resonant component under test is as follows: ， Z s_in V is the input impedance. si i is the midpoint voltage of the secondary-side resonant component under test. Ts φ is the resonant current of the secondary side resonant component under test. s θ is the full-bridge phase shift angle of the secondary-side resonant component under test. c It is the system phase difference, θ t It is the phase difference of the high-frequency transformer; The equivalent impedance from the secondary side to the primary side of the LCC-SS-T topology is calculated as follows: ， Z s_p This represents the equivalent impedance from the secondary side to the primary side, where the impedance used from the secondary side to the primary side is as follows: Z pi The ground-terminal resonant inductor branch impedance is the equivalent impedance of the resonant inductor branch viewed from the secondary side towards the ground. Z pr The impedance of the parallel capacitor branch at the ground terminal is the equivalent impedance of the parallel capacitor branch and other impedance components viewed from the secondary side to the ground terminal. Z prt The ground resonant coil branch impedance is the equivalent impedance of the resonant coil branch and other impedance components viewed from the secondary side towards the ground. Z prs The ground-to-vehicle resonant branch impedance is the equivalent impedance of the vehicle-end coil branch and other impedance components viewed from the secondary side to the ground. Z s_in :The input impedance at the vehicle end, the input impedance viewed from the secondary side towards the entire resonant cavity; The equivalent impedance from the primary side to the secondary side of the LCC-SS-T compensated topology is calculated as follows: ， Z p_s This is the equivalent impedance from the primary side to the secondary side. The impedance used from the primary side to the secondary side includes the following: Z srt The impedance of the resonant coil branch at the vehicle end is the equivalent impedance of the resonant coil branch and other impedance components viewed from the primary side towards the vehicle end. Z srp The impedance of the resonant branch from the vehicle end to the ground end is the equivalent impedance of the ground coil branch and other impedance components viewed from the primary side towards the vehicle end. Z srpt The impedance of the resonant transmitter branch from the vehicle end to the ground end is the equivalent impedance of the branch containing the leakage inductance and series capacitance of the ground coil and transmitter coil, as well as other impedance components, when viewed from the primary side towards the vehicle end. Z src The impedance of the parallel capacitor branch from the vehicle end to the ground end is the equivalent impedance of the parallel capacitor branch at the ground end as viewed from the primary side towards the vehicle end, along with other impedance components in front of it. Z p_in Ground input impedance, the input impedance viewed from the secondary side towards the entire resonant cavity.

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