A parameter testing method of LCC-SS-T topology based on voltage gain identification

Abstract

The application discloses a parameter test method for LCC-SS-T topology based on voltage gain identification, which is high in test efficiency, avoids parameter mutual interference and is accurate in judgment. The application comprises the following steps: S1, connecting the input end of a primary side to-be-tested resonant assembly to the output port of a primary side inverter; S2, connecting the output end of a secondary side to-be-tested resonant cavity assembly to the input port of a secondary side test responsible module; S3, connecting a voltage probe and one of high-frequency alternating current probes to the secondary side to-be-tested resonant assembly, and connecting a direct current probe and the other high-frequency alternating current probe to the secondary side to-be-tested resonant assembly; S4, connecting the four probes to a collection card and then connecting to a computer; S5, opening a power grid switch, and sequentially opening a PFC module and the primary side inverter; S6, performing a frequency sweeping operation on the primary side inverter, and outputting a driving waveform with a frequency of 40k to 200kHz; and S7, recording an output voltage gain spectrum during the frequency sweeping operation by a test device. The application is applied to the technical field of power electronics technology.

Description

Technical Field

[0001] This invention relates to a parameter testing method for an LCC-SS-T topology, and more particularly to a parameter testing method for an LCC-SS-T topology based on voltage gain 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 transmitting coil and compensation network, and the receiving 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 numerous 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 method for wireless charging systems based on LCC-SS-T topology using voltage gain identification, capable of quickly determining whether factory parameters meet standards by utilizing the characteristics of voltage gain, 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 parameter testing method for LCC-SS-T topology based on voltage gain identification that has high testing 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, which comprises test equipment and, in sequence, an electrically connected PFC module, a primary-side inverter, an LCC-SS-T topology, and a secondary-side test load module. The test equipment is electrically connected to both the LCC-SS-T topology and the secondary-side test load module. The LCC-SS-T topology consists of a primary-side resonant component under test and a secondary-side resonant component under test. The test equipment includes a voltage probe, a DC current probe, two high-frequency AC probes, a data acquisition card, and processing equipment. 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 primary-side inverter; S2. Connect the output terminal of the secondary-side resonant cavity assembly under test to the input port of the secondary-side test module; S3. Connect the voltage probe to the secondary side of the resonant component under test and collect the output voltage of the secondary side resonant component under test. Connect the DC current probe to the secondary side of the resonant component under test and collect the output current of the secondary side resonant component under test. The two high-frequency AC probes are used to collect 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 the voltage probe, DC current probe, and two high-frequency AC probes to the data acquisition card, and then connect them 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 output voltage gain spectrum during the frequency sweep and uses the voltage gain spectrum to determine the qualification status of the resonant components of the LCC-SS-T topology; S8. Turn off the primary inverter and PFC module, and finally turn off the grid power switch.

[0013] Furthermore, the primary-side resonant component under test includes an LCC transmitter topology; the secondary-side resonant component under test includes an SS receiver series resonant structure and a high-frequency transformer structure; the input terminal of the primary-side resonant component under test is connected to the output port of the primary-side inverter; the PFC module is 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; the output terminal of the secondary-side resonant component under test is connected to the input port of the secondary-side test module to receive energy transmitted from the primary side by the test platform.

[0014] Furthermore, the PFC module is a single-phase Vienna topology, the primary-side inverter is a full-bridge converter, and the secondary-side test load module is a rectifier bridge module.

[0015] Furthermore, the principle of the testing method is as follows: The voltage gain variation relationship for the LCC-SS-T topology is derived as follows: Output voltage of the full-bridge resonant component under test on the primary side:

[0016] Output voltage of the full-bridge resonant component under test on the secondary side: Among them, v Pi and v Si V represents the midpoint voltage of the full-bridge circuit for the primary and secondary resonant components under test, respectively. in and V out These are the input voltage of the primary inverter and the output voltage of the rectifier bridge module, respectively; n is the fundamental frequency; ω is the angular frequency of the operating frequency; t is time; φ p and φ s These are the modulation phase shift angles of the full bridge, θ and θ, respectively. c It is the system phase difference; Equivalent circuit analysis based on LCC-SS-T topology:

[0017]

[0018]

[0019] L in the formula rp C p C ps C s All are resonant parameters of the LCC-SS-T topology, C p C ps C s These parameters are all known values ​​after the resonant system under test is designed, and L rp C is the ground resonant inductor; p A capacitor connected in parallel to ground; C ps A capacitor connected in series with ground; C s M is the series capacitor at the vehicle end; M is the mutual inductance. Based on the three formulas for equivalent circuit analysis of the LCC-SS-T topology, the fundamental frequencies of the resonant voltage and resonant current received by the LCC-SS-T topology are:

[0020] in,

[0021]

[0022]

[0023]

[0024]

[0025] Among them, Z s_in It is the input impedance of the secondary-side resonant component under test; L p and L S ζ represents the self-inductance of the transmitting and receiving coils; M is the mutual inductance; Rp is the resistance of the ground coil; A / B / C / D are the elements of this calculation matrix; ζ is the coefficient of this calculation matrix; j is the imaginary unit; ω is the angular frequency; the amplitudes of the resonant voltage and resonant current of LCC-SS-T are:

[0026]

[0027] Then the output voltage V of the LCC-SS-T topology Out and output current I Out yes:

[0028]

[0029] Among them, the input resonant current I of this LCC-SS-T Lrp The expression is Among them, Z p_s It is the equivalent impedance from the primary side resonant component under test to the secondary side resonant component under test.

[0030] The LCC-SS-T has the characteristics of a constant voltage source, equivalent to a voltage source controlled by a voltage source, with the following voltage gain:

[0031] By G v_cv From the formula, we can see that the output voltage characteristic of this LCC-SS-T topology is independent of the load condition and has a constant voltage characteristic related to its own impedance characteristics. This constant voltage property will cause this resonant topology to have a certain frequency screening property. Therefore, by performing a frequency sweep at a certain frequency and observing the change in voltage gain, we can determine the rationality of its overall resonance.

[0032] Furthermore, the voltage probe is a high-voltage differential probe, and the processing device is a computer. The voltage probe, DC current probe, and high-frequency AC probe all 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.

[0033] The beneficial effects of this invention are: 1. High testing efficiency: Unlike traditional methods that require complex parameter detection at each frequency point, this invention can quickly obtain the output voltage gain spectrum through continuous frequency sweeping operations, resulting in a shorter testing process and greatly improving the testing efficiency of the production line.

[0034] 2. Avoid mutual interference of parameters: This invention does not require individual testing of the parameters of each resonant component. Instead, it identifies the pass or fail of resonant performance by the overall voltage gain change, thus avoiding mutual interference of resonant parameters.

[0035] 3. Accurate judgment: The output voltage gain spectrum is used to determine whether the parameters are qualified, which is simple and quick to operate. Attached Figure Description

[0036] 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 four key waveforms actually measured by the LCC-SS-T system in the embodiment; Figure 4 This is a schematic diagram showing the relationship between voltage gain and operating frequency. Detailed Implementation

[0037] In this embodiment, the present invention includes a test platform, which comprises test equipment and, in sequence, an electrically connected PFC module, a primary-side inverter, an LCC-SS-T topology, and a secondary-side test load module. The test equipment is electrically connected to both the LCC-SS-T topology and the secondary-side test load module. The LCC-SS-T topology consists of a primary-side resonant component under test and a secondary-side resonant component under test. The test equipment includes a voltage probe, a DC current probe, two high-frequency AC probes, a data acquisition card, and processing equipment. The primary-side resonant component under test includes an LCC transmitter topology; the secondary-side resonant component under test includes an SS receiver series resonant structure and a high-frequency transformer structure. The input terminal of the primary-side resonant component under test is connected to the output port of the primary-side inverter, and the output terminal of the secondary-side resonant component under test is connected to the input port of the secondary-side test load module. The secondary-side test load module receives energy transmitted from the primary side by the test platform. The PFC module is used to connect to the power grid for power factor correction and converts the AC power from the grid into DC power for input to the primary-side inverter. Additionally, the PFC module is a single-phase Vienna topology, the primary-side inverter is a full-bridge converter, and the secondary-side test load module is a rectifier bridge module. The voltage probe is a high-voltage differential probe, and the processing equipment is a computer. The voltage probe, DC current probe, and high-frequency AC probe all receive data through the test equipment's acquisition card, converting continuous analog signals into discrete data points, and then transmitting the processed digital signals to the computer through its data transmission interface. 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 primary-side inverter; S2. Connect the output terminal of the secondary-side resonant cavity assembly under test to the input port of the secondary-side test module; S3. Connect the voltage probe to the secondary side of the resonant component under test and collect the output voltage of the secondary side resonant component under test. Connect the DC current probe to the secondary side of the resonant component under test and collect the output current of the secondary side resonant component under test. The two high-frequency AC probes are used to collect 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 the voltage probe, DC current probe, and two high-frequency AC probes to the data acquisition card, and then connect them 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 output voltage gain spectrum during the frequency sweep and uses the voltage gain spectrum to determine the qualification status of the resonant components of the LCC-SS-T topology; S8. Turn off the primary inverter and PFC module, and finally turn off the grid power switch.

[0038] In this embodiment, the principle of the testing method is as follows: The voltage gain variation relationship for the LCC-SS-T topology is derived as follows: Output voltage of the full-bridge resonant component under test on the primary side:

[0039] Output voltage of the full-bridge resonant component under test on the secondary side: Among them, v Pi and v Si V represents the midpoint voltage of the full-bridge circuit for the primary and secondary resonant components under test, respectively. in and V out These are the input voltage of the primary inverter and the output voltage of the rectifier bridge module, respectively; n is the fundamental frequency; ω is the angular frequency of the operating frequency; t is time; φ p and φ s These are the modulation phase shift angles of the full bridge, θ and θ, respectively. c It is the system phase difference; Equivalent circuit analysis based on LCC-SS-T topology:

[0040]

[0041]

[0042] L in the formula rp C p C ps C s All are resonant parameters of the LCC-SS-T topology, C p C ps C s These parameters are all known values ​​after the resonant system under test has been designed, among which L rp yes Figure 1 Ground resonant inductance in C; p yes Figure 1 The ground terminal is connected in parallel with capacitor C; ps yes Figure 1 The ground terminal is connected in series with the capacitor; C s yes Figure 1 The series capacitor at the vehicle end; M is the mutual inductance.

[0043] Based on the three formulas for equivalent circuit analysis of the LCC-SS-T topology, the fundamental frequencies of the resonant voltage and resonant current received by the LCC-SS-T topology are:

[0044] in,

[0045]

[0046]

[0047]

[0048]

[0049] Among them, Z s_in It is the input impedance of the secondary-side resonant component under test; L p and L S ζ represents the self-inductance of the transmitting and receiving coils; M is the mutual inductance; the mutual inductance varies with factors such as coil position; Rp is the resistance of the ground coil; A / B / C / D are the elements of this calculation matrix; ζ is the coefficient of this calculation matrix; j is the imaginary unit; ω is the angular frequency. The amplitudes of the resonant voltage and resonant current of LCC-SS-T:

[0050]

[0051] Then the output voltage V of the LCC-SS-T topology Out and output current I Out yes:

[0052]

[0053] Among them, the input resonant current I of this LCC-SS-T Lrp The expression is Among them, Z p_s It is the equivalent impedance from the primary side resonant component under test to the secondary side resonant component under test.

[0054] The LCC-SS-T has the characteristics of a constant voltage source, equivalent to a voltage source controlled by a voltage source, with the following voltage gain:

[0055] By Gv_cv From the formula, we can see that the output voltage characteristic of this LCC-SS-T topology is independent of the load condition and has a constant voltage characteristic related to its own impedance characteristics. This constant voltage property will cause this resonant topology to have a certain frequency screening property. Therefore, by performing a frequency sweep at a certain frequency and observing the change in voltage gain, we can determine the rationality of its overall resonance.

[0056] In this embodiment, according to Figure 2 The test platform is shown, and then the test procedure S1-S8 is followed. The actual measured waveforms are shown below. Figure 3 As shown. Figure 3 The output voltage V of the secondary-side resonant component under test was recorded. out The output current I of the secondary-side resonant component under test out The resonant current i of the primary side resonant component under test lrp The resonant current i of the secondary side of the resonant component under test Ts This transient waveform temporarily represents the waveform under three different conditions. Among them, ① The waveform at the characteristic frequency shows the output current I. out Maintaining the maximum value, the output voltage V out Similar to the load; the resonant current i of the primary-side resonant component under test lrp The resonant current i of the secondary side of the resonant component under test Ts It exhibits a sinusoidal shape.

[0057] ② The waveform deviating from the characteristic frequency, and the output current I of the secondary side resonant component under test. out The voltage drops to zero because the output power decreases, therefore the output voltage V of the secondary-side resonant component under test decreases. out The voltage is pulled up to the output capacitor's potential (this is because the protection mechanism has been triggered); the resonant current i of the primary-side resonant component under test. lrp The resonant current i of the secondary side of the resonant component under test Ts It initially exhibits a sinusoidal shape, but it will attenuate when the frequency deviates to a certain extent.

[0058] ③ When the waveform deviates significantly from the characteristic frequency, the output current I out The output voltage V drops to zero. out The voltage will drop back to 0 as the output capacitor's potential decreases (this waveform only recorded 200 microseconds, so it's not visible). The output voltage decreases relatively slowly, taking tens of milliseconds to drop. The resonant current i of the primary-side resonant component under test. lrp The resonant current i of the secondary side of the resonant component under test Ts It is essentially zero.

[0059] By judging these three states, it is possible to quickly and qualitatively determine whether the resonance of the resonant cavity component matches the original design characteristic frequency.

[0060] The data acquisition card records the magnitude information of each waveform at each frequency point, mainly amplitude and phase, and sends it to a computer for recording and analysis. This yields the corresponding frequency-voltage gain spectrum, which can then assist engineers in further quantitative analysis.

[0061] The input voltage V of the primary inverter in Given a known value, the output voltage of the primary-side inverter typically remains constant. The proposed system simply performs a frequency sweep operation on this primary-side inverter within a certain frequency range. By directly measuring and recording the output voltage and frequency information, the output voltage can be determined. Figure 4 .

[0062] pass Figure 4 Voltage gain G v_cv The deviation from the operating frequency spectrum within a certain coupling coefficient and frequency range allows for rapid quantitative analysis of the resonant cavity component's qualification status.

[0063] This invention applies to the technical field of power electronics technology.

[0064] 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 parameter testing method for an LCC-SS-T topology based on voltage gain identification, characterized in that: The test platform includes test equipment and, in sequence, electrically connected components: a PFC module, a primary-side inverter, an LCC-SS-T topology, and a secondary-side test load module. The test equipment is electrically connected to both the LCC-SS-T topology and the secondary-side test load module. The LCC-SS-T topology consists of a primary-side resonant component under test and a secondary-side resonant component under test. The test equipment includes a voltage probe, a DC current probe, two high-frequency AC probes, a data acquisition card, and processing equipment. The primary-side resonant component under test includes the LCC transmitter topology. Secondary-side resonant components under test: including the SS receiver series resonant structure and the high-frequency transformer structure T; 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 primary-side inverter; S2. Connect the output terminal of the secondary-side resonant cavity assembly under test to the input port of the secondary-side test module; S3. Connect the voltage probe to the secondary side of the resonant component under test and collect the output voltage of the secondary side resonant component under test. Connect the DC current probe to the secondary side of the resonant component under test and collect the output current of the secondary side resonant component under test. The two high-frequency AC probes are used to collect 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 the voltage probe, DC current probe, and two high-frequency AC probes to the data acquisition card, and then connect them 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 output voltage gain spectrum during the frequency sweep and uses the voltage gain spectrum to determine the qualification status of the resonant components of the LCC-SS-T topology; S8. Turn off the primary inverter and PFC module, and finally turn off the grid power switch.

2. The parameter testing method for an LCC-SS-T topology based on voltage gain identification according to claim 1, characterized in that: Primary-side inverter: Connect the input terminal of the primary-side resonant component under test to the output port of the primary-side inverter; PFC module: Used to connect to the power grid for power factor correction and convert 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.

3. A parameter testing method for an LCC-SS-T topology based on voltage gain identification according to claim 2, characterized in that: The PFC module is a single-phase Vienna topology, the primary-side inverter is a full-bridge converter, and the secondary-side test load module is a rectifier bridge module.

4. A parameter testing method for an LCC-SS-T topology based on voltage gain identification according to claim 3, characterized in that: The principle of the testing method is as follows: The voltage gain variation relationship for the LCC-SS-T topology is derived as follows: Output voltage of the full-bridge resonant component under test on the primary side: ， Output voltage of the full-bridge resonant component under test on the secondary side: ， Among them, v Pi and v Si V represents the midpoint voltage of the full-bridge circuit for the primary and secondary resonant components under test, respectively. in and V out These are the input voltage of the primary inverter and the output voltage of the rectifier bridge module, respectively; n is the fundamental frequency; ω is the angular frequency; t is time; φ p and φ s These are the modulation phase shift angles of the full bridge, θ and θ, respectively. c It is the system phase difference; Equivalent circuit analysis based on LCC-SS-T topology: ， ， ， L in the formula rp C p C ps C s All are resonant parameters of the LCC-SS-T topology, C p C ps C s These parameters are all known values ​​after the resonant system under test is designed, and L rp C is the ground resonant inductor; p A capacitor connected in parallel to ground; C ps A capacitor connected in series with ground; C s M is the series capacitor at the vehicle end; M is the mutual inductance. Based on the three formulas for equivalent circuit analysis of the LCC-SS-T topology, the fundamental frequencies of the resonant voltage and resonant current received by the LCC-SS-T topology are: ， in, , ， ， ， ， Among them, Z s_in It is the input impedance of the secondary-side resonant component under test; L p and L S ζ represents the self-inductance of the transmitting and receiving coils; M represents the mutual inductance; Rp represents the resistance of the ground coil; A / B / C / D are the elements of this calculation matrix; ζ represents the coefficients of this calculation matrix; j represents the imaginary unit; ω represents the angular frequency. The amplitudes of the resonant voltage and resonant current of LCC-SS-T: ， ， Then the output voltage V of the LCC-SS-T topology Out and output current I Out yes: ， ， Among them, the input resonant current I of this LCC-SS-T Lrp The expression is ， Among them, Z p_s It is the equivalent impedance from the primary side resonant component under test to the secondary side resonant component under test; The LCC-SS-T has the characteristics of a constant voltage source, equivalent to a voltage source controlled by a voltage source, with the following voltage gain: ， By G v_cv From the formula, we can see that the output voltage characteristic of this LCC-SS-T topology is independent of the load condition and has a constant voltage characteristic related to its own impedance characteristics. This constant voltage property will cause this resonant topology to have a certain frequency screening property. Therefore, by performing a frequency sweep at a certain frequency and observing the change in voltage gain, we can determine the rationality of its overall resonance.

5. A parameter testing method for an LCC-SS-T topology based on voltage gain identification according to claim 1, characterized in that: The voltage probe is a high-voltage differential probe, and the processing device is a computer. The voltage probe, DC current probe, and high-frequency AC probe all 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.

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