Parameter test method of LCC-SS-T topology based on voltage gain identification

Abstract

The invention discloses an LCC-SS-T topology parameter testing method based on voltage gain recognition, which is high in testing efficiency, avoids mutual interference of parameters and is accurate in judgment. The method comprises the following steps: S1, connecting the input end of a primary-side to-be-tested resonant component to the output port of a primary-side inverter; s2, connecting the output end of the secondary side resonant cavity assembly to be tested to the input port of a secondary side test responsible module; s3, connecting the voltage probe and one of the high-frequency alternating-current probes to the secondary-side resonance assembly to be detected, and connecting the direct-current probe and the other high-frequency alternating-current probe to the secondary-side resonance assembly to be detected; s4, connecting the four probes to an acquisition card, and then connecting the acquisition card to a computer; s5, starting a power grid switch, and starting a PFC module and a primary side inverter in sequence; s6, performing frequency sweeping operation by the primary side inverter, and outputting a driving waveform with the frequency from 40k to 200kHz; and S7, the test equipment records an output voltage gain atlas during the frequency sweeping period. The invention is applied to the technical field of power electronic technology.

Description

Technical Field

[0001] The present invention relates to a parameter testing method for an LCC-SS-T topology, and in particular to a parameter testing method for an LCC-SS-T topology based on voltage gain identification. Background Art

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

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

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

[0005] Although the composite resonant topology significantly improves the robustness of wireless charging systems against parameter drift, there is still a key bottleneck in its large-scale production process: when the factory resonant parameters exceed the design tolerance range, it will cause the system's complex performance to deteriorate, ultimately resulting in batch quality defects in the product.

[0006] However, there are multiple resonant parameters within this composite resonant topology, which can affect the test results of individual parameters. Even after the resonant cavity assembly is installed, it is impossible to test these resonant parameters individually because test methods such as the Wheatstone bridge circuit are affected by other components within the resonant cavity assembly.

[0007] To ensure batch testing and verification of wireless charging systems before shipment, independent parameter testing of the resonant cavity components (including the transmitter coil and compensation network, the receiver coil, and the resonant compensation structure) is required. However, current testing methods have the following shortcomings:

[0008] 1. Inefficient testing: The resonant cavity assembly contains multiple components, requiring the multiple resonant inductors and capacitors to be individually disassembled for calibration and matching. Traditional methods require testing at each frequency point, resulting in a time-consuming testing process that cannot keep pace with the production line.

[0009] 2. Parameter Interference: Deviations in parameters such as coil inductance, resonant inductance, and series / shunt capacitance can have a cumulative impact. 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 can make it difficult to accurately locate the problematic component.

[0010] 3. Inaccurate judgment: Using current experience to judge whether the parameters are qualified can easily lead to misjudgment (judging components with hidden dangers as qualified).

[0011] Therefore, achieving a fast and accurate testing process remains a technical bottleneck that needs to be overcome. Therefore, developing a parameter testing method for wireless charging systems using the LCC-SS-T topology based on voltage gain identification, which can quickly determine whether factory parameters meet standards by utilizing the laws of voltage gain, has become a key requirement for improving the quality of wireless charging system mass production. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a parameter testing method for the LCC-SS-T topology based on voltage gain identification, which has high testing efficiency, avoids mutual interference of parameters and makes accurate judgments.

[0013] The technical solution adopted by the present invention is as follows: the present invention includes a test platform, the test platform includes a test device and a PFC module module, a primary-side inverter, an LCC-SS-T topology, and a secondary-side test load module electrically connected in sequence, the test devices are electrically connected to the LCC-SS-T topology and the secondary-side test load module, the LCC-SS-T topology is composed of a primary-side resonant component to be tested and a secondary-side resonant component to be tested; the test device includes a voltage probe, a DC current probe, two high-frequency AC probes, an acquisition card, and a processing device;

[0014] The test method includes the following steps:

[0015] S1. Connect the input of the primary-side resonant component to be tested to the output port of the primary-side inverter;

[0016] S2. Connect the output of the secondary-side resonant cavity component to the input port of the secondary-side test module.

[0017] S3. Connect the voltage probe to the secondary side resonant component to be measured and collect the output voltage of the secondary side resonant component to be measured, connect the DC current probe to the secondary side resonant component to be measured and collect the output current of the secondary side resonant component to be measured, and two high-frequency AC probes are used to collect the resonant current of the primary side resonant component to be measured and the resonant current of the secondary side resonant component to be measured;

[0018] S4. Connect the voltage probe, DC current probe, and two high-frequency AC probes to the acquisition card, and then to the computer.

[0019] S5. Turn on the grid switch, and then turn on the PFC module and the primary-side inverter;

[0020] S6. The primary-side inverter performs a frequency sweep operation, outputting a drive waveform from 40 kHz to 200 kHz.

[0021] S7. The test equipment records the output voltage gain spectrum during the frequency sweep and uses the voltage gain spectrum to determine whether the resonant component of the LCC-SS-T topology is qualified.

[0022] S8. Turn off the primary-side inverter and PFC module, and finally turn off the grid switch.

[0023] Furthermore, the resonant component to be tested on the primary side includes an LCC transmitter topology; the resonant component to be tested on the secondary side includes an SS receiver series resonant structure and a high-frequency transformer structure; the input end of the resonant component to be tested on the primary side 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 convert the AC power of the power grid into DC power and input it into the primary side inverter; the output end of the resonant component to be tested on the secondary side is connected to the input port of the secondary side test module for receiving energy transmitted from the primary side by the test platform.

[0024] 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.

[0025] Furthermore, the principle of the test method is as follows:

[0026] First, the voltage gain change relationship of the LCC-SS-T topology is derived as follows:

[0027] Output voltage of the full bridge of the resonant component to be tested on the primary side:

[0028]

[0029] Output voltage of the full bridge of the secondary side resonant component to be tested:

[0030]

[0031] Among them, v Pi and v Si are the midpoint voltages of the full bridges of the primary side resonant component to be measured and the secondary side resonant component to be measured respectively; V in and V outare the input voltage of the primary-side inverter and the output voltage of the rectifier bridge module respectively; n is the number of fundamental waves; ω is the angular frequency of the operating frequency; t is time; and are the modulation phase shift angle of the full bridge respectively; θ c is the system phase difference;

[0032] Equivalent circuit analysis based on LCC-SS-T topology:

[0033]

[0034] v Lp +jωMI s =(jωL p +R p )I Lp

[0035] jωMI Lp =Z s_in I s +v si

[0036] L in the formula rp , C p , C ps , C s are the resonance parameters of the LCC-SS-T topology, C p , C ps , C s These parameters are all known values after the resonant system to be tested is designed, and L rp is the ground resonant inductance; C p is the ground parallel capacitor; C ps C is the ground terminal series capacitor; s is the vehicle-end series capacitor; M is the mutual inductance;

[0037] According to the three formulas of the equivalent circuit analysis of the LCC-SS-T topology, the fundamental waves of the resonant voltage and resonant current received by the LCC-SS-T topology are:

[0038]

[0039] in,

[0040]

[0041]

[0042]

[0043]

[0044] Among them, Z s_in is the input impedance of the resonant component to be measured on the secondary side; L p and L S is the self-inductance of the transmitting coil and the receiving coil; 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 amplitude of the resonant voltage and resonant current of the LCC-SS-T is:

[0045]

[0046]

[0047] Then the output voltage V Out and output current I Out yes:

[0048]

[0049]

[0050] Among them, the input resonant current I of this LCC-SS-T is Lrp The expression is

[0051]

[0052] Among them, Z p_s It is the equivalent impedance from the primary-side resonant component to the secondary-side resonant component.

[0053] LCC-SS-T has the characteristics of a constant voltage source, which is equivalent to a voltage source controlled by a voltage source. Its voltage gain is:

[0054]

[0055] By G v_cv From the formula, we can know 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 characteristic. This constant voltage property causes 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 condition.

[0056] Furthermore, the voltage probe is a high-voltage differential probe, the processing device is a computer, and the voltage probe, DC current probe and high-frequency AC probe all receive data through the acquisition card of the test equipment, and convert the continuous analog signal into discrete data points, and then transmit the processed digital signal to the computer through its data transmission interface.

[0057] The beneficial effects of the present invention are: 1. High test efficiency: There is no need to perform complex parameter detection at each frequency point as in traditional methods; through continuous frequency sweeping operations, the output voltage gain spectrum can be quickly obtained, the test process takes less time, and the test efficiency of the production line is greatly improved.

[0058] 2. Avoiding mutual interference of parameters: The present invention does not need to test the parameters of each resonant component separately, but identifies whether the resonant performance is qualified or not through the overall voltage gain change, which can avoid mutual interference of resonant parameters.

[0059] 3. Accurate judgment: The output voltage gain spectrum is used to judge whether the parameters are qualified. The operation is simple and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a schematic diagram of the LCC-SS-T topology;

[0061] Figure 2 is a schematic diagram of the test platform;

[0062] Figure 3 Schematic diagram of four key waveforms actually measured by the LCC-SS-T system in the embodiment;

[0063] Figure 4 This is a diagram showing the relationship between voltage gain and operating frequency. DETAILED DESCRIPTION

[0064] In this embodiment, the present invention includes a test platform, which includes a test device and a PFC module, a primary-side inverter, an LCC-SS-T topology, and a secondary-side test load module electrically connected in sequence. The test devices are all electrically connected to the LCC-SS-T topology and the secondary-side test load module. The LCC-SS-T topology is composed of a primary-side resonant component to be tested and a secondary-side resonant component to be tested; the test device includes a voltage probe, a DC current probe, two high-frequency AC probes, an acquisition card, and a processing device; wherein the primary-side resonant component to be tested includes an LCC transmitter topology; the secondary-side resonant component to be tested includes an SS receiving-end series resonant structure and a high-frequency transformer structure; and the input end of the primary-side resonant component to be tested is connected to the output port of the primary-side inverter, and the output end of the secondary-side resonant component to be tested is connected to the input port of the secondary-side test module, and the secondary-side test module is used to receive energy transmitted from the primary side of the test platform; the PFC module is used to connect to the power grid for power factor correction and convert the AC power of the power grid into DC power and input it into the primary-side inverter;

[0065] In addition, 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 acquisition card of the test equipment and convert the continuous analog signal into discrete data points, and then transmit the processed digital signal to the computer through its data transmission interface.

[0066] The test method includes the following steps:

[0067] S1. Connect the input of the primary-side resonant component to be tested to the output port of the primary-side inverter;

[0068] S2. Connect the output of the secondary-side resonant cavity component to the input port of the secondary-side test module.

[0069] S3. Connect the voltage probe to the secondary side resonant component to be measured and collect the output voltage of the secondary side resonant component to be measured, connect the DC current probe to the secondary side resonant component to be measured and collect the output current of the secondary side resonant component to be measured, and two high-frequency AC probes are used to collect the resonant current of the primary side resonant component to be measured and the resonant current of the secondary side resonant component to be measured;

[0070] S4. Connect the voltage probe, DC current probe, and two high-frequency AC probes to the acquisition card, and then to the computer.

[0071] S5. Turn on the grid switch, and then turn on the PFC module and the primary-side inverter;

[0072] S6. The primary-side inverter performs a frequency sweep operation, outputting a drive waveform from 40 kHz to 200 kHz.

[0073] S7. The test equipment records the output voltage gain spectrum during the frequency sweep and uses the voltage gain spectrum to determine whether the resonant component of the LCC-SS-T topology is qualified.

[0074] S8. Turn off the primary-side inverter and PFC module, and finally turn off the grid switch.

[0075] In this embodiment, the principle of the test method is as follows:

[0076] First, the voltage gain change relationship of the LCC-SS-T topology is derived as follows:

[0077] Output voltage of the full bridge of the resonant component to be tested on the primary side:

[0078]

[0079] Output voltage of the full bridge of the secondary side resonant component to be tested:

[0080]

[0081] Among them, v Pi and v Si are the midpoint voltages of the full bridges of the primary side resonant component to be measured and the secondary side resonant component to be measured respectively; V in and V out are the input voltage of the primary-side inverter and the output voltage of the rectifier bridge module respectively; n is the number of fundamental waves; ω is the angular frequency of the operating frequency; t is time; and are the modulation phase shift angle of the full bridge respectively; θ c is the system phase difference;

[0082] Equivalent circuit analysis based on LCC-SS-T topology:

[0083]

[0084] v Lp +jωMI s =(jωL p +R p )I Lp

[0085] jωMI Lp =Z s_in I s +v si

[0086] L in the formula rp , C p , C ps , C s are the resonance parameters of the LCC-SS-T topology, C p , C ps , C s These parameters are all known values after the resonant system to be tested is designed, among which L rp yes Figure 1 The ground resonant inductance in the p yes Figure 1 The ground parallel capacitor in the ps yes Figure 1 The ground terminal series capacitor in the circuit; C s yes Figure 1 The vehicle-end series capacitor in the figure is M, which is the mutual inductance.

[0087] According to the three formulas of the equivalent circuit analysis of the LCC-SS-T topology, the fundamental waves of the resonant voltage and resonant current received by the LCC-SS-T topology are:

[0088]

[0089] in,

[0090]

[0091]

[0092]

[0093]

[0094] Among them, Z s_in is the input impedance of the resonant component to be measured on the secondary side; L p and L S is the self-inductance of the transmitting coil and the receiving coil; M is the mutual inductance; the mutual inductance varies with factors such as the position of the coils; 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;

[0095] The amplitude of the resonant voltage and resonant current of LCC-SS-T:

[0096]

[0097]

[0098] Then the output voltage V Out and output current I Out yes:

[0099]

[0100]

[0101] Among them, the input resonant current I of this LCC-SS-T is Lrp The expression is

[0102]

[0103] Among them, Z p_s It is the equivalent impedance from the primary-side resonant component to the secondary-side resonant component.

[0104] LCC-SS-T has the characteristics of a constant voltage source, which is equivalent to a voltage source controlled by a voltage source. Its voltage gain is:

[0105]

[0106] By G v_cvFrom the formula, we can know 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 characteristic. This constant voltage property causes 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 condition.

[0107] In this embodiment, according to Figure 2 The test platform is shown in the figure, and then the test process of S1-S8 is carried out. The actual measured waveform is shown in the figure Figure 3 As shown. Figure 3 Record the output voltage V of the secondary side resonant component to be tested out , the output current I of the secondary side resonant component to be measured out , the resonant current i of the resonant component to be measured on the primary side lrp and the resonant current i of the secondary side resonant component to be measured Ts The transient waveform temporarily shows the waveforms in three cases.

[0108] ① In the waveform at the characteristic frequency, we can see the output current I out Maintain the maximum value, output voltage V out Same as the load; the resonant current i of the resonant component to be measured on the primary side lrp and the resonant current i of the secondary side resonant component to be measured Ts Sinusoidal in shape.

[0109] ② The waveform deviates from the characteristic frequency, and the output current I out Drops to zero, because the output power becomes lower, so the output voltage V out is pulled up to the potential of the output capacitor (this is because the protection mechanism is triggered); the resonant current i lrp and the resonant current i of the secondary side resonant component to be measured Ts In the early stage, it still presents a sinusoidal shape, but when the frequency deviation reaches a certain level, it will attenuate.

[0110] ③ The waveform seriously deviates from the characteristic frequency, and the output current I out drops to zero, the output voltage V out The resonant current i of the resonant component to be tested on the primary side is lrp and the resonant current i of the secondary side resonant component to be measured Ts Basically zero.

[0111] Basically, by judging these three states, it is possible to quickly and qualitatively determine whether the resonance of the resonant cavity component is consistent with the originally designed characteristic frequency.

[0112] The acquisition card records the size information of each waveform at each frequency point, mainly the amplitude and phase, and sends it to the computer for recording and analysis. The corresponding frequency-voltage gain spectrum is obtained, which can help engineers perform further quantitative analysis.

[0113] The input voltage of the primary side inverter is V in The output voltage of the primary side inverter is a known value. Usually, the output voltage of the primary side inverter does not change. The proposed system only allows the primary side inverter to perform frequency sweep operation within a certain frequency range. By directly measuring and recording the output voltage and frequency information, the Figure 4 .

[0114] pass Figure 4 Voltage gain G v_cv The deviation from the operating frequency spectrum within a certain coupling coefficient and frequency range can quickly and quantitatively analyze the qualification of the resonant cavity component.

[0115] The present invention is applied to the technical field of power electronics technology.

[0116] Although the embodiments of the present invention are described with practical solutions, they do not limit the meaning of the present invention. For those skilled in the art, it is obvious to modify the implementation scheme and combine it with other solutions based on this description.

Claims

1. A parameter testing method for an LCC-SS-T topology based on voltage gain identification, characterized by: The test platform includes a test device and a PFC module, a primary-side inverter, an LCC-SS-T topology, and a secondary-side test load module electrically connected in sequence. The test devices are electrically connected to the LCC-SS-T topology and the secondary-side test load module. The LCC-SS-T topology is composed of a primary-side resonant component to be tested and a secondary-side resonant component to be tested. The test device includes a voltage probe, a DC current probe, two high-frequency AC probes, an acquisition card, and a processing device. The test method includes the following steps: S1. Connect the input of the primary-side resonant component to be tested to the output port of the primary-side inverter; S2. Connect the output of the secondary-side resonant cavity component to the input port of the secondary-side test module. S3. Connect the voltage probe to the secondary side resonant component to be measured and collect the output voltage of the secondary side resonant component to be measured, connect the DC current probe to the secondary side resonant component to be measured and collect the output current of the secondary side resonant component to be measured, and two high-frequency AC probes are used to collect the resonant current of the primary side resonant component to be measured and the resonant current of the secondary side resonant component to be measured; S4. Connect the voltage probe, DC current probe, and two high-frequency AC probes to the acquisition card, and then to the computer. S5. Turn on the grid switch, and then turn on the PFC module and the primary-side inverter; S6. The primary-side inverter performs a frequency sweep operation, outputting a drive waveform from 40 kHz to 200 kHz. S7. The test equipment records the output voltage gain spectrum during the frequency sweep and uses the voltage gain spectrum to determine whether the resonant component of the LCC-SS-T topology is qualified. S8. Turn off the primary-side inverter and PFC module, and finally turn off the grid switch.

2. A parameter testing method for an LCC-SS-T topology based on voltage gain identification according to claim 1, characterized in that: The resonant component to be tested on the primary side: including the LCC transmitter topology; Secondary side resonant components to be tested: including the SS receiving end series resonant structure and high-frequency transformer structure; Primary-side inverter: Connect the input of the primary-side resonant component to be tested to the output port of the primary-side inverter; PFC module: used to connect to the grid for power factor correction and convert the AC power of the grid into DC power and input it into the primary side inverter; Secondary side test load module: The output end of the secondary side resonant component to be tested is connected to the input port of the secondary side test module to receive the 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 test method is as follows: First, the voltage gain change relationship of the LCC-SS-T topology is derived as follows: Output voltage of the full bridge of the primary side resonant component to be tested: Output voltage of the full bridge of the secondary side resonant component to be tested: Among them, v Pi and v Si are the midpoint voltages of the full bridges of the primary side resonant component to be measured and the secondary side resonant component to be measured respectively; V in and V out are the input voltage of the primary-side inverter and the output voltage of the rectifier bridge module respectively; n is the number of fundamental waves; ω is the angular frequency; t is time; and are the modulation phase shift angle of the full bridge respectively; θ c is the system phase difference; Equivalent circuit analysis based on LCC-SS-T topology: v Lp +jωMI s =(jωL p +R p )I Lp jωMI Lp =Z s_in AND s +v si L in the formula rp , C p , C ps , C s are the resonance parameters of the LCC-SS-T topology, C p , C ps , C s These parameters are all known values after the resonant system to be tested is designed, and L rp is the ground resonant inductance; C p is the ground parallel capacitor; C ps C is the ground terminal series capacitor; s is the vehicle-end series capacitor; M is the mutual inductance; according to the three formulas of the equivalent circuit analysis of the LCC-SS-T topology, the fundamental waves of the resonant voltage and resonant current received by the LCC-SS-T topology are: in, Among them, Z s_in is the input impedance of the resonant component to be measured on the secondary side; L p and L S is the self-inductance of the transmitting coil and the receiving coil; 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 amplitude of the resonant voltage and resonant current of LCC-SS-T: Then the output voltage V Out and output current I Out yes: Among them, the input resonant current I of this LCC-SS-T is Lrp The expression is Among them, Z p_s It is the equivalent impedance from the primary side resonant component to the secondary side resonant component. LCC-SS-T has the characteristics of a constant voltage source, which is equivalent to a voltage source controlled by a voltage source. Its voltage gain is: By G v_cv From the formula, we can know 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 characteristic. This constant voltage property causes 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 condition.

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, and convert the continuous analog signal into discrete data points, and then transmit the processed digital signal to the computer through its data transmission interface.

Images