A method for loss separation measurement and evaluation of a magnetic coupling mechanism component of a wireless charging system

Abstract

The application provides a kind of wireless charging system magnetic coupling mechanism component loss separation measurement evaluation method.The method obtains the loss of coil, magnetic core and aluminum shielding plate respectively by direct or indirect method, to verify the theoretical calculation model of loss, guide wireless charging product design.Compared with traditional disassembly test, the loss test can be completed without affecting the coupling characteristic parameters of magnetic coupling mechanism, and the test result is more accurate.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, and in particular relates to a method for measuring and evaluating the loss separation of magnetic coupling mechanism components in a wireless charging system. Background Technology

[0002] Wireless power transfer, or wireless charging technology, has been a research hotspot since its inception. With years of development, wireless charging technology has been widely applied in electric vehicles, electric ships, and implantable medical devices. Wireless charging is simple and convenient—just stop and start charging, requiring no manual operation and eliminating cables, greatly improving the user experience. Furthermore, wireless charging is unaffected by weather conditions, allowing for safe charging even in rain or snow. The rapid development of autonomous driving technology has further made in-vehicle wireless charging a necessity.

[0003] The magnetic coupling mechanism is a key component of inductive wireless charging systems, and its loss characteristics directly affect the transmission performance of the wireless charging system. High losses in the magnetic coupling mechanism can severely challenge the reliability of the system. This is especially true for high-power wireless charging systems for electric vehicles, where issues such as Litz coil burnout and ferrite core explosion can occur. Therefore, studying its loss characteristics is of great significance. The effective electrical structure of a magnetic coupling mechanism typically includes a Litz coil, a magnetic core, and an aluminum shield. These three components collectively influence the electromagnetic parameters of the magnetic coupling mechanism. Removing any one of them alters the overall coupling characteristics of the magnetic coupling mechanism, making it difficult to accurately separate and measure the losses of these three components under normal operating conditions using traditional testing methods.

[0004] Currently, the main research findings include:

[0005] A research team from Shanghai Jiao Tong University used a spiral coil structure as the research object, derived an analytical expression for the AC resistance of the coil based on a two-dimensional exact solution, and verified the correctness of the formula through experiments.

[0006] Zhejiang University studied the fitting method for the Steinmetz parameter and proposed an improved calculation formula to reduce the influence of magnetic flux density distribution and reduce calculation error.

[0007] North China Electric Power University has established a three-dimensional model of the coupling mechanism with a magnetic core and an aluminum plate, and calculated the losses of the magnetic core and aluminum plate.

[0008] The current research findings mainly suffer from the following technical problems:

[0009] 1. Existing methods can only estimate losses through theoretical calculations or finite element simulations, lacking experimental verification methods.

[0010] 2. Existing loss measurement methods can only measure the overall loss of the magnetic coupling mechanism, and cannot achieve accurate separate measurement of the loss of each component. Summary of the Invention

[0011] The purpose of this invention is to address the problems in existing technologies by proposing a method for separating and measuring the losses of magnetic coupling mechanism components in a wireless charging system. This method obtains the losses of the coil, magnetic core, and aluminum shielding plate directly or indirectly, thereby verifying the theoretical calculation model of the losses and guiding the design of wireless charging products.

[0012] This invention is achieved through the following technical solution: This invention proposes a method for measuring and evaluating the loss separation of magnetic coupling mechanism components in a wireless charging system, the method specifically being as follows:

[0013] Step 1: Start the system charging, record the system operating frequency, measure the voltage and current at the transmitting coil port and the receiving coil port respectively, record the transmitting coil current value, and calculate the active power at the transmitting coil port and the receiving coil port respectively. Subtract the two to obtain the overall loss of the magnetic coupling mechanism.

[0014] Step 2: Stop charging the system, disconnect the transmitter and receiver of the magnetic coupling mechanism, and use an LCR meter to test the internal resistance of the transmitter and receiver coils of the magnetic coupling mechanism at the operating frequency of the charging system. Calculate the coil loss of the magnetic coupling mechanism using the Joule heating formula.

[0015] Step 3: Reinstall the transmitting and receiving ends of the magnetic coupling mechanism, and arrange auxiliary measurement mechanisms on the back of the transmitting and receiving ends. The primary auxiliary mechanism is symmetrical about the aluminum plate, the transmitting coil, and the transmitting coil core, and is supplied with an excitation that is opposite in phase and equal to that of the transmitting coil. Similarly, the secondary auxiliary mechanism is symmetrical about the aluminum plate, the transmitting coil, and the transmitting coil core, and is supplied with an excitation that is opposite in phase and equal to that of the receiving coil through an auxiliary excitation device.

[0016] Step 4: Ensure that the excitation current and excitation frequency are the same, repeat Step 1, and subtract the measurement result of this step from the measurement result of Step 1 to obtain the aluminum shielding plate loss;

[0017] Step 5: Subtract the coil loss from the overall loss, and then subtract the aluminum plate loss to obtain the core loss.

[0018] Furthermore, the Joule heating formula is used to calculate the coil loss of the magnetic coupling mechanism as follows:

[0019] P coil =I 2 r (1).

[0020] Furthermore, the core loss is calculated using formula (2):

[0021] P core =PP coil -P shield (2).

[0022] The beneficial effects of this invention are as follows:

[0023] 1. It can realize the separate measurement of the losses of each component of the magnetic coupling mechanism, and can provide more detailed measurement and evaluation results.

[0024] 2. Compared with traditional disassembly and testing, loss testing can be completed with almost no impact on the coupling characteristic parameters of the magnetic coupling mechanism, resulting in more accurate test results. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the magnetic coupling mechanism.

[0026] Figure 2 This is a schematic diagram of the overall loss test of the magnetic coupling mechanism.

[0027] Figure 3 This is a schematic diagram of a loss testing system for magnetic coupling mechanism components. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Combination Figure 1 This invention proposes a method for measuring and evaluating the loss separation of magnetic coupling mechanism components in a wireless charging system. The method specifically comprises:

[0030] Step 1: Start the system charging, record the system operating frequency, measure the voltage and current at the transmitting coil port and the receiving coil port respectively, record the transmitting coil current value, and calculate the active power at the transmitting coil port and the receiving coil port respectively. Subtract the two to obtain the overall loss of the magnetic coupling mechanism.

[0031] Step 2: Stop charging the system, disconnect the transmitter and receiver of the magnetic coupling mechanism, and use an LCR meter to test the internal resistance of the transmitter and receiver coils of the magnetic coupling mechanism at the operating frequency of the charging system. Calculate the coil loss of the magnetic coupling mechanism using the Joule heating formula.

[0032] Step 3: Reinstall the transmitting and receiving ends of the magnetic coupling mechanism, and arrange auxiliary measurement mechanisms on the back of the transmitting and receiving ends. The primary auxiliary mechanism is symmetrical about the aluminum plate, the transmitting coil, and the transmitting coil core, and is supplied with an excitation that is opposite in phase and equal to that of the transmitting coil. Similarly, the secondary auxiliary mechanism is symmetrical about the aluminum plate, the transmitting coil, and the transmitting coil core, and is supplied with an excitation that is opposite in phase and equal to that of the receiving coil through an auxiliary excitation device.

[0033] Step 4: Ensure that the excitation current and excitation frequency are the same, repeat Step 1, and subtract the measurement result of this step from the measurement result of Step 1 to obtain the aluminum shielding plate loss;

[0034] Step 5: Subtract the coil loss from the overall loss, and then subtract the aluminum plate loss to obtain the core loss.

[0035] Example

[0036] This invention proposes a method for measuring and evaluating the loss separation of magnetic coupling mechanism components in a wireless charging system:

[0037] First, measure the overall loss of the magnetic coupling mechanism, start the system charging, record the system operating frequency, and follow the procedure as follows: Figure 2 The test was carried out as shown. Voltage and current were measured at the transmitting coil port and the receiving coil port respectively. The current value of the transmitting coil was recorded, and the active power of the transmitting coil port and the receiving coil port were calculated respectively. The difference between the two is the overall loss of the magnetic coupling mechanism when it is working.

[0038] Secondly, the losses of each component of the coupling mechanism are measured. First, the coil loss is measured. The internal resistance of the transmitting coil and receiving coil of the magnetic coupling mechanism is tested at the working frequency of the charging system using an LCR meter. The coil loss of the magnetic coupling mechanism is calculated using the Joule heating formula shown in formula (1).

[0039] P coil =I 2 r(1)

[0040] Secondly, the aluminum plate loss is measured, and the measurement method is as follows: Figure 3As shown, auxiliary mechanisms symmetrical about the aluminum shielding plate are arranged at the transmitting and receiving ends of the magnetic coupling mechanism. These mechanisms include auxiliary coils and auxiliary magnetic cores. Current excitation, opposite in phase and equal to that of the transmitting and receiving coils, is input into these auxiliary mechanisms, making the normal magnetic induction intensity on the aluminum plates at both ends approximately zero. Due to the planar structure of the aluminum shielding plate, the loss caused by the tangential magnetic induction intensity is relatively small and can be approximately ignored. Therefore, without affecting the coupling characteristics of the magnetic coupling mechanism, the aluminum shielding plate loss is almost completely suppressed. Then, by repeating the overall loss test procedure of the magnetic coupling mechanism while ensuring the same excitation current for the transmitting coil, and subtracting the test result from the overall loss of the magnetic coupling mechanism, the aluminum plate loss can be obtained.

[0041] Next, the core loss is calculated using formula (2). The core loss is obtained by subtracting the coil loss from the overall loss and then subtracting the aluminum plate loss.

[0042] P core =PP coil -P shield (2).

Claims

1. A method for measuring and evaluating the loss separation of magnetic coupling mechanism components in a wireless charging system, characterized in that: The method is specifically as follows: Step 1: Start the system charging, record the system operating frequency, measure the voltage and current at the transmitting coil port and the receiving coil port respectively, record the transmitting coil current value, and calculate the active power at the transmitting coil port and the receiving coil port respectively. Subtract the two to obtain the overall loss of the magnetic coupling mechanism. Step 2: Stop charging the system, disconnect the transmitter and receiver of the magnetic coupling mechanism, and use an LCR meter to test the internal resistance of the transmitter and receiver coils of the magnetic coupling mechanism at the operating frequency of the charging system. Calculate the coil loss of the magnetic coupling mechanism using the Joule heating formula. Step 3: Reinstall the transmitting and receiving ends of the magnetic coupling mechanism, and arrange auxiliary measurement mechanisms on the back of the transmitting and receiving ends. The primary auxiliary mechanism is symmetrical about the aluminum plate, the transmitting coil, and the transmitting coil core, and is supplied with an excitation that is opposite in phase and equal to that of the transmitting coil. Similarly, the secondary auxiliary mechanism is symmetrical about the aluminum plate, the transmitting coil, and the transmitting coil core, and is supplied with an excitation that is opposite in phase and equal to that of the receiving coil through an auxiliary excitation device. Step 4: Ensure that the excitation current and excitation frequency are the same, repeat Step 1, and subtract the measurement result of this step from the measurement result of Step 1 to obtain the aluminum shielding plate loss; Step 5: Subtract the coil loss from the overall loss, and then subtract the aluminum plate loss to obtain the core loss.

2. The method according to claim 1, characterized in that, The Joule heating formula is used to calculate the coil loss of the magnetic coupling mechanism as follows: P coil =I 2 r (1)。 3. The method according to claim 2, characterized in that, Calculate the core loss using formula (2): P core =P-P coil -P shield (2)。

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