A method and apparatus for measuring coil no-load loss based on LCC-LCC compensation network

Abstract

A method and apparatus for measuring coil no-load loss based on an LCC-LCC compensation network includes: Step 1, acquiring the output voltage of an inverter circuit, and using the fundamental, third, and fifth harmonic components of the output voltage to construct the input voltage parameters of the LCC-LCC compensation network; Step 2, using the mesh loop method, calculating the current parameter flowing through the internal resistance of the transmitting coil of the LCC-LCC compensation network based on the input voltage parameters; Step 3, calculating the no-load loss of the transmitting coil using the equivalent internal resistance and current parameters of the transmitting coil. This invention addresses the problem of inaccurate measurement of high-frequency electrical parameters in multi-physics environments of wireless charging systems, and achieves the measurement of coil no-load loss in wireless charging systems under high-frequency conditions.

Description

Technical Field

[0001] This invention belongs to the field of electrical parameter measurement technology, specifically relating to a method and device for measuring coil no-load loss based on an LCC-LCC compensation network. Background Technology

[0002] In the research of wireless power transfer technology, the operating frequency of the primary power supply is generally tens to hundreds of kHz. Therefore, the current and voltage signals coupled from the primary side to the secondary side through electromagnetic field resonance are also high-frequency signals of tens to hundreds of kHz. Due to the special topology of wireless charging with separate primary and secondary sides, and the secondary side being installed at the vehicle end, it is impractical to measure the electrical parameters on the DC output side of the secondary side. Therefore, the electrical parameters can only be measured on the AC side of the primary side.

[0003] In existing technologies, wireless power transfer is measured by measuring electrical parameters to calculate the electrical energy transferred from the primary side to the secondary side via coupled resonance. Therefore, it is necessary to measure the voltage and current signals of the wireless charging system to calculate the secondary side's electrical energy. The no-load loss of the transmitting coil is also a significant component of the electrical energy transferred from the primary to the secondary side. However, the methods for calculating coil no-load loss are either to first measure the current through the coil and then calculate the coil no-load loss from the known coil internal resistance, or to first measure the current and voltage through the coil and then calculate the coil no-load loss. Currently, electrical parameter measurement technology is still concentrated at the power frequency stage, while wireless charging systems rely on high-frequency resonance. The operating frequency of the primary power supply is generally tens to hundreds of kHz, and the primary and secondary current and voltage signals are also high-frequency signals of tens to hundreds of kHz. Furthermore, the compensation components and coupling coil cause the system to be filled with high-frequency harmonics, leading to distortion and jitter in the electrical parameters. Simultaneously, the cross-coupling between electromagnetic and thermal fields means that traditional measurement tools and methods can no longer meet the high-precision requirements under high-frequency conditions. Furthermore, instruments for measuring high-frequency electrical parameters require high-impedance inputs, while ordinary analog-to-digital converters (ADCs) have low-impedance inputs. Additionally, high-frequency detection is nonlinear, making it difficult to obtain functional relationships. All of these factors contribute to the extreme complexity of circuits for measuring high-frequency electrical parameters. Therefore, the problem of how to measure the no-load loss of the coil under high-frequency conditions needs to be solved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a coil no-load loss measurement method and device based on an LCC-LCC compensation network. This method addresses the problem of inaccurate measurement of high-frequency electrical parameters in wireless charging systems under multiple physical fields, and enables the measurement of coil no-load loss in wireless charging systems under high-frequency conditions.

[0005] The present invention adopts the following technical solution.

[0006] This invention proposes a method for measuring coil no-load loss based on an LCC-LCC compensation network, comprising:

[0007] Step 1: Acquire the output voltage of the inverter circuit, and use the fundamental component, third harmonic component and fifth harmonic component of the output voltage to construct the input voltage parameter of the LCC-LCC compensation network.

[0008] Step 2: Using the mesh loop method, calculate the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network based on the input voltage parameter;

[0009] Step 3: Calculate the no-load loss of the transmitting coil using the equivalent internal resistance and current parameters of the transmitting coil.

[0010] Preferably, step 1 includes:

[0011] Step 1.1, Measure the phase-shifted output voltage U of the inverter circuit. os Amplitude E and phase shift coefficient

[0012] Step 1.2: Based on the discrete-time continuous-frequency Fourier algorithm, using the amplitude E and phase shift coefficient... The input voltage u of the LCC-LCC compensation network is constructed. in The following relation is obtained:

[0013]

[0014] In the formula, ω0 is the fundamental angular frequency of the system when it is working, n is the harmonic order, which takes an odd value, and t is the time variable;

[0015] Step 1.3, from the input voltage u in The fundamental component, third harmonic component, and fifth harmonic component are extracted to form the input voltage parameters of the LCC-LCC compensation network.

[0016] Preferably, the phase shift coefficient satisfy

[0017] Preferably, the input voltage parameters are as follows:

[0018]

[0019] In the formula, Input voltage u in The effective value vector, i.e., the input voltage parameter.

[0020] Preferably, in step 2, the current flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network... The following relationship must be satisfied:

[0021]

[0022] In the formula,

[0023] C f1 This is the primary-side resonant capacitor.

[0024] ω is the angular frequency of the system during operation.

[0025] Preferably, the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network is obtained based on the input voltage parameter, satisfying the following relationship:

[0026]

[0027] In the formula, This is the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network.

[0028] Preferably, in step 3, the no-load loss of the transmitting coil is as follows:

[0029]

[0030] In the formula,

[0031] P is the no-load loss of the transmitting coil.

[0032] R1 is the equivalent internal resistance of the transmitting coil.

[0033] The present invention also proposes a coil no-load loss metering device based on an LCC-LCC compensation network, comprising: a data acquisition module, an input voltage parameter calculation module, a current parameter calculation module, and a transmitting coil no-load loss calculation module;

[0034] The acquisition module is used to acquire the output voltage of the inverter circuit;

[0035] The input voltage parameter calculation module is used to construct the input voltage parameters of the LCC-LCC compensation network using the fundamental component, third harmonic component and fifth harmonic component of the output voltage.

[0036] The current parameter calculation module is used to calculate the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network based on the input voltage parameter using the mesh loop method. The current parameter calculation module uses the current loop constructed by the mesh loop method, in which the analysis method of defining the reflection impedance is used. The reflection impedance is defined as the impedance obtained by the transmitter and receiver from the coupling respectively, and the coil is replaced by inductance and reflection impedance.

[0037] The no-load loss calculation module for the transmitting coil is used to calculate the no-load loss of the transmitting coil using the equivalent internal resistance and current parameters of the transmitting coil.

[0038] The beneficial effects of this invention are that, compared with the prior art, this invention proposes to decompose stray high-frequency electrical parameters from the perspective of time domain or frequency domain, decouple and quantitatively analyze each higher harmonic under high-frequency conditions, and compensate for the interference of electrical parameter measurement on wireless power transmission by analyzing the coupling relationship between the high-frequency characteristics of wireless power transmission electrical parameter measurement and higher harmonics, thereby achieving the scientific nature, accuracy and stability of measurement, which is conducive to ensuring the promotion and use of wireless charging systems for electric vehicles. Attached Figure Description

[0039] Figure 1 This is a flowchart of the coil no-load loss measurement method based on LCC-LCC compensation network proposed in this invention;

[0040] Figure 2 This refers to the inverter phase-shifted output voltage in this embodiment of the invention, i.e., the input voltage u of the LCC-LCC compensation network. in Waveform diagram;

[0041] Figure 2 The annotations in the accompanying drawings are explained as follows:

[0042] U os It is the inverter phase-shifted output voltage, ωt is the phase change of the inverter phase-shifted output voltage, and E and These are the amplitude and phase shift coefficient of the inverter's phase-shifted output voltage, respectively.

[0043] Figure 3 This is the equivalent circuit diagram of the LCC-LCC compensation network analyzed using the mesh loop method in this embodiment of the invention;

[0044] Figure 3 The annotations in the accompanying drawings are explained as follows:

[0045] v s - The effective value of the input voltage parameter of the LCC-LCC compensation network

[0046] L f1 - Primary resonant inductance, L f2 -Second-side resonant inductor, C f1 - Primary resonant capacitance, C f2 - Secondary resonant capacitor, L1 - Transmitting coil inductance, L2 - Receiving coil inductance, R1 - Equivalent internal resistance of transmitting coil, R2 - Equivalent internal resistance of receiving coil, R L - Equivalent load resistance, C1 - Primary side compensation capacitor, C2 - Secondary side compensation capacitor, M - Mutual inductance. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0048] This invention proposes a method for measuring coil no-load loss based on an LCC-LCC compensation network, applicable to wireless power transmission devices, such as... Figure 1 As shown, it includes:

[0049] Step 1: Acquire the output voltage of the inverter circuit, and use the fundamental component, third harmonic component and fifth harmonic component of the output voltage to construct the input voltage parameters of the LCC-LCC compensation network.

[0050] Step 1 includes:

[0051] Step 1.1, Measure the phase-shifted output voltage U of the inverter circuit. os Amplitude E and phase shift coefficient in

[0052] Specifically, such as Figure 2 As shown, the output voltage obtained by phase shifting the inverter circuit is measured, which is the input voltage u of the LCC-LCC compensation network. in Amplitude E and phase shift coefficient

[0053] Step 1.2: Based on the discrete-time continuous-frequency Fourier algorithm, using the amplitude E and phase shift coefficient... The input voltage u of the LCC-LCC compensation network is constructed. in The following relation is obtained:

[0054]

[0055] In the formula,

[0056] ω0 is the fundamental angular frequency of the system during operation.

[0057] n is the harmonic order, and its value is odd.

[0058] t is a time variable.

[0059] Therefore, the fundamental voltage gain G of the inverter circuit output os_1 for:

[0060]

[0061] Third harmonic voltage gain G os_3 Fifth harmonic voltage gain G os_5 7th harmonic voltage gain G os_7 Ninth harmonic voltage gain G os_9 They respectively satisfy the following relations:

[0062]

[0063]

[0064]

[0065]

[0066] The fundamental voltage, third harmonic voltage gain, fifth harmonic voltage gain, seventh harmonic voltage gain, ninth harmonic voltage gain, and phase shift coefficient of the inverter circuit output voltage are calculated. This is represented in a coordinate system. Therefore, according to the input voltage u of the LCC-LCC compensation network... in Considering the fundamental component, third harmonic component, and fifth harmonic component to construct the input voltage parameters of the LCC-LCC compensation network, the following relationship is satisfied:

[0067]

[0068] Step 2: Using the mesh loop method, calculate the current flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network.

[0069] Calculations were performed to obtain in Input voltage u in The effective value vector, C f1 This is the resonant capacitance of the primary side.

[0070] Specifically, current loops constructed using the mesh loop method, such as... Figure 3 As shown, the analysis method of defining the reflected impedance is used. The reflected impedance is defined as the impedance obtained by the transmitter and receiver from the coupling, and the coil is replaced by inductance and reflected impedance.

[0071] Primary resonant inductance L f1 One end is connected to the primary resonant capacitor C f1 One end of the primary-side compensation capacitor C1 is connected to one end of the transmitting coil inductor L1. The other end of the transmitting coil inductor L1 is connected to one end of the equivalent internal resistance R1 of the transmitting coil. The other end of the equivalent internal resistance R1 of the transmitting coil is connected to the primary-side resonant capacitor C. f1 At the other end, the effective value v of the input voltage parameter of the LCC-LCC compensation networks Applying a resonant inductance L to the primary side f1 The other end and the primary resonant capacitor C f1 The other end.

[0072] There is a mutual inductance M between the transmitting coil inductance L1 and the receiving coil inductance L2.

[0073] Secondary resonant inductor L f2 One end is connected to the secondary resonant capacitor C f2 One end of the secondary-side compensation capacitor C2 is connected to one end of the receiving coil inductor L2. The other end of the receiving coil inductor L2 is connected to one end of the equivalent internal resistance R2 of the receiving coil. The other end of the equivalent internal resistance R2 of the receiving coil is connected to the secondary-side resonant capacitor C. f2 At the other end, the secondary resonant inductor L f2 The other end is connected to the equivalent load resistance R. L One end, equivalent load resistance R L The other end is connected to the secondary resonant capacitor C. f2 The other end.

[0074] Step 3, take u from step 1.2 in effective value vector Substitute into step 2 The formula yields

[0075] Step 4, given R1 and C f1 , ω0, according to Obtain the no-load loss of the transmitting coil

[0076] In another aspect, this invention proposes a coil no-load loss metering device based on an LCC-LCC compensation network.

[0077] Includes: a data acquisition module, an input voltage parameter calculation module, a current parameter calculation module, and a transmitting coil no-load loss calculation module;

[0078] The acquisition module is used to acquire the output voltage of the inverter circuit;

[0079] The input voltage parameter calculation module is used to construct the input voltage parameters of the LCC-LCC compensation network using the fundamental component, third harmonic component and fifth harmonic component of the output voltage.

[0080] The current parameter calculation module is used to calculate the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network based on the input voltage parameter using the mesh loop method.

[0081] The no-load loss calculation module for the transmitting coil is used to calculate the no-load loss of the transmitting coil using the equivalent internal resistance and current parameters of the transmitting coil.

[0082] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0083] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0084] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0085] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for measuring coil no-load loss based on an LCC-LCC compensation network, characterized in that, include: Step 1: Acquire the output voltage of the inverter circuit, and use the fundamental component, third harmonic component and fifth harmonic component of the output voltage to construct the input voltage parameter of the LCC-LCC compensation network. Step 2: Using the mesh loop method, calculate the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network based on the input voltage parameter; Step 3: Calculate the no-load loss of the transmitting coil using the equivalent internal resistance and current parameters of the transmitting coil.

2. The coil no-load loss measurement method based on LCC-LCC compensation network according to claim 1, characterized in that, Step 1 includes: Step 1.1, Measure the phase-shifted output voltage U of the inverter circuit. os Amplitude E and phase shift coefficient Step 1.2: Based on the discrete-time continuous-frequency Fourier algorithm, using the amplitude E and phase shift coefficient... The input voltage u of the LCC-LCC compensation network is constructed. in The following relation is obtained: In the formula, ω0 is the fundamental angular frequency of the system when it is working, n is the harmonic order, which takes an odd value, and t is the time variable; Step 1.3, from the input voltage u in The fundamental component, third harmonic component, and fifth harmonic component are extracted to form the input voltage parameters of the LCC-LCC compensation network.

3. The coil no-load loss measurement method based on LCC-LCC compensation network according to claim 2, characterized in that, Phase shift coefficient satisfy 4. The coil no-load loss measurement method based on LCC-LCC compensation network according to claim 2, characterized in that, The input voltage parameters are as follows: In the formula, Input voltage u in The effective value vector, i.e., the input voltage parameter.

5. The coil no-load loss measurement method based on LCC-LCC compensation network according to claim 4, characterized in that, In step 2, the current flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network The following relationship must be satisfied: In the formula, C f1 This is the primary-side resonant capacitor. ω is the angular frequency of the system during operation.

6. The coil no-load loss measurement method based on LCC-LCC compensation network according to claim 5, characterized in that, The current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network is obtained from the input voltage parameter, and the following relationship is satisfied: In the formula, This is the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network.

7. The coil no-load loss measurement method based on LCC-LCC compensation network according to claim 6, characterized in that, In step 3, the no-load loss of the transmitting coil is as follows: In the formula, P is the no-load loss of the transmitting coil. R1 is the equivalent internal resistance of the transmitting coil.

8. A coil no-load loss metering device based on an LCC-LCC compensation network using the method described in any one of claims 1-7, characterized in that, The device includes: a data acquisition module, an input voltage parameter calculation module, a current parameter calculation module, and a transmitting coil no-load loss calculation module; The acquisition module is used to acquire the output voltage of the inverter circuit; The input voltage parameter calculation module is used to construct the input voltage parameters of the LCC-LCC compensation network using the fundamental component, third harmonic component and fifth harmonic component of the output voltage. The current parameter calculation module is used to calculate the current parameter flowing through the internal resistance of the transmitter coil of the LCC-LCC compensation network based on the input voltage parameter using the mesh loop method. The no-load loss calculation module for the transmitting coil is used to calculate the no-load loss of the transmitting coil using the equivalent internal resistance and current parameters of the transmitting coil.

9. The coil no-load loss metering device based on an LCC-LCC compensation network according to claim 8, characterized in that, The current parameter calculation module uses a mesh loop method to construct a current loop. It employs an analysis method that defines the reflected impedance, which is defined as the impedance obtained from the coupling at the transmitting and receiving ends, respectively. The coil is replaced with an inductor and the reflected impedance.

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