Series resonant wireless charging system with long cable
By using an EMI suppression inductor in a wireless charging system to form a high-impedance path with the parasitic inductance of long-distance cables, the electromagnetic interference problem caused by long-distance AC cables is solved, achieving compliance with electromagnetic compatibility standards and optimization of cost and size.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CARBON ZHIYUAN (SUZHOU) NEW ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2026-04-27
- Publication Date
- 2026-06-26
AI Technical Summary
In wireless charging systems, the high-frequency conducted and radiated noise caused by long-distance AC cables makes it difficult to meet international electromagnetic compatibility standards, and traditional solutions increase system cost and size.
A high-impedance path is formed by using an EMI suppression inductor, the parasitic inductance of the long-distance cable, and the inductance of the transmitting coil. High-frequency noise is suppressed by electric field communication at a set frequency. Chokes with EMI suppression inductance values of 200μH to 800μH are used to reduce radiated emissions.
It significantly suppresses high-frequency current components on long-distance cables, reduces electromagnetic interference, meets international electromagnetic compatibility standards, and avoids increases in cost and size.
Smart Images
Figure CN122292872A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to wireless charging technology, and more specifically to a series resonant wireless charging system with a long cable. Background Technology
[0002] Wireless charging technology, especially the series-in-series (SS) compensation architecture based on the principle of magnetic coupling resonance, has been widely used in wireless power supply for various electronic products, electric vehicles, and industrial equipment due to its simple structure and ease of control. In a typical SS architecture, the transmitting circuit (including the inverter and compensation capacitor) is directly connected to the transmitting coil through wires.
[0003] However, when applications require the transmitting coil to be separated from the transmitting circuit body, and the two need to be connected by an AC cable several meters long (for example, burying the transmitting coil in the ground or wall, or making it into a magnetic handle, while the driving circuit is placed in a remote control box), this long AC cable itself becomes part of the transmitting circuit. Because this cable has a large equivalent radiation area, the high-frequency harmonic current flowing on it will form an equivalent antenna effect, causing a sharp deterioration in the system's electromagnetic interference (EMI) characteristics, often failing to meet the testing requirements of international electromagnetic compatibility (EMC) standards (such as CISPR 11, CISPR 22, etc.). Traditional solutions usually involve adding a ferrite core or shielding layer to the cable, but this not only increases cost and size but also has limited effectiveness in suppressing common-mode interference in the low-frequency band. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to provide a series resonant wireless charging system with a long cable that effectively suppresses high-frequency conducted and radiated noise generated on long-distance AC cables without significantly increasing the system size and cost.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a series resonant wireless charging system with a long cable, including a transmitter assembly and a receiver assembly; The transmitter assembly includes an AC-DC converter connected to a power supply, a transmitter central processing unit (MCU), and an inverter. The transmitter MCU is connected to the AC-DC converter and the inverter via wires. The inverter includes an electric field communication feedback circuit module. The transmitter MCU is connected to the electric field communication feedback circuit module via power control signal lines and data signal lines. The electric field communication feedback circuit module is connected to the feedback electrode plate via wires. The transmitter assembly adjusts the DC input voltage through the AC-DC converter to change the current and magnetic field strength of the wireless charging transmitter coil. The receiver component includes a wireless charging receiving coil connected to a rectifier. The rectifier contains an electric field communication feedback circuit module, which is connected to the receiver's central processing unit (MCU) via a data signal line. The electric field communication feedback circuit module is connected to a feedback electrode plate via a wire. The rectifier is connected to a battery via a wire. The receiver's MCU has a control signal line connected to the rectifier via a wire connected to the battery. A capacitance of 1 pF or more is formed between the feedback electrode and the return electrode; the feedback electrode and the return electrode communicate unidirectionally from the receiving component side to the transmitting component side using a set frequency carrier wave. The inverter is connected to the adjustable transmitting capacitor via a wire, and the adjustable transmitting capacitor is connected to the EMI suppression inductor via a wire. The EMI suppression inductor is connected to the wireless charging transmitting coil via an AC cable with a length greater than 1 meter. The inductance value of the EMI suppression inductor is 200μH to 800μH.
[0006] As a preferred embodiment, the wireless charging receiving coil is connected to the receiving adjustable capacitor via a wire, and the receiving adjustable capacitor is connected to the rectifier via a wire.
[0007] As a preferred embodiment, the inductance value of the transmitting coil... The equivalent parasitic inductance value of the AC cable The inductance value of the EMI suppression inductor The capacitance value of the adjustable emission capacitor With system operating frequency The following relationship exists between them: .
[0008] As a preferred embodiment, the EMI suppression inductor is a choke with a magnetic core, the core being made of iron-silicon-aluminum, amorphous alloy, or ferrite.
[0009] As a preferred embodiment, the wireless charging system operates at a frequency of 20kHz to 200kHz.
[0010] As a preferred embodiment, the inductance value of the EMI suppression inductor is 300μH to 600μH.
[0011] As a preferred embodiment, the electric field communication feedback circuit module includes a feedback mixer and an amplifier to mix and amplify the data signal sent by the receiving end central processing unit MCU and the power control signal sent by the voltage-current comparator before transmitting it to the feedback electrode plate; the transmitting electrode plate transmits the signal to the feedback electrode plate through capacitive coupling. The electric field communication backhaul circuit module includes a preamplifier, a bandpass filter, and a backhaul mixer to input the signal received by the backhaul electrode to the transmitter's central processing unit (MCU).
[0012] As a preferred embodiment, the electric field communication backhaul circuit module is equipped with a high-impedance signal receiving / decoding circuit. The high-impedance signal receiving / decoding circuit separates the power control signal and data signal from the signal returned by the backhaul electrode and transmits them to the transmitter's central processing unit (MCU) to perform microsecond-level power adjustment on the wireless charging transmitting coil.
[0013] The beneficial effects of this invention are: Because of the inclusion of an EMI suppression inductor, the EMI suppression inductor, together with the parasitic inductance of the long-distance cable and the inductance of the transmitting coil, forms a high-impedance path. This path produces a significant attenuation effect on switching noise (i.e., the EMI noise band) above the resonant frequency, thereby greatly suppressing the high-frequency current component flowing through the AC cable and reducing radiated emissions.
[0014] The selection range of the inductance value for the EMI suppression inductor L_EMI should take into account the system operating frequency, cable length, and rated power. If the inductance value is too small, the noise suppression effect in the low-frequency range (<1MHz) will be insufficient; if the inductance value is too large, it may lead to excessive fundamental impedance, increase ineffective power loss, and may also make the inductor too large. Therefore, the inductance value of the EMI suppression inductor is 200μH to 800μH.
[0015] Due to the inductance of the transmitting coil The equivalent parasitic inductance value of the AC cable The inductance value of the EMI suppression inductor The capacitance value of the adjustable emission capacitor With system operating frequency The following relationship exists between them: At the system's operating frequency (fundamental resonant frequency, typically tens to hundreds of kHz), its impedance is relatively low; however, it exhibits high impedance for EMI noise above several MHz, demonstrating frequency selectivity and not affecting fundamental power transmission. Attached Figure Description
[0016] Figure 1 This is a circuit diagram of a series resonant wireless charging system with a long cable according to an embodiment of the present invention.
[0017] Figure 2 The graph shows a comparison of conducted EMI tests before and after using the circuit of this invention. Detailed Implementation
[0018] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0019] like Figure 1 As shown, a series resonant wireless charging system with a long cable includes a transmitter assembly and a receiver assembly. The transmitter assembly includes an AC-DC converter connected to a power supply, a transmitter central processing unit (MCU), and an inverter. The transmitter MCU is connected to the AC-DC converter and the inverter via wires. The inverter includes an electric field communication feedback circuit module. The transmitter MCU is connected to the electric field communication feedback circuit module via power control signal lines and data signal lines. The electric field communication feedback circuit module is connected to the feedback electrode plate via wires. The transmitter assembly adjusts the DC input voltage through the AC-DC converter to change the current and magnetic field strength of the wireless charging transmitter coil. The receiver component includes a wireless charging receiving coil, which is connected to a receiving adjustable capacitor via a wire. The receiving adjustable capacitor is connected to the rectifier via a wire. The rectifier includes an electric field communication feedback circuit module, which is connected to the receiver's central processing unit (MCU) via a data signal line. The electric field communication feedback circuit module is connected to a feedback electrode plate via a wire. The rectifier is connected to a battery via a wire. The receiver's MCU has a control signal line connected to the rectifier via a wire between the MCU and the battery.
[0020] A capacitance of 1 pF or more is formed between the feedback electrode and the return electrode; the feedback electrode and the return electrode communicate unidirectionally from the receiving component side to the transmitting component side using a set frequency carrier wave. The inverter is connected to the adjustable transmitting capacitor via a wire, which is then connected to the EMI suppression inductor via a wire. The EMI suppression inductor is connected to the wireless charging transmitting coil via a 3-meter-long AC cable. The transmitting coil 220 has an inductance of 50μH, the AC cable 230 has a parasitic inductance of approximately 2μH, and the EMI suppression inductor has an inductance of 470μH (capable of withstanding 20A DC bias without saturation). The original system operates at a frequency of 85kHz.
[0021] The inductance value of the transmitting coil The equivalent parasitic inductance value of the AC cable The inductance value of the EMI suppression inductor The capacitance value of the adjustable emission capacitor With system operating frequency The following relationship holds between (85kHz): Therefore, the capacitance value of the adjustable emitter capacitor Cs is adjusted to approximately 7.5 nF.
[0022] The electric field communication feedback circuit module includes a feedback mixer and an amplifier to mix and amplify the data signal sent by the receiving end central processing unit MCU and the power control signal sent by the voltage and current comparator, and then transmit them to the feedback electrode plate; the transmitting electrode plate transmits the signal to the feedback electrode plate through capacitive coupling. The electric field communication backhaul circuit module includes a preamplifier, a bandpass filter, and a backhaul mixer to input the signal received by the backhaul electrode to the transmitter's central processing unit (MCU).
[0023] The electric field communication backhaul circuit module is equipped with a high-impedance signal receiving / decoding circuit. The high-impedance signal receiving / decoding circuit separates the power control signal and data signal in the signal returned by the backhaul electrode and transmits them to the transmitter's central processing unit (MCU) to perform microsecond-level power adjustment on the wireless charging transmitter coil.
[0024] Actual testing revealed that, in a conventional architecture without an electromagnetic interference suppression inductor, conducted electromagnetic interference on a 3-meter AC cable exceeded the CISPR 11 Class B limit at multiple points in the 150kHz to 30MHz frequency band (e.g., exceeding 15dBμV at 2.1MHz).
[0025] By employing the circuit of this invention, the electromagnetic interference suppression inductor exhibits high impedance to high-frequency noise, significantly suppressing the high-frequency current flowing through the AC cable 230. Please refer to [link / reference]. Figure 2 Curve A represents the electromagnetic interference spectrum of the conventional architecture, and curve B represents the electromagnetic interference spectrum of the architecture of this invention. The results show that the electromagnetic interference value is reduced by an average of 12-18 dBμV at the main noise frequencies (1-10MHz), and the entire frequency band can pass the limits of CISPR 11 Class B (as shown by the dashed line).
[0026] The above embodiments are merely illustrative of the principles and effects of the present invention, as well as some examples of its application, and are not intended to limit the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention.
Claims
1. A series resonant wireless charging system with a long cable, comprising a transmitter assembly and a receiver assembly; The transmitter assembly includes an AC-DC converter connected to a power supply, a transmitter central processing unit (MCU), and an inverter. The transmitter MCU is connected to the AC-DC converter and the inverter via wires. The inverter includes an electric field communication feedback circuit module. The transmitter MCU is connected to the electric field communication feedback circuit module via power control signal lines and data signal lines. The electric field communication feedback circuit module is connected to the feedback electrode plate via wires. The transmitter assembly adjusts the DC input voltage through the AC-DC converter to change the current and magnetic field strength of the wireless charging transmitter coil. The receiver component includes a wireless charging receiving coil connected to a rectifier. The rectifier contains an electric field communication feedback circuit module, which is connected to the receiver's central processing unit (MCU) via a data signal line. The electric field communication feedback circuit module is connected to a feedback electrode plate via a wire. The rectifier is connected to a battery via a wire. The receiver's MCU has a control signal line connected to the rectifier via a wire connected to the battery. A capacitance of 1 pF or more is formed between the feedback electrode and the return electrode; the feedback electrode and the return electrode communicate unidirectionally from the receiving component side to the transmitting component side using a set frequency carrier wave. Its features are: The inverter is connected to the adjustable transmitting capacitor via a wire, and the adjustable transmitting capacitor is connected to the EMI suppression inductor via a wire. The EMI suppression inductor is connected to the wireless charging transmitting coil via an AC cable with a length greater than 1 meter. The inductance value of the EMI suppression inductor is 200μH to 800μH.
2. The series resonant wireless charging system with a long cable as described in claim 1, characterized in that: The wireless charging receiving coil is connected to the receiving adjustable capacitor via a wire, and the receiving adjustable capacitor is connected to the rectifier via a wire.
3. The series resonant wireless charging system with a long cable as described in claim 1, characterized in that: The inductance value of the transmitting coil The equivalent parasitic inductance value of the AC cable The inductance value of the EMI suppression inductor The capacitance value of the adjustable emission capacitor With system operating frequency The following relationship exists between them: .
4. The series resonant wireless charging system with a long cable as described in claim 1, characterized in that: The EMI suppression inductor is a choke with a magnetic core, which is made of iron-silicon-aluminum, amorphous alloy, or ferrite.
5. The series resonant wireless charging system with a long cable as described in claim 1, characterized in that: The wireless charging system operates at a frequency of 20kHz to 200kHz.
6. The series resonant wireless charging system with a long cable as described in claim 1, characterized in that: The inductance value of the EMI suppression inductor is 300μH to 600μH.
7. The series resonant wireless charging system with a long cable as described in claim 1, characterized in that: The electric field communication feedback circuit module includes a feedback mixer and an amplifier to mix and amplify the data signal sent by the receiving end central processing unit MCU and the power control signal sent by the voltage and current comparator, and then transmit them to the feedback electrode plate; the transmitting electrode plate transmits the signal to the feedback electrode plate through capacitive coupling. The electric field communication backhaul circuit module includes a preamplifier, a bandpass filter, and a backhaul mixer to input the signal received by the backhaul electrode to the transmitter's central processing unit (MCU).
8. A series resonant wireless charging system with a long cable as described in claim 1, characterized in that: The electric field communication backhaul circuit module is equipped with a high-impedance signal receiving / decoding circuit. The high-impedance signal receiving / decoding circuit separates the power control signal and data signal in the signal returned by the backhaul electrode and transmits them to the transmitter's central processing unit (MCU) to perform microsecond-level power adjustment on the wireless charging transmitter coil.