Emc optimized electric flame stove

Abstract

The application discloses an EMC-optimized electric flame cooker, which comprises a machine box, an EMI filter assembly, a power board, a shielding cover, a transformer, a resonant inductor, a voltage doubling rectifier board and a burner assembly installed on the machine box. The transformer and the resonant inductor are arranged in the same shielding cover, and the magnetic field excitation directions of the transformer and the resonant inductor are arranged in opposite directions, so that the magnetic fields are offset to each other, the resonant interference is inhibited, the interference energy forms a closed loop current in the shielding cover, is absorbed by the eddy current loss of the shielding cover metal body and is converted into heat energy to be radiated, and electromagnetic wave radiation is avoided. The base shielding of the all-metal machine box, the common shielding of the transformer and the resonant inductor, the independent shielding of the EMI filter assembly and the local shielding of the electrode needle are combined with the single-point grounding anti-ground loop design, so that the electromagnetic compatibility defects of the traditional electric flame cooker are solved from the root, and various test requirements of the national electromagnetic compatibility standards are met.

Description

Technical Field

[0001] This invention specifically relates to an electric flame stove. Background Technology

[0002] Existing electric flame stoves generally only focus on high-voltage electrical safety and structural insulation design, with significant shortcomings in electromagnetic compatibility. EMI filter circuits, high-voltage transformers, and resonant inductors are all high-frequency, high-voltage interference sources. During operation, they generate strong electromagnetic radiation and conducted interference, and are prone to resonant waveform distortion and interference energy superposition, causing interference to the main control circuit, PFC to inverter power supply circuit, and external environments.

[0003] For example, the invention patent with application number 2019106831779 discloses an electric flame stove, whose main control circuit board assembly includes a metal shield and a printed circuit board installed inside the metal shield. The metal shield avoids electromagnetic radiation affecting the circuits and components on the printed circuit board by reflecting the electromagnetic waves generated by the transformer.

[0004] However, the technical solutions of the aforementioned invention patents cannot truly solve the technical problem of electromagnetic compatibility. The electromagnetic waves generated by the high-frequency AC of the transformer still radiate to the outside world, affecting other components inside the chassis and external components or the human body, and cannot achieve the effect of electromagnetic compatibility.

[0005] If an independent shielding box is added to the transformer based on this technical solution, the electromagnetic waves radiated outward by the transformer during operation will be continuously reflected inside the shielding box and cannot be effectively dissipated. This will lead to a significant increase in the field strength inside the shielding box, energy accumulation, and the air inside the shielding box will be easily broken down. At the same time, the reflected high-frequency interference will be reverse-coupled back to the transformer windings, causing distortion of the working waveform, resonant point shift, and unstable high voltage output, affecting the stability of the electric flame stove. In addition, if the shielding box is grounded, the strong electric field generated inside the shielding box will be conducted to the main control board and power lines through the ground wire, forming large-area conducted interference and secondary electromagnetic radiation, and also polluting the power grid, making the electric flame stove unable to pass EMC certification. Summary of the Invention

[0006] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0007] An EMC-optimized electric flame stove includes a chassis, an EMI filter assembly, a power board, a shielding cover, a transformer, a resonant inductor, a voltage doubler rectifier board installed in the chassis, and a burner assembly installed on the chassis.

[0008] The chassis includes a shielded bottom shell and a shielded top shell that can be detachably installed on top of the shielded bottom shell; the EMI filter assembly, the power board, the shielding cover, the transformer, the resonant inductor, and the voltage doubler rectifier board are all fixed to the shielded top shell;

[0009] The transformer and the resonant inductor are placed together inside a shielding cover, and the shielding cover has ventilation openings on opposite sides for relative flow.

[0010] Preferably, the EMI filtering assembly consists of a shielding box and an EMI filter board placed inside the shielding box. The EMI filter board has two input wires of different polarities, and the section of the input wires located inside the chassis is wrapped with a shielding sleeve.

[0011] Preferably, the transformer and the resonant inductor are mounted on the same printed circuit board, and their magnetic field excitation directions are arranged in opposite directions.

[0012] Preferably, the shielding cover is grounded at a single point;

[0013] Preferably, an air intake grille is provided on one side wall of the shielding bottom shell, and multiple cooling fans are installed inside the air intake grille.

[0014] Preferably, the burner assembly includes a burner shield and a plurality of electrode needles disposed inside the burner shield, and the top surface of the burner shield is also provided with a plurality of negative electrode tubes corresponding to the electrode needles;

[0015] Preferably, the voltage multiplier rectifier board is provided with multiple voltage multiplier rectifier units corresponding to the electrode needles, as well as a resonant capacitor and a resonant resistor;

[0016] Preferably, the assembly process in which the transformer and the resonant inductor are mounted together on the same printed circuit board is as follows:

[0017] S1. A high-voltage insulated printed circuit board is selected. The board is pre-etched with special pads for transformers and resonant inductors, and traces are laid out. One of the traces directly connects the first end pad of the transformer's secondary winding to the pad of the nearby resonant inductor.

[0018] S2. The main winding coil of the transformer and the coil of the resonant inductor are custom-made with opposite winding directions to lock the magnetic field reversal characteristics.

[0019] S3. Precisely align and mount the transformer and resonant inductor to their respective pads.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] In this invention, the transformer and resonant inductor are placed together in the same shield, and their magnetic field excitation directions are arranged in opposite directions. The two, together with the resonant capacitor and resonant inductor, form a series resonant topology. Therefore, the high-frequency current flowing in the same phase eventually causes the high-frequency near-field magnetic field generated by the transformer's main winding and the high-frequency near-field magnetic field generated by the resonant inductor to form a magnetic field distribution with opposite phase and similar amplitude, realizing the reverse linkage of magnetic field lines. This achieves mutual cancellation of magnetic fields and mutual suppression of resonant interference. At the same time, the interference energy forms a closed loop inside the shield, which is absorbed by the eddy current loss of the shield metal body and converted into heat energy and dissipated, avoiding radiation to the outside in the form of electromagnetic waves.

[0022] This invention features a fully metal chassis with basic shielding, common shielding for the transformer and resonant inductor, independent shielding for the EMI filter components, and local shielding for the electrode needles. Combined with a single-point grounding anti-grounding loop design, it fundamentally solves the electromagnetic compatibility defects of traditional electric flame stoves and meets all the testing requirements of national electromagnetic compatibility standards.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a three-dimensional structural view of the present invention.

[0026] Figure 2 This is an exploded view of the structure of the present invention.

[0027] Figure 3 This is a structural diagram showing that the transformer and the resonant inductor are mounted together on the same printed circuit board. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] Furthermore, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0031] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] Please see Figures 1-2 In this embodiment of the invention, an EMC-optimized electric flame stove includes a chassis 1, an EMI filter assembly 2, a power board 3, a shielding cover 4, a transformer 5, a resonant inductor 6, a voltage doubler rectifier board 7 installed inside the chassis 1, and a burner assembly 8 installed on the chassis 1. The chassis 1 is an all-metal shielded structure, specifically including a shielding bottom shell 11 and a shielding top shell 12 detachably installed on the top of the shielding bottom shell 11. Both the shielding bottom shell 11 and the shielding top shell 12 are made of conductive metal. After assembly, they form a closed electromagnetic shielding cavity, which can effectively prevent electromagnetic interference inside the chassis 1 from leaking outward, and at the same time prevent external electromagnetic interference from entering the chassis 1 and affecting the operation of various components, thus providing basic electromagnetic shielding protection for the whole machine.

[0033] The chassis 1 includes a shielded bottom shell 11 and a shielded top shell 12 that can be detachably installed on top of the shielded bottom shell 11. The EMI filter assembly 2, power board 3, shielding cover 4, transformer 5, resonant inductor 6, and voltage doubler rectifier board 7 are all fixedly installed on the shielded top shell 12 by bolts. This assembly method enables the core components to form an integrated circuit module structure. Each component is suspended inside the shielded bottom shell 11 along with the shielded top shell 12, avoiding direct contact between the components and the shielded bottom shell 11, preventing short circuits caused by water accumulation, condensation, etc., and improving the safety of equipment use.

[0034] One of the core improvements in this embodiment is that the transformer 5 and the resonant inductor 6 are placed together in the same shield 4, forming a series resonant topology with the resonant capacitor and the resonant inductor 6. Therefore, the transformer 5 and the resonant inductor 6 are in phase with the current. The transformer 5 and the resonant inductor 6 are mounted together on the same printed circuit board 9, and their magnetic field excitation directions are arranged in opposite directions. They are mounted on the same printed circuit board 9 according to the principle of magnetic field reversal. Therefore, the magnetomotive force generated by the in-phase high-frequency current flowing through the two devices is opposite in direction. Ultimately, the high-frequency near-field magnetic field generated by the main winding of the transformer 5 and the high-frequency near-field magnetic field generated by the resonant inductor 6 form a magnetic field distribution with opposite phase and similar amplitude within the closed space defined by the shield 4, realizing the reverse linkage of magnetic field lines.

[0035] The magnetic field lines have similar amplitudes and are linked in opposite directions, which can achieve mutual cancellation of magnetic fields and mutual suppression of resonant interference. At the same time, the interference energy forms a closed loop inside the shield 4, which is absorbed by the eddy current loss of the metal body of the shield 4 and converted into heat energy and dissipated, thus avoiding radiation outward in the form of electromagnetic waves.

[0036] In this embodiment, the shielding cover 4 has symmetrically arranged ventilation openings 40 on both sides, which are directly opposite each other and form a through convection. The ventilation openings 40 are arranged in a straight line along the airflow direction of the shielding cover 4, forming a through directional air duct with the cooling fan and the air intake grille 10 of the chassis 1.

[0037] Furthermore, in a specific embodiment of the present invention, the EMI filter assembly 2 consists of a shielding box 21 and an EMI filter board 22 placed inside the shielding box 21. The shielding box 21 is made of conductive metal and can form electromagnetic shielding for the EMI filter board 22, preventing the filter board itself from being affected by external interference or radiating interference outward, thus ensuring the filtering effect. The EMI filter board 22 has two input wires of different polarities (not shown in the figure) for realizing the electrical connection between the mains power and the electric flame stove. The section of the input wire (not shown in the figure) located inside the chassis 1 is wrapped with a shielding sleeve (not shown in the figure). This shielding sleeve is a metal braided shielding sleeve and is reliably grounded to the shielding structure of the chassis 1. This can effectively prevent the unfiltered mains power input wire (not shown in the figure) from becoming a radiating antenna inside the chassis 1, and at the same time block the high-voltage resonant interference inside the chassis 1 from being conducted to the power grid along the input wire (not shown in the figure), thereby realizing bidirectional electromagnetic interference suppression between the power grid and the electric flame stove, and further improving the electromagnetic compatibility performance of the whole machine.

[0038] An air intake grille 10 is provided on one side wall of the shielding base shell 11. The air intake grille 10 has a louvered structure, which ensures airflow while preventing external debris and moisture from entering the chassis 1. Multiple cooling fans (not shown in the attached figure) are installed on the inner side of the air intake grille 10. When the cooling fans (not shown in the attached figure) are working, they draw ambient air from outside into the chassis 1 through the air intake grille 10, forming a directional cooling airflow. The airflow flows through the ventilation openings 40 of each core component and the shielding cover 4 in sequence, and finally exhausts the heat inside the chassis 1. This achieves comprehensive heat dissipation for all heat-generating components such as the EMI filter component 2, power board 3, transformer 5, resonant inductor 6, voltage doubler rectifier board 7, etc., ensuring that each component operates within the normal operating temperature range and avoiding performance degradation, reduced lifespan, or even burnout caused by overheating.

[0039] The burner assembly 8 is the electric flame generation unit of the electric flame stove, including a burner shield and multiple electrode needles disposed within the burner shield. The burner shield is made of conductive metal and is electrically connected to the shielding structure of the chassis 1 to form an integrated electromagnetic shield, which can effectively block the electromagnetic interference generated by the high-voltage discharge of the electrode needles from leaking outward, while preventing external interference from affecting the discharge stability of the electrode needles. The top surface of the burner shield is also provided with multiple negative electrode tubes corresponding to the electrode needles. The electrode needles cooperate with the corresponding negative electrode tubes to break down the air under high voltage to generate a plasma electric flame, thereby heating the cookware. The setting of the negative electrode tubes makes the electric flame generation more stable and the heating efficiency higher.

[0040] In a specific embodiment of the present invention, the voltage multiplier rectifier board 7 is provided with multiple voltage multiplier rectifier units corresponding to the electrode needles, as well as resonant capacitors and resonant resistors. The resonant capacitors and resonant resistors, together with the transformer 5 and the resonant inductor 6, form a complete high-voltage resonant rectifier circuit. Each voltage multiplier rectifier unit provides a stable high-frequency high voltage to the corresponding electrode needle, ensuring that the discharge of each electrode needle is uniform and the electric flame intensity is consistent. The resonant capacitors and resonant resistors are used to adjust the resonant frequency and impedance matching of the high-voltage resonant circuit, so that the circuit is always in the optimal resonant working state, avoiding waveform distortion and interference enhancement caused by resonant point offset, and further improving the working stability and electromagnetic compatibility performance of the electric flame stove.

[0041] This embodiment solves the electromagnetic compatibility (EMC) defects of traditional electric flame stoves from the root by using a basic shielding of an all-metal chassis 1, a common shielding of transformer 5 and resonant inductor 6, an independent shielding of EMI filter components 2, and a local shielding of electrode needles, combined with a single-point grounding anti-grounding loop design. It meets all the test requirements of the national EMC standard and ultimately achieves EMC certification.

[0042] In embodiments of the present invention, such as Figure 3 As shown, the assembly process for mounting the transformer 5 and the resonant inductor 6 together on the same printed circuit board 9 is as follows:

[0043] S1. A high-voltage insulated printed circuit board is selected. Dedicated pads for transformer 5 and resonant inductor 6 are pre-etched on the board. At the same time, traces 90 are laid. One of the traces 90 directly connects the first end pad of the secondary winding of transformer 5 to the nearby pad of resonant inductor 6.

[0044] S2. The main winding coil of transformer 5 and the coil of resonant inductor 6 are custom-made with opposite winding directions to lock the magnetic field reversal characteristics.

[0045] S3. Precisely align and mount the transformer 5 and the resonant inductor 6 to their respective pads.

[0046] Transformer 5 is wound clockwise, and resonant inductor 6 is wound counterclockwise, or both are wound in opposite directions, thus locking the magnetic field reversal characteristics at the coil structure level. Using the foolproof pads and positioning silkscreen on the PCB board as a reference, transformer 5 and resonant inductor 6 are precisely aligned and mounted to their corresponding pads. Even if resonant inductor 6 is rotated 180°, the relative relationship between the coil winding direction and the current flow direction remains unchanged, ensuring that the high-frequency near-field magnetic fields generated by the two are close in amplitude and opposite in phase.

[0047] The assembly process of mounting the transformer 5 and the resonant inductor 6 on the same printed circuit board 9 in this invention has the technical effect of 180° flip-tolerance. Therefore, the resonant inductor 6 does not need to be strictly distinguished in terms of installation direction, which improves the assembly efficiency.

[0048] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. An EMC-optimized electric flame stove, comprising a chassis, an EMI filter assembly, a power board, a shielding cover, a transformer, a resonant inductor, a voltage doubler rectifier board installed within the chassis, and a burner assembly installed on the chassis; characterized in that: The chassis includes a shielded bottom shell and a shielded top shell that can be detachably installed on top of the shielded bottom shell; the EMI filter assembly, the power board, the shielding cover, the transformer, the resonant inductor, and the voltage doubler rectifier board are all fixed to the shielded top shell; The transformer and the resonant inductor are both placed inside a shield, and their magnetic field excitation directions are arranged in opposite directions. The shielding cover has ventilation openings on opposite sides for relative flow, and the transformer and the resonant inductor are mounted on the same printed circuit board.

2. The EMC-optimized electric flame stove according to claim 1, characterized in that, The EMI filter assembly consists of a shielding box and an EMI filter board placed inside the shielding box. The EMI filter board has two input wires of different polarities, and the section of the input wires located inside the chassis is wrapped with a shielding sleeve.

3. The EMC-optimized electric flame stove according to claim 1, characterized in that, The shield is grounded at a single point.

4. The EMC-optimized electric flame stove according to claim 1, characterized in that, An air intake grille is provided on one side wall of the shielding bottom shell, and multiple cooling fans are installed inside the air intake grille.

5. The EMC-optimized electric flame stove according to claim 1, characterized in that, The burner head assembly includes a burner head shield and a plurality of electrode needles disposed inside the burner head shield. The top surface of the burner head shield is also provided with a plurality of negative electrode tubes corresponding to the electrode needles.

6. The EMC-optimized electric flame stove according to claim 5, characterized in that, The voltage multiplier rectifier board is equipped with multiple voltage multiplier rectifier units corresponding to the electrode needles, as well as resonant capacitors and resonant resistors.

7. The EMC-optimized electric flame stove according to claim 1, characterized in that, The assembly process for mounting the transformer and the resonant inductor together on the same printed circuit board is as follows: S1. A high-voltage insulated printed circuit board is selected. The board is pre-etched with special pads for transformers and resonant inductors, and traces are laid out. One of the traces directly connects the first end pad of the transformer's secondary winding to the pad of the nearby resonant inductor. S2. The main winding coil of the transformer and the coil of the resonant inductor are custom-made with opposite winding directions to lock the magnetic field reversal characteristics. S3. Precisely align and mount the transformer and resonant inductor to their respective pads.

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