Lightning stroke protection circuit of electromagnetic heating device

Abstract

The utility model discloses a lightning stroke protection circuit of an electromagnetic heating device, which comprises an over-current, over-voltage and interference suppression circuit, a rectification filter circuit and a resonance heating circuit which are connected in sequence, the over-current, over-voltage and interference suppression circuit comprises a fuse FS01, a piezoresistor RZ01, a piezoresistor RZ02, a filter capacitor CX01 and a filter inductor L1, wherein the AC-L of the alternating current is sequentially connected with the fuse FS01 and the piezoresistor RZ01 in series to return to the AC-N, the AC-L of the alternating current is connected with the filter inductor L01 and the piezoresistor RZ02 in series to return to the AC-N, and the filter capacitor CX01 is connected with the piezoresistor RZ02 in parallel; the resonance heating circuit comprises a wire coil, a resonance capacitor CXZ30, an IGBT 30 and a TVS tube group. According to the utility model, two groups of piezoresistors are adopted in the overcurrent, overvoltage and interference suppression circuit, and a filter inductor is arranged in front, so that the protection response speed is improved, the effects of reducing voltage and clamping high voltage are achieved, the lightning stroke protection on a bridge rectifier is improved, and the IGBT of the resonance heating circuit is connected in parallel with a TVS tube group, so that the lightning stroke protection on the IGBT is improved, and the service life of the resonance heating circuit is prolonged. Therefore, the overall lightning protection of the electromagnetic heating device is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic heating, in particular to a lightning protection circuit for an electromagnetic heating device. Background Art

[0002] In the use of electromagnetic heating devices, abnormal voltage fluctuations are very destructive to the device. When the current with excessively high voltage enters the circuit of the device, it will damage the rectifier bridge stack, insulated gate bipolar transistor (IGBT), etc., and in severe cases, it will directly cause the electromagnetic heating device to be completely scrapped.

[0003] In the prior art, a varistor is set at the power input end of the electromagnetic heating device, and an inductor is set at the rectifier bridge stack of the electromagnetic heating device to overcome the impact damage of the rectifier bridge stack and the IGBT caused by high voltage. However, when the current of 4KV voltage generated by lightning strike flows into the electromagnetic heating device, the varistor set at the power input end and the inductor of the rectifier bridge stack cannot overcome the high voltage generated by lightning strike, thereby causing damage to the rectifier bridge stack and the IGBT. Utility Model Content

[0004] The purpose of the utility model is to provide a lightning protection circuit for an electromagnetic heating device to solve the problem that when a current with a voltage of 4KV generated by a lightning strike flows into the electromagnetic heating device, the varistor and the inductance of the rectifier bridge stack arranged at the power input end cannot overcome the high voltage generated by the lightning strike, thereby causing damage to the rectifier bridge stack and the IGBT, so as to overcome the shortcomings of the prior art.

[0005] The utility model provides a lightning protection circuit for an electromagnetic heating device through the following technical scheme, including an overcurrent, overvoltage and interference suppression circuit, a rectifier filter circuit and a resonant heating circuit connected in sequence; the overcurrent, overvoltage and interference suppression circuit includes a fuse FS01, a varistor RZ01, a varistor RZ02, a filter capacitor CX01 and a filter inductor L1, wherein the AC-L of the alternating current is connected in series with the fuse FS01 and the varistor RZ01 in sequence and then returns to AC-N, and the AC-L of the alternating current is connected in series with the filter inductor L01 and the varistor RZ02 returns to AC-N, the filter capacitor CX01 is connected in parallel with the varistor RZ02, and the two ends of the filter capacitor CX01 are used as the output ends of the overcurrent, overvoltage and interference suppression circuit to connect the rectifier and filter circuit; the resonant heating circuit includes a wire drum, a resonant capacitor CXZ30, an IGBT30 and a TVS tube group, the resonant capacitor CXZ30 and the IGBT30 are connected in series between the two output ends OUT1 and OUT2 of the rectifier and filter circuit, the wire drum is connected in parallel with the resonant capacitor CXZ30, and the TVS tube group is connected in parallel with the IGBT30.

[0006] Furthermore, the TVS tube group includes TVS1, TVS2 and TVS3.

[0007] The utility model has the following beneficial effects: two groups of varistors are used in the overcurrent, overvoltage and interference suppression circuits, and the filter inductor is placed in front, so as to improve the protection response speed, achieve the effect of reducing the voltage and clamping the high voltage, improve the lightning protection of the rectifier bridge stack, and connect the TVS tube group in parallel to the IGBT of the resonant heating circuit to improve the lightning protection of the IGBT, thereby improving the overall lightning protection of the electromagnetic heating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The utility model discloses a circuit diagram of an overcurrent, overvoltage and interference suppression circuit and a rectifier and filter circuit of a lightning protection circuit of an electromagnetic heating device.

[0009] Figure 2 The present invention is a circuit diagram of a resonant heating circuit of a lightning protection circuit of an electromagnetic heating device. DETAILED DESCRIPTION

[0010] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0011] The components of the embodiments of the present application generally described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the application claimed, but merely represents the selected embodiments of the present application.

[0012] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0013] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0014] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0015] Refer to the following Figure 1-2 A lightning protection circuit for an electromagnetic heating device according to some embodiments of the present application is described.

[0016] The technical solution provides a lightning protection circuit for an electromagnetic heating device, comprising an overcurrent, overvoltage and interference suppression circuit, a rectifier and filter circuit and a resonant heating circuit connected in sequence.

[0017] The overcurrent, overvoltage and interference suppression circuit includes fuse FS01, varistor RZ01, varistor RZ02, filter capacitor CX01 and filter inductor L1, wherein AC-L of the alternating current is connected in series with fuse FS01 and varistor RZ01 in sequence and returns to AC-N, AC-L of the alternating current is connected in series with filter inductor L01 and varistor RZ02 and returns to AC-N, filter capacitor CX01 is connected in parallel with varistor RZ02, and both ends of filter capacitor CX01 are used as output ends of the overcurrent, overvoltage and interference suppression circuit for connecting the rectifier filter circuit; FS01 is a 12A fuse (commonly known as a fuse), when the current flowing through exceeds 12A, the fuse will immediately blow and open the circuit to protect the subsequent circuit from being burned by the large current. When the varistor RZ01 and the varistor RZ02 encounter high voltage, RZ01 and RZ02 will immediately break down and short-circuit, generating a large current flowing through RV, causing the fuse FS011 to melt due to the large current passing through, thereby preventing the high voltage from damaging the subsequent circuit. CX01 is a high-frequency filter capacitor that can filter out high-frequency interference pulses. For example, when the L line is mixed with high-frequency interference pulses, it will reach the N line through CX01 and disappear, thereby preventing it from entering the subsequent circuit. In addition, if the high-frequency interference pulse generated by the subsequent circuit reaches the L line, it will reach the N line through CX01 and disappear, preventing it from entering the public power grid to interfere with other electrical appliances.

[0018] The rectifier and filter circuit includes a rectifier bridge stack DB01 and a filter capacitor CX02. The four diodes inside the rectifier bridge stack DB01 are connected to form a bridge rectifier circuit, and four pins AC(2), AC(3), +(1), and -(4) are led out to the outside. The two AC pins are connected to the output voltage of the overcurrent, overvoltage, and interference suppression circuits. After internal rectification, a pulsating DC voltage of about 310V is output from the +(1) and -(4) pins. The pulsating DC voltage is filtered and smoothed by the filter capacitor CX02 and then provided to the subsequent resonant heating circuit.

[0019] In the prior art, the filter inductor L1 is generally set at the output end of the + pin of the rectifier bridge stack of the rectifier filter circuit. However, when a lightning strike occurs, the high voltage current flows to the filter inductor L1, which is likely to have caused damage to the rectifier bridge stack. Therefore, the filter inductor L1 is pre-placed in the overcurrent, overvoltage and interference suppression circuit, and its own impedance is used together with the varistor RZ01 and the varistor RZ02 to significantly reduce the voltage, thereby avoiding damage to the rectifier bridge stack DB01.

[0020] The resonant heating circuit includes a wire coil, a resonant capacitor CXZ30, an IGBT30 and a TVS tube group. The resonant capacitor CXZ30 and the IGBT30 are connected in series between the two output terminals OUT1 and OUT2 of the rectifier and filter circuit. The wire coil is connected in parallel with the resonant capacitor CXZ30, and the TVS tube group is connected in parallel with the IGBT30. The TVS tube is a transient voltage suppression diode. When the two ends of the TVS tube are subjected to a momentary high-energy impact, it can suddenly reduce its impedance at a very high speed, while absorbing a large current, clamping the voltage between its two ends to a predetermined value, thereby ensuring that the subsequent circuit components are protected from damage by the transient high-energy impact. The lightning current may still have a higher voltage after being cut off by the overcurrent, overvoltage and interference suppression circuit and the rectifier and filter circuit to reach the resonant heating circuit. The use of the TVS tube group in parallel with the IGBT30 can directly shunt excessive current, thereby avoiding damage to the rectifier bridge DB01.

[0021] In this embodiment, the TVS tube group includes three TVS tubes, namely TVS1, TVS2 and TVS3. More TVS tubes may be used as needed.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lightning protection circuit for an electromagnetic heating device, comprising an overcurrent, overvoltage and interference suppression circuit, a rectifier filter circuit and a resonant heating circuit connected in sequence, characterized in that: An overcurrent, overvoltage and interference suppression circuit includes a fuse FS01, a varistor RZ01, a varistor RZ02, a filter capacitor CX01 and a filter inductor L1, wherein the AC-L of the alternating current is sequentially connected in series with the fuse FS01 and the varistor RZ01 to return to AC-N, the AC-L of the alternating current is serially connected with the filter inductor L01 and the varistor RZ02 to return to AC-N, the filter capacitor CX01 is connected in parallel with the varistor RZ02, and both ends of the filter capacitor CX01 are used as output ends of the overcurrent, overvoltage and interference suppression circuit for connecting the rectifier filter circuit; The resonant heating circuit includes a wire coil, a resonant capacitor CXZ30, an IGBT30 and a TVS tube group. The resonant capacitor CXZ30 and the IGBT30 are connected in series between two output terminals OUT1 and OUT2 of a rectifier and filter circuit. The wire coil is connected in parallel with the resonant capacitor CXZ30. The TVS tube group is connected in parallel with the IGBT30.

2. The lightning protection circuit of an electromagnetic heating device according to claim 1, characterized in that: The TVS tube group includes TVS1, TVS2 and TVS3.

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