CN212677400U

CN212677400U - Fixed-frequency electromagnetic induction heating circuit

Info

Publication number: CN212677400U
Application number: CN202021430605.1U
Authority: CN
Inventors: 陈新; 李鹏; 罗军; 山江林
Original assignee: Foshan Shunde Xinxun Electronic Technology Co ltd
Current assignee: Foshan Shunde Xinxun Electronic Technology Co ltd
Priority date: 2020-07-20
Filing date: 2020-07-20
Publication date: 2021-03-09
Anticipated expiration: 2030-07-20

Abstract

The utility model provides a fixed frequency electromagnetic induction heating circuit, which comprises a resonance capacitor C1, a coil panel L1, a main switch K1 and a fly-wheel diode D1; the resonant capacitor C1 is connected in parallel with the coil disc L1, one end of the resonant capacitor is connected with the voltage VIN output by the rectifying circuit, and the other end of the resonant capacitor is grounded through the main switch and the freewheeling diode D1 thereof; the circuit also comprises a clamping circuit, wherein the clamping circuit comprises an auxiliary switch K2 and a freewheeling diode D2 thereof, and a clamping capacitor C2; clamp capacitor C2> > resonant capacitor C1; the auxiliary switch K2 and its freewheeling diode D2 are connected in series with the clamping capacitor C2 and then connected in parallel across the resonant capacitor C1 and the coil disk L1. The utility model discloses simple structure has reduced switching device's voltage stress, has realized the function of fixed-frequency regulation output, is particularly suitable for the application of a plurality of heating units of single main control chip control.

Description

Fixed-frequency electromagnetic induction heating circuit

Technical Field

The utility model relates to an electromagnetic induction heating field, especially a decide electromagnetic induction heating circuit frequently.

Background

The electromagnetic heating technology is to heat the utensil by utilizing the principle that the electromagnetic induction produces the vortex, at present, has generally been used for electrical apparatus such as electromagnetism kitchen, electric rice cooker, and the majority adopts capacitance inductance parallel resonance circuit, for example electromagnetism kitchen chooses IGBT as a power tube for use, because the resonance circuit parameter is the application under mainly satisfying high-power state, and at high-power during operation, IGBT is in zero state of conducting, and the loss is very little.

The chinese invention patent publication No. CN10053423C discloses an electromagnetic induction heating circuit, which, as shown in fig. 1, includes a rectifier circuit DB0, a filter circuit composed of an inductor L2 and a capacitor C2, an inductor L1, a capacitor C1 parallel resonance circuit, and a power tube IGBT; the parallel resonant circuit is internally provided with a compensation inductor L3 which is always in a working state in series, and the compensation inductor L3 is formed by at least one turn of the coil passing through at least one annular magnetic conductor.

At present, the working frequency of common civil electromagnetic induction heating equipment is generally between 18K and 40K, and the working frequency is influenced by external conditions and cannot be fixed at a specific working frequency, so that a filter design needs to be carried out aiming at a wide frequency domain, the design difficulty and the cost of the filter are increased, and in addition, when a plurality of heating equipment are simultaneously heated in a small area, the phenomenon of whistling of a heated appliance is caused due to the fact that different frequencies generate interference. However, the current electromagnetic induction heating circuit does not take these situations into consideration, and cannot meet the needs of users.

SUMMERY OF THE UTILITY MODEL

The utility model discloses in to present electromagnetic induction heating equipment to handling above-mentioned listed condition, can not satisfy not enough of user's needs, provide a decide electromagnetic induction heating circuit frequently.

The utility model discloses realize that its technical purpose technical scheme is: a constant-frequency electromagnetic induction heating circuit comprises a resonant capacitor C1, a coil panel L1, a main switch K1 and a freewheeling diode D1; the resonant capacitor C1 is connected in parallel with the coil disc L1, one end of the resonant capacitor is connected with the voltage VIN output by the rectifying circuit, and the other end of the resonant capacitor is grounded through the main switch and the freewheeling diode D1 thereof; the circuit also comprises a clamping circuit, wherein the clamping circuit comprises an auxiliary switch K2 and a freewheeling diode D2 thereof, and a clamping capacitor C2; clamp capacitor C2> > resonant capacitor C1; the auxiliary switch K2 and its freewheeling diode D2 are connected in series with the clamping capacitor C2 and then connected in parallel across the resonant capacitor C1 and the coil disk L1.

Further, in the fixed-frequency electromagnetic induction heating circuit: the main switch K1 and the auxiliary switch K2 are IGBTs.

Further, in the fixed-frequency electromagnetic induction heating circuit: the auxiliary switch K2 is an MOS tube, and the two D-S poles of the MOS tube are respectively connected with the N-P pole of the diode D2.

Further, in the fixed-frequency electromagnetic induction heating circuit: the auxiliary switch K2 is a triode, and the C-E two poles of the triode are respectively connected with the N-P pole of the diode D2.

Further, in the fixed-frequency electromagnetic induction heating circuit: the clamping capacitor C2> > resonant capacitor C1.

The utility model discloses simple structure has reduced switching device's voltage stress, has realized the function of fixed-frequency regulation output, is particularly suitable for the application of a plurality of heating units of single main control chip control.

The present invention will be described in more detail with reference to the accompanying drawings and examples.

Drawings

Fig. 1 shows an electromagnetic induction heating circuit in the prior art.

Fig. 2 is a schematic diagram of the fixed-frequency electromagnetic induction heating circuit of the present invention.

Fig. 3 is a schematic diagram of a fixed-frequency electromagnetic induction heating circuit according to embodiment 2 of the present invention.

Fig. 4 is a schematic diagram of a fixed-frequency electromagnetic induction heating circuit according to embodiment 3 of the present invention.

Detailed Description

The present embodiment is a constant frequency electromagnetic induction heating circuit, as shown in fig. 2, like the current electromagnetic induction heating circuit, including a resonant capacitor C1, a coil panel L1, a main switch K1, and a freewheeling diode D1; the resonant capacitor C1 is connected in parallel with the coil disc L1, one end of the resonant capacitor is connected with the voltage VIN output by the rectifying circuit, and the other end of the resonant capacitor is grounded through the main switch and the freewheeling diode D1 thereof; the circuit is certainly the same as the current electromagnetic induction heating circuit, and also comprises peripheral circuits such as matched synchronous detection, work protection, drive control and the like. Different from the current common electromagnetic induction heating circuit, the fixed frequency in the embodiment further includes a clamping circuit, the clamping circuit includes an auxiliary switch K2 and a freewheeling diode D2 thereof, and a clamping capacitor C2; clamp capacitor C2> > resonant capacitor C1; the auxiliary switch K2 and its freewheeling diode D2 are connected in series with the clamping capacitor C2 and then connected in parallel across the resonant capacitor C1 and the coil disk L1. In practice, the main switch K1 and the auxiliary switch K2 are IGBTs as shown in fig. 2. In some cases, the auxiliary switch K2 is a MOS transistor, and the two terminals D _ S of the MOS transistor are respectively connected to the N-P terminals of the diode D2, as shown in fig. 3. In some cases, the auxiliary switch K2 may also be a transistor, and as shown in fig. 4, the E _ C pole of the transistor is connected to the P _ N pole of the diode D2.

The invention adds a clamping circuit, a clamping capacitor C2 and an auxiliary switch K2 on the basis of the original single-tube free resonance circuit, and when the main switch K1 utilizes a synchronous circuit to realize normal zero-voltage switching.

When K1 is closed, coil panel L1 resonates with resonant capacitor C1, POINT _ C voltage rises, when voltage exceeds VIN, diode D2 is conducted, at the moment, clamping capacitor C2 is charged through diode D2, because C2> C1, because of the absorption capacity of clamping capacitor C2, POINT _ C voltage can be clamped near K VIN, and K is generally 1.2-2 times, in practice, if no clamping circuit exists, K is 3-4 times, therefore, compared with a common single-tube free resonant circuit, the voltage stress of a switching device can be greatly reduced, switching loss is reduced, and working efficiency is improved.

When the voltage at POINT _ C is clamped at K Vin, the voltage across the auxiliary switch K2 is zero, the zero voltage of the auxiliary switch K2 is turned on, the coil panel L1 resonates with the clamping capacitor C2, and the voltage at POINT _ C slowly drops but is basically kept near K Vin because C2> C1.

When the auxiliary switch K2 is turned off, the coil panel L1 resonates with the resonant capacitor C1, the voltage at POINT _ C starts to drop rapidly, and the main switch K1 is turned on again at the zero POINT of the drop POINT, thereby completing a control cycle.

The input energy of the circuit is determined by the turn-on time of the main switch K1, and the fixed frequency work is realized by adjusting the turn-on time of the auxiliary switch K2 by utilizing the transient and steady state process of POINT _ C POINT voltage clamping at K Vin.

The on-time of K2 can be determined by the equation "designed resonance period t0 ═ main switch on-time t1+ K2 delay on-time t2+ charge-discharge time t 3". The fixed frequency operation of the circuit is realized.

Claims

1. A constant-frequency electromagnetic induction heating circuit comprises a resonant capacitor C1, a coil panel L1, a main switch K1 and a freewheeling diode D1; the resonant capacitor C1 is connected in parallel with the coil disc L1, one end of the resonant capacitor is connected with the voltage VIN output by the rectifying circuit, and the other end of the resonant capacitor is grounded through the main switch and the freewheeling diode D1 thereof; the method is characterized in that: the circuit also comprises a clamping circuit, wherein the clamping circuit comprises an auxiliary switch K2 and a freewheeling diode D2 thereof, and a clamping capacitor C2; the auxiliary switch K2 and its freewheeling diode D2 are connected in series with the clamping capacitor C2 and then connected in parallel across the resonant capacitor C1 and the coil disk L1.

2. The fixed-frequency electromagnetic induction heating circuit according to claim 1, characterized in that: the main switch K1 and the auxiliary switch K2 are IGBTs.

3. The fixed-frequency electromagnetic induction heating circuit according to claim 1, characterized in that: the auxiliary switch K2 is an MOS tube, and two D _ S poles of the MOS tube are respectively connected with the N-P pole of the diode D2.

4. The fixed-frequency electromagnetic induction heating circuit according to claim 1, characterized in that: the auxiliary switch K2 is a triode, and the C _ E pole of the triode is respectively connected with the N _ P pole of the diode D2.

5. The fixed frequency electromagnetic induction heating circuit according to claim 1, 2, 3 or 4, characterized in that: the clamping capacitor C2> > resonant capacitor C1.