Electromagnetic heating system

Abstract

The utility model provides an electromagnetic heating system. The system comprises a filtering module, a rectification module, a current sampling module, an LC filtering module, an LC resonance circuit module, an IGBT switch tube, a zero-crossing signal generation module, a DC power supply voltage stabilization module, an MCU module and a display control module. According to the utility model, the power starting current can be reduced, and the instantaneous loss and electromagnetic noise of the switch tube can be reduced. During actual work, the zero-crossing signal generation module outputs a zero-crossing signal by detecting a zero-crossing point of an input alternating-current power supply, the MCU module outputs two discharge pulses directly generated by the MCU module to the IGBT switching tube at a falling edge of the zero-crossing signal, the LC resonant circuit module discharges, reduces IGBT-C pole voltage and then starts power, so that power starting current can be reduced, and power starting efficiency is improved. And the instantaneous loss and electromagnetic noise of the switching tube are reduced.

Description

Technical Field

[0001] The utility model relates to a heating system, in particular to an electromagnetic heating system. Background Art

[0002] In the prior art, the driving modes of electromagnetic heating systems mainly include the following three:

[0003] (1) Direct drive scheme, which uses 1 driving waveform and starts with pot detection. However, in the above driving mode, the starting voltage of IGBT-C is high and the current is large, so the IGBT is easily damaged.

[0004] (2) Step-down drive, such as the electromagnetic heating system and its starting control device and method for power switching tubes disclosed in the publication number CN110225608A, which adopts the IGBT-B step-down drive mode. However, the above driving mode has a complex hardware structure and high cost.

[0005] (3) Step-wave drive, such as the electromagnetic heating system and its control method and device disclosed in the publication number CN108024404A, which adopts the IGBT-B step-wave drive. However, in the above driving mode, the IGBT works in the amplification state, which does not meet the requirement that the IGBT works in the switching state, and there is a possibility of soft damage to the IGBT device, and the IGBT lacks quality assurance. Summary of the Utility Model

[0006] Aiming at the deficiencies of the prior art, the utility model provides an electromagnetic heating system and a control method, which can reduce the current of power startup, reduce the instantaneous loss and electromagnetic noise of the switching tube, and has a simple implementation method and low cost.

[0007] To achieve the above technical solution, the present utility model provides an electromagnetic heating system, comprising: a filtering module, a rectifying module, a current sampling module, an LC filtering module, an LC resonance circuit module, an IGBT switching tube, a zero-crossing signal generating module, a DC power supply voltage stabilizing module, an MCU module, and a display control module. Among them, the filtering module is connected to the input power supply, the rectifying module is installed behind the filtering module and connected to the filtering module, the current sampling module is installed behind the rectifying module and respectively connected to the rectifying module and the MCU module, the LC filtering module is installed behind the rectifying module and respectively connected to the rectifying module and the LC resonance circuit module, the LC resonance circuit module is installed between the LC filtering module and the IGBT switching tube, the IGBT switching tube is respectively connected to the LC resonance circuit module and the MCU module, the zero-crossing signal generating module is installed between the filtering module and the MCU module, the DC power supply voltage stabilizing module is installed between the filtering module and the MCU module, the MCU module is respectively connected to the current sampling module, the IGBT switching tube, the zero-crossing signal generating module, and the DC power supply voltage stabilizing module, the display control module is connected to the MCU module, and the display control module is used to complete operation display and send target power parameters to the power supply board.

[0008] Preferably, the LC filtering module is composed of an inductor L1 and a capacitor C1. Among them, one end of the inductor L1 is connected to the rectifying module, the other end of the inductor L1 is connected to the LC resonance circuit module, one end of the capacitor C1 is connected to the line where the inductor L1 is connected to the LC resonance circuit module, and the other end of the capacitor C1 is connected to the line where the current sampling module is connected to the IGBT switching tube.

[0009] Preferably, the LC resonance circuit module is composed of an inductor L2 and a capacitor C2. Among them, the inductor L2 is installed on the connection line between the LC filtering module and the IGBT switching tube, and the capacitor C2 is arranged in parallel with the inductor L2.

[0010] The beneficial effects of the electromagnetic heating system provided by the present utility model are as follows:

[0011] (1) The present utility model can reduce the current at power startup, reduce the instantaneous loss of the switching tube and electromagnetic noise. During actual operation, the zero-crossing signal generating module detects the zero-crossing point of the input AC power supply and outputs a zero-crossing signal. The MCU module outputs 2 discharge pulses directly generated by the MCU module to the IGBT switching tube at the falling edge of the zero-crossing signal, and the LC resonance circuit module discharges to reduce the IGBT-C pole voltage, and then starts the power, thereby being able to reduce the current at power startup, reduce the instantaneous loss of the switching tube and electromagnetic noise.

[0012] (2) In the initial stage of the power startup cycle, the MCU of the present utility model drives the IGBT-C to discharge with two narrow pulses at the zero-crossing position of the AC voltage according to the zero-crossing signal. The peak value of the discharge pulse is greater than or equal to 15V, which is the same as the peak value of the drive pulse, ensuring that the IGBT operates in the switching state. Moreover, the width of the discharge pulse can be adjusted according to the different distributed capacitances of the switching tubes to discharge the C pole of the switching tube, reducing the voltage of C. And the drive pulse is directly output from the IO port of the MCU without the need for peripheral hardware boost processing, with a simple implementation method and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the system structure diagram of the present utility model.

[0014] Figure 2 It is the drive pulse provided by the MCU module in the present utility model and the corresponding voltage diagram of the C pole of the IGBT switching tube.

[0015] In the figure: 1. Filter module; 2. Rectification module; 3. Current sampling module; 4. LC filter module; 5. LC resonance circuit module; 6. IGBT switching tube; 7. Zero-crossing signal generation module; 8. DC power supply voltage stabilization module; 9. MCU module; 10. Display control module. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0017] Embodiment: An electromagnetic heating system.

[0018] Refer to Figures 1 to 2 As shown, an electromagnetic heating system includes:

[0019] A filter module 1, the filter module 1 is connected to the input power supply, and the filter module 1 is used to prevent interference and improve EMC;

[0020] A rectification module 2, the rectification module 2 is installed behind the filter module 1 and connected to the filter module 1. The rectification module 2 is used to rectify the input positive AC voltage waveform and negative AC voltage waveform into a positive-polarity half-wave voltage waveform;

[0021] Current sampling module 3, the current sampling module 3 is installed behind the rectification module 2 and is respectively connected to the rectification module 2 and the MCU module 9. The current sampling module 3 is used to transmit the current parameter of the current working state of electromagnetic heating to the MCU module 9, compare it with the target current, and adjust the pulse width of the driving IGBT switch tube 6 to make the actual power current consistent with the target power current;

[0022] LC filtering module 4, the LC filtering module 4 is composed of an inductor L1 and a capacitor C1. Wherein, one end of the inductor L1 is connected to the rectification module 2, the other end of the inductor L1 is connected to the LC resonance circuit module 5, one end of the capacitor C1 is connected to the line where the inductor L1 is connected to the LC resonance circuit module 5, and the other end of the capacitor C1 is connected to the line where the current sampling module 3 is connected to the IGBT switch tube 6. The LC filtering module 4 is installed behind the rectification module 2 and is used to filter the positive half-wave voltage into a positive DC voltage;

[0023] LC resonance circuit module 5, the LC resonance circuit module 5 is installed between the LC filtering module 4 and the IGBT switch tube 6. The LC resonance circuit module 5 is composed of an inductor L2 and a capacitor C2. Wherein, the inductor L2 is installed on the connection line between the LC filtering module 4 and the IGBT switch tube 6, and the capacitor C2 is arranged in parallel with the inductor L2. The LC resonance circuit module 5 is used to generate a rapidly changing magnetic field. When the magnetic field lines of force pass through the metal cookware, eddy currents are generated in the metal cookware to achieve the heating effect;

[0024] IGBT switch tube 6, the IGBT switch tube 6 is respectively connected to the LC resonance circuit module 5 and the MCU module 9. The IGBT switch tube 6 is used to provide switching pulses to the resonance circuit. The MCU module 9 realizes power adjustment by adjusting the width of the switching pulses;

[0025] Zero-crossing signal generation module 7, the zero-crossing signal generation module 7 is installed between the filtering module 1 and the MCU module 9. The zero-crossing signal generation module 7 is used to provide discharge pulses to the MCU module 9 at the zero-crossing position of the AC voltage. The MCU module 9 outputs discharge pulses at the zero-crossing position to obtain the best discharge effect;

[0026] DC power supply voltage stabilization module 8, the DC power supply voltage stabilization module 8 is installed between the filtering module 1 and the MCU module 9. The DC power supply voltage stabilization module 8 is used to generate a VCC voltage of 15V - 18V to supply power to the MCU module 9;

[0027] The MCU module 9 is respectively connected to the current sampling module 3, the IGBT switching tube 6, the zero-crossing signal generating module 7, and the DC power supply voltage stabilizing module 8. The MCU module 9 is used for zero-crossing detection, current detection, voltage detection, power control, and outputs two narrow pulses at the zero-crossing position of the AC voltage to realize IGBT-C level discharge and reduce the starting voltage of the IGBT switching tube 6.

[0028] The display control module 10 is connected to the MCU module 9. The display control module 10 is used to complete operation display and send the target power parameter to the power supply board.

[0029] In the above technical solution, the current sampling module 3, the LC resonance circuit module 5, the IGBT switching tube 6, the zero-crossing signal generating module 7, and the MCU module 9 form a closed-loop power control system. The MCU module 9 calculates based on the sampled current of the current sampling module 3 and the target power current of the display control module 10, and outputs a pulse control signal to the IGBT switching tube 6. The IGBT switching tube 6 drives the LC resonance circuit module 5 to stabilize the resonance power within the target power range. When the MCU module 9 detects that the current sampling of the current sampling module 3 is 0, it outputs a new drive pulse to start a new power heating cycle.

[0030] In the above technical solution, during specific operation, the display control module 10 sends the target power to the MCU module 9, and the MCU module 9 converts the target power into a target current. The MCU module 9 outputs a start pulse at the zero point of the AC voltage according to the zero-crossing signal provided by the zero-crossing signal generating module 7 to drive the IGBT switching tube 6 to generate two discharge pulses and one normal pulse. The two discharge pulses in the present invention are directly generated by the MCU module 9. The amplitude of the first drive pulse is greater than or equal to 15V, and the width is between 0.5uS and 1.5uS. The parameters of the second drive pulse are the same as those of the first drive pulse. The C-pole voltage of the IGBT switching tube 6 has two step-downs, and normal power starts at the beginning of the second voltage step, which has the effect of reducing the IGBT-C power start current. After the power starts, the current sampling module 3 detects the current, and the MCU module 9 compares the current current with the target power current and outputs a modulation pulse to the IGBT switching tube 6. The IGBT switching tube 6 drives the LC resonance circuit module 5 to generate resonance power, thereby reducing the power start current, reducing the instantaneous loss of the switching tube and electromagnetic noise.

[0031] The above are the preferred embodiments of the present invention, but the present invention should not be limited to the embodiments and the content disclosed in the drawings. Therefore, all equivalent or modified implementations completed without departing from the spirit disclosed by the present invention fall within the protection scope of the present invention.

Claims

1. An electromagnetic heating system, characterized in that Including: a filtering module, a rectifying module, a current sampling module, an LC filtering module, an LC resonance circuit module, an IGBT switching tube, a zero-crossing signal generating module, a DC power supply voltage stabilizing module, an MCU module, and a display control module. Among them, the filtering module is connected to the input power supply. The rectifying module is installed behind the filtering module and connected to the filtering module. The current sampling module is installed behind the rectifying module and respectively connected to the rectifying module and the MCU module. The LC filtering module is installed behind the rectifying module and respectively connected to the rectifying module and the LC resonance circuit module. The LC resonance circuit module is installed between the LC filtering module and the IGBT switching tube. The IGBT switching tube is respectively connected to the LC resonance circuit module and the MCU module. The zero-crossing signal generating module is installed between the filtering module and the MCU module. The DC power supply voltage stabilizing module is installed between the filtering module and the MCU module. The MCU module is respectively connected to the current sampling module, the IGBT switching tube, the zero-crossing signal generating module, and the DC power supply voltage stabilizing module. The display control module is connected to the MCU module.

2. The electromagnetic heating system according to claim 1, characterized in that, The LC filtering module is composed of an inductor L1 and a capacitor C1. Among them, one end of the inductor L1 is connected to the rectifying module, and the other end of the inductor L1 is connected to the LC resonance circuit module. One end of the capacitor C1 is connected to the line where the inductor L1 is connected to the LC resonance circuit module, and the other end of the capacitor C1 is connected to the line where the current sampling module is connected to the IGBT switching tube.

3. The electromagnetic heating system according to claim 2, wherein, The LC resonance circuit module is composed of an inductor L2 and a capacitor C2. Among them, the inductor L2 is installed on the connection line between the LC filtering module and the IGBT switching tube, and the capacitor C2 is arranged in parallel with the inductor L2.

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