A filtering capacitor energy transfer circuit and system

Abstract

The present application discloses a filter capacitor energy transfer circuit and system, relating to the field of circuit design. The energy transfer circuit includes a rectifier filter module, an AC waveform detection module, an auxiliary power supply module, an IGBT power tube, a control unit, and an energy transfer module, and the energy transfer module is respectively connected to the output end of the rectifier filter module, the output end of the control unit, and the input end of the auxiliary power supply module. When the circuit is in a low-power intermittent working state, the energy transfer module transfers the energy in the filter capacitor C1 to the auxiliary power supply module within a predetermined time period before the IGBT power tube is turned on according to the switch control signal SW1 output by the control unit, thereby effectively avoiding the instantaneous large current generated at the moment when the IGBT power tube is turned on, reducing the switching loss, and improving the safety and reliability of the system. In addition, by accurately controlling the energy transfer time by the control unit, a more uniform heating power output can be achieved, and the heating uniformity can be improved.

Description

Technical Field

[0001] The present invention relates to the field of circuit design, and more particularly to a filtering capacitor energy transfer circuit and system. Background Art

[0002] Electromagnetic heating devices are widely used in the field of household appliances. In the prior art, taking an induction cooker as an example, as Figure 1 shown, the electromagnetic heating device generally uses an LC resonance circuit for heating and reduces the switching loss of the insulated gate bipolar transistor (IGBT) through soft-switching technology. In the LC resonance circuit, when the IGBT is turned on, the resonance coil can effectively absorb energy; when the IGBT is turned off, most of the energy is transferred to the cookware for heating, and at the same time, part of the inertial energy is reversely charged to the resonance capacitor, causing the collector voltage of the IGBT to drop. When the heating power is large, the on-time of the IGBT is long and the current in the resonance coil is also large. In this case, its inertial energy can effectively reduce the collector voltage of the IGBT to nearly 0V, enabling the IGBT to be turned on again in the soft-switching state, thereby effectively reducing the switching loss.

[0003] However, when the heating power is small, the electromagnetic heating system enters the discontinuous operation mode. In the discontinuous mode, since the filtering capacitor stores the highest voltage after AC rectification during the dead zone, the voltage of the IGBT at the next turn-on is equal to the voltage of the filtering capacitor, resulting in a hard turn-on phenomenon. During the hard turn-on process, the current peak value at the moment when the IGBT is turned on is relatively high, easily exceeding the rated current of the IGBT, which is likely to cause device damage. In addition, the hard turn-on will also cause the problem of IGBT tube heating, and it is necessary to strengthen heat dissipation by means of increasing heat sinks, increasing the fan speed, etc., increasing the overall cost of the system. To avoid these problems, the switching frequency in the discontinuous mode is usually limited to below 0.2 Hz. However, this limitation will directly affect the heating uniformity, resulting in uneven heating when the electromagnetic heating device operates at low power. Summary of the Invention

[0004] The purpose of the present invention is to provide a filtering capacitor energy transfer circuit and system, which transfer the energy in the filtering capacitor to the auxiliary power supply module before the IGBT power tube is turned on in the low-power discontinuous working state, reduce the instantaneous large current and switching loss, and achieve uniform heating power adjustment.

[0005] To achieve the above purpose, the present invention discloses the following technical solutions:

[0006] In the first aspect of the present invention, a filtering capacitor energy transfer circuit is provided, including:

[0007] The rectifier and filter module is used to rectify and filter the input AC voltage and output the filtered voltage signal VB2 through the filter capacitor C1; the AC waveform detection module is used to detect the input AC voltage signal VA; the auxiliary power supply module is used to provide auxiliary operating voltage for each module in the circuit; the LC resonance module performs electromagnetic heating on the load based on the LC parallel resonance principle; the IGBT power tube is used to adjust the working state of the LC resonance module; the control unit controls the opening and closing of the IGBT power tube based on the AC voltage signal VA;

[0008] It also includes an energy transfer module, which is respectively connected to the output end of the rectifier and filter module, the output end of the control unit, and the input end of the auxiliary power supply module, and is used to transfer the energy in the filter capacitor C1 to the auxiliary power supply module according to the switch control signal SW1 output by the control unit within a predetermined period before the IGBT power tube is turned on when the circuit is in a low-power intermittent working state.

[0009] Optionally, in the above energy transfer circuit, the energy transfer module includes a third inductor L3, a third diode D3, a switch tube M1 and an energy storage capacitor C3;

[0010] One end of the third inductor L3 is connected to the voltage output end of the filter capacitor C1, and the other end is respectively connected to the anode end of the third diode D3 and the current input end of the switch tube M1; the cathode end of the third diode D3 is connected to one end of the energy storage capacitor C3 and connected to the input end of the auxiliary power supply module; the other end of the energy storage capacitor C3 is connected to the current output end of the switch tube M1 and is grounded; the control end of the switch tube M1 is connected to the output end of the control unit.

[0011] Furthermore, when the circuit is in a high-power continuous working state, the control unit outputs a low-level switch control signal SW1 to turn off the switch tube M1, and the auxiliary power module obtains the working voltage through the third inductor L3;

[0012] When the circuit is in a low-power discontinuous working state, the AC waveform detection module detects the AC voltage signal VA and its corresponding valley signal, and within a quarter of the AC cycle before the next turn-on signal after the dead zone of the IGBT power tube and before the valley of the AC voltage signal VA, the third inductor L3, the third diode D3, the switch tube M1 and the energy storage capacitor C3 form a boost circuit architecture, and the control unit outputs a PWM switch control signal SW1 to enable the switch tube M1 to enter a high-frequency switching working state, and transfer the energy in the filter capacitor C1 to the energy storage capacitor C3 through the third inductor L3 and the third diode D3.

[0013] Optionally, for the above energy transfer circuit, when the circuit is in a low-power intermittent working state, the control unit is further configured to adjust the on-frequency of the switching transistor M1, so that the energy transferred from the filter capacitor C1 to the energy storage capacitor C3 is consumed before the next switching cycle.

[0014] Optionally, the on-interval period of the switching transistor M1 is set to be greater than or equal to 5 periods of the AC voltage signal VA.

[0015] Optionally, for the above energy transfer circuit, the control unit includes a main control module and an IGBT driving module; the main control module is connected to the control end of the IGBT power transistor through the IGBT driving module, and controls the turning on and off of the IGBT power transistor through the first control signal PWM1.

[0016] Optionally, for the above energy transfer circuit, the main control module includes a comparator CMP and a logic AND gate And; the positive input terminal of the comparator CMP is connected to the filtered voltage signal VB2, the negative input terminal is connected to the superimposed signal of the AC voltage signal VA and the preset voltage signal Vx, and the output terminal is connected to one input terminal of the logic AND gate And; the other input terminal of the logic AND gate And is connected to the second control signal PWM2 output by the main control module, and a switch control signal SW1 is generated and output through the logic AND gate And to control the turning on and off of the switching transistor M1.

[0017] Further, the preset voltage signal Vx is a preset voltage difference between the filtered voltage signal VB2 and the AC voltage signal VA;

[0018] When the circuit is in a low-power intermittent working state, when the filtered voltage signal VB2 is higher than the AC voltage signal VA and the difference between them exceeds the preset voltage difference, the comparator CMP outputs a high-level signal, and the logic AND gate And outputs the same switch control signal SW1 as the second control signal PWM2, so that the switching transistor M1 enters a high-frequency switching state.

[0019] Optionally, for the above energy transfer circuit, a current sampling resistor is provided between the current output terminal of the switching transistor M1 and the ground terminal, which is used to collect the current signal of the switching transistor M1 and transmit the current signal to the main control module for feedback control of the switching transistor M1.

[0020] In the second aspect of the present invention, a filter capacitor energy transfer system is provided, which includes the filter capacitor energy transfer circuit as described in the first aspect, and further includes:

[0021] The EMI module is used to suppress electromagnetic interference in the grid input voltage and output the AC input voltage to the waveform sampling module and the rectification and filtering module;

[0022] The waveform sampling module is connected to the AC waveform detection module and is used to sample the waveform of the AC input voltage to generate an AC voltage signal VA;

[0023] The synchronization module is connected to the main control module and is used to control the IGBT power tube to turn on in the valley voltage state.

[0024] In the third aspect of the present invention, an electromagnetic heating device is provided, and the device includes the filter capacitor energy transfer system as described in the second aspect.

[0025] The effects provided in the summary of the invention are only the effects of the embodiments, rather than all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects:

[0026] A filter capacitor energy transfer circuit and system provided by the present application, the energy transfer circuit of which includes a rectification and filtering module, an AC waveform detection module, an auxiliary power supply module, an IGBT power tube, a control unit, and an energy transfer module. Through the collaborative work of each module unit, when the circuit is in a low-power intermittent working state, the energy transfer module transfers the energy in the filter capacitor to the auxiliary power supply module in a predetermined time period before the IGBT power tube is turned on according to the switch control signal output by the control unit, avoiding the instantaneous large current generated at the moment when the IGBT power tube conducts, effectively reducing the loss when the IGBT power tube switches, and improving the safety and reliability of the system. At the same time, this circuit can accurately control the energy transfer time through the control unit in the low-power intermittent mode, realize a more uniform heating power output, avoid power fluctuations during the heating process, and improve the heating uniformity and heating effect. [[ID=,16]] BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings here are incorporated into the specification and form a part of the specification, showing the embodiments in line with the present application, and are used together with the specification to explain the principles of the present application.

[0028] Figure 1 is the heating circuit schematic diagram of the induction cooker in the prior art;

[0029] Figure 2 is Figure 1 the schematic diagram of the voltage waveform of the filter capacitor C1 in

[0030] Figure 3 is the schematic diagram of the structure of a filter capacitor energy transfer circuit according to an embodiment of the present application;

[0031] Figure 4Schematic diagram of a filtering capacitor energy transfer circuit according to an embodiment of the present application;

[0032] Figure 5 is Figure 4 Schematic diagram of the voltage waveforms of the filtering capacitor C1 and the energy storage capacitor C3 in

[0033] Figure 6 is Figure 4 Schematic diagram of the control circuit of the main control module for the switching transistor M1 in

[0034] Figure 7 Schematic diagram of a filtering capacitor energy transfer system according to an embodiment of the present application. Detailed implementation manners

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] It should be noted that the references to "one embodiment", "embodiment", "example embodiment", etc. in this specification mean that the described embodiment may include specific features, structures or characteristics, but not every embodiment must include these specific features, structures or characteristics. In addition, such expressions do not refer to the same embodiment. Further, when combining an embodiment to describe a specific feature, structure or characteristic, whether or not there is an explicit description, it has been shown that it is within the knowledge of those skilled in the art to combine such features, structures or characteristics into other embodiments.

[0037] Referring to the background art and Figure 1 , in the prior art, taking an electromagnetic heating device such as an induction cooker as an example, its circuit structure includes a rectification and filtering module 110, an AC waveform detection module 120, an auxiliary power supply module 130, an LC resonance module 140, an IGBT power transistor 150, and a control unit 160. Among them, the AC waveform detection module 120 is used to detect the input AC voltage VA (i.e., the voltage at point A). The LC resonance module 140 is the main part of the induction cooker heating, and based on the principle of LC parallel resonance, it realizes the heating of the cookware through electromagnetic induction. Figure 2 is Figure 1 Schematic diagram of the voltage waveform of the filtering capacitor C1 in [[ID=�4]] Figure 2 , when the electromagnetic heating system works in a high-power or continuous mode, the voltage VB1 of the filtering capacitor C1 (i.e., the voltage at point B1) will fluctuate with the change of the load. In the case of a large load, since the capacitance of the filtering capacitor C1 is not sufficient to maintain the voltage stability, its voltage waveform will follow the voltage change after full-bridge rectification, as shown by the waveform in the 0-t1 period.

[0038] However, when the system operates in a low-power or intermittent mode, an intermittent working method is usually adopted, that is, it runs for a period of time and then stops for a period of time (referred to as the "dead time period"). The intermittent frequency in this working mode is generally less than 0.2 Hz, and as the power decreases, the duty cycle of the working cycle also decreases accordingly to achieve low-power operation. During the dead time period, since the load is almost zero, the filter capacitor C1 cannot discharge normally, so its voltage will remain at the highest voltage level after the input AC rectification. In the case of input AC 220V, the voltage of the filter capacitor C1 during the dead time period can remain at 310V, as Figure 2 shown by the waveform during the time period t1 - t2 in

[0039] Reference Figure 3 , Figure 3 shows a schematic structural diagram of a filter capacitor energy transfer circuit according to an embodiment of the present application. The circuit includes a rectifier filter module 210, which is used to rectify and filter the AC input voltage and supply it to the subsequent LC resonance module 240, and outputs a filtered voltage signal VB2 through the filter capacitor C1. An AC waveform detection module 220, which is used to detect the input AC voltage signal VA and its corresponding valley signal. An auxiliary power supply module 230, which is used to provide an auxiliary working voltage, such as 18V or 5V, etc., for each module in the circuit. An LC resonance module 240, which performs electromagnetic heating on the load based on the LC parallel resonance principle. An IGBT power transistor 250, which is used to adjust the working state of the LC resonance module 240. A control unit 260, which controls the on and off of the IGBT power transistor 250 based on the AC voltage signal VA. In addition, the circuit further includes an energy transfer module 270, which is respectively connected to the output end of the rectifier filter module 210, the output end of the control unit 260, and the input end of the auxiliary power supply module 230, and is used to transfer the energy in the filter capacitor C1 to the auxiliary power supply module 230 within a predetermined time period before the IGBT power transistor 250 is turned on when the circuit is in a low-power intermittent working state, according to the switch control signal SW1 output by the control unit 260.

[0040] In the circuit of this embodiment, the energy transfer module 270 can transfer the energy in the filter capacitor C1 to the auxiliary power supply module 230 within a predetermined time period before the IGBT power transistor 250 is turned on, effectively avoiding the instantaneous large current generated at the moment when the IGBT power transistor 250 conducts, reducing the loss when the IGBT power transistor 250 switches, and improving the efficiency and stability of the system. At the same time, by accurately controlling the energy transfer time through the control unit 260, the stable output of the heating power is ensured, the power fluctuation during the heating process is avoided, and the uniformity and heating effect of the load heating are improved.

[0041] Specifically refer to Figure 4 , Figure 4 which is a schematic diagram of a filter capacitor energy transfer circuit according to an embodiment of the present application. In this embodiment, the energy transfer module 270 includes a third inductor L3, a third diode D3, a switching transistor M1, and a storage capacitor C3. Among them, one end of the third inductor L3 is connected to the voltage output terminal of the filter capacitor C1, and the other end is respectively connected to the anode terminal of the third diode D3 and the current input terminal of the switching transistor M1. The cathode terminal of the third diode D3 is connected to one end of the storage capacitor C3 and is connected to the input terminal of the auxiliary power supply module 230. The other end of the storage capacitor C3 is connected to the current output terminal of the switching transistor M1 and is grounded. The control terminal of the switching transistor M1 is connected to the output terminal of the control unit 260. When the switching transistor M1 operates at high frequency switching, the third inductor L3, the third diode D3, the switching transistor M1, and the storage capacitor C3 form a boost circuit architecture to transfer the energy in the filter capacitor C1 to the auxiliary power supply module 230. In this circuit, when the circuit is in a high-power continuous working state, the control unit 260 outputs a low-level switching control signal SW1 to turn off the switching transistor M1, and the auxiliary power supply module 230 obtains the working voltage through the third inductor L3. When the circuit is in a low-power intermittent working state, the AC waveform detection module 220 detects the AC voltage signal VA and its corresponding valley signal, and within 1 / 4 of the AC cycle before the next turn-on signal after the dead time of the IGBT power transistor and before the valley of the AC voltage signal VA, the control unit 260 outputs a PWM switching control signal SW1 to turn on the switching transistor M1, and transfers the energy in the filter capacitor C1 to the storage capacitor C3 through the third inductor L3 and the third diode D3.

[0042] Figure 5 For Figure 4 is a schematic diagram of the voltage waveforms of the filter capacitor C1 and the storage capacitor C3 in Figure 5At time Ta, the voltage VB2 of the filtering capacitor C1 is slightly higher than the waveform of the AC voltage VA in synchronization, such that the voltage VB2 is greater than the voltage VA, thereby causing the rectification and filtering module 210 to cut off, and the voltage VB2 slowly decreases. When the IGBT power transistor 250 is turned on instantaneously, VB2 drops to nearly 0V. At this time, the starting current of the IGBT power transistor 250 slowly rises, effectively avoiding the generation of instantaneous large current.

[0043] In the discontinuous operation mode, the frequency of energy transfer needs to ensure that the auxiliary power supply module 230 can completely consume the energy transferred in the energy storage capacitor C3 to prevent the continuous accumulation of energy. If the transferred energy is not completely consumed, the grid energy cannot be supplemented through the third inductor L3. Only after the energy in the energy storage capacitor C3 is completely consumed can the grid energy be supplemented through the third inductor L3 to enter the normal working state. Specifically, the energy transferred from the filtering capacitor C1 to the energy storage capacitor C3 at one time is 1 / 2CU², where U is the input AC voltage and C is the capacitance value of the filtering capacitor C1. The average power P of the auxiliary power supply module 230 is a set value, usually between 3 - 5W, and its energy consumption is "P×T", where T is the energy consumption period. Therefore, to avoid the accumulation of electrical energy, it is necessary to ensure that the energy consumed by the auxiliary power supply module 230 in each energy consumption period T is greater than or equal to the energy transferred from the filtering capacitor C1 to the energy storage capacitor C3. According to the energy transfer relationship, the voltage of the energy storage capacitor C3 after energy transfer is times that of the initial voltage. Therefore, by adjusting the capacitance ratio of the filtering capacitor C1 and the energy storage capacitor C3, the voltage of the auxiliary power supply module 230 (i.e., the voltage at point D) can be effectively controlled to ensure that the circuit operates within a safe range.

[0044] For example, in an embodiment, when the AC voltage AC is 220V, the filtering capacitor C1 is 4.7uF, and the energy storage capacitor C3 is 10uF, the maximum voltage value of the energy storage capacitor C3 is (The loss of the auxiliary power supply module 230 itself during the conversion process is omitted here, and the actual voltage will be lower than this value). Assuming that the average power P of the auxiliary power supply module 230 is 3W, the energy transferred once is 1 / 2CU² = 0.5×4.7uF×310² = 0.225835J, then the time required for the auxiliary power supply module 230 to consume this energy is t = energy / average power = 0.225835 / 3 ≈ 75ms. Calculated according to the frequency of the AC voltage being 60Hz, each cycle is about 16.67 ms. Therefore, the time required to transfer energy once is equivalent to about 5 AC voltage cycles. That is to say, the opening interval period of the switching transistor M1 needs to be set to be greater than or equal to 5 AC voltage cycles to ensure that the energy in the filtering capacitor C1 can be completely consumed.

[0045] Based on the above analysis, in Figure 4In the embodiment, the control unit 260 includes a main control module, which can be used to adjust the switching frequency of the switching transistor M1 so that the energy transferred from the filter capacitor C1 to the energy storage capacitor C3 each time can be consumed before the next switching cycle. Refer to Figure 6 , Figure 6 is Figure 4 the schematic diagram of the control circuit of the main control module for the switching transistor M1. The main control module includes a comparator CMP and a logic AND gate And. Among them, the non-inverting input terminal of the comparator CMP is connected to the filter voltage signal VB2, the inverting input terminal is connected to the superimposed signal of the AC voltage signal VA and the preset voltage signal Vx, and the output terminal is connected to one input terminal of the logic AND gate And. The other input terminal of the logic AND gate And is connected to the second control signal PWM2 output by the main control module. The switching control signal SW1 is generated and output through the logic AND gate And, and the switching on and off of the switching transistor M1 is controlled by the switching control signal SW1.

[0046] In Figure 6 , the preset voltage signal Vx is a preset voltage difference between the filter voltage signal VB2 and the AC voltage signal VA, and this preset voltage difference determines the lowest valley voltage that point B2 can reach during the energy transfer cycle. When the circuit is in the low-power discontinuous operation state, when the filter voltage signal VB2 is higher than the AC voltage signal VA and the difference between the two exceeds this preset voltage difference, the comparator CMP outputs a high-level signal, and the logic AND gate And outputs the same switching control signal SW1 as the second control signal PWM2, so that the switching transistor M1 enters the high-frequency switching state.

[0047] For example, when Vx is set to 2V, in the dead zone state of the discontinuous mode, the voltage VB2 of the filter capacitor C1 is maintained at the highest value of about 310V. In the first quarter of the AC cycle when the IGBT power transistor 250 is turned on, the AC voltage VA shows a downward trend. When the voltage difference between VB2 and VA reaches 2V (that is, VB2 is 2V larger than VA), the comparator CMP outputs a high-level signal EN, and the circuit enters the energy transfer stage. At this time, the main control module outputs the second control signal PWM2, and the logic AND gate And then outputs the same switching control signal SW1 as the second control signal PWM2, and the switching transistor M1 enters the high-frequency switching state. As the switching transistor M1 is turned on, the energy transfer module 270 starts to work, transfers the energy in the filter capacitor C1 to the energy storage capacitor C3, and VB2 gradually decreases, thereby realizing the effective discharge of the voltage in the filter capacitor C1. By accurately controlling the switching time of the switching transistor M1 by the main control module, it is ensured that the energy transfer can be carried out during the optimal period, avoiding the occurrence of instantaneous large current and improving the operation stability of the circuit.

[0048] In Figure 4In the embodiment, the control unit 260 further includes an IGBT driving module. The main control module is connected to the control end of the IGBT power tube through the IGBT driving module, and controls the turning on and off of the IGBT power tube through the first control signal PWM1. In this embodiment, the switching tube M1 is taken as an example of an NMOS tube. Of course, in some other embodiments, the switching tube M1 can also use a triode or other types of switching tubes, which is not limited herein. In addition, in some embodiments, a current sampling resistor is further provided between the source electrode of the switching tube M1 and the ground, which is used to collect the current signal when the switching tube M1 works, and transmits the collected current signal to the main control module. Based on this current signal, the main control module precisely controls the switching tube M1 through the second control signal PWM to achieve the stable operation of the circuit.

[0049] In summary, for the filter capacitor energy transfer circuit of the embodiment of the present application, in the low-power intermittent working mode, the energy in the filter capacitor C1 is transferred to the energy storage capacitor C3 in advance, avoiding the instantaneous large current when the IGBT power tube is turned on, reducing the switching loss, and enhancing the safety and stability of the system. At the same time, the AC waveform detection module detects the waveform within a quarter of an AC cycle before the IGBT power tube is turned on to ensure the accuracy of the energy transfer process. In each quadrant cycle, the energy consumed by the auxiliary power supply module is greater than the energy transferred to the energy storage capacitor C3, preventing energy accumulation. In addition, by detecting the difference between the filter voltage VB2 and the AC voltage VA, when the difference between the two exceeds the preset voltage difference, the output switch signal SW1 controls the efficient operation of the switching tube M1, improving the accuracy and efficiency of the energy transfer and further improving the heating performance of the system.

[0050] It should be noted that Figure 4 The filter capacitor energy transfer circuit shown in the embodiment is only a preferred circuit structure for implementing the purpose of the present invention. In some other embodiments, each circuit module or device can also select other circuit structures that can achieve the same function, and the present application is not limited thereto.

[0051] Refer to Figure 7 , Figure 7This is a schematic diagram of a filtering capacitor energy transfer system according to an embodiment of the present application. The energy transfer system includes a filtering capacitor energy transfer circuit as described in the above embodiment, and further includes an EMI module 310, a waveform sampling module 320, and each functional module connected to the main control module. The EMI module 310 is used to suppress electromagnetic interference in the grid input voltage and output an AC input voltage to the waveform sampling module 320 and the rectification and filtering module 210. The waveform sampling module 320 is connected to the AC waveform detection module 220 and is used to sample the waveform of the AC input voltage to generate an AC voltage signal VA. The main control module is also connected to the synchronization module and is used to control the IGBT power transistor 250 to turn on in the valley voltage state to reduce switching losses and heat generation. The main control module is also connected to the current detection module and is used to detect the operating current of the system to adjust the power output in real time and provide overcurrent protection. The main control module is also connected to the protection module, the human-machine interaction module, and the cookware recognition module, which are respectively used to monitor the temperature and provide circuit protection, respond to user needs to adjust the working mode, and identify the cookware type to optimize the heating control. For the circuit structure and working process of the energy transfer system in this embodiment that are not described in detail, reference can be made to the relevant parts in the above energy transfer circuit embodiment and will not be elaborated here.

[0052] In addition, an embodiment of the present application further provides an electromagnetic heating device. The electromagnetic heating device includes a filtering capacitor energy transfer system as described in the above embodiment and is used to provide a uniform and stable heating power output for the load. For the circuit structure and working process of the electromagnetic heating device in this embodiment that are not described in detail, reference can be made to the relevant parts in the above energy transfer circuit embodiment and will not be elaborated here.

[0053] The above are only preferred embodiments of the present invention and are not intended to limit the present invention in any other form. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, as long as it does not depart from the technical solution content of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A filter capacitor energy transfer circuit, characterized in that Comprising: A rectification and filtering module, configured to rectify and filter the input AC voltage, and output a filtered voltage signal VB2 through a filtering capacitor C1; An AC waveform detection module, configured to detect the input AC voltage signal VA; an auxiliary power supply module, configured to provide an auxiliary operating voltage for each module in the circuit; an LC resonance module, based on the LC parallel resonance principle, for electromagnetic heating of the load; an IGBT power tube, configured to adjust the operating state of the LC resonance module; a control unit, based on the AC voltage signal VA, to control the turning on and off of the IGBT power tube; It further includes an energy transfer module, respectively connected to the output end of the rectification and filtering module, the output end of the control unit, and the input end of the auxiliary power supply module, and is configured to, when the circuit is in a low-power intermittent operating state, within a predetermined period before the IGBT power tube is turned on, according to the switch control signal SW1 output by the control unit, transfer the energy in the filtering capacitor C1 to the auxiliary power supply module; The energy transfer module includes a third inductor L3, a third diode D3, a switching tube M1, and a storage capacitor C3; One end of the third inductor L3 is connected to the voltage output end of the filtering capacitor C1, and the other end is respectively connected to the anodic end of the third diode D3 and the current input end of the switching tube M1; the cathodic end of the third diode D3 is connected to one end of the storage capacitor C3 and is connected to the input end of the auxiliary power supply module; the other end of the storage capacitor C3 is connected to the current output end of the switching tube M1 and is grounded; the control end of the switching tube M1 is connected to the output end of the control unit; When the circuit is in a high-power continuous operating state, the control unit outputs a low-level switch control signal SW1 to turn off the switching tube M1, and the auxiliary power supply module obtains the operating voltage through the third inductor L3; When the circuit is in a low-power intermittent operating state, the AC waveform detection module detects the AC voltage signal VA and its corresponding valley signal, and within 1 / 4 of the AC cycle before the valley of the AC voltage signal VA and before the next turn-on signal after the dead time of the IGBT power tube, the third inductor L3, the third diode D3, the switching tube M1, and the storage capacitor C3 form a boost circuit structure, and the control unit outputs a PWM switch control signal SW1 to make the switching tube M1 enter a high-frequency switching operating state, and transfer the energy in the filtering capacitor C1 to the storage capacitor C3 through the third inductor L3 and the third diode D3.

2. The filtering capacitor energy transfer circuit according to claim 1, wherein When the circuit is in a low-power intermittent operating state, the control unit is further configured to adjust the turn-on frequency of the switching tube M1, so that the energy transferred from the filtering capacitor C1 to the storage capacitor C3 each time is consumed before the next switching cycle.

3. The filter capacitor energy transfer circuit according to any one of claims 1-2, characterized in that, The control unit includes a main control module and an IGBT driving module; the main control module is connected to the control end of the IGBT power tube through the IGBT driving module, and controls the turn-on and off of the IGBT power tube through a first control signal PWM1.

4. The filter capacitor energy transfer circuit according to claim 3, wherein The main control module includes a comparator CMP and a logic AND gate And; the non-inverting input terminal of the comparator CMP is connected to the filtered voltage signal VB2, the inverting input terminal is connected to the superimposed signal of the AC voltage signal VA and the preset voltage signal Vx, and the output terminal is connected to one input terminal of the logic AND gate And; the other input terminal of the logic AND gate And is connected to the second control signal PWM2 output by the main control module, and a switch control signal SW1 is generated and output through the logic AND gate And to control the turning on and off of the switch tube M1.

5. The filter capacitor energy transfer circuit according to claim 4, wherein, The preset voltage signal Vx is a preset voltage difference between the filtered voltage signal VB2 and the AC voltage signal VA; When the circuit is in a low-power intermittent working state, when the filtered voltage signal VB2 is higher than the AC voltage signal VA and the difference between them exceeds the preset voltage difference, the comparator CMP outputs a high-level signal, and the logic AND gate And outputs the same switch control signal SW1 as the second control signal PWM2, causing the switch tube M1 to enter a high-frequency switching state.

6. The filter capacitor energy transfer circuit according to claim 5, wherein A current sampling resistor is arranged between the current output terminal of the switch tube M1 and the ground terminal, which is used to collect the current signal of the switch tube M1 and transmit the current signal to the main control module for feedback control of the switch tube M1.

7. A filtering capacitor energy transfer system, characterized in that, It includes the filter capacitor energy transfer circuit according to any one of claims 1 to 6, and further includes: An EMI module, which is used to suppress electromagnetic interference in the grid input voltage and output an AC input voltage to the waveform sampling module and the rectifier filter module; A waveform sampling module, which is connected to the AC waveform detection module and is used to sample the waveform of the AC input voltage to generate an AC voltage signal VA; A synchronization module, which is connected to the main control module and is used to control the IGBT power tube to turn on in the valley voltage state.

8. An electromagnetic heating device, characterized in that, It includes the filter capacitor energy transfer system according to claim 7.

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