A resonant control circuit and a heating device

Abstract

The application discloses a resonance control circuit and a heating device. The resonance control circuit comprises a resonance circuit, a state control unit and an energy storage circuit. The resonance circuit comprises a first inductor and a resonance capacitor connected in parallel. The state control unit is connected to a first end of the resonance circuit and is used for controlling the working state of the resonance circuit. The energy storage circuit is connected in parallel to both ends of the resonance circuit and is used for transferring part of the energy obtained by the first inductor through power charging. In the above manner, the application can reduce the loss of the state control unit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, in particular to a resonance control circuit and a heating device. BACKGROUND

[0002] At present, for cooking food by using electromagnetic induction, an electromagnetic heating circuit is usually adopted, and the electromagnetic heating circuit usually uses a single-pipe quasi-resonant topology. For the quasi-resonant topology, the coil current cannot be too large, and the larger the coil current is, the larger the resonant voltage is. If the current is too large, the voltage borne by the switch tube will also be higher, which will cause large loss of the switch tube. In addition, the coil current cannot be too small, and if the coil current is too small, the resonant capacitor voltage cannot be reset, and the switch tube cannot be turned on at zero voltage in the subsequent process, which will cause large loss of the switch tube. SUMMARY

[0003] The present application mainly solves the technical problem of providing a resonance control circuit and a heating device, which can reduce the loss of the state control element.

[0004] To solve the above technical problem, one technical solution adopted by the present application is to provide a resonance control circuit, which comprises a resonance circuit, a state control unit and an energy storage circuit. The resonance circuit comprises a first inductor and a resonant capacitor connected in parallel. The state control element is connected to the first end of the resonance circuit and is used to control the working state of the resonance circuit. The energy storage circuit is connected in parallel to the two ends of the resonance circuit and is used to transfer part of the energy obtained by the first inductor charged by the power supply.

[0005] The energy storage circuit comprises a storage element and a switching element connected in series. The switching element is used to disconnect the path between the power supply and the storage element during the charging process of the first inductor by the power supply, and to connect the path between the first inductor and the storage element during the discharging process of the first inductor after being charged by the power supply.

[0006] The second end of the resonance circuit is connected to the power supply. The switching element is specifically used to connect the path between the first inductor and the storage element in response to the voltage at the first end of the resonance circuit being greater than the voltage at the second end of the resonance circuit during the discharging process of the first inductor.

[0007] The switching element is a diode or a switch tube. The storage element is a second inductor.

[0008] The inductance values of the second inductor and the first inductor are the same. The second inductor is a heating coil.

[0009] The resonance control circuit further comprises at least one of the following: a filter circuit, one end of the filter circuit being connected to the second end of the resonance circuit and the other end of the filter circuit being grounded; and a power supply circuit, the second end of the resonance circuit being connected to the power supply circuit.

[0010] The filter circuit comprises a filter capacitor; the power supply circuit comprises a power supply and a rectifier circuit, an input end of the rectifier circuit is connected with the power supply, and an output end of the rectifier circuit is connected with the second end of the resonant circuit.

[0011] The power supply, the resonant circuit and the state control element form a loop, and the state control element is used for turning on the loop at the beginning of each cycle to charge the first inductor in the resonant circuit and turning off the loop after the beginning stage ends.

[0012] The state control element is a switch tube; and / or, the first inductor is a heating coil.

[0013] To solve the above technical problems, another technical solution adopted by the present application is to provide a heating device, which comprises a master control circuit and the resonant control circuit described above; wherein the master control circuit is used for controlling the state control element in the resonant control circuit to realize the control of the working state of the resonant circuit.

[0014] The above technical solution can transfer part of the energy obtained by charging the first inductor through the power supply, thereby reducing the energy transferred to the resonant capacitor, reducing the voltage peak value reached by the voltage at the first end of the resonant circuit, reducing the voltage borne by the state control element, reducing the voltage stress of the state control element, further reducing the loss of the state control element, and increasing the service life of the state control element; and since the voltage borne by the state control element is reduced, the requirement for the voltage resistance performance of the state control element is reduced, and since the state control element with low voltage resistance performance has a low cost, the cost can be reduced; in addition, compared with the resonant control circuit not additionally provided for transferring part of the energy of the first inductor, the corresponding heating power is greater when the voltage at the first end of the resonant circuit reaches the maximum peak value, therefore, the setting of the energy storage circuit can increase the upper limit of the heating power.

[0015] In addition, the part of the energy transferred to the energy storage circuit can be used as the charging energy in the recovery stage of the resonant capacitor, so that the voltage at the first end of the resonant circuit can also be reduced to zero voltage at a smaller heating power, on the one hand, the subsequent operation of the state control element in the zero voltage state can also be realized at a smaller heating power, and the lower limit of the heating power is lower; on the other hand, the loss of the state control element is reduced, and the service life of the state control element is increased. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of the resonant control circuit;

[0017] Figure 2 is Figure 1 is a waveform diagram of the signals in the resonant control circuit shown in FIG. 4;

[0018] Figure 3 is a structural schematic diagram of an embodiment of the resonance control circuit provided in the present application;

[0019] Figure 4 is a structural schematic diagram of another embodiment of the resonance control circuit provided in the present application;

[0020] Figure 5 is Figure 3 is a waveform diagram of signals in the resonance control circuit shown in

[0021] Figure 6 is a structural schematic diagram of an embodiment of the heating device provided in the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0023] It should be noted that if the description of "first", "second", etc. is involved in the embodiments of the present application, the description of "first", "second", etc. is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features with "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of the various embodiments can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present application.

[0024] Please refer to Figure 1 , Figure 1 is a structural schematic diagram of the resonance control circuit. The equivalent parameters of the inductor coil in the resonance circuit are equivalent inductance L1 and equivalent resistance R1. The inductor coil is periodically turned on and turned off through the switching tube Q1, so that the inductor coil is charged and oscillates in each period. That is, the electrical energy stored in the resonance capacitor C1 and the magnetic energy stored in the inductor coil are constantly converted to each other, so that a high-frequency varying magnetic field can be generated, and electromagnetic induction is used to heat food and the like.

[0025] Please refer to Figures 1-2 , Figure 2 is Figure 1 is a waveform diagram of signals in the resonance control circuit shown in Figure 2The solid waveform is shown in the diagram. At the beginning of each cycle, t0, the switch Q1 is turned on to charge the inductor, causing the current in the inductor to gradually increase until t1, when the switch Q1 is turned off. It should be noted that during the t0-t1 period, the voltage at the V_C terminal of the resonant capacitor C1 is 0V, and the left end of the resonant capacitor C1 corresponds to the voltage of the filter capacitor. After the switch Q1 is turned off, the current in the inductor begins to flow to the resonant capacitor C1, with the current direction from right to left. The voltage at the V_C terminal of the resonant capacitor C1 begins to rise until t2, when the current in the inductor drops to 0, meaning all the energy of the inductor is released. At this point, the voltage at the V_C terminal of the resonant capacitor C1 reaches its peak value. Starting at time t2, because the voltage across resonant capacitor C1 is simultaneously applied across the inductor, capacitor C1 begins to charge the inductor. At this time, the voltage at the V_C terminal of capacitor C1 begins to decrease, and the current in the inductor increases from right to left, opposite to the t0-t1 stage, and with a negative sign. At time t3, when the voltage at the V_C terminal of capacitor C1 decreases to the same level as the inductor's own voltage, the inductor current reaches its negative maximum value. At this point, the voltage at the V_C terminal of capacitor C1 is essentially the same as the voltage of the filter capacitor, meaning the voltage difference across capacitor C1 is essentially zero, and the energy stored in capacitor C1 is largely released. At time t4, the inductor current drops to 0, all the energy in the inductor is released, and the voltage at the V_C terminal of capacitor C1 also drops to 0V, meaning capacitor C1 recovers. Thus, one magnetic oscillation cycle ends.

[0026] Case 2 - The current in the inductor is relatively large, such as Figure 2 The waveform shown is a dotted line without points. When greater heating power is required, the conduction time of the switching transistor Q1 needs to be increased to increase the current in the inductor coil, thereby increasing the power. In this case, because the current in the inductor coil is larger, the inductor coil stores more energy, resulting in more energy being transferred to the resonant capacitor C1 during the t1-t2 stage. This leads to a larger voltage across the resonant capacitor C1, specifically a larger voltage at its V_C terminal. However, when the voltage at the V_C terminal of the resonant capacitor C1 is too high, the voltage across the switching transistor Q1 will also be too high, resulting in high voltage stress on the switching transistor Q1 and significant power loss.

[0027] Case 3 - The current in the inductor is relatively small, such as Figure 2The waveform is shown as a dotted line. When lower heating power is required, the on-time of the switching transistor Q1 needs to be shortened to reduce the current in the inductor coil, thereby reducing power. In this case, because the current in the inductor coil is smaller, less energy is transferred to the resonant capacitor C1 during the t1-t2 stage, and even less during the t2-t3 stage. This results in a smaller negative current peak in the inductor coil, meaning less stored energy. This may lead to insufficient energy for the recovery phase of the resonant capacitor C1, causing the current in the inductor coil to decrease to 0A before the voltage at the V_C terminal of the resonant capacitor C1 drops to 0V. Since the voltage at the V_C terminal of the resonant capacitor C1 cannot decrease further, zero-voltage turn-on cannot be achieved when the switching transistor Q1 is turned on at time t0 in the next cycle, resulting in significant losses in the switching transistor Q1.

[0028] To resolve the above issues, please refer to Figure 3 , Figure 3 This is a schematic diagram of an embodiment of the resonant control circuit provided in this application. The resonant control circuit 100 includes a resonant circuit 10, a state control element 20, and an energy storage circuit 30.

[0029] The resonant circuit 10 includes a first inductor (not shown in the figure) and a resonant capacitor C2 connected in parallel, forming a resonant circuit. When the resonant circuit 10 is powered by a power source, the first inductor is charged. After the power supply to the resonant circuit 10 is stopped for a period of time (i.e., after the power supply circuit is turned off), the first inductor discharges to charge the resonant capacitor C2. The voltage at the first terminal 11 of the resonant circuit 10, i.e., the voltage at the end of the resonant capacitor C2 closest to the state control element 20 (i.e., the voltage at the first terminal 11 of the resonant circuit 10), is the voltage at the end of the resonant capacitor C2 closest to the state control element 20. Figure 2 The voltage at the V_C terminal increases; after the resonant capacitor C2 finishes charging, it discharges. In other words, the resonant circuit 10 oscillates through the charging and discharging of the first inductor. The inductance value of the first inductor is not limited and can be set according to actual usage needs. Furthermore, it should be noted that the equivalent parameters of the first inductor are the equivalent inductance L2 and the equivalent resistance R2.

[0030] In one embodiment, the first inductor is a heating coil. When the first inductor is a heating coil, the resonant circuit 10 essentially involves the mutual conversion of the electric field energy of the resonant capacitor C2 and the magnetic field energy in the heating coil, with the total electric and magnetic field energy remaining constant at all times. In other words, the resonant circuit 10 converts the high-frequency alternating current into a high-frequency alternating magnetic field, generating eddy currents corresponding to the high-frequency alternating magnetic field. When these eddy currents flow on the surface of the heating coil, they make the electrons inside the metal very active, causing them to collide and rub against each other, thereby heating the conductor material inside the heating coil and thus heating food, etc.

[0031] The state control element 20 is connected to the first terminal 11 of the resonant circuit 10 and is used to control the operating state of the resonant circuit 10. In one specific embodiment, the power supply for charging the first inductor of the resonant circuit 10, the resonant circuit 10, and the state control element 20 form a loop. The state control element 20 is used to turn on the loop at the beginning of each cycle to enable the power supply to charge the first inductor in the resonant circuit 10, and to turn it off after the beginning of the cycle.

[0032] In one embodiment, the state control element 20 is a switching transistor Q2, which operates in the cutoff and saturation regions, effectively controlling the circuit's switching on and off states. In other words, when the state control element 20 is the switching transistor Q2, the operating state of the resonant circuit 10 is controlled by the switching transistor's on and off states. For example, ... Figure 3 As shown, the switch Q2, the power supply (not shown), and the resonant circuit 10 form a power supply loop for the resonant circuit 10. The switch Q2 is used to turn on the loop at the beginning of each cycle to charge the first inductor in the resonant circuit 10. After the beginning phase ends, i.e., after charging the first inductor of the resonant circuit 10, the switch Q2 turns off, and the first inductor of the resonant circuit 10 discharges to the resonant capacitor C2. Subsequently, the electrical energy stored in the resonant capacitor C2 and the magnetic energy stored in the first inductor continuously convert into each other, forming an oscillating discharge state. It is understood that in other embodiments, the state control element 20 can also be a diode or other components, which are not specifically limited here. The switch Q2 can be an N-MOS transistor, or it can be a relay, a thyristor, or an IGBT, or a P-MOS transistor.

[0033] The energy storage circuit 30 is connected in parallel to both ends of the resonant circuit 10, and is used to transfer part of the energy stored in the first inductor after charging by the power supply. After the power supply is used to supply power to the resonant circuit 10 for a period of time and then stopped, that is, after the power supply is turned off, the energy stored in the first inductor after charging by the power supply will be transferred to the resonant capacitor C2. At this time, the voltage at the first end 11 of the resonant circuit 10 gradually increases until all the energy stored in the first inductor after charging by the power supply is transferred to the resonant capacitor C2, at which time the voltage at the first end 11 of the resonant circuit 10 reaches a voltage peak. Therefore, when a larger heating power is required, the charging time of the power supply to the resonant circuit 10 is increased to increase the current of the first inductor, so that the first inductor stores more energy to achieve a larger power. However, when the first inductor stores more energy, more energy is subsequently transferred to the resonant capacitor C2, thereby causing the voltage at the first end 11 of the resonant circuit 10 to reach a larger voltage peak, which in turn causes the state control element 20 to bear a higher voltage, that is, the state control element 20 has high voltage stress, which can easily break down the state control element 20. Therefore, the state control element 20 has high voltage resistance performance requirements, but the cost of the state control element 20 with high voltage resistance performance is high. Therefore, by providing the energy storage circuit 30, part of the energy stored in the first inductor after charging by the power supply can be transferred, thereby reducing the energy transferred to the resonant capacitor C2, reducing the voltage at the first end 11 of the resonant circuit 10 to reach a voltage peak, thereby reducing the voltage borne by the state control element 20, that is, reducing the voltage stress of the state control element 20, thereby reducing the loss of the state control element 20 and increasing the service life of the state control element 20. Moreover, since the voltage borne by the state control element 20 is reduced, the voltage resistance performance requirement of the state control element 20 is reduced, and since the state control element 20 with low voltage resistance performance has a lower cost, the provision of the energy storage circuit 30 can reduce costs. In addition, since the energy storage circuit 30 can transfer part of the energy stored in the first inductor after charging, the heating power corresponding to the maximum peak voltage at the first end 11 of the resonant circuit 10 is larger than that without the resonant control circuit 100 for transferring part of the energy stored in the first inductor. Therefore, the provision of the energy storage circuit 30 can increase the upper limit of the heating power.

[0034] In addition, when a small heating power is required, the charging time of the power supply to the resonant circuit 10 is shortened, the current of the first inductor is reduced, and the first inductor stores less energy, so that a small power is obtained. After the energy obtained by the first inductor through the charging of the power supply is completely transferred to the resonant capacitor C2, the resonant capacitor C2 starts to charge the first inductor, that is, the energy of the resonant capacitor C2 starts to transfer to the first inductor. However, since a small heating power is required, the energy stored by the first inductor through the charging of the power supply is less, and the energy transferred to the resonant capacitor C2 is less, resulting in that the energy transferred from the resonant capacitor C2 to the first inductor is less, that is, the peak value of the negative current of the first inductor is smaller, and the energy stored by the first inductor is less. Since the energy stored by the first inductor is less, there may be insufficient energy to charge the resonant capacitor C2 in the subsequent recovery stage, so that the voltage at the first end 11 of the resonant circuit 10 cannot be reduced to 0V, the voltage stress of the state control element 20 cannot be reduced, and the state control element 20 cannot be controlled to operate in the zero voltage state in the subsequent stage. This will cause damage to the state control element 20. Therefore, by arranging the energy storage circuit 30, part of the energy obtained by the first inductor through the charging of the power supply can be transferred, and this part of energy can be used as the charging energy in the recovery stage of the resonant capacitor C2. Therefore, the voltage at the first end 11 of the resonant circuit 10 can be reduced to 0V even when a small heating power is required, on the one hand, the state control element 20 can be controlled to operate in the zero voltage state in the subsequent stage even when a small heating power is required, and the lower limit of the heating power is lower; on the other hand, the damage to the state control element 20 is reduced, and the service life of the state control element 20 is prolonged.

[0035] Please continue to refer to Figure 3 In an embodiment, the energy storage circuit 30 includes a series connection of an energy storage element (not shown in the figure) and a switching element 31. The switching element 31 is used to control the disconnection of the path between the power supply and the energy storage element during the charging of the first inductor by the power supply, and to control the conduction of the path between the first inductor and the energy storage element during the discharging of the first inductor after the charging by the power supply. That is, during the charging of the first inductor in the resonant circuit 10 by the power supply, the switching element 31 is in a disconnected state to control the disconnection of the path between the power supply and the energy storage element, so that the power supply uniquely charges the first inductor in the resonant circuit 10. When the charging of the first inductor in the resonant circuit 10 is stopped and enters the discharging process of the first inductor, the switching element 31 is in a working state to control the conduction of the path between the power supply and the energy storage element, so that the first inductor simultaneously transfers the energy obtained by the charging of the power supply to the resonant capacitor C2 and the energy storage element in the energy storage circuit 30, thereby realizing the transfer of part of the energy obtained by the first inductor through the charging of the power supply to the energy storage element.

[0036] For example, the energy storage circuit 30 includes a series connection of an energy storage element (not shown in the figure) and a switching element 31. Figure 3As shown, the switch element 31 can be a diode Dl. Specifically, the positive pole of the diode Dl is connected with the first end 11 of the resonant circuit 10, and the negative pole of the diode Dl is connected with the second end 12 of the resonant circuit 10. Alternatively, the diode Dl can be a rectifier diode or the like, which is not limited herein. It can be understood that in other embodiments, the switch element 31 can be a switch tube Q4, which is not limited herein. The switch tube Q4 can be an N-MOS tube, and can also be a relay, a thyristor, an IGBT or the like, or can be a P-MOS tube instead of the N-MOS tube. In addition, the energy storage element is a second inductor, and it should be noted that the equivalent parameters of the second inductor are an equivalent inductance L3 and an equivalent resistance R3. In an embodiment, the inductance values of the second inductor and the first inductor are the same. It can be understood that in other embodiments, the inductance values of the first inductor and the second inductor can also be different, which is not limited herein. In an embodiment, the second inductor is a heating coil. Figure 4 As shown, Figure 4 is a structural schematic diagram of another embodiment of the resonant control circuit provided by the present application. The switch element 31 can also be a switch tube Q4, which is not limited herein. The switch tube Q4 can be an N-MOS tube, and can also be a relay, a thyristor, an IGBT or the like instead of the N-MOS tube, or can be a P-MOS tube instead of the N-MOS tube. In addition, the energy storage element is a second inductor, and it should be noted that the equivalent parameters of the second inductor are an equivalent inductance L3 and an equivalent resistance R3. In an embodiment, the inductance values of the second inductor and the first inductor are the same. It can be understood that in other embodiments, the inductance values of the first inductor and the second inductor can also be different, which is not limited herein. In an embodiment, the second inductor is a heating coil.

[0037] In a specific embodiment, the second end 12 of the resonant circuit 10 is connected with a power supply, so the voltage of the second end 12 of the resonant circuit 10 is the voltage of the power supply, and since the voltage of the power supply is not affected by the working current of the first inductor, the voltage of the second end 12 of the resonant circuit 10 remains unchanged. The switch element 31 is specifically used to control the conduction of the path between the first inductor and the energy storage element in response to the voltage of the first end 11 of the resonant circuit 10 being greater than the voltage of the second end 12 of the resonant circuit 10 during the discharging process of the first inductor. That is, the switch element 31 conditionally controls the conduction of the path between the first inductor and the energy storage element. It can be understood that in other specific embodiments, the conduction of the path between the first inductor and the energy storage element can also be controlled under other conditions, which is not limited herein.

[0038] Specifically, as shown, Figure 3 , Figure 5 As shown, Figure 5 is Figure 3The waveform diagram of the signal in the shown resonance control circuit, the switch element 31 is a diode D1, the state control element 20 is a switch tube Q2, and the energy storage element is a second inductor. In the t0-t1 stage, the diode D1 is in an off state, the first inductor is charged by the power supply, and the current i-L2 of the first inductor gradually increases. Since the current i-L2 of the first inductor has been greater than 0A at the end of the last period, the current i-L2 of the first inductor starts charging from a value greater than 0A at the beginning of the current period. At t1, the charging of the first inductor by the power supply ends and the discharging process of the first inductor begins. Since the diode D1 controls the conduction between the first inductor and the second inductor when the voltage at the first end 11 of the resonance circuit 10 is greater than the voltage at the second end 12 of the resonance circuit 10, the first inductor begins to charge only the resonance capacitor C2, and the voltage at the first end 11 of the resonance circuit 10 begins to rise. As the voltage at the first end 11 of the resonance circuit 10 gradually rises, when the voltage at the first end 11 of the resonance circuit 10 rises to be greater than the voltage at the second end 12 of the resonance circuit 10, i.e., the power supply voltage, the diode D1 is in a conductive state to control the conduction between the first inductor and the second inductor. At this time, the current i-L2 of the first inductor begins to flow to the second inductor at the same time. In the t2-t3 stage, the current i-L2 of the first inductor flows to the second inductor and the resonance capacitor C2 at the same time. At t3, the current of the first inductor decreases to be the same as the current of the second inductor, and the charging of the resonance capacitor C2 by the first inductor ends at this time. At this time, there is still current in the first inductor, i.e., part of the energy of the first inductor has not been transferred to the resonance capacitor C2. Therefore, in the discharging process of the first inductor, the energy transferred from the first inductor to the resonance capacitor C2 is only part of the energy stored in the first inductor by the power supply. Compared with the mode in which all the energy stored in the first inductor by the power supply is transferred to the resonance capacitor C2, the voltage peak value reached by the voltage at the first end 11 of the resonance circuit 10 in the present application is reduced, thereby reducing the voltage borne by the switch tube Q2, i.e., reducing the voltage stress of the switch tube Q2, further reducing the loss of the switch tube Q2, and increasing the service life of the switch tube Q2. Moreover, since the voltage borne by the switch tube Q2 is reduced, the requirement for the voltage resistance performance of the switch tube Q2 is reduced. Since the switch tube Q2 with low voltage resistance performance has a low cost, the cost can be reduced by the arrangement of the energy storage circuit 30.In addition, since the second inductor can transfer part of the energy charged by the first inductor to reduce the voltage peak of the second end 12 of the resonant circuit 10, compared with the resonant circuit 10 without the energy storage circuit 30 for transferring part of the energy of the first inductor, the heating power corresponding to the maximum voltage stress that the switch tube Q2 can withstand when the voltage of the first end 11 of the resonant circuit 10 reaches the maximum peak is greater, and therefore, the setting of the energy storage circuit 30 can increase the upper limit of the heating power.

[0039] In the t3-t4 stage, the resonant capacitor C2 starts to charge the second inductor, and at the same time, the remaining current i-L2 in the first inductor continues to flow to the second inductor. At t4, the voltage of the first end 11 of the resonant circuit 10 and the voltage of the second end 12 of the resonant circuit 10 are substantially the same, that is, the voltage difference between the two ends is 0, at this time, the energy of the resonant capacitor C2 is completely transferred to the second inductor, and the current i-L2 of the first inductor reaches the minimum value. In the t4-t5 stage, the current of the second inductor starts to flow to the resonant capacitor C2 and the first inductor at the same time, the resonant capacitor C2 starts to recover, the voltage of the first end 11 of the resonant circuit 10 starts to decrease to 0V, and the current of the first inductor starts to increase. At t5, the voltage of the first end 11 of the resonant circuit 10 decreases to 0V. In the t4-t5 stage, the current of the second inductor flows to the resonant capacitor C2, that is, part of the energy of the first inductor charged by the power supply and transferred to the second inductor is used for the recovery stage of the resonant capacitor C2, so that the energy for the recovery of the resonant capacitor C2 is increased, on the one hand, the zero-voltage on-state switch tube Q2 can be realized at a smaller power, so that the lower limit of the heating power is lower; on the other hand, the loss of the switch tube Q2 is reduced, and the service life of the switch tube Q2 is increased.

[0040] In an embodiment, the resonant control circuit 100 further comprises at least one of a power supply circuit (not shown in the figure). The power supply circuit is connected to the second end 12 of the resonant circuit 10, and the power supply circuit is a power supply part of the circuit supply provided to the resonant control circuit 100, that is, the power supply circuit is the energy source of the resonant control circuit 100, and is used to power the resonant circuit 10 or other related circuits or components in the resonant control circuit 100, so as to maintain or ensure the normal operation of the resonant circuit 10 or other related circuits or components, thereby ensuring the normal operation of the resonant control circuit 100.

[0041] In one specific embodiment, the power supply circuit includes a power supply (not shown in the figure) and a rectifier circuit (not shown in the figure). The input terminal of the rectifier circuit is connected to the power supply, and the output terminal of the rectifier circuit is connected to the second terminal 12 of the resonant circuit 10. In one embodiment, the rectifier circuit is a full-bridge rectifier circuit, which includes a first diode, a second diode, a third diode, and a fourth diode. The cathode of the first diode is connected to the cathode of the third diode, and the anode of the first diode is connected to the cathode of the second diode and one end of the power supply. The cathode of the fourth diode is connected to the anode of the third diode and the other end of the power supply, and the anode of the fourth diode is connected to the anode of the second diode. The cathode of the third diode is connected to the second terminal 12 of the resonant circuit 10, and the anode of the fourth diode is connected to the state control element 20. The full-bridge rectifier circuit is used to convert the AC power output from the power supply into DC power by simultaneously turning on the first and fourth diodes and simultaneously turning off the second and third diodes, or by simultaneously turning off the first and fourth diodes and simultaneously turning on the second and third diodes. In other embodiments, the rectifier circuit may also be a half-bridge rectifier circuit or other circuits with the same function, which are not specifically limited here.

[0042] In one embodiment, the resonant control circuit 100 further includes a filter circuit 40. One end of the filter circuit 40 is connected to the second terminal 12 of the resonant circuit 10, and the other end of the filter circuit 40 is grounded. The filter circuit 40 is used to filter the direct current. It should be noted that when the resonant control circuit 100 does not include a power supply, the filter circuit 40 is directly connected to the mains power to filter the mains power, and the filtered direct current is used as the power source for the resonant control circuit 100.

[0043] In one specific implementation, such as Figure 3 As shown, the filter circuit 40 includes a filter capacitor, which is an energy storage device used to reduce the AC ripple coefficient and improve the efficiency and smoothness of DC output.

[0044] In one embodiment, the resonant control circuit 100 includes both a filter circuit 40 and a power supply circuit. The filter circuit 40 is connected to both ends of the power supply circuit, and one end of the filter circuit 40 is connected to the second end 12 of the resonant circuit 10, so that the filter circuit 40 can smooth the DC power output by the power supply circuit and supply the smoothed DC power to the resonant circuit 10 to power the resonant circuit 10.

[0045] Different from the prior art, the application provides a resonance control circuit, which comprises a resonance circuit, a state control unit and an energy storage circuit; the resonance circuit comprises a first inductor and a resonance capacitor connected in parallel; the state control element is connected to the first end of the resonance circuit and is used for controlling the working state of the resonance circuit; and the energy storage circuit is connected in parallel to the two ends of the resonance circuit and is used for transferring part of the energy obtained by the first inductor through power charging. By arranging the energy storage circuit, part of the energy obtained by the first inductor through power charging can be transferred, so that the energy transferred to the resonance capacitor is reduced, the voltage peak value reached by the voltage at the first end of the resonance circuit is reduced, the voltage borne by the state control element is reduced, that is, the voltage stress of the state control element is reduced, the loss of the state control element is further reduced, and the service life of the state control element is increased; and since the voltage borne by the state control element is reduced, the requirement for the voltage resistance performance of the state control element is reduced, and since the state control element with low voltage resistance performance has a low cost, the cost can be reduced; in addition, compared with the resonance control circuit without the energy storage circuit for transferring part of the energy of the first inductor, the corresponding heating power is greater when the voltage at the first end of the resonance circuit reaches the maximum peak value, and therefore, the arrangement of the energy storage circuit can increase the upper limit of the heating power.

[0046] In addition, the part of the energy transferred to the energy storage circuit can be used as the charging energy in the resonance capacitor recovery stage, so that the voltage at the first end of the resonance circuit can also be reduced to zero voltage at a smaller heating power, on the one hand, so that the state control element can also be controlled to operate at zero voltage in the subsequent state control element, and the lower limit of the heating power is lower; on the other hand, the loss of the state control element is reduced, and the service life of the state control element is increased.

[0047] Please refer to Figure 6 , Figure 6 is a structural schematic diagram of an embodiment of the heating device provided by the application. The application also provides a heating device 300, which comprises a master control circuit 200 and the resonance control circuit 100 in any of the above embodiments, wherein the master control circuit 200 is used for controlling the state control element 20 in the resonance control circuit 100, so as to control the working state of the resonance circuit 10.

[0048] The above description is only an embodiment of the application, and does not limit the patent scope of the application, and any equivalent structure or equivalent flow transformation obtained by using the content of the specification and the drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the application.

Claims

1. A resonant control circuit, characterized by, The resonant control circuit comprises: a resonant circuit comprising a first inductor and a resonant capacitor connected in parallel; a state control element connected to a first end of the resonant circuit for controlling the working state of the resonant circuit; a storage circuit connected in parallel to both ends of the resonant circuit for transferring part of the energy obtained by charging the first inductor by a power supply; the storage circuit comprises a storage element and a switching element connected in series, and a second end of the resonant circuit is connected to the power supply; the switching element is used to, in the discharging process after the first inductor is charged by the power supply, control the conduction of the path between the first inductor and the storage element in response to the voltage at the first end of the resonant circuit being greater than the voltage at the second end of the resonant circuit.

2. The resonance control circuit according to claim 1, characterized by, The switching element is also used to, in the process of charging the first inductor by the power supply, control the disconnection of the path between the power supply and the storage element.

3. The resonant control circuit of claim 1, wherein: the switching element is a diode or a switch tube; and / or the storage element is a second inductor.

4. The resonant control circuit of claim 3, wherein: the inductance value of the second inductor is the same as that of the first inductor; and / or the second inductor is a heating coil.

5. The resonance control circuit of claim 1, wherein, The resonant control circuit further comprises at least one of: a filter circuit, one end of which is connected to the second end of the resonant circuit and the other end of which is grounded; a power supply circuit, the second end of the resonant circuit being connected to the power supply circuit.

6. The resonance control circuit of claim 5, wherein, The filter circuit comprises a filter capacitor; the power supply circuit comprises a power supply and a rectifier circuit, the input end of the rectifier circuit being connected to the power supply and the output end of the rectifier circuit being connected to the second end of the resonant circuit.

7. The resonance control circuit of claim 1, wherein, The power supply, the resonant circuit and the state control element form a loop, and the state control element is used to conduct the loop at the beginning of each cycle to charge the first inductor in the resonant circuit by the power supply and to disconnect after the beginning stage ends.

8. The resonant control circuit of claim 1, wherein: the state control element is a switch tube; and / or the first inductor is a heating coil.

9. A heating device, characterized by The heating device comprises a master control circuit and a resonant control circuit as claimed in any one of claims 1-8; wherein the master control circuit is used to control the state control element in the resonant control circuit to control the working state of the resonant circuit.

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