Electromagnetic heating soft start circuit and electromagnetic heating equipment
By using the current limit control module in the electromagnetic heating device to reduce the driving voltage of the IGBT, the soft start effect of the IGBT is achieved, and the damage and noise problems caused by the high driving voltage of the IGBT in the prior art are solved, and the circuit cost and complexity are reduced.
Patent Information
- Application Number
- CN202323435047.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-14
- Publication Date
- 2025-02-14
- Estimated Expiration
- 2033-12-14
AI Technical Summary
The driving voltage of the existing electromagnetic heating equipment is high when starting, resulting in a large on-current, which increases the risk of IGBT damage and generates noise, affecting the user experience. At the same time, the existing solution requires adding a set of low-voltage driving power supplies, resulting in increased circuit costs and Implementation is complex.
The current limit control module controls the resistor access to reduce the driving voltage of the IGBT, so that the IGBT can achieve a soft start effect. Only one set of high-voltage driving power supplies are used to optimize the IGBT driving circuit structure.
Reduces the current and voltage peaks of IGBTs at startup, reduces IGBT losses, extends service life, and improves user experience by reducing noise, while reducing soft-start circuit costs and optimizing circuit structure.
Smart Images
Figure CN222484953U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of power electronics technology, and in particular to an electromagnetic heating soft start circuit and an electromagnetic heating device. Background Art
[0002] In the current market, electromagnetic heating products, such as induction cookers and induction rice cookers, typically use single-tube IGBT (insulated gate bipolar transistor) technology to control the resonant heating circuit. However, these devices often face the following problems when starting heating: the IGBT's C-pole voltage is non-zero, typically about 1.4 times the grid voltage. This results in a high IGBT on-state voltage and large instantaneous on-state current during the cooker detection (pot detection) or power startup phase, which increases IGBT losses. Especially under high grid voltage input, the instantaneous on-state current may exceed 150A, which not only increases the risk of IGBT damage but also generates a lot of noise (pot-smashing noise), affecting the user experience.
[0003] In the prior art, in order to solve the above problems, the general solution is to set up two sets of driving power supply circuits. During the pot detection or power startup stage, a lower driving voltage is first used to drive the IGBT. After the C-pole voltage of the IGBT is reduced, it is switched back to the normal driving voltage, thereby reducing the loss during the startup of the IGBT and reducing noise. However, this solution requires the addition of a set of low-voltage driving power supplies, which increases the circuit cost and makes the circuit implementation more complicated. Utility Model Content
[0004] The embodiments of the present application provide an electromagnetic heating soft start circuit and an electromagnetic heating device, which can at least solve the technical problems that the existing solution requires the addition of a set of low-voltage driving power supplies, resulting in increased circuit costs and more complex circuit implementation. Only one set of high-voltage driving power supplies can be used, and the resistor access can be controlled by a current limiting control module to reduce the driving voltage of the IGBT, so that the IGBT can achieve a soft start effect, thereby effectively reducing the cost of the soft start circuit and optimizing the circuit structure.
[0005] In a first aspect, an embodiment of the present application provides an electromagnetic heating soft start circuit, the electromagnetic heating soft start circuit comprising:
[0006] An electromagnetic heating module, comprising a coil disk and a resonant capacitor connected in parallel;
[0007] A zero-crossing detection module is connected to the AC power input terminal of the electromagnetic heating module;
[0008] An IGBT, a drain terminal of which is connected to the output terminal of the electromagnetic heating module and a source terminal of which is grounded;
[0009] A driving power supply is connected to the gate terminal of the IGBT via a first switching tube;
[0010] A current limiting control module includes a second switch tube, wherein a first current limiting resistor is provided between the input end and the output end of the second switch tube, and the input end and the output end are respectively connected to the input end and the control end of the first switch tube;
[0011] An MCU controller, wherein a first signal input end is connected to the output end of the zero-crossing detection module, a second signal input end is connected to both ends of the resonant capacitor, a first signal output end is connected to the control end of the second switch tube, and a second signal output end is connected to the control end of the first switch tube;
[0012] The MCU controller is configured to control the second switch tube to be turned off and the first switch tube to be turned on when receiving the zero-crossing signal sent by the zero-crossing detection module, so as to reduce the driving current of the IGBT.
[0013] In some embodiments, the MCU controller is further configured to control the second switch tube to turn on after the second switch tube is turned off.
[0014] In some embodiments, a second current-limiting resistor is provided between the output end of the second switching tube and the input end of the first switching tube, and the resistance of the second current-limiting resistor is smaller than the resistance of the first current-limiting resistor.
[0015] In some embodiments, the input end of the second current limiting resistor is connected to the output end of the first current limiting resistor, so that when the second switch tube is turned off, the first current limiting resistor and the second current limiting resistor are connected in series; when the second switch tube is turned on, the first current limiting resistor is short-circuited.
[0016] In some embodiments, the output end of the second current limiting resistor is connected to the output end of the first current limiting resistor, so that when the second switch tube is turned off, the second current limiting resistor branch is disconnected; when the second switch tube is turned on, the first current limiting resistor and the second current limiting resistor are connected in parallel.
[0017] In some embodiments, a third current-limiting resistor is provided between the driving power supply and the input end of the first switching tube, the resistance of the third current-limiting resistor is greater than the resistance of the second current-limiting resistor, and the input end and the output end of the second switching tube are respectively connected to the two ends of the third current-limiting resistor, so that when the second switching tube is turned off, the third current-limiting resistor is connected to the corresponding circuit of the driving power supply; when the second switching tube is turned on, the third current-limiting resistor is short-circuited.
[0018] In some embodiments, the output end of the first switch tube is grounded through the third switch tube, the control end of the first switch tube is connected to the control end of the third switch tube, and when the first switch tube is turned on, the third switch tube is turned off.
[0019] In some embodiments, the MCU controller includes a PPG module and an operational amplifier, the two input ends of the operational amplifier are respectively connected to the two ends of the resonant capacitor through two sets of voltage-dividing resistors, the output end of the operational amplifier is connected to the PPG module, and the PPG module is used to output a PPG signal through the second signal output end to turn on the first switch tube and turn off the third switch tube.
[0020] In some embodiments, the AC power input end of the electromagnetic heating module is further provided with a rectifier bridge.
[0021] In a second aspect, an embodiment of the present application provides an electromagnetic heating device, wherein the electromagnetic heating device is provided with the electromagnetic heating soft start circuit described in any one of the embodiments of the first aspect above.
[0022] The present application has at least the following beneficial effects: The present application proposes an electromagnetic heating soft start circuit, which is mainly used to solve the soft start problem in the IGBT drive circuit. By optimizing the IGBT drive circuit and adding a current limiting control module, when detecting a pot or starting the power, the second switch tube can be controlled to be turned off by the zero-crossing signal sent by the zero-crossing detection module, and the first switch tube can be turned on, so that the first current limiting resistor is connected to the circuit between the input end and the control end of the first switch tube to reduce the control end current of the first switch tube, so that the first switch tube can operate in an amplified state and cannot be saturated and turned on, so as to control the driving current flowing into the IGBT from the driving power supply to be reduced, and at the same time, the driving voltage of the IGBT is also reduced, so that the IGBT achieves a soft start effect, reduces the instantaneous current impact during pot detection and starting heating, and reduces the current and voltage peaks of the IGBT at startup, thereby reducing IGBT losses, extending service life, and improving the user experience by reducing noise at startup. Moreover, this design of controlling the driving voltage by connecting a resistor has lower cost and a simpler and more effective circuit structure than the existing two-set driving power supply circuit solution. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is a circuit diagram of an electromagnetic heating soft start circuit proposed in one embodiment of the present invention;
[0024] Figure 2 Another circuit diagram of the electromagnetic heating soft start circuit proposed in one embodiment of the present utility model;
[0025] Figure 3 Another circuit diagram of the electromagnetic heating soft start circuit proposed in one embodiment of the present utility model;
[0026] Figure 4This is a voltage waveform diagram of the electromagnetic heating soft start circuit proposed in one embodiment of the present utility model. DETAILED DESCRIPTION
[0027] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.
[0028] In some embodiments, although the system diagrams are divided into functional modules and the flow charts show a logical order, in some cases, the modules may be divided differently from those in the system. The terms "first," "second," and so on in the specification, claims, and drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence.
[0029] In addition, unless otherwise clearly specified and limited, the term "connection / connected" should be understood in a broad sense. For example, it can be a fixed connection or a movable connection, a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or able to communicate with each other; it can be a direct connection or an indirect connection through an intermediate medium.
[0030] In the description of the embodiments of the present application, the reference terms "one embodiment / implementation", "another embodiment / implementation" or "certain embodiments / implementations", "in the above-mentioned embodiments / implementations" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least two embodiments or implementations disclosed in the present application. In the disclosure of this application, the schematic representation of the above terms does not necessarily refer to the same exemplary embodiment or implementation. It should be noted that although a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in an order different from that in the flowchart.
[0031] In electromagnetic heating products currently on the market, such as induction cookers and induction rice cookers, conventional heating solutions typically use single-tube IGBT (insulated gate bipolar transistor) technology to control the resonant heating circuit. However, these devices often face the following problems when starting heating: the IGBT's C-pole voltage is non-zero, typically approximately 1.4 times the grid voltage. This results in a high IGBT on-state voltage and large instantaneous on-state current during the cookware detection (pot detection) or power startup phase, which leads to increased IGBT losses. In particular, under high grid voltage input, the instantaneous on-state current may exceed 150A, which not only increases the risk of IGBT damage but also generates loud noise (pot-smashing noise), affecting the user experience. In the prior art, to solve the above problems, a general solution is to set up two sets of drive power supply circuits. During the pot detection or power startup phase, a lower drive voltage is first used to drive the IGBT. After the IGBT's C-pole voltage drops, the normal drive voltage is switched back to, thereby reducing the IGBT startup losses and reducing noise. However, this solution requires the addition of a set of low-voltage drive power supplies, resulting in increased circuit cost and more complex circuit implementation.
[0032] The present application discloses an electromagnetic heating soft start circuit and an electromagnetic heating device, which can at least solve the technical problems that the existing solution requires the addition of a set of low-voltage drive power supplies, resulting in increased circuit costs and more complex circuit implementation. Only one set of high-voltage drive power supplies can be used, and the resistor access can be controlled by a current limiting control module to reduce the driving voltage of the IGBT, so that the IGBT can achieve a soft start effect, thereby effectively reducing the cost of the soft start circuit and optimizing the circuit structure.
[0033] The embodiments of the present application are further described below in conjunction with the accompanying drawings.
[0034] refer to Figure 1 , Figure 1This is a schematic diagram of an electromagnetic heating soft-start circuit proposed in an embodiment of the present application. In a first aspect, the embodiment of the present application provides an electromagnetic heating soft-start circuit, which includes: an electromagnetic heating module, including a coil disk and a resonant capacitor connected in parallel; a zero-crossing detection module, connected to the AC power input terminal of the electromagnetic heating module; an IGBT, with a drain terminal connected to the output terminal of the electromagnetic heating module and a source terminal grounded; a driving power supply, connected to the gate terminal of the IGBT through a first switching tube; a current limiting control module, including a second switching tube, a first current limiting resistor being provided between the input and output terminals of the second switching tube, and the input and output terminals being respectively connected to the input and control terminals of the first switching tube; an MCU controller, with a first signal input terminal connected to the output terminal of the zero-crossing detection module, a second signal input terminal connected to both ends of the resonant capacitor, a first signal output terminal connected to the control terminal of the second switching tube, and a second signal output terminal connected to the control terminal of the first switching tube; wherein the MCU controller is configured to control the second switching tube to be turned off and the first switching tube to be turned on upon receiving a zero-crossing signal sent by the zero-crossing detection module, so as to reduce the driving current of the IGBT.
[0035] Among them, the electromagnetic heating soft start circuit proposed in this application is mainly used to solve the soft start problem in the IGBT drive circuit. It optimizes the IGBT drive circuit and adds a current limiting control module. When detecting the pot or starting the power, the second switch tube can be controlled to turn off and the first switch tube can be turned on by receiving the zero-crossing signal sent by the zero-crossing detection module, so that the first current limiting resistor is connected to the circuit between the input end and the control end of the first switch tube to reduce the control end current of the first switch tube. The first switch tube can be operated in an amplified state and cannot be saturated and turned on to control the driving current flowing into the IGBT from the driving power supply. At the same time, the driving voltage of the IGBT is also reduced, so that the IGBT achieves a soft start effect, reduces the instantaneous current impact during pot detection and starting heating, and reduces the current and voltage peaks of the IGBT at startup, thereby reducing IGBT losses, extending service life, and improving the user experience by reducing noise at startup. Moreover, this design of controlling the driving voltage by connecting a resistor has lower cost and a simpler and more effective circuit structure than the existing two-set driving power supply circuit solution.
[0036] Specifically, refer to Figure 1 , Figure 1 Where Q1 is the first switch tube, Q4 is the second switch tube, R10 is the first current limiting resistor, MCU is the MCU controller, C2 is the resonant capacitor, L is the coil disk, IGBT1 is the above IGBT, and the drive power supply includes Figure 1 +18V AC power supply included Figure 1In the AC power supply, the two ends OUT1 and OUT2 of the resonant capacitor C2 are respectively connected to the two ends of the coil disk L. The resonant capacitor C2, the coil disk L and the IGBT can form an LC oscillation inverter circuit that serves as the working circuit of the induction cooker. The current can be oscillated between the coil disk L and the resonant capacitor C2 by turning on and off the IGBT, forming eddy current heating on the bottom of the iron pot. In contrast, the operational amplifier U1 and the PPG module in the MCU controller can form a synchronous detection circuit, which is used to detect the synchronization signal from both ends of the parallel circuit of the coil disk L and the resonant capacitor C2, and control the driving voltage of the gate terminal of the IGBT after shaping and amplification, so that the leading edge of the switching pulse voltage applied to the gate terminal of the IGBT is synchronized with the trailing edge of the peak voltage of the drain terminal, thereby realizing resonant current control and ensuring heating efficiency.
[0037] In some embodiments, a second current limiting resistor R8 is provided between the output end of the second switch tube Q4 and the input end of the first switch tube Q1 , and the resistance of the second current limiting resistor R8 is smaller than the resistance of the first current limiting resistor R10 .
[0038] In some embodiments, when the system of the present application needs to perform pot detection or start power, the drain terminal voltage of the IGBT is relatively high. At this time, according to the zero-crossing signal sent by the zero-crossing detection module, the second switch tube Q4 can be controlled to be in the off state through the IO port of the MCU before the grid crosses zero, and then the PPG module is started to output the PPG signal, so that the first switch tube Q1 of the IGBT drive circuit is turned on and the third switch tube Q5 is turned off. At this time, since the second switch tube Q4 is in the off state, the control end current of the first switch tube Q1 flows from 18V through the first current limiting resistor R10 and the second current limiting resistor R8. Since the resistance of the first current limiting resistor R10 is relatively large, the first switch tube Q1 operates in the amplification state and cannot be saturated and turned on, so as to control and reduce the drive current flowing into the IGBT, and at the same time reduce the drive voltage of the IGBT, so that the IGBT achieves a soft start effect.
[0039] In some embodiments, the MCU controller is also used to control the second switch tube Q4 to turn on after the second switch tube Q4 is turned off. It can be imagined that after the IGBT soft start is completed, the drain terminal voltage of the IGBT drops to zero. At this time, the second switch tube Q4 is controlled to turn on by the MCU, and the control terminal current of the first switch tube Q1 only passes through the second current limiting resistor R8 with a smaller resistance, so that the first switch tube Q1 reaches a saturated conduction state and drives the IGBT normally.
[0040] In some embodiments, the input end of the second current limiting resistor is connected to the output end of the first current limiting resistor, so that when the second switch tube is turned off, the first current limiting resistor and the second current limiting resistor are connected in series; when the second switch tube is turned on, the first current limiting resistor is short-circuited. It can be imagined that when detecting the pot or starting the power, when the second switch tube is turned off, the first current limiting resistor and the second current limiting resistor are connected in series, so that the first switch tube cannot be saturated and turned on, so as to control and reduce the driving current and driving voltage flowing into the IGBT, so that the IGBT achieves a soft start effect. After the IGBT soft start is completed, the second switch tube is turned on, and the first current limiting resistor is short-circuited, so that the first switch tube reaches a saturated conduction state and drives the IGBT normally.
[0041] In some embodiments, the MCU controller includes a PPG module and an operational amplifier. The two input terminals of the operational amplifier are connected to the two ends of the resonant capacitor through two sets of voltage-dividing resistors, and the output terminal of the operational amplifier is connected to the PPG module. The PPG module is used to output a PPG signal through the second signal output terminal to turn on the first switch tube and turn off the third switch tube. For details, refer to Figure 1 The two groups of voltage-dividing resistors include a first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a third voltage-dividing resistor R6 and a fourth voltage-dividing resistor R7, respectively. The positive input terminal of the operational amplifier U1 is connected to the output terminal of the resonant capacitor C2 through the second voltage-dividing resistor R2, and is grounded through the fourth voltage-dividing resistor R7. The reverse input terminal of the operational amplifier U1 is connected to the input terminal of the resonant capacitor C2 through the first voltage-dividing resistor R1, and is grounded through the third voltage-dividing resistor R6, thereby realizing the acquisition of the synchronization signal.
[0042] In some embodiments, the second signal output terminal of the MCU controller is an IO port, which is connected to the control terminal of the fifth switch tube Q3 through a first input resistor R5. The input terminal of the fifth switch tube Q3 is connected to the control terminal of the second switch tube Q4 through a second input resistor R4. The output terminal of the fifth switch tube Q3 is grounded to control the current of the control terminal of the second switch tube Q4. The second signal output terminal of the MCU controller is a PPG signal output port, which is connected to the control terminal of the fourth switch tube Q2 through a third input resistor R9. The input terminal of the fourth switch tube Q2 is connected to the control terminal of the first switch tube Q1. The output terminal of the fourth switch tube Q2 is grounded. The output terminal of the first switch tube Q1 is grounded through the third switch tube Q5. The control terminal of the first switch tube Q1 is connected to the control terminal of the third switch tube Q5. When the first switch tube is turned on, the third switch tube Q5 is turned off, so that the PPG module can output a PPG signal to control the driving voltage of the IGBT, thereby controlling the on and off of the first switch tube Q1.
[0043] In some embodiments, the output terminal of the first switch tube Q1 is connected to the gate terminal of the IGBT through the fourth input resistor R3.
[0044] In some embodiments, the first switch tube Q1, the second switch tube Q4, the third switch tube Q5, the fourth switch tube Q2 and the fifth switch tube Q3 are all NPN transistors, the input end is the collector of the NPN transistor, the input end is the emitter of the NPN transistor, and the control end is the base of the NPN transistor. The above-mentioned switch tubes can also be switching devices with controllable functions such as IGBTs, thyristors, and IEGT devices.
[0045] In some embodiments, the AC power input end of the electromagnetic heating module is further provided with a rectifier bridge.
[0046] In some embodiments, the AC power input terminal of the electromagnetic heating module is connected to the AC power supply, which includes an AC power supply. The two input terminals of the zero-crossing detection circuit are respectively connected to the two transmission lines of the AC power supply. The two input terminals of the rectifier bridge are also respectively connected to the two transmission lines of the AC power supply. One of the output terminals for outputting the rectified current is connected to the input terminal of the resonant capacitor, and the other output terminal is connected to the source terminal of the IGBT and is grounded.
[0047] In some embodiments, the input terminal of the resonant capacitor is connected to the source terminal of the IGBT through the filter capacitor C1 and is grounded.
[0048] refer to Figure 2 , Figure 2 Another circuit diagram of an electromagnetic heating soft-start circuit proposed in one embodiment of the present invention; in some embodiments, the output end of the second current-limiting resistor R8 is connected to the output end of the first current-limiting resistor R10, so that when the second switch tube Q4 is turned off, the second current-limiting resistor R8 branch is disconnected; when the second switch tube Q4 is turned on, the first current-limiting resistor R10 and the second current-limiting resistor R8 are connected in parallel. It can be imagined that when detecting the pot or starting the power, the second switch tube Q4 is turned off, the second current-limiting resistor R8 branch is disconnected, and the first current-limiting resistor R10 with a larger resistance is connected to the control end branch of the first switch tube Q1 to reduce the current at the control end of the first switch tube Q1, so that the first switch tube Q1 cannot be saturated and turned on, thereby controlling and reducing the drive current and drive voltage flowing into the IGBT, so that the IGBT achieves a soft-start effect. After the IGBT soft-start is completed, the second switch tube Q4 is turned on, and the first current-limiting resistor R10 and the second current-limiting resistor R8 are connected in parallel, so that the resistance of the control end branch of the first switch tube Q1 is reduced, and the first switch tube Q1 reaches a saturated and turned-on state, driving the IGBT normally.
[0049] refer to Figure 3 , Figure 3Another circuit diagram of the electromagnetic heating soft start circuit proposed in one embodiment of the present invention; in some embodiments, a third current limiting resistor R11 is provided between the driving power supply and the input end of the first switching tube, the resistance of the third current limiting resistor R11 is greater than the resistance of the second current limiting resistor R8, the input end and the output end of the second switching tube are respectively connected to the two ends of the third current limiting resistor, so that when the second switching tube is turned off, the third current limiting resistor R11 is connected to the corresponding circuit of the driving power supply; when the second switching tube is turned on, the third current limiting resistor R11 is short-circuited. It can be imagined that when detecting the pot or When the power is turned on, the second switch tube Q4 is turned off, and the third current-limiting resistor R11 is connected to the corresponding circuit of the driving power supply to reduce the current of the control terminal of the first switch tube Q1, so that the first switch tube Q1 cannot be saturated and turned on, thereby controlling and reducing the driving current and driving voltage flowing into the IGBT, so that the IGBT achieves a soft start effect. After the IGBT soft start is completed, the second switch tube Q4 is turned on and the third current-limiting resistor R11 is short-circuited, so that the resistance of the control terminal branch of the first switch tube Q1 is reduced, and the first switch tube Q1 reaches a saturated and turned-on state, and drives the IGBT normally.
[0050] refer to Figure 4 , Figure 4 This is a voltage waveform diagram of the electromagnetic heating soft start circuit proposed in one embodiment of the present utility model, wherein the upper part is the driving waveform of the IGBT, and the lower part is the drain terminal voltage waveform of the IGBT. It can be seen that the soft start of this application includes three stages, the first stage T1, the second stage T2 and the third stage T3. Specifically, in the initial state, the drain terminal voltage of the IGBT is the initial voltage U. In the first stage T1, after the zero-crossing detection module detects the zero-crossing point of the AC power, the MCU controller is used to control the second switch tube to turn off and the first switch tube to turn on when receiving the zero-crossing signal sent by the zero-crossing detection module, so as to reduce the drain terminal voltage waveform of the IGBT, reduce the driving current of the IGBT, and also reduce the driving voltage of the IGBT. At this time The driving voltage of the IGBT is V1. After the IGBT soft start is completed, the C-pole voltage of the IGBT drops to zero and enters the second stage T2. At this time, the second switch tube is controlled by the MCU to turn on and drive the IGBT normally. The drain terminal voltage of the IGBT begins to oscillate, triggering the resonant capacitor. At the same time, the driving voltage of the IGBT also increases to V2. V2 is the driving voltage of the IGBT normally. After heating is completed and the corresponding electromagnetic heating device is turned off, it enters the third stage T3. The driving voltage of the IGBT returns to zero, and the drain terminal voltage of the IGBT gradually recovers to the initial voltage U. Then it can enter the first stage T1, the second stage T2 and the third stage T3 again. The circuit of this application is repeated many times to make the IGBT achieve the soft start effect.
[0051] In a second aspect, an embodiment of the present application provides an electromagnetic heating device, in which an electromagnetic heating soft start circuit according to any one of the embodiments of the first aspect is provided.
[0052] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the above implementation mode. Technical personnel familiar with the field can also make various equivalent modifications or substitutions without violating the technical concept of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.
Claims
1. An electromagnetic heating soft start circuit, characterized in that: The electromagnetic heating soft start circuit comprises: An electromagnetic heating module, comprising a coil disk and a resonant capacitor connected in parallel; A zero-crossing detection module connected to an AC power input terminal of the electromagnetic heating module; IGBT, the drain terminal is connected to the output terminal of the electromagnetic heating module, and the source terminal is grounded; A driving power supply, connected to the gate terminal of the IGBT through a first switch tube; A current limiting control module, comprising a second switch tube, wherein a first current limiting resistor is arranged between an input end and an output end of the second switch tube, and the input end and the output end are respectively connected to an input end and a control end of the first switch tube; MCU controller, a first signal input end connected to the output end of the zero-crossing detection module, a second signal input end connected to the two ends of the resonant capacitor, a first signal output end connected to the control end of the second switch tube, and a second signal output end connected to the control end of the first switch tube; The MCU controller is used to control the second switch tube to turn off and the first switch tube to turn on when receiving the zero-crossing signal sent by the zero-crossing detection module, so as to reduce the driving current of the IGBT.
2. The electromagnetic heating soft start circuit according to claim 1, characterized in that: The MCU controller is further configured to control the second switch tube to turn on after the second switch tube is turned off.
3. The electromagnetic heating soft start circuit according to claim 1, characterized in that: A second current limiting resistor is provided between the output end of the second switch tube and the input end of the first switch tube, and the resistance value of the second current limiting resistor is smaller than the resistance value of the first current limiting resistor.
4. The electromagnetic heating soft start circuit according to claim 3, characterized in that: The input end of the second current limiting resistor is connected to the output end of the first current limiting resistor, so that when the second switch tube is turned off, the first current limiting resistor and the second current limiting resistor are connected in series; when the second switch tube is turned on, the first current limiting resistor is short-circuited.
5. The electromagnetic heating soft start circuit according to claim 3, characterized in that: The output end of the second current limiting resistor is connected to the output end of the first current limiting resistor, so that when the second switch tube is turned off, the second current limiting resistor branch is disconnected; when the second switch tube is turned on, the first current limiting resistor and the second current limiting resistor are connected in parallel.
6. The electromagnetic heating soft start circuit according to claim 3, characterized in that: A third current limiting resistor is arranged between the driving power supply and the input end of the first switching tube, the resistance of the third current limiting resistor is greater than the resistance of the second current limiting resistor, and the input end and the output end of the second switching tube are respectively connected to the two ends of the third current limiting resistor, so that when the second switching tube is turned off, the third current limiting resistor is connected to the corresponding circuit of the driving power supply; when the second switching tube is turned on, the third current limiting resistor is short-circuited.
7. The electromagnetic heating soft start circuit according to claim 1, characterized in that: The output end of the first switch tube is grounded through the third switch tube, the control end of the first switch tube is connected to the control end of the third switch tube, and when the first switch tube is turned on, the third switch tube is turned off.
8. The electromagnetic heating soft start circuit according to claim 7, characterized in that: The MCU controller includes a PPG module and an operational amplifier, the two input ends of the operational amplifier are respectively connected to the two ends of the resonant capacitor through two groups of voltage-dividing resistors, the output end of the operational amplifier is connected to the PPG module, and the PPG module is used to output a PPG signal through a second signal output end to turn on the first switch tube and turn off the third switch tube.
9. The electromagnetic heating soft start circuit according to claim 1, characterized in that: The AC power input end of the electromagnetic heating module is also provided with a rectifier bridge.
10. An electromagnetic heating device, characterized in that: The electromagnetic heating device is provided with an electromagnetic heating soft start circuit as described in any one of claims 1 to 9.