CN107528289B - Electromagnetic heating system and protection device thereof - Google Patents
Electromagnetic heating system and protection device thereof Download PDFInfo
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- CN107528289B CN107528289B CN201610455122.9A CN201610455122A CN107528289B CN 107528289 B CN107528289 B CN 107528289B CN 201610455122 A CN201610455122 A CN 201610455122A CN 107528289 B CN107528289 B CN 107528289B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/10—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current additionally responsive to some other abnormal electrical conditions
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/22—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage of short duration, e.g. lightning
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
- H03K17/082—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit
Abstract
The invention discloses an electromagnetic heating system and a protection device thereof, wherein the device comprises: the forward voltage surge detection circuit outputs a forward voltage surge signal when detecting that the input voltage of the electromagnetic heating system is greater than a first preset voltage; the current surge detection circuit outputs a current surge signal when detecting that the working current of the switching tube is greater than a first preset current; the switching tube overvoltage detection circuit outputs a switching tube overvoltage signal when detecting that the collector voltage of the switching tube is greater than a second preset voltage; the trigger circuit outputs a trigger protection signal according to the forward voltage surge signal, the current surge signal and the switching tube overvoltage signal so as to drive the switching tube to be turned off through the driving circuit. The device not only can avoid the influence that forward voltage surge signal and electric current surge signal caused the system, can avoid the switch tube to puncture because of bearing too high back pressure moreover to, the drive circuit of direct action on the switch tube after the protection signal triggers, thereby improved the protection rate of system.
Description
Technical Field
The invention relates to the technical field of household appliances, in particular to a protection device of an electromagnetic heating system and the electromagnetic heating system with the protection device.
Background
Generally, when an electromagnetic heating system such as an induction cooker works, the electromagnetic heating system is very easily interfered by a voltage surge signal and a current surge signal in a power grid and a working system, and because the amplitude of a transient interference signal of a surge is large and the destructiveness is strong, components in the system are very easily damaged, so that the work failure of the induction cooker is caused, and the electromagnetic heating system has great potential safety hazard.
In the related art, all induction cookers are provided with surge protection mechanisms, but the forward unidirectional surge protection mechanism has certain disadvantages: when a negative voltage surge signal comes before a positive voltage surge signal, due to the fact that capacitance charging and discharging exist, the voltage surge signal detected by the controller is pulled down, if the time interval of the two voltage surge signals is short, triggering surge interruption can not be completely established, leakage protection is caused, energy is completely accumulated on the switch tube at the moment, and the risk of transient overvoltage breakdown exists in the switch tube.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a protection device for an electromagnetic heating system, which can not only prevent a forward voltage surge signal and a current surge signal from affecting the system, but also prevent a switching tube from being broken down due to an excessive back voltage, and the protection signal is triggered and then directly acts on a driving circuit of the switching tube, so as to improve the protection rate of the system, and further improve the anti-interference capability and reliability of the system.
Another object of the present invention is to provide an electromagnetic heating system.
In order to achieve the above object, an embodiment of an aspect of the present invention provides a protection device for an electromagnetic heating system, where the electromagnetic heating system includes a resonant circuit, a rectifying and filtering circuit for providing energy to the resonant circuit, and a driving circuit for driving a switching tube to be turned on or off, the resonant circuit is composed of a heating coil, a resonant capacitor, and the switching tube, and the protection device includes: the forward voltage surge detection circuit outputs a forward voltage surge signal when detecting that the input voltage of the electromagnetic heating system is greater than a first preset voltage; the current surge detection circuit outputs a current surge signal when detecting that the working current of the switching tube is greater than a first preset current; the switching tube overvoltage detection circuit is connected with a collector of the switching tube to output a switching tube overvoltage signal when the voltage of the collector of the switching tube is detected to be greater than a second preset voltage; the trigger circuit is provided with a first signal input end, a second signal input end, a third signal input end and a trigger output end, the first signal input end is connected with the output end of the forward voltage surge detection circuit, the second signal input end is connected with the current surge detection circuit, the third signal input end is connected with the switch tube overvoltage detection circuit, the trigger output end is connected with the driving circuit, and the trigger circuit outputs a trigger protection signal according to the forward voltage surge signal, the current surge signal and the switch tube overvoltage signal so as to drive the switch tube to be turned off through the driving circuit.
According to the protection device of the electromagnetic heating system, the forward voltage surge detection circuit outputs a forward voltage surge signal when detecting that the input voltage of the electromagnetic heating system is greater than a first preset voltage, the current surge detection circuit outputs a current surge signal when detecting that the working current of the switching tube is greater than the first preset current, the switching tube overvoltage detection circuit outputs a switching tube overvoltage signal when detecting that the collector voltage of the switching tube is greater than a second preset voltage, and the trigger circuit outputs a trigger protection signal according to the forward voltage surge signal, the current surge signal and the switching tube overvoltage signal so as to drive the switching tube to be turned off through the drive circuit, so that the influence of the forward voltage surge signal and the current surge signal on the system can be avoided, the switching tube can be prevented from being broken down due to the fact that the switching tube bears too high back voltage, and the protection signal directly acts on the drive circuit of the switching tube after being triggered, therefore, the protection rate of the system is improved, and the anti-interference capability and reliability of the system are further improved.
According to an embodiment of the present invention, an input terminal of the current surge detection circuit is connected to an emitter of the switching tube through a first resistor to detect an operating current of the switching tube.
Further, the first resistor is a constantan wire.
According to an embodiment of the present invention, the current surge detection circuit includes: the circuit comprises a first resistor, a second resistor and a third resistor which are connected in series, wherein one end of the second resistor is connected with one end of the first resistor, the other end of the second resistor is connected with one end of the third resistor, the other end of the third resistor is connected with a preset power supply, a first node is arranged between the other end of the second resistor and one end of the third resistor, and the first node is connected with the ground through a first capacitor; a first diode, an anode of the first diode being connected to the first node; and the negative input end of the first comparator is connected with the cathode of the first diode, the positive input end of the first comparator is connected with a first reference voltage, and the output end of the first comparator is connected with the second signal input end of the trigger circuit.
According to one embodiment of the invention, the rectification filter circuit comprises a rectifier bridge, an absorption capacitor, a choke coil and an energy storage capacitor, wherein a first input end and a second input end of the rectifier bridge are correspondingly connected with two ends of an alternating current mains supply, the absorption capacitor is connected in parallel between a first output end and a second output end of the rectifier bridge, one end of the choke coil is connected with the first output end of the rectifier bridge, the other end of the choke coil is connected with one end of the energy storage capacitor and is connected to the resonance capacitor and the heating coil which are connected in parallel, and the other end of the energy storage capacitor is connected with the second output end of the rectifier bridge.
Further, an input end of the forward voltage surge detection circuit is connected with a first output end of the rectifier bridge to detect an input voltage of the electromagnetic heating system.
Further, the forward voltage surge detection circuit includes: the rectifier bridge comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a second capacitor, wherein the first resistor, the second resistor, the third resistor, the fourth resistor, the fifth resistor and the sixth resistor are connected in series, one end of the fourth resistor is connected with a first output end of the rectifier bridge, the other end of the fourth resistor is connected with one end of the fifth resistor, the other end of the fifth resistor is connected with one end of the sixth resistor, the other end of the sixth resistor is grounded, the fifth resistor is connected with the second capacitor in parallel, the sixth resistor is connected with; a second diode having an anode connected to the second node; and the positive input end of the second comparator is connected with the cathode of the second diode, the negative input end of the second comparator is connected with a second reference voltage, and the output end of the second comparator is connected with the first signal input end of the trigger circuit.
According to an embodiment of the invention, the switch tube overvoltage detection circuit comprises: the switch comprises an eighth resistor and a ninth resistor which are connected in series, wherein one end of the eighth resistor is connected with a collector of the switch tube, the other end of the eighth resistor is connected with one end of the ninth resistor, the other end of the ninth resistor is grounded, a third node is arranged between the other end of the eighth resistor and one end of the ninth resistor, and the ninth resistor is connected with a fourth capacitor in parallel; and a positive input end of the third comparator is connected with the third node, a negative input end of the third comparator is connected with a third reference voltage, and an output end of the third comparator is connected with a third signal input end of the trigger circuit.
According to one embodiment of the invention, the trigger circuit is a three-input nor gate.
Further, the three-input nor gate includes: the first input end of the OR gate is connected with the forward voltage surge detection circuit, and the second input end of the OR gate is connected with the current surge detection circuit; a first input end of the NOR gate is connected with the switching tube overvoltage detection circuit, and a second input end of the NOR gate is connected with an output end of the NOR gate; and the cathode of the third diode is connected with the output end of the NOR gate, and the anode of the third diode is connected with the driving circuit.
According to an embodiment of the present invention, the driving circuit includes: a collector of the first NPN triode is connected with a preset power supply through a tenth resistor, a base of the first NPN triode is connected with the output end of the trigger circuit, and an emitter of the first NPN triode is connected with the base of the switching tube; the emitter of the first PNP triode is connected with the emitter of the first NPN triode, the base of the first PNP triode is connected with the base of the first NPN triode, and the collector of the first PNP triode is grounded after being connected with the emitter of the switching tube; a collector of the second NPN triode is connected to a base of the first NPN triode and one end of an eleventh resistor, respectively, and the other end of the eleventh resistor is connected to the preset power supply, and an emitter of the second NPN triode is grounded; the circuit comprises a twelfth resistor and a thirteenth resistor which are connected in series, wherein one end of the twelfth resistor is connected with a base electrode of the second NPN triode, the other end of the twelfth resistor is connected with one end of the thirteenth resistor, the other end of the thirteenth resistor is connected with the preset power supply, a fourth node is arranged between the other end of the twelfth resistor and one end of the thirteenth resistor, and the fourth node is connected with a controller.
In addition, the embodiment of the invention also provides an electromagnetic heating system, which comprises the protection device of the electromagnetic heating system.
According to the electromagnetic heating system, the protection device of the electromagnetic heating system can avoid the influence of a forward voltage surge signal and a current surge signal on the system, can avoid breakdown of the switching tube due to the fact that the switching tube bears overhigh back voltage, and can directly act on a driving circuit of the switching tube after the protection signal is triggered, so that the protection rate of the system is improved, and the anti-jamming capability and reliability of the system are improved.
Drawings
Fig. 1 is a schematic structural view of a protection device of an electromagnetic heating system according to an embodiment of the present invention.
Fig. 2 is a circuit diagram of a protection device of an electromagnetic heating system according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The protection device of an electromagnetic heating system and the electromagnetic heating system having the same proposed according to an embodiment of the present invention are described below with reference to the accompanying drawings.
Fig. 1 is a schematic structural view of a protection device of an electromagnetic heating system according to an embodiment of the present invention.
In an embodiment of the present invention, as shown in fig. 1, the electromagnetic heating system may include a resonant circuit composed of a heating coil L0, a resonant capacitor C0, and a switching tube Q, a rectifying-filtering circuit 10 that supplies power to the resonant circuit, and a driving circuit 20 that drives the switching tube Q on or off.
As shown in fig. 1, the protection device of the electromagnetic heating system includes: a forward voltage surge detection circuit 30, a current surge detection circuit 40, a switching tube overvoltage detection circuit 50, and a trigger circuit 60.
Wherein, the forward voltage surge detection circuit 30 outputs a forward voltage surge signal when detecting that the input voltage of the electromagnetic heating system is greater than a first preset voltage. The current surge detection circuit 40 outputs a current surge signal when detecting that the working current of the switching tube Q is greater than a first preset current. The switch tube overvoltage detection circuit 50 is connected to the collector of the switch tube Q to output a switch tube overvoltage signal when detecting that the collector voltage of the switch tube Q is greater than a second preset voltage. The trigger circuit 60 has a first signal input terminal IN1, a second signal input terminal IN2, a third signal input terminal IN3 and a trigger output terminal OUT, the first signal input terminal IN1 is connected to the output terminal of the forward voltage surge detection circuit 30, the second signal input terminal IN2 is connected to the current surge detection circuit 40, the third signal input terminal IN3 is connected to the switching tube overvoltage detection circuit 50, the trigger output terminal OUT is connected to the driving circuit 20, and the trigger circuit 60 outputs a trigger protection signal according to the forward voltage surge signal, the current surge signal and the switching tube overvoltage signal to drive the switching tube Q to turn off through the driving circuit 20. The first preset voltage, the first preset current and the second preset voltage can be calibrated according to actual conditions.
Specifically, during the operation of the electromagnetic heating system, the rectifying and filtering circuit 10 converts the ac mains supply into the dc power to supply the electric energy to the resonant circuit, and the controller outputs a driving signal, such as a PPG (programmable Pulse Generator) signal, to the driving circuit 20, so as to drive the switching tube Q to be turned on and off through the driving circuit 20, and convert the dc power output by the rectifying and filtering circuit 10 into the high-frequency ac power. Meanwhile, the input voltage of the electromagnetic heating system, the operating current of the switching tube Q (i.e., the peak current when the system operates), and the collector voltage of the switching tube Q (i.e., the voltage applied to the switching tube Q) are detected in real time by the forward voltage surge detection circuit 30, the current surge detection circuit 40, and the switching tube overvoltage detection circuit 50, respectively.
If the input voltage of the electromagnetic heating system is greater than the first preset voltage, or the working current of the switching tube Q is greater than the first preset current, or the collector voltage of the switching tube Q is greater than the second preset voltage, that is, when there is a danger of input voltage surge, sudden change of working current, or serious overvoltage of the switching tube Q, etc., the corresponding detection circuit will output a corresponding signal to the trigger circuit 60, then, the trigger circuit 60 outputs a trigger protection signal to directly act on the driving circuit 20 of the switching tube Q, so as to rapidly turn off the switching tube Q, thereby not only avoiding the influence of the forward voltage surge signal and the current surge signal on the system, but also can avoid the breakdown of the switch tube due to the over-high back pressure, and the protection signal is directly acted on the driving circuit of the switch tube after being triggered, therefore, the protection rate of the system is improved, and the anti-interference capability and reliability of the system are further improved.
According to an embodiment of the present invention, as shown in fig. 1 or fig. 2, an input terminal of the current surge detection circuit 40 is connected to an emitter terminal of the switching tube Q through a first resistor R1 to detect an operating current of the switching tube Q. The first resistor R1 may be a constantan wire.
Specifically, as shown in fig. 2, the current surge detection circuit 40 may include: the circuit comprises a second resistor R2, a third resistor R3, a first diode D1 and a first comparator U1, wherein the second resistor R2 and the third resistor R3 are connected in series, one end of a second resistor R2 is connected with one end of a first resistor R1, the other end of the second resistor R2 is connected with one end of a third resistor R3, the other end of the third resistor R3 is connected with a preset power supply VCC, a first node J1 is arranged between the other end of a second resistor R2 and one end of the third resistor R3, and the first node J1 is connected with the ground GND through a first capacitor C1. An anode of the first diode D1 is connected to the first node J1. The negative input terminal of the first comparator U1 is connected to the cathode of the first diode D1, the positive input terminal of the first comparator U1 is connected to the first reference voltage REF1, and the output terminal of the first comparator U1 is connected to the second signal input terminal IN2 of the flip-flop circuit 60.
Specifically, as shown in fig. 2, an input end of the current surge detection circuit 40 is connected to a left end of a constantan wire, the constantan wire is connected in series with a preset power VCC, a second resistor R2 and a third resistor R3 for serial voltage division, a divided voltage signal is input to a negative input end of a first comparator U1 through a first diode D1, and a positive input end of the first comparator U1 is an adjustable first reference voltage REF 1. When the current flows through the constantan wire, the voltage at the left end of the constantan wire is a negative value, the larger the flowing current is, the larger the negative amplitude is, so the lower the voltage at the first node J1 is, when the voltage is lower than the first reference voltage REF1, the first comparator U1 is triggered to overturn, the output of the first comparator U1 is changed from a low-level signal to a high-level signal, namely, the current surge detection circuit 40 outputs a current surge signal to the trigger circuit 60, then, the trigger circuit 60 outputs a trigger protection signal to the driving circuit 20, so that the switching tube Q is driven to be turned off through the driving circuit 20, and therefore the influence on the system caused by the sudden change of the current is effectively avoided.
According to an embodiment of the present invention, as shown in fig. 1 or fig. 2, the rectifying and filtering circuit 10 includes a rectifying bridge 11, an absorbing capacitor C5, a choke coil L1 and an energy storage capacitor C6, a first input end and a second input end of the rectifying bridge 11 are correspondingly connected to two ends (L and N) of the ac mains, the absorbing capacitor C5 is connected in parallel between a first output end and a second output end of the rectifying bridge 11, one end of the choke coil L1 is connected to the first output end of the rectifying bridge 11, the other end of the choke coil L1 is connected to one end of the energy storage capacitor C6 and is connected to the parallel resonant capacitor C0 and the heating coil L0, and the other end of the energy storage capacitor C6 is connected to the second output end of the rectifying bridge 11.
Specifically, the ac mains may pass through a front-end EMC (Electro Magnetic Compatibility) module, and then pass through the rectifier filter circuit 10 to perform rectification filtering to output a stable dc power to provide electric energy to the resonant circuit, where a choke coil L1 and an absorption capacitor C5 in the rectifier filter circuit 10 form a filter circuit, filter the pulsating dc power output by the rectifier bridge 11 to output a stable dc power, and the energy storage capacitor C6 provides resonant energy for the resonant circuit, where the value of the resonant energy may be 5 μ F.
Further, an input terminal of the forward voltage surge detection circuit 30 is connected to a first output terminal of the rectifier bridge 11 to detect an input voltage of the electromagnetic heating system.
As shown in fig. 2, the forward voltage surge detection circuit 30 may include: the circuit comprises a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a second diode D2 and a second comparator U2, wherein the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6 are connected in series. One end of a fourth resistor R4 is connected with the first output end of the rectifier bridge 11, the other end of the fourth resistor R4 is connected with one end of a fifth resistor R5, the other end of the fifth resistor R5 is connected with one end of a sixth resistor R6, the other end of the sixth resistor R6 is grounded GND, the fifth resistor R5 is connected with a second capacitor C2 in parallel, the sixth resistor R6 is connected with a seventh resistor R7 and a third capacitor C3 which are connected in series in parallel, and a second node J2 is arranged between the other end of the fifth resistor R5 and one end of the sixth resistor R6. An anode of the second diode D2 is connected to the second node J2. A positive input of the second comparator U2 is connected to the cathode of the second diode D2, a negative input of the second comparator U2 is connected to the second reference voltage REF2, and an output of the second comparator U2 is connected to the first signal input IN1 of the flip-flop circuit 60.
Specifically, as shown in fig. 2, the input signal of the forward voltage surge detection circuit 30 is a half-wave voltage signal obtained by rectifying the ac mains through the rectifier bridge 11, the voltage signal is divided by the fourth resistor R4, the fifth resistor R5 and the sixth resistor R6, the divided voltage signal is input to the positive input terminal of the second comparator U2 through the second diode D2, and the negative input terminal of the second comparator U2 is an adjustable second reference voltage REF 2. The second capacitor C2 may be a high voltage ceramic capacitor connected in parallel with the fifth resistor R5 to temporarily snap-operate in response to a voltage surge signal, thereby achieving an instantaneous short circuit. The seventh resistor R7 and the third capacitor C3 are connected in series and then connected in parallel with the sixth resistor R6 to filter the voltage surge signal, so that the sensitivity of the voltage surge signal is improved. The second comparator U2 can be a high-speed comparator, the second comparator U2 performs high-low level conversion according to the magnitude of the input voltage, for example, when a voltage surge occurs, the voltage at the second node J2 will be higher than the second reference voltage REF2, at this time, the second comparator U2 outputs a high-level signal, that is, the forward voltage surge detection circuit 30 outputs a voltage surge signal to the trigger circuit 60, then, the trigger circuit 60 outputs a trigger protection signal to the driving circuit 20, so as to drive the switching tube Q to turn off through the driving circuit 20, thereby effectively avoiding the influence on the system due to the input voltage surge.
According to an embodiment of the present invention, as shown in fig. 2, the switch tube overvoltage detection circuit 50 may include: the circuit comprises an eighth resistor R8, a ninth resistor R9 and a third comparator U3, wherein the eighth resistor R8 and the ninth resistor R9 are connected in series. One end of the eighth resistor R8 is connected with the collector of the switching tube Q, the other end of the eighth resistor R8 is connected with one end of the ninth resistor R9, the other end of the ninth resistor R9 is grounded GND, a third node J3 is arranged between the other end of the eighth resistor R8 and one end of the ninth resistor R9, and the ninth resistor R9 is connected with a fourth capacitor C4 in parallel. A positive input of the third comparator U3 is connected to the third node J3, a negative input of the third comparator U3 is connected to a third reference voltage REF3, and an output of the third comparator U3 is connected to the third signal input IN3 of the flip-flop circuit 60.
Specifically, as shown in fig. 2, the input signal of the switching tube overvoltage detection circuit 50 is a voltage signal of the collector of the switching tube Q, and is also a voltage signal on the right side of the resonant capacitor C0. The voltage signal is divided by the eighth resistor R8 and the ninth resistor R9, the divided voltage signal is directly inputted to the positive input terminal of the third comparator U3, and the negative input terminal of the third comparator U3 is the adjustable third reference voltage REF 3. When the over-voltage of the switching tube Q is serious, the voltage at the third node J3 exceeds the set third reference voltage REF3, the third comparator U3 outputs a high level signal, that is, the switching tube over-voltage detection circuit 50 outputs a switching tube over-voltage signal to the trigger circuit 60, then the trigger circuit 60 outputs a trigger protection signal to the driving circuit 20 to drive the switching tube Q to be turned off through the driving circuit 20, thereby realizing the over-voltage interruption protection of the switching tube, effectively solving the problem of leakage protection caused by the fact that a negative voltage surge signal is earlier than a positive voltage surge signal and the time interval between the two surge signals is too small in the related art, and performing the second protection on the switching tube.
According to one embodiment of the present invention, the trigger circuit 60 may be a three-input NOR gate.
Specifically, as shown in fig. 2, the three-input nor gate may include: an OR gate OR, a NOR gate NOR and a third diode D3, wherein a first input terminal of the OR gate OR is connected to the forward voltage surge detection circuit 30, a second input terminal of the OR gate OR is connected to the current surge detection circuit 40, a first input terminal of the NOR gate NOR is connected to the switching tube overvoltage detection circuit 50, a second input terminal of the NOR gate NOR is connected to an output terminal of the OR gate OR, a cathode of the third diode D3 is connected to an output terminal of the NOR gate NOR, and an anode of the third diode D3 is connected to the driving circuit 20.
Specifically, as shown in fig. 2, the input terminals of the OR gate OR are connected to the output terminal of the forward voltage surge detection circuit 30 and the output terminal of the current surge detection circuit 40, respectively, and when any input signal of the OR gate OR is a high level signal, the OR gate OR outputs the high level signal. The NOR gate NOR can be an open-drain output NOR gate, the input ends of which are respectively connected with the output end of the OR gate OR and the output end of the switch tube overvoltage detection circuit 50, when any input signal of the NOR gate NOR is a high-level signal, the NOR gate NOR outputs a low-level signal and directly acts on the drive circuit 20 of the switch tube; otherwise, the output voltage signal is determined by the external circuit. That is, the three-input nor gate may be divided into two stages, the first stage being an OR gate, and the input terminals of the OR gate are the forward voltage surge detection circuit 30 and the current surge detection circuit 40, both of which share the same priority; the second level is the first level output end and the switch tube overvoltage detection circuit 50, so that the switch tube overvoltage detection circuit 50 can enjoy higher priority, not only plays a role in leakage protection of forward voltage surge signals, but also plays a role in second protection.
Further, as shown in fig. 2, the driving circuit 20 may include: a first NPN transistor NPN1, a first PNP transistor PNP1, a second NPN transistor NPN2, a twelfth resistor R12, and a thirteenth resistor R13, wherein a collector of the first NPN transistor NPN1 is connected to the preset power source VCC through a tenth resistor R10, a base of the first NPN transistor NPN1 is connected to the output terminal of the trigger circuit 60, an emitter of the first NPN transistor NPN1 is connected to a base of the switching tube Q, an emitter of the first NPN transistor PNP1 is connected to an emitter of the first NPN transistor NPN1, a base of the first NPN transistor PNP1 is connected to a base of the first NPN transistor NPN1, a collector of the first NPN transistor PNP1 is connected to the emitter of the switching tube Q and then grounded GND, a collector of the second NPN transistor 2 is connected to a base of the first NPN transistor 1 and one end of the eleventh resistor R11, the other end of the eleventh resistor R11 is connected to the preset power source VCC, and an emitter of the second NPN2 is grounded, the twelfth resistor R12 and the thirteenth resistor R13 are connected in series, one end R12 of the twelfth resistor is connected with the base of the second NPN transistor NPN2, the other end of the twelfth resistor R12 is connected with one end of the thirteenth resistor R13, the other end of the thirteenth resistor R13 is connected with the preset power source VCC, a fourth node J4 is arranged between the other end of the twelfth resistor R12 and one end of the thirteenth resistor R13, and the fourth node J4 is connected with the controller.
Specifically, as shown in fig. 2, the PPG signal output by the controller is inverted by the second NPN transistor NPN2, and then applied to the base stage of the switching tube Q after passing through the push-pull circuit formed by the first NPN transistor NPN1 and the first PNP transistor PNP 1. The input of the push-pull circuit is also connected to the output of the three-input nor gate via a third diode D3. When overvoltage does not occur, the output end of the three-input NOR gate is open-drain output, and the input end of the push-pull circuit is a signal of a PPG signal acting on the second NPN triode NPN2 to provide a driving signal for normal operation for a switching tube Q in the resonant circuit; when overvoltage occurs, the output end of the three-input NOR gate is a low level signal, the input end of the push-pull circuit is instantly pulled to the low level signal through the third diode D3, the base signal of the switching tube Q is pulled down at the moment, the switching tube Q is closed, and power output is stopped, so that protection of the switching tube is realized.
That is, in the embodiment of the present invention, the input voltage of the electromagnetic heating system, the peak current of the system during operation, and the voltage applied to the switching tube Q can be detected in real time by the forward voltage surge detection circuit 30, the current surge detection circuit 40, and the switching tube overvoltage detection circuit 50, respectively. When the potential dangers such as input surge voltage, current mutation, serious overvoltage of the switching tube and the like are detected, if the potential dangers reach the triggering threshold values of the respective comparators, the comparators output high-level signals, the triggering circuit 60 outputs triggering protection signals and directly acts on the driving circuit 20 of the switching tube Q to quickly close the switching tube Q, and therefore protection of the switching tube is achieved.
According to the protection device of the electromagnetic heating system, the forward voltage surge detection circuit outputs a forward voltage surge signal when detecting that the input voltage of the electromagnetic heating system is greater than a first preset voltage, the current surge detection circuit outputs a current surge signal when detecting that the working current of the switching tube is greater than the first preset current, the switching tube overvoltage detection circuit outputs a switching tube overvoltage signal when detecting that the collector voltage of the switching tube is greater than a second preset voltage, the trigger circuit outputs a trigger protection signal according to the forward voltage surge signal, the current surge signal and the switching tube overvoltage signal so as to drive the switching tube to be turned off through the drive circuit, thereby not only avoiding the influence of the forward voltage surge signal and the current surge signal on the system, but also avoiding the switching tube from being broken down due to the over-high back voltage, and directly acting on the drive circuit of the switching tube after the trigger of the protection signal, therefore, the protection rate of the system is improved, and the anti-interference capability and reliability of the system are further improved.
In addition, the embodiment of the invention also provides an electromagnetic heating system, which comprises the protection device of the electromagnetic heating system, wherein the electromagnetic heating system can be an electromagnetic oven, an electric cooker and the like.
According to the electromagnetic heating system, the protection device of the electromagnetic heating system can avoid the influence of a forward voltage surge signal and a current surge signal on the system, can avoid breakdown of the switching tube due to over-high back pressure, and can directly act on a driving circuit of the switching tube after the protection signal is triggered, so that the protection rate of the system is improved, and the anti-jamming capability and reliability of the system are improved.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A protection device of an electromagnetic heating system is characterized in that the electromagnetic heating system comprises a resonance circuit, a rectifying and filtering circuit for providing energy for the resonance circuit and a driving circuit for driving a switching tube to be switched on or switched off, the resonance circuit is composed of a heating coil, a resonance capacitor and the switching tube, and the protection device comprises:
the forward voltage surge detection circuit outputs a forward voltage surge signal when detecting that the input voltage of the electromagnetic heating system is greater than a first preset voltage;
the current surge detection circuit outputs a current surge signal when detecting that the working current of the switching tube is greater than a first preset current;
the switching tube overvoltage detection circuit is connected with a collector of the switching tube to output a switching tube overvoltage signal when the voltage of the collector of the switching tube is detected to be greater than a second preset voltage;
the trigger circuit is provided with a first signal input end, a second signal input end, a third signal input end and a trigger output end, the first signal input end is connected with the output end of the forward voltage surge detection circuit, the second signal input end is connected with the current surge detection circuit, the third signal input end is connected with the switch tube overvoltage detection circuit, the trigger output end is connected with the driving circuit, and the trigger circuit outputs a trigger protection signal according to the forward voltage surge signal, the current surge signal and the switch tube overvoltage signal so as to drive the switch tube to be turned off through the driving circuit;
wherein the trigger circuit is a three-input nor gate, the three-input nor gate comprising:
the first input end of the OR gate is connected with the forward voltage surge detection circuit, and the second input end of the OR gate is connected with the current surge detection circuit;
a first input end of the NOR gate is connected with the switching tube overvoltage detection circuit, and a second input end of the NOR gate is connected with an output end of the NOR gate;
and the cathode of the third diode is connected with the output end of the NOR gate, and the anode of the third diode is connected with the driving circuit.
2. A protection device for an electromagnetic heating system according to claim 1, wherein an input terminal of the current surge detection circuit is connected to an emitter terminal of the switching tube through a first resistor to detect an operating current of the switching tube.
3. A protection device for an electromagnetic heating system according to claim 2, characterized in that said first electrical resistance is a constantan wire.
4. A protection arrangement for an electromagnetic heating system according to claim 2, characterized in that the current surge detection circuit comprises:
the circuit comprises a first resistor, a second resistor and a third resistor which are connected in series, wherein one end of the second resistor is connected with one end of the first resistor, the other end of the second resistor is connected with one end of the third resistor, the other end of the third resistor is connected with a preset power supply, a first node is arranged between the other end of the second resistor and one end of the third resistor, and the first node is connected with the ground through a first capacitor;
a first diode, an anode of the first diode being connected to the first node;
and the negative input end of the first comparator is connected with the cathode of the first diode, the positive input end of the first comparator is connected with a first reference voltage, and the output end of the first comparator is connected with the second signal input end of the trigger circuit.
5. The protection device of the electromagnetic heating system according to claim 1, wherein the rectifying and filtering circuit comprises a rectifying bridge, an absorption capacitor, a choke coil and an energy storage capacitor, a first input end and a second input end of the rectifying bridge are correspondingly connected with two ends of an alternating current mains supply, the absorption capacitor is connected in parallel between a first output end and a second output end of the rectifying bridge, one end of the choke coil is connected with a first output end of the rectifying bridge, the other end of the choke coil is connected with one end of the energy storage capacitor and is connected to the parallel resonant capacitor and the heating coil, and the other end of the energy storage capacitor is connected with a second output end of the rectifying bridge.
6. A protection arrangement for an electromagnetic heating system according to claim 5, characterized in that an input of said forward voltage surge detection circuit is connected to a first output of said rectifier bridge for detecting an input voltage of said electromagnetic heating system.
7. A protection arrangement for an electromagnetic heating system according to claim 6, characterized in that the forward voltage surge detection circuit comprises:
the rectifier bridge comprises a fourth resistor, a fifth resistor and a sixth resistor which are connected in series, wherein one end of the fourth resistor is connected with a first output end of the rectifier bridge, the other end of the fourth resistor is connected with one end of the fifth resistor, the other end of the fifth resistor is connected with one end of the sixth resistor, the other end of the sixth resistor is grounded, the fifth resistor is connected with a second capacitor in parallel, the sixth resistor is connected with a seventh resistor and a third capacitor which are connected in series in parallel, and a second node is arranged between the other end of the fifth resistor and one end of the sixth resistor;
a second diode having an anode connected to the second node;
and the positive input end of the second comparator is connected with the cathode of the second diode, the negative input end of the second comparator is connected with a second reference voltage, and the output end of the second comparator is connected with the first signal input end of the trigger circuit.
8. A protection device for an electromagnetic heating system according to claim 1, wherein said switching tube overvoltage detection circuit comprises:
the switch comprises an eighth resistor and a ninth resistor which are connected in series, wherein one end of the eighth resistor is connected with a collector of the switch tube, the other end of the eighth resistor is connected with one end of the ninth resistor, the other end of the ninth resistor is grounded, a third node is arranged between the other end of the eighth resistor and one end of the ninth resistor, and the ninth resistor is connected with a fourth capacitor in parallel;
and a positive input end of the third comparator is connected with the third node, a negative input end of the third comparator is connected with a third reference voltage, and an output end of the third comparator is connected with a third signal input end of the trigger circuit.
9. A protection device for an electromagnetic heating system according to claim 1, wherein said drive circuit comprises:
a collector of the first NPN triode is connected with a preset power supply through a tenth resistor, a base of the first NPN triode is connected with the output end of the trigger circuit, and an emitter of the first NPN triode is connected with the base of the switching tube;
the emitter of the first PNP triode is connected with the emitter of the first NPN triode, the base of the first PNP triode is connected with the base of the first NPN triode, and the collector of the first PNP triode is grounded after being connected with the emitter of the switching tube;
a collector of the second NPN triode is connected to a base of the first NPN triode and one end of an eleventh resistor, respectively, and the other end of the eleventh resistor is connected to the preset power supply, and an emitter of the second NPN triode is grounded;
the circuit comprises a twelfth resistor and a thirteenth resistor which are connected in series, wherein one end of the twelfth resistor is connected with a base electrode of the second NPN triode, the other end of the twelfth resistor is connected with one end of the thirteenth resistor, the other end of the thirteenth resistor is connected with a preset power supply, a fourth node is arranged between the other end of the twelfth resistor and one end of the thirteenth resistor, and the fourth node is connected with a controller.
10. An electromagnetic heating system, characterized by comprising a protection device of an electromagnetic heating system according to any one of claims 1-9.
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| CN110492432B (en) * | 2019-08-19 | 2024-03-26 | 深圳市独尊科技开发有限公司 | High-voltage excitation device |
| CN110611500B (en) * | 2019-08-30 | 2023-09-01 | 鑫汇科研究院(佛山)有限公司 | Semiconductor switching device control circuit, method and device and electromagnetic heating device |
| CN111244887A (en) * | 2020-03-05 | 2020-06-05 | 深圳市鑫汇科股份有限公司 | Protection circuit and surge detection method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201323447Y (en) * | 2008-12-12 | 2009-10-07 | 深圳市鑫汇科科技有限公司 | Voltage and current surge protection circuit for electromagnetic oven |
| CN205179404U (en) * | 2015-11-26 | 2016-04-20 | 佛山市顺德区美的电热电器制造有限公司 | IGBT's overvoltage crowbar among electromagnetic heating device and electromagnetic heating device |
| CN205846689U (en) * | 2016-06-20 | 2016-12-28 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and protection device thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201323447Y (en) * | 2008-12-12 | 2009-10-07 | 深圳市鑫汇科科技有限公司 | Voltage and current surge protection circuit for electromagnetic oven |
| CN205179404U (en) * | 2015-11-26 | 2016-04-20 | 佛山市顺德区美的电热电器制造有限公司 | IGBT's overvoltage crowbar among electromagnetic heating device and electromagnetic heating device |
| CN205846689U (en) * | 2016-06-20 | 2016-12-28 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating system and protection device thereof |
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