Oven protection circuit and oven

Abstract

The oven protection circuit comprises a first gating circuit, a second gating circuit, a relay and a single chip microcomputer, the first gating circuit comprises a first switch, a first direct current source, a second direct current source and a gating switch, the first end of the first switch is connected with the first direct current source, the second end of the first switch is connected with the first end of a coil, and the second end of the first switch is connected with the second end of the coil. The first end of the gating switch is connected with the second DC source, and the second end is connected with the control end of the first switch; the second gating circuit comprises a second switch and a gating signal detection circuit, the input end of the gating signal detection circuit is connected with the second end of the gating switch, the output end of the gating signal detection circuit is connected with the single-chip microcomputer, the single-chip microcomputer is connected with the control end of the second switch, the first end of the second switch is connected with the second end of the coil, and the second end is grounded. The two gating circuits are arranged on the coil branch of the relay, the two gating circuits are independent in function, and the relay can be disconnected under the condition that any gating circuit fails independently, so that the safety of the oven is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical appliances, and in particular to an oven protection circuit and an oven. Background Art

[0002] Currently, the door control detection of existing oven products (including ovens or steam ovens) usually detects the switch status, then uses a resistor-capacitor circuit to stabilize the switch detection signal, and then inputs the switch detection signal into the chip. After the chip monitors the state change of the door control switch, it performs corresponding actions, such as turning on or off the oven light, cutting off or starting the heating system, and continuing to execute unfinished set programs after closing the door.

[0003] It can be seen that the current solution for oven products to detect whether the door is open relies on the chip to determine whether the switch status is present, and then use the software program inside the chip to execute the action. When the chip is in an abnormal state, such as software recognition errors or program errors, the oven will continue to run and heat with the door open, posing a safety hazard. Summary of the Invention

[0004] In order to solve at least one of the above-mentioned technical problems, the present invention provides an oven protection circuit and an oven.

[0005] According to some embodiments of the present invention, an oven protection circuit is provided, comprising a first gating circuit, a second gating circuit, a relay, and a single-chip microcomputer, wherein the first gating circuit comprises a first switch, a first DC source, a second DC source, and a gate-controlled switch, wherein a first end of the first switch is connected to the first DC source, a second end of the first switch is connected to a first end of a coil of the relay, a first end of the gate-controlled switch is connected to the second DC source, and a second end of the gate-controlled switch is connected to a control end of the first switch; the second gating circuit comprises a second switch and a gate-controlled signal detection circuit, an input end of the gate-controlled signal detection circuit is connected to the second end of the gate-controlled switch, an output end of the gate-controlled signal detection circuit is connected to the single-chip microcomputer, the single-chip microcomputer is connected to the control end of the second switch, a first end of the second switch is connected to the second end of the coil, and a second end of the second switch is grounded.

[0006] Based on the above scheme, two different gating circuits are set to control the relay, wherein the first gating circuit is a hardware control circuit, which uses a gate switch to directly control the on and off of the relay coil and the first DC source. The second gating circuit is a software control circuit, which requires the microcontroller to send a corresponding switch control signal according to the gate switch state recognition result, thereby controlling the on and off of the relay coil and the ground. Through two different control logics, the relay can be ensured to be disconnected normally when a problem occurs with the microcontroller, thereby improving the circuit safety.

[0007] In some possible implementations, the first switch is a MOS transistor, and the first gate-controlled circuit further includes a first transistor, wherein the collector of the first transistor is connected to the gate of the MOS transistor, the emitter of the first transistor is grounded, and the base of the first transistor is connected to the second end of the gate-controlled switch.

[0008] Based on the above solution, the first switch uses a MOS tube, and the MOS tube and the first transistor form a two-stage controller circuit, which can reduce the overall power consumption of the circuit, optimize the switching speed and response, enhance anti-interference and stability, and its simple circuit structure helps to reduce costs.

[0009] In some possible implementations, the second DC source is a voltage source, and the first gate-controlled circuit further includes a resistor-capacitor circuit, wherein a first end of the resistor-capacitor circuit is connected to a second end of the gate-controlled switch, and a second end of the resistor-capacitor circuit is connected to a base of the first transistor.

[0010] Based on the above solution, the voltage signal of the second DC source is converted into a current signal suitable for the first transistor through the resistor-capacitor circuit, thereby accurately driving the first transistor and improving circuit stability.

[0011] In some possible embodiments, the gate signal detection circuit includes a second transistor, the base of the second transistor is connected to the second end of the gate switch, the emitter of the second transistor is grounded, the collector of the second transistor is connected to the first end of the first detection resistor, the second end of the first detection resistor is connected to the second DC source, the first end of the first detection resistor is also connected to the first end of the second detection resistor, and the second end of the second detection resistor is connected to the single-chip microcomputer.

[0012] Based on the above scheme, the voltage signal after the gate switch is turned on is detected by a transistor circuit, so that the state of the gate switch can be accurately identified, and the gate signal detection circuit implemented based on the transistor can isolate the first gate circuit and the second gate circuit, making the two gate circuits independent of each other.

[0013] In some possible implementations, the second switch includes a third transistor and a fourth transistor, the base of the third transistor is connected to the single-chip microcomputer, the collector of the third transistor is connected to the second end of the coil, the emitter of the third transistor is connected to the collector of the fourth transistor, and the base of the fourth transistor is connected to the single-chip microcomputer.

[0014] Based on the above scheme, the third transistor and the fourth transistor form a two-stage amplification circuit, which can quickly respond to the high-frequency signal sent by the microcontroller, improve the switching response speed, and have high anti-interference performance, thereby enhancing the stability of the gate circuit.

[0015] In some possible embodiments, the second gating circuit further includes a differential circuit and a clamping circuit, the differential circuit includes a first resistor and a first capacitor, the first end of the first resistor is connected to the single-chip microcomputer, the second end of the first resistor is connected to the first end of the first capacitor, and the single-chip microcomputer is used to send a square wave signal to the differential circuit; the clamping circuit includes a first diode and a second diode, the second end of the first capacitor is respectively connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is respectively connected to the base of the third transistor and the base of the fourth transistor, and the anode of the second diode is grounded.

[0016] Based on the above scheme, a differential circuit and a clamping circuit are added. The differential circuit can convert the time edge signal of the square wave sent by the single-chip microcomputer into a spike pulse signal, thereby realizing the function of pulse width modulation control, while the clamping circuit limits the spike pulse signal to a safe range, preventing the third and fourth transistors from being damaged by high-voltage shocks.

[0017] In some possible implementations, the oven protection circuit includes one or more second gating circuits and one or more relays, and the second gating circuits and the relays are provided in a one-to-one correspondence.

[0018] Based on the above solution, the second gating circuits are set in a one-to-one correspondence with the relays, which can realize simultaneous control of multiple components, and the software control circuits of each component are independent of each other.

[0019] In some possible implementations, the single chip microcomputer is connected to a differential analog-to-digital converter, and two input terminals of the differential analog-to-digital converter are respectively connected to the first terminal and the second terminal of the gate-controlled switch.

[0020] Based on the above scheme, a differential analog-to-digital converter is used to detect the voltage at both ends of the gate-controlled switch. Whether the voltage at both ends is consistent can be used to determine whether the switch contacts are aged and failed, thereby ensuring the normal and effective operation of the gate-controlled switch and improving circuit safety.

[0021] In some possible implementations, the single chip microcomputer is connected to an angle sensor, and the angle sensor is used to detect the opening and closing angle of the oven door.

[0022] Based on the above scheme, the opening and closing angle of the oven door is detected by an angle sensor. According to the consistency between the sensor detection result and the door switch signal detection result, it can be judged whether the door switch is abnormal, thereby avoiding damage to the door switch that causes the relay to fail to disconnect correctly.

[0023] According to other embodiments of the present invention, an oven is provided, comprising an oven protection circuit according to any one of the above embodiments.

[0024] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

[0025] Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions and advantages of the embodiments of this specification or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 A system block diagram of an oven protection circuit according to an embodiment of the present invention is shown; Figure 2 shows a circuit structure diagram of a first gating circuit according to an embodiment of the present invention; Figure 3 FIG. 1 shows a circuit structure diagram of a gate signal detection circuit according to an embodiment of the present invention; Figure 4 A diagram showing a connection structure between a gating signal detection circuit and a first gating circuit according to an embodiment of the present invention is shown; Figure 5 shows a circuit structure diagram of a second gating circuit according to an embodiment of the present invention; Figure 6 shows a structural block diagram of a second gating circuit according to an embodiment of the present invention; Figure 7 A control logic block diagram of an oven protection circuit according to an embodiment of the present invention is shown; Figure 8 Shown is a circuit structure diagram of a heating system relay according to an embodiment of the present invention; Figure 9 A circuit structure diagram of a second gate control circuit of a heating system according to an embodiment of the present invention is shown; Figure 10 FIG. 4 shows a circuit structure diagram of a single chip microcomputer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the embodiments described are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this invention.

[0029] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0031] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0032] The term "and / or" herein simply describes an association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can represent the existence of three situations: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" herein refers to any combination of at least two of any one or more of a plurality of items. For example, "at least one of A, B, and C" can represent any one or more elements selected from the set consisting of A, B, and C.

[0033] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention may be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of the present invention.

[0034] Currently, the door control detection of existing oven products (including ovens or steam ovens) usually detects the switch status, then uses a resistor-capacitor circuit to stabilize the switch detection signal, and then inputs the switch detection signal into the chip. After the chip monitors the state change of the door control switch, it performs corresponding actions, such as turning on or off the oven light, cutting off or starting the heating system, and continuing to execute unfinished set programs after closing the door.

[0035] However, the above-mentioned solution for detecting whether the door is open relies on the chip function. The chip needs to correctly judge whether the detection switch status is present, and then use the internal software program of the chip to execute the action. When the chip is in an abnormal state, such as software recognition error or program runaway, it will cause the oven to continue to run and heat with the door open, posing a safety hazard.

[0036] In the related art, there is also a solution of directly setting the gate-controlled switch in series on the relay coil branch. When the chip is abnormal, the relay can still be disconnected by the gate-controlled switch. However, this solution also has defects: directly connecting the gate-controlled switch in series with the relay coil branch, the gate-controlled switch is easily damaged and fails under the impact of large current, and there may be multiple components based on the oven door opening and closing action control. If the number of gate-controlled switches is increased simultaneously, the complexity of the circuit structure will increase, the design cost will increase, and the control response speed will also be affected, thereby affecting the stability.

[0037] To solve the above-mentioned technical problems, an embodiment of the present invention provides an oven protection circuit. The circuit is provided with two gate circuits on the coil branch of a relay. The two gate circuits are respectively controlled by hardware and software. In response to the opening and closing of the oven door, the two gate circuits operate simultaneously. Since the two gate circuits function independently, if either gate circuit fails alone, the relay can be disconnected, thereby ensuring the safety of the oven.

[0038] For details, please refer to Figure 1 The oven protection circuit includes a first gating circuit, a second gating circuit, a relay and a single-chip microcomputer; the first gating circuit includes a first switch, a first DC source, a second DC source and a gate-controlled switch, the first end of the first switch is connected to the first DC source, the second end of the first switch is connected to the first end of the coil of the relay, the first end of the gate-controlled switch is connected to the second DC source, and the second end of the gate-controlled switch is connected to the control end of the first switch; the second gating circuit includes a second switch and a gate-controlled signal detection circuit, the input end of the gate-controlled signal detection circuit is connected to the second end of the gate-controlled switch, the output end of the gate-controlled signal detection circuit is connected to the single-chip microcomputer, the single-chip microcomputer is connected to the control end of the second switch, the first end of the second switch is connected to the second end of the coil, and the second end of the second switch is grounded.

[0039] In the above circuit structure, the gate-controlled switch is turned off when the oven door is open and turned on when the oven door is closed. After the gate-controlled switch is turned on, the control end of the first switch receives a signal from the second DC source and turns on. The turned-on first switch connects the first DC source to the first end of the relay coil; the gate-controlled signal detection circuit detects the signal at the second end of the gate-controlled switch and sends a gate-controlled detection signal to the microcontroller. In response to the gate-controlled detection signal, the microcontroller controls the second switch to turn on and the second end of the coil to be grounded. At this point, the first DC source, the first switch, the coil and the second switch form a path, and the coil is energized to control the contact closure.

[0040] In this embodiment, the first gate control circuit is a hardware control circuit that controls the on / off state of the first switch via a gate switch, thereby controlling the on / off state of the first DC source. When the gate switch is off, the first DC source cannot send a DC signal to external components. The second gate control circuit is a software control circuit that detects the on / off state of the gate switch via a gate signal detection circuit. The gate signal detection circuit feeds the gate detection signal back to the microcontroller. The microcontroller determines whether the oven door is closed based on its own program and sends a control signal to the second switch when the oven door is closed. Based on this configuration, combining the hardware and software control circuits, the gate switch directly controls the on / off state of the first DC source based on the oven door's opening and closing motions. The software control circuit, implemented in the microcontroller, detects and analyzes the gate switch state to control whether the coil is grounded. Only when both the hardware and software control circuits are on can the relay coil branch conduct electricity, thereby closing the relay contacts. Combining the hardware and software control circuits improves the reliability and stability of the protection circuit, avoiding the problem of circuit failure caused by abnormal control of a single switch.

[0041] The present invention does not limit the specific selection of the first switch and the second switch, wherein the first switch should have a large current characteristic to facilitate access to a large DC source, and the second switch should have good control characteristics and be able to be controlled by a digital signal or analog signal sent by the microcontroller.

[0042] In some embodiments, please refer to Figure 2 The first switch is a MOS transistor, and the first gate control circuit further includes a first triode. The collector of the first triode is connected to the gate of the MOS transistor, the emitter of the first triode is grounded, and the base of the first triode is connected to the second end of the gate control switch. Based on the above circuit structure, the first gate control circuit is a two-level control circuit consisting of a triode and a MOS transistor. After the gate control switch is turned on, the base of the first triode receives a signal from the second DC source and turns on. After the first triode turns on, it controls the MOS transistor to turn on. The reason for using a MOS transistor as the first switch is that the MOS transistor has high current characteristics. Since the first switch is connected to the first power supply and the relay coil respectively, and the voltage of the first power supply is relatively high, the MOS transistor can ensure that the subsequent load can operate normally and will not be damaged by the high current impact. If a triode or other switch with low current characteristics is used, the subsequent load may not operate normally, and the triode or switch may also be damaged by the high current impact.

[0043] The arrangement of the first transistor in conjunction with the MOS transistor in this embodiment offers several advantages. Specifically, the transistor's current amplification properties enable it to convert weak control signals (low-current signals) into sufficient current to drive the MOS transistor's gate. Furthermore, the transistor's high current output capability significantly shortens the MOS transistor's turn-on / off time, thereby reducing switching losses. Furthermore, while the transistor's on-state voltage drop exhibits some losses, the overall system power consumption is still lower compared to directly driving the MOS transistor with high current. The high-speed switching characteristics of the transistor, combined with the MOS transistor's low on-resistance, significantly improve circuit response speed. The transistor's low input impedance effectively suppresses noise interference in the control signal, while the MOS transistor's high input impedance prevents load effects on the preceding circuit. Compared to dedicated driver ICs, the transistor drive solution eliminates the need for complex level conversion circuits and requires fewer peripheral components (such as pull-up resistors and current-limiting resistors), significantly reducing hardware cost and PCB area. Therefore, the combination of the first transistor and MOS transistor reduces overall circuit power consumption, optimizes switching speed and response, enhances interference resistance and stability, and its simple circuit structure contributes to cost reduction.

[0044] In the above embodiment, if Figure 2 As shown, the first DC source is a voltage source, grounded via a capacitor. The output terminal of the first DC source is directly connected to the drain of the MOS transistor. The source of the MOS transistor is connected to the coil as the power output terminal. A voltage divider resistor R80 is provided between the drain and gate of the MOS transistor. A protective resistor R84 is also provided between the gate of the MOS transistor and the collector of the first transistor. Through the voltage divider resistor R80 and the protective resistor R84, when the first transistor is turned on, the gate of the MOS transistor can recognize the voltage signal and turn on. In one specific embodiment, the voltage amplitude of the first DC source is 12V.

[0045] It should be understood that this embodiment does not limit the first DC source to being only a voltage source. In other words, the first DC source may also be a current source. In this case, the connection method of each terminal of the first transistor and the MOS transistor needs to be adjusted accordingly, which is not described in detail in this embodiment. Similarly, this embodiment does not limit the specific type of the second DC source. In other words, the second DC source may be a voltage source or a current source.

[0046] In some embodiments, the second DC source is a voltage source, and the voltage amplitude of the second DC source is 5V. Since the first transistor needs to be turned on by a current signal, the first gate circuit also includes a resistor-capacitor circuit, the first end of the resistor-capacitor circuit is connected to the second end of the gate switch, and the second end of the resistor-capacitor circuit is connected to the base of the first transistor. The resistor-capacitor circuit converts the voltage signal of the second DC source into a current signal suitable for the first transistor, thereby accurately driving the first transistor and improving circuit stability. The resistor-capacitor circuit is a circuit including resistors and capacitors. The resistor in the resistor-capacitor circuit is used to convert the voltage signal into a current signal, and the capacitor in the resistor-capacitor circuit is used for filtering to improve signal stability.

[0047] This embodiment does not limit the specific structure of the resistor-capacitor circuit. In a specific implementation, Figure 2 As shown, the RC circuit consists of a resistor R67, a resistor R68 and a capacitor C42. The first end of the resistor R67 is connected to the second end of the gate-controlled switch, and the second end of the resistor R67 is grounded. The first end of the resistor R68 is connected to the second end of the gate-controlled switch, and the second end of the resistor R68 is connected to the base of the first transistor. The first end of the capacitor C42 is connected to the second end of the resistor R68, and the second end of the capacitor C42 is grounded.

[0048] In other embodiments, the second DC source may also be a current source, which may be directly connected to the base of the first transistor or connected to the base of the first transistor through a shunt circuit to ensure that the base of the first transistor can detect the adapted control signal.

[0049] In the oven protection circuit of the present invention, the gate signal detection circuit is used to detect the on / off state of the gate switch. The present invention does not limit the specific structure of the gate signal detection circuit. It should be understood that the specific structure of the gate signal detection circuit is related to the detection principle and the type of the second DC source. Specifically, when the gate signal detection circuit directly detects the operation of the gate switch, its detection principle may be electromagnetic induction, optical induction, or the like. For example, when the gate switch is a contact switch, the gate signal detection circuit may include a light sensor that detects the operation of the contact switch and thereby determines the on / off state of the contact switch. When the gate signal detection circuit indirectly detects the operation of the gate switch, for example, by detecting an electrical parameter (current or voltage) of the branch circuit in which the gate switch is located, the detection function may be implemented using components such as a semiconductor switch, a current transformer, or an electrical parameter sampler.

[0050] In some embodiments, please refer to Figure 3 and Figure 4The gate signal detection circuit includes a second transistor, the base of the second transistor being connected to the second end of the gate-controlled switch, the emitter of the second transistor being grounded, the collector of the second transistor being connected to the first end of a first detection resistor R72, the second end of the first detection resistor R72 being connected to a second DC source, the first end of the first detection resistor R72 being further connected to the first end of a second detection resistor R74, and the second end of the second detection resistor R74 being connected to a single-chip microcomputer. The second DC source is a voltage source, and a resistor-capacitor circuit is provided between the base of the second transistor and the second end of the gate-controlled switch. When the gate-controlled switch is turned on, a voltage signal from the first DC source is converted into a current signal by the resistor-capacitor circuit and transmitted to the base of the second transistor, thereby turning on the second transistor. The second DC source then applies a voltage signal to the first detection resistor R72, causing current to flow through the first detection resistor R72. When the current flows through the second detection resistor R74, the single-chip microcomputer determines the switching state of the gate-controlled switch by detecting the voltage value of the second detection resistor R74.

[0051] In a further embodiment, a resistor R69 is further provided between the base of the second transistor and the second end of the resistor-capacitor circuit, a resistor R70 is further provided between the base and the emitter of the second transistor, the second end of the second detection resistor R74 is connected to the first end of the capacitor C46, ​​and the second end of the capacitor C46 is grounded.

[0052] In an embodiment of the present invention, the second switch should be a switch that can identify the control signal of the microcontroller, that is, the second switch can be a transistor, an IGBT or other types of semiconductor switch tubes, and the second switch can be a composite switch circuit formed by a combination of multiple semiconductor switch tubes, so as to accurately identify and quickly respond to the control signal of the microcontroller.

[0053] In some embodiments, please refer to Figure 5 and Figure 6 The second switch includes a third transistor and a fourth transistor. The base of the third transistor is connected to the single-chip microcomputer, the collector of the third transistor is connected to the second end of the coil, the emitter of the third transistor is connected to the collector of the fourth transistor, and the base of the fourth transistor is connected to the single-chip microcomputer. Based on the above structure, the third transistor and the fourth transistor form a two-stage amplifier circuit. On the one hand, the two-stage transistor amplifier circuit can amplify the current signal and quickly respond to the high-frequency signal sent by the single-chip microcomputer, thereby improving the response speed of the transistor switch, thereby ensuring that the relay coil is quickly energized and improving the response speed of the relay. In addition, the two transistors are synchronously turned on and off. If either transistor is damaged, the circuit can be disconnected, thereby improving the safety performance of the circuit. The two-stage amplifier circuit composed of two transistors also has high anti-interference performance, which can further enhance the stability of the gate control circuit.

[0054] In further embodiments, please refer to Figure 5 and Figure 6 The second gating circuit also includes a differential circuit and a clamping circuit. The differential circuit includes a first resistor and a first capacitor. The first end of the first resistor is connected to the single-chip microcomputer, and the second end of the first resistor is connected to the first end of the first capacitor. The single-chip microcomputer is used to send a square wave signal to the differential circuit; the clamping circuit includes a first diode and a second diode. The second end of the first capacitor is respectively connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is respectively connected to the base of the third transistor and the base of the fourth transistor, and the anode of the second diode is grounded.

[0055] Based on the above circuit structure, the microcontroller can perform pulse-width modulation (PWM) control on the second switch. Specifically, the microcontroller transmits a high-frequency pulse-width modulation (PWM) signal. Since the PWM signal is a square wave, the differential circuit converts the timing signal of the square wave sent by the microcontroller into a spike pulse signal, thereby implementing the PWM control function. The clamping circuit limits the spike pulse signal to a safe range, preventing the base of the third and fourth transistors from being damaged by high-voltage surges, and ensuring that the signals transmitted to the bases of the third and fourth transistors remain within the specified range.

[0056] In actual application scenarios, the door switch may fail. For example, in some cases, the door switch shorts. In this case, after the oven door is opened, the first switch will still be turned on. Because the door switch is short-circuited, the gate signal detection circuit can still detect the path signal. The microcontroller determines that the door switch is closed, controls the second switch to turn on, and then controls the relay to turn on. This obviously poses a safety hazard. In other cases, the contacts of the door switch are poor, resulting in the first switch not being properly turned on after the oven door is closed, or the first switch's conduction state being unstable, affecting the stability and reliability of the circuit control. Long-term poor contact of the contacts can also eventually cause the door switch to burn out and short-circuit.

[0057] To address the aforementioned technical issues, it's necessary to inspect and determine the gate-controlled switch, promptly detecting any poor contact, allowing for early warning and maintenance measures. Normally, after the gate-controlled switch is closed, the voltage difference across the switch should be less than or equal to a certain value—that is, the voltage difference should be approximately equal or even. However, if the gate-controlled switch contacts erode or experience poor contact, the voltage difference across the switch can become excessively large. Therefore, this can be determined by detecting the voltage across the switch.

[0058] In some embodiments, the microcontroller is connected to a differential analog-to-digital converter, with the two input terminals of the differential analog-to-digital converter being connected to the first and second terminals of the gate-controlled switch, respectively. The differential analog-to-digital converter can convert analog signals into digital signals, and the voltage division of the differential analog-to-digital converter is negligible, so accurate voltage measurements can be obtained based on the differential analog-to-digital converter. It is understood that the differential analog-to-digital converter can also be replaced with other detection components or detection circuits, such as a differential current detection circuit, a high-precision voltmeter, etc.

[0059] In addition to detecting the voltage across the door switch, the oven door movement and the door switch status can also be separately detected, and the door switch abnormality can be determined based on the correlation between the two. The present invention is not limited to the components and principles for detecting oven door movement. For example, a distance sensor based on electromagnetic induction, infrared, or light sensing can be used to detect the distance between the oven door and the main body.

[0060] In some embodiments, the microcontroller is connected to an angle sensor that detects the oven door's opening and closing angle. This sensor accurately determines the door's movement. The angle sensor can optionally be configured as an angle encoder, which can directly send digital signals to the microcontroller without requiring additional conversion circuitry.

[0061] The above embodiments have described in detail an oven protection circuit of the present invention. The circuit is configured with two independent gate control circuits, which can disconnect the relay when either the gate control switch or the single-chip microcomputer chip fails, thereby ensuring that the corresponding function is turned off after the oven door is opened. The control logic of the oven protection circuit is as follows: Figure 7 shown.

[0062] In addition to setting up the dual judgment logic for the relay as mentioned above, another purpose of independently setting up the first gating circuit and the second gating circuit is that the first gating circuit can serve as a switching control circuit for the first DC source. When it has multiple gating functions, a relay is set up separately for each gating function, and a second gating circuit is set up for each relay.

[0063] In some embodiments, the oven protection circuit includes one or more second gate control circuits and one or more relays, and the second gate control circuits and the relays are arranged in a one-to-one correspondence.

[0064] In a specific embodiment, please refer to Figures 8-10The oven is provided with four heating tubes, namely an upper outer heating tube, an upper inner heating tube, a back heating tube, and a lower heating tube. Each heating tube is provided with a relay and a second switch. The first end of each relay coil is connected to the second end of the first switch, and the second end of each relay coil is connected to the first end of the corresponding second switch. The second end of the second switch is grounded, and the control ends of the four second switches are connected to the four output pins of the single-chip microcomputer. Based on the above structure, the oven protection circuit is applied in the heating system. Each heating tube is provided with an independent second switch. The relay for each heating tube is jointly controlled by the first gate circuit and the second gate circuit. The control circuits of multiple heating tubes share a first gate circuit, a gate signal detection circuit, and a single-chip microcomputer. This can reduce the cost of multiple control circuits and help reduce the cost of the entire device.

[0065] It should be understood that, in addition to the heating tube, other door-controlled components may also be controlled by the oven protection circuit of the above embodiment, such as the oven light, oven fan, etc.

[0066] An embodiment of the present invention further provides an oven, comprising an oven protection circuit according to any one of the above embodiments.

[0067] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An oven protection circuit, characterized in that: comprising a first gating circuit, a second gating circuit and a relay, The first gate-controlled circuit includes a first switch, a first DC source, a second DC source, and a gate-controlled switch, wherein a first end of the first switch is connected to the first DC source, a second end of the first switch is connected to a first end of the coil of the relay, a first end of the gate-controlled switch is connected to the second DC source, and a second end of the gate-controlled switch is connected to a control end of the first switch; The second gating circuit includes a second switch, a gating signal detection circuit and a single-chip microcomputer. The input end of the gating signal detection circuit is connected to the second end of the gating switch, the output end of the gating signal detection circuit is connected to the single-chip microcomputer, the single-chip microcomputer is connected to the control end of the second switch, the first end of the second switch is connected to the second end of the coil, and the second end of the second switch is grounded.

2. The oven protection circuit according to claim 1, characterized in that: The first switch is a MOS tube, and the first gate control circuit further includes a first transistor, the collector of the first transistor is connected to the gate of the MOS tube, the emitter of the first transistor is grounded, and the base of the first transistor is connected to the second end of the gate control switch.

3. The oven protection circuit according to claim 2, characterized in that: The second DC source is a voltage source, and the first gate-controlled circuit further includes a resistor-capacitor circuit, a first end of the resistor-capacitor circuit is connected to the second end of the gate-controlled switch, and a second end of the resistor-capacitor circuit is connected to the base of the first transistor.

4. The oven protection circuit according to claim 3, characterized in that: The gate signal detection circuit includes a second transistor, the base of the second transistor is connected to the second end of the gate switch, the emitter of the second transistor is grounded, the collector of the second transistor is connected to the first end of a first detection resistor, the second end of the first detection resistor is connected to the second DC source, the first end of the first detection resistor is also connected to the first end of a second detection resistor, and the second end of the second detection resistor is connected to the single-chip microcomputer.

5. The oven protection circuit according to claim 4, characterized in that: The second switch includes a third transistor and a fourth transistor, the base of the third transistor is connected to the single chip microcomputer, the collector of the third transistor is connected to the second end of the coil, the emitter of the third transistor is connected to the collector of the fourth transistor, and the base of the fourth transistor is connected to the single chip microcomputer.

6. The oven protection circuit according to claim 5, characterized in that: The second gating circuit further includes a differential circuit and a clamping circuit, the differential circuit including a first resistor and a first capacitor, a first end of the first resistor being connected to the single-chip microcomputer, a second end of the first resistor being connected to a first end of the first capacitor, and the single-chip microcomputer being configured to send a square wave signal to the differential circuit; The clamping circuit includes a first diode and a second diode, the second end of the first capacitor is respectively connected to the anode of the first diode and the cathode of the second diode, the cathode of the first diode is respectively connected to the base of the third transistor and the base of the fourth transistor, and the anode of the second diode is grounded.

7. The oven protection circuit according to claim 6, characterized in that: The oven protection circuit includes one or more second gate control circuits and one or more relays, and the second gate control circuits and the relays are arranged in a one-to-one correspondence.

8. The oven protection circuit according to claim 7, characterized in that: The single chip microcomputer is connected to a differential analog-to-digital converter, and two input terminals of the differential analog-to-digital converter are respectively connected to the first terminal and the second terminal of the gate-controlled switch.

9. The oven protection circuit according to claim 8, characterized in that: The single chip microcomputer is connected to an angle sensor, and the angle sensor is used to detect the opening and closing angle of the oven door.

10. An oven, characterized in that: An oven protection circuit comprising any one of claims 1-9.

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