Food processor cup cover opening and closing protection circuit

Abstract

The cup cover opening and closing protection circuit of the food processor disclosed by the present disclosure relates to the technical field of food processing and comprises a switching power supply, a switching module, a level conversion module, a variable frequency motor driving module and a main control module. The switching module is electrically connected with the power supply end of the variable frequency motor driving module through a first branch and is used for providing working power supply to the variable frequency motor driving module. The switching module is electrically connected with the input end of the level conversion module through a second branch. The level conversion module is configured to output a detection level signal to the detection end of the main control module in response to the signal output by the second branch. When the cup cover is opened, the main control module is caused to stop outputting a driving signal to the variable frequency motor driving module, so as to stop the variable frequency motor. In this way, the safety required by the new national standard is ensured. Meanwhile, through the timing design of soft stopping and then hard breaking, the opening cover trigger occupies less space, and the control circuit is safe and reliable, the power device operates stably, the service life is low, and the long-term reliability of the product is ensured.

Description

Technical Field

[0001] This disclosure relates to the field of food processing technology, and in particular to a cup lid opening and closing protection circuit for a food processing machine. Background Technology

[0002] Currently, food processors such as soymilk makers and blenders pose a serious threat to personal safety if the user accidentally opens the lid. To ensure user safety, the new national standard imposes strict requirements on these products: the motor must stop running immediately when the lid is opened.

[0003] Existing food processors with soy milk making capabilities include a cup assembly and a main unit. The cup assembly consists of a cup body and a grinding blade housed within it. The grinding blade is driven by a motor to rotate and process ingredients such as soybeans, black beans, grains, and fish to create beverages like soy milk, rice porridge, rice paste, and thick soup. Because the cup contains the grinding blade, if the user opens the lid while the machine is in operation, or if the lid is not closed when starting the food processor, an open lid signal is sent to the main control module. Based on this signal, the main control module either prevents the food processor from starting or uses software to stop the motor from rotating the grinding blade, thus preventing mechanical injury from the user's fingers touching the rotating blade's edge after the lid is opened. Regarding this safety requirement for opening the lid of a food processor, the national standard GB / T 4706.30-2024 stipulates that "for the stirrer, except for the lid, other detachable parts shall not be removed. During the test, a test fixture similar to Type B in GB / T 16842-2016 shall be used, but a circular baffle with a diameter of 125mm shall be used instead of a non-circular baffle, and the distance from the tip of the test fixture to the baffle shall be 100mm." For food processors that meet this requirement, combined with the requirements of national standard GB 4706.19-2008, and taking into account the safety protection of users when making hot drinks, the motor can be stopped by disconnecting the low-voltage control when the lid of the food processor is opened.

[0004] However, the newly revised national standard GB / T 4706.19-2024 has added stricter requirements for food processing machines, specifically soy milk makers. Clause 22.40 of the standard stipulates that "for soy milk makers, any switches used to control the motor should also disconnect those electronic circuits that, if they fail, would cause the machine to fail to meet the requirements of this document." In other words, for food processing machines with soy milk functions, the method of stopping the motor by disconnecting the low-voltage power supply when the lid is opened does not meet the requirements of the newly revised national standard. The motor must be stopped by disconnecting the power supply to the drive motor or directly disconnecting the high-voltage power supply after the lid is opened to meet the safety requirements for opening the lid in the new national standard. For traditional blenders driven by series-wound motors, connecting a high-voltage safety switch in series on the neutral line of the main circuit, and disconnecting the neutral line when the lid is opened, meets the requirements of the newly revised national standard GB / T 4706.19-2024 for disconnecting the high-voltage power supply when the lid is opened. However, the solution of disconnecting the neutral wire via a high-voltage switch when the lid is opened has problems. The high-voltage switch is large, while the triggering space in a food processor is very limited. Furthermore, due to the high voltage in the main circuit, disconnecting the neutral wire causes significant wear and tear on the overall circuit and components, especially the electrical sparks generated at the moment the switch opens and closes, affecting the reliability of the control circuit and the lifespan of critical components. This is especially true for food processors driven by three-phase brushless variable frequency motors. Currently, variable frequency motors in food processors offer multiple advantages such as low noise, stepless speed regulation, and stable crushing performance. However, compared to traditional food processors driven by series-wound motors, variable frequency motor-driven food processors have more complex control circuits and higher requirements for safety and reliability.

[0005] Therefore, if those skilled in the art want food processors to meet the safety requirement of the newly revised national standard GB / T 4706.19-2024, which stipulates that the variable frequency motor stops driving when the lid of a food processor with a soy milk function is opened, they must revert to the method mentioned in the background of this application, which involves disconnecting the neutral wire with a safety switch to achieve the purpose of controlling the variable frequency motor to stop driving by disconnecting the high voltage. However, this approach inevitably sacrifices more space occupied by hardware switches, trigger reliability, and the lifespan of power devices. In food processors driven by variable frequency motors, how to reduce the space occupied by the lid-opening trigger while ensuring the safety and reliability of the control circuit, the stable operation of power devices, low lifespan loss, and meeting the safety requirement of the newly revised national standard GB / T 4706.19-2024 that the variable frequency motor reliably stops driving when the lid is opened is an urgent technical problem to be solved. Utility Model Content

[0006] This disclosure provides a cup lid opening and closing protection circuit for a food processing machine, which effectively solves the technical problem in the prior art of how to reduce the space occupied by the lid opening trigger while ensuring the safety and reliability of the control circuit, the stable operation of the power devices, and the low life loss, and meets the safety requirement of reliable stopping of the variable frequency motor when the cup lid is opened in the newly revised national standard GB / T 4706.19-2024.

[0007] Specifically, this disclosure provides a cup lid opening and closing protection circuit for a food processor, which is applied to a food processor. The food processor includes a cup body with a receiving space and a cup lid disposed on the cup body. The cup body includes a cup lid opening, which is closed when the cup lid is closed. A pulverizing blade driven by a variable frequency motor is disposed in the receiving space.

[0008] The protection circuit includes a switching power supply, a switching module, a level conversion module, a variable frequency motor drive module, and a main control module. The variable frequency motor drive module is used to drive the variable frequency motor. The switching module is electrically connected to the power supply terminal of the variable frequency motor drive module through a first branch, and is used to provide operating power to the variable frequency motor drive module. The switching module is electrically connected to the input terminal of the level conversion module through a second branch. The level conversion module is configured to output a detection level signal to the detection terminal of the main control module in response to the signal output from the second branch, so as to stop the main control module from outputting the drive signal to the variable frequency motor drive module when the cup lid is opened, thereby stopping the variable frequency motor. The output terminal of the switching power supply is electrically connected to the switching module. The switching module is used to disconnect the connection between the switching power supply and the first and second branches when the cup lid is opened, and to connect the connection between the switching power supply and the first and second branches when the cup lid is closed. The protection circuit also includes a first energy storage module, which is used to discharge to the power supply terminal of the variable frequency motor drive module and delay the power-off of the power supply terminal of the variable frequency motor drive module when the cup lid is opened.

[0009] Optionally, the protection circuit further includes a second energy storage module; the positive terminal of the first energy storage module is connected to the output terminal of the switch module and the power supply terminal of the variable frequency motor drive module, and the positive terminal of the second energy storage module is connected to the output terminal of the switch module and the level conversion module; the negative terminals of the first and second energy storage modules are grounded; wherein, the capacity of the first energy storage module is greater than the capacity of the second energy storage module.

[0010] Optionally, the first energy storage module includes a first electrolytic capacitor, and the second energy storage module includes a second electrolytic capacitor; the positive terminal of the first electrolytic capacitor serves as the positive terminal of the first energy storage module, and the negative terminal of the first electrolytic capacitor serves as the negative terminal of the first energy storage module; the positive terminal of the second electrolytic capacitor serves as the positive terminal of the second energy storage module, and the negative terminal of the second electrolytic capacitor serves as the negative terminal of the second energy storage module.

[0011] Optionally, the capacitance of the first electrolytic capacitor is C1, and the capacitance of the second electrolytic capacitor is C2, where C1 ≥ K. C2, K≥10.

[0012] Optionally, the protection circuit also includes a first resistor connected in parallel with the second energy storage module.

[0013] Optionally, the protection circuit further includes a first diode and a second diode; the anode of the first diode is connected to the first branch, and the cathode of the first diode is connected to the anode of the first energy storage module and the power supply terminal of the variable frequency motor drive module; the anode of the second diode is connected to the second branch, and the cathode of the second diode is connected to the anode of the second energy storage module and the input terminal of the level conversion module.

[0014] Optionally, the level conversion module includes a transient voltage suppression diode, an N-type transistor, a P-type transistor, a second resistor, a third resistor, and a fourth resistor. The negative terminal of the transient voltage suppression diode is connected to the second branch, and the positive terminal of the transient voltage suppression diode is connected to the base of the N-type transistor through the second resistor. The base of the N-type transistor is also grounded through the third resistor. The emitter of the N-type transistor is grounded, and the collector of the N-type transistor is coupled to the base of the P-type transistor. The emitter of the P-type transistor is connected to the first voltage terminal, and the collector is coupled to the detection terminal of the main control module. The collector of the P-type transistor is also grounded through the fourth resistor.

[0015] Optionally, the resistance of the second resistor is A2, and the resistance of the third resistor is A3, where A3 ≥ P. A2, P≥5.

[0016] Optionally, the reverse breakdown voltage of the transient voltage suppression diode is U1, 10V≤U1≤14V, and the output voltage of the switching power supply is 15V.

[0017] Optionally, the switch module includes a first switch, which is a low-voltage switch.

[0018] The technical solution provided in this disclosure has the following advantages compared with the prior art: 1. This disclosure introduces two mechanisms: soft stop and hard power-off. At the soft stop level, a level conversion module is introduced. When the lid is opened, a detection level signal is sent to the main control module, triggering a "soft stop" to prevent the blade from injuring the user. The power supply to the variable frequency motor drive module is gradually disconnected only after the main control module stops outputting drive signals, providing valuable buffer time for power devices such as IGBTs. This allows the IGBTs to safely complete the transition from the on to the off state with sufficient power support, without entering the dangerous amplification region or half-voltage state due to a sudden voltage drop. This completely eliminates the risk of IGBT explosion and variable frequency motor drive module burnout, ensuring long-term product reliability and significantly improving the lifespan and stability of the food processor. This disclosure still allows for final power cut-off via a physical switch, ensuring the safety requirements of the new national standard.

[0019] 2. At the level of hard power cut-off, this disclosure introduces a switch module that directly disconnects the power supply from the variable frequency motor drive module when the cup lid is opened, thus achieving the cut-off of high voltage without relying on software control. This fundamentally eliminates the risk of the variable frequency motor failing to stop due to software failure, thereby meeting the requirements of the new national standard.

[0020] 3. This disclosure integrates both soft stop and hard power-off mechanisms. Even if the software control fails under extreme conditions, the hardware switch module can subsequently disconnect the power supply, providing a solid safety barrier. At the same time, it avoids the risk of the motor failing to stop due to software failure when using only low-voltage switches (such as reed switches or Hall effect sensors).

[0021] 4. The switching module and switching power supply introduced in this disclosure are located in the low-voltage control circuit, where the voltage and current are much lower than those in the high-voltage main circuit. Therefore, the switching module in this disclosure can be implemented using a low-voltage switch. Compared to setting a high-power switch in the high-voltage main circuit, the switching module in the low-voltage circuit is smaller and more conducive to the optimized design of the internal space of the food processing machine. The switching module performs switching operations under low voltage and low current conditions, greatly reducing component losses and avoiding the generation of electrical sparks. This not only improves the reliability of the control circuit but also significantly extends the service life of key components. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0023] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The diagram shown is a structural schematic of a cup lid opening and closing protection circuit for a food processor provided in an embodiment of this disclosure; Figure 2 The diagram shown is another structural schematic of the cup lid opening and closing protection circuit of the food processor provided in this embodiment of the present disclosure; Figure 3 The diagram shown is a circuit diagram of a cup lid opening and closing protection circuit for a food processor provided in an embodiment of this disclosure; Figure 4 This is a timing diagram showing the level changes of the first electrolytic capacitor, the second electrolytic capacitor, and the input terminals of the variable frequency motor drive module when the switching module goes from being turned on to being turned off. Detailed Implementation

[0025] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0026] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0027] The food processing machine is driven by a variable frequency motor, which is driven by a variable frequency motor drive module. This drive module uses IGBTs as its core components to achieve its driving function. Pages 30-33 of the textbook *Power Electronics Technology and MATLAB Simulation* (Second Edition), a textbook for the "Twelfth Five-Year Plan" of ordinary higher education published by China Electric Power Press (ISBN 978-7-5123-6067-9), disclose the structure and working principle of the Insulated Gate Bipolar Transistor (IGBT), as well as its characteristics and main parameters. Based on the working principle and characteristics of IGBTs, the food processing machine generates a three-phase AC voltage by precisely controlling the PWM duty cycle of six IGBTs, thereby driving the variable frequency motor.

[0028] Based on the working principle and performance parameters of IGBTs, those skilled in the art fully understand that the power supply terminal of the IGBT drive module should be within the safe voltage range of the saturation region so that the variable frequency motor can normally drive the pulverizer to process food. That is, the current power supply voltage of the variable frequency motor drive module is within the normal operating voltage range. When the switching transistor of the variable frequency drive module is normally turned off, the current power supply voltage of the variable frequency motor drive module is normally within the cutoff voltage range.

[0029] A well-known domestic manufacturer of variable frequency motor drive modules, such as Hangzhou Silan Microelectronics Co., Ltd., has published an electronic manual for an intelligent power module (IPM, i.e., variable frequency motor drive module) on its official website. The specific model is SDM10C60TA2B1, and the URL is: https: / / www.silan.com.cn / index.php / product / details / 2501.html. The manual clearly states that the typical value of the control power supply voltage Vcc for this model is 15V, with a minimum of 13.5V and a maximum of 16.5V. This means the normal operating voltage range of the variable frequency motor drive module is between 13.5V and 16.5V, with a typical value of 15V. While the manual provides an optimal control power supply voltage Vcc value, in actual operation, the normal operating voltage range can be flexibly adjusted according to the actual operating conditions based on the actual characteristics of the IGBT, such as between 10V and 18V, with a typical value of 15V.

[0030] Based on the existing technologies described above, both textbooks and chip electronics manufacturers have explained and limited the operating voltage required for normal operation of variable frequency motor drive modules based on the IGBT working principle. They all clarify that the operating voltage of the variable frequency motor drive module should be maintained within the normal operating voltage range that allows the IGBT to be driven safely and reliably. That is, the power supply voltage of the variable frequency motor drive module should be in the saturation region or in the cutoff region after normal shutdown. Whether based on textbooks or common knowledge in the field, it is clear that directly disconnecting the power supply to the variable frequency motor drive module is not allowed; that is, the power supply voltage of the variable frequency motor drive module should not be in the amplification region. Otherwise, it will directly lead to abnormal conduction of the switching transistor, such as short circuits in the upper and lower bridge arms of the IGBT or an uncontrollable "half-on, half-off" state of the switching transistor, directly causing a sudden increase in the temperature of the switching transistor, resulting in the risk of transistor explosion or even machine explosion. In the food processing machine field, there is a core contradiction between the strict requirements of the new national standard for lid opening safety and existing technologies. One side of the contradiction lies in the mandatory requirement of the new national standard: to ensure user safety, the motor must be stopped immediately and reliably when the lid is opened. This essentially requires a solution that disconnects the high-voltage circuit, as low-voltage solutions relying on software control are at risk of failure. The other side of the contradiction lies in the "reverse teaching" of existing technology. In the field of variable frequency motor drives, a fundamental and widely accepted reverse teaching is that the +15V (i.e., the aforementioned typical value) power supply to the variable frequency motor drive module should never be directly disconnected during normal motor operation. Textbooks and chip manufacturers (such as Silan Microelectronics) explicitly warn that doing so will cause a voltage drop, causing the power devices (IGBTs) of the variable frequency motor drive module to enter the non-saturated operating region. This can result in damage to the devices, or even tube explosion, burning out the entire drive module, or even causing the machine to explode. Based on this, those skilled in the art have no choice but to opt for opening the cover to disconnect the neutral wire, as a second-best option. Therefore, how to solve the technical problem of large hardware space occupation, high overall circuit and component losses, and especially the electrical sparks that occur at the moment of switch opening and closing, affecting the reliability of the control circuit and the lifespan of key components, while meeting the new national standard for safely and reliably stopping the motor drive by opening the cover, is a crucial issue that urgently needs to be addressed.

[0031] Figure 1 The diagram shown is a structural schematic of a cup lid opening and closing protection circuit for a food processor provided in this embodiment of the present disclosure. Please refer to it. Figure 1This disclosure provides a lid opening and closing protection circuit for a food processor. The food processor includes a cup body with a receiving space and a lid disposed on the cup body. The cup body includes a lid opening, which is closed when the lid is closed. A pulverizing blade driven by a variable frequency motor is disposed within the receiving space. It should be noted that the "lid" in this disclosure does not simply refer to a component directly covering the cup body opening, but rather refers to any component that can block the opening of the cup body and provide a safety control function for opening the lid. This can manifest in two main forms: the first is direct blocking, the most common form, where the lid directly covers the cup body, completely sealing the opening. The second is indirect blocking, for example, in a food processor containing a main unit, an outer lid is disposed on the main unit, and an inner lid is disposed above the cup body located inside the main unit. When the outer lid is closed on top of the inner lid, it also provides blocking and protection. In this case, the outer lid is equivalent to the lid defined in this application, and its opening and closing action can serve as a signal to trigger the safety protection circuit. It should also be noted that the protection circuit provided in this disclosure is not only applicable to traditional products with simple structures such as soy milk makers and blenders, but can also be flexibly applied to new food processing machines with more complex structures, including a main unit and multiple lids, in order to improve its wide applicability.

[0032] The protection circuit provided in this disclosure includes a switching power supply 10, a switching module 20, a level conversion module 30, a variable frequency motor drive module 40, and a main control module 50. The variable frequency motor drive module 40 is used to drive a variable frequency motor 60. The switching module 20 is electrically connected to the power supply terminal VCC of the variable frequency motor drive module 40 through a first branch L1, and is used to provide operating power to the variable frequency motor drive module 40. The switching module 20 is electrically connected to the input terminal of the level conversion module 30 through a second branch L2. The level conversion module 30 is configured to output a detection level signal to the detection terminal I / O of the main control module 50 in response to the signal output from the second branch L2. When the lid is opened, the main control module 50 stops outputting drive signals to the variable frequency motor drive module 40, thereby stopping the variable frequency motor 60. The output terminal of the switching power supply 10 is electrically connected to the switching module 20. The switching module 20 is used to disconnect the switching power supply 10 from the first branch L1 and the second branch L2 when the lid is opened, and to connect the switching power supply 10 from the first branch L1 and the second branch L2 when the lid is closed. The protection circuit also includes a first energy storage module 70, which is used to discharge to the power supply terminal VCC of the variable frequency motor drive module 40 and delay the power supply to the power supply terminal VCC of the variable frequency motor drive module 40 when the lid is opened.

[0033] In the food processing machine industry, there is a core contradiction between the new national standard's stringent requirements for lid opening safety and existing technologies. One side of the contradiction lies in the mandatory requirement of the new standard: to ensure user safety, the motor must be stopped immediately and reliably when the lid is opened. This essentially requires a solution that disconnects high-voltage power, as low-voltage solutions relying on software control are at risk of failure. The other side of the contradiction lies in the "reverse teaching" of existing technologies. In the field of variable frequency motor drives, a basic and widely accepted reverse teaching is that the +15V power supply to the variable frequency motor drive module should never be directly disconnected during normal motor operation. Textbooks and chip manufacturers (such as Silan Microelectronics) explicitly warn that doing so will cause a voltage drop, causing the power devices (IGBTs) of the variable frequency motor drive module to enter the non-saturated operating region. This can result in damage to the devices, or even tube explosion, burning out the entire drive module, or even causing the machine to explode. Based on this, those skilled in the art are forced to choose the less desirable option of disconnecting the neutral wire by opening the lid. Therefore, it is urgent to solve the technical problems that need to be addressed, such as how to ensure the safe and reliable stopping of the motor drive when the lid is opened, while meeting the new national standard, and how to solve the problems caused by the lid triggering the high-voltage switch to open and close, which results in large hardware space occupation, high overall circuit and component losses, and especially the electric sparks that occur at the moment the switch is opened and closed, affecting the reliability of the control circuit and the service life of key components.

[0034] In this disclosure, when the cup lid is closed, the switch module 20 is turned on, simultaneously supplying electrical energy from the switching power supply 10 to the first branch L1 and the second branch L2. The first branch L1 supplies power to the variable frequency motor drive module 40, enabling it to drive the motor normally, and simultaneously charges the first energy storage module 70, preparing it with energy. The second branch L2 supplies power to the level conversion module 30, putting it in standby mode. The main control module 50 normally outputs drive signals to the variable frequency motor drive module 40.

[0035] When the lid is opened, the switch module 20 instantly disconnects, cutting off the connection between the switching power supply 10 and the first branch L1 and the second branch L2. Due to the power interruption, the level conversion module 30 immediately sends a detection level signal to the main control module 50. Upon receiving the signal, the main control module 50 immediately stops outputting drive signals to the variable frequency motor drive module 40, causing the variable frequency motor to begin decelerating and enter a "soft stop" state. Simultaneously, the first energy storage module 70 begins discharging, providing a brief buffer power supply to the variable frequency motor drive module 40 to achieve a "soft shutdown" buffer effect. This design ensures that when the lid is opened, the main control module 50 can receive the signal and stop driving immediately, while the energy storage module provides power, offering the necessary buffer time for the variable frequency motor drive module 40 to safely shut down.

[0036] This disclosure introduces a first energy storage module 70, whose function is to provide a brief, continuous power supply to the variable frequency motor drive module 40 after the switch module 20 is disconnected, thereby achieving delayed shutdown. In practical applications, when the lid is opened, the switch module 20 is disconnected through a physical or electromagnetic mechanism (e.g., the separation of a magnet from a reed switch). The switch module 20 immediately sends a signal to the level conversion module 30, informing it that the lid is open. The level conversion module 30 quickly transmits this signal to the main control module 50. Upon receiving the signal, the main control module 50 immediately stops outputting drive signals to the variable frequency motor drive module 40. At this time, the motor begins to enter a soft-stop state. The first energy storage module 70 begins to discharge at the instant the switch module 20 is disconnected. This discharge process provides a brief power supply to the variable frequency motor drive module 40, ensuring that the variable frequency motor drive module 40 still has sufficient power to complete its internal shutdown process after the main control module 50 stops sending drive signals, thereby achieving delayed mechanical shutdown. The discharge characteristics of the energy storage module (usually a capacitor) determine that the voltage will not drop sharply like when the switch is instantly disconnected. It provides a brief, smooth voltage drop. This smooth voltage drop offers valuable buffer time for power devices such as IGBTs. During this short period, the power supply voltage of the variable frequency motor drive module 40 remains within its normal operating range. Because of this buffer, the IGBT devices can safely complete the transition from the on to the off state with sufficient power support, without entering the dangerous amplification region or half-voltage state due to a sudden voltage drop. The power supply to the variable frequency motor drive module 40 is only completely cut off after the first energy storage module 70 has exhausted its power. At this point, the motor has completely stopped driving, and the power devices such as IGBTs are in a safe state, thus preventing damage from voltage drops. This solution, by introducing the first energy storage module 70, ensures that the power supply voltage of the variable frequency motor drive module 40 remains in the saturation region when the main control module 50 stops the drive signal, thereby avoiding damage to power devices due to voltage drops below the critical point. This achieves safe motor shutdown while protecting core components.

[0037] Therefore, in the cup lid opening and closing protection circuit of the food processor mentioned in this disclosure, when the cup lid is opened, the motor can be stopped by two independent mechanisms (soft stop and hard power cut-off), rather than relying solely on a single high-voltage switch.

[0038] At the soft-stop level, this disclosure introduces a level conversion module 30, which sends a detection level signal to the main control module 50 when the lid is opened, triggering a "soft stop". Upon receiving the aforementioned detection level signal indicating the lid is open, the main control module 50 immediately stops outputting drive signals to the variable frequency motor drive module 40, effectively transmitting a stop command to the variable frequency motor 60, causing the variable frequency motor 60 to stop rotating. In this disclosure, the moment the main control module 50 stops outputting drive signals to the variable frequency motor drive module 40 is earlier than the moment the power supply terminal VCC of the variable frequency motor drive module 40 is de-energized. Therefore, during the "soft stop" process, the power supply terminal VCC of the variable frequency motor drive module 40 is not de-energized; that is, the software-controlled stop process occurs before the physical de-energization of the variable frequency motor drive module 40. Furthermore, when the main control module 50 stops outputting drive signals to the variable frequency motor drive module 40, the voltage at the power supply terminal of the variable frequency motor drive module 40 remains within its normal operating voltage range. This ensures that the power supply voltage of the variable frequency motor drive module 40 remains in the saturation region when the main control module 50 stops outputting drive signals, preventing damage to power devices due to voltage drops below the critical point. This achieves safe motor shutdown while protecting core components. The power supply to the variable frequency motor drive module 40 is gradually disconnected only after the main control module 50 stops outputting drive signals, providing valuable buffer time for power devices such as IGBTs. This allows the IGBTs to safely complete the transition from the on to the off state with sufficient power support, without entering the dangerous amplification region or half-voltage state due to a sudden voltage drop. Therefore, voltage drops will not impact power devices such as IGBTs, solving the problem of IGBT damage or module burnout that may occur when directly disconnecting the +15V power supply in existing technologies.

[0039] At the level of hard power cut-off, this disclosure introduces a switch module 20, which directly disconnects the power supply of the switching power supply 10 and the power supply of the variable frequency motor drive module 40 when the cup lid is opened, thereby achieving the cut-off of high voltage without relying on software control. This fundamentally eliminates the risk that software failure will cause the variable frequency motor 60 to fail to stop, thus meeting the requirements of the new national standard.

[0040] In summary, this disclosure introduces both soft-stop and hard-shutdown mechanisms, achieving final high-voltage disconnection through a physical switch to ensure the safety requirements of the new national standard. Simultaneously, the timing design of soft-stop followed by hard-shutdown completely eliminates the risk of IGBT tube explosion and module burnout, guaranteeing long-term product reliability and significantly improving the lifespan and stability of the food processing machine. Furthermore, this disclosure integrates both soft-stop and hard-shutdown mechanisms, ensuring that even if the software control malfunctions under extreme conditions, the hardware switch module 20 can subsequently disconnect the power supply, providing a robust safety safeguard. It also avoids the risk of the motor failing to stop due to software malfunctions when using only low-voltage switches (such as reed switches or Hall effect sensors).

[0041] Furthermore, the switch module 20 and switching power supply 10 used in this disclosure are located in the low-voltage control circuit, where the voltage and current are much lower than those in the high-voltage main circuit. Compared to setting a high-power switch in the high-voltage main circuit, the switch module in the low-voltage circuit is smaller, which is more conducive to the optimized design of the internal space of the food processing machine. The switch module performs switching operations under low voltage and low current conditions, which greatly reduces component losses and avoids the generation of electrical sparks. This not only improves the reliability of the control circuit but also significantly extends the service life of key components.

[0042] In one optional embodiment of this disclosure, the first energy storage module 70 discharges until it stops supplying power to the variable frequency motor drive module 40, after the main control module 50 stops outputting drive signals to the variable frequency motor drive module 40 to control the variable frequency motor 60 to stop driving. That is, after the lid is opened, the main control module 50 immediately stops outputting drive signals to the variable frequency motor drive module 40. This is equivalent to issuing a "soft stop" command to the motor. During this stage, the drive module still has power to ensure that power devices such as IGBTs can safely enter a non-operating state. After the main control module 50 stops sending drive signals, the first energy storage module 70 begins to discharge. Its function is to briefly provide power to the variable frequency motor drive module 40 after the physical switch is turned off. This power supply process ensures that the power supply voltage does not instantly drop to a dangerous area, providing the necessary buffer time for the internal shutdown process of the variable frequency motor drive module 40. Only when the energy storage module is depleted and can no longer maintain power supply will the power supply to the variable frequency motor drive module 40 be completely cut off. At this point, since the motor has stopped driving, power devices such as IGBTs are in a safe state, and the final voltage drop will not cause any damage to the devices.

[0043] Figure 2 The diagram shown is another structural schematic of the cup lid opening and closing protection circuit of the food processor provided in this embodiment of the present disclosure. Figure 3 The diagram shown is a circuit diagram of a cup lid opening and closing protection circuit for a food processor provided in this embodiment of the present disclosure. Please refer to it. Figure 2 and Figure 3 In one optional embodiment of this disclosure, the protection circuit further includes a second energy storage module 80; the positive terminal of the first energy storage module 70 is connected to the output terminal of the switch module 20 and the power supply terminal of the variable frequency motor drive module 40, and the positive terminal of the second energy storage module 80 is connected to the output terminal of the switch module 20 and the level conversion module 30; the negative terminals of the first energy storage module 70 and the second energy storage module 80 are grounded; wherein, the capacity of the first energy storage module 70 is greater than the capacity of the second energy storage module 80.

[0044] After the switch module 20 is disconnected, the first energy storage module 70 provides continuous power to the variable frequency motor drive module 40. Since the variable frequency motor drive module 40 requires a certain amount of energy during the turn-off process to maintain the safe state of power devices such as IGBTs, the capacity of the first energy storage module 70 is designed to be larger to ensure sufficient energy to complete the "soft stop" process. After the switch module 20 is disconnected, the second energy storage module 80 acts as a filter, providing a cleaner and more stable DC power supply to the level conversion module 30. It also provides a brief power supply to the level conversion module 30 to ensure its accuracy and reliability when detecting signals. The main function of this module is to ensure that the level conversion module 30 has sufficient power to send the final turn-off signal to the main control module 50 at the moment the switch is disconnected. Because the level conversion module 30 itself has very low power consumption, its required energy is much less than that of the motor drive module; therefore, the capacity of the second energy storage module 80 can be designed to be smaller.

[0045] In this disclosure, the discharge time of the two energy storage modules can be precisely controlled by their capacity differences. The second energy storage module 80, with its smaller capacity, discharges rapidly, ensuring that the main control module 50 receives the shutdown signal immediately. The first energy storage module 70, with its larger capacity, provides a longer buffer time, ensuring that the variable frequency motor drive module 40 has sufficient power for safe shutdown. This allows for the rational allocation of energy storage module capacity based on the actual power consumption requirements of different modules. This ensures the reliability of critical functions (such as safe motor shutdown) while avoiding unnecessary cost waste. The dual-power supply design decouples the signal transmission and motor power supply buffer functions, resulting in higher system stability when dealing with the instantaneous disconnection of the switching module 20.

[0046] Furthermore, considering that there is usually some ripple voltage and high-frequency noise at the output of the switching power supply 10, the second energy storage module 80 is connected to the input of the level conversion module 30 and can act as a filter to absorb these voltage fluctuations and noise. This provides a cleaner and more stable DC power supply for the level conversion module 30, ensuring its accuracy and reliability when detecting signals. When the power supply voltage drops momentarily for some reason, the second energy storage module 80 will discharge to maintain voltage stability, preventing the level conversion module 30 from malfunctioning or failing due to insufficient power supply.

[0047] Please refer to Figure 3 In one optional embodiment of this disclosure, the first energy storage module 70 includes a first electrolytic capacitor EC1, and the second energy storage module 80 includes a second electrolytic capacitor EC2; the positive terminal of the first electrolytic capacitor EC1 serves as the positive terminal of the first energy storage module 70, and the negative terminal of the first electrolytic capacitor EC1 serves as the negative terminal of the first energy storage module 70; the positive terminal of the second electrolytic capacitor EC2 serves as the positive terminal of the second energy storage module 80, and the negative terminal of the second electrolytic capacitor EC2 serves as the negative terminal of the second energy storage module 80.

[0048] In this disclosure, both the first energy storage module 70 and the second energy storage module 80 are electrolytic capacitors. Electrolytic capacitors have high capacitance density, providing higher capacity within the same volume compared to other types of capacitors. The first electrolytic capacitor EC1, serving as the first energy storage module 70, is responsible for providing a brief and stable power supply to the variable frequency motor drive module 40 when the lid is opened. EC1 enables the first energy storage module 70 to store sufficient energy to provide the necessary buffer power supply time for the higher-power variable frequency motor drive module 40 after the switch module 20 is disconnected, allowing the variable frequency motor drive module 40 to safely complete the "soft stop" process while energized. The second electrolytic capacitor EC2, serving as the second energy storage module 80, is responsible for providing power to the level conversion module 30 at the instant the switch module 20 is disconnected. Since the power consumption of the level conversion module 30 is very low, the capacitance of the second electrolytic capacitor EC2 can be designed to be relatively small to ensure rapid discharge and timely triggering of the shutdown signal of the main control module 50.

[0049] Furthermore, electrolytic capacitors are mature and low-cost electronic components. This disclosure introduces a first electrolytic capacitor EC1 and a second electrolytic capacitor EC2 to achieve the precise power supply timing required by different modules in the circuit in a cost-effective and space-friendly manner, further ensuring the reliability and safety of the entire protection scheme.

[0050] In one optional embodiment of this disclosure, the capacitance of the first electrolytic capacitor EC1 is C1, and the capacitance of the second electrolytic capacitor EC2 is C2, wherein C1 ≥ K. C2, K≥10.

[0051] The primary task of the first electrolytic capacitor EC1 is to provide a shutdown buffer for the variable frequency motor drive module 40. After the motor stops driving, the drive module still needs to maintain power supply for a period of time to ensure that power devices (such as IGBTs) can safely complete their internal shutdown process. Since the drive module has relatively high power and requires more energy, the capacitance of the first electrolytic capacitor EC1 must be large enough. The primary task of the second electrolytic capacitor EC2 is to provide a signal transmission buffer for the level conversion module 30. The level conversion module 30 has very low power consumption; it only needs to provide power for a very short time at the moment the switch is turned off to ensure that the shutdown signal can be received by the main control module 50. Therefore, the capacitance of the second electrolytic capacitor EC2 can be very small. The energy required by the first electrolytic capacitor EC1 is at least ten times that required by the second electrolytic capacitor EC2. This precise capacitance design ensures that the timeliness of signal transmission and the safety of power shutdown are simultaneously satisfied throughout the entire safety protection process. Through this significant capacitance difference, a perfect timing sequence of "fast signal transmission" and "slow power disconnection" is achieved. The second electrolytic capacitor EC2 discharges rapidly, ensuring that the main control module 50 receives the signal immediately; the first electrolytic capacitor EC1 discharges slowly, ensuring that the drive module has sufficient time to safely shut down. This precise capacitance design avoids unnecessary waste. There is no need to configure a large-capacity capacitor for the low-power level conversion module 30, thus saving cost and PCB space. This quantitative design ensures that the shutdown signal and drive module shutdown process can be reliably completed even under different external environments, further improving the stability and safety of the entire circuit.

[0052] For example, C1 = 470 μF and C2 = 4.7 μF. However, this disclosure is not limited thereto.

[0053] Please continue to refer to this. Figure 4In one optional embodiment of this disclosure, the protection circuit further includes a first resistor R1 connected in parallel with the second energy storage module 80. When the cup lid is opened and the switch module 20 is disconnected, the charging of the second energy storage module 80 by the switching power supply 10 is cut off. At this time, the second energy storage module 80 will discharge rapidly through this parallel resistor. The discharge time of the capacitor is determined by its capacitance and the resistance in the circuit. By connecting a resistor with an appropriate resistance value in parallel, the discharge rate of the second energy storage module 80 can be precisely controlled. This ensures that at the moment the switch is disconnected, the second energy storage module 80 can quickly release the stored electrical energy to the level conversion module 30, enabling it to immediately send a shutdown signal to the main control module 50, thereby ensuring the rapid triggering of the shutdown signal and achieving a more timely "soft stop" of the motor. This disclosure further enhances the reliability of the entire safety protection circuit by connecting a resistor in parallel with the second energy storage module 80. It ensures that the opening action can be converted into an electrical signal as quickly as possible and transmitted to the main control module 50, so that the core step of "the main control module stops outputting drive signals to the frequency converter drive module" can be completed as early as possible before the actual power supply is cut off, providing more sufficient safety buffer time for the motor and power devices.

[0054] Please continue to refer to this. Figure 3 In one optional embodiment of this disclosure, the protection circuit further includes a first diode D1 and a second diode D2; the anode of the first diode D1 is connected to the first branch L1, and the cathode of the first diode D1 is connected to the anode of the first energy storage module 70 and the power supply terminal of the variable frequency motor drive module 40; the anode of the second diode D2 is connected to the second branch L2, and the cathode of the second diode D2 is connected to the anode of the second energy storage module 80 and the input terminal of the level conversion module 30.

[0055] In this disclosure, the first diode D1 and the second diode D2 primarily function as unidirectional conductors, ensuring that current can only flow from the switching power supply 10 to the energy storage module and not in the reverse direction. When the lid is closed, current can flow from the switching power supply 10 through the first branch L1 and the first diode D1 to charge the first energy storage module 70 and power the motor drive module. When the lid is open and the switching module 20 is disconnected, the power supply to the switching power supply 10 is cut off. At this time, the unidirectional conduction characteristic of the first diode D1 prevents current from flowing back from the first energy storage module 70 to the switching module 20, ensuring that all the electrical energy of the first energy storage module 70 is used to provide buffer power to the variable frequency motor drive module 40, achieving efficient energy utilization. Similarly, the second diode D2 ensures that current can only flow from the switching power supply 10 to the second energy storage module 80 and the level conversion module 30. When the switching module 20 is disconnected, it prevents current from flowing back, ensuring that the second energy storage module 80 can stably discharge to the level conversion module 30 through its parallel resistor to provide a timely shutdown signal.

[0056] This disclosure introduces two diodes. The unidirectional conduction characteristic of the two diodes effectively prevents the charge of the energy storage module from flowing back to the switching power supply 10 or the first branch L1 and the second branch L2 after the switching module 20 is disconnected, thereby avoiding energy loss. This design isolates the switching power supply 10 from the energy storage module and its downstream circuits. This not only protects the switching power supply 10 itself, but also enables the energy storage module to discharge more stably and controllably.

[0057] Please continue to refer to this. Figure 3 In one optional embodiment of this disclosure, the level conversion module 30 includes a transient voltage suppression diode D3, an N-type transistor Q1, a P-type transistor Q2, a second resistor R2, a third resistor R3, and a fourth resistor R4. The negative terminal of the transient voltage suppression diode D3 is connected to the second branch L2, and the positive terminal of the transient voltage suppression diode D3 is connected to the base of the N-type transistor Q1 through the second resistor R2. The base of the N-type transistor Q1 is also grounded through the third resistor R3. The emitter of the N-type transistor Q1 is grounded, and the collector of the N-type transistor Q1 is coupled to the base of the P-type transistor Q2 (a resistor may be provided between them). The emitter of the P-type transistor Q2 is connected to the first voltage terminal, and the collector is coupled to the detection terminal I / O of the main control module 50 (a resistor may be provided between the collector and the detection terminal). The collector of the P-type transistor Q2 is also grounded through the fourth resistor R4.

[0058] This disclosure introduces a transient voltage suppressor diode D3, i.e., a TVS diode. The cathode of the TVS diode is connected to the second branch L2, and the anode is connected to the base of the N-type transistor Q1. When an abnormal transient high voltage (such as static electricity or a surge) occurs on the second branch L2, the TVS diode will quickly conduct, clamping the high voltage to a safe level, thereby protecting the downstream N-type transistor Q1 and the entire circuit from damage.

[0059] With the lid closed, switch module 20 is turned on. The 15V voltage from the switching power supply is provided to the power supply terminal of the frequency converter drive module through the first branch L1 and to the TVS diode through the second branch L2. When the voltage across the TVS diode is higher than its breakdown voltage, the diode is in a breakdown state; when the voltage across the TVS diode is lower than its breakdown voltage, the diode is in an open circuit state. When switch module 20 is turned on, the voltage drop between the anode and cathode of the TVS diode is 15V. Ideally, the TVS diode should be in a breakdown state, therefore its breakdown voltage is lower than 15V. When the TVS diode breaks down, the voltage at the anode of the TVS diode provides current to the base of the N-type transistor Q1 through the second resistor R2. The N-type transistor Q1 turns on, and its collector becomes low. This low level pulls down the base of the P-type transistor Q2, turning it on. At this time, the collector of the P-type transistor Q2 (connected to the detection terminal of the main control module 50) is pulled up to the voltage of the first voltage terminal (high level in this example), and outputs a normal state signal, i.e., a high level signal, to the main control module 50.

[0060] With the lid open, switch module 20 is disconnected, the second branch L2 is de-energized, and the current to the base of N-type transistor Q1 is cut off. The third resistor R3 pulls the base potential down to ground, causing N-type transistor Q1 to turn off. The collector voltage of the N-type transistor increases, which in turn increases the base voltage of P-type transistor Q2, causing P-type transistor Q2 to turn off. At this time, the collector of P-type transistor Q2 is grounded through the fourth resistor R4, outputting a low-level detection signal to the main control module 50.

[0061] In the level conversion module 30 provided in this disclosure, the TVS diode provides robust transient voltage protection, enhancing the reliability of the circuit in complex electromagnetic environments. The switching of two transistors ensures that the detection signal output to the main control module 50 is a clear high or low level, avoiding unstable intermediate voltage states and ensuring accurate judgment by the main control module 50. Under normal operating conditions, the current in the circuit, through precise resistor design, can be kept at a low level, thereby reducing the overall power consumption of the module.

[0062] It should be noted that the above embodiments of this disclosure are only illustrated by the example that the level signal received by the detection terminal I / O of the main control module 50 is a high-level signal when the cup lid is closed and a low-level signal when the cup lid is open. However, this disclosure does not use this as an example. In some other embodiments of this disclosure, the level signal received by the detection terminal I / O of the main control module 50 may also be manifested according to different specific circuit structures: the level signal received by the detection terminal I / O of the main control module 50 is a low-level signal when the cup lid is closed and a high-level signal when the cup lid is open.

[0063] In one optional embodiment of this disclosure, the resistance of the second resistor R2 is A2, and the resistance of the third resistor R3 is A3, where A3 ≥ P. A2, P≥5.

[0064] In this disclosure, the second resistor R2 is located between the TVS diode and the base of the N-type transistor, and its function is to limit current. When the second branch L2 is energized, the second resistor R2 limits the current flowing to the base of the N-type transistor, preventing excessive base current from damaging the transistor. The third resistor R3 is connected between the base of the N-type transistor and ground, and its function is to act as a pull-down resistor. When the second branch L2 is de-energized, the third resistor R3 quickly pulls the base voltage of the transistor down to ground level, ensuring that the N-type transistor is reliably cut off. This disclosure sets A3 ≥ P. A2, P ≥ 5 means that the resistance A3 of the pull-down resistor (third resistor R3) is much larger than the resistance A2 of the current-limiting resistor (second resistor R2). When the second branch L2 is de-energized, the resistance of the third resistor R3 is large enough to quickly pull the base voltage of the N-type transistor down to zero, thus completely cutting it off. This ensures that the base voltage of the P-type transistor Q2 can reliably rise, thereby cutting off the P-type transistor Q2 and ultimately outputting a low-level signal. The large resistance of the third resistor R3, in conjunction with the collector resistor of the N-type transistor Q1, enables rapid signal level switching. When the N-type transistor Q1 is conducting, the current flowing through the second resistor R2 and the third resistor R3 can be precisely controlled at a low level, thereby reducing the static power consumption of the entire level conversion module 30.

[0065] Please combine Figure 2 and Figure 3 In one optional embodiment of this disclosure, the reverse breakdown voltage of the transient voltage suppression diode D3 is U1, 10V≤U1≤14V, and the output voltage of the switching power supply 10 is 15V.

[0066] In this disclosure, the output voltage of the switching power supply 10 is 15V, which is higher than the reverse breakdown voltage (U1) of the TVS diode. This means that under normal operating conditions, the TVS diode is in reverse cutoff. At this time, current can flow normally through the second resistor R2 to the base of the N-type transistor Q1, enabling the level conversion module 30 to operate normally. When a transient high voltage (e.g., electrostatic discharge or surge) higher than 15V occurs in the second branch L2, the TVS diode will quickly enter the reverse breakdown state. Since its breakdown voltage U1 (10V-14V) is lower than the 15V of the switching power supply 10, the TVS diode will clamp the voltage within a safe range. This effectively prevents high-voltage pulses from damaging sensitive components such as the downstream N-type transistor Q1. This parameter configuration perfectly balances the normal function and protection function of the circuit. Under normal conditions, the TVS diode does not affect signal transmission; while in case of abnormality, it can quickly activate protection to ensure the reliability of the level conversion module 30. This design further improves the stability and durability of the entire safety protection circuit in harsh electromagnetic environments.

[0067] When the voltage across a TVS diode is higher than its breakdown voltage, the TVS diode is in a breakdown state; when the voltage across it is lower than its breakdown voltage, it is in an open-circuit state. Based on this characteristic, when switch module 20 is turned on, the voltage drop across the anode and cathode of the TVS diode is 15V. At this point, it is desirable for the TVS diode to be in a breakdown state. Therefore, the recommended reverse breakdown voltage for the TVS diode can be lower than 14V. However, to allow for a certain soft turn-off time, a breakdown voltage above 10V is desirable. This is because when a high-power switching transistor turns on below 8V, it will not be able to turn on effectively, causing most of the energy to accumulate in the PN junction, leading to heat generation and ultimately device damage. Therefore, the reverse breakdown voltage of the TVS diode is between 10V and 14V, and 12V can be selected specifically. Please refer to [reference needed]. Figure 4 , Figure 4This is a timing diagram showing the voltage changes of the first electrolytic capacitor EC1, the second electrolytic capacitor EC2, and the input terminals of the variable frequency motor drive module 40 when the switching module 20 switches from on to off. When the switching module 20 switches from on to off, the voltage across the second electrolytic capacitor EC2 drops from 15V. Between 15V and 12V, the TVS diode is in the on state. At this time, the voltage is divided by the second resistor R2 and the fourth resistor R4, which provides voltage to the base of the N-type transistor Q1. Generally, when the resistance of the third resistor R3 is greater than five times the resistance of the second resistor R2, the N-type transistor Q1 can be in a saturated state, and the collector of the N-type transistor Q1 is in a low-level state. This low level pulls down the base of the P-type transistor Q2, turning it on. At this time, the collector of P-type transistor Q2 (connected to the detection terminal of the main control module 50) is pulled high to the voltage of the first voltage terminal VCC (high level in this embodiment), outputting a normal state signal to the main control module 50, that is, the level of the detection terminal I / O of the main control module 50 is a high-level detection signal. When the voltage on EC2 continues to drop from 12V, the TVS transistor is in the off state. At this time, the voltage divider between the second resistor R2 and the third resistor R3 provides 0V to the base of the transistor, which can make the N-type transistor Q1 in the off state. The collector voltage of the N-type transistor increases, which will increase the base voltage of the P-type transistor, causing the P-type transistor Q2 to be cut off. At this time, the collector of P-type transistor Q2 is grounded through the fourth resistor R4, outputting a low-level detection signal to the main control module 50, and the level of the detection terminal I / O of the main control module 50 is a low-level detection signal. Thus, through the above circuit, the final feedback is that when the switch module 20 is turned on, the detection terminal I / O of the main control module 50 is at a high level; when the switch module 20 is turned off, the detection terminal I / O of the main control module 50 is at a low level. Therefore, through the above circuit, the 15V switching of the switching power supply 10 is converted into a 5V level change, which is then provided to the main control module 50 for detection.

[0068] Please continue to refer to this. Figure 3In one optional embodiment of this disclosure, the switch module 20 includes a first switch S1, which is a low-voltage switch, such as a reed switch or a Hall element. Traditional low-voltage switch solutions typically rely on software to detect changes in their state and control the motor. If the software malfunctions, the motor may fail to stop, posing a serious safety hazard and thus failing to meet the stringent requirements of the new national standard. Although this disclosure also uses a low-voltage switch, its function is drastically different from traditional solutions. In this disclosure, the low-voltage switch (first switch S1) not only acts as a signal trigger but also directly as a physical switch to disconnect the power supply. When the lid is opened, the low-voltage switch (such as a reed switch) immediately disconnects. After the low-voltage switch disconnects, the power supply to the switching power supply 10 is cut off. At this time, the first energy storage module 70 begins to discharge, continuing to supply power to the motor drive module. During this brief power supply buffer period, the main control module 50 receives the lid opening signal and immediately stops outputting the drive signal, causing the variable frequency motor 60 to enter a safe shutdown state. Only after the energy storage module has finished discharging is the power supply to the variable frequency motor drive module 40 completely disconnected. This design relies entirely on the cooperation of the low-voltage switch and the energy storage module, eliminating the need for a bulky and costly high-voltage switch, thus greatly simplifying the product's structural design and reducing manufacturing costs. Furthermore, the low-voltage switch is compact and easily integrated into the product's compact structure. Although a low-voltage switch is used in this disclosure, it still achieves a "soft stop first, hard disconnect" safety sequence through the buffering effect of the energy storage module, effectively protecting critical power devices such as IGBTs and complying with the requirements of the new national standard. Optionally, the first switch S1 in this disclosure is a 15V low-voltage switch with a very small current, less than 0.1A, effectively meeting the requirements for small-size installations.

[0069] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0070] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cup lid opening and closing protection circuit for a food processing machine, applied to a food processing machine, characterized in that, The food processing machine includes a cup body with a receiving space and a cup lid disposed on the cup body. The cup body includes a cup lid opening, which is closed when the cup lid is closed. The receiving space is provided with a pulverizing blade driven by a variable frequency motor. The protection circuit includes a switching power supply, a switching module, a level conversion module, a variable frequency motor drive module, and a main control module. The variable frequency motor drive module is used to drive the variable frequency motor. The switching module is electrically connected to the power supply terminal of the variable frequency motor drive module via a first branch, and is used to provide operating power to the variable frequency motor drive module; the switching module is electrically connected to the input terminal of the level conversion module via a second branch, and the level conversion module is configured to output a detection level signal to the detection terminal of the main control module in response to the signal output from the second branch, so as to stop the main control module from outputting drive signals to the variable frequency motor drive module when the cup lid is opened, thereby stopping the variable frequency motor; The output terminal of the switching power supply is electrically connected to the switching module. The switching module is used to disconnect the switching power supply from the first branch and the second branch when the cup lid is opened, and to connect the switching power supply from the first branch and the second branch when the cup lid is closed. The protection circuit also includes a first energy storage module, which is used to discharge to the power supply terminal of the variable frequency motor drive module and delay the power supply terminal of the variable frequency motor drive module when the cup lid is opened.

2. The cup lid opening and closing protection circuit according to claim 1, characterized in that, The protection circuit further includes a second energy storage module; the positive terminal of the first energy storage module is connected to the output terminal of the switching module and the power supply terminal of the variable frequency motor drive module, and the positive terminal of the second energy storage module is connected to the output terminal of the switching module and the level conversion module; the negative terminals of the first energy storage module and the second energy storage module are grounded; The capacity of the first energy storage module is greater than that of the second energy storage module.

3. The cup lid opening and closing protection circuit according to claim 2, characterized in that, The first energy storage module includes a first electrolytic capacitor, and the second energy storage module includes a second electrolytic capacitor; the positive terminal of the first electrolytic capacitor serves as the positive terminal of the first energy storage module, and the negative terminal of the first electrolytic capacitor serves as the negative terminal of the first energy storage module; the positive terminal of the second electrolytic capacitor serves as the positive terminal of the second energy storage module, and the negative terminal of the second electrolytic capacitor serves as the negative terminal of the second energy storage module.

4. The cup lid opening and closing protection circuit according to claim 3, characterized in that, The capacitance of the first electrolytic capacitor is C1, and the capacitance of the second electrolytic capacitor is C2, where C1 ≥ K. C2, K≥10.

5. The cup lid opening and closing protection circuit according to claim 2, characterized in that, The protection circuit also includes a first resistor connected in parallel with the second energy storage module.

6. The cup lid opening and closing protection circuit according to claim 2, characterized in that, The protection circuit also includes a first diode and a second diode; The positive terminal of the first diode is connected to the first branch, and the negative terminal of the first diode is connected to the positive terminal of the first energy storage module and the power supply terminal of the variable frequency motor drive module. The positive terminal of the second diode is connected to the second branch, and the negative terminal of the second diode is connected to the positive terminal of the second energy storage module and the input terminal of the level conversion module.

7. The cup lid opening and closing protection circuit according to claim 1, characterized in that, The level conversion module includes a transient voltage suppression diode, an N-type transistor, a P-type transistor, a second resistor, a third resistor, and a fourth resistor. The negative terminal of the transient voltage suppression diode is connected to the second branch, and the positive terminal of the transient voltage suppression diode is connected to the base of the N-type transistor through the second resistor. The base of the N-type transistor is also grounded through the third resistor. The emitter of the N-type transistor is grounded, and the collector of the N-type transistor is coupled to the base of the P-type transistor. The emitter of the P-type transistor is connected to a first voltage terminal, and the collector is coupled to the detection terminal of the main control module. The collector of the P-type transistor is also grounded through the fourth resistor.

8. The cup lid opening and closing protection circuit according to claim 7, characterized in that, The resistance of the second resistor is A2, and the resistance of the third resistor is A3, where A3 ≥ P. A2, P≥5.

9. The cup lid opening and closing protection circuit according to claim 7, characterized in that, The reverse breakdown voltage of the transient voltage suppression diode is U1, 10V≤U1≤14V, and the output voltage of the switching power supply is 15V.

10. The cup lid opening and closing protection circuit according to claim 1, characterized in that, The switch module includes a first switch, which is a low-voltage switch.

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