PWM (Pulse Width Modulation) control circuit and kitchen appliance

Abstract

The utility model provides a PWM (Pulse Width Modulation) control circuit and a kitchen appliance, which are arranged on first equipment and comprise an MCU (Microprogrammed Control Unit) used for generating a PWM control signal; the PWM output circuit is connected with the MCU and outputs a PWM wave for driving a load based on the PWM control signal; the protection circuit is connected with the PWM output circuit, and when the protection circuit works, the PWM output circuit is closed; the linked switch is linked with the working state of the second equipment and is used for controlling whether the protection circuit works or not; and the state acquisition circuit is connected with the MCU and is used for acquiring the state of the linked switch, the MCU generates a PWM control signal when detecting that the state of the linked switch is that the control protection circuit does not work, and the MCU stops generating the PWM control signal when detecting that the state of the linked switch is that the control protection circuit works.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kitchen appliance, especially a PWM control circuit and kitchen appliance. BACKGROUND

[0002] In the prior art, with the increasing functional requirements of kitchen appliances, most kitchen devices are equipped with MCU controllers to complete the functional control. In some kitchen appliances, multiple devices are linked to control, for example, when device 1 is turned on, device 2 will start, and when device 1 is turned off, device 2 will start. Generally, the more complex the MCU is, the more faults it has, such as overheating and downtime. When the MCU encounters downtime, the output control will be in an abnormal state, resulting in abnormal function and reducing user experience.

[0003] Taking a stove and a smoke machine (an oil smoke extractor) as an example, the logic of the linkage between the two is that the stove starts the smoke machine, and the stove is turned off while the smoke machine is turned off. However, in special cases, the smoke machine processor cannot detect the linkage signal due to downtime, resulting in the control signal of the smoke machine not being turned off, and the user experiences that the smoke machine does not close according to the normal function, thereby feeling abnormal. SUMMARY

[0004] The utility model provides a PWM control circuit and kitchen appliance to solve the problem that the MCU downtime in the prior art easily leads to the PWM control circuit being controlled incorrectly, resulting in abnormal state of the device.

[0005] The utility model provides a PWM control circuit, which is arranged in a first device and comprises:

[0006] An MCU for generating a PWM control signal;

[0007] A PWM output circuit connected with the MCU and outputting a PWM wave for driving a load based on the PWM control signal;

[0008] A protection circuit connected with the PWM output circuit, which is used to turn off the PWM output circuit when working;

[0009] A linkage switch linked with the working state of a second device, which is used to control whether the protection circuit works or not;

[0010] A state acquisition circuit connected with the MCU, which is used to acquire the state of the linkage switch. When the MCU detects that the state of the linkage switch is to control the protection circuit not to work, it generates a PWM control signal. When the MCU detects that the state of the linkage switch is to control the protection circuit to work, it stops generating a PWM control signal.

[0011] In some embodiments, the PWM output circuit specifically comprises:

[0012] comprises a control unit and an output unit;

[0013] The control unit drives the output unit switch based on the MCU PWM control signal to output the PWM wave driving the load.

[0014] In some embodiments, the control unit comprises:

[0015] resistor R12, resistor R13 and transistor Q4, the transistor Q4 is an NPN transistor;

[0016] The base of the transistor Q4 is connected to the pin of the MCU output PWM control signal through the resistor R12;

[0017] The base of the transistor Q4 is connected to the emitter of the transistor Q4 through the resistor R13 and grounded;

[0018] The collector of the transistor Q4 is connected to the control end of the output unit.

[0019] In some embodiments, the output unit comprises:

[0020] resistor R2, resistor R7, resistor R10, inductor L1, transistor Q1, the transistor Q1 is a PNP transistor;

[0021] The emitter of the transistor Q1 is connected to the power supply VCC1 through the resistor R2;

[0022] The collector of the transistor Q1 is connected to the load end through the inductor L1;

[0023] The collector of the transistor Q1 is grounded through the resistor R10;

[0024] The emitter of the transistor Q1 is connected to the base of the transistor Q1 through the resistor R7, and the base of the transistor Q1 is connected to the collector of the transistor Q4 as the control end of the output unit.

[0025] In some embodiments, the protection circuit comprises:

[0026] resistor R4, resistor R6, resistor R9, resistor R15, resistor R16, resistor R17, transistor Q2 and transistor Q5, the transistor Q2 and the transistor Q5 are both NPN transistors;

[0027] The base of the transistor Q5 is connected to the first end of the linkage switch through the resistor R15 and the resistor R16, and the second end of the linkage switch is connected to the power supply VCC1;

[0028] The base of the transistor Q5 is connected to the emitter of the transistor Q5 through the resistor R17 and grounded;

[0029] The collector of the transistor Q5 is connected to the base of the transistor Q2 through the resistor R9;

[0030] The emitter of the transistor Q2 is grounded;

[0031] The base of the transistor Q2 is connected to the power supply VCC2 through the point-in R6;

[0032] The collector of the transistor Q2 is connected to the output unit through the resistor R4, so as to close the output unit when the protection circuit starts protection.

[0033] In some embodiments, the collector of the transistor Q2 is connected to the emitter of the transistor Q1 of the output unit.

[0034] In some embodiments, the state acquisition circuit specifically comprises:

[0035] The resistor R1, the resistor R5 and the transistor Q3, wherein the transistor Q3 is an NPN transistor;

[0036] The collector of the transistor Q3 is connected to the sampling pin of the MCU;

[0037] The collector of the transistor Q3 is connected to the power supply VCC2 through the resistor R1;

[0038] The base of the transistor Q3 is connected to the power supply VCC2 through the resistor R5;

[0039] The base of the transistor Q3 is connected to the collector of the transistor Q5.

[0040] In some embodiments, the linkage switch is controlled by the wireless signal of the second device.

[0041] In some embodiments, the first device is a hood, and the second device is an induction cooker.

[0042] The utility model provides a kind of kitchen appliance, the kitchen appliance, including PWM control circuit.

[0043] Beneficial effects: by being provided with linkage switch of the working state linkage of second device in the PWM control circuit of first device and protection circuit, MCU can detect the state of linkage switch by state acquisition circuit, to control PWM wave output of PWM output circuit in normal state, when linkage switch is disconnected, if MCU is encountered downtime, MCU cannot detect the closing signal, by protection circuit, PWM output circuit can be closed, the function of hardware switch is played, so as to avoid that user perceives hood anomaly, optimize user experience. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0045] Figure 1 This is a circuit module block diagram of an embodiment of this application;

[0046] Figure 2 This is a circuit schematic provided in the embodiments of this application. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0048] It should be noted that, in the description of this application, the terms "comprising," "including," or any other variations thereof are intended to cover a 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. Unless otherwise specified, 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. The terms "upper," "lower," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0049] The terms "first", "second", and the like in this application are used to distinguish similar objects, and are not used to describe a particular order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of a kind and do not limit the number of objects, for example, the first object can be one or more. In addition, "and / or" means at least one of the connected objects, and " / " generally means that the front and rear associated objects are in a "or" relationship.

[0050] Reference Figure 1 A PWM control circuit, the PWM control circuit, is provided in a first device. In this embodiment, the PWM control circuit is used to output a PWM wave to control a load unit such as a motor, a heating device, a light, etc. While the first device can be, for example, a range hood, an induction cooker, a kitchen lamp, an exhaust fan, a microwave oven, etc. These devices can be linked to a second device through wired or wireless means in terms of their working state, and the second device can also be a device type listed for the first device. The first device and the second device can be a combination commonly used together. For example, the combination of a stove (gas stove, induction cooker, etc.) and a range hood. It can be understood that the linkage between the two can be a partial function linkage. For example, after the stove is started, the range hood turns on the light; after the stove is started, the range hood starts to exhaust. For example, this combination can also be a kettle and an exhaust fan, and after the kettle is started, the exhaust fan is also started. The above combinations cannot be exhausted and are only illustrative.

[0051] This embodiment takes the first device as a range hood and the second device as an induction cooker for illustration.

[0052] Comprising:

[0053] MCU, for generating a PWM control signal, the PWM control signal being used to drive the exhaust device of the range hood to work. Specifically, the exhaust device controls the exhaust intensity according to the duty cycle of the PWM signal.

[0054] PWM output circuit, connected with the MCU, outputs a PWM wave for driving the load based on the PWM control signal. In this embodiment, the voltage used by the MCU is low and cannot directly drive a load such as a motor with a higher voltage, so it is necessary to output a PWM wave with a high voltage by controlling the PWM output circuit.

[0055] Protection circuit, the protection circuit is connected with the PWM output circuit, and the protection circuit is closed when working. Generally, the PWM wave output can be controlled by a switch tube, and by pulling down the voltage of part of the pins of the switch tube, the switch tube pins can be made to not meet the opening voltage, thereby realizing the closing of the PWM circuit.

[0056] A linkage switch linked with the working state of the second device, the linkage switch being used to control whether the protection circuit works or not. In the embodiment, the linkage switch includes two states of opening and closing. When the linkage switch is closed, the protection circuit is in a non-working state. When the linkage switch is opened, the protection circuit enters a working state. The protection circuit will cut off the output of the PWM output circuit.

[0057] A state acquisition circuit connected with the MCU, used to acquire the state of the linkage switch. The MCU generates a PWM control signal when detecting that the state of the linkage switch is to control the protection circuit not to work. The MCU stops generating the PWM control signal when detecting that the state of the linkage switch is to control the protection circuit to work.

[0058] In the embodiment, the state of the linkage switch can be determined through a state acquisition circuit. Since the linkage switch has only two states, the state of the linkage switch can be determined through a pin of the MCU by detecting the level. Of course, the state can also be determined by voltage sampling through an ADC pin. Therefore, the MCU can perceive the working state of the linkage switch through the state acquisition circuit, so as to determine whether to output the PWM control signal.

[0059] The following will be combined with Figure 2 to provide a specific example to explain the design of the whole circuit.

[0060] The PWM output circuit specifically includes:

[0061] including a control unit and an output unit;

[0062] The control unit drives the output unit switch based on the PWM control signal of the MCU, to output the PWM wave for driving the load.

[0063] Specifically, the control unit includes:

[0064] a resistor R12, a resistor R13 and a transistor Q4, the transistor Q4 being an NPN transistor;

[0065] The base of the transistor Q4 is connected to the pin of the MCU outputting the PWM control signal through the resistor R12. The base of the transistor Q4 is connected to the emitter of the transistor Q4 through the resistor R13 and grounded. The collector of the transistor Q4 is connected to the control end of the output unit. The resistor R11 can be arranged on the transistor Q4, and the transistor Q4 is connected to the output unit through the resistor R11.

[0066] Specifically, the output unit includes:

[0067] Resistor R2 (resistance value can also be adjusted by parallel resistor R3), resistor R7, resistor R10, inductor L1, triode Q1, which is a PNP triode.

[0068] The emitter of the triode Q1 is connected to power supply VCC1 through the resistor R2. The collector of the triode Q1 is connected to the load end through the inductor L1. The collector of the triode Q1 is grounded through the resistor R10. The emitter of the triode Q1 is connected to the base of the triode Q1 through the resistor R7, and the base of the triode Q1 is connected to the collector of the triode Q4 as the control end of the output unit.

[0069] From Figure 2 the analysis, the working principle of the PWM output circuit is that the MCU controls the on-off of the triode Q4 through the output PWM control signal, the triode Q4 is closed when the MCU outputs low level, and the emitter of the triode Q1 is pulled high by VCC1. When the MCU outputs high level, the triode Q4 is opened, and the base of the triode Q1 is pulled low at this time, so that the triode Q1 is in the open state. Therefore, the MCU can control the PWM output circuit to generate PWM wave through the output level, and then control the load in the rear stage.

[0070] In some embodiments, the protection circuit comprises:

[0071] Resistor R4, resistor R6, resistor R9, resistor R15 (R16 is connected in series in this embodiment to adjust the resistance value), resistor R17, triode Q2 and triode Q5, both of which are NPN triodes;

[0072] The base of the triode Q5 is connected to the first end of the linkage switch through the resistor R15, and the second end of the linkage switch is connected to the power supply VCC1. The base of the triode Q5 is connected to the emitter of the triode Q5 and grounded through the resistor R17. The collector of the triode Q5 is connected to the base of the triode Q2 through the resistor R9. The emitter of the triode Q2 is grounded. The base of the triode Q2 is connected to the power supply VCC2 through the point-in R6. The collector of the triode Q2 is connected to the output unit through the resistor R4, so as to close the output unit when the protection circuit starts protection. The collector of the triode Q2 is connected to the emitter of the triode Q1 of the output unit.

[0073] From Figure 2The working of the protection circuit can be analyzed. In the embodiment, VCC2 (with filter capacitor C1) is generally a lower voltage than VCC1 (both are DC). Since VCC2 is mainly used to provide voltage to the control unit, a voltage of 3.3 to 5V is generally used. VCC1 needs to drive the load in the subsequent stage, and the voltage can be 12V or above. However, the specific voltage value needs to be determined according to the design of the electrical appliance, and the embodiment is only an example. It can be understood that when the linkage switch is closed, the triode Q5 is in an open state, which pulls down the base voltage of the triode Q2, causing Q2 to be closed. At this time, it is equivalent to that the entire protection circuit does not work, that is, it does not have any substantial effect on the PWM output circuit. When the linkage switch is opened, the triode Q5 is in a non-conducting state, at this time, the base of the triode Q2 is pulled up, so that the triode Q2 is turned on, which will pull down the voltage of the emitter of the triode Q1, causing the triode Q1 to be turned off.

[0074] In the embodiment, the state acquisition circuit specifically comprises:

[0075] The resistance R1, the resistance R5 and the triode Q3, wherein the triode Q3 is an NPN triode;

[0076] The collector of the triode Q3 is connected to the sampling pin of the MCU; the collector of the triode Q3 is connected to the power supply VCC2 through the resistance R1; the base of the triode Q3 is connected to the power supply VCC2 through the resistance R5; the base of the triode Q3 is connected to the collector of the triode Q5. In the embodiment, the triode Q3 is connected to the collector of the triode Q5 through the resistance R8.

[0077] From the acquisition circuit, the state of the linkage switch is determined by acquiring the level state of the collector of the triode Q5. When the linkage switch is in a closed state, the triode Q5 is open, so the collector is pulled down. At this time, the base of the triode Q3 is also pulled down, so the triode Q3 is not conductive, and the voltage (level) acquired by the MCU is close to VCC2 (equivalent to high level). Conversely, if the linkage switch is opened, the triode Q5 is cut off, which has no substantial effect on the circuit, and the triode Q3 is turned on. At this time, the voltage acquired by the MCU is close to ground. In this way, the state acquisition circuit can acquire the state of the linkage switch.

[0078] It can be understood that the MCU determines whether to output the PWM control signal based on the state of the linkage switch. Generally, the closed linkage switch indicates that the induction cooker (the second device) starts to work, and the smoke machine needs to start to work. When the MCU detects the corresponding signal, it starts to output the PWM control signal to drive the smoke extraction unit of the smoke machine to operate. The specific speed is adjusted according to the user's setting of the pulse width and duty cycle of the PWM wave, which is not discussed in detail in the present application, but it does not mean that the device using the present application only supports a single non-adjustable PWM wave output. When the smoke machine is working, under normal conditions, when the user turns off the induction cooker, the smoke machine will receive the signal and then turn off the linkage switch synchronously. At this time, the MCU should stop outputting the PWM control signal. However, in a special case, if the MCU is down during this process, it cannot detect the signal of the linkage switch. Therefore, if the MCU continues to output the PWM control signal during the downtime, or is always in a low control level, the triode Q1 will be in an always-on state. For users, they will observe that the induction cooker is turned off, but the smoke machine does not follow the off state, and they will feel abnormal. However, if the present embodiment is adopted, because of the existence of the protection circuit, even if the MCU cannot detect that the switch has been disconnected, the protection circuit will pull down the emitter level of the triode Q1, so that the triode Q1 is cut off and cannot output, thereby playing a role in hardware protection.

[0079] In some embodiments, the linkage switch is controlled by a wireless signal of the second device. Generally, the two devices communicate through a 433Mhz communication module, and the device state is indicated through the linkage switch. It can be understood that the linkage switch can be a relay, a switch tube or other controlled switch.

[0080] In some embodiments, the first device is a smoke machine, and the second device is an induction cooker.

[0081] The device embodiments described above are only schematic, and the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place, or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the present embodiment scheme according to actual needs. Those skilled in the art can understand and implement it without creative labor.

[0082] Those skilled in the art can clearly understand the implementation of the various embodiments by means of software and necessary general hardware platforms through the description of the above embodiments, and of course, the embodiments can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that makes a contribution, can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in the various embodiments or some parts of the embodiments.

[0083] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical code features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A PWM control circuit, characterized by comprising: The device is configured in the first device and includes: MCU is used to generate PWM control signals; The PWM output circuit is connected to the MCU and outputs a PWM wave to drive the load based on the PWM control signal. A protection circuit is connected to the PWM output circuit. When the protection circuit is working, it shuts down the PWM output circuit. A linkage switch that is linked to the working status of the second device, the linkage switch being used to control whether the protection circuit is working; A status acquisition circuit is connected to an MCU to acquire the status of the linkage switch. When the MCU detects that the linkage switch is in a state where the control protection circuit is not working, it generates a PWM control signal. When the MCU detects that the linkage switch is in a state where the control protection circuit is working, it stops generating the PWM control signal.

2. The PWM control circuit of claim 1, wherein, The PWM output circuit specifically includes: Includes a control unit and an output unit; The control unit drives the output unit switch based on the PWM control signal of the MCU to output a PWM wave that drives the load.

3. The PWM control circuit of claim 2, wherein, The control unit includes: Resistors R12 and R13 and transistor Q4, wherein transistor Q4 is an NPN transistor; The base of transistor Q4 is connected to the pin of the MCU that outputs the PWM control signal through resistor R12; The base of transistor Q4 is connected to the emitter of transistor Q4 through resistor R13 and grounded; The collector of the transistor Q4 is connected to the control terminal of the output unit.

4. The PWM control circuit of claim 2, wherein, The output unit includes: Resistor R2, resistor R7, resistor R10, inductor L1, transistor Q1, wherein transistor Q1 is a PNP transistor; The emitter of the transistor Q1 is connected to the power supply VCC1 through the resistor R2; The collector of transistor Q1 is connected to the load terminal through inductor L1; The collector of transistor Q1 is grounded through resistor R10; The emitter of transistor Q1 is connected to the base of transistor Q1 through resistor R7, and the base of transistor Q1 is connected to the collector of transistor Q4 as the control terminal of the output unit.

5. The PWM control circuit according to claim 2 or 4, characterized by The protection circuit includes: Resistors R4, R6, R9, R15, R16, R17, transistors Q2 and Q5, wherein transistors Q2 and Q5 are both NPN transistors; The base of the transistor Q5 is connected to the first terminal of the linkage switch through resistors R15 and R16, and the second terminal of the linkage switch is connected to the power supply VCC1. The base of transistor Q5 is connected to the emitter of transistor Q5 through resistor R17 and grounded; The collector of transistor Q5 is connected to the base of transistor Q2 through resistor R9; The emitter of transistor Q2 is grounded; The base of transistor Q2 is connected to power supply VCC2 via R6. The collector of transistor Q2 is connected to the output unit through resistor R4 to shut down the output unit when the protection circuit is activated.

6. The PWM control circuit of claim 5, wherein, The collector of transistor Q2 is connected to the emitter of transistor Q1 in the output unit.

7. The PWM control circuit of claim 5, wherein, The status acquisition circuit specifically includes: Resistors R1 and R5 and transistor Q3, wherein transistor Q3 is an NPN transistor; The collector of the transistor Q3 is connected to the sampling pin of the MCU; The collector of the transistor Q3 is connected to the power supply VCC2 through the resistor R1; The base of the transistor Q3 is connected to the power supply VCC2 through the resistor R5; The base of the transistor Q3 is connected to the collector of the transistor Q5.

8. The PWM control circuit of claim 1, wherein, The linkage switch is controlled by the wireless signal of the second device.

9. The PWM control circuit of claim 1, wherein, The first device is a smoke machine, and the second device is an electromagnetic oven.

10. A kitchen appliance characterized in that, The PWM control circuit as claimed in any one of claims 1-8. The PWM control circuit as claimed in any one of claims 1-8.

Images