Range hood control method and range hood

Abstract

The present invention relates to a control method for a range hood. The method comprises the following steps: 1. Presetting motor speeds under different currents, with speeds greater than V0 being designated as high speed zones, and vice versa as medium and low speed zones; presetting back electromotive force values of the motor at various speeds; 2. Determining whether the current actual motor operating speed V1 is greater than V0; if so, proceeding to step 3; if not, proceeding to step 4; 3. Obtaining the current motor back electromotive force value dV2 and the current motor back electromotive force value dV1 of the actual motor operating speed; determining whether dV2 is greater than dV1; if so, reducing the current motor back electromotive force value; if not, maintaining the current motor operating state; and 4. Obtaining the current motor back electromotive force value dV3; determining whether dV3 is greater than dV1; if so, increasing the current motor back electromotive force value; if not, maintaining the current motor operating state. A range hood is also disclosed.

Description

Technical Field

[0001] The present invention relates to the technical field of oil fume purification, and in particular to a control method for a range hood and the range hood. Background Art

[0002] A range hood is a kitchen appliance that purifies the kitchen environment. It operates based on the principles of fluid dynamics, using a centrifugal fan installed inside the range hood to draw in and exhaust cooking fumes. A centrifugal fan consists of a volute, an impeller mounted within the volute, and a motor that drives the impeller. As the impeller rotates, negative pressure is generated at the fan's center, drawing cooking fumes from beneath the range hood into the fan. After being accelerated by the fan, the fumes are collected by the volute and directed outside.

[0003] The motor is the power source of the range hood. When the resistance of the flue is large, the wind pressure of the range hood is insufficient, which can easily cause oil smoke to flow back. When cooking, the range hood has poor adaptability, low working air volume and efficiency, and unsatisfactory oil smoke extraction effect, which seriously affects the user experience.

[0004] In order to resist the exhaust capacity of the pipeline and prevent the occurrence of oil fume backflow in a complex load environment, a Chinese invention patent with application number CN202111357744.5 (application publication number CN114123884A) discloses a control method and control system for a range hood. The method includes: after the range hood is started, the drive motor in the range hood is controlled to operate in a constant torque mode, and the speed value, output current value and back electromotive force value of the drive motor are obtained in real time; when the speed value is greater than the base speed value of the drive motor and the output current value and back electromotive force value meet the preset conditions, the drive motor is subjected to weak magnetic control to increase the speed of the drive motor to the target speed value.

[0005] The greater the air volume of a range hood, the better the fume extraction effect, and the greater the air pressure, the faster the fume exhaust. Therefore, range hoods with high air pressure and air volume are more popular with users. However, the maximum air pressure and maximum air volume operating conditions are two contradictory points for motor characteristics. Both air pressure and air volume are related to the motor speed, torque, and power. The changes that affect the motor speed and torque are controlled by its back EMF. The motor's back EMF is an important parameter that acts as a current limiter during motor operation. It is positively correlated with the speed, and its volatility can directly lead to unstable motor performance. Therefore, timely compensation for the back EMF under various operating conditions is extremely important. However, if the motor's back EMF is too large, it can increase power but suppress speed, thereby increasing air volume and reducing air pressure. If the motor's back EMF is too small, it can increase speed but reduce power, thereby increasing air pressure and reducing air volume. It is often difficult to achieve both at the expense of one and the other. Since the above control method only allows the range hood to quickly reach the maximum static pressure after startup, it is not suitable for air volume requirements. Therefore, further improvement is needed to the existing range hood control method. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to provide a control method for a range hood that can meet the wind pressure and air volume requirements under different working conditions in response to the above-mentioned existing technology.

[0007] The second technical problem to be solved by the present invention is to provide a range hood to which the above range hood control method is applied.

[0008] The technical solution adopted by the present invention to solve the first technical problem is: a control method for a range hood, characterized by comprising the following steps:

[0009] Step 1: Preset the motor speed at different currents, and record the speed greater than the threshold V0 as the high speed zone, and the speed less than or equal to the threshold V0 as the medium and low speed zone; and preset the back electromotive force value of the motor at each speed;

[0010] Step 2: After the range hood has been running for T1 time, obtain the actual operating speed V1 of the current motor and determine whether V1 is greater than V0. If so, the current motor is actually running in the high speed range and the process proceeds to step 3; if not, the current motor is actually running in the medium-low speed range and the process proceeds to step 4; wherein T1>0;

[0011] Step 3: After the range hood has been operating for T2 time, where T2>T1, obtain the current motor back-electromotive force value dV2 and the current motor back-electromotive force value dV1 at the actual operating speed V1, and determine whether dV2 is greater than dV1. If so, reduce the current motor back-electromotive force value and proceed to step 2; if not, keep the motor in the current operating state;

[0012] Step 4: After the range hood has been operating for T3 time, where T3>T1, obtain the current motor back electromotive force value dV3 and the current motor back electromotive force value dV1 at the actual operating speed V1, and determine whether dV3 is greater than dV1. If so, the motor maintains the current operating state; if not, increase the current motor back electromotive force value and proceed to step 2.

[0013] In order to obtain the back electromotive force value of each motor at each speed, the specific steps of presetting the back electromotive force value of the motor at each speed in step 1 are as follows:

[0014] The back electromotive force value of the motor at any speed is preset, and the back electromotive force value at each speed is obtained based on the positive correlation coefficient between the speed and the back electromotive force value.

[0015] In order to avoid misjudgment, the judgment process in step 2, step 3 and step 4 is repeated at least twice, and it is judged whether the number of times the judgment result in each step is wrong is less than the corresponding fault tolerance value. If so, it means that the judgment result of the judgment process in the current step is correct; if not, it means that the judgment result of the judgment process in the current step is incorrect; wherein the fault tolerance value of the judgment result in each step is less than the number of repeated executions.

[0016] The present invention solves the second technical problem by adopting a technical solution: a range hood to which the above range hood control method is applied, comprising a fan system, wherein the fan system comprises an impeller and a motor for driving the impeller to rotate, and is characterized in that the range hood further comprises:

[0017] Speed detection module, used to detect the speed of the motor;

[0018] Back electromotive force detection module, used to detect the back electromotive force of the motor;

[0019] Three-phase windings with different numbers of turns are connected in series with the motor;

[0020] The controller is connected to the speed detection module, the back electromotive force detection module and the three-phase winding, and is configured to control the adjustment of the number of turns of the three-phase winding according to the detection results of the speed detection module and the back electromotive force detection module, thereby adjusting the back electromotive force of the motor.

[0021] In order to achieve a change in the back electromotive force value of the motor by changing the three-phase winding, preferably, the three-phase winding has a primary side and a secondary side, and the primary side and the secondary side of the three-phase winding respectively have at least two connection ends.

[0022] Compared with the prior art, the advantages of the present invention are: by presetting the motor speed under different currents, and dividing the speed into a high-speed zone and a medium-low speed zone, the high-speed zone corresponds to the working condition where the range hood requires a larger wind pressure, and the medium-low speed zone corresponds to the working condition where the range hood requires a larger air volume; therefore, when the range hood is working, it is first determined whether the current motor is actually operating in the high-speed zone or the medium-low speed zone, and then the motor back electromotive force under the current working condition is compensated in time to obtain the required speed and torque requirements of the motor under different working conditions, further improving the working wind pressure, air volume and efficiency of the range hood, avoiding abnormal phenomena in the range hood during operation, improving the sensitivity and reliability of the range hood, making it safer and more energy-saving, and maximizing the oil fume extraction effect and adaptive control accuracy of the range hood. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flowchart of the control method of the range hood in the embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 As shown, the control method of the range hood in this embodiment includes the following steps:

[0026] Step 1: Preset the motor speed at different currents, and record the speed greater than the threshold V0 as the high speed zone, and the speed less than or equal to the threshold V0 as the medium and low speed zone; and preset the back electromotive force value of the motor at each speed;

[0027] In this embodiment, the specific steps of presetting the back electromotive force value at each motor speed are:

[0028] The back electromotive force value of the motor at any speed is preset, and the back electromotive force value at each speed is obtained based on the positive correlation coefficient between the speed and the back electromotive force value;

[0029] Step 2: After the range hood has been running for T1 time, obtain the actual operating speed V1 of the current motor and determine whether V1 is greater than V0. If so, the current motor is actually running in the high speed range and the process proceeds to step 3; if not, the current motor is actually running in the medium-low speed range and the process proceeds to step 4; wherein T1>0;

[0030] Step 3: After the range hood has been operating for T2 time, where T2>T1, obtain the current motor back-electromotive force value dV2 and the current motor back-electromotive force value dV1 at the actual operating speed V1, and determine whether dV2 is greater than dV1. If so, reduce the current motor back-electromotive force value and proceed to step 2; if not, keep the motor in the current operating state;

[0031] Step 4: After the range hood has been operating for T3 time, where T3>T1, obtain the current motor back electromotive force value dV3 and the current motor back electromotive force value dV1 at the actual operating speed V1, and determine whether dV3 is greater than dV1. If so, the motor maintains the current operating state; if not, increase the current motor back electromotive force value and proceed to step 2.

[0032] A range hood employing the aforementioned range hood control method comprises a fan system, a speed detection module, a back-EMF detection module, three-phase windings with varying numbers of turns, and a controller. The fan system includes an impeller and a motor that drives the impeller. The speed detection module is configured to detect the motor's speed; the back-EMF detection module is configured to detect the motor's back-EMF; the three-phase windings with varying numbers of turns are connected in series with the motor. The controller is connected to the speed detection module, the back-EMF detection module, and the three-phase windings and is configured to adjust the number of turns of the three-phase windings based on the detection results of the speed detection module and the back-EMF detection module, thereby adjusting the motor's back-EMF.

[0033] In this embodiment, the motor is connected in series with three-phase windings with different numbers of turns, specifically: the primary side and the secondary side of the three-phase winding respectively have at least two connection ends, so that the number of turns of the three-phase winding can be changed accordingly by connecting different connection ends of the primary side and the secondary side of the three-phase winding; therefore, the number of turns of the three-phase winding connected in series with the current motor is reduced, so that the three-phase winding with fewer turns connected in series with the current motor works, so as to achieve the reduction of the current motor back electromotive force value in step 3; conversely, the number of turns of the three-phase winding connected in series with the current motor is increased, so that the three-phase winding with more turns connected in series with the current motor works, so as to achieve the reduction of the current motor back electromotive force value in step 4.

[0034] In addition, the judgment processes in step 2, step 3 and step 4 are repeated at least twice, and it is judged whether the number of times the judgment results in each step are wrong is less than the corresponding fault tolerance value. If so, it means that the judgment result of the judgment process in the current step is correct; if not, it means that the judgment result of the judgment process in the current step is incorrect; the fault tolerance value of the judgment result in each step is less than the number of repeated executions.

[0035] In this embodiment, when it is determined based on the actual operating speed of the motor that the motor is currently operating in the high speed range, the high speed corresponds to a condition where the range hood requires a higher air pressure. Therefore, it is necessary to further confirm whether the range hood needs to increase the air pressure to meet the requirement. Therefore, the back electromotive force value in step 3 is judged. If dV2 is greater than dV1, it means that the motor back electromotive force is too high and the speed is limited, and cannot reach the preset requirement. At the same time, the range hood is in one or more of the following scenarios:

[0036] 1. When the oil stains accumulate over a long period of time, the air outlet of the range hood is blocked by the oil stains, or when the user just turns on the range hood and uses it, the fire damper has not yet opened and requires a larger static pressure to open it;

[0037] 2. When users on the lower floors of a high-rise building cook and use a public flue, the air pressure in the flue increases with the increase in the number of floors, and the exhaust pressure increases. In addition, if the air pressure of the range hood at home is lower than that of others, the valve is easily blocked, and the oil smoke cannot be exhausted, which is likely to cause oil smoke backflow. Therefore, the air pressure of the range hood needs to be higher;

[0038] The motor is controlled to connect a three-phase winding with fewer turns in series and switch operation, which can reduce the back electromotive force value under this working condition, thereby obtaining a higher speed and increasing the air pressure of the range hood.

[0039] When the actual motor speed determines that the motor is currently operating in the medium-low speed range, the medium-low speed corresponds to a condition where the range hood requires a large air volume. Therefore, it is necessary to further confirm whether the range hood needs to increase the air volume to meet the demand. Therefore, according to the back electromotive force value in step 4, if dV3 is less than dV1, it means that the motor back electromotive force is too low and the power is weakened, failing to meet the preset requirements. At the same time, the range hood is in one or more of the following scenarios:

[0040] 1. When cooking stir-fry or cooking on multiple stoves at the same time, the rising oil smoke is similar to a mushroom cloud. The oil smoke rises straight up from the pot port and then quickly mixes with the air, and the volume quickly increases. It is most difficult for the range hood to absorb the oil smoke, so a larger air volume is required to ensure a better oil smoke extraction effect.

[0041] 2. When the resistance of the flue increases or there is interference from side wind, for example, if the windows in the room are opened too much or too large, the wind is too strong, forming convection to blow away the oil smoke, and the range hood is not effective in extracting smoke. Therefore, a larger air volume is needed to gather the oil smoke and suck it into the cavity for discharge;

[0042] 3. When the power supply voltage is insufficient, the range hood's suction power becomes smaller, so a larger air volume is required;

[0043] 4. When the filter of the range hood is too dirty and affects the air inlet area, the suction force of the range hood becomes smaller, so a larger air volume is required; often during use, the air volume of the range hood will be lost due to external factors, so it is necessary to increase the motor power to compensate for the air volume. Under the same wire diameter winding, increasing the coil winding can increase the motor power; the electromotive force regulation module controls the three-phase winding with more turns of the motor and switches the operation, which can increase the back electromotive force value under this working condition to obtain greater power, increase the air volume of the range hood, enhance the suction force, and improve the oil fume extraction effect.

Claims

1. A control method for a range hood, characterized in that The steps include: Step 1: Preset the motor speed under different currents, and record the speed greater than the threshold V0 as the high speed zone, and the speed less than or equal to the threshold V0 as the medium and low speed zone; And preset the back electromotive force value of the motor at each speed; Step 2: After the range hood has been running for T1 time, obtain the actual operating speed V1 of the current motor and determine whether V1 is greater than V0. If so, the current motor is actually running in the high speed range and proceed to step 3; If not, the current motor is actually running in the medium and low speed range, and the process goes to step 4; Where T1>0; Step 3: After the range hood has been operating for T2 time, where T2>T1, obtain the current motor back-electromotive force value dV2 and the current motor back-electromotive force value dV1 at the actual operating speed V1, and determine whether dV2 is greater than dV1. If so, reduce the current motor back-electromotive force value and proceed to step 2; if not, keep the motor in the current operating state; Step 4: After the range hood has been operating for T3 time, where T3>T1, obtain the current motor back electromotive force value dV3 and the current motor back electromotive force value dV1 at the actual operating speed V1, and determine whether dV3 is greater than dV1. If so, the motor maintains the current operating state; if not, increase the current motor back electromotive force value and proceed to step 2.

2. The control method according to claim 1, wherein: The specific steps of presetting the back electromotive force value at each speed of the motor in step 1 are: The back electromotive force value of the motor at any speed is preset, and the back electromotive force value at each speed is obtained based on the positive correlation coefficient between the speed and the back electromotive force value.

3. The control method according to claim 1 or 2, characterized in that: The judgment process in step 2, step 3 and step 4 is repeated at least twice, and it is judged whether the number of times the judgment result in each step is wrong is less than the corresponding fault tolerance value. If so, it means that the judgment result of the judgment process in the current step is correct; if not, it means that the judgment result of the judgment process in the current step is incorrect; The error tolerance value of the judgment result in each step is less than the number of repeated executions.

4. A range hood using the range hood control method according to any one of claims 1 to 3, comprising a fan system, wherein the fan system comprises an impeller and a motor for driving the impeller to rotate, wherein: The range hood further comprises: Speed detection module, used to detect the speed of the motor; Back electromotive force detection module, used to detect the back electromotive force of the motor; Three-phase windings with different numbers of turns are connected in series with the motor; The controller is connected to the speed detection module, the back electromotive force detection module and the three-phase winding, and is configured to control the adjustment of the number of turns of the three-phase winding according to the detection results of the speed detection module and the back electromotive force detection module, thereby adjusting the back electromotive force of the motor.

5. The range hood according to claim 4, characterized in that: The three-phase winding has a primary side and a secondary side, and the primary side and the secondary side of the three-phase winding each have at least two connection ends.

Images