CN114520616A

CN114520616A - Control method of switched reluctance motor, food processor adopting control method and food processor control method

Info

Publication number: CN114520616A
Application number: CN202111307048.3A
Authority: CN
Inventors: 杜杉杉; 茅忠群; 诸永定
Original assignee: Ningbo Fotile Kitchen Ware Co Ltd
Current assignee: Ningbo Fotile Kitchen Ware Co Ltd
Priority date: 2020-11-20
Filing date: 2021-11-05
Publication date: 2022-05-20

Abstract

A control method of a switched reluctance motor is characterized by comprising the following steps: step one, starting a program and carrying out initialization setting; step two, starting a motor and rotating according to a set rotating direction; step three, the motor operates in a normal working mode; step four, judging whether the motor is locked, if so, executing step five; if not, returning to the third step; and step five, the motor rotates reversely according to a preset mode, and the step four is returned. The invention also discloses a food processor adopting the control method and a control method of the food processor. The invention has the advantages that: the upper limit of the torque increase is preset, so that the motor can slowly apply force when cooking food (cooking) meets resistance, the action of turning and frying the food left and right in the actual cooking process is simulated, the completeness of the food can be kept, and the motor is suitable for the cooking mode of the cooking machine.

Description

Control method of switched reluctance motor, food processor adopting control method and food processor control method

Technical Field

The invention relates to a switched reluctance motor, in particular to a control method of the switched reluctance motor under low-speed operation (such as a cooking mode) and a food processor applying the control method of the switched reluctance motor, and also relates to a working mode of the food processor adopting the control method of the switched reluctance motor.

Background

In recent years, with the improvement of living standard of people, various food processors enter daily life of people, the food processors work on the principle that a blade at the bottom of a stirring cup rotates at a high speed to repeatedly break food under the action of water flow, and the high-end food processors have the functions of frying and baking besides the function of breaking food.

The motor is the core part that determines product performance and quality of the food processor, and the switched reluctance motor is mostly adopted as a driving part in the food processor at present. The switched reluctance motor in the prior art is mainly used in high-rotating-speed occasions, such as high rotating speeds of about 10000rpm which are often required by a high-speed wall breaking machine, the rotor rotational inertia of the switched reluctance motor is small, and the magnitude and direction of phase turn torque can be changed when current is subjected to phase change every time, so that the system has good dynamic response; in the prior art, the switched reluctance motor is designed and improved in a plurality of ways under high-speed operation, but researches on the dynamic performance of the switched reluctance motor are less under the condition of ultra-low-speed operation such as cooking (the rotating speed range is 40-200rpm), and if the traditional motor is applied to a cooking machine and cannot intelligently sense food, the food is easily crushed during ultra-low-speed cooking, the integrity of the food cannot be ensured, and the cooking taste is further influenced.

The existing Chinese patent application with the application number of ZL201810472338.5, namely 'a novel ultra-low-speed high-torque switched reluctance motor', provides a novel ultra-low-speed high-torque switched reluctance motor, the design of a stator assembly and a rotor assembly is improved mainly from the aspect of mechanical structure in the patent, a magnetic circuit with a short distance can be formed by adopting the motor, and the purposes of improving torque and reducing rotating speed are achieved. However, the patent does not relate to how to realize the control method of the switched reluctance motor in the low-speed operation mode, and when the switched reluctance motor is operated in the cooking mode, once the switched reluctance motor is easily found to be stuck or continuously rotates to cause food to be smashed, the torque cannot be timely adjusted to realize intelligent automatic cooking. Therefore, in view of the above existing problems, how to improve the intelligence degree of the food processor in an ultra-low speed operation mode (such as cooking) is a problem to be solved at present, and further improvement on the existing switched reluctance motor is to be made.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide a method for controlling a switched reluctance motor, which can effectively avoid the motor from stalling or can smash food, in view of the above-mentioned current state of the art.

The invention provides a food processor adopting the control method of the switched reluctance motor to work.

The third technical problem to be solved by the invention is to provide a control method of the food processor adopting the control method of the switched reluctance motor.

The technical scheme adopted by the invention for solving the first technical problem is as follows: a control method of a switched reluctance motor is characterized by comprising the following steps:

step one, starting a program and carrying out initialization setting;

step two, starting a motor and rotating according to a set rotating direction;

step three, the motor operates in a normal working mode;

step four, judging whether the motor is locked, if so, executing step five; if not, returning to the third step;

and step five, reversely rotating the motor according to a preset mode, and returning to the step four.

When the motor is locked, the motor can be prevented from being stuck in a reverse rotation mode, and preferably, the preset mode in the step five may be: and (3) the motor firstly realizes reverse rotation according to the set reverse rotation angle or the set reverse rotation time, and then the motor restores the set rotation direction in the step two. That is, the motor is reversed at a certain angle or for a certain time and then is restored to the preset rotating direction.

Preferably, the set reverse angle is 15 ° to 90 °, preferably 30 °; the set inversion time is 20ms to 100ms, preferably 50 ms.

As another preferred mode, the preset mode in the step five may also be: the motor realizes reverse rotation in the direction opposite to the current rotation direction, and maintains the reverse rotation direction. In case the motor takes place the locked rotor promptly, just realize the antiport promptly, until the locked rotor takes place next time, the motor is the reversal again, analogizes in turn, does not resume preset direction of rotation after the motor reversal.

In order to avoid frequent reverse back-and-forth rotation of the motor, as a further preferable mode, if the motor is locked, the following steps are further provided between the fourth step and the fifth step: step 4-1, increasing motor torque by the motor, judging whether a preset condition is met, and if so, executing a step five; if not, returning to the fourth step. The motor is not immediately reversely rotated after the locked rotor occurs, but torque is firstly increased to continuously maintain the original rotating direction, and if the motor cannot be driven to continuously rotate, reverse control is realized, so that the locked rotor caused by interference can be effectively avoided, the motor can run more stably, and the noise caused by frequent reverse rotation switching can be reduced.

The increase of the motor torque can be realized in various manners in the prior art, and preferably, the increase of the motor torque can be realized in the following manners: increasing motor torque by increasing the duty cycle; or increasing the motor torque by increasing the current value; or by increasing the phase voltage of the windings. The increase of the duty ratio, the current and the phase voltage of the winding can indirectly increase the motor torque, and is various options for increasing the motor torque.

The preset condition for stopping increasing the motor torque can be realized by various prior art methods, and is determined by presetting various threshold values, preferably, the preset condition in the step 4-1 may be: the total increase amount of the motor torque reaches a set maximum increment value; or the total time for increasing the motor torque reaches the set maximum accumulated time length; or the current of the motor reaches a set maximum current value; or the number of cycles in the process of increasing the motor torque reaches the set accumulated number of cycles. The torque increase of the motor is not increased all the time without limit, and if the motor is still locked after a preset condition is reached, reverse rotation control needs to be realized.

In order to be able to cook and stir-fry different foods in a targeted manner, it is further preferred that the following steps are provided between step four and step 4-1: and 4-0, selecting a preset threshold value of the maximum increment of the motor torque according to the type of the food to be processed. The food type can be selected when the motor starts, and the proper torque maximum increment is adopted for different soft and hard mouthfeel of food, so that the food is prevented from being smashed, and the mouthfeel of food cooking is improved.

The motor torque increasing mode can be realized by various boosting modes in the prior art, and preferably, the motor torque can be gradually increased in a way that the torque is monotonically increased along with time, and preferably, the slow boosting of the torque is realized in a way of linear function or square function or exponential function, for example.

Preferably, the increase of the motor torque may be increased in a manner that the torque is increased in a time step increasing manner, for example, the torque is directly increased from a current value to a preset value in a step-like manner in a unit time.

Preferably, in the fifth step, the motor performs reverse rotation according to a preset mode and returns to the fourth step, and the method further includes the following steps: and 5-1, increasing the motor torque by the motor according to set conditions. I.e. the increase of the motor torque may also be performed after the motor is reversed. The set condition is that the total increase amount of the motor torque reaches a set maximum increment value; or the total time for increasing the motor torque reaches the set maximum accumulated time length; or the current of the motor reaches a set maximum current value.

Preferably, the increase in the motor torque is achieved by: increasing motor torque by increasing the duty cycle; or increasing the motor torque by increasing the current value; or by increasing the phase voltage of the windings.

Preferably, the increase in motor torque in step 5-1 is at the time of motor reversal or after reversal into position. The increase of the motor torque can be performed synchronously with the reverse rotation, or can be applied after the reverse rotation is in place.

Preferably, the setting condition in step 5-1 is that the motor increases the torque according to the set torque increase amount within a preset reverse rotation angle or reverse rotation time.

Preferably, the initialization setting in the first step includes setting a starting duty ratio D of the motor_startAnd the rotation direction, and the working rotation speed V of the motor is set.

Preferably, the start-up duty cycle D_startThe initial value range of (2) can be set to be 0.01-0.05, the duty ratio does not need to be large at the beginning, and only the motor can be ensured to rotate.

Preferably, the motor in the second step is started in an ultra-low speed operation mode, and the range of the operating speed V of the motor in the ultra-low speed operation mode is usually set to 40rpm to 200 rpm. The ultra-low speed rotating speed range is mainly aimed at a cooking mode of the food processor.

The determination method of the motor stalling can be implemented in various manners in the prior art, and preferably, the determination of whether the motor stalls in the fourth step is implemented by the following method: and setting a current threshold value or a torque threshold value or a rotating speed threshold value or a position signal threshold value when the motor is locked, and judging that the motor is locked once the current or the torque or the rotating speed or the position signal of the motor reaches or exceeds the set threshold value.

Preferably, the step four of judging whether the motor is locked up may specifically be implemented by:

step 4a, a timer times external interruption, the time is set to be T1, a position sensor detects the current position of the rotor, and a conducting winding is set;

step 4b, judging whether the timing time T1 of the timer is larger than the set maximum accumulated time T_setIf yes, judging that the motor is locked, and jumping out of the program; if not, executing the next step 4 c; wherein the maximum accumulated time T_setA window time length for waiting for an external interrupt to arrive;

step 4c, judging whether external interruption comes or not, if so, performing phase change on the set conduction winding, and returning to the step 4 a; if not, returning to the step 4 b.

When the external interruption is not present for a long time, it is necessary to slowly apply force to the motor (i.e. increase the torque), and preferably, the maximum cumulative time T_setSetting window time length for waiting external interrupt, the maximum accumulated time T_setThe value of (b) can be in the range of 60ms to 100ms, preferably 70 ms.

Preferably, in step 4b, after it is determined that the motor is locked, the following steps are continuously performed to realize the slow energization of the motor torque:

step 4D, outputting the duty ratio D in real time_rtN% increase every t milliseconds; wherein t and n are both preset constants;

step 4e, judging whether the timing time T1 of the timer is greater than T_set+T_incIf yes, the motor rotates in the direction opposite to the set rotating direction, the conducting windings are conducted to change phases according to the conducting sequence after the motor rotates reversely, meanwhile, the timing time T1 of the timer is cleared, and the step 4a is returned; if not, executing the step 4 c;

wherein, the

Represents the duty cycle from D₁To D₂The maximum increase time of; d₁Represents the duty ratio, D, corresponding to the detected current torque M of the motor₂Representing the duty ratio corresponding to the motor torque M plus delta M; Δ M is the maximum increase in torque within a predetermined angular interval of the position signal, and Δ D is the increase per millisecond of a predetermined duty cycle. The torque of the motor can be slowly increased by increasing the set duty ratio in unit time, and the motor is simple and convenient to operate and easy to realize.

Preferably, the value range of the increment delta D of the preset duty ratio per millisecond is 0.05% -0.2%. The increment delta D of the duty ratio per millisecond determines the stability of rotating speed regulation, when the delta D is too small, the motor is blocked and stops, and when the delta D is too large, the rotating speed is overshot, so that a proper value range needs to be set to ensure the stability and the continuity of the rotation of the motor.

When the motor runs at an ultra-low speed, in order to avoid food from being smashed, the increased torque cannot be too large, and meanwhile, a certain rotating torque needs to be ensured, and preferably, the value range of the maximum torque increase delta M is 0.01 Nm-0.05 Nm. The torque maximum increase Δ M is the torque maximum increase within a single step angle (15 ° in this embodiment) and is too small, resulting in the motor not being able to get too far into the food jam, and too large, resulting in the food being crushed.

Preferably, the value range of t in the step 4d is as follows: t is more than or equal to 0.5 and less than or equal to 5.

Preferably, the value range of n in the step 4d is: n is more than or equal to 0.05 and less than or equal to 0.2.

Preferably, for convenience of operation and control, the smooth rotation of the motor and the uniform force application are ensured, and in the step 4c, the set conducting winding phase commutation is realized through the following steps:

step 4c-1, judging whether the current rotation direction of the motor is consistent with the set rotation direction, if so, executing the next step 4 c-2; if not, jumping to the step 4 c-4;

step 4c-2, detecting and obtaining the actual time difference T of two adjacent external interrupts in real time_extiAnd calculating to obtain the current real-time rotating speed V of the motor_rtAdjusting the duty ratio to reach the preset working rotating speed V of the motor;

4c-3, conducting the windings, carrying out phase change according to the conducting sequence of the current motor rotating direction, clearing the timing time T1 of the timer, and returning to the step 4 a;

and 4c-4, rotating the motor in the direction opposite to the set rotating direction, carrying out phase change on the conducting winding according to the conducting sequence after the motor is reversed, namely, the motor does not need to be restored to be consistent with the preset rotating direction after being reversed, and simultaneously resetting the timing time T1 of the timer and returning to the step 4 a.

Preferably, a value angle of the preset position signal angle interval may be set as a motor step angle, and for the switched reluctance motor being a four-phase 8/6-level switched reluctance motor, the value of the motor step angle is 15 °. If the motor is an 6/4-level switched reluctance motor, the step angle is 30 degrees, and the value angle of the preset position signal angle interval can be 30 degrees.

The switched reluctance motor of the embodiment is a four-phase 8/6-level switched reluctance motor, and for the motor structure of the four-phase 8/6-level switched reluctance motor, correspondingly, the current position of a motor rotor is detected by a position sensor arranged on the motor, and the position sensor comprises a transmission-type sensor and a shutter disk; the transmission-type sensor is provided with two a + salient poles and two d-salient poles which are respectively arranged on the adjacent a + salient poles and d-salient poles on the stator, the shading disc is a disc arranged on the rotor shaft, the shading disc comprises a shading sheet structure which is matched with the salient poles of the rotor in quantity and section shape, and the shading sheet is perpendicular to the shading disc. If the switched reluctance motor with other structures is adopted, the arrangement mode of the position sensor needs to be changed correspondingly.

The technical scheme adopted by the invention for solving the second technical problem is as follows: the utility model provides a cooking machine, including switched reluctance motor, its characterized in that: the switched reluctance motor works by adopting the control method.

The technical scheme adopted by the invention for solving the third technical problem is as follows: the utility model provides a control method of cooking machine, cooking machine is including agitating unit and the switched reluctance motor that can drive this agitating unit work, its characterized in that, the mode of cooking machine is including preventing grinding the mode, and this cooking machine's control method includes: under preventing crushing mode, the cooking machine adopts control method control switch reluctance motor as above to rotate, and, switch reluctance motor drive agitating unit stir the food material in the cooking machine.

Compared with the prior art, the invention has the advantages that: by the characteristics that the switched reluctance motor can rotate forward and backward and has high reversing speed, the motor can be controlled to rotate reversely when food cooking (cooking) meets resistance, the action of cooking food left and right in the actual cooking process is simulated, and the motor is effectively prevented from rotating in a blocking way or being stuck; furthermore, by presetting an upper limit of torque increase (namely the maximum torque increase Delta M) or limiting the force application time, slow force application can be realized under the condition of motor stalling, once the upper limit of the torque increase is exceeded or the motor cannot normally rotate for a specified time, the motor is controlled to reversely rotate, and the control mode is not easy to crush food in the application of the motor ultra-low speed working mode, can keep the integrity of the food and is suitable for the frying mode of the food processor.

Drawings

Fig. 1 is a schematic diagram of an arrangement structure of a position sensor of a four-phase 8/6-level switched reluctance motor according to an embodiment of the present invention.

Fig. 2 is a torque characteristic diagram of a four-phase 8/6-level switched reluctance motor according to an embodiment of the present invention.

Fig. 3 is a diagram illustrating a four-phase winding null stabilizing characteristic of a four-phase 8/6-level switched reluctance motor according to an embodiment of the present invention.

Fig. 4 is a diagram of position signal and conducting winding characteristics (start-up phase) of a four-phase 8/6-level switched reluctance motor according to an embodiment of the present invention.

Fig. 5 is a block diagram illustrating a motor control method according to an embodiment of the present invention.

Fig. 6 is a second step block diagram of the motor control method according to the embodiment of the invention.

Fig. 7 is a flowchart illustrating an embodiment of a motor control method according to the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

The present embodiment uses a four-phase 8/6-stage switched reluctance motor, in which 8 is the number of stator stages and 6 is the number of rotor stages, and the motor has a step angle of 15 °.

As shown in fig. 1, the motor of the present embodiment includes a stator 1 and a rotor 2, the position of the rotor 2 is detected by a photosensitive rotor position sensor, the photosensitive rotor position sensor generally includes a transmission-type photoelectric sensor (including a photoelectric switch of an infrared transmitting tube and an infrared receiving tube) and a light shielding disc, and the structures of the transmission-type photoelectric sensor and the light shielding disc are both in the prior art;

the transmission type photoelectric sensor comprises two sensors S and two sensors P, wherein the two sensors are respectively arranged on two adjacent stator 1 salient poles (an + salient pole and a d-salient pole), the centers of the sensor S and the a + salient pole of the stator 1 are aligned, the centers of the sensor P and the d-salient pole of the stator 1 are aligned, and the included angle formed by the sensor S and the sensor P after connection with the center of the motor is 45 degrees; a groove is formed between the infrared transmitting tube and the infrared receiving tube of each sensor, the shading disc is a disc arranged on the rotor shaft and can rotate synchronously with the rotor 2, shading sheets 3 matched with the cross section shapes of the convex teeth are arranged on the shading disc along the circumference at the positions corresponding to the convex teeth of the rotor, the shading sheets 3 are arranged perpendicular to the disc surface of the shading disc (namely 6 shading sheets 3 are included on the shading disc and are uniformly distributed along the circumference), and the hatching of the shading sheets arranged vertically is shown in figure 1;

when the convex teeth of the rotor 2 rotate to the position where the sensor S, P is arranged, the shading sheet 3 just passes through the groove of the sensor, the light of the infrared emission tube is shaded to cut off the photosensitive transistor, and the output state is 0; when the groove of the rotor is rotated to the position of the sensor S, P, no light-shielding sheet passes through the groove of the sensor at this time, the light of the infrared emission tube is not shielded, the phototransistor is switched on, the output state is 1, and in one rotor angular period (namely 60 °), the sensor S and the sensor P can generate two square wave signals with the phase difference of 15 ° and the duty ratio of 50%, and the two square wave signals are combined into four different states which respectively correspond to different reference positions of the four-phase winding.

If the motor rotates clockwise, the middle point of the lowest inductance of the winding of the phase a is taken as 0 °, as shown in fig. 2, that is, the torque characteristics of the windings of the motor when the motor rotates clockwise are shown.

Two sensors S, P are used to detect the external interrupt signal, when the sensor S, P detects the abrupt change (i.e. jump), the motor enters the external interrupt, and the switch reluctance motor performs the phase change operation. For example, in the case of 50rpm, the time difference between the two external interruptions is 50ms, and during actual use, the rotation speed of the motor changes continuously along with the disturbance of the torque, so that the time difference between the two external interruptions in actual operation of the motor changes constantly.

As shown in fig. 3, a stable zero position for the A, B, C, D four-phase winding is shown. According to the minimum principle of the magnetic resistance of the switched reluctance motor, if a certain phase winding is excited by stable current, finally, the rotor is fixed at a stable zero position. If the two phase windings are energized with a steady current at the same time, the rotor will eventually also be held in the same steady position as in fig. 3.

For a four-phase 8/6-level switched reluctance motor, when equal currents are excited to the windings, a set of equal and different torque vectors is generated

Wherein at the torque vector

The A-phase winding generates a stable zero (fixed in this position) at the torque vector

The B-phase winding generates a stable null (fixed in this position) which is spatially at a geometrical angle of 15 °, i.e. at a step angle. If the windings are energized in the order of A → B → C → D, the rotor of the switched reluctance motor will be at a step angle of 15 DEG oneRotating step by step.

Considering that the torque of the switched reluctance motor is greatly changed when the switched reluctance motor is applied to the food processor, the torque is not known during starting, and two-phase starting is generally adopted in practice. In the starting process of the switched reluctance motor, in a rotor angle period of 0-60 degrees of rotor position, the electric sequence of each phase is AB → DA → CD → BC, which is similar to the double four-beat starting operation mode of a stepping motor. As shown in fig. 4, which is a characteristic diagram of the position signal and the conducting winding of the motor at the time of starting, the logical relationship between the position signal and the conducting phase (starting phase) of the motor is shown in table 1:

TABLE 1 Start-up phase commutation logic

Table 1 above illustrates the conducting windings corresponding to different position signals of the motor, for example, when the position signal P11 is detected, the conducting windings are in a phase a and a phase B; when the position signal P00 is detected, the conductive winding is in the C-phase and the D-phase.

In a cooking application scene, the requirement on the rotating speed is very low, and at the moment, certain nonlinearity exists in the output torque and the duty ratio. According to the traditional motor control method, when the motor is blocked, the torque can be increased all the time until the motor overcomes the resistance to continue rotating, or the motor is directly alarmed to be blocked, the control method is difficult to ensure the completeness of food in a cooking mode, the action of manually turning and cooking the food cannot be simulated, the final cooking effect is poor when the control method is applied to a food processor, the food made by the control method is different in quality, and the taste can be influenced.

In order to solve the above problem, as shown in fig. 5, the present embodiment proposes a control method of a switched reluctance motor, the control method including the steps of:

step one, starting a program and carrying out initialization setting;

step two, starting a motor and rotating according to a set rotating direction;

step three, the motor operates in a normal working mode;

and step five, the motor rotates reversely according to a preset mode, and the step four is returned.

The control method is to immediately make the motor rotate reversely when the motor is blocked so as to simulate stir-frying action and avoid food from being stuck. But in order to prevent the motor from frequently switching back and forth to rotate reversely, when the motor is blocked, a certain force can be applied to the motor firstly, the moment is slowly increased, and if the motor is still blocked, the motor is rotated reversely, so that the food can be prevented from being crushed. Therefore, the control method can add the step 4-1 when the motor is locked, and realize the process of gradually applying force.

Further, in order to better meet the requirements of different food materials and to specifically control the boost of different foods, the present embodiment may further increase the selection step of the maximum increment of the torque before step 4-1, and specifically, the control method of the switched reluctance motor of the present embodiment may include the following steps:

the method comprises the steps of firstly, starting a program, and carrying out initialization setting, wherein the initialization setting can comprise the step of setting the starting duty ratio D of a motor_startAnd the rotation direction, and setting the working rotation speed V of the motor; wherein the start-up duty ratio D_startThe value range of the initial value of (A) can be 0.01-0.05; the working speed V of the motor is set according to different working scenes of the motor, the motor of the embodiment is started in an ultra-low speed working mode, and the value range of the working speed V of the motor in the ultra-low speed working mode is 40rpm-200 rpm.

And step two, starting the motor and rotating according to the set rotating direction.

And step three, the motor operates in a normal working mode.

Step four, judging whether the motor is locked, if so, executing the step 4-0; if not, returning to the third step; the determination of whether the motor is locked is achieved in various ways in the prior art, and preferably can be achieved by the following method: and setting a current threshold value or a torque threshold value or a rotating speed threshold value or a position signal threshold value when the motor is locked, and judging that the motor is locked once the current or the torque or the rotating speed or the position signal of the motor reaches or exceeds the set threshold value.

And 4-0, selecting a preset threshold value of the maximum increment of the motor torque according to the type of the food to be processed.

Step 4-1, increasing motor torque by a motor, judging whether a preset condition is met, and if so, executing a step five; if not, returning to the fourth step.

The preset condition in step 4-1 can be implemented in various manners in the prior art, and preferably may be: the increment of the motor torque reaches a set maximum increment value; or the total time of the motor torque increase reaches the set maximum accumulated time length; or the current of the motor reaches a set maximum current value; or the number of cycles in the process of increasing the motor torque reaches the set accumulated number of cycles.

The increase of the motor torque can be realized by adopting the following various methods in the prior art: increasing motor torque by increasing the duty cycle; or increasing the motor torque by increasing the current value; or by increasing the phase voltage of the windings. The motor torque can be indirectly increased by increasing the duty ratio, the current and the winding phase voltage, and the motor torque can be slowly applied by increasing the preset values of the duty ratio, the current and the winding phase voltage in unit time.

In addition, the increase of the motor torque is not one step, the magnitude of each increase can be set, the gradual increase of the torque can be realized by means of slow force application, the gradual increase of the torque can be realized by means of various force application modes in the prior art, and preferably, each increase of the motor torque can be gradually increased in a way that the torque is monotonically increased along with time, such as a way that the torque is increased along with time by a linear function is adopted, or a way that the torque is increased along with time by a square function, or an exponential function way that the torque is increased along with time is adopted, so that the gradual increase of the torque is realized.

As a further preference, the increase in the motor torque can also be increased in incremental steps of torque over time, i.e. each time the torque increases stepwise from the current value directly to the preset value.

The various functions in the torque increasing mode are known in the art, and the torque increasing mode may be implemented by using other functions besides the above functions.

And step five, the motor rotates reversely according to a preset mode, and the step four is returned. Wherein, the preset mode in the step five may be: the motor firstly realizes reverse rotation according to a set reverse rotation angle or a set reverse rotation time, then the motor restores the set rotation direction in the step two, namely the motor firstly reverses and then restores the preset rotation direction, wherein the set reverse rotation angle is 15-90 degrees, and preferably 30 degrees; the set inversion time is 20 ms-100 ms, preferably 50 ms; the preset mode in the fifth step may also be: the motor realizes the reverse rotation according to the direction opposite to the current rotation direction, and maintains the direction of the reverse rotation, namely the motor maintains the rotation direction after the reverse rotation until the next locked-rotor happens. Above-mentioned two kinds of modes of predetermineeing can all realize simulating the artifical action of stir-fry that turns over, effectively avoid the cooking machine to be stuck in the condition that falls into by the card in the course of working.

As another preferable mode, as shown in fig. 6, in the fifth step, the motor performs reverse rotation according to a preset mode and returns to the fourth step, and the method further includes the following steps: and 5-1, increasing the motor torque by the motor according to set conditions. I.e. the increase of the motor torque may also be performed after the motor is reversed. The set condition is that the total increase amount of the motor torque reaches a set maximum increment value; or the total time for increasing the motor torque reaches the set maximum accumulated time length; or the current of the motor reaches a set maximum current value. The increase of the motor torque is realized by the following modes: increasing motor torque by increasing the duty cycle; or increasing the motor torque by increasing the current value; or by increasing the phase voltage of the windings.

Preferably, the increase in motor torque in step 5-1 is at the time of motor reversal or after reversal into position. The increase of the motor torque can be performed synchronously with the reverse rotation, and the force can be applied after the reverse rotation is in place; in the step 5-1, the condition is set that the motor increases the torque according to the set torque increment within the preset reverse rotation angle or reverse rotation time.

As shown in fig. 7, a more specific and detailed control flow diagram implemented by the step diagram of the control method shown in fig. 5 is provided, in the detailed control flow, the duty ratio is mainly used as an adjustment parameter, and the waiting time of the external interrupt is collected by using a timer in a timing manner, so that the operation is simple and convenient, the existing structure of the motor device is not required to be changed or added, the implementation is easy, the control cost is low, and specifically, the control method includes the following steps:

step 400, the program starts, and the starting duty ratio D of the motor is set_startA working speed V and a rotating direction; start duty cycle D_startThe value range of the initial value can be set to be 0.01-0.05, and the rotation direction can be clockwise or anticlockwise; the present embodiment is mainly directed to the cooking mode of the food processor, so the motor operates in the ultra-low speed operation mode, and the operating speed V of the motor is usually set to 40rpm to 200 rpm.

Step 401, the motor is started in an ultra low speed mode of operation.

step 4b, judging whether the timing time T1 of the timer is larger than the set maximum accumulated time T_setIf yes, judging that the motor is locked, and jumping to the step 4 d; if not, executing the next step 4 c;

when the external interruption is not over a long time, which indicates that the motor is blocked (such as the blade is blocked by food), the motor needs to be slowly forced (i.e. torque is increased), wherein the maximum accumulated time T is_setA window time length for waiting for an external interrupt to arrive; normally, the maximum accumulation time T is set_setPreferably, the value of (c) is in the range of 60ms to 100ms, and more preferably 70 ms.

Step 4c, judging whether external interruption comes or not, if so, executing step 4 c-1; if not, returning to the step 4 b.

Step 4D, outputting the duty ratio D in real time_rtN% increase every t milliseconds; wherein t and n are both preset constants, and the value range of t is as follows: t is more than or equal to 0.5 and less than or equal to 5, and the value range of n is as follows: n is more than or equal to 0.05 and less than or equal to 0.2.

Step 4e, judging whether the timing time T1 of the timer is greater than T_set+T_incIf yes, executing step 4 c-4; if not, executing the step 4 c;

wherein, the

Represents the duty cycle from D₁To D₂The maximum increase time of (c); d₁Representing the duty ratio corresponding to the current torque M of the motor obtained by detection, and the corresponding functional relation is D₁＝h(M)；D₂The duty ratio corresponding to the motor torque of M plus delta M is represented, and the corresponding functional relation is D₂H (M +. DELTA.M), the corresponding relation between torque and duty ratio belongs to the prior art, and one parameter value of the torque or the duty ratio is known, namely the other parameter value can be deduced reversely; Δ M is the maximum increase in torque within a preset position signal angle interval, and Δ D is the increase per millisecond of a preset duty cycle.

The switched reluctance motor of this embodiment is a four-phase 8/6-level switched reluctance motor, and the minimum value angle of the preset position signal angle interval can be selected as the motor step angle, that is, the value is 15 °. If the motor is an 6/4-level switched reluctance motor, the step angle is 30 degrees, and the minimum value angle of the preset position signal angle interval can be 30 degrees;

in the embodiment, the maximum torque increase Δ M is a maximum torque increase within a single step angle (i.e., 15 °), when the motor runs at an ultra-low speed, in order to avoid food being smashed, the increased torque cannot be too large, and if the value of the maximum torque increase is too small, the motor cannot be used when the food is stuck, and we select the following representative foods as examples in the experiment process, and the value of Δ M corresponding to each food is shown in table 2:

food category	△M(Nm)
		Spareribs	0.05
Pan wrapped meat	0.03
		Vegetarian chicken	0.02
Pickled Chinese cabbage fish	0.01

TABLE 2 maximum increase of torque for different foods

As can be seen, for the currently common cooking food materials, the value range of the maximum torque increase Δ M is preferably 0.01Nm to 0.05Nm, and is preferably 0.02 Nm; the value range can basically give consideration to stir-frying of harder food (such as bones) and softer and tender food (such as fish), and the food is prevented from being crushed in the stir-frying process.

In addition, the increment delta D of each millisecond of the preset duty ratio ranges from 0.05% to 0.2%, and the optimal value is 0.1%. The increment delta D of the duty ratio per millisecond determines the stability of rotating speed regulation, when the delta D is too small, the motor is blocked and stops, and when the delta D is too large, the rotating speed is overshot, so that a proper value range needs to be set to ensure the stability and the continuity of the rotation of the motor.

step 4c-2, detecting and obtaining the actual time difference T of two adjacent external interrupts in real time_extiAnd calculating to obtain the current real-time rotating speed V of the motor_rtAdjusting the duty ratio to reach the preset working rotating speed V of the motor; the adjustment of the duty cycle can be achieved using a known PI adjustment algorithm.

and 4c-4, rotating the motor in the direction opposite to the set rotating direction, conducting the windings, changing the phases according to the conducting sequence after the motor is reversed, clearing the timing time T1 of the timer, and returning to the step 4 a.

The control method of the embodiment comprises a soft start process of the motor, is simple and easy to implement, can prevent food from being smashed by slowly applying force and effectively controlling the time of phase change and reverse rotation of the motor in an ultra-low speed working mode (cooking mode) of the motor, realizes the action of simulating manual food stir-frying, and improves the intelligent operation level and cooking effect of the food processor.

In addition, this embodiment has still disclosed a cooking machine and control method thereof, this cooking machine is including agitating unit and switched reluctance motor, wherein, this cooking machine can select different mode according to eating material or the difference of culinary art mode at the during operation, mode is including preventing grinding the mode, should prevent grinding the mode under selecting, the switched reluctance motor of cooking machine adopts as above control method rotate and work, simultaneously, switched reluctance motor drives agitating unit and realizes the stirring to eating the material, prevent grinding the mode and can effectively prevent food card stifled at the cooking machine course, can also simulate artifical effect of stir-fry, avoid food to be stirred the bits of broken glass, make the culinary art effect better.

Claims

1. A control method of a switched reluctance motor is characterized by comprising the following steps:

step one, starting a program and carrying out initialization setting;

step two, starting a motor and rotating according to a set rotating direction;

step three, the motor operates in a normal working mode;

step five, the motor rotates reversely according to a preset mode, and the step four is returned;

wherein the preset mode in the fifth step is as follows: the motor firstly realizes reverse rotation according to the set reverse rotation angle or the set reverse rotation time, and then the motor recovers the set rotation direction in the step two; or, the preset mode in the fifth step is as follows: the motor realizes reverse rotation in the direction opposite to the current rotation direction, and maintains the reverse rotation direction.

2. The control method of the switched reluctance motor according to claim 1, wherein: the set reverse rotation angle is 15-90 degrees.

3. The control method of the switched reluctance motor of claim 1, wherein: the set inversion time is 20ms to 100 ms.

4. The control method of the switched reluctance motor according to claim 1, wherein: if the motor is locked, the following steps are also arranged between the fourth step and the fifth step:

step 4-1, increasing motor torque by the motor, judging whether a preset condition is met, and if so, executing a step five; if not, returning to the fourth step.

5. The control method of the switched reluctance motor according to claim 4, wherein: the preset conditions in the step 4-1 are as follows: the total increase amount of the motor torque reaches a set maximum increment value; or the total time for increasing the motor torque reaches the set maximum accumulated time length; or the current of the motor reaches a set maximum current value; or the number of cycles in the process of increasing the motor torque reaches the set accumulated number of cycles.

6. The control method of the switched reluctance motor according to claim 4, wherein: the increase of the motor torque is realized by the following modes: increasing motor torque by increasing the duty cycle; or increasing the motor torque by increasing the current value; or by increasing the phase voltage of the windings.

7. The control method of the switched reluctance motor according to claim 4, wherein: the increase in the motor torque gradually increases in such a manner that the torque monotonically increases with time.

8. The control method of the switched reluctance motor according to claim 7, wherein: the monotone increasing mode comprises a linear function mode or a square function mode or an exponential function mode.

9. The control method of the switched reluctance motor according to claim 4, wherein: the increase in the motor torque increases in torque steps with time.

10. The control method of the switched reluctance motor according to claim 4, wherein: the following steps can be further arranged between the fourth step and the step 4-1:

11. The control method of the switched reluctance motor according to claim 1, wherein: in the fifth step, the motor performs reverse rotation according to a preset mode and returns to the fourth step, and the method further comprises the following steps:

and 5-1, increasing the motor torque by the motor according to set conditions.

12. The control method of the switched reluctance motor according to claim 11, wherein: the increase in motor torque in step 5-1 is at the time of motor reversal or after reversal into position.

13. The control method of the switched reluctance motor according to claim 11, wherein: in the step 5-1, the condition is set that the motor increases the torque according to the set torque increment within the preset reverse rotation angle or reverse rotation time.

14. The control method of the switched reluctance motor according to claim 11, wherein: the set condition is that the total increase amount of the motor torque reaches a set maximum increment value; or the total time for increasing the motor torque reaches the set maximum accumulated time length; or the current of the motor reaches a set maximum current value.

15. The control method of the switched reluctance motor according to claim 11, wherein: the increase of the motor torque is realized by the following modes: increasing motor torque by increasing the duty cycle; or increasing the motor torque by increasing the current value; or by increasing the phase voltage of the windings.

16. The control method of the switched reluctance motor according to claim 1, wherein: the initialization setting in the first step comprises setting the starting duty ratio D of the motor_startAnd the rotation direction, and the working rotation speed V of the motor is set.

17. The control method of the switched reluctance motor according to claim 16, wherein: the start-up duty cycle D_startThe initial value range of (A) is 0.01-0.05.

18. The control method of the switched reluctance motor according to claim 1, wherein: and the motor in the second step is started in an ultra-low speed working mode, and the value range of the working rotating speed V of the motor in the ultra-low speed working mode is 40rpm-200 rpm.

19. The control method of the switched reluctance motor according to claim 1, wherein: the fourth step of judging whether the motor is locked up is realized by the following method: and setting a current threshold value or a torque threshold value or a rotating speed threshold value or a position signal threshold value when the motor is locked, and judging that the motor is locked once the current or the torque or the rotating speed or the position signal of the motor reaches or exceeds the set threshold value.

20. The control method of the switched reluctance motor according to claim 1, wherein: the step four is to judge whether the motor is locked up or not by the following steps:

21. The control method of the switched reluctance motor according to claim 20, wherein: the maximum accumulated time T_setThe value range of (a) is 60ms to 100 ms.

22. The control method of the switched reluctance motor according to claim 20, wherein: in the step 4b, if it is determined that the motor is locked, the following steps are continuously executed to realize the slow force application of the motor torque:

step 4D, outputting the duty ratio D in real time_rtN% increase every t milliseconds; whereinT and n are both preset constants;

wherein, the

Represents the duty cycle from D₁To D₂The maximum increase time of (c); d₁Represents the duty ratio, D, corresponding to the detected current torque M of the motor₂Representing the duty ratio corresponding to the motor torque M plus delta M; Δ M is the maximum increase in torque within a preset position signal angle interval, and Δ D is the increase per millisecond of a preset duty cycle.

23. The control method of the switched reluctance motor of claim 22, wherein: the value range of the increment delta D of the preset duty ratio per millisecond is 0.05% -0.2%.

24. The control method of the switched reluctance motor of claim 22, wherein: the value range of the maximum torque increase Delta M is 0.01 Nm-0.05 Nm.

25. The control method of the switched reluctance motor of claim 22, wherein: the value range of t in the step 4d is as follows: t is more than or equal to 0.5 and less than or equal to 5.

26. The control method of the switched reluctance motor of claim 22, wherein: the value range of n in the step 4d is as follows: n is more than or equal to 0.05 and less than or equal to 0.2.

27. The control method of the switched reluctance motor of claim 22, wherein: and the value angle of the preset position signal angle interval is the motor step angle.

28. The control method of the switched reluctance motor according to claim 20, wherein: in the step 4c, the set conducting winding phase change is realized through the following steps:

29. The control method of the switched reluctance motor of claim 1, wherein: the switched reluctance motor is a four-phase 8/6-level switched reluctance motor, and the motor step angle is 15 degrees.

30. The utility model provides a cooking machine, including switched reluctance motor, its characterized in that: the switched reluctance motor works by adopting the control method as claimed in any one of claims 1 to 29.

31. The utility model provides a cooking machine control method, the cooking machine is including agitating unit and the switched reluctance motor that can drive this agitating unit work, its characterized in that, the mode of cooking machine is including preventing grinding the mode, and this cooking machine's control method includes:

in the anti-crushing mode, the food processor controls the switched reluctance motor to rotate by adopting the control method according to any one of claims 1 to 29, and the switched reluctance motor drives the stirring device to stir the food materials in the food processor.