CN115706546A

CN115706546A - Control method of switched reluctance motor and food processor adopting control method

Info

Publication number: CN115706546A
Application number: CN202111307046.4A
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: 2021-08-06
Filing date: 2021-11-05
Publication date: 2023-02-17

Abstract

A control method of a switched reluctance motor is characterized by comprising the following steps: 1. starting a program and carrying out initialization setting; 2. energizing various windings of the motor according to a half-step driving excitation mode of the stepping motor; 3. the motor operates in a normal working mode; 4. whether the motor enters an overshoot mode or not is judged, if yes, a fifth step is executed; if not, returning to the third step; 5. within a limited time, the current conduction phase winding is continuously electrified, and the rotor generates oscillation at the stable zero position of the current conduction phase winding; 6. and adjusting the torque of the motor and returning to the fourth step. The invention also relates to a food processor applying the control method. The invention has the advantages that: various windings are electrified according to a half-step driving mode of the stepping motor, ultralow-speed operation of the switched reluctance motor is achieved, and continuous electrification is achieved for the current windings when external interruption is received, so that oscillation at a stable zero position (namely the effect of blade shaking) can be achieved after the motor is subjected to phase change every time, and food is prevented from being stuck.

Description

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

Technical Field

The present invention relates to a switched reluctance motor, and more particularly, to a control method of the switched reluctance motor and a food processor using the control method.

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 modern high-end food processors have the functions of cooking 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 is a novel speed regulating motor, and the speed regulating system has the advantages of a direct current speed regulating system and an alternating current speed regulating system and is a new generation of stepless speed regulating system. In the prior art, the switched reluctance motor is designed and improved in a plurality of ways under high-speed operation, but under the application scene of ultra-low-speed (such as 5-50 rpm) operation like cooking, research related to the dynamic performance of the switched reluctance motor is less, while the traditional motor cannot intelligently sense food if being applied to a cooking machine, 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 invention patent application with the application number of ZL201810472338.5, namely 'a novel ultra-low-speed large-torque switched reluctance motor', provides a novel ultra-low-speed large-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 a low-speed control method of the switched reluctance motor, and when the switched reluctance motor runs in a cooking mode, once the switched reluctance motor is blocked, the motor can easily find that the switched reluctance motor is blocked or food is stirred due to continuous rotation, so that the torque cannot be timely adjusted and intelligent automatic cooking cannot be realized.

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 control method for a switched reluctance motor, which can ensure stable operation of the motor and effectively prevent food from being stuck, in view of the above-mentioned current state of the art.

The second technical problem to be solved by the present invention is to provide a food processor using the control method of the switched reluctance motor in view of the above prior art.

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 initializing setting;

step two, starting the motor, and electrifying various windings of the motor according to a set excitation mode;

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

step four, judging whether the motor enters an overshoot mode (namely the rotating speed of the motor exceeds the rotating speed in the normal working mode), if so, executing the step five; if not, returning to the third step;

step five, continuously electrifying the current conducting phase winding (a single-phase conducting winding or a double-phase conducting winding) within a limited time;

and step six, setting corresponding torque adjustment quantity according to different oscillation states of the motor rotor, reducing the torque of the motor according to the corresponding torque adjustment quantity, and returning to the step four.

As another preferable mode, the step six includes the following steps: and step six, setting corresponding torque adjustment quantity according to different oscillation states of the motor rotor, reducing the torque of the motor according to the corresponding torque adjustment quantity until the torque of the motor is reduced to the set torque value or the time of the timer reaches the set window time, and then returning to the step three. Namely, the total reduction amount of the motor torque is set by an empirical value, and the reduction is stopped when a preset value is reached or the preset time is reached, an overshoot cycle is skipped, and the normal working operation mode is returned.

For convenience of operation and detection, the oscillation state of the motor rotor in the sixth step may be preferably determined according to the oscillation frequency or the oscillation period of the motor rotor within the limited time in the fifth step.

As a further preferred mode, the oscillation state of the rotor of the motor in the step six includes the following three cases:

A. setting a first torque regulating quantity without oscillation;

B. the oscillation is moderate, and the torque adjustment amount is zero;

C. setting a second torque adjustment amount when the oscillation is excessive;

the first torque adjustment amount and the second torque adjustment amount are positive numbers which are larger than zero, and the first torque adjustment amount is larger than the second torque adjustment amount.

Preferably, the oscillation state of the motor rotor is detected by the following method:

A. in the limited time of the step five, if the frequency of the motor rotor passing through the dead point from the phase change point is detected to be less than or equal to 1, no vibration exists, and the motor reduces the motor torque according to the set first torque adjustment quantity;

B. in the limited time of the step five, the frequency of the motor rotor passing through the dead point from the phase change point is detected to be less than or equal to the preset oscillation frequency, the oscillation is moderate, the motor torque is unchanged, and the motor generates the jitter effect;

C. in the limited time of the step five, if the frequency that the motor rotor passes through the dead point from the commutation point is detected to be greater than the preset oscillation frequency, the oscillation is excessive, and the motor reduces the motor torque according to the set second torque adjustment quantity;

the preset oscillation frequency is a positive integer greater than or equal to 2.

In order to ensure the reliable starting and operation of the motor, as a further preference, the following steps are also included between the second step and the third step: step 2a, detecting whether the motor is normally started, if so, executing a step three; if not, prompting the motor to start the fault, and after the fault is eliminated, circulating the step.

Preferably, the initialization setting in the first step may include setting the motor rotation speed V and the rotation direction, and setting the motor output torque Tor, the external interrupt count N, and the timer counting time t _j 。

Preferably, the value range of the set rotating speed V of the motor is as follows: v is more than or equal to 5rpm and less than or equal to 50rpm. The ultra-low speed rotating speed range is mainly aimed at a frying application mode of the food processor.

Preferably, the fourth step of determining whether the motor is overshot may be implemented by:

step 4a, clearing the external interrupt count N and counting the time t of the timer _j Resetting and restarting timing;

step 4b, detecting whether an external interrupt is received, if so, executing step 4c; if not, prompting a fault alarm after the external interrupt waiting time reaches the maximum set threshold;

step 4c, timing time t of the timer _j Whether or not to be greater than or equal to theoretical commutation time T _set If yes, executing an external interrupt instruction, and returning to the step 4a; if not, go to step five. If the external interruption comes ahead, the motor can be judged to be in overshoot, and the motor enters the overshoot mode at the moment.

Preferably, the limited time in the fifth step is a window time Δ T, and the window time Δ T = T _set -t _j ，T _set Is the theoretical commutation time of the motor. The window time enables the motor to generate an oscillation effect before the next interruption, prevents overshoot caused by the advance of the interruption, and ensures the running stability of the motor.

As a further preference, the adjustment of the motor torque can be realized by the following steps for the three oscillation states set in the above-mentioned step six:

step 6a, detecting whether the motor rotor has oscillation at the stable zero position of the current conduction phase, if so, continuing the step 6b; if not, go to step 6c;

step 6b, judging whether the current oscillation frequency exceeds the preset oscillation frequency N _set If yes, continuing to step 6d; if not, returning to the step 4c;

step 6c, judging whether the current motor output torque Tor is larger than a set first torque adjustment quantity delta Tor1, if so, then Tor = Tor-delta Tor1, and returning to the step 4c; if not, then Tor =0, and the step 4c is returned to;

step 6d, judging whether the current motor output torque Tor is larger than a set second torque adjustment quantity delta Tor2, if so, then Tor = Tor-delta Tor2, and returning to the step 4c; if not, tor =0, and the step 4c is returned to.

Preferably, in the step 4b, if no external interrupt is received, after the waiting time for the external interrupt reaches the maximum set threshold, a fault alarm is prompted, which is specifically implemented by adopting the following steps:

step 4b-1, timing time t of timer _j Whether or not to be greater than or equal to theoretical commutation time T _set If yes, continue the step4b-2; if not, returning to the step 4b;

step 4b-2, judging the timing time t of the timer _j Whether the maximum timing time T is greater than or equal to the set maximum timing time T _max If yes, prompting motor fault alarm and ending the program; if not, increasing the motor torque Tor by delta T every T time, and then returning to the step 4b, wherein the maximum set threshold value in the step 4b is the set maximum timing time T _max T and Δ T are both preset constants.

In order to avoid interference and prevent the motor from reporting errors frequently, as a further preferable mode, the step 4c of executing the external interrupt command and returning to the step 4a includes the following steps:

step 4c-1, judging the timing time t of the timer _j Whether or not to equal the theoretical commutation time T _set If yes, the conducting winding is conducted to change the phase according to the conducting sequence of the current motor rotating direction, and the step 4a is returned; if not, the timing time t of the timer is _j Greater than the theoretical commutation time T _set If the external interruption is delayed, which indicates that the torque moment of the motor is possibly not large enough, and the torque moment of the motor needs to be increased properly, the torque Tor of the motor is increased by delta T every T time, the phase of the conducting winding is changed according to the conducting sequence of the current motor rotating direction, and then the step 4a is returned, wherein T and delta T are preset constants.

In order to avoid excessive oscillation, the preset oscillation number N in the step 6b is preferable _set The value range of (A) is as follows: n is not less than 3 _set Less than or equal to 6. If the vibration is too small, the shaking effect of preventing the jamming can not be achieved, if the vibration is too large, the motor torque is too large, and the food is easily stirred and crushed, so that the vibration frequency of the motor needs to be controlled, and the motor torque is controlled to work within a range with a reasonable size.

In order to avoid the over-speed adjustment (e.g. the food is suddenly bounced off after being stuck, and the load is suddenly reduced) when the motor is operated at the ultra-low speed, the first torque adjustment amount Δ Tor1 in the step 6c preferably satisfies the following formula:

wherein the content of the first and second substances,

is a proportionality coefficient, A is a constant and is more than or equal to 1.5 and less than or equal to 2; delta T _d For a predetermined basic torque control quantity, Δ T _d Has a value range of 1.0 × 10 ^-3 Nm≤△T _d ≤5.0×10 ^-3 Nm. The first torque control variable Δ Tor1 takes into account the ratio between the current interruption time and the setpoint interruption time, and selects the adjustment range of the motor torque according to the different degrees of sudden load changes: if food is popped off at one time during cooking, the load of the motor is suddenly reduced, the interruption is advanced, and at the moment

The ratio is large, and the reduction amplitude of the motor torque is a little larger to prevent the motor rotating speed from being overshot; if the actual interruption time is close to the theoretical interruption time, the moment

The ratio is small, the actual torque of the motor operation is only slightly too large, and the magnitude of the motor torque reduction can be small.

Preferably, the second torque adjustment quantity Δ Tor2 in step 6d has a value range of: 5.0X 10 ^-4 Nm≤△T≤1.0×10 ^-3 Nm. When the oscillation is too much, in order to avoid the overlarge motor torque, the motor torque needs to be finely adjusted to gently reduce the torque in an oscillation state, so that the stable operation of the motor is ensured.

Preferably, the value range of t is as follows: t is more than or equal to 0.5 millisecond and less than or equal to 2 milliseconds, and the value t =1 millisecond is the best.

When the motor runs in an application scene of ultra-low speed rotation, in order to avoid food being smashed, the increased torque cannot be too large, and meanwhile, a certain rotation torque is ensured to complete phase change of the motor, and as an optimization, the value range of delta T is as follows: 1.0X 10 ^-4 Nm≤△T≤5.0×10 ^-4 Nm。

In order to ensure the reliability of the motorPreferably, the set maximum timer time T in the step 4b-2 is set _max The value range of (A) is as follows: t is less than or equal to 3s _max Less than or equal to 5s. When the interrupt waiting time exceeds the maximum timing time T _max If the interruption still comes, the motor is considered to be in fault, and warning needs to be prompted.

Preferably, the switched reluctance motor of the present application is a four-phase 8/6 stage switched reluctance motor.

In order to simplify the structure and facilitate the installation and detection, as a further preferable mode, the current position of the motor rotor is detected by a position sensor arranged on the motor, and the position sensor comprises a transmission type sensor and a shading disc; the transmission type sensor comprises a first sensor and a second sensor which are respectively and fixedly arranged on two adjacent stator salient poles, and the included angle between the first sensor and the second sensor relative to the central connecting line of the switched reluctance motor is 45 degrees; the transmission type sensor also comprises a third sensor and a fourth sensor which are respectively arranged on the two adjacent stator salient poles, the included angle of the third sensor and the fourth sensor relative to the central connecting line of the switched reluctance motor is 45 degrees, the included angle of the third sensor and the first sensor relative to the central connecting line of the switched reluctance motor is 7.5 degrees, and the included angle of the fourth sensor and the second sensor relative to the central connecting line of the switched reluctance motor is 7.5 degrees; the anti-dazzling screen is a disc arranged on the rotor shaft, and comprises an anti-dazzling screen structure matched with the salient poles of the rotor in number and cross section shape, and the anti-dazzling screen is perpendicular to the anti-dazzling screen. The four sensors can detect whether the switched reluctance motor oscillates in a stable zero position (single-phase winding conduction or bidirectional winding simultaneous conduction) in real time on the premise of not changing the structure of the motor.

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.

Compared with the prior art, the invention has the advantages that:

1. various windings of the switched reluctance motor are electrified by referring to an excitation mode of half-step driving of the stepping motor, so that a low-speed control method of the switched reluctance motor can be realized, and the motor can stably run in an ultra-low speed mode of 5-50 rpm;

2. when the motor is over-regulated, the current winding is continuously electrified, so that the switched reluctance motor can realize oscillation at a stable zero position (namely, the blade shaking effect is generated) after phase change every time, the motor torque can be reduced, the over-regulation of the rotating speed is avoided, food can be prevented from being stuck, the problem that food is broken due to the fact that the food is stuck in the blade during ultra-low-speed cooking is effectively solved, and Chinese cooking (such as rib frying, dish frying and the like) is facilitated;

3. aiming at different application scenes, the reduction of the motor torque is reasonably controlled, the overshoot of the motor rotating speed is effectively avoided, the stable operation of the motor can be ensured, and the operation reliability and the safety of equipment are improved;

4. on the basis of the rotor position detection structure of the existing switched reluctance motor, other structures of the motor do not need to be changed, the detection of the oscillation frequency of each phase winding in the stable zero position under the half-step driving mode is realized by arranging an additional pair of position sensors, the structure is simple and easy to realize, the manufacturing cost is low, and the practicability is high.

Drawings

FIG. 1 is a schematic diagram of a four-phase 8/6-level switched reluctance motor according to the prior art;

FIG. 2 is a schematic diagram of a four-phase 8/6-level switched reluctance motor according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a stable zero relationship between four sensors S1-S4 and a bridge arm according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of the continuous oscillation of a phase at a stable zero position according to an embodiment of the present invention;

fig. 5 is an overall step block diagram of a switched reluctance motor control method according to an embodiment of the present invention.

Fig. 6 is a flowchart of a method for controlling a switched reluctance motor according to an embodiment of the present invention.

Detailed Description

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

As shown in fig. 1, a four-phase 8/6-stage switched reluctance motor is adopted for a switched reluctance motor in the prior art, wherein 8 is the number of stator stages, 6 is the number of rotor stages, and the step angle of the motor is 15 degrees; the reluctance motor comprises 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 comprises a transmission type photoelectric sensor (comprising a photoelectric switch of an infrared transmitting tube and an infrared receiving tube) and a shading disc, and the structures of the transmission type photoelectric sensor and the shading disc are both the prior art;

the transmission type photoelectric sensor is provided with a first sensor S1 and a second sensor S2, the two sensors are respectively arranged on two adjacent salient poles (a + salient pole and d-salient pole) of the stator 1, wherein the centers of the a + salient poles of the first sensor S1 and the stator 1 are aligned, the centers of the d-salient poles of the second sensor S2 and the stator 1 are aligned, and the included angle formed by the first sensor S1 and the second sensor S2 relative to the center connecting line 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 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 vertical to the disc surface of the shading disc (namely, the shading disc comprises 6 shading sheets 3 which are uniformly distributed along the circumference), and the hatching shown in figure 1 is the hatching of the shading sheets which are vertically arranged;

when the convex teeth of the rotor 2 rotate to the positions where the first sensors S1 and S2 are arranged, the shading sheet 3 just penetrates through the grooves of the sensors, the light of the infrared emission tube is shaded to cut off the photosensitive transistors of the infrared emission tube, and the output state is 0; when the groove of the rotor is rotated to the positions of the first sensors S1 and S2, 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 turned on, the output state is 1, and in one rotor angular period (i.e., 60 ° shown in fig. 1), the first sensor S1 and the second sensor S2 generate two square wave signals with a phase difference of 15 ° and a 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.

The first sensor S1 and the second sensor S2 are also used for detecting external interrupt signals, when the first sensor S1 and the second sensor S2 detect sudden signal changes (namely jump occurs), the motor enters external interrupt, and the switched reluctance motor carries out phase change operation. For example, in the case of a rotation speed of 50rpm, the time difference between the two external interruptions is 50ms, and in actual use, the rotation speed of the motor is constantly changed along with the disturbance of the torque, so that the time difference between the two external interruptions in actual operation of the motor is constantly changed.

As shown in fig. 2, which is a schematic structural diagram of the switched reluctance motor of this embodiment, the motor of this embodiment also adopts a four-phase 8/6-stage switched reluctance motor, and on the basis of the prior art (i.e., fig. 1), this embodiment adds another two sensors, that is, a third sensor S3 and a fourth sensor S4 are further provided on two adjacent stator poles (a + salient pole and d-salient pole), and an included angle between the third sensor S3 and the fourth sensor S4 with respect to a central connecting line of the switched reluctance motor is also 45 °, an included angle between the third sensor S3 and the first sensor S1 with respect to the central connecting line of the switched reluctance motor is 7.5 °, and an included angle between the fourth sensor S4 and the second sensor S2 with respect to the central connecting line of the switched reluctance motor is 7.5 °.

According to the principle of minimum magnetic resistance of the switched reluctance motor, if a stable current is excited to a certain phase winding or two phase windings simultaneously, finally, the rotor is fixed at the stable zero position of the corresponding phase winding.

As shown in fig. 3, which is a schematic diagram of a relationship between four sensors and a stable zero position of a bridge arm in this embodiment, when the phase a is continuously energized, the stable zero position of the phase a is at a boundary of 10/00 of signals of the second sensor S2 and the first sensor S1; similarly, when the AD phase is continuously energized, the stable zero position of the AD phase is at 10/00 of the signals of the fourth sensor S4 and the third sensor S3.

In view of the characteristics of the switched reluctance motor, for an application scenario (such as cooking) of the food processor in an ultra-low speed operation mode, the motor control of the embodiment uses an excitation mode of half-step driving of the stepping motor as a reference, that is, when single-phase excitation is performed, the motor rotating shaft stops to a full-step position, after the driver receives a next pulse, the driver excites the other phase and keeps the original state of being continuously excited in succession, and the motor rotating shaft moves by a half-step angle and stops between two adjacent full-step positions.

For example, in a half-step driving mode using a stepping motor, taking clockwise rotation as an example, if the current conducting phase is C, the next conducting phase is BC, and the motors are sequentially conducted in the sequence of C → BC → B → AB → a → AD → D → CD → C → 8230; similarly, when the motor rotates counterclockwise, the motor is turned on in the order of CD → D → AD → A → AB → B → BC → C → CD \8230. Compared with the existing mode of conducting and phase-changing of the single-phase winding, the motor can run in a lower rotating speed range by adopting a half-step driving excitation mode, the motor of the embodiment can realize ultra-low speed running, and the rotating speed range is 5-50rpm.

When the motor is conducted in the phase change process according to the clockwise or anticlockwise sequence, if a continuous conducting current is given when the phase is changed every time, the motor rotor can generate a vibration effect near a stable zero position of a current conducting phase winding, namely, the rotor oscillates back and forth near the position of the stable zero position, so that the effect of blade shaking generated in the operation process of the food processor is achieved, and food is prevented from being stuck in the blade.

As shown in fig. 4, by using the principle of the stable zero position, when a certain phase winding or two phase windings of the switched reluctance motor are continuously conducted, the motor will be fixed at the stable zero position of the phase, and due to the existence of the inertia of the switched reluctance motor, the motor will continuously oscillate at the stable zero position until finally being stable. If the motor driving phase is changed from the C phase to the BC phase, the C phase is continuously conducted, the motor continuously oscillates near the stable zero position of the C phase, oscillation counting can be carried out every time the motor passes through the stable zero position, and the motor is finally stabilized at the stable zero position of the C phase.

Under cooking machine application scenario, above-mentioned this kind of oscillation can produce the rocking operation effect of blade, gets down at stable zero position promptly and rocks back to can also prevent that food raw and other materials from not being stuck in the blade.

In this embodiment, mainly aiming at the problem that when the motor is in overshoot (the rotation speed of the motor exceeds a set normal value), the motor is prevented from entering and stirring food when the motor suddenly flies (for example, a bone card flies by a blade in the process of frying pork ribs) to cause the rotation speed of the motor to be too fast or the motor runs unstably, and meanwhile, the motor is prevented from being stuck or cannot run normally due to the food being stuck, the embodiment adopts the setting mode of the position sensor shown in fig. 2, and the stable running of the motor in the overshoot mode is realized through the following control method.

Specifically, as shown in fig. 5, a block diagram of steps of the method for controlling a switched reluctance according to the present embodiment includes the following steps:

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

step two, starting the motor, and electrifying various windings of the motor according to a set excitation mode; in this embodiment, a half-step driving excitation method of the stepping motor is preferably adopted;

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

step four, judging whether the motor enters an overshoot mode, if so, executing step five; if not, returning to the third step;

step five, continuously electrifying the current conduction phase winding within a limited time, so that the motor rotor generates an oscillation effect at the stable zero position of the current conduction phase winding; under the excitation mode of half-step driving, the current conducted phase winding may be a single-phase winding or a two-phase conducted winding;

and step six, setting corresponding torque adjustment quantity according to the oscillation state (or oscillation intensity or oscillation grade) of the motor rotor, wherein the oscillation state is different, the corresponding torque adjustment quantity is different, the motor torque is reduced through the preset torque adjustment quantity according to application scenes in different oscillation states, and returning to the step four.

As another preferred method, the step six may also implement the reduction of the motor torque by adopting the following method:

and step six, setting corresponding torque adjustment quantity according to different oscillation states of a motor rotor, reducing the torque of the motor according to the corresponding torque adjustment quantity until the torque of the motor is reduced to the set torque value or the time of the timer reaches the set window time, and then returning to the step three. Namely, the total reduction amount of the motor torque is set by an empirical value, and the reduction is stopped when a preset value or preset time is reached, an overshoot cycle is skipped, and a normal working operation mode is returned.

The oscillation state (or oscillation intensity or oscillation grade) of the motor rotor of the embodiment includes the following three conditions:

A. setting a first torque regulating quantity without oscillation;

B. the oscillation is moderate, and the torque regulating quantity is zero;

C. setting a second torque adjustment amount when the oscillation is excessive;

the first torque adjustment amount and the second torque adjustment amount are positive numbers larger than zero, and the first torque adjustment amount is larger than the second torque adjustment amount.

The oscillation state of the rotor of the motor in the sixth step can be determined according to the oscillation frequency or the oscillation period within the limited time in the fifth step.

The method for judging the oscillation state through the oscillation times is realized through the following steps:

A. in the limited time of the step five, detecting that the frequency of the rotor of the motor passing through a dead point (namely an oscillation dead point) from a phase change point is less than or equal to 1, wherein no oscillation exists, and the motor reduces the torque of the motor according to a set first torque adjustment quantity;

B. in the limited time of the step five, if the frequency of the motor rotor passing through the dead point from the phase change point is detected to be less than or equal to the preset oscillation frequency, the oscillation is moderate, the oscillation state is kept, the motor torque is unchanged, and the motor generates the jitter effect;

wherein the preset oscillation frequency is a positive integer greater than or equal to 2.

In addition, the oscillation state can also be judged through the oscillation frequency and the oscillation period, excessive oscillation can be generated when the oscillation frequency is too high or the oscillation period is too short, the oscillation is moderate only in a proper frequency and period range, and if the oscillation frequency is not detected, the oscillation is not generated.

Whether the motor enters the overshoot mode or not can be judged by various modes in the prior art, the judgment can be simply realized by directly detecting the rotating speed and determining, the judgment can also be realized by detecting the time length of external interruption, and if the external interruption comes in advance, the torque is overlarge, the rotating speed is too high, and the motor enters the overshoot mode.

This control method of this embodiment is to motor overshoot stage, especially the motor is in the super low speed mode of operation in the cooking machine application, it is too fast (overshoot) to take place the rotational speed when the motor commutation, through continuing circular telegram for current winding, make switched reluctance motor can realize the oscillation at stable zero-position (produce the effect that the blade rocked promptly) after commutation at every turn, both can reduce motor torque from this, avoid the rotational speed overshoot, can avoid again to be stuck in the overshoot stage food, food stuck in the blade and lead to the broken problem of food when having solved super low speed fried dish effectively, the stationarity of motor operation has been guaranteed, the noise has been reduced simultaneously, be favorable to chinese style culinary art more (such as stir-fry spareribs, fried dish etc.).

As shown in fig. 6, a detailed flowchart based on the above step block diagram for further refinement in the present embodiment is shown:

the method comprises the following steps of firstly, starting a program, initializing and setting, and setting the rotating speed V and the rotating direction of a motor, wherein the switched reluctance motor is applied to a cooking scene and can operate in an ultra-low speed rotating speed range, the set value range of the rotating speed V of the motor is that V is more than or equal to 5rpm and less than or equal to 50rpm, and the rotating direction can be clockwise or anticlockwise;

meanwhile, the output torque of the motor is set to Tor, the external interrupt count is set to N, and the timing time of the timer is set to t _j And calculating the theoretical commutation time T when the motor operates at a constant speed according to the set rotating speed V _set ；

Assuming that the motor rotates at a constant speedIf the motor rotates for one circle, the output signals of the first sensor S1, the second sensor S2, the third sensor S3 and the fourth sensor S4 of this embodiment will output 48 external interrupts, the sum of the time differences of these consecutive 48 external interrupts is the time required for the motor to rotate for one circle, and the time difference between two adjacent external interrupts is T _set (namely theoretical commutation time), the time of one rotation of the motor is 48T _set The rotation speed (rpm) is defined as "revolutions per minute (60 s)" in seconds, and thus, the motor rotation speed

Therefore, the theoretical commutation time can be calculated by knowing the preset motor rotating speed V

Step two, electrifying various windings of the motor according to the excitation mode of the half-step drive of the stepping motor; taking the clockwise rotation as an example, if the current conducting phase is C, the next conducting phase is BC, and the motors are sequentially conducted in the sequence of C → BC → B → AB → AD → D → CD → C → 8230; similarly, if the motor rotates counterclockwise, the motor is turned on in the order of CD → D → AD → A → AB → B → BC → C → CD \8230.

Step 2a, detecting whether the motor is normally started, if so, executing a step three; if not, prompting the motor to start the fault, waiting for the fault to be eliminated, and circulating the step. Detecting whether the motor is normally started can be realized by various methods in the prior art, which is not described herein.

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

Step 4a, clearing the external interrupt count N and the timing time t of the timer _j And clearing and restarting timing.

Step 4b, detecting whether an external interrupt is received, if so, executing step 4c; if not, step 4b-1 is executed.

Step 4c, timing time t of the timer _j Whether the phase change time is more than or equal to the theoretical commutation time T _set If yes, executing step 4c-1; if notGo to step five. Wherein, the timing time t of the timer _j The actual commutation time of the motor is changed all the time because the rotating speed of the motor changes along with the disturbance of the torque.

Step 4b-1, timing time t of timer _j Whether or not to be greater than or equal to theoretical commutation time T _set If is, t _j ≥T _set If the interruption is slow, the load is large, the motor torque is insufficient, the motor commutation time is delayed, and the torque needs to be properly increased, the step 4b-2 is continued; if not, returning to the step 4b, and continuing to wait for the arrival of the external interrupt.

Step 4b-2, judging the timing time t of the timer _j Whether the maximum timing time T is greater than or equal to the set maximum timing time T _max If yes, prompting a motor fault alarm, and ending the program; if not, increasing the torque Tor of the motor by delta T every T time, and then returning to the step 4b, wherein T and delta T are preset constants, and the value range of delta T is as follows: 1.0X 10 ^-4 Nm≤△T≤5.0×10 ^-4 Nm, t is in the range of 0.5ms to 2ms, and t =1 ms is the best in this embodiment.

Step 4c-1, judging the timing time t of the timer _j Whether or not to equal the theoretical commutation time T _set If yes, the conducting winding is conducted to change the phase according to the conducting sequence of the current motor rotating direction, and the step 4a is returned; if not, the timing time t of the timer is _j Greater than the theoretical commutation time T _set Increasing delta T every T time when the motor torque Tor is increased, conducting the windings to change phases according to the conducting sequence of the current motor rotating direction, and then returning to the step 4a;

wherein T and Δ T are both preset constants, T is in a range of 0.5ms or more and 2ms or less, and T =1,ms is the best (ms represents millisecond) in this embodiment. Here, the maximum count time T _max The value range of (A) is as follows: t is less than or equal to 3s _max The time is less than or equal to 5s, and when the phase does not change for a long time (namely no interruption exists), the motor is considered to have a fault; the delta T is the torque increment of the motor in a set time, and is the adjustment of the motor torque under the application scene of interruption delay, for example, the food in the food processor is more, and the motorThe rotation is blocked, the phase change is possible to cause the seizure, and the torque of the motor needs to be increased by slowly applying force so as to realize the stable and continuous rotation of the motor.

Step five, continuously electrifying the current conducted phase winding within the window time delta t, so that the motor rotor generates an oscillation effect at the stable zero position of the current conducted phase winding; according to the winding conduction sequence under the clockwise or anticlockwise rotation of the motor in the half-step driving mode, the current conduction phase winding can be a single-phase conduction winding or a double-phase conduction winding, and the continuous energization time of the current winding is window time delta T = T _set -t _j I.e. for the defined time.

step 6b, judging whether the current oscillation frequency exceeds the preset oscillation frequency N _set (N _set Is an integer greater than 1), if yes, continue step 6d; if not, returning to the step 4c; predetermined number of oscillations N _set The value range of (A) is preferably as follows: n is not less than 3 _set Less than or equal to 6, according to the theory of operation of reluctance motor, when continuously circular telegram for current phase winding, then the motor can produce the oscillation under stable zero position, but the number of oscillations should not be too much, when the number of oscillations is too much, then it is too big to explain motor torque, needs suitably to reduce motor torque in order to reduce the oscillation to guarantee the stationarity of motor operation.

Step 6c, judging whether the current motor output torque Tor is larger than a set first torque adjustment quantity delta Tor1, if so, then Tor = Tor-delta Tor1, and returning to the step 4c; if not, then Tor =0, and the step 4c is returned;

the first torque adjustment amount Δ Tor1 satisfies the following equation:

wherein the content of the first and second substances,

is a proportionality coefficient, A is a constant and is more than or equal to 1.5 and less than or equal to 2; delta T _d For a predetermined basic torque control quantity, Δ T _d Is a preset empirical value with the value range of 1.0 multiplied by 10 ^-3 Nm≤△T _d ≤5.0×10 ^-3 Nm. The first torque adjustment quantity Δ Tor1 is used for adjusting the motor torque in an application scene where the motor speed is too fast, for example, when food is flicked off during spareribs frying, the motor load is suddenly changed from large to small, and at this time, the torque needs to be rapidly reduced, and the reduced torque quantity needs to be slightly larger.

Step 6d, judging whether the current motor output torque Tor is larger than a set second torque adjustment quantity delta Tor2, if so, then Tor = Tor-delta Tor2, and returning to the step 4c; if not, then Tor =0, and the step 4c is returned; the value range of the second torque adjustment quantity Δ Tor2 is as follows: 5.0X 10 ^-4 Nm≤△T≤1.0×10 ^-3 Nm。

The second torque adjustment quantity Δ Tor2 is used for adjusting the motor torque in an application scene of food entrapment, for example, food is entrapped in the blade during cooking, the blade is shaken through oscillation of a stable zero position, and then the food is shaken to prevent entrapment, but when the oscillation is too much, the torque needs to be reduced, but the quantity of the reduced torque needs to be smaller.

In the above specific control flowchart, there are four different adjustment amounts, i.e., Δ Tor1, Δ Tor2, Δ T and 0, for adjusting the output torque Tor of the motor, and in this embodiment, the magnitude sequence of the four adjustment amounts is set according to different application scenarios of the motor as follows: Δ Tor1 > - Δ Tor2 > - Δ T > 0;

when the load of the motor is suddenly reduced from big to small, and the rotating speed is too high due to too large torque of the motor, the torque needs to be quickly reduced, and the adjustment quantity of the torque reduction adopts delta Tor1;

when the motor is excessively oscillated, the torque needs to be reduced, the torque is not required to be excessively reduced, and the adjustment amount of the torque reduction is only delta Torr 2;

when the motor fails to realize phase change within the theoretical calculation time, the rotating torque of the motor is too small, the stable rotation of the motor needs to be realized by slowly applying force, the adjustment quantity of each torque increase is delta T, and the rotating speed overshoot is avoided;

in a special case, during cooking, if ribs are stuck, when the torque of the motor is increased, the ribs are suddenly popped up, then the rotating speed of the motor is suddenly increased, although the load of the motor is suddenly reduced from large to small, when the torque of the motor is too small, namely is smaller than the torque adjusting amount, at the moment, the output torque Tor of the motor is directly set to 0, namely Tor =0, the cutter is stopped, and the buffer deceleration of the motor can be realized.

The embodiment adopts a half-step driving mode by referring to a stepping motor, the operation of the motor in an ultra-low speed mode can be realized, the detection of the oscillation frequency of a motor winding in the zero position stabilization is realized by arranging four sensors, the control method is applied to the motor overshoot mode, the blade can generate the shaking effect when the food is stuck, the sticking is effectively reduced or prevented, and meanwhile, according to different application scenes in the motor overshoot mode, the motor torque is differentially regulated, the stable operation of the motor is realized, the problem that the food is stuck in the blade to cause the food to be broken when the food is fried at the ultra-low speed is effectively solved, the rotating speed is not overshot, and the safety and the reliability of the operation of the equipment are ensured. The control method of the embodiment is simple to implement, high in operability and practicability, and good in popularization and application prospect.

Claims

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

step one, starting a program and initializing setting;

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

step five, continuously electrifying the current conducting phase winding within a limited time;

2. The control method of the switched reluctance motor of claim 1, wherein: step six, the reduction of the motor torque is realized by adopting the following method:

and step six, setting corresponding torque adjustment quantity according to different oscillation states, reducing the torque of the motor according to the corresponding torque adjustment quantity until the torque of the motor is reduced to the set torque value or the time of the timer reaches the set window time, and then returning to the step three.

3. The control method of the switched reluctance motor of claim 1, wherein: the set excitation mode in the second step is a half-step driving excitation mode adopting a stepping motor.

4. The control method of the switched reluctance motor according to claim 1, wherein: and the continuous energization of the current phase winding in the step five is to continuously energize a single-phase winding or continuously energize a double-phase winding.

5. The control method of the switched reluctance motor according to claim 1, wherein: the oscillation state of the rotor of the motor in the sixth step can be determined according to the oscillation frequency or the oscillation period of the rotor in the limited time in the fifth step.

6. The control method of the switched reluctance motor according to claim 1, wherein: the oscillation state of the electronic rotor in the step six includes the following three conditions:

A. setting a first torque regulating quantity without oscillation;

B. the oscillation is moderate, and the torque regulating quantity is zero;

C. setting a second torque adjustment amount when the oscillation is excessive;

7. The control method of the switched reluctance motor according to claim 6, wherein: the oscillation state of the electronic rotor is detected by the following method:

A. in the limited time of the step five, the number of times that the motor rotor passes through a dead point from a phase change point is detected to be less than or equal to 1, no vibration exists, and the motor reduces the motor torque according to the set first torque adjustment quantity;

C. in the limited time of the step five, if the frequency that the rotor of the motor passes through the dead point from the commutation point is detected to be greater than the preset oscillation frequency, the oscillation is excessive, and the motor reduces the torque of the motor according to the set second torque adjustment quantity;

8. The control method of the switched reluctance motor of claim 1, wherein: the method also comprises the following steps between the second step and the third step:

step 2a, detecting whether the motor is normally started, if so, executing a step three; if not, prompting the motor to start the fault, waiting for the fault to be eliminated, and circulating the step.

9. The control method of the switched reluctance motor of claim 1, wherein: the initialization setting in the first step comprises setting the rotating speed V and the rotating direction of the motor, simultaneously setting the output torque of the motor Tor, the external interrupt count N and the timing time of the timer t _j 。

10. The control method of the switched reluctance motor according to claim 9, wherein: the value range of the set rotating speed V of the motor is as follows: v is more than or equal to 5rpm and less than or equal to 50rpm.

11. The control method of the switched reluctance motor of claim 1, wherein: and step four, judging whether the motor is overshot or not by adopting the following method:

step 4a, clearing the external interrupt count N and the timing time t of the timer _j Resetting and restarting timing;

step 4c, timing time t of the timer _j Whether the phase change time is more than or equal to the theoretical commutation time T _set If yes, executing an external interrupt instruction, and returning to the step 4a; if not, go to step five.

12. The control method of the switched reluctance motor according to claim 1, wherein: the limited time in the fifth step is window time delta T, and the window time delta T = T _set -t _j ，T _set Is the theoretical commutation time of the motor.

13. The control method of the switched reluctance motor according to claim 11, wherein: the adjustment of the motor torque in the sixth step is realized through the following steps:

step 6d, judging whether the current motor output torque Tor is larger than a set second torque adjustment quantity delta Tor2, if so, then Tor = Tor-delta Tor2, and returning to the step 4c; if not, tor =0, and the procedure returns to step 4c.

14. The control method of the switched reluctance motor according to claim 11, wherein: in the step 4b, if no external interrupt is received, after the waiting time of the external interrupt reaches the maximum set threshold, a fault alarm is prompted, and the method is specifically implemented by adopting the following steps:

step 4b-1, timing time t of timer _j Whether or not to be greater than or equal to theoretical commutation time T _set If yes, continuing to step 4b-2; if not, returning to the step 4b;

step 4b-2, judging the timing time t of the timer _j Whether the timing time is more than or equal to the set maximum timing time T _max If yes, prompting motor fault alarm and ending the program; if not, increasing the motor torque Tor by delta T every T time, and then returning to the step 4b, wherein the maximum set threshold value in the step 4b is the set maximum timing time T _max T and Δ T are both preset constants.

15. The control method of the switched reluctance motor of claim 11, wherein: in the step 4c, executing the external interrupt instruction and returning to the step 4a specifically includes the following steps:

step 4c-1, judging the timing time t of the timer _j Whether or not to equal the theoretical commutation time T _set If yes, the conducting winding is conducted to change the phase according to the conducting sequence of the current motor rotating direction, and the step 4a is returned; if not, increasing the torque Tor of the motor by delta T every T time, conducting the windings to change phases according to the conducting sequence of the current motor rotating direction, and then returning to the step 4a; wherein T and Δ T are both preset constants.

16. The control method of the switched reluctance motor according to claim 13, wherein: the preset oscillation frequency N in the step 6b _set Has a value range of：3≤N _set ≤6。

17. The control method of the switched reluctance motor of claim 13, wherein: the first torque adjustment amount Δ Tor1 in step 6c satisfies the following equation:

wherein the content of the first and second substances,

is a proportionality coefficient, A is a constant and is more than or equal to 1.5 and less than or equal to 2; delta T _d For a predetermined basic torque control quantity, Δ T _d Has a value range of 1.0 × 10 ^-3 Nm≤△T _d ≤5.0×10 ^-3 Nm。

18. The control method of the switched reluctance motor according to claim 13, wherein: the value range of the second torque adjustment quantity Δ Tor2 in the step 6d is as follows: 5.0X 10 ^-4 Nm≤△T≤1.0×10 ^-3 Nm。

19. The control method of the switched reluctance motor according to claim 14 or 15, wherein: the value range of t is as follows: t is more than or equal to 0.5ms and less than or equal to 2ms.

20. The control method of the switched reluctance motor according to claim 14 or 15, wherein: the value range of delta T is as follows: 1.0X 10 ^-4 Nm≤△T≤5.0×10 ^-4 Nm。

21. The control method of the switched reluctance motor according to claim 1, wherein: the set maximum timer time T in the step 4b-2 _max The value range of (A) is as follows: t is less than or equal to 3s _max ≤5s。

22. 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.

23. The control method of the switched reluctance motor of claim 1, wherein: the current position of the motor rotor is detected and obtained by a position sensor arranged on the motor, and the position sensor comprises a transmission type sensor and a shading disc;

the transmission type sensor comprises a first sensor and a second sensor which are respectively and fixedly arranged on two adjacent stator salient poles, and the included angle between the first sensor and the second sensor relative to the central connecting line of the switched reluctance motor is 45 degrees; the transmission type sensor also comprises a third sensor and a fourth sensor which are respectively arranged on the two adjacent stator salient poles, the included angle of the third sensor and the fourth sensor relative to the central connecting line of the switched reluctance motor is 45 degrees, the included angle of the third sensor and the first sensor relative to the central connecting line of the switched reluctance motor is 7.5 degrees, and the included angle of the fourth sensor and the second sensor relative to the central connecting line of the switched reluctance motor is 7.5 degrees;

the anti-dazzling screen is a disc arranged on the rotor shaft, and comprises anti-dazzling screen structures matched with the salient poles of the rotor in number and cross section shape, and the anti-dazzling screen is perpendicular to the anti-dazzling screen.

24. The utility model provides a cooking machine, including switched reluctance motor, its characterized in that: the switched reluctance motor adopts the control method as claimed in any one of claims 1 to 23.