CN113099557A - Electric heating equipment, temperature control method and device - Google Patents
Electric heating equipment, temperature control method and device Download PDFInfo
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- CN113099557A CN113099557A CN202110266427.6A CN202110266427A CN113099557A CN 113099557 A CN113099557 A CN 113099557A CN 202110266427 A CN202110266427 A CN 202110266427A CN 113099557 A CN113099557 A CN 113099557A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B1/00—Details of electric heating devices
- H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
- H05B1/0227—Applications
- H05B1/0252—Domestic applications
- H05B1/0258—For cooking
- H05B1/0261—For cooking of food
- H05B1/0263—Ovens
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- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J37/00—Baking; Roasting; Grilling; Frying
- A47J37/06—Roasters; Grills; Sandwich grills
- A47J37/0623—Small-size cooking ovens, i.e. defining an at least partially closed cooking cavity
- A47J37/0629—Small-size cooking ovens, i.e. defining an at least partially closed cooking cavity with electric heating elements
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Abstract
The disclosure relates to an electric heating device, a temperature control method and a temperature control device. The electric heating apparatus includes: the temperature sampling circuit comprises a temperature measuring sensor and is used for measuring the temperature of the furnace core of the electric heating equipment; the relay control circuit is connected with a load; and the control circuit board is connected with the temperature sampling circuit and the relay control circuit and is used for adjusting the duty cycle of the relay control circuit according to the furnace core temperature measured by the temperature sampling circuit and indicating the relay control circuit to control the load to be heated according to the adjusted duty cycle, wherein the heating duration in each duty cycle is a fixed value. This technical scheme can let the furnace core temperature fluctuate in a less within range, and the temperature range is little, and temperature control is more accurate, and is better to the edible material culinary art effect that the temperature requirement is higher such as roast cookies, and low cost.
Description
Technical Field
The disclosure relates to the technical field of intelligent household appliances, in particular to an electric heating device, a temperature control method and a temperature control device.
Background
At present, the temperature of cavity type electric heating equipment such as an oven is generally controlled by a silicon controlled rectifier or a relay, and the silicon controlled rectifier has the advantages that a program can be intelligently controlled in a closed loop mode, so that the temperature of a furnace core is accurately controlled, the temperature amplitude is small, and the disadvantage is high cost. The relay control has the advantages of low cost and disadvantages that the temperature of the furnace core controlled by the relay is controlled by a fixed duty ratio, an intelligent closed-loop control system is not formed, the temperature control is not accurate enough, the temperature range is large, and the cooking effect of food materials with higher temperature requirements such as baking cookies is poor.
Disclosure of Invention
The embodiment of the disclosure provides an electric heating device, a temperature control method and a temperature control device. The technical scheme is as follows:
according to a first aspect of the embodiments of the present disclosure, there is provided an electric heating apparatus, which is a cavity-type electric heating apparatus, including:
the temperature sampling circuit comprises a temperature measuring sensor and is used for measuring the temperature of the furnace core of the electric heating equipment;
the relay control circuit is connected with a load;
and the control circuit board is connected with the temperature sampling circuit and the relay control circuit and is used for adjusting the duty cycle of the relay control circuit according to the furnace core temperature measured by the temperature sampling circuit and indicating the relay control circuit to control the load to be heated according to the adjusted duty cycle, wherein the heating duration in each duty cycle is a fixed value.
In one embodiment, the temperature measuring sensor comprises a negative temperature coefficient NTC thermistor.
According to a second aspect of the embodiments of the present disclosure, there is provided a temperature control method applied to the above-mentioned electric heating apparatus, the method including:
starting heating, measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches the set temperature;
when the temperature of the furnace core is measured to be reduced to be lower than the set temperature, the power reduction heating is carried out, and when the measured temperature of the furnace core is lower than the set temperature after the power reduction heating is stopped, the power reduction heating is carried out for the next time until the preset heating time is reached; each power-down heating comprises: calculating the duty cycle of the current power reduction heating according to the basic duty cycle, the set temperature, the currently measured furnace core temperature, the heating duration of each previous power reduction heating and the heating stopping time; heating at the duty cycle of the current power reduction heating, and stopping the current power reduction heating when the temperature of the furnace core is measured to be higher than the set temperature in the current power reduction heating process;
wherein the heating duration in each duty cycle is a fixed value.
In one embodiment, the calculating the duty cycle of the current power-down heating according to the basic duty cycle, the set temperature, the currently measured core temperature, the heating duration of each previous power-down heating, and the heating stop time includes:
calculating the duty cycle u (n) of the nth power reduction heating according to the following formula:
wherein n is a natural number greater than or equal to 1; kp is proportional amplification factor, Ki is integral amplification factor, PV is real-time measured furnace core temperature, SV is set temperature, u0 is basic duty cycle, tnThe heating-off duration for the nth heating-down time, TnThe heating time length of the nth power reduction heating is adopted. .
In one embodiment of the present invention,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
add and then round, add u 0.
In one embodiment of the present invention,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
rounded up and added up separately, plus u 0.
According to a third aspect of the embodiments of the present disclosure, there is provided a temperature control apparatus applied to the above-mentioned electric heating device, the apparatus including:
the first heating module is used for starting heating and measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches the set temperature;
the second heating module is used for performing power reduction heating when the temperature of the furnace core is measured to be reduced below a set temperature, and performing power reduction heating for the next time when the measured temperature of the furnace core is less than the set temperature after the power reduction heating is stopped until preset heating time is reached; each power-down heating comprises: calculating the duty cycle of the current power reduction heating according to the basic duty cycle, the set temperature, the currently measured furnace core temperature, the heating duration of each previous power reduction heating and the heating stopping time; heating at the duty cycle of the current power reduction heating, and stopping the current power reduction heating when the temperature of the furnace core is measured to be higher than the set temperature in the current power reduction heating process;
wherein the heating duration in each duty cycle is a fixed value.
In one embodiment, the second heating module comprises:
calculating the duty cycle u (n) of the nth power reduction heating according to the following formula:
wherein n is a natural number greater than or equal to 2; kp is proportional amplification coefficient, Ki is integral amplification coefficient, PV is real-time measured furnace core temperature,SV is set temperature, u0 is base duty cycle, tnThe heating-off duration for the nth heating-down time, TnThe heating time length of the nth power reduction heating is adopted.
According to a fourth aspect of embodiments of the present disclosure, there is provided a non-transitory computer readable storage medium storing computer instructions which, when executed by a processor, implement the steps in the above method.
The technical scheme provided by the embodiment of the disclosure can have the following beneficial effects:
this embodiment can use the relay to realize intelligent closed-loop control, lets the furnace core temperature undulant in a less within range, and the temperature range is little, and temperature control is more accurate, and is better to the edible material culinary art effect that temperature requirement such as roast cookies is higher, and this disclosure uses the relay to realize heating temperature control, low cost.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.
Fig. 1 is a block diagram illustrating a structure of an electric heating apparatus according to an exemplary embodiment.
FIG. 2 is a circuit diagram illustrating a temperature sampling circuit according to an exemplary embodiment.
Fig. 3 is a circuit diagram illustrating a relay control circuit according to an exemplary embodiment.
FIG. 4 is a flow chart illustrating a method of temperature control according to an exemplary embodiment.
FIG. 5 is a graph illustrating a temperature change according to an exemplary embodiment.
FIG. 6 is a graph illustrating a temperature change according to an exemplary embodiment.
Fig. 7 is a graph illustrating temperature variation when heating is controlled using an existing fixed duty cycle, according to an exemplary embodiment.
FIG. 8 is a block diagram illustrating a temperature control device according to an exemplary embodiment.
Detailed Description
Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the exemplary embodiments below are not intended to represent all implementations consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.
The present disclosure provides an electric heating apparatus, which is a cavity type electric heating apparatus such as an electric oven, etc., and fig. 1 is a block diagram illustrating a structure of an electric heating apparatus according to an exemplary embodiment. As shown in fig. 1, the electric heating apparatus includes: a temperature sampling circuit 11, a relay control circuit 12, a load 13 and a control circuit board 14.
FIG. 2 is a circuit diagram illustrating a temperature sampling circuit according to an exemplary embodiment, the temperature sampling circuit 11 including a temperature measuring sensor for measuring a core temperature of the electric heating apparatus, as shown in FIG. 2; rntc in the circuit diagram shown in fig. 2 is a temperature measuring sensor, which may be an NTC thermistor, and Pin _ io is connected to the control circuit board, so that the control circuit board can obtain a temperature value sensed by the temperature measuring sensor. The temperature sampling circuit shown in fig. 2 is a common temperature sampling circuit and will not be described in detail here.
A relay control circuit 12 connected to the load 13 for controlling the heating time and the non-heating time of the load 13, for example, fig. 3 is a circuit diagram of a relay control circuit according to an exemplary embodiment, a Pin _ io in the relay control circuit 12 is connected to the control circuit board 14, when the control circuit board 14 inputs a high level through the Pin _ io, a transistor Q2 is in a saturated conduction state, a coil of the relay is energized, a contact is closed, the power supply of the load 13 is switched on, and the load 13 is controlled to start heating; when the control circuit board 14 inputs a low level through the Pin _ io, the transistor Q2 is turned off, the relay coil is powered off, the contact is opened, the power supply of the load is cut off, and the load is controlled to stop heating, so that the heating time and the non-heating time of the load can be controlled by controlling the input high level time and low level time.
And the control circuit board 14 is connected with the temperature sampling circuit 11 and the relay control circuit 12 and used for adjusting the duty cycle period of the relay control circuit 12 according to the furnace core temperature measured by the temperature sampling circuit 11 and indicating that the relay control circuit 12 controls the heating of the load 13 according to the adjusted duty cycle period, wherein the heating duration in each duty cycle period is a fixed value, so that the heating is carried out in the duty cycle period, namely the heating duration is switched to the unheated duration (duty cycle period-fixed value) after the heating duration is fixed value, and then the heating duration is switched to the unheated duration (duty cycle-fixed value) after the heating duration is fixed value.
Here, the present disclosure may start to heat the core temperature to a set temperature with full power, perform power-down heating with a certain duty cycle when the core temperature falls below the set temperature, stop heating when the temperature is greater than the set temperature, perform next heating with this duty cycle according to a next duty cycle calculated according to the change of the core temperature, thus continuously adjust the duty cycle by the real-time measured core temperature, since the heating duration in each duty cycle is a fixed value, the heating duty cycle is changed, and the duty cycle adjustment will cause the core temperature to change, thus realizing intelligent closed-loop control, making the core temperature fluctuate in a small range, the temperature amplitude is small, the temperature control is more accurate, the effect for cooking food materials with higher temperature requirements such as baking cookies is better, and the present disclosure uses a relay to realize the heating temperature control, the cost is low.
The present disclosure also provides a temperature control method, and fig. 4 is a flowchart illustrating a temperature control method according to an exemplary embodiment, which may be applied to the above-mentioned electric heating apparatus, as shown in fig. 4, the temperature control method including the following steps 401 and 402:
in step 401, heating is started, the core temperature is measured in real time, and when the measured core temperature reaches the set temperature, heating is stopped.
Here, when heating is started, the electric heating apparatus may use full power heating until the core temperature is heated to a set temperature, the temperature sampling circuit outputs the measured core temperature to the control circuit board, and the control circuit board may measure that the core temperature reaches the set temperature, at which time, a low level may be input to the relay control circuit, power supply to the load is cut off, and the load is controlled to stop heating.
In step 402, when the measured temperature of the furnace core is reduced to below the set temperature, the current power reduction heating is performed, and when the measured temperature of the furnace core after the current power reduction heating is stopped is less than the set temperature, the next power reduction heating is performed until the preset heating time is reached.
After the load is controlled to stop heating for a period of time, the temperature of the furnace core is reduced to be lower than the set temperature, the control circuit board measures that the temperature of the furnace core is reduced to be lower than the set temperature through the temperature sampling circuit, at the moment, the control circuit board can control the current power reduction heating to be carried out, when the measured temperature of the furnace core after the current power reduction heating is stopped is lower than the set temperature, the next power reduction heating is carried out, and therefore the power reduction heating can be circularly carried out for multiple times until the preset heating time is reached.
Here, each power-down heating includes: calculating the duty cycle of the current power reduction heating according to the basic duty cycle, the set temperature, the currently measured furnace core temperature, the heating duration of each previous power reduction heating and the heating stopping time; heating at the duty cycle of the current power reduction heating, and stopping the current power reduction heating when the temperature of the furnace core is measured to be higher than the set temperature in the current power reduction heating process; and the heating duration in each duty cycle is a fixed value.
Here, the value of the basic duty cycle is related to the service life of the electric heating device, and when the service life needs to be long, the basic duty cycle needs to be increased, and the switching frequency of the high and low levels of the input relay is decreased, so as to prolong the service life of the relay.
Here, the set temperature is a temperature that the electric heating apparatus needs to reach when performing work such as cooking or a temperature set by a user.
Here, the measured core temperature changes in real time, and the lower the measured core temperature is, the smaller the duty cycle of the power-down heating this time obtained by calculation is, and since the heating duration in each duty cycle is a fixed value, the time for non-heating will be reduced, the heating duration will be increased relative to the non-heating duration, and the heating power is increased, so that the core temperature is rapidly increased, and the core temperature is more stable.
Here, the larger the ratio of the heating stop time length to the heating time length of each previous power-down heating, the larger the calculated duty cycle of the current power-down heating, where the heating stop time length of each power-down heating is the time length from the end time of the current power-down heating to the start time of the next power-down heating, and the heating time length of each power-down heating is the time length from the start time to the end time of the current power-down heating.
In a possible embodiment, the duty cycle of the current reduced-power heating calculated according to the basic duty cycle, the set temperature, the currently measured core temperature, the heating duration of each previous reduced-power heating, and the heating stop time in the above method may be implemented as the following step a 1:
in step a1, the duty cycle u (n) of the nth heating power reduction is calculated according to the following formula:
wherein n is a natural number greater than or equal to 1; kp is the proportional amplification factor, Ki is the integral amplification factor, PVFor real-time measurement of core temperature, SV is set temperature, u0 is base duty cycle, tnThe heating-off duration for the nth heating-down time, TnThe heating time length of the nth power reduction heating is adopted.
Here, the value of Kp is an empirical value, and may be set by a developer based on experience. Kp (PV-SV) plays a large role when the furnace core temperature PV measured by the NTC thermistor in real time is different from the set temperature SV, and is 0 when PV and SV are equal. Taking the set temperature SV of 200 degrees as an example, Kp may be set to 0.3, and when the furnace core temperature PV-the set temperature SV measured in real time is-4, Kp (PV-SV) — 1.2, u (n) is decreased by-1.2, and accordingly, as the duty cycle is decreased, the heating duration is increased relative to the non-heating duration, the heating power is increased, and the furnace core temperature is rapidly increased.
Here, the integral amplification factor Ki can be obtained by actual tests.
Here, fig. 5 is a temperature change graph showing a temperature change of a core temperature when heating is performed according to the following method when the horizontal axis in fig. 5 is a time axis in units of s, the numerical axis is a temperature axis in units of degrees, fig. 5 is a temperature change graph showing a set temperature SV in units of 200 degrees, a base duty cycle u0 in units of 12, Kp in units of 0.3, and Ki in units of 1:
starting: starting heating, measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches the set temperature of 200 ℃;
u (1) period: when the temperature of the furnace core is measured to be reduced below the set temperature, the 1 st power reduction heating is carried out, and the calculation is carried out
Because the power is reduced for 1 time, the heating is performed
Is absent, so that
Assuming that PV is 200 degrees, u (1) is 12, so that when the 1 st reduced power heating is performed, heating can be performed according to a duty ratio of 6s/12s, namely 6s is heated, 6s is not heated until the measured furnace core temperature PV is 200 degrees higher than the set temperature, and the 1 st reduced power heating is finished;
after the 1 st power reduction heating is finished, when the temperature of the furnace core is measured to be reduced to the set temperature, the 2 nd power reduction heating is carried out, and at the moment, the heating time T of the 1 st power reduction heating can be obtained through statistics1I.e. the heating time length for heating according to the fixed value/u (1) duty ratio, the heating stop time t for the 1 st reduced power heating1The time length from the 1 st reduced power heating end to the 2 nd reduced power heating start;
u (2) period: calculating
Assuming that u (2) is 13 obtained through actual calculation, when the 2 nd reduced power heating is performed, periodic heating can be performed according to a duty ratio of 6s/13s, namely heating for 6s, not heating for 7s, reheating for 6s and not heating for 7s, until the measured furnace core temperature PV is 200 degrees higher than the set temperature, and the 2 nd reduced power heating is finished;
after the 2 nd power reduction heating is finished, when the temperature of the furnace core is measured to be reduced to the set temperature, the 3 rd power reduction heating is carried out, and at the moment, the heating time T of the 2 nd power reduction heating can be obtained through statistics2I.e. the heating time length for heating according to the fixed value/u (2) duty ratio, the heating stop time t for the 1 st reduced power heating2The time length from the end of the 2 nd reduced power heating to the beginning of the 3 rd reduced power heating;
u (3) period: computing
Assuming that the actual calculation yields u (3) to 14, then at the 3 rd reduced power heating,the periodic heating can be carried out according to the duty ratio of 6s/14s, namely the heating is carried out for 6s, the heating is not carried out for 8s, until the furnace core temperature PV is measured to be 200 ℃ higher than the set temperature, and the 3 rd power reduction heating is finished;
after the 3 rd time of power reduction heating, when the temperature of the furnace core is measured to be reduced below the set temperature, the 4 th time of power reduction heating is carried out, and at the moment, the heating time T of the 3 rd time of power reduction heating can be obtained through statistics3I.e. the heating time length for heating according to the fixed value/u (3) duty ratio, and the heating stop time t for the 3 rd time of power-down heating3The time length from the end of the 3 rd time of power reduction heating to the beginning of the 4 th time of power reduction heating;
u (4) period: computing
Assuming that u (4) is 15 obtained through actual calculation, when the 4 th reduced power heating is performed, periodic heating can be performed according to a duty ratio of 6s/15s, namely heating is performed for 6s, and heating is not performed for 9s, until the measured furnace core temperature PV is 200 degrees higher than the set temperature, and the 4 th reduced power heating is finished;
after the 4 th power reduction heating is finished, when the temperature of the furnace core is measured to be reduced below the set temperature, the 5 th power reduction heating is carried out, and at the moment, the heating time T for the 4 th power reduction heating can be obtained through statistics at first4I.e. the heating time length for heating according to the fixed value/u (4) duty ratio, the heating stop time t for the 4 th reduced power heating4The time length from the end of the 4 th reduced power heating to the beginning of the 5 th reduced power heating;
u (5) period: computing
Suppose that the actual calculation yields u (5) 16, so that heating is performed at the 4 th reduced powerAnd periodically heating according to the duty ratio of 6s/15s, namely heating for 6s, not heating for 9s, until the furnace core temperature PV is measured to be 200 ℃ higher than the set temperature, and ending the 5 th power reduction heating.
Alternatively, for example, fig. 6 is a graph showing a temperature change according to an exemplary embodiment, where as shown in fig. 6, the temperature is set to 200 degrees, u0 is 12, Kp is 0.3, and Ki is 4, then:
starting: starting heating, measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches the set temperature of 200 ℃;
when the temperature of the furnace core is measured to be reduced below the set temperature, 1 st power reduction heating is carried out: computing
Because the power is reduced for 1 time, the heating is performed
Is absent, so that
Assuming that PV is 200 degrees, u (1) is 12, so that when the 1 st reduced power heating is performed, heating can be performed according to a duty ratio of 6s/12s, namely 6s is heated, 6s is not heated until the measured furnace core temperature PV is 200 degrees higher than the set temperature, and the 1 st reduced power heating is finished;
after the 1 st power reduction heating is finished, when the temperature of the furnace core is measured to be reduced to the set temperature, the 2 nd power reduction heating is carried out, and at the moment, the heating time T of the 1 st power reduction heating can be obtained through statistics1I.e. the heating time length for heating according to the fixed value/u (1) duty ratio, the heating stop time t for the 1 st reduced power heating1The time length from the 1 st reduced power heating end to the 2 nd reduced power heating start;
when the temperature of the furnace core is measured to be reduced below the set temperature, carrying out power reduction heating for the 2 nd time: computing
Assuming that u (2) is 14 obtained through actual calculation, when the 2 nd reduced power heating is performed, periodic heating can be performed according to a duty ratio of 6s/14s, namely heating for 6s, not heating for 8s, reheating for 6s and not heating for 8s, until the measured furnace core temperature PV is 200 degrees higher than the set temperature, and the 2 nd reduced power heating is finished;
after the 2 nd power reduction heating is finished, when the temperature of the furnace core is measured to be reduced to the set temperature, the 3 rd power reduction heating is carried out, and at the moment, the heating time T of the 2 nd power reduction heating can be obtained through statistics2I.e. the heating time length for heating according to the fixed value/u (2) duty ratio, the heating stop time t for the 1 st reduced power heating2The time length from the end of the 2 nd reduced power heating to the beginning of the 3 rd reduced power heating;
when the temperature of the furnace core is measured to be reduced below the set temperature, performing power reduction heating for the 3 rd time: computing
Assuming that u (3) is 16 obtained by actual calculation, when the 3 rd reduced power heating is performed, periodic heating can be performed according to a duty ratio of 6s/14s, namely heating is performed for 6s, and heating is not performed for 8s until the measured furnace core temperature PV is 200 degrees higher than the set temperature, and the 3 rd reduced power heating is finished. It is assumed that when the measured core temperature is less than the set temperature, such as PV of 196 degrees,
and actually calculating u (3) as 15, so that when the 3 rd time of power reduction heating is carried out, periodic heating can be carried out according to the duty ratio of 6s/15s, namely 6s is heated, and 7s is not heated, so that when the furnace core temperature is measured to be lower, the heating time length proportion is properly increased, the heating power is increased, and the temperature can be quickly increased.
It can be known from the comparison between fig. 5 and fig. 6 that when the integral constant Ki is large, a reasonable duty ratio can be reached quickly, so that the temperature is stable quickly, and it is reasonable to set Ki to 4 through testing. Here, according to different set temperatures, experiments can be performed according to the control method provided by the present disclosure, and more reasonable parameters u0, Kp, Ki are obtained through testing, so as to achieve a better temperature control effect, for example, the following table 1 shows specific parameters and corresponding test effects with a better temperature control effect.
TABLE 1
Here, fig. 7 is a graph showing a temperature change when heating is controlled using an existing fixed duty ratio according to an exemplary embodiment, and an existing commonly used relay controls the core temperature to be a fixed duty ratio control, and when the NTC thermistor measures that the core temperature is less than a set temperature, the relay heats at a duty ratio of 6s/12s (the relay is turned on for 6s, and turned off for 6s), and when the NTC thermistor measures that the core temperature is greater than the set temperature, the relay is turned off, thereby circulating. The disadvantage is that no intelligent closed loop control system is formed, the temperature of the furnace core fluctuates in a large range, the temperature of the furnace core in the whole heating process is as shown in fig. 7, and the temperature amplitude after stabilization is about 215.6-192.1-23.5 degrees. And fig. 5 and 6 are temperature change graphs illustrating that, when heating is performed by using the temperature control method provided by the present disclosure, the furnace core temperature starts to be heated to the set temperature at full power, when the furnace core temperature falls below the set temperature, the power is reduced for a certain duty cycle, when the temperature is higher than the set temperature again, the heating is stopped, and the duty cycle of the next power-reducing heating calculated according to the method of the present disclosure is performed for the next power-reducing heating. As shown in fig. 5, after stabilization, the temperature amplitude is about 206.3-198.6 ═ 7.7 degrees, and the comparison shows that by using the temperature control method provided by the present disclosure, intelligent closed-loop control can be realized, the temperature of the furnace core fluctuates in a small range, the temperature amplitude is small, the temperature control is more accurate, and the cooking effect of food materials with higher temperature requirements such as baking cookies is better.
The present disclosure can also be experimentally verified for a plurality of set temperatures, and the stable rear core temperature, temperature amplitude and relative error of the temperature control method using the present disclosure are recorded, and the stable rear core temperature, temperature amplitude and relative error of the existing fixed duty ratio at the same set temperature are recorded, and the result is as follows
Shown in table 2.
TABLE 2
As can be seen from table 2, the intelligent closed-loop control that this disclosure adopted compares with current fixed duty cycle control, and the stove core temperature is more stable and accurate after stabilizing, and temperature control is more accurate, and is better to the edible material culinary art effect that the temperature requirement is higher such as roast cookies.
In one embodiment of the present invention,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
add and then round, add u 0.
In one embodiment of the present invention,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
rounded up and added up separately, plus u 0.
Here, Kp (PV-SV) and
the two terms can be added after being rounded, and can also be added and rounded, and the operation process of rounding after adding can not be carried outThe temperature curve changes caused by the change of Kp (PV-SV) are seen in the test curve, and the change is smoother. The addition of the integrals shows the change of the temperature curve caused by the change of Kp (PV-SV), and as shown in FIG. 5, when the actual temperature PV-set temperature SV is-4 during the operation, the Kp (PV-SV) is acted and u (t) is reduced properly. Kp (PV-SV) and
rounding after addition is better.
Fig. 8 is a block diagram illustrating a temperature control apparatus that may be implemented as part or all of an electronic device via software, hardware, or a combination of both, according to an example embodiment. As shown in fig. 8, the interphone control device includes:
the first heating module 801 is used for starting heating, measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches a set temperature;
the second heating module 802 is configured to perform power reduction heating this time when the measured temperature of the furnace core is reduced to below the set temperature, and perform power reduction heating next time when the measured temperature of the furnace core after the power reduction heating is stopped is smaller than the set temperature until a preset heating time is reached; each power-down heating comprises: calculating the duty cycle of the current power-down heating according to the currently measured furnace core temperature, the heating time and the non-heating time of each previous power-down heating; heating at the duty cycle of the current power reduction heating, and stopping the current power reduction heating when the temperature of the furnace core is measured to be higher than the set temperature in the current power reduction heating process;
wherein the heating duration in each duty cycle is a fixed value.
In one embodiment, the second heating module 802 includes: calculating the duty cycle u (n) of the nth power reduction heating according to the following formula:
wherein n is a natural number greater than or equal to 2; kp is a ratioExample amplification factor, Ki is integral amplification factor, PV is the real-time measured core temperature, SV is set temperature, u0 is base duty cycle, tnThe n-th unheated time, TnThe heating time is the nth time.
The present disclosure also provides a non-transitory computer-readable storage medium, in which instructions, when executed by a processor in an apparatus applied to an intercom, enable the apparatus to perform the steps of the above temperature control method, the method comprising:
starting heating, measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches the set temperature;
when the temperature of the furnace core is measured to be reduced to be lower than the set temperature, the power reduction heating is carried out, and when the measured temperature of the furnace core is lower than the set temperature after the power reduction heating is stopped, the power reduction heating is carried out for the next time until the preset heating time is reached; each power-down heating comprises: calculating the duty cycle of the current power-down heating according to the currently measured furnace core temperature, the heating time and the non-heating time of each previous power-down heating; heating at the duty cycle of the current power reduction heating, and stopping the current power reduction heating when the temperature of the furnace core is measured to be higher than the set temperature in the current power reduction heating process;
wherein the heating duration in each duty cycle is a fixed value.
In an embodiment, the calculating the duty cycle of the current power-down heating according to the currently measured core temperature and the heating time and the non-heating time of each previous power-down heating includes:
calculating the duty cycle u (n) of the nth power reduction heating according to the following formula:
wherein n is a natural number greater than or equal to 1; kp is proportional amplification factor, Ki is integral amplification factor, and PV is real-time measurementCore temperature of the volume, SV set temperature, u0 base duty cycle, tnThe n-th unheated time, TnThe heating time is the nth time.
In one embodiment of the present invention,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
add and then round, add u 0.
In one embodiment of the present invention,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
rounded up and added up separately, plus u 0.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
It will be understood that the present disclosure is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.
Claims (9)
1. An electric heating device, characterized in that, electric heating device is cavity class electric heating device, includes:
the temperature sampling circuit comprises a temperature measuring sensor and is used for measuring the temperature of the furnace core of the electric heating equipment;
the relay control circuit is connected with a load;
and the control circuit board is connected with the temperature sampling circuit and the relay control circuit and is used for adjusting the duty cycle of the relay control circuit according to the furnace core temperature measured by the temperature sampling circuit and indicating the relay control circuit to control the load to be heated according to the adjusted duty cycle, wherein the heating duration in each duty cycle is a fixed value.
2. Electrically heated apparatus as claimed in claim 1 wherein the temperature measuring sensor comprises a negative temperature coefficient NTC thermistor.
3. A temperature control method, applied to the above electric heating apparatus, the method comprising:
starting heating, measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches the set temperature;
when the temperature of the furnace core is measured to be reduced to be lower than the set temperature, the power reduction heating is carried out, and when the measured temperature of the furnace core is lower than the set temperature after the power reduction heating is stopped, the power reduction heating is carried out for the next time until the preset heating time is reached; each power-down heating comprises: calculating the duty cycle of the current power reduction heating according to the basic duty cycle, the set temperature, the currently measured furnace core temperature, the heating duration of each previous power reduction heating and the heating stopping time; heating at the duty cycle of the current power reduction heating, and stopping the current power reduction heating when the temperature of the furnace core is measured to be higher than the set temperature in the current power reduction heating process;
wherein the heating duration in each duty cycle is a fixed value.
4. The method of claim 3, wherein the duty cycle of the current reduced power heating calculated according to the basic duty cycle, the set temperature, the currently measured core temperature, the heating duration of each previous reduced power heating, and the heating stop time comprises:
calculating the duty cycle u (n) of the nth power reduction heating according to the following formula:
wherein n is a natural number greater than or equal to 1; kp is proportional amplification factor, Ki is integral amplification factor, PV is real-time measured furnace core temperature, SV is set temperature, u0 is basic duty cycle, tnThe heating-off duration for the nth heating-down time, TnThe heating time length of the nth power reduction heating is adopted.
5. The method of claim 4,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
add and then round, add u 0.
6. The method of claim 4,
wherein, the [ alpha ], [ beta ]]For the rounding symbols u (n) is Kp (PV-SV) and
respectively rounded and addedPlus u 0.
7. A temperature control device, applied to the above electric heating apparatus, the device comprising:
the first heating module is used for starting heating and measuring the temperature of the furnace core in real time, and stopping heating when the measured temperature of the furnace core reaches the set temperature;
the second heating module is used for performing power reduction heating when the temperature of the furnace core is measured to be reduced below a set temperature, and performing power reduction heating for the next time when the measured temperature of the furnace core is less than the set temperature after the power reduction heating is stopped until preset heating time is reached; each power-down heating comprises: calculating the duty cycle of the current power reduction heating according to the basic duty cycle, the set temperature, the currently measured furnace core temperature, the heating duration of each previous power reduction heating and the heating stopping time; heating at the duty cycle of the current power reduction heating, and stopping the current power reduction heating when the temperature of the furnace core is measured to be higher than the set temperature in the current power reduction heating process;
wherein the heating duration in each duty cycle is a fixed value.
8. The apparatus of claim 7, wherein the second heating module comprises:
calculating the duty cycle u (n) of the nth power reduction heating according to the following formula:
wherein n is a natural number greater than or equal to 2; kp is proportional amplification factor, Ki is integral amplification factor, PV is real-time measured furnace core temperature, SV is set temperature, u0 is basic duty cycle, tnThe heating-off duration for the nth heating-down time, TnThe heating time length of the nth power reduction heating is adopted.
9. A non-transitory computer readable storage medium storing computer instructions, wherein the computer instructions, when executed by a processor, implement the steps of the method of any one of claims 3 to 6.
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| CN114711643A (en) * | 2022-03-31 | 2022-07-08 | 海信家电集团股份有限公司 | Oven and temperature control method thereof |
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