CN108021158B

CN108021158B - Temperature control method of electric oven and electric oven

Info

Publication number: CN108021158B
Application number: CN201711270911.6A
Authority: CN
Inventors: 韩洪涛; 丁文龙
Original assignee: Hilongchuan Co ltd
Current assignee: Hilongchuan Co ltd
Priority date: 2017-12-05
Filing date: 2017-12-05
Publication date: 2020-05-19
Anticipated expiration: 2037-12-05
Also published as: CN108021158A

Abstract

The invention discloses a temperature control method of an electric oven and the electric oven, comprising the following steps: obtaining ambient temperature T_{Environment(s)}(ii) a According to the ambient temperature T_{Environment(s)}Determining a temperature compensation coefficient T_Compensation(ii) a In the working process of the electric oven, the electric oven is detected regularlyTemperature T of the core_{Furnace core}And using said temperature compensation coefficient T_CompensationFor the temperature T of the furnace core_{Furnace core}Performing compensation; according to the set temperature T_{Setting up}And compensated core temperature T_{Core compensation}And determining the heating power of the heating pipe, and further adjusting the heating power of the heating pipe in the electric oven. According to the invention, the temperature of the core of the electric oven is compensated according to the ambient temperature, and the compensated core temperature is used for replacing the actual core temperature and combining with the set temperature to determine the heating power of the heating pipe, so that the heat loss of the electric oven caused by the heat dissipation problem can be compensated, the influence of the ambient temperature on the temperature control of the electric oven is reduced, the temperature control of the electric oven is more accurate, and the baked food is more delicious.

Description

Temperature control method of electric oven and electric oven

Technical Field

The invention belongs to the technical field of kitchen appliances, relates to an electric oven, and particularly relates to a method for accurately controlling the heating temperature of the electric oven and the electric oven designed based on the temperature control method.

Background

With the popularization of small household appliances in kitchens of Chinese families, the electric oven is taken as a representative of western typical kitchen appliances and is enjoyed by more and more Chinese families. The electric oven can be used for preparing meat-quality barbecue foods such as roast chicken and roast duck, and can also be used for baking wheaten foods such as bread and cake.

The conventional electric oven determines the set temperature according to the set temperature input (or selected) by a user or a baking mode selected by the user, then determines the heating power of a heating pipe in the electric oven according to the set temperature and the detected temperature of a furnace center of the electric oven, and further controls the heating pipe to heat so as to bake and bake food. In the actual use process, because the electric oven has the heat dissipation problem, the lower the ambient temperature is, the more the heat is dissipated, and the more the heat released by the heating pipe is to reach the same set temperature. The influence of the ambient temperature on the temperature control of the electric oven is neglected in the conventional electric oven, and when the temperature of a furnace core of the electric oven is close to the set temperature, the temperature of the furnace core is about 10 ℃ of floating change above and below the set temperature due to the difference of the ambient temperature. For example, in summer when the temperature is generally high, when the set temperature is 100 ℃, the temperature of the furnace core of the electric oven is finally stabilized at about 95 ℃; in winter with generally low temperature, when the set temperature is 100 ℃, the temperature of the core of the electric oven is finally stabilized at about 115 ℃, and at this time, if the electric oven works in a fermentation mode, the problems of dead baking, incapability of fermenting and the like of dough can occur. Because the inaccurate problem of electric oven temperature control that causes of ambient temperature's change can make the food that comes out through the electric oven baking have "pressing from both sides living" or toast excessive scheduling problem, then experience the influence that produces certain degree to user's use.

Disclosure of Invention

The invention aims to provide a temperature control method of an electric oven, which adopts a mode of compensating the temperature of a furnace core according to the ambient temperature, so that the actual temperature of the furnace core of the electric oven can be closer to and more stable at the set temperature of a user in the using process, the temperature control accuracy of the electric oven is further improved, and the baking effect of food is improved.

In order to solve the technical problems, the invention adopts the following technical scheme:

in one aspect of the present invention, a method for controlling temperature of an electric oven is provided, including: obtaining ambient temperature T_{Environment(s)}(ii) a According to the ambient temperature T_{Environment(s)}Determining a temperature compensation coefficient T_Compensation(ii) a In the working process of the electric oven, the temperature T of the furnace core of the electric oven is detected regularly_{Furnace core}And using said temperature compensation coefficient T_CompensationFor the temperature T of the furnace core_{Furnace core}Performing compensation; according to the set temperature T_{Setting up}And compensated core temperature T_{Core compensation}Determining the heating power P of a heating pipe; the heating power of a heating pipe in the electric oven is adjusted to be P.

Wherein the compensated core temperature T_{Core compensation}It should satisfy: at T_{Environment(s)}<At 25 ℃ T_{Core compensation}Greater than the actual core temperature T_{Furnace core}And the lower the ambient temperature is, the temperature compensation coefficient T_CompensationThe larger; and at T_{Environment(s)}>At 25 ℃ T_{Core compensation}Less than the actual core temperature T_{Furnace core}And the higher the ambient temperature is, the higher the temperature compensation coefficient T_CompensationThe smaller. So that the electric oven can be used in any seasonThe temperature of the furnace core can be as close as possible to the set temperature T_{Setting up}And the accuracy of temperature control of the electric oven is improved.

As means for obtaining said temperature compensation coefficient T_CompensationAccording to the environment temperature T, the preferable realization mode of (1) can be realized in advance_{Environment(s)}And temperature compensation coefficient T_CompensationThe corresponding relation between the two forms a comparison table and the comparison table is stored in an electric oven; in the actual use process, the environment temperature T can be obtained_{Environment(s)}Determining the ambient temperature T by searching the comparison table_{Environment(s)}Corresponding temperature compensation coefficient T_Compensation。

As a measure of the ambient temperature T_{Environment(s)}In a preferred implementation of (1), the ambient temperature T is obtained_{Environment(s)}In the process, the method comprises the following steps: detecting the current temperature T0 of the electric oven when the electric oven is powered on and started; reading the latest N times of environmental temperature values stored in a memory of the electric oven, and sequentially defining the environmental temperature values as T1 and T2 … … TN according to time sequence; calculating the average value Tave of T1 and T2 … … TN; if T0<Tave- △ T1, i.e. T when the ambient temperature is significantly reduced_{Environment(s)}if Tave- △ T1 is not more than T0 is not more than Tave + △ T1, namely the environment temperature is close to the environment temperature stored before, T0 is added, T1 and T2 … … TN are all replaced by T0, the temperature value stored in the temporary storage position in the memory is cleared, and if the environment temperature is not less than T0 and not more than Tave + △ T1_{Environment(s)}(T2+ … … + TN + T0)/N, and recording T0 as the latest ambient temperature value, and forming the latest N ambient temperature values with the T2 … … TN; if T0>Tave + △ T1, there may be two conditions of ring temperature rise and electric oven residual temperature, in order to distinguish these two conditions to obtain accurate environment temperature and avoid the influence of the residual temperature of the electric oven on the temperature control of the electric oven, the invention compares T0 with the average value Tb of the temperature value stored in the temporary storage position of the memory, if T0 is more than or equal to Tb + △ T2, it is judged that T0 is the residual temperature of the electric oven, T0 is discarded, and T is made_{Environment(s)}if Tb- △ T2 is less than or equal to T0 is less than or equal to Tb +/△ T2, that is the detected current temperature T0 is close to the temp. value stored in temporary storage, if N-1 temp. values are stored in temporary storage position, it is judged that it is seasonal change, the ring temp. is raised, at this moment, T- △ T2 is made to be greater than or equal to Tb + △ T2_{Environment(s)}Is equal toAveraging the N-1 temperature values and T0, replacing the T1 and T2 … … TN by taking the N-1 temperature values and T0 as the latest N times of environmental temperature values, and clearing the temperature values at the temporary storage positions in the memory; if the temperature values stored in the temporary storage positions are less than N-1, the observation is continued, and T is enabled at the moment_{Environment(s)}Tave, and storing T0 in the staging location; if T0<Tb- △ T2, the observation is continued, and T is made_{Environment(s)}Tave, and if the temperature value stored in the temporary storage position is less than N-1, storing T0 in the temporary storage position; if N-1 temperature values have been stored in a temporary storage location, the oldest written temperature value in the temporary storage location is discarded and T0 is stored in the temporary storage location because T0 is more likely to be the current ambient temperature.

preferably, the △ T1 is 3 ℃, the △ T2 is 2 ℃, and the temperature N is preferably 3.

In order to reduce the cost and avoid adding an annular temperature sensor on the electric oven, the current temperature T0 is preferably collected and converted by a sensor for detecting the temperature of the core of the electric oven and is detected only once when the electric oven is powered on and started.

As a preferred realization for determining the heating power P of the heating tube, the invention aims to increase the temperature of the core of the electric oven to the set temperature T as quickly as possible_{Setting up}Preferably at T_{Setting up}-T_{Core compensation}When the temperature is more than or equal to 30 ℃, controlling the heating pipe to rapidly heat at a preset fixed heating power; at T_{Setting up}-T_{Core compensation}<At 30 ℃, in order to realize accurate temperature control and avoid the temperature T of the furnace core_{Furnace core}At a set temperature T_{Setting up}In the vicinity of which large fluctuations occur, the PID algorithm is preferably used to calculate the heating power P of the heating tube, i.e. in accordance with T_{Setting up}And T_{Core compensation}The heating power of the heating tube is calculated by adopting the following formula:

P_k＝P_k-1+ΔP_k；

ΔP_k＝k_p(e_k-e_k-1)+k_ie_k+k_d(e_k-2e_k-1+e_k-2)；

wherein e is_kIs T_{Setting up}Compensating temperature T of furnace core at kth sampling moment_{Core compensation}The temperature difference of (a); e.g. of the type_k-1Is T_{Setting up}The furnace core compensation temperature T at the k-1 sampling moment_{Core compensation}The temperature difference of (a); e.g. of the type_k-2Is T_{Setting up}The furnace core compensation temperature T at the k-2 sampling moment_{Core compensation}The temperature difference of (a); k is a radical of_p、k_i、k_dIs a control coefficient; p_k-1Calculating the heating pipe power for the kth-1 th sampling moment; p_kThe heating tube power at the kth sampling moment.

Preferably, when the electric oven is operated in the fermentation mode, k is preferably set_p＝4.8、k_i＝0.6、k_d4.8; when the electric oven is operated in a mode other than fermentation, it is preferable to set k_p＝4.8、k_i＝0.4、k_d＝4.4。

In another aspect, the present invention provides an electric oven including a temperature sensor, a memory, a controller, and a heating pipe; the temperature sensor is used for detecting the temperature T of the furnace core of the electric oven_{Furnace core}And is used for detecting the current temperature T0 of the electric oven when the electric oven is powered on and started up; the storage is used for storing the ambient temperature of the electric oven in the near-term use; when the electric oven is powered on and started, the controller determines the current ambient temperature T0 according to the ambient temperature stored in the memory and the current temperature T0 detected by the temperature sensor_{Environment(s)}And according to said ambient temperature T_{Environment(s)}Determining a temperature compensation coefficient T_Compensation(ii) a In the working process of the electric oven, the controller detects the temperature T of the furnace core collected by the temperature sensor at regular time_{Furnace core}And using said temperature compensation coefficient T_CompensationFor the temperature T of the furnace core_{Furnace core}Compensating for the temperature T_{Setting up}And compensated core temperature T_{Core compensation}And determining the heating power P, and controlling the heating pipe to operate at the heating power P to heat the food in the electric oven.

Compared with the prior art, the invention has the advantages and positive effects that: according to the invention, the temperature of the core of the electric oven is compensated according to the ambient temperature, the compensated core temperature is utilized to replace the actual core temperature and is combined with the set temperature, and the heating power of the heating pipe is determined, so that the heat loss of the electric oven caused by the heat dissipation problem can be compensated, the influence of the ambient temperature on the temperature control of the electric oven is reduced, the temperature control of the electric oven is more accurate, the baked food is more delicious, and the use experience of a user is improved.

Other features and advantages of the present invention will become more apparent from the detailed description of the embodiments of the present invention when taken in conjunction with the accompanying drawings.

Drawings

Fig. 1 is a partial structural schematic view of an embodiment of an electric oven according to the present invention;

FIG. 2 is a schematic block diagram of a portion of an electrical circuit of an embodiment of the present invention;

fig. 3 is a control flow chart of an embodiment of a temperature control method for an electric oven according to the present invention.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

As shown in fig. 1, the electric oven of this embodiment includes a casing 10, a front opening of the casing 10 is provided with a glass door 20, the door 20 is provided with a push-pull handle 21, and the opening of the casing 10 can be closed by the glass door 20. Inside the housing 10, heating pipes are installed, and generally include an upper heating pipe 31 and a lower heating pipe 32. The upper heating pipe 31 and the lower heating pipe 32 may be respectively provided one or two. The upper heating pipe 31 and/or the lower heating pipe 32 are controlled to generate heat, and the heat is released to heat the food in the electric oven, so that the food is baked or roasted. The upper and

lower heating pipes

31 and 32 are used for heating simultaneously, so that food in the electric oven is heated up and down, and the balance of food heating can be improved. A display 14 and a knob 15 are provided on the front panel 13 of the housing 10, information such as a set temperature, an operation mode, and an ambient temperature can be displayed through the display 14, and parameters such as a set temperature, a heating time, a heating mode, and an operation mode of the electric oven can be set through the knob 15.

In order to stabilize the temperature of the core of the electric oven at the set temperature input or selected by the user during the operation of the electric oven, in this embodiment, a temperature sensor is further disposed in the electric oven, and is used for detecting the temperature of the core of the electric oven and transmitting the detected temperature to a controller on a main control board of the electric oven, which is shown in fig. 2. The controller calculates the heating power of the heating pipe according to the set temperature input by the user and the furnace core temperature collected by the temperature sensor, and then controls the heating pipe to generate heat according to the calculated heating power so as to meet the baking requirement of the user on food.

Considering that the temperature of the core of the electric oven is difficult to be accurately stabilized at the set temperature when the electric oven is used in different seasons due to the heat dissipation problem, and then the baked food is prone to have the problems of 'pinching' or excessive baking, the present embodiment provides a control strategy for compensating the temperature of the core according to the ambient temperature, and determining the heating power of the heating pipe according to the compensated temperature of the core and the set temperature so as to improve the temperature control accuracy of the electric oven. In order to realize accurate detection of the ambient temperature of the electric oven on the basis of not increasing the ambient temperature sensor, the present embodiment preferably adopts the existing sensor for detecting the temperature of the oven core in the electric oven, and when the electric oven is powered on and started, the sensor is also used as the ambient temperature sensor to detect the ambient temperature of the electric oven, so that the temperature control requirement is met, and the increase of the hardware cost of the electric oven is avoided.

The main control board of the electric oven can be further provided with a memory, such as an EEPROM memory, which is connected with the controller and used for storing historical data of the ambient temperature and the like.

Referring to fig. 2, a detailed description will be made of a specific control process of the temperature control method of the electric oven of the present embodiment, as shown in fig. 3, including the following steps:

s301, starting a temperature sensor to acquire the current temperature T0 when the electric oven is powered on and started up each time;

the power-on starting-up refers to alternating current power-on starting-up, is a starting-up process after alternating current of the electric oven is cut off, and is different from a process from standby to starting-up of the electric oven. When the electric oven is not used for a long time, the power plug can be unplugged, and the alternating current is turned off. When the temperature sensor is used next time, a long time may pass, and the ambient temperature may change significantly (for example, the ambient temperature may change significantly due to seasonal change), so that the ambient temperature needs to be detected again. The electric oven usually does not take a long time, generally hours, but at most days, from standby to startup, so that the ambient temperature does not change obviously, and the temperature compensation coefficient can be determined directly according to the ambient temperature obtained during alternating current startup, so as to perform temperature compensation on the temperature of the oven core.

In addition, the temperature sensor may be a specially-arranged ambient temperature sensor, that is, a sensor specially used for detecting the ambient temperature, or may be directly used for sampling and detecting the temperature of the oven core in the electric oven. The latter detection mode is preferably adopted in the present embodiment to save the hardware cost of the electric oven.

Since the temperature collected by the temperature sensor when the electric oven is powered on and started up may be the ambient temperature or the residual temperature of the electric oven, the present embodiment defines the temperature as the current temperature T0, and the temperature is detected only once when the electric oven is powered on and started up.

S302, determining the ambient temperature T_{Environment(s)}；

In order to distinguish whether the current temperature T0 detected by the temperature sensor is the ambient temperature or the residual temperature of the electric oven, the present embodiment adopts the following determination method:

firstly, the environmental temperature of the electric oven in the previous N times of use, namely the latest N times of environmental temperature values, is stored in the EEPROM memory of the electric oven, and is sequentially defined as T1 and T2 … … TN according to time sequence. When the electric oven is shipped, default values can be given to the N ambient temperature values, for example, T1-T2-T … … -TN-25 ℃, and these parameters are modified according to the actual ambient temperature values during the subsequent actual use of the electric oven.

Secondly, judging whether the current temperature T0 is more than 35 ℃, if T0>And if the temperature is 35 ℃, taking T0 as invalid data, reading the last environmental temperature value stored in the EEPROM as the current environmental temperature T_{Environment(s)}(ii) a If T0 is less than or equal to 35 ℃, calculating the average value Tave of T1 and T2 … … TN, and then determining the current ambient temperature T according to the current temperature T0 and the average value Tave_{Environment(s)}Namely:

if the current temperature T0 is much lower than Tave, for example, T0<Tave- △ T1, △ T1 can be between 2 ℃ and 5 ℃, and the current temperature T0 is considered to be the actual environment temperature T_{Environment(s)}I.e. T_{Environment(s)}T0. Since the current ambient temperature is much lower than the historical ambient temperature stored in the memory, it can be considered that a seasonal change has occurred, such as summer when the electric oven was used last time, and a significant decrease in ambient temperature when the electric oven was used this time in winter. In order to obtain a more accurate ambient temperature during the later use of the electric oven, in this embodiment, it is preferable to replace all the N historical ambient temperature values stored in the memory with T0, i.e. T1 ═ T2 ═ … … ═ TN ═ T0, so that the temperature of the oven core can be compensated by a more real ambient temperature during the use of the electric oven in this season, and the temperature control of the electric oven is more accurate.

when T0< Tave- △ T1, the temperature value stored in the temporary storage position in the memory can be directly cleared.

if the current temperature T0 is close to the historical ambient temperature stored in the memory, for example, Tave- △ T1 is equal to or less than T0 is equal to or less than Tave + △ T1, it can be considered that the season of using the electric oven this time is the same season as the previous N times of using the electric oven, and the temperature difference is not large_{Environment(s)}The temperature value is (T2+ … … + TN + T0)/N, and T0 is used as the latest ambient temperature value, and the latest N ambient temperature values are formed with the T2 … … TN, that is, T1 ═ T2, T2 ═ T3 … … TN-1 ═ TN, and TN ═ T0, and the temperature values are stored in the EEPROM memory instead of the originally stored T1 and T2 … … TN.

if the current temperature T0 is much higher than the historical ambient temperature stored in the memory, for example, T0> Tave + △ T1, there may be two cases, one is that the ambient temperature is increased due to seasonal alternation, for example, winter when the electric oven is used last time, and the ambient temperature is obviously increased when the electric oven is used this time in summer, and the other is that the temperature is increased due to the residual temperature of the electric oven, and at this time T0. should be ignored in order to identify whether the current temperature T0 is the ambient temperature or the residual temperature of the electric oven, the present embodiment proposes the following determination method:

calculating an average value Tb of the temperature values stored in the temporary storage position of the memory;

if the current temperature T0 is far higher than the temperature value stored in the temporary storage position, for example, T0 is more than or equal to Tb + △ T2, and DELTA.T 2 can be between 2 ℃ and 4 ℃, the current temperature T0 can be considered as the residual temperature of the electric oven_{Environment(s)}Leave it as Tave and discard T0 for no storage;

if the current temperature T0 is close to the temperature value stored in the temporary storage position, for example, Tb- △ T2 is equal to or less than T0 is equal to or less than Tb +. DELTA.T 2, and N-1 temperature values are stored in the temporary storage position, it indicates that a season change has occurred, and at this time, the current ambient temperature T can be made to be equal to the current ambient temperature T_{Environment(s)}The average value of the N-1 temperature values and the T0 at the temporary storage position is equal, the N-1 temperature values and the T0 at the temporary storage position are used as the latest N times of environmental temperature values, T1 and T2 … … TN in the memory are replaced, and the temperature values at the temporary storage position in the memory are cleared; if the temperature values stored in the temporary storage position are less than N-1, T0 cannot be determined as the current environment temperature, and T can be set at the moment_{Environment(s)}Tave and saves T0 in the temporary location of memory for subsequent determination;

if the current temperature T0 is far lower than the temperature value stored in the temporary storage location, such as T0<Tb- △ T2, it is necessary to further determine whether T0 is at ambient temperature_{Environment(s)}Tave, and if the temperature value stored in the temporary storage position in the memory is less than N-1, storing T0 in the temporary storage position; if N-1 temperature values are stored in the temporary storage position, the temperature value written into the temporary storage position at the earliest time is discarded, and T0 is stored in the temporary storage position.

examples of N ═ 3, △ T1 ═ 3 ℃ and Δ T2 ═ 2 ℃ are as follows:

(1) in the same season, when the environmental temperature difference is not large, if the temperature value stored in the memory is as the following table:

T1

T2

T3

T4

T5

wherein, T1, T2 and T3 are the last three ambient temperature values, and T4 and T5 are the temperature values of the temporary storage location. If T0 belongs to Tave-3 ℃ and Tave +3 ℃, the T1, T2 and T3 are shifted to the left by one, the T0 is stored in the position of T3, and the current ambient temperature is T_{Environment(s)}Updating the temperature data in the EEPROM memory for (T2+ T3+ T0)/3, as follows:

T2

T3

T0

T4

T5

(2) when the temperature difference is negative from summer to winter, if the temperature values stored in the memory are as follows:

T1

T2

T3

T4

T5

wherein, T1, T2 and T3 are the last three ambient temperature values, and T4 and T5 are the temperature values of the temporary storage location. Then, if T0<(Tave-3 ℃), the current environmental temperature T_{Environment(s)}Updating the temperature data in the EEPROM memory, T1, T2, T3, T0, and T4 and T5 are cleared as follows:

T0

air conditioner

Air conditioner

(3) If the temperature difference is positive from winter to summer, the temperature values stored in the memory are as follows:

T1

T2

T3

T4

T5

wherein, T1, T2 and T3 are the last three ambient temperature values, T4 and T5 are the temperature values of the temporary storage position, and the storage time of T5 is earlier than that of T4. Then, Tb ═ (T4+ T5)/2 is calculated; if T0>(Tave +3 ℃) and T0 epsilon (Tb-2 ℃, Tb +2 ℃), the current environmental temperature T_{Environment(s)}When the temperature data in the EEPROM memory is updated, and T4, T5 and T0 are sequentially moved to T1, T2 and T3 on the left side, T4 and T5 are cleared, which is (T0+ T4+ T5)/3, as shown in the following table:

T5

T4

T0

air conditioner

Air conditioner

(4) If the temperature is the residual temperature of the electric oven, if the temperature value stored in the memory is as the following table:

T1

T2

T3

T4

T5

wherein, T1, T2 and T3 are the last three ambient temperature values, T4 and T5 are the temperature values of the temporary storage position, and the storage time of T5 is earlier than that of T4. Then, Tb ═ (T4+ T5)/2 is calculated; if T0>(Tave +3 ℃ C.), and T0>(Tb +2 ℃) at this time, the ambient temperature T_{Environment(s)}And (T1+ T2+ T3)/3, the data in the EEPROM memory is not updated. If T0>(Tave +3 ℃ C.), and T0<(Tb-2 ℃) at this time, the ambient temperature T_{Environment(s)}Updating the temperature data in the EEPROM memory to (T1+ T2+ T3)/3, keeping T1, T2 and T3 unchanged, moving T4 to T5, and storing T0 in T4, as shown in the following table:

T1

T2

T3

T0

T4

thus, the ambient temperature T of the electric oven is determined_{Environment(s)}。

S303, according to the environmental temperature T_{Environment(s)}Determining a temperature compensation coefficient T_Compensation；

This embodiment employs establishing an ambient temperature T_{Environment(s)}And temperature compensation coefficient T_CompensationThe current environment temperature T of the electric oven is determined by the way of a comparison table of corresponding relations between the ambient temperature T and the ambient temperature T_{Environment(s)}Corresponding temperature compensation coefficient T_Compensation. The comparison table can be stored in the EEPROM memory in advance for the calling use of the controller. Temperature compensation coefficient T_CompensationShould be set to follow T_CompensationWith T_{Environment(s)}A law of increase and decrease of, and T_{Environment(s)}<At 25 ℃ T_CompensationTaking a positive value; t is_{Environment(s)}>At 25 ℃ T_CompensationTaking a negative value. For example, the following comparison table is established:

T_{environment(s)}(℃)	0-5	6-10	11-15	16-20	21-25	26-30	31-35
								T_Compensation(℃)	23	17	12	8	2	-3	-8

The controller determines the current ambient temperature T by looking up the comparison table_{Environment(s)}Corresponding temperature compensation coefficient T_Compensation。

S304, selecting the working mode of the electric oven and determining the set temperature T_{Setting up}And heating time, starting the electric oven to operate.

S305, detecting the temperature T of the furnace core of the electric oven at regular time_{Furnace core}And compensating the coefficient T according to the temperature_CompensationTo furnace core temperature T_{Furnace core}Compensating and calculating the compensated furnace core temperature T_{Core compensation}；

After the electric oven is started to operate, the controller detects the temperature T of the furnace core collected by the temperature sensor at regular time_{Furnace core}And calculating the compensated core temperature T_{Core compensation}＝T_{Furnace core}+T_Compensation. In the present embodiment, the coefficient T is compensated for due to temperature_CompensationThe set rule of (2) follows: t is_CompensationWith T_{Environment(s)}Is increased and decreased, and T_{Environment(s)}<At 25 ℃ T_CompensationTaking a positive value; t is_{Environment(s)}>At 25 ℃ T_CompensationTakes a negative value, therefore, the compensated core temperature T_{Core compensation}The calculation formula of (c) can be defined as: t is_{Core compensation}＝T_{Furnace core}+T_Compensation. If the temperature compensation coefficient T is designed_CompensationThe set rule of (2) follows: t is_CompensationWith T_{Environment(s)}Is increased, and T_{Environment(s)}<At 25 ℃ T_CompensationTaking a negative value; t is_{Environment(s)}>At 25 ℃ T_CompensationTaking a positive value, the compensated furnace core temperature T_{Core compensation}The calculation formula of (c) should be defined as: t is_{Core compensation}＝T_{Furnace core}-T_Compensation. In summary, the compensated core temperature T_{Core compensation}It should satisfy: at T_{Environment(s)}<At 25 ℃ T_{Core compensation}Greater than the actual core temperature T_{Furnace core}And the lower the ambient temperature is, the temperature compensation coefficient T_CompensationThe larger; and at T_{Environment(s)}>At 25 ℃ T_{Core compensation}Less than the actual core temperature T_{Furnace core}And the higher the ambient temperature is, the higher the temperature compensation coefficient T_CompensationThe smaller the setting requirement, the higher the temperature control accuracy of the electric oven. At ring temperature T_{Environment(s)}When the temperature is 25 ℃, T can be placed_Compensation0 deg.C, i.e. without temperature T for the core_{Furnace core}And (6) carrying out temperature compensation.

S306, according to the set temperature T_{Setting up}And compensated core temperature T_{Core compensation}Determining the heating power P of a heating pipe;

in order to improve the working efficiency of the electric oven, when T_{Setting up}-T_{Core compensation}Not less than 30 ℃, that is, the temperature of the furnace core is far from the set temperature, at this time, in order to reduce the preheating time, increase the temperature rise speed, and prolong the service life of the relay for controlling the on-off of the heating tube in the electric oven, the embodiment preferably controls the heating tube to heat at a preset fixed heating power (for example, rated power), so that the temperature of the furnace core can be quickly close to the set temperature. When the temperature of the furnace core rises to reach T_{Setting up}-T_{Core compensation}<At 30 ℃, in order to improve the stability of the core temperature near the set temperature and reduce the fluctuation, the present embodiment preferably calculates the heating power P of the heating tube by using an incremental PID algorithm, and the calculation method is as follows:

since the discrete PID expression is:

heating power at the kth sampling time:

the k-1Heating power at sampling time:

therefore, the incremental PID control algorithm is formulated as:

wherein e is_kTo set a temperature T_{Setting up}Compensating temperature T of furnace core at kth sampling moment_{Core compensation}The temperature difference of (a); e.g. of the type_k-1To set a temperature T_{Setting up}The furnace core compensation temperature T at the k-1 sampling moment_{Core compensation}The temperature difference of (a); e.g. of the type_k-2To set a temperature T_{Setting up}The furnace core compensation temperature T at the k-2 sampling moment_{Core compensation}The temperature difference of (a); k is a radical of_p、k_i、k_dIs a control coefficient. Thus, the increment Δ P can be calculated_kThe value of (c).

Using calculated delta P_kAnd heating pipe power P calculated at the k-1 th sampling moment_k-1The heating pipe power P at the kth sampling moment can be calculated_kNamely: p_k＝P_k-1+ΔP_k。

For the control coefficient k_p、k_i、k_dThe value of (a) is related to the heating pipe of the electric oven, the material and the heat dissipation capacity of the electric oven and the working mode of the electric oven. Different electric ovens with control parameter k_p、k_i、k_dThe values of the coefficients are different, and the coefficients can be used for obtaining stable and reliable values through multiple experiments. As a preferable scheme of the embodiment, k may be set when the electric oven is operated in the fermentation mode_p＝4.8、k_i＝0.6、k_d4.8; when the electric oven works in other modes, k can be set_p＝4.8、k_i＝0.4、k_d＝4.4。

In the embodiment, the heating power P of the heating pipe is calculated by adopting a PID algorithm, so that the electric oven has the advantages of quick temperature rise, stable temperature maintenance, small variation amplitude and the like.

S307, adjusting the heating power of the heating pipe to be P;

and controlling the heating tube (especially the upper heating tube) to heat according to the calculated heating power P.

And S308, when the heating time of the electric oven reaches the set heating time, controlling the heating pipe to be powered off, stopping the electric oven, and entering a standby state.

In the embodiment, the compensated core temperature is used for replacing the actual core temperature, and the heating power of the heating pipe is determined by combining the set temperature, when the environmental temperature is higher, because the compensated core temperature is lower than the actual core temperature, when the temperature control of the electric oven is stable, the actual core temperature is closer to the set temperature because the actual core temperature is higher than the compensated core temperature due to the fact that the compensated core temperature is slightly lower than the set temperature due to the fact that the ring temperature causes the temperature of the electric oven to be lower than the set temperature. On the contrary, when the ambient temperature is lower, the compensated core temperature is higher than the actual core temperature, so that when the temperature control of the electric oven is stable, the actual core temperature is closer to the set temperature due to the fact that the actual core temperature is lower than the compensated core temperature under the condition that the compensated core temperature is slightly higher than the set temperature due to the environment temperature. Therefore, the actual temperature of the core of the electric oven is closer to the set temperature and is more stably stabilized on the set temperature, and the temperature control accuracy of the electric oven is improved.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.

Claims

1. A temperature control method of an electric oven, which is characterized in that,

obtaining ambient temperature T_{Environment(s)}；

According to the ambient temperature T_{Environment(s)}Determining a temperature compensation coefficient T_Compensation；

In the working process of the electric oven, the temperature T of the furnace core of the electric oven is detected regularly_{Furnace core}And using said temperature compensation coefficient T_CompensationFor the temperature T of the furnace core_{Furnace core}Performing compensation;

according to the set temperature T_{Setting up}And compensated core temperature T_{Core compensation}Determining the heating power P of a heating pipe;

adjusting the heating power of a heating pipe in the electric oven to be P;

wherein, at the acquisition ambient temperature T_{Environment(s)}In the process, the method comprises the following steps:

detecting the current temperature T0 of the electric oven when the electric oven is powered on and started;

reading the latest N times of environmental temperature values stored in a memory of the electric oven, and sequentially defining the environmental temperature values as T1 and T2 … … TN according to time sequence;

calculating the average value Tave of T1 and T2 … … TN;

if T0<Tave- △ T1, then T_{Environment(s)}Replacing T1 and T2 … … TN with T0, and clearing the temperature value stored in the temporary storage position in the memory; reserving N-1 temporary storage positions in the memory, wherein the temporary storage positions are used for storing sampling temperature values which can not be determined whether the sampling temperature values are the ambient temperature or not in the using process of the electric oven;

if the Tave- △ T1 is not less than T0 is not less than Tave +. △ T1, then T_{Environment(s)}(T2+ … … + TN + T0)/N, and recording T0 as the latest ambient temperature value, and forming the latest N ambient temperature values with the T2 … … TN;

if T0> Tave + △ T1, T0 is compared with the average value Tb of the temperature values stored in the temporary storage location of the memory:

if T0>Tb + △ T2, then T_{Environment(s)}T0 is discarded;

if Tb- △ T2 is not less than T0 is not less than Tb + deltaT 2 and N-1 temperature values are stored in the temporary storage position, then T_{Environment(s)}The average value of the N-1 temperature values and the T0 is equal, the N-1 temperature values and the T0 are used as environment temperature values of the last N times, the T1 and the T2 … … TN are replaced, and the temperature values on the temporary storage positions in the memory are cleared; if the temperature values stored in the temporary storage position are less than N-1, T_{Environment(s)}Tave and save T0 in the temporaryStoring the position;

if T0<Tb- △ T2, then T_{Environment(s)}Tave, and if the temperature value stored in the temporary storage position is less than N-1, storing T0 in the temporary storage position; if N-1 temperature values are stored in the temporary storage position, discarding the temperature value written into the temporary storage position at the earliest time, and storing T0 in the temporary storage position;

the △ T1 and the △ T2 are constants.

2. The method of controlling temperature of an electric oven according to claim 1, wherein the compensated core temperature T is_{Core compensation}It should satisfy:

at T_{Environment(s)}<At 25 ℃ T_{Core compensation}Greater than the actual core temperature T_{Furnace core}And the lower the ambient temperature is, the temperature compensation coefficient T_CompensationThe larger;

at T_{Environment(s)}>At 25 ℃ T_{Core compensation}Less than the actual core temperature T_{Furnace core}And the higher the ambient temperature is, the higher the temperature compensation coefficient T_CompensationThe smaller.

3. The method of controlling temperature of an electric oven according to claim 2, wherein the temperature is controlled according to an ambient temperature T_{Environment(s)}And temperature compensation coefficient T_CompensationCorresponding relation between them forms a comparison table, according to the obtained environmental temperature T_{Environment(s)}Determining the ambient temperature T by searching the comparison table_{Environment(s)}Corresponding temperature compensation coefficient T_Compensation。

4. the method for controlling the temperature of an electric oven according to claim 1, wherein △ T1-3 ℃, △ T2-2 ℃, and said N-3.

5. The method of claim 1, wherein the current temperature T0 is detected and converted by a sensor of the electric oven for detecting the temperature of the core, and is detected only once when the electric oven is powered on.

6. The method of controlling the temperature of an electric oven according to any one of claims 1 to 5, wherein the process of determining the heating power P of the heating tube comprises:

when T is_{Setting up}-T_{Core compensation}When the temperature is more than or equal to 30 ℃, controlling the heating pipe to heat at a preset fixed heating power;

when T is_{Setting up}-T_{Core compensation}<At 30 ℃ according to T_{Setting up}And T_{Core compensation}The heating power of the heating tube is calculated by adopting the following formula:

P_k＝P_k-1+ΔP_k；

ΔP_k＝k_p(e_k-e_k-1)+k_ie_k+k_d(e_k-2e_k-1+e_k-2)；

7. The method of controlling temperature of an electric oven according to claim 6,

when the electric oven works in the fermentation mode, k is set_p＝4.8、k_i＝0.6、k_d＝4.8；

When the electric oven is operated in a mode other than fermentation, k is set_p＝4.8、k_i＝0.4、k_d＝4.4。

8. An electric oven, comprising:

a temperature sensor for detecting a core temperature T of the electric oven_{Furnace core}And is used for detecting the current temperature T0 of the electric oven when the electric oven is powered on and started up;

a storage for storing an ambient temperature of the electric oven when recently used;

a controller for determining the current ambient temperature T0 according to the ambient temperature stored in the memory and the current temperature T0 detected by the temperature sensor when the electric oven is powered on and started_{Environment(s)}And according to said ambient temperature T_{Environment(s)}Determining a temperature compensation coefficient T_Compensation(ii) a In the working process of the electric oven, the controller detects the temperature T of the furnace core collected by the temperature sensor at regular time_{Furnace core}And using said temperature compensation coefficient T_CompensationFor the temperature T of the furnace core_{Furnace core}Compensating for the temperature T_{Setting up}And compensated core temperature T_{Core compensation}Determining heating power P;

the heating pipe is used for heating food in the electric oven, and the heating power is P;

wherein the controller is determining the current ambient temperature T_{Environment(s)}Reading the latest N times of environmental temperature values stored in the memory, and sequentially defining the environmental temperature values as T1 and T2 … … TN according to the time sequence; calculating the average value Tave of T1 and T2 … … TN;

if T0<Tave- △ T1, then set T_{Environment(s)}Replacing T1 and T2 … … TN with T0, and clearing the temperature value stored in the temporary storage position in the memory; reserving N-1 temporary storage positions in the memory, wherein the temporary storage positions are used for storing sampling temperature values which can not be determined whether the sampling temperature values are the ambient temperature or not in the using process of the electric oven;

if the Tave- △ T1 is not less than T0 is not less than Tave +. DELTA.T 1, then set T_{Environment(s)}(T2+ … … + TN + T0)/N, and recording T0 as the latest ambient temperature value, and forming the latest N ambient temperature values with the T2 … … TN;

if T0>Tb + △ T2, then set T_{Environment(s)}T0 is discarded;

if Tb- △ T2 is not less than T0 is not less than Tb + deltaT 2 and N-1 temperature values are stored in the temporary storage position, then setting T_{Environment(s)}The average value of the N-1 temperature values and the T0 is equal, the N-1 temperature values and the T0 are used as environment temperature values of the last N times, the T1 and the T2 … … TN are replaced, and the temperature values on the temporary storage positions in the memory are cleared; if the temperature values stored in the temporary storage position are less than N-1, setting T_{Environment(s)}Tave, and storing T0 in the staging location;

if T0<Tb- △ T2, then set T_{Environment(s)}if the temperature values stored in the temporary storage position are less than N-1, T0 is stored in the temporary storage position, if N-1 temperature values are stored in the temporary storage position, the temperature value written in the temporary storage position at the earliest time is discarded, and T0 is stored in the temporary storage position, wherein △ T1 and △ T2 are constants.

9. An electric oven according to claim 8, characterized in that in said memory there is stored a temperature T according to the environment_{Environment(s)}And temperature compensation coefficient T_CompensationA look-up table formed by the corresponding relation between the temperature and the ambient temperature, and the controller is used for controlling the temperature according to the current ambient temperature T_{Environment(s)}Determining the ambient temperature T by searching the comparison table_{Environment(s)}Corresponding temperature compensation coefficient T_Compensation。