Patent Application
20230393596
The present subject matter relates generally to methods for transitioning between power levels in appliances, particularly cooking appliances.
Cooking appliances frequently include heating elements that can be cycled on and off, such as electrical heating elements and gas burners. Such heating elements can be cycled on or off during operation depending on the amount of heating power needed by the cooking cycle. Typically, the power is controlled with a predefined frequency or period. During the cycle period, the ratio of the time the heating element is on versus the total time can be changed to produce different power levels. This ratio of time on to total time is commonly referred to as the duty cycle.
Whenever the user or the cooking algorithm operating the cooking appliance calls for a change in power level, the duty cycle of the heating element can be changed. In an open-loop cooking (OLC) scenario, the user could manually change the power level as desired during the cooking cycle. Similarly, during cooking in a closed-loop cooking (CLC) scenario, the power level change can occur at any time during the power cycle, during either the on or off portions of the duty cycle. This can cause back-to-back on or off portions of the duty cycle, extending the amount of time the heating element remains in that state.
Aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.
In one example embodiment, a method of operating a cooking appliance includes initiating, at a controller, a cooking operation at a first duty cycle. Determining, by the controller, a power level change. Comparing, at the controller, the first duty cycle to a second duty cycle of the power level change. Determining, by the controller, a state of the first duty cycle that comprises one of an on semi-cycle and an off semi-cycle, a passed time of the first duty cycle, and a new time of the second duty cycle. Calculating, by the controller, an additional time of the first duty cycle by subtracting the passed time of the first duty cycle from the new time of the second duty cycle. Then adjusting, at the controller, the power level change and the state of the second duty cycle in response to the additional time passing.
In another example embodiment, a method of operating an appliance includes, initiating, at a controller, an operation at a first duty cycle. Determining, by the controller, a power level change. Comparing, at the controller, the first duty cycle to a second duty cycle of the power level change. Determining, by the controller, a state of the first duty cycle that comprises of an on semi-cycle and an off semi-cycle. Then adjusting, at the controller, the power level change and the state of the second duty cycle in response to the completion of the state of the first duty cycle.
In another example embodiment, a method of operating an appliance during a duty cycle includes initiating, at a controller, a first duty cycle. Determining, by the controller, a power level change. Comparing, at the controller, the first duty cycle to a second duty cycle of the power level change. Determining, by the controller, a state of the first duty cycle that comprises one of an on semi-cycle and an off semi-cycle, a passed time of the first duty cycle, and a new time of the second duty cycle. Calculating, by the controller, an additional time of the first duty cycle by subtracting the passed time of the first duty cycle from the new time of the second duty cycle. Then adjusting, at the controller, the power level change and the state of the second duty cycle in response to the additional time passing.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. For example, the approximating language may refer to being within a ten percent (10%) margin. Similarly, a state of operation modified by the term “semi-cycle” is not meant to be limited to exactly half of a cycle, as the “semi-cycle” may be more or less than half of the cycle.
Referring now to the figures,
Cooktop appliance 100 includes a ceramic plate 110 for supporting cooking utensils, such as pots or pans, on a cooking or top surface 114 of ceramic plate 110. Ceramic plate 110 may be any suitable ceramic or glass plate. Heating assemblies 122 are mounted below ceramic plate 110 such that heating assemblies 122 are positioned below ceramic plate 110, as would be understood in the art. Ceramic plate 110 may be continuous over heating assemblies 122.
While shown with four heating assemblies 122 in the example embodiment of
Cooktop appliance 100 may be controlled by a control board or controller 140. Controller 140 may be in communication (via for example a suitable wired or wireless connection) to components of cooktop appliance 100, such as heating assembly 122. By way of example, controller 140 may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of cooktop appliance 100. The memory may be a separate component from the processor or may be included onboard within the processor. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH.
A user interface 130 provides visual information to a user and allows a user to select various options for the operation of cooktop appliance 100. For example, displayed options can include a desired heating assembly 122, a desired cooking temperature, and/or other options. User interface 130 can be any type of input device and can have any configuration. In
In the example embodiment shown in
Heating assembly 122 of cooktop appliance 100 may be cycled between an on semi-cycle and an off semi-cycle. The power to heating assembly 122 may be cycled during a cooking operation depending on the amount of heating power, otherwise known as the power level, that is needed by the cooking operation. Generally, the power may be controlled with a predefined frequency/period. During this cycle period, the ratio of the on semi-cycle time versus the total period time may be changed to produce different power levels, and the ratio may be called a duty cycle. Whenever a user or a cooking algorithm calls for a power level change, the duty cycle of heating assembly 122 may be changed. The duty cycle may start with the on semi-cycle. Generally, cooking appliances, such as cooktop appliance 100, have a predefined duty cycle period, i.e., in the present example embodiment the duty cycle is twenty seconds (20 s) during normal open-loop control (OLC) with no temperature feedback. The user may manually change the level as desired during the cooking operation, and thus, the power level change can occur at any time during the duty cycle period.
During closed-loop control (CLC), a user may set a desired cooking temperature, and an appliance algorithm adjusts the power level during the cooking operation based upon sensor feedback. In CLC, like in OLC, the cooking algorithm can change the power level at any time during the duty cycle period. Since the change to a new power level in both OLC and CLC is not always synchronous with the duty cycle, known appliances restart the duty cycle immediately when the change in power level is requested, i.e., the current duty cycle may be cut short in either the on semi-cycle or the off semi-cycle. This immediate response may cause back-to-back on or off semi-cycles, extending the amount of time in either the on semi-cycle or the off semi-cycle. This results in power and temperature deviations from expected values.
Referring now to
If a power level change is determined, at 330, controller 140 may compare the first duty cycle of the current power level, to a second duty cycle of the power level change. In response to the second duty cycle, at 340, controller 140 may determine the state of the current power cycle, i.e., whether the first duty cycle is in one of the on or off semi-cycle. In addition to the state of the current power cycle, at 340, controller 140 may also determine a passed time of the first duty cycle, i.e., how much time has occurred while in the current state, and a new time of the second duty cycle, i.e., how much time the second duty cycle spends in the current state. At 350, controller 140 may calculate an additional time of the first duty cycle by subtracting the passed time of the first duty cycle from the new time of the second duty cycle. This is best shown in
At 360, controller 140 may adjust the power level change and the state of the second duty cycle in response to the additional time passing. The change of the state of the second duty cycle may be opposite to the state of the first duty cycle (on to off, or off to on). At 342, the dashed line indicates a scenario where the passed time of the first duty cycle may be greater than or equal to the new time of the second duty cycle, thus calculating additional time at 350 may not be necessary and method 300 may go directly from 340 to 360. Method 300 may be repeated for any further power level changes.
For example, in a scenario where in an on semi-cycle and the passed time of the first duty cycle is greater than or equal to the new on time of the second duty cycle, controller 140 may adjust the power level change and start the second duty cycle in the off semi-cycle. In another scenario where in the on semi-cycle and the passed time of the first duty cycle is less than the new on time of the second duty cycle, controller 140 may calculate and extend the time of the on semi-cycle until the time of the on semi-cycle matches the new on time of the second duty cycle. Then, controller 140 may adjust the power level change, starting in the off semi-cycle.
Method 300 may also apply in scenarios where the first duty cycle is in the off semi-cycle. In a scenario where the first duty cycle is in the off semi-cycle and the passed time is greater than or equal to the new off time, controller 140 may adjust the power level change and start the second duty cycle in the on semi-cycle. In another scenario where in the off semi-cycle and the passed time of the first duty cycle is less than the new off time of the second duty cycle, controller 140 may calculate and extend the time of the off semi-cycle until time of the off semi-cycle matches the new off time of the second duty cycle. Then, controller 140 may adjust the power level change, starting in the on semi-cycle.
Referring again to
Shown in
If a power level change is determined, at 430, controller 140 may compare the first duty cycle of the current power level, to a second duty cycle of the power level change. In response to the second duty cycle, at 440, controller 140 may determine the state of the current power cycle, i.e., the first duty cycle is in one of the on or off semi-cycle. Controller 140 may then wait until the end of the current on or off semi-cycle before at 450 adjusting to the second duty cycle, starting in the opposite semi-cycle of the current on or off semi-cycle.
To better illustrate the benefits of method 300,
Supplemental to the example plot provided in
Other example embodiments may exist wherein the algorithm may wait until the end of the current power cycle (e.g., twenty (20) seconds) before adjusting to the new power level with the second duty cycle. This example embodiment may be less ideal than method 300. For instance, the power level change may not take effect as quickly and could cause a delayed response in situations that could be as long as the power cycle period, i.e., twenty seconds (20 s). Another example embodiment may exist wherein a CLC system may have a sampling time equal to the power cycle period. The sampling time in CLC is a length of time between temperature readings and power level changes. In this example embodiment, a new power level would be requested exactly at the start of a new power cycle, thus preventing back-to-back on or off semi-cycles. However, this example embodiment may reduce the accuracy of the CLC cooking algorithm.
Each embodiment of the present disclosure may be used in cooking appliances during power level changes and duty cycling, or in any appliance, with any parameter where the duty cycle is changed at any time during operation.
As may be seen from the above, the present disclosure may provide a method or methods of operating an appliance in order to avoid back-to-back on or off semi-cycles, i.e., prolonged time in the on or off semi-cycles resulting in temperatures and power levels different than desired. Thus, overall, the disclosed methods may result in better power and temperature control, reduced power and temperature errors, and better cooking performance than conventional methods of operation.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
