Patent Publication Number: US-10312732-B2

Title: System and method for device identification

Description:
BACKGROUND OF THE INVENTION 
     Most kitchens have a plethora of appliances and devices for food preparation. For example, a kitchen may have a toaster, a coffee maker, a mixer, a blender, a food processor, and a stove. Most of these devices are or could be electric powered. 
     Often, these devices are used at different locations throughout the kitchen. The electric appliances must be located near outlets. Although greatest ergonomics is achieved if these appliances were used near the stove, the cords for these appliances generally must be kept away from the cooking surface of the stove. 
     The cords of these appliances also complicate the usability of these appliances. For example, a cord for a mixer must allow the cook to use the mixer in a variety of positions. If the cord is too long, the cord creates clutter in the kitchen, and reduces the available counter top space for food preparation. 
     The stove presents other challenges to kitchen ergonomics. Generally, the stove top can be used only for cooking. Thus, a segment of countertop space within a kitchen is unusable. 
     Some cooking surfaces have the heating element beneath a heat conductive material. While this does provide additional countertop space, the heat conductive material does provide some insulation, thereby reducing the overall efficiency of the stove. Due to the heating of the conductive material, some cooks find such a stove top difficult to use. 
     An improved method of providing power to the variety of appliances within a kitchen is therefore highly desirable. 
     SUMMARY OF THE INVENTION 
     A food preparation system includes a non-contact power transfer system for transferring power to a cooking appliance. A communication system allows information regarding a cooking appliance placed in proximity to the non-contact power transfer system to be provided to a control system. The control may send information to the cooking appliance. The non-contact power transfer system could be an inductive power system. 
     Using the information from the appliance, the control can determine the amount of energy to be transferred to the appliance in order for the appliance to achieve a desired result. For example, if the cooking appliance were a frying pan and it was desired for the pan to be heated to 250° F., the control calculates the energy required to heat the pan to the desired temperature as well as the time required for the frying pan to reach the desired temperature. If the frying pan included a temperature sensor, the frying pan would provide the temperature to the control, thereby allowing a closed loop control system for the frying pan. 
     In another embodiment, if the appliance did not have a communication system, the type of appliance could be detected by way of the frequency response profile for the appliance. The frequency response profile is a plot of the energy transferred to the appliance at different frequencies of operation by the non-contact power transfer system. To create the frequency response profile, the non-contact power transfer system is operated at many different frequencies. The energy transferred to the appliance is determined for each frequency. Each appliance has a unique frequency response profile, thereby allowing the appliance to be accurately identified. Once identified, information regarding the operation of the appliance is accessed from a database containing many different appliances. 
     If the appliance had a communication system, information regarding the operation of the appliance would be provided to the control by downloading information from the appliance to the control system. Alternatively, the appliance could provide an identifier to the control, and then the control would access information regarding the operation of the appliance from a memory. 
     The food preparation system may be connected to a network, allowing a user to provide control information to the food preparation system from a remote location. A user would then be able to provide precise control to various appliances in use with the food preparation system. 
     The food preparation system may also include alignment means such as a magnet to maintain the appliance in an acceptable position relative to the non-contact power system. 
     Various appliances could be used with the food preparation system. For example, an appliance could include a user interface for programming the operation of the appliance and the control system. Such an appliance includes a food container, a communication system, and a user input device. A user programs the operation of the appliance by entering specific cooking information such as temperature and time, or a user could select a preprogrammed cooking schedule. 
     Once entered, the appliance when placed in proximity to the non-contact power system would transfer the information regarding the cooking schedule to the control. The control would then power the appliance in accordance with the schedule. 
     Because energy is transferred to the appliance by way of a non-contact power system, a cooking appliance and control system could be fully sealed in a single unit. The entire appliance could then be immersed or place in a dish washer without worry of harming the control or the power connection. 
     A less complex appliance, such as a toaster, could also be used with the food preparation system. A toaster would include heating elements which would be inductively heated by the non-contact power system. A transmitter would provide information regarding the toaster to the control system. 
     These and other objects, advantages and features of the invention will be more readily understood and appreciated by reference to the detailed description of the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a food preparation system. 
         FIG. 2  is a top view of the food preparation system. 
         FIG. 3  shows an inductively powered appliance. 
         FIG. 4  shows an active cooking device. 
         FIG. 5  shows an alternative embodiment of an active cooking device. 
         FIG. 6  shows an inductively powered toaster. 
         FIG. 6A  shows an independent secondary heater for a cooking device. 
         FIG. 7  shows an interface unit for an inductive cooking appliance 
         FIG. 8  shows a method for operating the inductive cooking system. 
         FIG. 9  shows a frequency profile for an inductively powered appliance. 
         FIG. 10  is a state diagram for the inductive cooking system. 
         FIG. 11  shows the control algorithm for the system. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a food preparation system  8  for use within a kitchen. Communication interface  10  is attached to antennas  12 ,  14 ,  16 . Communication system  10  is shown to be directly connected to antennas  12 ,  14 ,  16 . Communication system  10  could be a wireless communication system using Blue Tooth, 802.11b, 802.11g or any other proprietary or open wireless communication protocol. Power supply  17  is connected to primary coils  18 ,  20 ,  22 . 
     Power supply  17  preferable is an adaptive inductive power supply such as the one described in U.S. Pat. No. 6,825,620, issued Nov. 30, 2004 to Kuennen et al., the subject matter of which is incorporated in its entirety by reference. Primary coils  18 ,  20 ,  22  inductively couple to cooking utensils  24 ,  26 ,  28  in order to provide power to the utensils. 
     Cooking utensils  24 ,  26 ,  28  are powered by power supply  17  in cooperation with primary coils  18 ,  20 ,  22 . Countertop  30  could be composed of any of the common materials used for kitchen countertops, such as Formica® or granite. If needed, insulating layer  32  may be used to provide thermal and electrical isolation of cooking utensils  24 ,  26 ,  28  from countertop  30 . User interface  34  allows a user to input and view information from controller  36  to control the operation of food preparation system  8 . 
     Countertop  30  or insulation layer  32  could include alignment means  43 ,  45 ,  47  further comprising electro or permanent magnets located near the center of each primary coil  18 ,  20 ,  22 . Appliances  24 ,  26 ,  28  could include permanent magnets located near the center of each respective secondary, and oriented such that the secondary magnets serve to align the center of the appliance  24 ,  26 ,  28  secondary with the center of primary coil  18 ,  20 ,  22 . Alternatively, alignment means  43 ,  44 ,  45  could be comprised of a visual indicator, such as a colored spot, an indentation, a raised section, a pin, or a recess. 
     Controller  36  includes processor  38  and memory  39 . Processor  38  could be a microcontroller like the PIC30F3011, manufactured by Microchip, Inc., of Chandler, Ariz. 
     Power measurement system  37  could be a single phase bi-directional power/energy integrated circuit such as the CS5460A manufactured by Cirrus Logic of Austin, Tex. Power measurement system  37  measures the input voltage and current from an external power source. Controller  36  periodically polls power measurement system  37  to determine the power, current and voltage being supplied to food preparation system  8 . 
     Controller  36  also monitors any devices drawing power from food preparation system  8  as well as controls the operation of power supply  18 . Controller  36  also monitors the current supplied to primary coils  18 ,  20 ,  22 . 
     Controller  36  also provides a safety shutoff. If the current supplied to any one of the primary coils  18 ,  20 ,  22  exceeds a threshold current, then power to the primary coils is reduced or eliminated. 
     Communication interface  10  could also be connected to network  27  and then to personal computer  29 . A user could use personal computer  29  to access the operation of food preparation system  8 . 
     Due to the possibility of a high electromagnetic field, controller  36  monitors the wireless output of communication interface  10 . If the frequency of the output is not within the correct frequency region, the wireless communication is disabled. After a period of time, controller  36  would again attempt to establish a wireless communication link with any appliance. 
       FIG. 2  is a top view of food preparation system  8  shown in  FIG. 1 . Temperature sensors  40 ,  42 ,  44  provide information regarding the temperature of the surface to control  34 . Keypad  46  and display  48  allow the user to view information regarding cooking utensils  24 ,  26 ,  28 . Additionally, keypad  46  allows the user to send commands to food preparation system  8 . Magnets  43 ,  45 ,  47  assist in maintaining an appliance in alignment with coils  18 ,  20 ,  22 . 
       FIG. 3  shows a passive heating device for use with food preparation system  8 . Devices for use with food preparation system  8  generally fall into three categories: passive heating devices; active heating devices; and electro-mechanical devices, such as blenders, mixers, electric can openers, and other electrical appliances. 
     Frying pan  50  is an example of a passive heating device. When placed near frying pan  50 , a primary of food preparation system  8  when energized creates circulating currents within the base of frying pan  50 , and thus heats the base of frying pan  50 . 
     Controller  36  could identify frying pan  50  from the resonant frequency signature of frying pan  50 . It has been found that each load has a slightly different frequency characterization. Processor  38  can use the information regarding the frequency response to retrieve information regarding the frying pan or any utensil. For example, processor  38  could provide to the user the manufacturer of frying pan and the various heating requirements for the frying pan. 
     Memory  39  could include information relating to the cooking characteristics of frying pan  50 . For example, memory  39  could contain the heating curves for frying pan  50 , identifying the current required of the primary to heat frying pan  50  to a temperature. This would allow a user to program a desired temperature for frying pan  50 . Controller  36  would then determine the most efficient method to bring frying pan  50  to the desired temperature as well as to maintain frying pan  50  at the desired temperature. Such a sequence could involve providing power to frying pan  50  at different current levels and different frequencies over a period of time. 
     A temperature sensor could provide additional data to controller  36  to thus provide very fine control over the cooking temperature within frying pan  50 . A user could enter a recipe or a temperature/time sequence by way of keypad  46  and display  48 , and thus have the energy supplied to frying pan  50  vary over a cooking cycle. 
     Instead of detecting the resonant frequency of frying pan  50  to identify frying pan  50 , frying pan  50  could include RFID tag  52 . RFID tag  52  contains information identifying frying pan  50 . RFID tag  52  could include an identifier. Processor  38  would look up information regarding frying pan  50  from memory  39 . RFID tag  52  may contain specific information regarding the heating requirements of frying pan  50 . If RFID tag  52  included specific information regarding the heating requirements of frying pan  50 , then the information would be used directly by processor  38  to control the heating of frying pan  50 . RFID tag  52  could be a transponder, a WIFI transmitter, or any other device for transmitting information to controller  36 . 
       FIG. 4  shows an active cooking device  58 . Food container  60  is placed above and in contact with heating mass  62 . Heating mass  62  is positioned near or on countertop  64 . Device control  70  includes display  66  and keypad  68 . Keypad  68  could be a series of switches or knobs. Device control  70  provides a way to monitor and control the temperature within food container  60 . For example, display  66  could show the temperature within food container  60 . Transceiver  72  provides two way communication between device control  70  and controller  74  by way of communication interface  76 . Antenna  78  is located proximal to countertop  64  to facilitate communicate between transceiver  72  and communication interface  76 . Temperature sensor  81  provides information regarding the surface temperature of countertop  64 . 
     In operation, a user inputs the desired temperature or temperature schedule of food container  60  by way of device control  70 . Device control  70  then sends information regarding the desired temperature and current temperature of food container  60  to controller  74  by way of transceiver  72 . Controller  74  adjusts the power supplied by power supply  82  to primary  80 , thus allowing accurate control of the temperature within food container  60 . 
     Various modifications of active cooking device  58  are possible.  FIG. 5  shows one such version of cooking device  58 . Cooking tray  83  has food area  85 . Food can be placed within food area  85  for heating. A heating mass is located below food area  85 . Display  84  could display date, time, elapsed time and temperature within food area  85 . Device control  86  consists of a simple “up-down” switch for increasing or decreasing the temperature within food area  85 . 
     Cooking tray  83  could be totally encapsulated in a moisture resistance material, thus allowing the cooking tray  83  to be fully immersible in water for cleaning. Additionally, the encapsulating material could allow cooking tray  83  to be placed within an oven or other baking device. 
       FIG. 6  shows a toaster for use with food preparation system  8 . Sidewalls  90 ,  92  contain two heat conducting members  94 ,  96 . Heating element  93  receives energy from the primary winding, and begins to heat, which causes heat conducting members  94 ,  96  to heat. Switch  98  allows the selection for the darkness of the bread by way of timer  100 . Timer  100  is set to a predetermined length of time. When timer  100  expires, a signal is sent from transceiver  102  to turn off the primary winding. 
       FIG. 6A  shows independent secondary heater  110  for the system for use with food preparation system  8 . Independent secondary heater  110  allows for the use of non-magnetic pots and pans with food preparation system  8 . 
     Independent secondary heater  110  includes a secondary section  112  and a scale section  114 . Secondary section  112  is heated by way of a primary within food preparation system  8 , and thereby can heat glass or other non-metallic cookware. The scale section is used to detect the weight of any items placed on independent secondary heater  110 . Independent secondary heater  110  could include a transceiver for sending and receiving information to food preparation system  8 . 
       FIG. 7  shows interface unit  130  for an inductive cooking appliance. Interface unit  130  includes processor  132 , memory  134 , input device  136 , inductive secondary  138 , transceiver  140 , and display  142 . Interface unit  130  may be installed on an inductive cooking appliance or could be constructed as part of the inductive cooking appliance. 
     Input device  136  allows a user to enter an operating parameter, such as the desired temperature or motor speed, for an inductive cooking appliance. Input device  136  could be a keypad, dial, switch, or any other mechanism allowing for entry and control of the inductive cooking appliance. 
     Memory  134  contains an identifier for the cooking appliance as well as the operating parameters. Processor  132  by way of transceiver  140  provides instructions and information to processor  38  so that processor  38  can control the power provided to the respective primary coil. Processor  132  monitors the actual secondary coil voltage and the target voltage and requests changes in the frequency. The secondary coil voltage is observed at a rate of approximately 500K samples/sec. The sample rate could be more or less than 500K samples per second. 
     Memory  134  could also contain a profile for the cooking appliance, such as a heating profile. Thus, processor  132  could instruct processor  38  to provide sufficient power to rapidly heat the cooking appliance, and then reduce the power provided to the cooking appliance as the temperature of the cooking appliance approached the desired temperature. 
     Transceiver  140  could be use RFID, Bluetooth, WIFI, or any other wireless method to communicate information to processor  38 . Processor  132  could be a PIC30F3010 microcontroller, also manufactured by Microchip, Inc., of Chandler, Ariz. 
       FIG. 8  shows a method for operating the inductive cooking system. 
     Inductive cooking system  8  periodically energizes each primary not in use. Step  200 . Preferably, the primary is energized a probe frequency. The probe frequency preferably is not the resonant frequency of any inductive appliance. 
     The system then determines whether a load was detected by the probe frequency. Step  202 . If no load was detected, the process of periodically providing power at a probe frequency continues. 
     If a load is present and if the system uses an adaptive inductive power supply, the frequency of the operation of the adaptive inductive power supply shifts from the probe frequency, thereby indicating to controller  36  that a load is present. If a load is detected, controller  36  then continually energizes the respective primary at a start frequency. Step  204 . 
     The start frequency could be the same as the probe frequency or it could be a different frequency. The energization of the primary at the start frequency provides sufficient power to power any communication system on the cooking appliance, providing power to  138  inductive secondary and thereby to transceiver  140 . When transceiver  140  is powered up, it begins transmitting information. 
     Inductive cooking system  8  then checks for any response from inductive appliance  130 . Step  206 . 
     If no response is received, inductive cooking system  8  then performs a characterization analysis of the device. Step  208 . Characterization could consist of energizing or driving the primary at a plurality of frequencies to obtain a frequency profile. A frequency profile is shown in  FIG. 9 . 
     In order to create a frequency profile, the frequency of the power supply is varied over a frequency range. The output voltage at each frequency is then determined. Each type of appliance has a unique frequency profile. Thus, by examining the frequency profile, the type of appliance placed into proximity to the food preparation system can be determined. 
     Returning to  FIG. 8 , after the appliance has been characterized, the system determines whether the device matches any known device. Step  210 . If the characterization matches any known device, the identifier for that device is retrieved. Step  214 . 
     If the characterization does not match any device, the system operates in manual mode. Step  211 . Manual mode allows a user manually adjusting the power supplied to the appliance by way of user interface  34 . 
     If a response is received, then a communication link is established. Step  212 . The appliance identifier is then obtained. Step  214 . 
     The operating parameters for the device are obtained. Step  216 . The power system then is energized in accordance with the operating parameters. Step  218 . 
       FIG. 10  is a state diagram for the controller  36  for one of primary coils  18 ,  20 ,  22  when an inductive appliance with a communication interface is used. During S_Probe_Inactive  170 , the interval between probes has not elapsed. There is no known load and no communication with an external device. The coil is therefore not energized. S_Probe_Wait  172  occurs when the interval between probes has elapsed. There is no known load, the coil is not energized and there is no communication. 
     S_Probe_Active  174  occurs during the probe. Controller  36  is determining whether a load is present. The coil is energized at a probe frequency. A poll is sent by communication interface  10  to any appliance. If a return response is not received, the system returns to S_Probe_Inactive  170 . If a reply is received, then the system progresses to S_Feedback  178 . (See time delay  176 ). 
     In S_Feedback  178 , a load is found and identified. The coil is energized as a variable frequency by a closed-loop feedback. The communication link provides periodic feedback to controller  36 . 
     As shown by time delay  180 , if a communication reply is not received during S_Feedback  178 , then the system reverts to state S_Probe_Inactive  170 . 
       FIG. 11  shows the control algorithm for the system. All tasks except those within box  200  are performed by processor  132 . The target voltage V target  is compared with V out . A frequency change (Δf) is computed and sent to controller  36 . Controller  36  modifies the drive frequency, producing a different induced voltage V out(t) . This then is fed back into the original input in order to complete the closed loop feedback system. Minor variations between V target  and V out  may be ignored. 
     The initial primary frequency could be any frequency. However, it has been found satisfactory to use the probe frequency. One suitable frequency is 80 KHz. Referring again to  FIG. 9 , a change in the frequency causes a change of the voltage induced in the secondary coil. 
     Before any changes in frequency occur, a small adjustment in frequency is made to determine whether the voltage slope is either positive or negative for the change in frequency. The slope indicates whether the frequency is increased or decreased in order to change the output voltage. For example, referring to  FIG. 9 , if the initial frequency of the primary were 50 KHz, an increase frequency would increase the output voltage, while a decrease in frequency would decrease the output voltage. However, if the initial frequency of the primary were 80 KHz, then a decrease in frequency would create an increase in output voltage, while an increase in frequency would produce a decrease in output voltage. 
     In some situations, a particular inductive appliance may have a frequency trough. A frequency trough is a minimum where the voltage output cannot be reduced by either increasing or decreasing the frequency. In this situation, after a predetermined number of attempts to change the voltage fail, the frequency of the primary is shifted by a predetermined amount to a new frequency. The predetermined amount of the frequency shift is sufficient to move the operating frequency from the frequency trough. 
     Generally, communication between controller  36  and any cooking utensil is commenced by controller  74  sending queries. The cooking utensils respond to the queries. Alternatively, the cooking utensils could broadcast information to controller  74 . 
     The above description is of the preferred embodiment. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any references to claim elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular.