System and method for controlling power to a heater

Abstract

The present disclosure relates to a control system for controlling a heater comprising at least one heating element.SOLUTION: The control system includes a power converter operable to provide adjustable voltage outputs to the heater, sensor circuitry to measure electrical characteristics of heater elements of the heater, a reference temperature sensor to measure a reference reference temperature at the heater, and a controller. The controller is configured to calculate a primary temperature of the heater elements based on the electrical characteristic and to determine a voltage power to be applied to the heater based on at least one of the reference temperature and the primary temperature. The controller is configured to operate in at least one of an operational mode and a learning mode and to execute a protection protocol when voltage is supplied to the heater.SELECTED DRAWING: Figure 1

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 62 / 543,457, filed August 10, 2017, and is a continuation-in-part of U.S. Application No. 15 / 624,060, entitled "Power Converter for Thermal Systems," filed June 15, 2017, which claims the benefit of U.S. Provisional Application No. 62 / 350,275, filed June 15, 2016, the contents of which are incorporated herein by reference in their entireties. [Technical Field]

[0002] The present disclosure relates to a system and / or method for controlling a thermal system having a heater. [Background technology]

[0003] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0004] Generally, a heater, such as a pedestal heater, for heating a load includes a heating element controlled by a control system. For example, a pedestal heater includes a ceramic substrate and a heating plate having multiple resistive heating elements embedded in the ceramic substrate that define multiple heating zones. Typically, the same power is applied to the multiple resistive heating elements at the same ramp rate during heater start-up.

[0005] Even when the same power is applied to the resistive heating elements, some resistive heating elements may heat up faster than others due to differences in characteristics, for example, due to the location of the heating zone relative to the heat sink and non-uniform manufacturing. When one heating zone heats up faster than an adjacent heating zone, the temperature difference between the adjacent heating zones causes differential thermal expansion, resulting in thermal stress between the adjacent heating zones. Large thermal stresses can cause thermal cracking in the ceramic substrate. These and other problems are addressed by the present disclosure. Summary of the Invention

[0006] This section provides a general summary of the disclosure and is not an all-inclusive disclosure of its entire scope or features.

[0007] In one aspect, the present disclosure relates to a control system for controlling a heater including at least one heating element. The control system includes a power converter, a sensor circuit, a reference temperature sensor, and a controller. The power converter is operable to provide an adjustable voltage output to the heater and is configured to convert a voltage input from a power source to a voltage output equal to or less than the voltage input. The sensor circuit measures an electrical characteristic of a heating element of the heater, the electrical characteristic including at least one of a current and a voltage. The reference temperature sensor measures a reference temperature of the heater. The controller is configured to operate the power converter to control the voltage output to the heater. The controller calculates a primary temperature of the heating element based on the electrical characteristic and determines a voltage output applied to the heater based on at least one of the reference temperature and the primary temperature. The controller operates in at least one of an operating mode and a learning mode and is configured to execute one or more protection protocols when the voltage output is provided to the heater.

[0008] In another form, the controller is configured to reduce or cut off power to the heater in response to a difference between the reference temperature and the primary temperature being greater than a preset threshold.

[0009] In yet another embodiment, the reference temperature sensor is one of an infrared camera, a thermocouple, and a resistance temperature detector.

[0010] In one form, in a learn mode, the controller is configured to operate the heater to generate heater-load correlation data relating the temperature of the heating element to the temperature of a load disposed on the heater.

[0011] In another form, in the learn mode, the controller is configured to gradually increase power to the heater to increase heat generated by the heater, determine a plurality of primary temperatures, and correlate the primary temperatures with respective reference temperatures detected by the reference temperature sensors to generate heater load correlation data.

[0012] In yet another aspect, the controller is configured to map the change in the primary temperature and the reference temperature over a period of time during which the power is increased.

[0013] In one form, the reference temperature sensor is configured to measure the temperature of at least one of a load disposed on the heater and a surface of the heater.

[0014] In another form, in the operating mode, the controller performs boost compensation to increase the rate at which the heating element generates heat to heat the reference to a predetermined setpoint temperature.

[0015] In yet another form, the controller is configured to determine a primary temperature of each heating element based on the electrical characteristics, and, for adjacent zones, adjust the power supplied to one or more heating elements in the adjacent zone based on the primary temperature to control temperature fluctuations across the heater.

[0016] In one form, the controller is configured to reduce power to one zone in response to the one zone having a higher temperature than a temperature of an adjacent zone.

[0017] In another aspect, in the operating mode, the controller is configured to select one state model control from among a plurality of predetermined state model controls as an operating state of the heater based on at least one of the reference temperature and the primary temperature.

[0018] In yet another form, the plurality of predetermined state model controls include at least one of a power-up control, a soft-start control, a set rate control, and a steady-state control.

[0019] In one form, each of the state model controls defines one or more operational settings for controlling the heater for the respective state model control.

[0020] In another embodiment, one or more operational settings include a transition condition that defines a condition for exiting an operational state and transitioning to another state model control.

[0021] In yet another aspect, the present disclosure is a thermal system comprising a heater and a control system as described above.

[0022] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. [Brief explanation of the drawings]

[0023] In order that the present disclosure may be fully understood, reference will now be made to the accompanying drawings, in which: FIG.

[0024] [Figure 1] FIG. 1 illustrates a thermal system having a heater and a control system according to the teachings of the present disclosure.

[0025] [Figure 2] FIG. 2 illustrates a power converter according to the teachings of the present disclosure.

[0026] [Figure 3] FIG. 3 is a block diagram of the control system of FIG.

[0027] [Figure 4] FIG. 4 is a diagram illustrating an example state model control program defined by multiple state models in accordance with the teachings of the present disclosure.

[0028] [Figure 5A]FIG. 5A shows the state model settings of the state model control program of FIG.

[0029] [Figure 5B] FIG. 5B shows the state model settings of the state model control program of FIG.

[0030] [Figure 5C] FIG. 5C shows the state model settings of the state model control program of FIG.

[0031] [Figure 5D] FIG. 5D shows the state model settings of the state model control program of FIG.

[0032] [Figure 5E] FIG. 5E shows the state model settings of the state model control program of FIG.

[0033] [Figure 6] FIG. 6 is an example of a main menu graphical user interface in accordance with the teachings of the present disclosure.

[0034] [Figure 7] FIG. 7 is a perspective view of a control system interface in accordance with the teachings of the present disclosure.

[0035] [Figure 8] FIG. 8 is a block diagram of a control system with isolation circuitry.

[0036] [Figure 9] FIG. 9 shows an example of the configuration of the separation circuit of FIG.

[0037] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. DETAILED DESCRIPTION OF THE INVENTION

[0038] The following description is merely exemplary in nature and is in no way intended to limit the disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0039] Referring to FIG. 1 , a thermal system 100 constructed in accordance with the teachings of the present disclosure includes a heater 102 and a control system 104 having a heater controller 106 and a power conversion system 108. In one embodiment of the present disclosure, the heater 102 is a pedestal heater and includes a heating plate 110 and a support shaft 112 disposed on a bottom surface of the heating plate 110. The heating plate 110 includes a substrate 111 and a plurality of resistive heating elements (not shown) embedded in or disposed along the surface of the substrate 111. The substrate 111 may be formed of ceramic or aluminum. The resistive heating elements are independently controlled by a controller 106 and define a plurality of heating zones 114, as shown by dashed lines in the figure. These heating zones 114 are merely exemplary and may have any configuration within the scope of the present disclosure.

[0040] The heater 102 may be a “two-wire” heater, in which changes in resistance can be used by the controller 106 to determine temperature. Such a two-wire system is disclosed in commonly owned U.S. Pat. No. 7,196,295, the contents of which are incorporated herein by reference in their entirety. In a two-wire system, the thermal system is an adaptive thermal system that merges the heater design with controls that incorporate power, resistance, voltage, and current into a customizable feedback control system. The feedback control system limits one or more of these parameters (e.g., power, resistance, voltage, current) while controlling the others. As described further below, in one form, the power conversion system 108 allows the controller 106 to obtain steady, continuous current and voltage readings. These readings can then be used to determine the resistance, and therefore the temperature, of the heater 102. In another form, the controller 106 is configured to measure voltage and / or current at zero crossings, as described in U.S. Pat. No. 7,196,295.

[0041] Although heater 102 is described as a pedestal heater, the control system of the present disclosure can control other types of heaters, such as tubular heaters and heater jackets for fluid lines, and should not be limited to pedestal heaters.

[0042] The control system 104 includes components, such as the controller 104, that operate at a lower voltage than the power converter 116. Therefore, to protect the low-voltage components from the high voltage, the control system 104 includes electronic components that can isolate the low-voltage components from the high-voltage components and exchange signals. In Figure 1, power lines are shown as dashed lines and data signal lines are shown as solid lines.

[0043] The power conversion system 108 includes power converters 116 (1161 to 1166 in the figure) that supply power to the heating elements of the heater 102. n) from a power source 118. IN ) is the output voltage (V OUT ), where the output voltage is less than or equal to the input voltage. An example of such a power conversion system is described in co-pending U.S. application Ser. No. 15 / 624,060, filed June 15, 2017, entitled "Power Converter for Thermal Systems," which is commonly owned with this application and its contents, and is incorporated herein by reference in its entirety. In this example, each power converter includes a buck converter operable by controller 106 to regulate a desired output voltage (V) to one or more heating elements in a given zone. OUT )

[0044] More specifically, as shown in FIG. 2 , a given power converter 116 includes a driver circuit 120 and a buck converter 122 having a control switch 124 ("SW" in the figure), also referred to as a power switch. For illustrative purposes, dashed line 126 represents the separation of the low-voltage section from the high-voltage section of the system 100. The driver circuit 202 operates the control switch 206 based on an input signal from the controller 104 to regulate the power supply 118 and output a reduced voltage to one or more heating elements 128. The driver circuit 202 includes electronics, such as optical isolators, transformers, etc., to communicate with and isolate the controller 106 from the power converter 116. Thus, the power conversion system 108 is operable to provide customizable amounts of power to each of the heating zones of the heater 102. While specific components are shown in FIG. 2 , it should be readily understood that the power converter 116 can include other components while remaining within the scope of the present disclosure.

[0045] In one form, the control system 104 includes an interlock 129, such as a relay, to control power flow between the power source 118 and the power conversion system 108. The interlock 129 is operable by the controller 106 as described in this disclosure as a safety mechanism to cut off power from the power source 118 to the power conversion system 108, and thus to the heater 102, in the event of abnormal activity.

[0046] 1 and 2 , to monitor the performance of the heater 102, the control system 104 includes a reference sensor 130 and one or more heater sensor circuits 132. The reference sensor 130 is a separate sensor configured to measure the temperature of a reference region (i.e., a reference temperature) for the heater 102. For example, in one embodiment, the reference sensor 130 measures the temperature of a load (e.g., a wafer, a pipe) being heated by the heater 102. The load is the reference region. In another example, the reference sensor 130 measures the temperature along the surface of the heater 102. The reference sensor 130 can be an infrared camera, a thermocouple, a resistance temperature detector, and / or other sensor suitable for measuring temperature. Additionally, multiple reference sensors may be used to detect different regions around the heater 102.

[0047] With the use of a two-wire heater, a heater sensor circuit 132 (i.e., sensor circuit) is configured to measure electrical characteristics of the heating element, which are then used to determine performance characteristics of the heating element, such as resistance, temperature, and other suitable information. In one embodiment, a given heater sensor circuit 132 is provided that measures the electrical characteristics of one or more heating elements that receive power from a given power converter 116. For example, FIG. 2 shows a heater sensor circuit 132 that is coupled to an electrical circuit between the power converter 116 and the heating element 128 and measures the electrical characteristics of the heating element 128. The electrical characteristics include at least one of current and voltage. In one embodiment, the sensor circuit 132 includes a power measurement chip 134 ("PM") that continuously measures the current and / or voltage regardless of the power applied to the heating element. The sensor circuit 132 may also include other electronics, such as an isolated analog-to-digital converter, an opto-isolator, or a transformer, to transmit signals between the low voltage and high voltage portions of the system. The sensor circuit 132 may be configured in other suitable ways, such as the sensor circuit described in U.S. Application No. 15 / 624,060, while remaining within the scope of this disclosure.

[0048] Data from the reference sensor 130 and / or the sensor circuit 134 is provided to the heater controller 106 for further processing to control the operation of the heater 102. In one form, the heater controller 106 is communicatively coupled to an external device, such as a user-operable computing device 136, to exchange information with the control system 104. For example, the computing device 134 may be a desktop computer, tablet, laptop, etc., and may be communicatively coupled to the controller 104 via a wireless communication link (e.g., Wi-Fi, Bluetooth, etc.) and / or wired communication. In one form, the controller 106 is configured to exchange information with the computing device 136 via one or more graphical user interfaces (GUIs). The GUIs relay information related to the control and operation of the heater 102, such as operating conditions, temperature profiles, electrical characteristics of the heater, and other suitable information, in various suitable manners. The GUI receives input from the user in a variety of suitable ways, such as set points (temperature, power, etc.), operating variables (rate of change, PID variables, etc.), and heater 102 control state selection (learn mode, calibration, manual control, state control program, etc.).

[0049] The controller 106 includes electronics including one or more microprocessors and memory (e.g., RAM, ROM, etc.) that stores computer-readable instructions (i.e., software programs) that are executed by the microprocessors. The controller 106 is configured, in accordance with the computer-readable instructions, to execute one or more control processes, such as heater learn state, state model control, system protection monitoring, and / or other suitable processes described in this disclosure.

[0050] 3 , in one form, the controller 106 is configured to operate as an interface module 200, a performance feedback module 202, a heater learning module 204, a power control module 206, a state model control module 208, a state selection module 210, and a system protection module 212. The interface module 200 is configured to communicate with one or more external devices, such as the computing device 136. With respect to the computing device, the interface module 200 is configured to display a GUI that displays to a user various control options and system performance information obtained by the other modules of the controller 106. When the user selects a control option, the interface module 200 transmits data to the respective modules of the controller 106.

[0051] The performance feedback module 202 is configured to measure the electrical responses from the reference sensor 130 and the heater sensor circuit 132 to determine a reference temperature and a heater temperature (i.e., a primary temperature in the claims). For example, based on the electrical characteristics of the sensor circuit 132, the performance feedback module 202 determines the average resistance of each heating element and then uses predetermined information correlating temperature and resistance to determine the temperature of the heating element. The performance feedback module 202 is configured to determine the reference temperature based on the type of reference sensor 130 being used. For example, if the reference sensor 130 is an RTD, the feedback module 202 includes predetermined information relating resistance to temperature and uses this information to determine the temperature of the reference region.

[0052] In one embodiment, the heater learning module 204 is configured to correlate two or more correlated parameters to form one or more types of correlation data that are then used to determine the value of one parameter based on other measurements. For example, the learning module 204 is configured to build a performance map of the heater 102 that correlates the performance of the heater 102 with the load being heated. Specifically, the temperature of the heater 102 (i.e., the temperature of the heating element) is different from the temperature of the surface of the heater 102 and the temperature of the load placed on the heater 102. In one embodiment, the heater learning module 204 generates heater-load temperature correlation data. The heater-load temperature correlation data provides the temperature of the heater 102 (i.e., the heater temperature) and the time required for the load to reach a setpoint temperature based on the heater temperature and the power applied to the heater 102. For example, if the heater temperature is 500°C and the load temperature is 470°C, i.e., an offset of 30°C, the heater-load temperature correlation data is used to determine the appropriate heater temperature to raise the load temperature to, for example, 490°C within the desired period of time.

[0053] To generate the heater load-temperature correlation data, the heater learning module 204 is configured to execute a heater learning routine during which a load or artifact is placed on the heater 102 for heating. The learning module 204 operates the heater 102 according to a preset operating sequence in which the power control module 206 gradually increases power to the heater 102 to increase the heater temperature. The heater learning module 204 obtains the average temperature and the reference temperature for each heating element from the performance feedback module 202.

[0054] Using the heating element temperature, the learn module 204 obtains the overall heater temperature and correlates the applied power, the duration of the heating operation, and the heater temperature. Additionally, the heater learn module 204 correlates the applied power, the routine time, and the measured reference temperature. Using the two correlation data, the heater learn module 204 correlates the primary temperature (i.e., heater temperature) with each reference temperature over changes in power and time to form heater load correlation data. In one form, the heater learn routine is executed at any time, even when building and updating correlation data.

[0055] The heater learning module 204 may be configured in other suitable ways. For example, instead of measuring the load temperature, the module 204 may use the reference sensor 130 to measure the surface of the heater 102 and correlate the heater and surface temperatures. A predetermined algorithm may be used to estimate the temperature of the load based on the surface temperature to obtain heater-load correlation data.

[0056] In one form, the heater-load correlation data is used by one or more state model controls, including but not limited to rate and manual controls, to perform boost compensation that increases the rate at which the load temperature increases. Specifically, the controller 106 uses the correlation data to know how long it takes for the heater 102 to reach a particular temperature, determine what the heater temperature should be, and how long it will take for the load temperature to reach the desired temperature. Thus, the controller 106 can increase the rate at which the load temperature increases.

[0057] In addition to, or instead of, the heater-load correlation data, the heater learn module 204 is configured to perform an automatic learning resistance-temperature curve control to autonomously generate a resistance-temperature mapping table for a two-wire system. One example of determining a resistance to temperature curve is described in the two-wire system disclosed in U.S. Patent No. 7,196,295. Generally, the resistance of a wire is determined based on the base resistance at a reference temperature, the TCR of the particular material used in the two-wire, and the temperature. The two-wire system can determine the resistance based on the voltage and / or current, and then use the resistance, base resistance, and TCR to determine the temperature. The resistance-temperature curve can be adjusted based on additional resistance from leads or offsets between the reference temperature and the two-wire system, for example.

[0058] The power control module 206 is configured to operate each power converter based on a power output command for each converter 116. In one form, the power output command may be provided by at least one of the heater learning module 204, the state selection module 210, and the system protection module 212. In one form, the power control module 206 outputs a control signal to the driver circuit 120, which in turn operates the control switch 124 of the respective power converter 116 to adjust the input voltage to the desired output voltage of the designated heating element.

[0059] The state model control module 208 and the state selection module 210 are configured to build state model controls and select a desired state model to operate the heater 102. In one form, the state model control module 208 is configured to store one or more state models in the state model control repository 214 and modify or build new state models based on input from a user. For example, Table 1 below provides examples of different state models, which are computer-executable programs for controlling the heater 102 within set conditions. Although specific examples are provided, other state models may be used while remaining within the scope of the present disclosure. [Table 1]

[0060] In one form, a state model control is defined by one or more operational settings for controlling the heater 102 for each state model control. For example, Table 2 shows various settings that may be used to define a state model control. While specific examples are provided, other settings may be used while remaining within the scope of this disclosure. [Table 2]

[0061] Different settings can be used to define different state models, and even different variations of the same type of state model. For example, Figure 4 shows a state model control program 250 defined by six different state models. The six different state models include a power-up control 252, a soft-start control 254, a rate control 256, and three PID controls 258, 260, and 262 (e.g., steady-state controls). Figure 4 illustrates the transition of the control program 250 from one state model to another.

[0062] Each state model is defined by one or more settings that are fixed or adjustable by the user via computing device 135. For example, Figures 5A-5E show the settings for state models 1-5 of state model control program 250 of Figure 4. The type and / or number of user-adjustable settings can be customized based on the use of thermal system 100, and therefore any number, adjustable or fixed, is within the scope of this disclosure.

[0063] FIG. 5A shows the settings of the power-up control 252, which include the power set point to perform a power-up at 2% / min; and the electrical characteristics of the heating element (H EC ) is a user-predefined or adjustable power-up threshold (THPWR―UP ), a transition condition is included to move to State Model 2 (soft start control 254). FIG. 5B shows the settings for the soft start control 254, which include a 0.5% power / minute rate setting with an initial power of 0% and a maximum power of 5%; and a voltage output (V O / P ) is greater than 5%, state model 254 includes a transition condition to exit control 254 and transition to state model 3 (rate control 256). FIG. 5C shows the settings for rate control 256, including: a rate setpoint of 12°C / min; a proportional band (PB) of 200°C, an integral gain (Ti) of 30 seconds, and a derivative gain of 0 seconds (Td); a selectable, but not currently configured, start action; and a transition condition to transition to state model 4 (PID-1 258) when the system is near the power setpoint (SP) with a relative parameter (Rel.Param 1) of 1°C. FIGS. 5D and 5E show the settings for state model controls 4 and 5 (i.e., PID-1 258 and PID-2 260), respectively, both of which are PID controls with different settings assigned. Along with other settings, state model control 4 includes the following two exit conditions: a first state transition to state model 3 (e.g., Rate 256) when the temperature setpoint increases by a relative parameter (Rel.Param 1) of 10°C; and a second state transition to state model 5 (PID-2 260) when the setpoint decreases by a relative parameter (Rel.Param 2) of 10°C. Similarly, state model control 5 also includes two exit conditions: a first exit state transition to state model 6 (PID-3 262) when the system is far from the setpoint (e.g., + / - 5°C), and a second exit state transition to state model 4 (PID-1 258) after a predetermined time has elapsed.

[0064] 5A-5C show example settings for different state models of a particular control program. It should be readily understood that other settings for different state models can be used. Additionally, a state control program may be defined by more than one state model and should not be limited to the examples provided herein. Additionally, the controller 106 may be configured to include multiple state control programs for controlling the operation of the heater 102. Thus, Different state model control programs can be created to accommodate different types of loads, heaters, and performance criteria.

[0065] In one form, via computing device 136, a user selects a control action from stored state control models and state control programs as a selected heater operating state. State selection module 210 is configured to execute the selected heater operating state stored in repository 214 based on information from performance feedback module 202 and settings defined in the state model provided in the selected heater state action. During operation, state selection module 210 determines a desired power level for each heating zone 114 to satisfy the conditions of the executed state model and outputs the power levels to power control module 206. Using feedback information from sensors 130 and 132, state selection module 210 can adjust power to heater 102.

[0066] Thus, the state model control module 208 and state selection module 210 allow a user to dynamically change the control scheme of a given state model control to develop a control program (e.g., fingerprint) for a specific heater. For example, when transitioning from one state to another, the static power level, integral, can be set by the user to a setpoint or conditioned on a variable such as temperature. Thus, the state-based model control can be tailored for each heater, rather than a fixed control scheme for all heaters.

[0067] The system protection module 212 is configured to monitor the thermal system 100 for abnormal operation that could damage the heaters 102 and / or the control system 104. In one form, the system protection module 212 implements at least one of the following protection protocols: inter-zone monitoring; zone-based monitoring; rate-of-change gauges; and / or energy limit control.

[0068] Inter-zone monitoring and zone-based monitoring are examples of coherence control to assess whether the thermal system 100 is maintaining a desired balance along the heaters 102 and minimize or prevent damage, such as ceramic fracture, to the heaters 102. For example, in the case of inter-zone monitoring, the protection module 212 determines the temperature of the heating zones 114 based on information from the performance feedback module 202 and determines whether the difference in temperature between adjacent zones exceeds a temperature fluctuation threshold (e.g., a difference of 10°C). If so, the protection module 212 implements protective measures to minimize or prevent damage to the thermal system 100.

[0069] Zone-based monitors compare the average temperature of the heaters 102 to a reference temperature to determine whether the temperature between the two exceeds a temperature fluctuation threshold. The temperature fluctuation threshold may be the same as or different from that used for the inter-zone monitors. Thus, coherence control can prevent the thermal system 100 from exceeding the fluctuation threshold by, for example, adjusting power to the heaters 102 or shutting down the system.

[0070] Another indicator that the thermal system 100 may be operating abnormally is the rate at which the heater 102 heats up based on the applied power. Specifically, in one form, the rate at which the heater 102 changes its heater temperature and / or electrical response based on the applied power is compared to associated rate range thresholds to determine whether the heater 102 is responding within specifications. For example, if the heater temperature does not increase with an increase in applied power, or if the heater temperature increases rapidly with the same or a small increase in applied power, the protection module 212 flags such behavior as abnormal and implements protective measures. Similarly, an energy limit control sets limits on the amount of power that can be applied to the heater 102, and the protection module 212 outputs protective measures if the thermal system 100 exceeds and / or approaches those limits. For example, the energy limit control is used to set the maximum current at low resistance start-up and the maximum power delivered. The maximum values ​​can be user-configurable or predetermined, for example, based on the specifications of the heater 102, and can vary over a temperature range.

[0071] Protective measures taken by the system protection module 212 include, but are not limited to, instructing the power control module 206 to reduce power to one or more heating zones 114 to control the fluctuations, cutting off power to the heater 102, outputting a message to the computing device 136 regarding the severe temperature fluctuations, and / or turning off the power supplied to the power conversion system 108 by operating the interlock 129.

[0072] The controller 106 may be configured in various suitable ways to perform the operations of the interface module 200, the performance feedback module 202, the heater learning module 204, the power control module 206, the state model control module 208, the state selection module 210, and the system protection module 212. For example, in one form, the controller 106 operates in a learn mode to generate heater load correlation data and / or a resistance-temperature mapping table. The controller 106 also operates in an operate mode to modify the state control model and / or implement selected heater operating states. In one form, the controller 106 monitors the system 100 for abnormal operation when power is applied to the heater 102.

[0073] 6, to select such a mode, the controller 106, via the computing device 136, is configured to display, for example, a main menu GUI 270. In this example, various control options are provided as buttons (e.g., learn mode buttons 272A and 272B and operational mode buttons 274A and 274B). Activation of the desired button causes the controller 106 to execute one or more programs to perform the particular task selected, including generating additional GUIs to request the selected additional information task.

[0074] In addition to operating the controller 106 in a learn mode or an operational mode, the controller 106 is operable to display information regarding heater performance. For example, heater performance may include, but is not limited to, a temperature profile along the surface of the heater 102 to show the temperatures of various zones (e.g., button 276A); a power output graph (e.g., button 276B) providing the amount of power, current, and / or voltage applied to the heater 102; and a heater-load temperature chart (i.e., button 276C) to show heater and load temperatures over time during heating operations. It should be readily understood that the controller 106 may be configured to output other heater performance information. While FIG. 6 shows a specific example of a main menu GUI, other GUIs may be used within the scope of the present disclosure.

[0075] The control system 104 can be implemented in a variety of structural configurations. For example, in one form, FIG. 7 shows a control system interface 300 that includes a case 302 for housing the controller, interlock, power conversion system, and sensor circuitry. The interface 300 also includes one or more communication ports 304 for connecting to one or more external devices, such as a computing device. Depending on the type of reference sensor 130 used, the interface 300 may also include an auxiliary port (not shown) for receiving input from the reference sensor 130 and a power port (not shown) for connecting to the heating element of the heater 102.

[0076] 8 and 9, in one form, the control system of the present disclosure includes an isolation barrier between the power source and the power converter to protect the control system from high AC power from the power source. More specifically, the control system 350 includes an isolation circuit 352 disposed between the power source 118 and the power converter 116 of the power conversion system 108. Although not shown, the control system 350 is configured to include other components of the control system 104, such as a heater controller, an interlock, a heater sensor circuit, etc.

[0077] Among other components, isolation circuit 352 includes an RMS (root mean square) control circuit 354 that controls the bridge duty cycle to control the output RMS, and a direct current (DC) transformer 356. Isolation circuit 352 electrically isolates the power converter from the input line power. The output is floating from earth / ground and L1 / L2 / L3.

[0078] The description of the present disclosure is merely exemplary in nature and, thus, variations that do not depart from the essence of the disclosure are intended to be within the scope of the disclosure. Such variations should not be regarded as a departure from the spirit and scope of the disclosure.

[0079] As used herein, the phrase at least one of A, B, and C should be interpreted to mean a logical non-exclusive OR (A OR B OR C), and not to mean "at least one of A, at least one of B, and at least one of C."

Claims

1. 1. A control system for controlling a heater including at least one heating element, the control system comprising: a power converter operable to provide an adjustable voltage output to the heater, the power converter configured to convert a voltage input from a power source to a voltage output that is equal to or less than the voltage input; a sensor circuit configured to measure an electrical characteristic of a heating element of the heater, the electrical characteristic including at least one of current and voltage; a reference temperature sensor for measuring a reference temperature of the heater; and a controller configured to operate the power converter to control the voltage output to the heater; Equipped with the controller calculates a primary temperature of the heating element based on the electrical characteristic; and determines the voltage output applied to the heater based on at least one of the reference temperature and the primary temperature; The controller is configured to operate in at least one of an operating mode and a learning mode and to execute one or more protection protocols when the heater is supplied with the voltage output.

2. 10. The control system of claim 1, wherein the controller is configured to reduce or cut off power to the heater in response to a difference between the reference temperature and the primary temperature being greater than a preset threshold.

3. The control system of claim 1 , wherein the reference temperature sensor is one of an infrared camera, a thermocouple, and a resistance temperature detector.

4. 2. The control system of claim 1, wherein in the learn mode, the controller is configured to operate the heater to generate heater-load correlation data relating a temperature of the heating element to a temperature of a load disposed on the heater.

5. 5. The control system of claim 4, wherein in the learn mode, the controller is configured to gradually increase power to the heater to increase heat generated by the heater, determine a plurality of primary temperatures, and correlate the primary temperatures with respective reference temperatures detected by the reference temperature sensor to generate heater load correlation data.

6. The control system of claim 5 , wherein the controller is configured to map changes in the primary temperature and the reference temperature over a period of time during which the power is increased.

7. The control system of claim 1 , wherein the reference temperature sensor is configured to measure a temperature of at least one of a load disposed on the heater and a surface of the heater.

8. 2. The control system of claim 1, wherein in said operating mode, said controller performs boost compensation to increase the rate at which said heating element generates heat to heat said reference to a predetermined setpoint temperature.

9. 2. The control system of claim 1, wherein the controller is configured to determine a primary temperature of each heating element based on the electrical characteristics, and, for adjacent zones, adjust the power supplied to one or more heating elements in the adjacent zone based on the primary temperature to control temperature fluctuations across the heater.

10. 10. The control system of claim 9, wherein the controller is configured to reduce power to one zone in response to the one zone having a higher temperature than a temperature of an adjacent zone.

11. 2. The control system of claim 1, wherein in the operational mode, the controller is configured to select one state model control from among a plurality of predetermined state model controls as the operating state of the heater based on at least one of the reference temperature and the primary temperature.

12. The control system of claim 11 , wherein the plurality of predetermined state model controls includes at least one of a power-up control, a soft-start control, a set rate control, and a steady-state control.

13. The control system of claim 11 , wherein each of the state model controls defines one or more operational settings for controlling the heater for the respective state model control.

14. The control system of claim 13 , wherein the one or more operational settings include a transition condition that defines a condition for exiting the operational state and transitioning to another state model control.

15. A heater and A control system according to claim 1; A thermal system comprising:

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