Patent Description:
The present disclosure relates to a method for controlling the thermal performance of an electric heater.

A thermal system for an industrial process typically includes a heater system and a control system to monitor and control the operations of the heater system. The control system may be a temperature proportional-integral-derivative (PID) control system configured to control a temperature of the heater system to a target temperature. However, temperature PID controllers react to thermal system changes once a temperature sensor detects a change in measured temperature. As such, it may be difficult for the temperature PID controller to quickly and timely react to thermal system changes, such as a thermal load change.

<CIT> (<NUM>-<NUM>-<NUM>) describes a hot water heater includes a tank for storing water, one or more heating elements for selectively applying heat to the waler in the tank, and a controller for controlling the healing elements, operative to automatically self-program control of the hot water heater to reduce energy consumption of the hot waler healer based on usage data.

The present disclosure provides a method for controlling a heated process of a heater. The method includes obtaining a setpoint variable indicating a target temperature of the heater. The method includes identifying an energy profile for the heater based on the setpoint variable, where the energy profile provides a defined magnitude of initial electrical energy to be applied to the heater to have a temperature of the heated process reach the target temperature. The method includes obtaining a process variable indicating a performance characteristic of the heated process. The method includes providing electrical energy to the heater based on at least one of the energy profile and the process variable.

In some forms, providing the electrical energy to the heater further includes providing the defined magnitude of initial electrical energy to the heater. In some forms, providing the electrical energy to the heater further includes reducing the electrical energy to the heater in response to the process variable indicating that the temperature of the heater is within a temperature approach band of the target temperature of the heater, where the performance characteristic includes the temperature of the heater. In some forms, the electrical energy is reduced to a steady state electrical power based on a natural time constant. In some forms, the electrical energy is reduced to a steady state electrical power based on a proportional-integral control.

In some forms, the method further includes determining whether the temperature of the heater is less than the setpoint variable. In response to the temperature of the heater being less than the setpoint variable, the electrical energy provided to the heater is based on the identified energy profile and is equal to the defined magnitude of initial electrical energy. In response to the temperature of the heater being greater than the setpoint variable, the method further includes turning-off electrical energy to the heater, and obtaining the process variable indicating the performance characteristic of the heater, where the performance characteristic includes the temperature of the heater. In some forms, in response to the temperature of the heater being greater than the setpoint variable, the method further includes increasing the electrical energy to the heater to a steady state electrical power in response to the temperature of the heater approaching the setpoint variable. In some forms, the electrical energy is increased from zero to the steady state electrical power based on a natural time constant. In some forms, the electrical energy is increased from zero to the steady state electrical power based on a proportional-integral control.

In some forms, the method further includes determining whether the temperature of the heater is equal to the setpoint variable. In some forms, the method further includes controlling the electrical energy to the heater based on a temperature control model for maintaining the temperature of the heater at the setpoint variable. In some forms, the performance characteristic includes at least one of a voltage of the heater, a current of the heater, and a temperature of the heater.

The present disclosure provides a system for controlling a heater. The system includes a processor configured to execute instructions stored in a nontransitory computer-readable medium. The instructions include obtaining a target temperature of the heater and a temperature of the heater, controlling the heater in one of an energy-based control mode and a temperature control mode based on the target temperature and the temperature, and identifying, during the energy-based control mode, an energy profile for the heater based on the target temperature, where the energy profile provides a defined magnitude of initial electrical energy to be applied to the heater to have the temperature reach the target temperature. The method includes providing, during the energy-based control mode, electrical energy to the heater based on the energy profile, and selectively providing, during the temperature control mode, the electrical energy to the heater based on the temperature.

In one form, the instructions for providing, during the energy-based control mode, the electrical energy to the heater based on the energy profile further include providing the defined magnitude of initial electrical energy to the heater, determining whether the temperature of the heater is within a temperature approach band of the target temperature of the heater, reducing the electrical energy provided to the heater to a steady state electrical power in response to the temperature of the heater being within the temperature approach band of the target temperature of the heater. In one form, the instructions for selectively providing, during the temperature control mode, the electrical energy to the heater based on the temperature further include turning off electrical energy to the heater, determining whether the temperature of the heater is within a temperature approach band of the target temperature of the heater, and increasing the electrical energy provided to the heater to a steady state electrical power in response to the temperature of the heater being within the temperature approach band of the target temperature of the heater.

In one form, the instructions further include determining whether the temperature of the heater is equal to the target temperature and controlling the electrical energy provided to the heater based on a temperature control model for maintaining the temperature of the heater in response to the temperature of the heater being equal to the target temperature.

The present disclosure provides a method for learning an energy profile of a heater. The method includes obtaining a setpoint variable indicating a target temperature of the heater and providing electrical energy to the heater, where the electrical energy has a calibration magnitude. The method includes obtaining a process variable indicating a temperature of the heater. When the process variable indicates that the temperature of the heater is equal to the target temperature, the method includes determining a response time of the heater, selectively adjusting gain values based on the response time, and generating an energy profile based on the gain values of the controller and the setpoint variable, where the energy profile correlates the setpoint variable to a predetermined value of electrical energy.

In one form, the energy profile further defines a steady state electrical power that is applied to the heater in response to the temperature of the heater being within a temperature approach band of the target temperature. In one form, the method further includes defining the temperature approach band of the target temperature based on a mathematical model. In one form, the energy profile further defines a duration of time to provide the predetermined value of electrical energy to the heater to have the temperature of the heater reach the target temperature. In one form, selectively adjusting the gain values based on the response time further comprises adjusting the gain values based on a Ziegler-Nichols tuning routine in response to the response time being less than a threshold response time. In one form, the energy profile is further based on the calibration magnitude. In one form, the method further includes selectively adjusting the calibration magnitude when the process variable indicates that the temperature of the heater is equal to the target temperature.

Referring to <FIG>, a thermal system <NUM> including a heater system <NUM> having a heater <NUM> and a control system <NUM> configured to provide a desired thermal response is shown. In one form, the control system <NUM> is configured to control the operation of the heater system <NUM> and, more particularly, the heater <NUM>.

The thermal system <NUM> can be part of various types of industrial processes for controlling a thermal characteristic of a load being heated. For example, the thermal system <NUM> can be part of a semiconductor process in which the heater system <NUM> includes a pedestal heater for heating a wafer (e.g., a load). In this example, the control system <NUM> may be configured to control an energy profile of the pedestal heater, which can vary based on different controls. For example, the controls can include, but are not limited to: power provided to the pedestal heater, an operational mode of the thermal system <NUM> (e.g., a manual mode to control power to the heater <NUM> based on inputs from a user, a cold-start mode to gradually increase temperature of the pedestal heater, a steady-state mode to maintain the pedestal heater at a target temperature, among other defined operation modes for controlling the heater system <NUM>), and/or operational state of different zones of the pedestal heater when the pedestal heater is a multi-zone heater, among other parameters controllable by the thermal system <NUM>. Furthermore, the controls can include, but are not limited to: the type of wafer being heated, gases being injected into a process chamber having the pedestal heater, and/or a pressure differential within the chamber for securing the wafer to the pedestal heater, among other factors.

In another example, the thermal system <NUM> can be used in abatement system of the semiconductor process to heat fluid flowing through a network of conduits. In one form, the heater system <NUM> can include multiple flexible heaters that wrap about the conduits to heat the fluid therein. In yet another example, the thermal system <NUM> can employ cartridge heaters as part of the heater system <NUM> to directly heat fluid (e.g., gas and/or liquid) flowing through conduits or provided within a container.

While specific applications of the thermal system <NUM> are provided herein, the present disclosure may be applicable to other industrial processes having a thermal system to heat a load. Furthermore, the heater <NUM> of the heater system <NUM> should not be limited to the examples provided herein, and the heater <NUM> may include a layered heater, a cartridge heater, a tubular heater, a polymer heater, a flexible heater, among other heaters having a resistive heating element.

The heater system <NUM> can include one or more sensors <NUM> for measuring performance characteristics (i.e., a process variable) of the heater <NUM>, such as, but not limited to: a temperature, a voltage, a current, an electrical power, and/or a resistance of the heater <NUM>, among others. Accordingly, the one or more sensors <NUM> may include a thermocouple, a resistance temperature detector, an infrared camera, a current sensor, and/or a voltage sensor, among others.

In one variation, the heater <NUM> may generate the performance characteristic in lieu of or in addition to the one or more sensors <NUM> generating the performance characteristics. As an example, the heater system <NUM> can be a two-wire heater system, where the heater <NUM> is operable to generate heat and operate as a sensor to measure a performance characteristic of the heater <NUM>. More particularly, the heater <NUM> can include one or more resistive heating elements that operate as a sensor for measuring an average temperature of the resistive heating element based on a resistance of the resistive heating element. An example two-wire heater system is disclosed in <CIT>. In a two-wire system, the thermal system is an adaptive thermal system that merges heater designs with controls that incorporate power, resistance, voltage, and current in a customizable feedback control system that limits one or more these parameters (i.e., power, resistance, voltage, and current) while controlling another. In one form, the control system <NUM> is configured to monitor at least one of current, voltage, and power delivered to the resistive heating element to determine resistance, and thus, temperature of the resistive heating element.

In another variation, as a two-wire heater, the heater <NUM> is configured to include temperature sensing power pins for measuring a temperature of the heater <NUM>. Using the power pins as a thermocouple to measure a temperature of a resistive heating element is disclosed in <CIT>, which is commonly owned with the present application. Generally, the resistive heating element of the heater <NUM> and the control system <NUM> are connected via a first power pin and a second power pin that define a first junction and a second junction, respectively. The first and second power pins function as thermocouple sensing pins for measuring temperature of the resistive heating element of the heater <NUM>. The control system <NUM>, which is in communication with the first and second power pins, may be configured to measure changes in voltage at the first and second junctions. More specifically, the control system <NUM> may measure millivolt (mV) changes at the junctions and then uses these changes in voltage to calculate a temperature of the resistive heating element.

The control system <NUM> is configured to control the heater system <NUM> based on an energy profile that defines an output control for controlling the heater system <NUM>. The output control can be provided in various suitable forms, such as a percent of input power (e.g., <NUM>% input power) and/or an actual voltage level, among others. Furthermore, the control system <NUM> is configured to define one or more energy profiles that are utilized to control the heater system <NUM>.

In one form, the control system <NUM> includes a heater control process database <NUM>, a mode control module <NUM>, an operation control module <NUM>, a learning module <NUM>, an energy profile database <NUM>, and a power module <NUM>. In order to perform the functionality described herein, the control system <NUM> may be implemented by a microcontroller that includes one or more processor circuits configured to execute machine-readable instructions stored in one or more nontransitory computer-readable mediums, such as a random-access memory (RAM) circuit and/or a read-only memory (ROM) circuit. While the heater control process database <NUM>, the mode control module <NUM>, the operation control module <NUM>, the learning module <NUM>, the energy profile database <NUM>, and the power module <NUM> are shown as part of the control system <NUM>, it should be understood that any one of these components may be located on separate controller(s) communicably coupled to the control system <NUM>.

In some forms, the control system <NUM> includes one or more defined control processes stored in the heater control process database <NUM> that, when executed by the control system <NUM>, controls the thermal performance of the heater <NUM>. A given control process may define one or more target temperatures for the heater <NUM>, a process timeline indicating the time and duration of the target temperature(s), and/or a control mode for the control system <NUM>, among other parameters. In one form, a user may select the control process to be performed via an external device, such as a human machine interface (HMI).

In some forms, the mode control module <NUM> is configured to obtain a target temperature and set a control mode of the control system <NUM>. As an example, the mode control module <NUM> is configured to set the energy control mode to an energy profile learning mode provided by the learning module <NUM> and/or an operation control mode provided by the operation control module <NUM>. In one form, the energy control mode is set by the user by way of an external device. For example, the user may have the control system <NUM> operate in the energy profile learning mode to define one or more energy profiles based on one or parameters set by the user and/or defined in a prestored control process. In another form, the energy control mode is automatically set based on the control process to be executed by the control system <NUM>. For example, the control process is configured to identify the control mode, the target temperature(s), and timeline for controlling the heater at the target temperature(s). In another example, the energy control mode is automatically set to the operation control mode once the learning module <NUM> completes an energy profile learning routine, which is described below in further detail with reference to <FIG> and <FIG>.

In some forms, the operation control module <NUM> is configured to perform the control process(es) to determine the output control based on the target temperature and a process variable indicative of a measurable performance characteristic of the heater system <NUM> (e.g., the temperature measurement from the one or more sensors <NUM>). The functionality of the operation control module <NUM> is described below in further detail with reference to <FIG> and <FIG>.

In some forms, the learning module <NUM> is configured to generate and store one or more energy profiles <NUM> in the energy profile database <NUM>. In some forms, the energy profile <NUM> correlates a target temperature to a defined magnitude of initial electrical power and/or energy to be applied to the heater <NUM> to have a temperature of the heater <NUM> reach the target temperature. The energy profile <NUM> may also define a steady state voltage that is applied to the heater <NUM> in response to the temperature of the heater <NUM> being within a defined temperature approach band of the target temperature of the heater <NUM> to provide a transitional control of the heater <NUM> to the target temperature, thereby reducing or inhibiting an overshoot of the target temperature. In some forms, the temperature approach band (e.g., a deviation from the target temperature represented as a temperature threshold tolerance) is unique among each of the energy profiles <NUM>. In one variation, the temperature approach band is equal for each of the energy profiles <NUM>. In some forms, the temperature approach band is defined by a user, a mathematical model, and/or a learning routine, among others. In another form, the temperature approach band of the energy profiles <NUM> may be dynamically updated based on various conditions of the thermal system <NUM>.

In an example application, both the operation control mode and the learning mode may be selected to perform a selected control process. In such application, the operation control module <NUM> operates the heater <NUM> as provided below to control the thermal performance of the heater <NUM>, and the learning module <NUM> is configured to define an energy profile <NUM> for the control process being performed. Accordingly, the defined energy profile <NUM> takes into consideration known and unknown parameters of the industrial process having the thermal system <NUM>. For example, in a semiconductor process, the known and unknown parameters may include mass of the load (e.g., wafer), insertion/removal of fluid/powder, and/or opening/closing of valves/doors.

The power module <NUM> is configured to control the electrical energy provided to the heater system <NUM> based on the output control from one of the operation control module <NUM> and the learning module <NUM>. In one form, the power module <NUM> is electrically coupled to a power source (not shown) and may include a power regulator circuit (not shown) to adjust the power from the power source to a selected power level and apply the adjusted power to the heater <NUM>. Using predefined algorithms and/or a table, the power module <NUM> is configured to select a power level for the heater system <NUM> based on the output control.

Referring to <FIG>, an example block diagram of the operation control module <NUM> is shown. In some forms, the operation control module <NUM> includes a control mode selection module <NUM>, a temperature control loop module <NUM>, and an energy-based control module <NUM>. The control mode selection module <NUM> is configured to set the operation control mode as one of an energy-based control mode or a temperature control mode based on the target temperature and the process variable from the one or more sensors <NUM>. In one form, the control mode selection module <NUM> sets the operation control mode to the energy-based control mode and is thereby controlled by the energy-based control module <NUM> when the target temperature is greater than the measured temperature of the heater <NUM>. On the other hand, when the target temperature is less than or equal to the measured temperature of the heater <NUM>, the control mode selection module <NUM> sets the operation control mode to the temperature control mode and is thereby controlled by the temperature control loop module <NUM>. In one variation, the control mode selection module <NUM> sets the operation control mode to the energy-based control mode when the measured temperature is less than the target temperature by a defined deviation (e.g., a deviation of <NUM>, <NUM>, or other suitable value). Otherwise, the temperature control mode is selected when the measured temperature is greater than the target temperature by the defined deviation.

During the energy-based control mode, the energy-based control module <NUM> is configured to control the heater <NUM> based on the target temperature and a defined energy profile for the target temperature and/or the control process. More particularly, when the temperature of the heater <NUM> is outside of the temperature approach band of the target temperature, the energy-based control module <NUM> is configured to provide a defined magnitude of initial electrical power and/or energy to the heater <NUM> based on the target temperature.

As an example, the energy-based control module <NUM> identifies an energy profile <NUM> from among the energy profiles <NUM> stored in the database <NUM> based on the control process being performed, the target temperature (e.g., target temperature of <NUM>), and/or the measured temperature of the heater. The identified energy profile <NUM> provides a defined magnitude of initial electrical energy and/or power to be applied to the heater <NUM> to have a current temperature of the heater <NUM> reach the target temperature (e.g., the identified energy profile <NUM> indicates that <NUM>,<NUM> Watt-seconds (Ws) of electrical energy needs to be applied to the heater <NUM> to reach a target temperature of <NUM> from the current measured temperature). Subsequently, the energy-based control module <NUM> provides an output control to the power module <NUM> such that the defined magnitude of initial electrical energy and/or power is provided to the heater <NUM>.

The defined magnitude of initial electrical energy and/or power is provided to the heater <NUM> until the temperature of the heater <NUM> is within the temperature approach band. As an example, the energy-based control module <NUM> monitors the temperature of the heater <NUM> to determine if the temperature is within the temperature approach band. Once the temperature of the heater <NUM>, as indicated by the process variable, is within the temperature approach band, the energy-based control module <NUM> provides a steady state magnitude of electrical power associated with the identified energy profile <NUM> to the heater <NUM> (e.g., the identified energy profile <NUM> indicates that the steady state magnitude of electrical power is <NUM>,<NUM> Watts at <NUM>). The steady state magnitude of electrical power may be based on a natural time constant, an overshoot magnitude, a response time, and/or a steady state error of the energy-based control module <NUM>. In some forms, the steady state magnitude of electrical power may be based on a proportional-integral (PI) control routine implemented by the energy-based control module <NUM>.

Once the temperature of the heater <NUM> reaches the target temperature, the operation control module <NUM> transitions to the temperature control mode. During the temperature control mode, the temperature control loop module <NUM> is configured to control the heater <NUM> based on the target temperature and the process variables, such as the temperature of the heater <NUM>. For example, in one form, the temperature control loop module <NUM> performs a PID control that monitors the temperature of the heater <NUM> and determines the difference between the actual temperature and the target temperature. The temperature control loop module <NUM> then determines the level of electrical energy needed for reducing the difference between the actual temperature of the heater <NUM> and the target temperature, as the output control.

By selectively designating the operation control mode between the energy-based control mode (i.e., an open-loop control routine) and the temperature control mode (i.e., a closed loop control routine), the control system <NUM> reduces the response time of the heater <NUM> to reach the target temperature and to transition between varying target temperatures. In addition, in one form, the operation control module <NUM> is configured to select a different operation control mode for different operating conditions. For example, when the temperature of the heater system <NUM> is stable, the operation control module <NUM> selects the temperature control mode to maintain the temperature at the target temperature. During dynamic conditions, the operation control module <NUM> selects the energy-based control to optimize the response while monitoring the temperature of the heater system <NUM>.

With reference to <FIG>, an example block diagram of the learning module <NUM> is shown. In some forms, the learning module <NUM> includes a parameter module <NUM>, a response time module <NUM>, a temperature determination module <NUM>, an energy profile generator module <NUM>, and a parameter adjustment module <NUM>. The learning module <NUM>, which may be implemented by a PID control module, is configured to execute an energy profile learning routine when the mode control module <NUM> sets the control system <NUM> to the energy profile learning mode.

The learning module <NUM> may execute the energy profile learning routine periodically to define the energy profiles <NUM>. In some forms, the learning module <NUM> may execute the energy profile learning routine in conjunction with the operation control routine executed by the operation control module <NUM>, thereby enabling the control system <NUM> to identify various conditions of the thermal system <NUM>, such as energy consumption, heater or sensor failure, changes in heat transfer, among other conditions of the thermal system <NUM>.

In some forms, the learning module <NUM> is configured to generate an energy profile <NUM> for a range of setpoint/target temperatures while executing the energy profile learning routine (e.g., the learning module <NUM> is configured to generate an energy profile <NUM> for a plurality of target temperature between -<NUM> and <NUM>, including endpoints). In some forms, the energy profile <NUM> correlates a target temperature to a defined magnitude of initial electrical energy and/or power to be applied to the heater <NUM> and/or a duration of time to provide the electrical energy to have a temperature of the heater <NUM> reach the target temperature. The energy profile <NUM> may also define a steady state voltage magnitude of the electrical energy that is applied to the heater <NUM> in response to the process variable indicating that the temperature of the heater <NUM> is within a temperature approach band of the target temperature of the heater <NUM>. In some forms, during the energy profile learning routine, the temperature approach band for each energy profile <NUM> is also defined by, for example, a user, a mathematical model, and/or a learning routine, among others.

During the energy profile learning routine, the parameter module <NUM> is configured to obtain a setpoint variable indicating a target temperature of the heater <NUM> (e.g., <NUM>) and provides an output control such that the power module <NUM> outputs electrical energy having a calibration magnitude (e.g., <NUM>,<NUM> Ws) to the heater <NUM>. Furthermore, the parameter module <NUM> is configured to designate a set of gain values for evaluating and controlling the heater <NUM> during the energy profile learning routine (i.e., the parameter module <NUM> defines at least one of proportional gain values, integral gain values, and/or derivative gain values of the learning module <NUM>). The set of gain values may be determined using, for example, the Ziegler-Nichols tuning method.

While the electrical energy is provided to the heater <NUM>, the temperature determination module <NUM> is configured to determine the temperature of the heater <NUM> based on the performance characteristic of the heater <NUM>, as the process variable. Furthermore, while the electrical energy is provided to the heater <NUM>, the response time module <NUM> is activated and is configured to increment a corresponding value proportional to an amount of elapsed time. When the temperature of the heater <NUM> is equal to the target temperature, the response time module <NUM> is configured to determine a response time of the heater <NUM>. As used herein, the "response time of the heater <NUM>" refers to an amount of time needed for the heater <NUM> to reach the target temperature after obtaining the setpoint variable. In some forms, the response time of the heater <NUM> may be based on gain values of the learning module <NUM> (e.g., proportional gain values, integral gain values, and/or derivative gain values).

The energy profile generator module <NUM> is configured to generate the energy profile <NUM> based on the gain values, the target temperature, the calibration magnitude, and the response time of the heater <NUM>. As an example, if the response time of the heater <NUM> is determined to be sufficient for controlling the heater <NUM> (i.e., the response time is less than a threshold value), the energy profile generator module <NUM> generates the energy profile <NUM> for the corresponding target temperature, and the energy profile <NUM> correlates the calibration magnitude and the gain values to the particular target temperature. Furthermore, if the response time of the heater <NUM> is determined to be sufficient for controlling the heater <NUM>, the energy profile generator module <NUM> may also correlate a steady state magnitude to the particular target temperature, where the steady state magnitude is based on a natural time constant as indicated by the gain values.

As another example, if the response time of the heater <NUM> is determined to be insufficient for controlling the heater <NUM> (i.e., the response time is greater than a threshold value), the parameter adjustment module <NUM> may adjust at least one of the calibration magnitude and the gain values to reduce the response time of the heater <NUM>. In some forms, the parameter adjustment module <NUM> may selectively adjust the gain values based on the Ziegler-Nichols tuning method. In some forms, the parameter adjustment module <NUM> may increase the calibration magnitude to reduce the response time of the heater <NUM>. The parameter adjustment module <NUM> may repeatedly adjust at least one of the calibration magnitude and the gain values until the response time of the heater <NUM> is determined to be sufficient for controlling the heater <NUM>.

In one form, the learning module <NUM> of the present disclosure can improve the response of the heater system <NUM> to recurrent dynamic conditions that may not necessarily require user input. For example, the learning module <NUM> may perform machine learning routine to predict the occurrence and severity of dynamic conditions and ascertain the control mode and control setting to improve the control system response. Accordingly, the control system <NUM> can improve and/or maintain performance as components of the thermal system <NUM> gradually change. Furthermore, data collected and determined by the control system <NUM> can be provided to the user for additional analytics.

With reference to <FIG>, a flowchart illustrating an example routine <NUM> for controlling a temperature of the heater system <NUM> during the operation control mode is shown. At <NUM>, the control system <NUM> obtains a setpoint variable indicating a target temperature of the heater <NUM>. In one form, the setpoint variable is provided in a control process to be performed. In another form, the setpoint variable is manually inputted by a user. At <NUM>, the control system <NUM> identifies an energy profile <NUM> for the heater <NUM> based on the setpoint variable. In addition to the setpoint variable, the energy profile <NUM> may be selected based on the control process and the current temperature of the heater <NUM>. At <NUM>, the control system <NUM> obtains a process variable indicating a performance characteristic(s) of the heater <NUM>. At <NUM>, the control system <NUM> provides electrical energy to the heater <NUM> based on at least one of the energy profile <NUM> and the performance characteristic.

With reference to <FIG>, a flowchart illustrating another example routine <NUM> for controlling a temperature of the heater system <NUM> during the operation control mode is shown. At <NUM>, the control system <NUM> determines whether a setpoint variable indicating a target temperature of the heater <NUM> is greater than the temperature of the heater <NUM>. If so, the routine <NUM> proceeds to <NUM>. Otherwise, if the target temperature of the heater <NUM> is less than the temperature of the heater <NUM>, the routine <NUM> proceeds to <NUM>.

At <NUM>, the control system <NUM> provides electrical energy having a defined magnitude of electrical energy and/or power as provided by the energy profile <NUM> for the target temperature. At <NUM>, the control system <NUM> obtains the temperature of the heater <NUM> as the process variable. At <NUM>, the control system <NUM> determines whether the temperature of the heater <NUM> is within the temperature approach band as indicated by the energy profile <NUM>. If so, the routine <NUM> proceeds to <NUM>. Otherwise, if the temperature of the heater <NUM> is not within the temperature approach band, the routine <NUM> proceeds to <NUM>. At <NUM>, the control system <NUM> reduces the magnitude of electrical power to the steady state magnitude of electrical power as indicated by the energy profile <NUM> and then proceeds to <NUM>.

At <NUM> and in response to the setpoint variable indicating the target temperature of the heater <NUM> is less than the temperature of the heater <NUM> at <NUM>, the control system <NUM> discontinues providing electrical energy to the heater <NUM>. At <NUM>, the control system <NUM> obtains the temperature of the heater <NUM> as the process variable. At <NUM>, the control system <NUM> determines whether the temperature of the heater <NUM> is within the temperature approach band as indicated by the energy profile <NUM>. If so, the routine <NUM> proceeds to <NUM>. Otherwise, if the temperature of the heater <NUM> is not within the temperature approach band, the routine <NUM> proceeds to <NUM>. At <NUM>, the control system <NUM> increases the magnitude of electrical power to the steady state magnitude of electrical power as indicated by the energy profile <NUM> (e.g., the magnitude of electrical power is increased from zero to the steady state electrical power based on a proportional-integral control and/or the natural time constant) and then proceeds to <NUM>.

At <NUM>, the control system <NUM> performs a closed-loop temperature control to control the temperature of the heater at the target temperature as provided above. At <NUM>, the control system <NUM> determines whether a new target temperature is available. If so, the routine <NUM> proceeds to <NUM>. Otherwise, the routine <NUM> remains at <NUM> until a new target temperature is available.

With reference to <FIG>, a flowchart of a learning routine <NUM> executed during the energy profile learning mode and by the control system <NUM> is shown. At <NUM>, the control system <NUM> obtains a setpoint variable indicating a target temperature of the heater <NUM>. At <NUM>, the control system <NUM> defines an initial set of gain values and a calibration magnitude for the particular target temperature. At <NUM>, the control system <NUM> provides electrical energy having the calibration magnitude to the heater <NUM>. At <NUM>, the control system <NUM> obtains the temperature of the heater <NUM> as the process variable. At <NUM>, the control system <NUM> determines whether the temperature of the heater <NUM> is equal to the target temperature. If so, the routine <NUM> proceeds to <NUM>. If the temperature of the heater <NUM> is not equal to the target temperature at <NUM>, the routine <NUM> proceeds to <NUM>.

At <NUM>, the control system <NUM> determines a response time of the heater <NUM>. At <NUM>, the control system <NUM> determines whether the response time is less than a threshold response time. If so, the routine <NUM> proceeds to <NUM>, where the control system <NUM> generates an energy profile <NUM> for the particular target temperature based on the gain values and the magnitude of electrical energy. If the response time of the heater <NUM> is greater than the threshold response time at <NUM>, the routine <NUM> proceeds to <NUM>, where the control system <NUM> adjusts at least one of the gain values (e.g., using the Ziegler-Nichols tuning method) and the calibration magnitude and then proceeds to <NUM>.

It should be readily understood that routines <NUM>, <NUM>, and <NUM> are exemplary control routines and that other suitable control routines may be used for performing the operation of the control system of the present disclosure.

Unless otherwise expressly indicated herein, all numerical values indicating mechanical/thermal properties, compositional percentages, dimensions and/or tolerances, or other characteristics are to be understood as modified by the word "about" or "approximately" in describing the scope of the present disclosure. This modification is desired for various reasons including industrial practice, material, manufacturing, and assembly tolerances, and testing capability.

Spatial and functional relationships between elements are described using various terms, including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "above," "below," and "disposed. " Unless explicitly being described as being "direct," when a relationship between first and second elements is described in the present disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, and can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean "at least one of A, at least one of B, and at least one of C.

In this application, the term "module" may be replaced with the term "circuit". The term "module" may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

Claim 1:
A method for controlling a heated process of a heater, the method comprising:
obtaining a setpoint variable indicating a target temperature of the heater;
identifying an energy profile for the heater based on the setpoint variable, wherein the energy profile provides a defined magnitude of initial electrical energy to be applied to the heater to have a temperature of the heated process reach the target temperature;
obtaining a process variable indicating a performance characteristic of the heated process; and
providing electrical energy to the heater based on at least one of the energy profile and the process variable.