Method and system for calibrating controller for determining load resistance

Abstract

A method for enhancing resistance measurement of a load includes: acquiring a plurality of sample resistance values of the load; determining an average resistance value based on the plurality of sample resistance values; determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load; updating an offset correction value of the controller in response to the resistance difference being greater than the resistance tolerance; and measuring the resistance of the load based on the offset correction value and one or more electrical characteristics of the load.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. Patent Application No. 63 / 347,702, filed on June 1, 2022. The disclosure of the above application is hereby incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a controller for calibrating the resistance of a measuring load. Background Art

[0004] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0005] The controller can control one or more performance characteristics of the load based on feedback and / or sensor data associated with the load, such as voltage data, current data, resistance data, temperature data, and other types of feedback / sensor data. As an example, a system can include a heater having one or more resistive heating elements and a controller for controlling power to the heater to generate heat at a temperature set point. As a more specific example, a semiconductor processing system includes a base heater, the base heater including a ceramic substrate and one or more resistive heating elements, the one or more resistive heating elements defining one or more heating zones within the ceramic substrate, and the controller can be configured to independently control the performance characteristics of the one or more heating zones.

[0006] In some applications, the heater may be a "two-wire" heater, in which the resistive heating element serves as both a heater and a temperature sensor, with two wires rather than four wires operably connected to the heating element. A controller configured to control the heater may determine the temperature of the resistive heating element based on the resistance of the resistive heating element. Specifically, the controller calculates the resistance based on voltage and / or current measurements, and determines the temperature of the resistive heating element based on the calculated resistance. Typically, the voltage and current measurements are calibrated to accurately determine the resistance at various temperature set points, and resistance-temperature correlation data is used to determine the temperature based on the calculated resistance. However, within certain power or temperature ranges, it may be difficult to obtain accurate resistance measurements and corresponding temperature measurements due to offset errors or gain errors of the controller.

[0007] The present disclosure addresses these challenges of obtaining accurate temperature measurements. Summary of the invention

[0008] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0009] A method for enhancing resistance measurement of a load includes: obtaining multiple sample resistance values ​​of the load; determining an average resistance value based on the multiple sample resistance values; determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load; updating an offset correction value of a controller in response to the resistance difference being greater than a resistance tolerance; and measuring the resistance of the load based on the offset correction value and one or more electrical characteristics of the load.

[0010] In a variation of the method, it can be implemented individually or in any combination: the offset correction value is a voltage offset correction value, a current offset correction value or a combination thereof; the method includes: obtaining multiple current values ​​of the load, determining an average current value based on the multiple current values, and determining the offset correction value based on the average current value and the resistance difference, wherein the offset correction value is a voltage offset correction value; the offset correction value is also based on the product of the average current value and the resistance difference; the method includes obtaining multiple voltage values ​​and multiple current values ​​of the load, determining an average voltage value based on the multiple voltage values, determining an average current value based on the multiple current values, determining a nominal current value based on the average voltage value and the nominal resistance value, and determining the offset correction value based on the nominal current value and the average current value. value, wherein the offset correction value is a current offset correction value; the nominal current value is also based on the quotient of the average voltage value and the nominal resistance value; the offset correction value is also based on the difference between the nominal current value and the average current value; the method includes providing a calibration signal to the load, wherein a plurality of sample resistance values ​​of the load are obtained in response to providing the calibration signal to the load; the calibration signal has a predetermined voltage value range defined by a first voltage value and a second voltage value, the first voltage value is less than the second voltage value, and the first voltage value and the second voltage value are greater than zero volts; when the calibration signal has the first voltage value, a plurality of sample resistance values ​​of the load are obtained; and in response to a timer value associated with a timer of the controller being greater than a timer threshold, a plurality of sample resistance values ​​of the load are obtained.

[0011] The present disclosure also provides a system for enhancing resistance measurement of a load. The system includes one or more processors and one or more non-transitory computer-readable media, the one or more non-transitory computer-readable media including instructions that can be executed by one or more processors. The instructions include providing a calibration signal to the load, obtaining multiple sample resistance values ​​of the load, determining an average resistance value based on the multiple sample resistance values, determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load, updating an offset correction value of a controller in response to the resistance difference being greater than a resistance tolerance, and measuring the resistance of the load based on the offset correction value and one or more electrical characteristics of the load.

[0012] In a variation of the system, it can be implemented alone or in any combination: the load is a heater including a resistive element; the instructions include obtaining multiple current values ​​of the load, determining an average current value based on the multiple current values, and determining an offset correction value based on the product of the average current value and the resistance difference; the instructions include obtaining multiple voltage values ​​and multiple current values ​​of the load, determining an average voltage value based on the multiple voltage values, and determining an average current value based on the multiple current values, determining a nominal current value based on the quotient of the average voltage value and a nominal resistance value, and determining an offset correction value based on the difference between the nominal current value and the average current value.

[0013] In yet another form, the present disclosure provides a method for enhancing resistance measurement of a load. The method includes providing a calibration signal to the load, wherein the calibration signal has a predetermined voltage value range defined by a first voltage value and a second voltage value, and determining a calibration mode of a controller based on the calibration signal, wherein the calibration mode is one of an offset calibration mode and a gain calibration mode. The method includes, in response to determining that the calibration mode is an offset calibration mode: obtaining multiple sample resistance values ​​of the load, determining an average resistance value based on the multiple sample resistance values, determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load, updating an offset correction value of the controller in response to the resistance difference being greater than a resistance tolerance, and measuring the resistance of the load based on the offset correction value and one or more electrical characteristics of the load.

[0014] In a variation of the method, it can be implemented individually or in any combination: when the calibration signal has a second voltage value, the second voltage value is greater than the first voltage value, and the first voltage value and the second voltage value are greater than zero volts, the calibration mode is a gain calibration mode; when the calibration signal has a first voltage value, the second voltage value is greater than the first voltage value, and the first voltage value and the second voltage value are greater than zero volts, the calibration mode is an offset calibration mode; in response to a timer value associated with a timer of the controller being greater than a threshold timer value, the calibration mode is an offset calibration mode; the offset correction value is a voltage offset correction value, a current offset correction value, or a combination thereof; in response to determining that the calibration mode is an offset calibration mode, obtaining multiple current values ​​of the load, in response to determining that the calibration mode is an offset calibration mode, determining an average current value based on the multiple current values, and in response to determining that the calibration mode is an offset calibration mode , determining an offset correction value based on an average current value and a resistance difference, wherein the offset correction value is a voltage offset correction value; the offset correction value is also based on the product of the average current value and the resistance difference; in response to determining that the calibration mode is an offset calibration mode, obtaining multiple voltage values ​​and multiple current values ​​of the load, in response to determining that the calibration mode is an offset calibration mode, determining an average voltage value based on multiple voltage values ​​and determining an average current value based on multiple current values, in response to determining that the calibration mode is an offset calibration mode, determining a nominal current value based on the average voltage value and a nominal resistance value, and in response to determining that the calibration mode is an offset calibration mode, determining an offset correction value based on the nominal current value and the average current value, wherein the offset correction value is a current offset correction value; the nominal current value is also based on a quotient of the average voltage value and the nominal resistance value; and the offset correction value is also based on a difference between the nominal current value and the average current value.

[0015] In yet another form, the present disclosure provides a system for enhancing resistance measurement of a load. The system includes one or more processors and one or more non-transitory computer-readable media, the one or more non-transitory computer-readable media including instructions executable by the one or more processors. The instructions include providing a calibration signal to the load, wherein the calibration signal has a predetermined voltage value range defined by a first voltage value and a second voltage value, and wherein the second voltage value is greater than the first voltage value, and determining a calibration mode of a controller based on the calibration signal, wherein when the calibration signal has the first voltage value, the calibration mode is an offset calibration mode, and wherein when the calibration signal has the second voltage value, the calibration mode is a gain calibration mode. The instructions include, in response to determining that the calibration mode is an offset calibration mode: obtaining multiple sample resistance values ​​of the load, determining an average resistance value based on the multiple sample resistance values, determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load, updating an offset correction value of the controller in response to the resistance difference being greater than a resistance tolerance, and measuring the resistance of the load based on the offset correction value and one or more electrical characteristics of the load.

[0016] In a variation of the system, it can be implemented individually or in any combination: in response to a timer value associated with a timer of the controller being greater than a threshold timer value, the calibration mode is an offset calibration mode; in response to determining that the calibration mode is the offset calibration mode, multiple current values ​​of the load are obtained, in response to determining that the calibration mode is the offset calibration mode, an average current value is determined based on the multiple current values, and in response to determining that the calibration mode is the offset calibration mode, an offset correction value is determined based on the product of the average current value and the resistance difference; in response to determining that the calibration mode is the offset calibration mode, multiple voltage values ​​and multiple current values ​​of the load are obtained, in response to determining that the calibration mode is the offset calibration mode, an average voltage value is determined based on the multiple voltage values ​​and an average current value is determined based on the multiple current values, in response to determining that the calibration mode is the offset calibration mode, a nominal current value is determined based on the quotient of the average voltage value and the nominal resistance value, and in response to determining that the calibration mode is the offset calibration mode, an offset correction value is determined based on the difference between the nominal current value and the average current value; and the load is a heater including a resistive element.

[0017] 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 DESCRIPTION OF THE DRAWINGS

[0018] In order that the present disclosure may be better understood, various forms thereof given by way of example will now be described with reference to the accompanying drawings, in which:

[0019] Figure 1 is a block diagram of a system according to the teachings of the present disclosure;

[0020] Figure 2 is a graph showing the resistance of a load before and after applying an offset correction value in accordance with the teachings of the present disclosure;

[0021] Figure 3 is a graph showing the temperature of a load before and after applying an offset correction value in accordance with the teachings of the present disclosure;

[0022] Figure 4 is a flow chart of an exemplary calibration mode selection routine according to the teachings of the present disclosure;

[0023] Figure 5 is a flow chart of an example routine for enhancing resistance measurement of a controller in an offset calibration mode in accordance with the teachings of the present disclosure;

[0024] Figure 6 is a flow chart of an example routine for determining a voltage offset correction value in accordance with the teachings of the present disclosure; and

[0025] Figure 7is a flow chart of an example routine for determining a current offset correction value in accordance with the teachings of the present disclosure.

[0026] 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

[0027] The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate the same or corresponding parts and features.

[0028] During operation, a load such as an electric heater may not be supplied with the full range of power (i.e., voltage and / or current) from the power system. As an example, more power is often used during ramp-up or during set point changes than to maintain the electric heater at a desired steady-state temperature. As a result, the electric heater operates primarily at the lower end of the power spectrum throughout its operation.

[0029] However, at the lower end of the power spectrum, the accuracy of the resistance measured by the controller is reduced due to reasons such as thermoelectric voltages (thermoelectric EMFs), radio frequency interference, electromagnetic interference, internal resistance of the power supply of the power system, and analog-to-digital converter circuit (ADC) errors of the controller, which inhibit the accuracy of the resistance measurement. As a specific example, the ADC of the controller may have an offset error that inhibits the accuracy of the resistance measurement, and more specifically, inhibits the accuracy of the resistance-based control and / or operation of the load, such as determining the temperature of the load or performing a corrective action based on resistance / temperature. As used herein, "offset error" refers to the difference between the deviation of the actual voltage (or current) value when the digital output of the ADC increases from 0 to 1 and the expected voltage (or current) deviation when the digital output of the ADC increases from 0 to 1. As an example, if the actual voltage deviation when the digital output of the ADC increases from 0 to 1 is 7.5mV, and if the expected voltage deviation when the digital output of the ADC increases from 0 to 1 is 2.5mV, then the offset correction value is 5.0mV.

[0030] As described in further detail herein, the controller is configured to enhance the resistance measurement by defining one or more offset correction values ​​to accommodate the offset error of the controller during the resistance enhancement routine, thereby improving the accuracy of the resistance measurement obtained at the lower end of the power spectrum. As used herein, "enhancing resistance measurement" refers to improving the accuracy of the resistance measurement obtained by the controller, and "resistance enhancement routine" refers to a routine for improving the accuracy of the resistance measurement obtained by the controller.

[0031] refer to Figure 1, a system 1 is shown, which generally includes a load 10, a power system 20, a controller 30 and one or more electrical characteristic sensors 50. In one form, the load 10 is any device and / or system including a resistive element. In one form, the load 10 is provided by a heater including at least one resistive heating element. As an example, the heater (as the load 10) can be a layered heater, a cartridge heater, a tubular heater, a polymer heater, a flexible heater, and other heater structures having a resistive element. As another example, the load 10 is a "two-wire" heater, in which the resistive heating element is used as a heater and a temperature sensor, and two wires are operably connected to the resistive heating element, instead of four (two for the heater and two for the discrete sensor). For example, such a two-wire capability is disclosed in U.S. Patent No. 7,196,295, which is commonly assigned with the present application, and the entire contents of the patent are incorporated herein by reference. Typically, in a two-wire system, the resistive heating element includes a material that exhibits a changing resistance as the temperature changes, so that the average temperature of the resistive heating element is determined based on the change in the resistance of the resistive heating element. In one form, the resistance of a resistive heating element is calculated by first measuring the voltage across the heating element and the current through the heating element, and then determining the resistance using Ohm's law.

[0032] In one form, the load 10 is a multi-zone pedestal heater including a heating plate and a support shaft disposed at a bottom surface of the heating plate. The heating plate includes a substrate and a plurality of resistive heating elements embedded in or disposed along a surface of the substrate. The resistive heating elements in one form are independently controlled by a controller 30 and define a plurality of heating zones. Exemplary multi-zone heaters are disclosed in applicant's co-pending applications, U.S. Serial No. 63 / 250,655, filed on September 30, 2021, and entitled “METHOD AND SYSTEM FOR CALCULATING ELECTRICAL CHARACTERISTICS OF AN ELECTRIC HEATER,” and U.S. Serial No. 16 / 196,699, filed on November 20, 2018, and entitled “MULTI-ZONE PEDESTAL HEATER HAVING A ROUTING LAYER,” which are commonly owned with the present application and the contents of which are incorporated herein by reference in their entirety.

[0033] In one form, the load 10 is provided by a device having a fixed resistance and a low temperature coefficient of resistance (TCR) (i.e., the load 10 has a TCR that suppresses a nominal resistance shift at a given voltage value). In one form, the load 10 is provided by a sensor including a resistive element having a resistance that varies based on temperature. As an example, the load 10 is a resistance temperature detector (RTD), a thermocouple, or other sensor including a resistive element that depends on temperature (or vice versa). Although examples of loads 10 are provided above, it should be understood that the load 10 can be provided by any device having a resistive element and is not limited to the examples described herein.

[0034] In one form, the power system 20 supplies power to the load 10 based on commands received from the controller 30. In one form, the power system 20 can be electrically coupled to a power source (e.g., a direct current (DC) or alternating current (AC) power source) and include one or more power converter circuits (e.g., a buck converter, an inverter, a rectifier, and other power converter circuits) to output adjustable power to the load 10. In some forms, the power system 20 may also include one or more processors and a memory for storing computer-readable instructions executed by the processor for controlling the duration, amplitude, and electrical characteristics of the power and / or various performance characteristics of the load 10 based on the received commands, which may be the desired power output to be provided to the load 10. In another example, the power converter system of the power system 20 may include a power switch that can be operated by the controller 30 to control the power provided by the power system. It should be readily understood that the power system 20 can be configured in a variety of suitable ways to produce an adjustable power output and should not be limited to the examples provided herein.

[0035] In one form, the one or more electrical characteristic sensors 50 are configured to sense electrical characteristics of the load 10. As an example, the one or more electrical characteristic sensors 50 may include an ammeter, a voltmeter, or a combination thereof (e.g., a power metering chip that measures both current and voltage regardless of the power applied to the load 10) to sense resistance, voltage, and / or current. It should be understood that the one or more electrical characteristic sensors 50 may be provided by any type of sensor configured to sense resistance, voltage, and / or current, and are not limited to the examples described herein.

[0036] In one form, the controller 30 includes a timer module 31, an enhanced start module 32, an output control module 34, a calibration mode module 36, a sampling module 38, an error correction value module 40, a resistance measurement module 46, and a load control module 48. To perform the functions described herein, the controller 30 may include one or more processors configured to execute instructions stored in a non-transitory computer readable medium, such as a random access memory or a read-only memory.

[0037] In one form, the enhancement initiation module 32 selectively initiates the resistance enhancement routine based on a timer value associated with the timer module 31, which is configured to increase the timer value according to the elapsed time. As an example, when the timer value is greater than a threshold timer value (e.g., four minutes), the enhancement initiation module 32 initiates the resistance enhancement routine. In one form, the threshold timer value corresponds to a value where the resistance value of the resistive element 12 is stable or stabilized near an expected resistance value associated with the signal provided to the load via the power system 20.

[0038] In one form, the output control module 34 controls the power system 20 to provide a signal having various electrical characteristics (e.g., voltage, current, power, etc.) to the load 10. For example, the output control module 34 controls the power system 20 to provide a calibration signal to the load 10. In some forms, the calibration signal may have a predetermined voltage value range defined by a first voltage value (e.g., 4V) and a second voltage value (e.g., 104V) greater than the first voltage value. In some forms, each of the first voltage value and the second voltage value is greater than zero volts. As described in further detail below, the error correction value module 40 determines the calibration mode of the controller 30 based on the voltage value of the calibration signal, and selectively updates the offset correction value of the controller 30 based on the determined calibration mode.

[0039] In one form, the calibration mode module 36 determines the calibration mode of the controller 30 based on the voltage value of the calibration signal. As an example, when the calibration signal has a first voltage value (e.g., a lower voltage of two voltage values ​​of a predetermined voltage value range), the calibration mode module 36 determines that the calibration mode is an offset calibration mode. As another example, when the calibration signal has a second voltage value, the calibration mode module 36 determines that the calibration mode is a gain calibration mode.

[0040] When the controller 30 operates in the gain calibration mode, the calibration mode module 36 instructs the gain correction module 42 of the error correction value module 40 to selectively update the gain correction value of the controller 30. Selectively updating the gain correction value of the controller 30 is disclosed in the applicant's co-pending application, application number 63 / 250,655, filed on September 30, 2021, entitled "METHOD AND SYSTEM FOR CALCULATINGELECTRICAL CHARACTERISTICS OF AN ELECTRIC HEATER", which is jointly owned with the present application, and the contents of which are incorporated herein by reference in their entirety. Specifically, the gain correction module 42 reads the voltage count and the current count (i.e., the VI count) and determines the resistance of the load 10 based on the VI count, which is an integer representation of the millivolt (mV) input signal level and is typically a 12, 16 or 24-bit value. In this manner, the gain correction module 42 determines the resistance based on the ratio of the VI counts and adjusts the fixed gain correction value and the dynamic gain correction value of the controller 30 based on the ratio of the VI counts and / or at least one of the voltage counts and the current counts.

[0041] When the controller 30 is operating in the offset calibration mode, the calibration mode module 36 instructs the offset correction module 44 of the error correction value module 40 to selectively update the offset correction value of the controller 30. Additional details regarding the selective updating of the offset correction value are provided below. As used herein, an "offset correction value" refers to a voltage value or current value that offsets or invalidates the offset error of the controller 30 for a given voltage value of the calibration signal.

[0042] In one form, when the calibration signal is provided to the load 10, the sampling module 38 obtains a plurality of sample resistance values, current values ​​(e.g., peak current values ​​or RMS current values), and / or voltage values ​​(e.g., peak voltage values ​​or RMS voltage values) (hereinafter collectively referred to as "values"). In one form, when the calibration signal is provided to the load and has a first voltage value, the sampling module 38 obtains the values. In order to perform the functions described herein, the sampling module 38 may include an ADC configured to convert an analog signal representing a value sensed by one or more electrical characteristic sensors 50 into a digital value for processing and interpretation by the controller 30. As an example, the ADC is a 24-bit device that outputs a digital value representing the sensed electrical characteristic from 0-16,777,215. It should be understood that the ADC may have various bit configurations in other forms and is not limited to the examples described herein.

[0043] In one form, when the controller 30 operates in the offset calibration mode, the offset correction module 44 determines an average resistance value based on a plurality of sample resistance values. In one form, the offset correction module 44 determines an average current value based on a plurality of current values ​​together with the average resistance value. In one form, the offset correction module 44 determines an average voltage value based on a plurality of voltage values ​​and the average resistance value and the average current value.

[0044] In addition, the offset correction module 44 determines the resistance difference based on the average resistance value and the nominal resistance value associated with the load 10. As used herein, the "nominal resistance value associated with the load 10" refers to the expected or predicted resistance value of the load 10 and may be defined, for example, by the manufacturer of the load 10. As a specific example and as shown in equation (1), the sampling module 38 determines the resistance difference based on the nominal resistance value (R nom ) and the average resistance value (R ave ) to determine the resistance difference (R d ):

[0045] R d =R nom -R ave (1)

[0046] In one form, the offset correction module 44 selectively updates the offset correction value of the controller 30 based on the resistance difference and the resistance tolerance. As used herein, "resistance tolerance" refers to a predetermined resistance value in which the offset correction value is updated. In one form, the resistance tolerance is a resistance value corresponding to a given temperature difference indicated by a predetermined resistance-temperature curve of the load 10 (e.g., as a result of the resistance-temperature curve of the load 10 indicating that an increase / decrease of 5 milliohms is associated with an increase / decrease of 0.5C, the resistance tolerance is 5 milliohms). As an example, the offset correction module 44 updates the offset correction value of the controller 30 in response to the resistance difference being greater than the resistance tolerance. As another example, in response to the resistance difference being less than the resistance tolerance (i.e., the controller 30 is calibrated), the offset correction module 44 avoids updating the offset correction value of the controller 30.

[0047] In one form, the offset correction module 44 updates the offset correction value of the controller 30 based on the voltage offset correction value and / or the current offset correction value. As an example, the offset correction module 44 updates the offset correction value of the controller 30 based on the average current value (I ave ) and the resistance difference (R d ) to determine the voltage offset correction value (V offset In one form, the voltage offset correction value (V offset ) corresponds to a voltage offset that corrects the resistance measurement error of the load 10 at the first voltage value of the calibration signal. As an example and as shown in relation (2), the voltage offset correction value (Voffset ) is based on the average current value (I ave ) and the resistance difference (R d ) is the product of:

[0048] V offset =I ave *R d (2)

[0049] In one form, the offset correction module 44 is based on the nominal current value (I nom ) and an average current value (I ave ) to determine the current offset correction value (I offset In one form, the nominal current value (I nom ) is based on and is determined by the sampling module (V ave ) to obtain the average current value and nominal resistance value (R nom As a specific example and as shown in relation (3), the nominal current value is based on the average voltage value (V ave ) and the nominal resistance value (R nom ) of:

[0050]

[0051] In another form, the current offset correction value (I offset ) corresponds to a current offset for correcting the resistance measurement error of the load 10 at the first voltage value of the calibration signal. As shown below with respect to equation (4), the offset correction module 44 is based on the nominal current value (I nom ) and the average current value (I ave ) to determine the di current offset correction value (I offset ):

[0052] I offset =I nom -I ave (4)

[0053] In one form, the resistance measurement module 46 is configured to determine the resistance of the load 10 based on one or more electrical characteristics of the load and an offset correction value (i.e., at least one of a voltage offset correction value and a current offset correction value). As an example, the resistance measurement module 46 obtains a measured voltage value of the load 10 (as one or more electrical characteristics) and adjusts the measured voltage value by the voltage offset correction value. In this way, the accuracy of the resistance measurement obtained by the resistance measurement module 46 is improved for resistance measurements obtained at the lower end of the power spectrum.

[0054] In another form, the load control module 48 controls the operation of the load 10 based on the determined resistance. As an example, the load control module 48 may selectively control the amount of power applied to the load based on the resistance (e.g., ramp-up power, ramp-down power, turn-off power, etc.), determine the temperature of the load 10 based on the resistance, and / or notify an operator of the resistance and / or temperature of the load 10 using, for example, a computing device including a display.

[0055] In the sample application, refer to Figure 2 , a graph 200 illustrating a resistance enhancement routine during an offset calibration mode is shown, and includes graphs 202, 212 representing the measured resistance of two different loads (as indicated by the measured voltage / current of the loads) and graphs 204, 214 representing the nominal resistance of the loads. Prior to the threshold timer value of the timer module 31 (i.e., at times T0 and T10), the load is reset. timer_thresh ), the output control module 34 provides a calibration signal to the load 10, and based on the offset error of the controller 30, the measured resistance (as shown by curves 202 and 212) deviates from the nominal resistance of the load (as shown by curves 204 and 214). When (or after) the threshold timer value has passed (i.e., at the time T when the resistance of the load is stable), the output control module 34 provides a calibration signal to the load 10, and based on the offset error of the controller 30, the measured resistance (as shown by curves 202 and 212) deviates from the nominal resistance of the load (as shown by curves 204 and 214). timer_thresh ), the enhancement initiation module 32 initiates the enhancement routine performed by the sampling module 38 and the error correction value module 40 by determining an offset correction value. Specifically, the error correction value module 40 determines and applies the offset correction value to the measured voltage and / or current to improve the accuracy of the resistance measurement, as indicated by the convergence of the curves 202, 204 and the convergence of the curves 212, 214 after the threshold timer value.

[0056] In another example application, refer to Figure 3 , shows a graph 300 of a resistance enhancement routine during an offset calibration mode, and includes graphs 302, 312 representing measured temperatures of two different loads (as indicated by the measured resistances of the loads) and graphs 304, 314 representing the nominal temperature of the load for a given nominal resistance. Prior to the threshold timer value of the timer module 31 (i.e., at times T0 and T10), the load is reset to zero. timer_thresh ), the output control module 34 provides a calibration signal to the load 10, and based on the offset error of the controller 30, the measured temperature (as shown by curves 302 and 312) deviates from the nominal temperature of the load (as shown by curves 304 and 314). When (or after) the threshold timer value has passed (i.e., at the time T when the resistance of the load is stable), the output control module 34 provides a calibration signal to the load 10, and based on the offset error of the controller 30, the measured temperature (as shown by curves 302 and 312) deviates from the nominal temperature of the load (as shown by curves 304 and 314). timer_thresh), the enhancement startup module 32 initiates the enhancement routine performed by the sampling module 38 and the error correction value module 40 by determining an offset correction value. Specifically, the error correction value module 40 determines and applies the offset correction value to the measured voltage and / or current to improve the accuracy of the resistance / temperature measurement, as indicated by the convergence of the curves 302, 304 and the convergence of the curves 312, 314 after the threshold timer value.

[0057] refer to Figure 4 , a flow chart illustrating a calibration mode selection routine 400 is shown. At 404, the controller 30 determines the output voltage of the calibration signal and the corresponding calibration mode. As an example, when the calibration signal has a first voltage value (e.g., the lower voltage of two voltage values ​​in a predetermined voltage value range), the controller 30 determines that the calibration mode is an offset calibration mode. As another example, when the calibration signal has a second voltage value, the controller 30 determines that the calibration mode is a gain calibration mode. At 408, the controller 30 determines whether the calibration mode is an offset calibration mode. If the calibration mode is an offset calibration mode, the calibration mode selection routine 400 proceeds to 412, where the controller 30 selectively updates at least one of a voltage offset correction value and a current offset correction value. If the calibration mode is not an offset calibration mode (i.e., a gain calibration mode), the calibration mode selection routine 400 proceeds to 416, where the controller 30 selectively updates the gain correction value.

[0058] refer to Figure 5 , a flow chart illustrating a routine 500 for measuring resistance of a controller in an enhanced offset calibration mode is shown. At 504, the controller 30 obtains a sample resistance value of the load 10 when the calibration signal is provided to the load 10. At 508, the controller 30 determines whether the timer value is greater than the timer threshold. If so, the routine 500 proceeds to 512; if the timer value is less than the timer threshold, the routine 500 continues to 504. At 512, the controller 30 determines an average resistance value based on a plurality of sample resistance values, and at 516 determines a resistance difference based on the average resistance and the nominal resistance.

[0059] At 520, the controller 30 determines whether the resistance difference is greater than the resistance tolerance. If so, the routine proceeds to 524, where the controller 30 updates the voltage offset correction value and / or the current offset correction value, and then proceeds to 528. Figure 6 An example routine for determining and updating a voltage offset correction value is described in more detail and is referenced below. Figure 7An example routine for determining and updating a current offset correction value is described in more detail. At 524, if the resistance difference is less than the resistance tolerance, the routine 500 proceeds to 528, where the controller 30 determines that the resistance measurement is calibrated. At 532, the controller 30 measures the resistance of the load 10 based on the offset correction value and one or more electrical characteristics obtained from the one or more electrical characteristic sensors 50.

[0060] refer to Figure 6 , a flow chart illustrating a routine 600 for determining and updating a voltage offset correction value is shown. At 604, the controller 30 obtains a plurality of current values ​​of the load 10, and determines an average current value based on the plurality of current values ​​at 608. At 612, the controller 30 determines a voltage offset correction value based on the product of the average current value and the resistance difference.

[0061] Now refer to the figure Figure 7 , a flow chart illustrating a routine 700 for determining and updating a current offset correction value is shown. At 704, the controller 30 obtains a plurality of current values ​​and voltage values ​​of the load 10, and determines an average current value and an average voltage value at 708. At 712, the controller 30 determines a nominal current value based on a quotient of the average voltage value and a nominal resistance value. At 716, the controller 30 determines a current offset correction value based on a difference between the nominal current value and the average current value.

[0062] Unless otherwise expressly stated, in describing the scope of the present disclosure, all numerical values ​​expressing mechanical / thermal properties, composition percentages, dimensions and / or tolerances or other properties should be understood to be modified by the word "about" or "approximately". Such modifications are required for various reasons including industrial practice, manufacturing techniques and testing capabilities.

[0063] 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."

[0064] In this application, the term "controller" may be replaced by the term "circuit". In this application, the term "controller" and / or "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 functionality; or a combination of some or all of the above, such as in a system on a chip.

[0065] The term "code" may include software, firmware, and / or microcode, and may refer to programs, routines, functions, classes, data structures, and / or objects. The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium as used herein does not encompass transient electrical or electromagnetic signals propagated through a medium (such as on a carrier wave); thus, the term computer-readable medium may be considered tangible and non-transitory.

[0066] The description of the present disclosure is merely exemplary in nature, and therefore, variations that do not depart from the essence of the present disclosure are intended to be within the scope of the present disclosure. These variations should not be regarded as departing from the spirit and scope of the present disclosure.

Claims

1. A method for enhancing resistance measurement of a load, the method comprising: obtaining a plurality of sample resistance values ​​of the load; determining an average resistance value based on the plurality of sample resistance values; determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load; updating an offset correction value of a controller in response to the resistance difference being greater than a resistance tolerance; as well as A resistance of the load is measured based on the offset correction value and one or more electrical characteristics of the load. 2 . The method of claim 1 , wherein the offset correction value is a voltage offset correction value, a current offset correction value, or a combination thereof.

3. The method according to claim 2, further comprising: Acquiring multiple current values ​​of the load; determining an average current value based on the plurality of current values; as well as The offset correction value is determined based on the average current value and the resistance difference, wherein the offset correction value is the voltage offset correction value. 4 . The method of claim 3 , wherein the offset correction value is further based on a product of the average current value and the resistance difference.

5. The method according to claim 2, further comprising: Acquiring multiple voltage values ​​and multiple current values ​​of the load; determining an average voltage value based on the plurality of voltage values, and determining an average current value based on the plurality of current values; determining a nominal current value based on the average voltage value and the nominal resistance value; as well as The offset correction value is determined based on the nominal current value and the average current value, wherein the offset correction value is the current offset correction value. The method of claim 5 , wherein the nominal current value is further based on a quotient of the average voltage value and the nominal resistance value. 7 . The method of claim 5 , wherein the offset correction value is further based on a difference between the nominal current value and the average current value. 8 . The method of claim 1 , further comprising providing a calibration signal to the load, wherein the plurality of sample resistance values ​​of the load are acquired in response to providing the calibration signal to the load.

9. The method according to claim 8, wherein: The calibration signal has a predetermined voltage value range defined by a first voltage value and a second voltage value; The first voltage value is less than the second voltage value; as well as The first voltage value and the second voltage value are greater than zero volts. 10 . The method of claim 9 , wherein the plurality of sample resistance values ​​of the load are acquired when the calibration signal has the first voltage value. 11 . The method of claim 8 , wherein the plurality of sample resistance values ​​of the load are obtained in response to a timer value associated with a timer of the controller being greater than a timer threshold.

12. A system for enhancing resistance measurement of a load, the system comprising: One or more processors and one or more non-transitory computer-readable media comprising instructions executable by the one or more processors, wherein the instructions comprise: providing a calibration signal to the load; acquiring a plurality of sample resistance values ​​of the load in response to providing the calibration signal; determining an average resistance value based on the plurality of sample resistance values; determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load; updating the offset correction value in response to the resistance difference being greater than a resistance tolerance; and A resistance of the load is measured based on the offset correction value and one or more electrical characteristics of the load.

13. The system of claim 12, wherein the load is a heater comprising a resistive element.

14. The system of claim 12, wherein the instructions further comprise: Acquiring multiple current values ​​of the load; determining an average current value based on the plurality of current values; as well as The offset correction value is determined based on a product of the average current value and the resistance difference.

15. The system of claim 12, wherein the instructions further comprise: Acquiring multiple voltage values ​​and multiple current values ​​of the load; determining an average voltage value based on the plurality of voltage values, and determining an average current value based on the plurality of current values; determining a nominal current value based on a quotient of the average voltage value and the nominal resistance value; as well as The offset correction value is determined based on a difference between the nominal current value and the average current value.

16. A method for enhancing resistance measurement of a load, the method comprising: providing a calibration signal to the load, wherein the calibration signal has a predetermined voltage value range defined by a first voltage value and a second voltage value; determining a calibration mode of a controller based on the calibration signal, wherein the calibration mode is one of an offset calibration mode and a gain calibration mode; as well as In response to determining that the calibration mode is the offset calibration mode: obtaining a plurality of sample resistance values ​​of the load; determining an average resistance value based on the plurality of sample resistance values; determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load; updating an offset correction value of the controller in response to the resistance difference being greater than a resistance tolerance; as well as A resistance of the load is measured based on the offset correction value and one or more electrical characteristics of the load.

17. The method of claim 16, wherein: When the calibration signal has the second voltage value, the calibration mode is the gain calibration mode; The second voltage value is greater than the first voltage value; as well as The first voltage value and the second voltage value are greater than zero volts.

18. The method of claim 16, wherein: When the calibration signal has the first voltage value, the calibration mode is the offset calibration mode; The second voltage value is greater than the first voltage value; as well as The first voltage value and the second voltage value are greater than zero volts.

19. The method of claim 16, wherein the calibration mode is the offset calibration mode in response to a timer value associated with a timer of the controller being greater than a threshold timer value.

20. The method of claim 16, wherein the offset correction value is a voltage offset correction value, a current offset correction value, or a combination thereof.

21. The method according to claim 20, further comprising: In response to determining that the calibration mode is the offset calibration mode, acquiring a plurality of current values ​​of the load; In response to determining that the calibration mode is the offset calibration mode, determining an average current value based on the plurality of current values; as well as In response to determining that the calibration mode is the offset calibration mode, the offset correction value is determined based on the average current value and the resistance difference, wherein the offset correction value is the voltage offset correction value.

22. The method of claim 21, wherein the offset correction value is further based on a product of the average current value and the resistance difference.

23. The method of claim 20, further comprising: In response to determining that the calibration mode is the offset calibration mode, acquiring a plurality of voltage values ​​and a plurality of current values ​​of the load; In response to determining that the calibration mode is the offset calibration mode, determining an average voltage value based on the plurality of voltage values ​​and determining an average current value based on the plurality of current values; In response to determining that the calibration mode is the offset calibration mode, determining a nominal current value based on the average voltage value and the nominal resistance value; as well as In response to determining that the calibration mode is the offset calibration mode, the offset correction value is determined based on the nominal current value and the average current value, wherein the offset correction value is the current offset correction value.

24. The method of claim 23, wherein the nominal current value is further based on a quotient of the average voltage value and the nominal resistance value.

25. The method of claim 23, wherein the offset correction value is further based on a difference between the nominal current value and the average current value.

26. A system for enhancing resistance measurement of a load, the system comprising: One or more processors and one or more non-transitory computer-readable media comprising instructions executable by the one or more processors, wherein the instructions comprise: providing a calibration signal to the load, wherein the calibration signal has a predetermined voltage value range defined by a first voltage value and a second voltage value, and wherein the second voltage value is greater than the first voltage value; determining a calibration mode of a controller based on the calibration signal, wherein when the calibration signal has the first voltage value, the calibration mode is an offset calibration mode, and wherein when the calibration signal has the second voltage value, the calibration mode is a gain calibration mode; and In response to determining that the calibration mode is the offset calibration mode: obtaining a plurality of sample resistance values ​​of the load; determining an average resistance value based on the plurality of sample resistance values; determining a resistance difference based on the average resistance value and a nominal resistance value associated with the load; updating the offset correction value in response to the resistance difference being greater than a resistance tolerance; and A resistance of the load is measured based on the offset correction value and one or more electrical characteristics of the load.

27. The system of claim 26, wherein: In response to a timer value associated with a timer of the controller being greater than a threshold timer value, the calibration mode is the offset calibration mode.

28. The system of claim 26, wherein the instructions further comprise: In response to determining that the calibration mode is the offset calibration mode, acquiring a plurality of current values ​​of the load; In response to determining that the calibration mode is the offset calibration mode, determining an average current value based on the plurality of current values; as well as In response to determining that the calibration mode is the offset calibration mode, the offset correction value is determined based on a product of the average current value and the resistance difference.

29. The system of claim 26, wherein the instructions further comprise: In response to determining that the calibration mode is the offset calibration mode, acquiring a plurality of voltage values ​​and a plurality of current values ​​of the load; In response to determining that the calibration mode is the offset calibration mode, determining an average voltage value based on the plurality of voltage values ​​and determining an average current value based on the plurality of current values; In response to determining that the calibration mode is the offset calibration mode, determining a nominal current value based on a quotient of the average voltage value and the nominal resistance value; as well as In response to determining that the calibration mode is the offset calibration mode, the offset correction value is determined based on a difference between the nominal current value and the average current value.

30. The system of claim 26, wherein the load is a heater comprising a resistive element.

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