HK1131851B - Adaptive temperature controller - Google Patents

Description

Self-adaptive temperature controller

Technical Field

The present invention relates to a device for the synchronous control and monitoring of the temperature of a heating element. In particular, the device relates to temperature control of heating elements for chromatographic analysis, including heating of columns, detectors and other components, although the device may be used in any system where precise heating over a range of temperatures is desired.

Background

An adaptive temperature controller for use with any electrically conductive material is disclosed. It is often necessary to maintain a portion of the test equipment or other product above ambient temperature. This is achieved in the prior art by various temperature controllers. It is known to provide a heat source which is easy to control. Most often heat is transferred from the conductive material. In the prior art the temperature of the conductor material is monitored by a separate device, typically a Resistance Temperature Detector (RTD). This, however, requires multiple parts, thereby increasing the space occupied by the apparatus, the weight of the apparatus, and its cost. Furthermore, such systems typically do not produce rapid temperature changes. Moreover, the heating of the device is not constant and is often not rapid enough.

It is therefore desirable to have an improved temperature controller that has fewer components, can reduce weight, space, and cost, can provide constant heating, and can perform rapid heating and cooling.

Disclosure of Invention

The adaptive temperature controller disclosed herein comprises a temperature sensor, a means for measuring resistance, a conductive material, and a power source. In operation, the controller determines the resistance of the conductive material at ambient temperature and is able to determine the corresponding resistance of the conductive material at a temperature within a temperature range and apply the necessary voltage or current to achieve that resistance. The temperature of the conductive material may be determined by using a temperature sensor or by an estimation based on the ambient air temperature. Thus, the voltage or power can be varied instantaneously to provide near infinite control over the temperature of the material.

The foregoing and other objects, features and advantages of the invention will be more readily understood upon consideration of the following description of the invention taken in conjunction with the accompanying drawings.

Drawings

So that the manner in which the above recited features, advantages and objects of the present invention, as well as others which will become apparent, are attained and can be understood in detail, more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the appended drawings illustrate only typical preferred embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

FIG. 1a depicts a cross-sectional view of one embodiment of the prior art.

FIG. 1b depicts a cross-sectional view of another embodiment of the prior art.

Figure 2a depicts direct heating of a component by an adaptive temperature controller.

Figure 2b depicts components controlled by an adaptive temperature controller for direct heating.

Figure 3a depicts indirect heating of a component by an adaptive temperature controller.

Figure 3b depicts components that are controlled by the adaptive temperature controller for indirect heating.

Figure 4 depicts a component 101 where heating is controlled by an adaptive temperature controller through a pulse width modulated switching power supply controlled by a microcontroller/microprocessor.

Fig. 5 depicts a component 101 where heating and cooling are controlled by an adaptive temperature controller.

Fig. 6 depicts a component 101 in which heating is controlled by an adaptive temperature controller comprising a computer interface.

FIG. 7 depicts a flow diagram of an embodiment having steps for calibrating an adaptive temperature controller against a conductive material.

FIG. 8 depicts a flow diagram of another embodiment of the steps of calibrating an adaptive temperature controller against a conductive material.

Detailed Description

As shown in fig. 1a and 1b, in known temperature controllers, the conductor element 250 and the sensor 251 are located in close proximity to the component 301 of the system 300 or around the component 301 to monitor the heating of the element 301 and the temperature of the element 301, respectively. It is known to provide a heating source that is easy to control. Heat is most often transferred from the conductive element 250 and subsequently dissipated to the element 301. Conductive element 250 may be placed adjacent (fig. 1a) or around (fig. 1b) element 301. In the prior art, the temperature of the conductive element 250 is monitored by a single temperature sensor 251, typically an RTD. This requires multiple parts, which increases the space occupied by the apparatus, the weight of the apparatus, and its cost.

The electrically conductive material 50 may be used to directly or indirectly heat a component 101 of the system 100, the component 101 being, for example, a detector or column in a chromatographic analysis. In performing chromatography, the component 101 may be a chromatography column 102 of a chromatography system 100, the system 100 comprising an analyte injector 103 and a detector 104. During direct heating, as shown in FIG. 2a, the component 101, a post, of the system 100 is at least partially formed of the electrically conductive material 50, as shown in cross-section in FIG. 2 b. During indirect heating, as shown in FIG. 3a, the conductive material 50 contacts the component 101 of the system 100, as shown in cross-section in FIG. 3 b. In an indirect heating process, the contacted or surrounded component 101 may be a detector, column, or other device. In fig. 3a, the component 101 is still a post. The temperature to which the conductive material 50 heats the element, the heating rate, and the duration of heating at any temperature are controlled by the adaptive temperature controller 10. In alternative embodiments, the adaptive temperature controller may be used in conjunction with any system in which it is desirable to precisely control the temperature over a range.

As shown in fig. 2a and 3a, in operation, the electrically conductive material 50 used with the adaptive temperature controller 10 has a known electrical resistance as a function of temperature. Adaptive temperature controller 10 is in conductive communication with conductive material 50. For the electrically conductive material 50, the relationship between its resistance and temperature can be obtained by the adaptive temperature controller 10 by applying a formula or by interpolation of such a data table. Since the electrical resistance of the conductive material 50 is known as a function of temperature, the temperature of the conductive material 50 can be determined by dynamically measuring the electrical resistance of the conductive material 50. As described below, the temperature of the conductive material 50 may be determined by communication with the temperature sensor 30 or by estimation based on the ambient air temperature determined by the sensor 30. So that the temperature of the conductive material 50 can be controlled depending on the current (or voltage or both) applied to the conductive material 50. In a preferred embodiment, the conductive material 50 is nickel.

When the resistance of the electrically conductive material 50 is not directly known, but its normalized resistance characteristics are known, such as when the length or diameter of a nickel wire is unknown, the adaptive temperature controller 10 for use with the electrically conductive material 50 can be calibrated by measuring the resistance of the electrically conductive material 50 when the temperature sensor 30 is used to measure the corresponding temperature of the electrically conductive material 50. A scaling factor is derived by dividing the measured resistance of the conductive material 50 by the normalized resistance of the material comprising the conductive material 50 at the reference temperature, and then the scaling factor may be applied to the normalized resistance characteristic to determine the resistance of the conductive material 50 at the particular temperature.

Unlike the prior art, any length or size of conductive material 50 may be used for heating by using the adaptive temperature controller 10. It is of great interest to be able to use any length or size of material, since the dimensions of the heated material will also vary due to the technique of the material's waving and cutting. Furthermore, unlike the prior art, a separate temperature sensor is not required since the temperature can be determined at any time by measuring the applied voltage and current.

It is desirable that the adaptive temperature controller 10 include a learning step to determine the responsiveness of the resistance, and thus the temperature, of the conductive material 50 to changes in current, voltage or power. Determining responsiveness is important to reduce or eliminate temperature overshoot and/or undershoot by the adaptive temperature controller 10. After determining the resistance of the conductive material 50 at ambient temperature, the adaptive temperature controller 10 may then determine the rate of temperature increase relative to the increase in voltage, current, or power. The large diameter conductive material 50 has a lower rate of temperature rise proportional to an increase in current, voltage or power. Similarly, the small diameter conductive material 50 has a higher rate of temperature rise proportional to an increase in current, voltage or power. In each case, the change in temperature is also related to the known thermal resistivity of the material comprising the conductive material 50. The thermal resistance coefficient may be assumed to be a constant for the operating range. Adaptive temperature controller 10 may thus determine the change in resistance caused by a burst of current, voltage, or power applied to conductive material 50. Adaptive temperature controller 10 thus avoids overshoot or undershoot of the expected temperature of the rate of temperature change by determining in advance the responsiveness of conductive material 50 to changes in current, voltage or power. In alternative embodiments, adaptive temperature controller 10 may include a look-up table of known materials for electrically conductive material 50 at various temperatures and include an appropriate thermal resistance coefficient for electrically conductive material 50 at that temperature to determine the associated increase in temperature. In a further embodiment, adaptive temperature controller 10 may record the change in resistance as a function of the change in current throughout operation, thereby plotting the function throughout operation.

Adaptive temperature controller 10 may control or maintain one or more conductive materials 50.

Further, the adaptive temperature controller 10 may control a conductive material 50 to provide different temperatures, such as a step or ramp temperature increase, to a particular device or during a corresponding time period.

In a further embodiment, the adaptive temperature controller 10 may be used in conjunction with a component 101 constructed of a conductive material 50, such as nickel. Once the thermal resistivity of the conductive material 50 is known, the temperature of the component 101 can be controlled such that the temperature can be increased at a step or fixed rate to enhance separation between compounds having similar boiling points.

The adaptive temperature controller 10, which controls the temperature of the conductive material 50 by determining the resistance and applying power, current or voltage, has many advantages over the prior art, particularly temperature controllers using heated tubes. The mass of the adaptive temperature controller 10 is less than the mass of the temperature controller since no separate heating tube is required between the heating element and the temperature controller. Furthermore, since the heat flux is emitted through a large area, rather than being emitted from a specific location in relation to the heating tube, local area temperature increases or decreases can be avoided. Further, the temperature may be more evenly distributed since heat is transferred from the surface along the length of the column 101 to provide a more even distribution along its length rather than from the side associated with the heating tube. Finally, the temperature rise can be accomplished very quickly because heat is generated inside the electrically conductive material 50 rather than being transferred from an external element through the thermally conductive material.

As shown in fig. 4, in one embodiment, the component 101 is constructed of an electrically conductive material 50, and the heat generating power is supplied by an adaptive temperature controller 10 via a pulse width modulated switching power supply 11 controlled by a microcontroller/microprocessor 12, although other power control systems known in the art may be used. The current supplied to the conductive material 50 is obtained by detecting the voltage drop across a current sense resistor 60, wherein the current sense resistor 60 is located between the pulse width modulated switching power supply and the conductive material 50, typically 0.1 ohms. The voltage across the conductive material 50 is likewise detected. An amplifier may be used to appropriately scale the detected voltage before the representative signal is passed to the analog-to-digital converter. The digital signal thus obtained, for example 1000 times per second, is passed to the microcontroller, wherein the relevant resistance value is obtained by ohm's law, i.e. by dividing the converted voltage value by the converted current value. The relative resistance value may be compared to a reference resistance value for temperature control using a conventional proportional-integral-derivative (PID) control algorithm. The temperature of the conductive material 50 may also be determined for display or recording by solving equations for temperature resistance known in the art or calculating differences from a table.

To ramp the temperature up, the detection signal from the current detection circuit may be used to control the rate of temperature change, linear, exponential, or otherwise, depending on the control of the constant current in the conductive material 50.

In a further embodiment shown in fig. 5, adaptive temperature controller 10 may be used to control the temperature of conductive material 50 and fan 70, where fan 70 may cause air flow around component 101. The fan 70 may be used to increase the cooling rate of the conductive material 50.

In a further embodiment shown in figure 6,adaptive temperature controller 10 includes a computer terminal 80. The computer terminal 80 provides a control interface via a keyboard 81 and a monitor 82. The computer terminal 80 may be any computer including a conventional desktop or palmtop computer, such as a Palm computerThe related product of (1), the conductive material 50 calibration may be implemented in the following steps as shown in fig. 7:

1) step 701-identify the material of the conductive material 50;

2) step 702-the adaptive temperature controller 10 obtains the normalized resistance characteristics of the conductive material 50;

3) step 703-stabilizing the temperature of the conductive material 50 at a predetermined temperature, which may be an ambient temperature or an elevated temperature close to the use temperature of the conductive material 50;

4) step 704 — adaptive temperature controller 10 supplies voltage or current to conductive material 50 at least once and measures the current or voltage flowing through;

5) step 705-measuring the temperature of the conductive material 50 by the temperature sensor 30;

6) step 706-the adaptive temperature controller 10 receives the temperature of the conductive material 50;

7) step 707 — adaptive temperature controller 10 determines the resistance of electrically conductive material 50 at the received temperature;

8) step 708 — the adaptive temperature controller 10 receives an instruction from an operator or computer terminal 80 to change the temperature of the conductive material 50 to a specific temperature;

9) step 709 — adaptive temperature controller 10 determines the voltage associated with the temperature command received from the operator or computer terminal 80;

10) step 710-adaptive temperature controller 10 causes a voltage or current associated with the temperature command to be applied to conductive material 50.

Alternatively, as shown in fig. 8, the calibration of the conductive material 50 may be performed in the following steps:

1) step 801-stabilize the temperature of the conductive material 50 at ambient temperature or close to the high temperature at which the conductive material 50 will be used;

2) step 802 — measure the temperature of the conductive material 50 and output the measured temperature to the adaptive temperature controller 10;

3) step 803 — the measured temperature of the conductive material 50 enters the controller unit as a parameter;

4) step 804-the controller calculates a scaling factor for the measured temperature of the conductive material 50 from the relative resistance and the preset normalized resistance characteristic;

5) step 805 — input a temperature selection point for the measured temperature of the conductive material 50.

The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof.

Claims (9)

1. An adaptive temperature controller (10) for synchronized temperature measurement and control for use with an electrically conductive material (50) to heat a system component (101), comprising:

a temperature sensor (30) for detecting a temperature,

the temperature sensor (30) determines the temperature of the electrically conductive material (50);

a device for measuring the electrical resistance of a resistor,

the means for measuring resistance records measurements of two members of the group consisting of power, current, and voltage;

said means for measuring resistance determining the resistance of said conductive material (50) by applying ohm's law to two members of said group consisting of power, current and voltage;

a power supply for supplying power to the electronic device,

the power source is in electrical communication with the conductive material (50);

the conductive material (50) changes temperature based on the electrical communication from the power source;

means for controlling an output of the power supply,

the means for measuring the resistance outputs the determined resistance of the conductive material (50) to the means for controlling the output of the power supply,

said temperature sensor (30) outputting the determined temperature of said conductive material (50) to said means for controlling the output of said power source;

the means for controlling the output of the power supply determines a thermal resistance coefficient of the electrically conductive material (50) based on the output of the means for measuring resistance and the output of the temperature sensor (30);

the means for controlling the output of the power source controls the temperature of the electrically conductive material (50) based on the output of one of the group of power, voltage or current.

2. The adaptive temperature controller (10) of claim 1, further comprising a pulse width modulated switching power supply (11) controlled by a microcontroller or microprocessor (12).

3. The adaptive temperature controller (10) of claim 1, further comprising a fan (70) that induces air flow around the system component (101).

4. The adaptive temperature controller (10) of claim 2, further comprising a fan to induce air flow around the system component (101).

5. The adaptive temperature controller (10) of claim 1, wherein the adaptive temperature controller (10) is in communication with a computer.

6. The adaptive temperature controller (10) of claim 2, wherein the adaptive temperature controller (10) is in communication with a computer.

7. The adaptive temperature controller (10) of claim 4, wherein the adaptive temperature controller (10) is in communication with a computer.

8. A method of calibrating an adaptive temperature controller (10), wherein the adaptive temperature controller (10) is used to synchronize temperature measurements and controls for use with an electrically conductive material (50) to heat a system component (101), the adaptive temperature controller (10) comprising:

a temperature sensor (30) for detecting a temperature,

the temperature sensor (30) determines the temperature of the electrically conductive material (50);

a device for measuring the electrical resistance of a resistor,

the means for measuring resistance records measurements of two members of the group consisting of power, current, and voltage;

said means for measuring resistance determining the resistance of said conductive material (50) by applying ohm's law to two members of said group consisting of power, current and voltage;

a power supply for supplying power to the electronic device,

the power source is in electrical communication with the conductive material (50);

the conductive material (50) changes temperature based on the electrical communication from the power source;

means for controlling an output of the power supply,

the means for measuring the resistance outputs the determined resistance of the conductive material (50) to the means for controlling the output of the power supply,

said temperature sensor (30) outputting the determined temperature of said conductive material (50) to said means for controlling the output of said power source;

the means for controlling the output of the power supply determines a thermal resistance coefficient of the electrically conductive material (50) based on the output of the means for measuring resistance and the output of the temperature sensor (30); and

the means for controlling the output of the power source controls the temperature of the electrically conductive material (50) based on the output of one of the group of power, voltage or current,

the method comprises the following steps:

determining a material of the conductive material (50);

the adaptive temperature controller (10) obtains a normalized resistance of the conductive material (50);

stabilizing the temperature of the conductive material (50) at a predetermined temperature;

the adaptive temperature controller (10) provides a voltage or current to the conductive material (50) at least once and measures the current or voltage flowing therethrough;

the temperature sensor (30) measures the temperature of the electrically conductive material (50);

-the adaptive temperature controller (10) receives measurements of the temperature sensor (30);

the adaptive temperature controller (10) determining the resistance of the electrically conductive material at the measurement of the temperature sensor (30);

the adaptive temperature controller (10) receiving an instruction to change the temperature of the electrically conductive material (50) to a specific temperature;

the adaptive temperature controller (10) determining a voltage associated with the received temperature command;

the adaptive temperature controller (10) applies one of the group of voltage and current associated with a temperature command to the electrically conductive material (50).

9. A method of calibrating an adaptive temperature controller (10), wherein the adaptive temperature controller (10) is used to synchronize temperature measurements and controls for use with an electrically conductive material (50) to heat a system component (101), the adaptive temperature controller (10) comprising:

a temperature sensor (30) for detecting a temperature,

the temperature sensor (30) determines the temperature of the electrically conductive material (50);

a device for measuring the electrical resistance of a resistor,

the means for measuring resistance records measurements of two members of the group consisting of power, current, and voltage;

said means for measuring resistance determining the resistance of said conductive material (50) by applying ohm's law to two members of said group consisting of power, current and voltage;

a power supply for supplying power to the electronic device,

the power source is in electrical communication with the conductive material (50);

the conductive material (50) changes temperature based on the electrical communication from the power source; means for controlling an output of the power supply,

the means for measuring the resistance outputs the determined resistance of the conductive material (50) to the means for controlling the output of the power supply,

said temperature sensor (30) outputting the determined temperature of said conductive material (50) to said means for controlling the output of said power source;

the means for controlling the output of the power supply determines a thermal resistance coefficient of the electrically conductive material (50) based on the output of the means for measuring resistance and the output of the temperature sensor (30); and

the means for controlling the output of the power source controls the temperature of the electrically conductive material (50) based on the output of one of the group of power, voltage or current,

the method comprises the following steps:

stabilizing the temperature of the conductive material (50);

measuring the temperature of the conductive material (50);

outputting a measurement of the temperature of the electrically conductive material (50) to the adaptive temperature controller (10);

-inputting the measurement of the temperature of the electrically conductive material (50) as a parameter into the adaptive temperature controller (10);

-said adaptive temperature controller (10) calculating a scaling factor for said measurement of said temperature of said electrically conductive material (50) from a relative resistance and a preset normalized resistance characteristic; and

inputting at least one temperature set point for the measurement of the temperature of the electrically conductive material (50) into the adaptive temperature controller (10).