CN112162580A - Temperature control circuit - Google Patents
Temperature control circuit Download PDFInfo
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- CN112162580A CN112162580A CN202011011467.8A CN202011011467A CN112162580A CN 112162580 A CN112162580 A CN 112162580A CN 202011011467 A CN202011011467 A CN 202011011467A CN 112162580 A CN112162580 A CN 112162580A
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- G05D23/19—Control of temperature characterised by the use of electric means
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Abstract
The embodiment of the application discloses temperature control circuit, this circuit includes: the device comprises a switching power supply, a linear power supply, a TEC, a voltage and current monitoring limiting circuit, a PID compensation amplifying circuit, a temperature error feedback circuit and an MCU; wherein: the switching power supply and the linear power supply are used for providing a working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode; the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result and sending the comparison result to the MCU; the temperature error feedback circuit is used for monitoring a target temperature value of the TEC, determining a temperature difference value between the target temperature value and a preset temperature value, and sending the temperature difference value to the MCU and the PID compensation amplifying circuit; and the MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when controlling the PID compensation amplifying circuit to be in the first working mode.
Description
Technical Field
The application relates to the technical field of temperature control, in particular to a temperature control circuit.
Background
At present, with the rapid development of scientific technology and process technology, various precision instruments are widely applied. However, some precision instruments need a strict use environment when being used, and particularly have high requirements on the environmental temperature, for example, the precision instruments can only be guaranteed to work normally when being used in a constant temperature environment. At present, a Thermoelectric Cooler (TEC), also called a semiconductor Cooler, is commonly used in a common ambient temperature control circuit. The specific principle is as follows: by applying a lower dc voltage across the TEC, heat will flow from one end of the element to the other, at which time the temperature at one end of the TEC will decrease while the temperature at the other end will rise simultaneously, i.e. changing the direction of the current, changing the direction of the heat flow and transferring the heat to the other end. Thus, two functions of cooling and heating can be simultaneously realized on one TEC. Therefore, the TEC is commonly used in a temperature control circuit, and different driving circuits and control strategies play a crucial role in the temperature control effect.
At present, a driving circuit of a commonly used temperature control circuit is realized by a switching power supply or a linear power supply, and the problems that the realization mode of the current temperature control circuit is single and the stability and the safety of the current commonly used temperature control circuit are poor exist.
Content of application
In order to solve the above technical problem, an embodiment of the present application is expected to provide a temperature control circuit, which solves the problem of poor stability and safety of the current commonly used temperature control circuit, effectively ensures the stability and safety of the temperature control circuit, and enriches the implementation manners of the temperature control circuit.
The technical scheme of the application is realized as follows:
a temperature control circuit, the circuit comprising: the system comprises a switching power supply, a linear power supply, a thermoelectric refrigerator TEC, a voltage and current monitoring limiting circuit, a proportional-integral-derivative PID compensation amplifying circuit, a temperature error feedback circuit and a micro control unit MCU; wherein:
the switching power supply and the linear power supply are used for providing working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode;
the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result, and sending the comparison result to the MCU;
the temperature error feedback circuit is used for monitoring a target temperature value of the TEC, determining a temperature difference value between the target temperature value and a preset temperature value, and sending the temperature difference value to the MCU and the PID compensation amplifying circuit;
the MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when the PID compensation amplifying circuit is controlled to be in a first working mode; the first power supply parameter is a parameter of a working power supply provided by the switching power supply for the TEC, and the second power supply parameter is a parameter of a working power supply provided by the linear power supply for the TEC.
Optionally, the MCU is further configured to enable the PID compensation amplifying circuit based on the comparison result when the PID compensation amplifying circuit is controlled to be in the second operating mode, and control an output value of the PID compensation amplifying circuit based on the temperature difference value, so as to control a third power parameter of the switching power supply and a fourth power parameter of the linear power supply through the PID compensation amplifying circuit; the third power supply parameter is a parameter of the working power supply provided by the switching power supply for the TEC, and the fourth power supply parameter is a parameter of the working power supply provided by the linear power supply for the TEC.
Optionally, the MCU is configured to control a first power parameter of the switching power supply and a second power parameter of the linear power supply based on the comparison result and the temperature difference, and the control method includes:
and the MCU is used for processing the comparison result and the temperature difference value by adopting a PID algorithm and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply.
Optionally, a positive input end of the TEC is connected to an output end of the switching power supply, a negative input end of the TEC is connected to an output end of the linear power supply, a positive input end of the TEC is connected to a first input end of the voltage and current monitoring limiting circuit, and a negative input end of the TEC is connected to a second input end of the voltage and current monitoring limiting circuit;
the output end of the voltage and current monitoring limiting circuit is connected with the first input end of the MCU;
a first output end of the temperature error feedback circuit is connected with a second input end of the MCU, and a second output end of the temperature error feedback circuit is connected with a first input end of the PID compensation amplifying circuit;
a first output end of the MCU is connected with a first input end of the switching power supply, a second output end of the MCU is connected with a first input end of the linear power supply, and a third output end of the MCU is connected with a second input end of the PID;
and the first output end of the PID compensation amplifying circuit is connected with the second input end of the switching power supply, and the second output end of the PID compensation amplifying circuit is connected with the second input end of the linear power supply.
Optionally, the circuit further comprises: sampling a resistor; wherein:
one end of the sampling resistor is connected with the negative electrode input end of the TEC, the other end of the sampling resistor is connected with the output end of the linear power supply, and the other end of the sampling resistor is also connected with the third input end of the voltage and current monitoring and limiting circuit.
Optionally, when the TEC is in the heating mode, the MCU or the PID compensation amplifying circuit controls the linear power supply to provide a second power supply parameter value for the TEC as a first parameter value, and correspondingly, when the TEC is switched to the heating mode, the MCU or the PID compensation amplifying circuit controls the first power supply parameter of the switching power supply as the second parameter value, and adjusts the value of the first power supply parameter according to a first preset step value along with the heating time until the value of the first power supply parameter of the switching power supply is the first parameter value.
Optionally, in the process that the TEC is switched from the heating mode to the cooling mode, the MCU or the PID compensation amplifying circuit controls the linear power supply to gradually decrease the value of the second power parameter provided by the TEC from the first parameter value to the second parameter value according to a second preset step value, and the MCU or the PID compensation amplifying circuit controls the switching power supply to gradually decrease the value of the first power parameter provided by the TEC from the first parameter value to the second parameter value according to the second preset step value.
Optionally, when the TEC is in the cooling mode, the MCU or the PID compensation amplifying circuit controls the linear power supply to provide the second power parameter value for the TEC, and correspondingly, when the TEC is switched to the cooling mode, the MCU or the PID compensation amplifying circuit controls the first power parameter of the switching power supply to start from the second power parameter value, and adjust the value of the first power parameter according to a third preset step value until the value of the first power parameter of the switching power supply is the first parameter value.
Optionally, the switching power supply comprises a buck switching power supply.
Optionally, the switching power supply includes a Source current mode and a Sink current mode, and the operating mode of the linear power supply includes the Source current mode and the Sink current mode.
The embodiment of the application provides a temperature control circuit, which comprises a switching power supply, a linear power supply, a thermoelectric refrigerator TEC, a voltage and current monitoring limiting circuit, a PID compensation amplifying circuit, a temperature error feedback circuit and a micro control unit MCU, wherein the switching power supply and the linear power supply are used for providing a working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode; the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result and sending the comparison result to the MCU; the temperature error feedback circuit is used for monitoring a target temperature value of the TEC, determining a temperature difference value between the target temperature value and a preset temperature value, and sending the temperature difference value to the MCU and the PID compensation amplifying circuit; and the MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when controlling the PID compensation amplifying circuit to be in the first working mode. Therefore, the TEC is driven to work by the switching power supply and the linear power supply simultaneously, the problem that the stability and the safety of the temperature control circuit commonly used at present are poor is solved, the stability and the safety of the temperature control circuit are effectively guaranteed, and the implementation mode of the temperature control circuit is enriched.
Drawings
Fig. 1 is a schematic structural diagram of a temperature control circuit according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of another temperature control circuit provided in the embodiment of the present application;
fig. 3 is a schematic diagram illustrating a relationship between output voltages and PID compensation outputs of a switching power supply and a linear power supply according to an embodiment of the present disclosure;
fig. 4 is a schematic diagram of a hardware circuit structure of a temperature error feedback circuit and a PID compensation amplifying circuit provided in an embodiment of the present application;
fig. 5 is a schematic diagram of a hardware circuit structure of a voltage-current monitoring limiting circuit according to an embodiment of the present disclosure.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
The embodiment of the application provides a temperature control circuit, which comprises a switching power supply, a linear power supply, a thermoelectric refrigerator TEC, a voltage and current monitoring limiting circuit, a proportional-integral-derivative PID compensation amplifying circuit, a temperature error feedback circuit and a micro control unit MCU; wherein:
and the switching power supply and the linear power supply are used for providing working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode.
In the embodiment of the application, the switching power supply and the linear power supply are adopted to simultaneously provide the working power supply for the TEC, so that the switching power supply and the linear power supply are used to simultaneously provide the working power supply for the TEC, and the stability and the safety of the temperature control circuit are ensured.
And the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result, and sending the comparison result to the MCU.
In this embodiment of the application, the preset parameter includes a heating preset parameter and a cooling preset parameter, and the corresponding comparison result includes that the working parameter of the TEC is between the heating preset parameter and the cooling preset parameter, or the working parameters at two ends of the TEC are greater than the cooling preset parameter, or the working voltages at two ends of the TEC are less than the heating preset parameter, and the like. The working parameters of the TEC can be working voltages at two ends of the TEC, and the corresponding preset parameters comprise a heating preset voltage parameter and a refrigerating preset voltage parameter; the working parameter of the TEC can also be the working current of the TEC, and the corresponding preset parameters comprise a heating preset current parameter and a refrigerating preset current parameter; or the working parameters of the TEC are the working current of the TEC and the working voltage at two ends of the TEC, and the corresponding preset parameters comprise a heating preset voltage parameter, a refrigerating preset voltage parameter, a heating preset current parameter and a refrigerating preset current parameter.
And the temperature error feedback circuit is used for monitoring the target temperature value of the TEC, determining the temperature difference between the target temperature value and the preset temperature value, and sending the temperature difference to the MCU and the PID compensation amplifying circuit.
In this embodiment of the present application, the component used for monitoring the target temperature value of the TEC in the temperature error feedback circuit may be a thermistor, that is, the thermistor may be attached to the TEC, or may be a certain distance value away from the TEC. In some application scenarios, the target temperature value of the TEC detected by the temperature error feedback circuit may be represented by voltage, current, or the like, and the corresponding preset temperature value may also be a preset voltage or a preset current. The temperature difference is used for being processed through an MCU or a PID compensation amplifying circuit, so that the output voltage or the output current provided by the switching power supply and the linear power supply for the TEC is further automatically adjusted, and the target temperature value of the TEC is controlled to be close to the preset temperature value.
The MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when the PID compensation amplifying circuit is controlled to be in a first working mode; the first power supply parameter is a parameter of a working power supply provided by the switching power supply for the TEC, and the second power supply parameter is a parameter of the working power supply provided by the linear power supply for the TEC.
In the embodiment of the application, the operation mode of the PID compensation amplifying circuit includes operation of the PID compensation amplifying circuit and stop of the PID compensation amplifying circuit, wherein the first operation mode of the PID compensation amplifying circuit is stop of the PID compensation amplifying circuit. At this time, the comparison result and the temperature difference value can be operated through an algorithm program operated in the MCU, so as to realize the function of the PID compensation amplifying circuit, and thus control the first power parameter of the switching power supply and the second power parameter of the linear power supply, that is, the first power parameter of the switching power supply and the second power parameter of the linear power supply are controlled in a software manner. The first power supply parameter may be an output voltage and/or an output current of the switching power supply and the second power supply parameter may be an output voltage and/or an output current of the linear power supply.
The temperature control circuit provided by the embodiment of the application comprises a switching power supply, a linear power supply, a thermoelectric refrigerator TEC, a voltage and current monitoring limiting circuit, a PID compensation amplifying circuit, a temperature error feedback circuit and a micro control unit MCU, wherein the switching power supply and the linear power supply are used for providing a working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode; the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result and sending the comparison result to the MCU; the temperature error feedback circuit is used for monitoring a target temperature value of the TEC, determining a temperature difference value between the target temperature value and a preset temperature value, and sending the temperature difference value to the MCU and the PID compensation amplifying circuit; and the MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when controlling the PID compensation amplifying circuit to be in the first working mode. Therefore, the TEC is driven to work by the switching power supply and the linear power supply simultaneously, the problem that the stability and the safety of the temperature control circuit commonly used at present are poor is solved, the stability and the safety of the temperature control circuit are effectively guaranteed, and the implementation mode of the temperature control circuit is enriched.
Based on the foregoing embodiments, an embodiment of the present application provides a temperature control circuit, where the circuit includes a switching power supply, a linear power supply, a thermoelectric cooler TEC, a voltage and current monitoring limiting circuit, a proportional-integral-derivative PID compensation amplifying circuit, a temperature error feedback circuit, and a micro control unit MCU; wherein:
the switching power supply and the linear power supply are used for providing a working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode; the switching power supply comprises a voltage-reducing switching power supply, the switching power supply comprises a Source current Source mode and a Sink current mode, and the working mode of the linear power supply comprises the Source current Source mode and the Sink current mode.
And the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result, and sending the comparison result to the MCU.
And the temperature error feedback circuit is used for monitoring the target temperature value of the TEC, determining the temperature difference between the target temperature value and the preset temperature value, and sending the temperature difference to the MCU and the PID compensation amplifying circuit.
The MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when the PID compensation amplifying circuit is controlled to be in a first working mode; the first power supply parameter is a parameter of a working power supply provided by the switching power supply for the TEC, and the second power supply parameter is a parameter of the working power supply provided by the linear power supply for the TEC.
In other embodiments of the present application, the MCU is configured to control a first power parameter of the switching power supply and a second power parameter of the linear power supply based on the comparison result and the temperature difference, and the control method includes:
and the MCU is used for processing the comparison result and the temperature difference value by adopting a PID algorithm and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply.
In the embodiment of the application, the MCU runs an algorithm program for realizing PID calculation.
The MCU is also used for enabling the PID compensation amplifying circuit based on the comparison result when controlling the PID compensation amplifying circuit to be in the second working mode, and controlling the output value of the PID compensation amplifying circuit based on the temperature difference value so as to control the third power supply parameter of the switching power supply and the fourth power supply parameter of the linear power supply through the PID compensation amplifying circuit; the third power supply parameter is a parameter of the working power supply provided by the switching power supply for the TEC, and the fourth power supply parameter is a parameter of the working power supply provided by the linear power supply for the TEC.
In the embodiment of the present application, the PID compensation amplifying circuit is in the second operation mode, that is, the PID compensation amplifying circuit operates, that is, the mode in which software is not enabled to realize the function of the PID compensation amplifying circuit. The temperature control circuit also comprises: a software implementation method for realizing the function of the PID compensation amplifying circuit and a hardware implementation process of the PID compensation amplifying circuit.
In other embodiments of the present application, a schematic diagram of a connection structure of a temperature control circuit may be shown in fig. 1, where the temperature control circuit includes: the system comprises a switching power supply 11, a linear power supply 12, a thermoelectric refrigerator TEC 13, a voltage and current monitoring and limiting circuit 14, a temperature error feedback circuit 15, a proportional-integral-derivative PID compensation amplifying circuit 16 and a micro control unit MCU 17; wherein:
the positive input end of the TEC is connected with the output end of the switching power supply, the negative input end of the TEC is connected with the output end of the linear power supply, the positive input end of the TEC is connected with the first input end of the voltage and current monitoring limiting circuit, and the negative input end of the TEC is connected with the second input end of the voltage and current monitoring limiting circuit;
the output end of the voltage and current monitoring limiting circuit is connected with the first input end of the MCU;
the first output end of the temperature error feedback circuit is connected with the second input end of the MCU, and the second output end of the temperature error feedback circuit is connected with the first input end of the PID compensation amplifying circuit;
a first output end of the MCU is connected with a first input end of the switching power supply, a second output end of the MCU is connected with a first input end of the linear power supply, and a third output end of the MCU is connected with a second input end of the PID;
and a first output end of the PID compensation amplifying circuit is connected with a second input end of the switching power supply, and a second output end of the PID compensation amplifying circuit is connected with a second input end of the linear power supply.
In other embodiments of the present application, referring to fig. 2, the temperature control circuit further includes: a sampling resistor 18; wherein:
one end of the sampling resistor is connected with the negative electrode input end of the TEC, the other end of the sampling resistor is connected with the output end of the linear power supply, and the other end of the sampling resistor is also connected with the third input end of the voltage and current monitoring and limiting circuit.
In other embodiments of the present application, when the TEC is in the heating mode, the MCU or the PID compensation amplifying circuit controls the value of the second power parameter provided by the linear power supply for the TEC to be the first parameter value, and correspondingly, when the TEC is switched to the heating mode, the MCU or the PID compensation amplifying circuit controls the first power parameter of the switching power supply to be the second parameter value, and adjusts the value of the first power parameter according to the first preset step value along with the heating time until the value of the first power parameter of the switching power supply is the first parameter value.
In other embodiments of the present application, in a process of switching the TEC from the heating mode to the cooling mode, the MCU or the PID compensation amplifying circuit controls the linear power supply to gradually decrease the value of the second power parameter provided by the TEC from the first parameter value to the second parameter value according to a second preset step value, and the MCU or the PID compensation amplifying circuit controls the switching power supply to gradually decrease the value of the first power parameter provided by the TEC from the first parameter value to the second parameter value according to the second preset step value.
In other embodiments of the present application, when the TEC is in the cooling mode, the MCU or the PID compensation amplifying circuit controls the value of the second power parameter provided by the linear power supply for the TEC to be the second parameter value, and correspondingly, when the TEC is switched to the cooling mode, the MCU or the PID compensation amplifying circuit controls the first power parameter of the switching power supply to start from the second parameter value, and adjusts the value of the first power parameter according to the third preset step value until the value of the first power parameter of the switching power supply is the first parameter value.
Based on the foregoing embodiments, the present application provides a temperature control circuit, and the structure of the temperature control circuit can refer to fig. 2. In the temperature control circuit provided in the embodiment of the present application, the mode of controlling the working process of the TEC includes two modes, one is a software control mode and the other is a hardware control mode, that is, the function of the PID compensation amplifying circuit may be implemented by software or hardware. Wherein:
in the software control mode, the MCU is the control body, and the driving current of the TEC can be supplied through the buck switching power supply and the linear power supply. When the MCU controls the buck switching power supply and the linear power supply, the MCU provides Digital-Analog (DA) quantity to automatically adjust the output voltage of the switching power supply, and the MCU controls the output voltage of the linear power supply, so that the switching between the heating mode and the cooling mode of the TEC is controlled through the linear power supply. As shown in fig. 2, the linear power supply is connected to the negative electrode of the TEC, and correspondingly, when the TEC is controlled to be in the heating mode, the VCC rail of the linear power supply is controlled, that is, the forward power supply voltage is provided, and when the TEC is in the heating mode, the GND rail of the linear power supply is controlled, that is, the ground of the linear power supply is controlled.
In order to ensure the stability of the working current passing through the TEC in the zero point switching process, i.e., the switching process between the two heating modes, the output voltage of the linear power supply and the output voltage of the switching power supply need to be the same in the zero point switching process. The temperature error feedback circuit collects the current temperature of the TEC through a thermistor arranged near the TEC, performs error amplification, obtains a Digital temperature value through Analog-to-Digital Converter (ADC) conversion and feeds the Digital temperature value back to the MCU, the MCU executes a software PID compensation algorithm based on the Digital temperature value and a preset temperature value, and outputs a control quantity obtained through Digital-to-Analog Converter (DAC) to control the switching power supply and the linear power supply so as to complete automatic locking of the TEC temperature. Meanwhile, the MCU monitors the voltage value of the positive end and the negative end of the TEC acquired by the voltage and current monitoring limiting circuit and the voltage value of the high-precision sampling resistor with the sampling value of 0.1 ohm (omega), monitors the voltage and the current of the TEC in real time, and limits the voltage and the current of the TEC according to the voltage and the current.
When the voltage and current monitoring and limiting circuit collects the working voltage of the TEC, the voltages at the positive end and the negative end of the TEC are collected respectively, the working voltage of the TEC can be obtained through differential conversion of the operational amplifier, or the voltages at the positive end and the negative end of the TEC are subjected to differential processing directly through the MCU, so that the current working voltage of the TEC is obtained.
In a hardware control mode, the main part is the same as a software control mode, but the PID compensation amplifying circuit is composed of an operational amplifier and a pure resistor-capacitor element, and a preset temperature value is provided by an external DAC or an adjustable resistor. The voltage of the switching power supply and the linear power supply is controlled by the hardware PID output quantity.
In the embodiment of the application, both the switch power supply and the linear power supply can work between VCC and GND, and can work in a Sink mode and a Source mode at the same time;
the voltage output of the switching power supply and the linear power supply can be controlled by a DAC of the MCU, namely PID compensation or hardware PID compensation output control is realized by MCU software, and the two are compatible. The relationship between the output voltage of the switching power supply and the linear power supply and the PID compensation output is shown in FIG. 3, the ordinate is the voltage output, and the abscissa is the working state of the TEC. Wherein, A is PID compensation output corresponding to the linear power supply, B is PID compensation corresponding to the switching power supply, C is total PID compensation output obtained according to the linear power supply and the switching power supply, and the working state of the TEC represented by the abscissa comprises a heating mode a1, a zero switching mode a2 and a cooling mode a 3.
The hardware circuit structures of the temperature error feedback circuit and the PID compensation amplifying circuit may be specifically shown in fig. 4, where D is the temperature error feedback circuit portion, and E is the PID compensation amplifying circuit portion. In the temperature error feedback circuit D, VREF is used to represent a reference voltage, which is an empirical value set according to actual conditions, R is a voltage dividing resistor, RTH is used to represent a thermistor, and D1 is an error amplifier; in the PID compensation amplifying circuit E, Z1 and Z2 are two resistors, E1 is a differential amplifier, and E2 is a PID compensation output. Wherein:
(1) the thermistor RTH and the divider resistor R are used for dividing the reference voltage VREF, and the resistance value of the thermistor RTH changes along with the change of temperature, so that a temperature sampling value obtained by sampling of the thermistor and the temperature of the TEC have a one-to-one correspondence relationship. (2) After the voltage of the thermistor RTH and VREF/2 enter the error amplifier D1, the error amplifier D1 outputs a temperature error value to the PID compensation amplifying circuit for operation. (3) The temperature error of the thermistor and the preset temperature value set by the MCU are compared by the error amplifier D1 and then are calculated by the PID compensation amplifying circuit to obtain the PID compensation output E2, so that the PID compensation output E2 is used for controlling the DA output of the MCU to realize the control of the voltage output quantity of the switching power supply and the linear power supply, and the automatic control of the TEC temperature is realized.
It should be noted that, the PID compensation amplifying circuit E can be realized by hardware after the PID compensation amplifying circuit is realized, and the MCU can execute a software PID algorithm to ensure fast and stable control of the PID compensation output parameter.
The voltage and current monitoring and limiting circuit comprises the following steps:
1) the voltage difference of the positive end and the negative end of the TEC is collected, converted by the operational amplifier and sent to the MCU, so that the working voltage value of the TEC is monitored in real time; the TEC current is acquired through a 0.1 omega high-precision sampling resistor and is transmitted to the MCU after being converted by the operational amplifier, so that the TEC working current value is monitored in real time.
2) The TEC voltage current limitation may be implemented by software, that is, the MCU compares the collected TEC working voltage value with a preset voltage value, and/or compares the collected TEC working current value with a preset current value, so as to obtain a comparison result. Or, the method can also be implemented by hardware, that is, the collected TEC working voltage value is compared with a preset voltage value by a comparator, and the collected TEC working current value is compared with a preset current value by the comparator to obtain a comparison result. And then controlling a control source of a TEC driving power supply (a switching power supply and a linear power supply), namely a PID compensation amplifying circuit, according to a comparison result obtained by software implementation or a comparison result obtained by hardware implementation.
The control of the heating mode and the cooling mode of the TEC can be implemented by two comparators, as shown in fig. 5, when the comparators G1 and G2 determine that the monitored value (including the operating voltage value and/or the operating current value of the TEC) of the voltage and current monitoring limiting circuit is between the cooling threshold value and the heating threshold value, two subtracters H1 and H2 are turned off, and the PID compensation amplifying circuit I is enabled to control the TEC driving power supply J, which includes a switching power supply and a linear power supply, and the circuit normally operates in the TEC locking mode; when the comparators G1 and G2 determine that the monitoring value of the voltage and current monitoring limiting circuit is larger than the refrigeration threshold value, the refrigeration output turns off the PID compensation amplifying circuit I, the refrigeration subtracter H1 is enabled to output the difference between the monitoring value and the threshold value to the output end of the PID compensation amplifying circuit to control the TEC driving power supply J, and the larger the difference is, the smaller the output of the TEC driving power supply J is, so that the voltage and the current of the TEC are limited; when the comparators G1 and G2 determine that the monitoring value of the voltage and current monitoring limiting circuit is smaller than the heating threshold value, the PID compensation amplifying circuit I is also turned off, the heating subtracter H2 is turned on, the difference between the monitoring value and the threshold value is output to the output end of the PID compensation amplifying circuit to control the TEC driving power supply J, the larger the difference is, the smaller the TEC driving power supply J is, and the TEC current direction is reversed at the moment.
It should be noted that, for the descriptions of the same contents in this embodiment as in the other embodiments, reference may be made to the descriptions in the other embodiments, and details are not described here again.
The temperature control circuit provided by the embodiment of the application comprises a switching power supply, a linear power supply, a thermoelectric refrigerator TEC, a voltage and current monitoring limiting circuit, a PID compensation amplifying circuit, a temperature error feedback circuit and a micro control unit MCU, wherein the switching power supply and the linear power supply are used for providing a working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode; the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result and sending the comparison result to the MCU; the temperature error feedback circuit is used for monitoring a target temperature value of the TEC, determining a temperature difference value between the target temperature value and a preset temperature value, and sending the temperature difference value to the MCU and the PID compensation amplifying circuit; and the MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when controlling the PID compensation amplifying circuit to be in the first working mode. Therefore, the TEC is driven to work by the switching power supply and the linear power supply simultaneously, the problem that the stability and the safety of the temperature control circuit commonly used at present are poor is solved, the stability and the safety of the temperature control circuit are effectively guaranteed, and the implementation mode of the temperature control circuit is enriched. By combining a driving circuit of a switching power supply and a linear power supply, the MCU is used for automatically controlling the TEC, and meanwhile, the mode of being compatible with the software PID and the hardware PID achieves the automatic control mode of the TEC temperature, so that the temperature control circuit and the control mode are simple and reliable, the power supply efficiency is ensured, and the stability of the zero crossing point of the circuit is also ensured.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the present application.
Claims (10)
1. A temperature control circuit, the circuit comprising: the system comprises a switching power supply, a linear power supply, a thermoelectric refrigerator TEC, a voltage and current monitoring limiting circuit, a proportional-integral-derivative PID compensation amplifying circuit, a temperature error feedback circuit and a micro control unit MCU; wherein:
the switching power supply and the linear power supply are used for providing working power supply for the TEC so as to control the TEC to realize a heating mode or a cooling mode;
the voltage and current monitoring limiting circuit is used for monitoring the working parameters of the TEC, comparing the working parameters with preset parameters to obtain a comparison result, and sending the comparison result to the MCU;
the temperature error feedback circuit is used for monitoring a target temperature value of the TEC, determining a temperature difference value between the target temperature value and a preset temperature value, and sending the temperature difference value to the MCU and the PID compensation amplifying circuit;
the MCU is used for controlling the working mode of the PID compensation amplifying circuit, and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply based on the comparison result and the temperature difference value when the PID compensation amplifying circuit is controlled to be in a first working mode; the first power supply parameter is a parameter of a working power supply provided by the switching power supply for the TEC, and the second power supply parameter is a parameter of a working power supply provided by the linear power supply for the TEC.
2. The circuit of claim 1,
the MCU is also used for enabling the PID compensation amplifying circuit based on the comparison result and controlling the output value of the PID compensation amplifying circuit based on the temperature difference value when the PID compensation amplifying circuit is controlled to be in a second working mode so as to control a third power supply parameter of the switching power supply and a fourth power supply parameter of the linear power supply through the PID compensation amplifying circuit; the third power supply parameter is a parameter of the working power supply provided by the switching power supply for the TEC, and the fourth power supply parameter is a parameter of the working power supply provided by the linear power supply for the TEC.
3. The circuit of claim 1, wherein the MCU is configured to control a first power parameter of the switching power supply and a second power parameter of the linear power supply based on the comparison result and the temperature difference, and comprises:
and the MCU is used for processing the comparison result and the temperature difference value by adopting a PID algorithm and controlling a first power supply parameter of the switching power supply and a second power supply parameter of the linear power supply.
4. The circuit of claim 1,
the positive input end of the TEC is connected with the output end of the switching power supply, the negative input end of the TEC is connected with the output end of the linear power supply, the positive input end of the TEC is connected with the first input end of the voltage and current monitoring and limiting circuit, and the negative input end of the TEC is connected with the second input end of the voltage and current monitoring and limiting circuit;
the output end of the voltage and current monitoring limiting circuit is connected with the first input end of the MCU;
a first output end of the temperature error feedback circuit is connected with a second input end of the MCU, and a second output end of the temperature error feedback circuit is connected with a first input end of the PID compensation amplifying circuit;
a first output end of the MCU is connected with a first input end of the switching power supply, a second output end of the MCU is connected with a first input end of the linear power supply, and a third output end of the MCU is connected with a second input end of the PID;
and the first output end of the PID compensation amplifying circuit is connected with the second input end of the switching power supply, and the second output end of the PID compensation amplifying circuit is connected with the second input end of the linear power supply.
5. The circuit of claim 4, further comprising: sampling a resistor; wherein:
one end of the sampling resistor is connected with the negative electrode input end of the TEC, the other end of the sampling resistor is connected with the output end of the linear power supply, and the other end of the sampling resistor is also connected with the third input end of the voltage and current monitoring and limiting circuit.
6. The circuit according to any of claims 1 to 5,
when the TEC is in the heating mode, the MCU or the PID compensation amplifying circuit controls the linear power supply to provide a second power supply parameter value for the TEC as a first parameter value, and correspondingly, when the TEC is switched to the heating mode, the MCU or the PID compensation amplifying circuit controls the first power supply parameter of the switching power supply as the second parameter value, and adjusts the value of the first power supply parameter according to a first preset step value along with the heating time until the value of the first power supply parameter of the switching power supply is the first parameter value.
7. The circuit of claim 6,
in the process that the TEC is switched from the heating mode to the cooling mode, the MCU or the PID compensation amplifying circuit controls the linear power supply to gradually reduce the value of the second power supply parameter provided by the TEC from the first parameter value to the second parameter value according to a second preset step value, and the MCU or the PID compensation amplifying circuit controls the switching power supply to gradually reduce the value of the first power supply parameter provided by the TEC from the first parameter value to the second parameter value according to the second preset step value.
8. The circuit of claim 7,
when the TEC is in the cooling mode, the MCU or the PID compensation amplifying circuit controls the linear power supply to provide the second power parameter value for the TEC, and correspondingly, when the TEC is switched to the cooling mode, the MCU or the PID compensation amplifying circuit controls the first power parameter of the switching power supply to adjust the value of the first power parameter according to a third preset step value from the second power parameter value until the value of the first power parameter of the switching power supply is the first parameter value.
9. The circuit according to any of claims 1 to 5,
the switching power supply includes a step-down switching power supply.
10. The circuit according to any of claims 1 to 5,
the switching power supply comprises a Source current mode and a Sink current mode, and the working mode of the linear power supply comprises the Source current mode and the Sink current mode.
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| CN202011011467.8A CN112162580A (en) | 2020-09-23 | 2020-09-23 | Temperature control circuit |
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| CN202011011467.8A CN112162580A (en) | 2020-09-23 | 2020-09-23 | Temperature control circuit |
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Application publication date: 20210101 |