A temperature control system

Abstract

The application discloses a temperature control system, which comprises a controller, a power supply polarity switching module, an RC filter circuit, a power supply module, a refrigeration device and a temperature sensor; the controller is used for outputting a power regulation signal; the RC filter circuit is connected with the controller; the RC filter circuit is used for converting the power regulation signal into a direct current level and inputting the power supply module; the direct current level is used for controlling the output voltage of the power supply module; the power supply polarity switching module is connected with the controller and the refrigeration device respectively; the controller is used for switching the power supply polarity of the electrode of the refrigeration device through the power supply polarity switching module based on the current temperature detected by the temperature sensor, so that the working mode of the refrigeration device is controlled to be in a refrigeration mode or a heating mode. In the above scheme, the power regulation signal (a PWM signal or a DAC signal) and the RC control output low ripple direct current are used for driving the refrigeration device, and the driving mode has high heat conversion efficiency, and compared with pulse driving, the service life of the refrigeration device can be greatly prolonged.

Description

Technical Field

[0001] This invention relates to the field of projection display, and more particularly to a temperature control system. Background Technology

[0002] A TEC (Thermoelectric Cooler) is a cooling technology based on the Peltier effect. When current flows through the interface of two different conductors, one end absorbs heat (cooling) and the other end releases heat (heating). PWM (Pulse Width Modulation) controls the average current or average voltage of the TEC through high-speed switching and duty cycle modulation, thereby regulating the TEC's power and operating mode (cooling or heating).

[0003] In existing conventional driving methods, the opening and closing of the control switch generates a square wave. When the switch is on, the switch outputs a high level, driving current flows through the TEC (Transformer Controlled Cooling Device), and the TEC is in operation, performing cooling or heating. When the switch is off, there is no output, and the TEC is in the off state.

[0004] In the above scheme, the TEC only operates in two pulse modes: on and off. By controlling different on and off times, different power outputs are achieved to reach the stable temperature required by the TEC. Since the TEC only operates in two states—full power output and zero power output—the instantaneous temperature fluctuation of the controlled object is relatively large in this operating mode. Furthermore, due to the characteristics of the TEC, this excitation method results in extremely low TEC conversion efficiency, with most of the power being converted into heat generation from the hot surface. Summary of the Invention

[0005] The purpose of this invention is to provide a temperature control system that solves the technical problem of extremely low TEC conversion efficiency in the prior art.

[0006] To achieve the above-mentioned objectives, a first aspect of the present invention provides a temperature control system, the system comprising: a controller, a power supply polarity switching module, an RC filter circuit, a power supply module, a refrigeration device, and a temperature sensor;

[0007] The controller is used to output a power regulation signal;

[0008] The RC filter circuit is connected to the controller; the RC filter circuit is used to convert the power regulation signal into a DC level and input it to the power supply module; the DC level is used to control the output voltage of the power supply module.

[0009] The electrode polarity switching module is connected to the controller and the cooling device respectively. The controller is used to switch the electrode polarity of the cooling device through the electrode polarity switching module based on the current temperature detected by the temperature sensor, so as to control the working mode of the cooling device to be either cooling mode or heating mode.

[0010] Optionally, the cooling device is a thermoelectric cooler (TEC).

[0011] Optionally, the controller is configured to control the power regulation signal to maintain its current state after the current temperature detected by the temperature sensor reaches the target temperature, so as to maintain the output voltage value of the power module constant.

[0012] Optionally, the power adjustment signal is a pulse width modulation (PWM) signal; the controller is used to control the duty cycle of the PWM signal to adjust the DC level value corresponding to the PWM signal.

[0013] Optionally, the power adjustment signal is a DAC signal; the controller is used to control the level of the DAC signal.

[0014] Optionally, the power module is a BUCK type power supply, a BOOST type power supply, or a BUCK-BOOST type power supply.

[0015] One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0016] In the embodiment of the present invention, PWM and RC filtering are used to control the power module to generate low-ripple DC to drive the cooling device. This driving method has high thermal conversion efficiency and can significantly extend the service life of the cooling device compared with pulse driving. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the temperature control system provided in an embodiment of the present invention;

[0019] Figure 2 A schematic diagram of a power supply provided in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of the LC filtering scheme provided in an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of a power supply polarity switching module provided in an embodiment of the present invention;

[0022] Figure 5 This is a schematic diagram of another temperature control system provided in an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a temperature control system in an embodiment of the present invention. The temperature control system includes a controller 101, a power supply polarity switching module 102, an RC filter circuit 103, a power supply module 104, a cooling device 105, and a temperature sensor 106. The controller 101 is used to output a power adjustment signal. The RC filter circuit 103 is connected to the controller 101. The RC filter circuit 103 is used to convert the power adjustment signal into a DC level and input it to the power supply module 104. The DC level is used to control the output voltage of the power supply module 104. The power supply polarity switching module 102 is connected to the controller 101 and the cooling device 105 respectively. The controller 101 is used to switch the power supply polarity of the electrodes of the cooling device 105 through the power supply polarity switching module 102 based on the current temperature detected by the temperature sensor 106, so as to control the working mode of the cooling device 105 to be either cooling mode or heating mode.

[0025] In this embodiment of the invention, it is assumed that the cooling device 105 is a TEC (Cooling Device). The conversion power of the TEC is provided by the TEC's power supply. According to the characteristics of the TEC, the thermal conversion efficiency of the TEC is highest when directly driven by a DC signal. Therefore, in the scheme of this embodiment of the invention, a low-ripple DC signal is directly output from a DC power supply to power the TEC. The power supply module can be a BUCK type power supply, a BOOST type power supply, or a BUCK-BOOST type power supply, etc. Simultaneously, according to the temperature control algorithm, the supply voltage of the power supply module is dynamically adjusted to adjust the heating or cooling power of the TEC, thereby achieving the purpose of stabilizing the temperature.

[0026] In this embodiment of the invention, the controller generates a power regulation signal for controlling the output of the DC power supply. The power regulation signal can be a PWM pulse modulation signal that has been RC filtered, or it can be a DC analog signal directly output by the controller with a DAC module. The DAC module can be a built-in module of the controller or an external module; this invention does not impose any restrictions on this.

[0027] In this embodiment of the invention, a DC / DC (power module converter) BUCK power supply (hereinafter referred to as BUCK power supply) is used as an example for explanation. Figure 2 As shown, the output voltage of the BUCK power supply is determined by the voltage of its feedback pin. When the power regulation signal is a PWM signal, the controller outputs one PWM signal, which is then converted into a DC level after RC filtering. By controlling the duty cycle of the PWM signal, the DC level can be adjusted. When the power regulation signal is a DAC signal, the controller controls the DAC module to output signals of different amplitudes, which are then filtered by an RC filter to adjust the output power. These different DC levels are then input to the feedback pin of the BUCK power supply to control the corresponding output voltage, thereby adjusting the heating or cooling power of the TEC. Figure 2 In this case, the feedback network can be implemented using a resistor voltage divider.

[0028] Next, the system control principle in this embodiment of the invention will be explained. When the current temperature detected by the temperature sensor deviates from the target temperature, the controller changes the PWM duty cycle or DAC level to adjust the output voltage of the BUCK power supply. After reaching the target temperature, the current PWM duty cycle or DAC level is maintained, and the output voltage remains constant. Under unchanged external thermal load, the system reaches a stable state. At this time, the power module output value is stable with minimal ripple, the TEC heating or cooling power is stable, and the temperature remains constant with almost no fluctuation, thus achieving extremely high-precision temperature control.

[0029] Furthermore, BUCK power supplies operate at high frequencies, requiring small inductance values, typically in the μH range. For the same size, a lower ESR (Equivalent Series Resistance) value in a BUCK power supply results in less inductor heat generation. The smaller inductor size also makes it suitable for high-power applications, advantageous in space-constrained consumer electronics. For high-power heating or cooling scenarios, simply select a high-power BUCK power supply based on the corresponding maximum power requirement.

[0030] In this embodiment of the invention, in order to improve the thermal conversion efficiency of the TEC, it is necessary to filter out the high-frequency components of the switching pulse signal driving the TEC and output a stable current that approximates DC. The reason for using a power regulation signal (PWM signal / DAC signal) and an RC filtering scheme (hereinafter referred to as the RC filtering scheme) is that the RC filtering scheme has significant advantages over the PWM and LC filtering schemes (hereinafter referred to as the LC filtering scheme).

[0031] like Figure 3 As shown, the LC filtering scheme still uses a PWM signal for driving, but compared to the scheme using direct PWM driving, the driving current of the LC filtering scheme is no longer a pulse switching signal; the actual driving current is related to the LC parameters. To constrain the driving ripple current to a level similar to DC driving, the selected inductance value will reach over mH. Since the operating current required for TEC driving is relatively large, for inductors with large inductance values ​​and high current, the inductor volume is very large to reduce its ESR parameter. Excessive ESR leads to severe inductor heating, significantly reducing the efficiency of the driving circuit. Furthermore, although the ripple current of the output signal of the LC filtering scheme is greatly improved compared to the scheme using direct PWM driving, it is still larger than that of direct DC driving, resulting in low TEC conversion efficiency and a short lifespan when using the LC filtering scheme.

[0032] In the RC filtering scheme of this invention, the PWM signal / DAC signal, RC filter and power module generate low ripple current for driving, so the above-mentioned problem does not exist. For the RC filtering scheme, the required inductance value is small, generally at the uH level. The whole power supply scheme is small in size, has high power conversion efficiency, and has the advantages of convenient output and low cost.

[0033] In this embodiment of the invention, the electrode polarity switching module 102 can employ an H-bridge. Based on the characteristics of the TEC (Thermal Design Device), when the electrode polarity of the two electrodes of the TEC is controlled, the TEC can perform heating and cooling functions, corresponding to heating mode and cooling mode, respectively. For example, when the positive electrode of the TEC is connected to the power supply and the negative electrode is grounded, the TEC is in cooling mode. Conversely, when the positive electrode of the TEC is grounded and the negative electrode is connected to the power supply, the cold and hot sides of the TEC will be swapped, and the TEC will switch to heating mode. The function of the H-bridge is to dynamically change the operating mode of the TEC by dynamically switching the electrode polarity of the TEC electrode.

[0034] Please refer to Figure 4This is a schematic diagram of the H-bridge circuit, consisting of four power MOSFETs. When Q1 and Q4 are on, and Q3 and Q2 are off, current flows from VCC through Q1, from the left end of the load, through Q4, and into ground. When Q2 and Q3 are on, and Q1 and Q4 are off, current flows from VCC through Q3, from the right end of the load, through Q2, and into ground, thus swapping the electrodes at both ends of the load. In other words, by controlling the switching combination of the MOSFETs, the power supply polarity at both ends of the load can be adjusted as needed. When the load is a TEC chip, changing the power supply polarity at both ends of the TEC will swap the cold and hot sides of the TEC chip, thereby switching between cooling and heating modes.

[0035] In this embodiment of the invention, a temperature sensor is used to detect the temperature at the current temperature detection point. The temperature sensor can be digital or analog; this embodiment of the invention does not impose any limitation on this.

[0036] Next, the principle of the temperature control system will be explained in conjunction with the working principle of the controller.

[0037] like Figure 5 As shown, controller 501 in the temperature control system reads the current temperature detected by temperature sensor 502. Based on the difference between the current temperature and the target temperature, controller 501 automatically controls the voltage polarity applied to TEC 504 by H-bridge 503, adjusting the heating and cooling modes of TEC 504 so that the current temperature detected by temperature sensor 502 gradually approaches the target temperature and eventually maintains it at the target temperature value. For example, when the current temperature is lower than the target temperature, H-bridge 503 is controlled to put TEC 504 in heating mode. Conversely, when the current temperature is higher than the target temperature, H-bridge 503 is controlled to put TEC 504 in cooling mode. For a description of RC filter 505 and power module 506, please refer to the foregoing embodiment section; this specification will not repeat it here.

[0038] The entire temperature control algorithm can employ a PID control algorithm, adjusting the proportional, integral, and derivative terms respectively to control the system's heating or cooling rate and temperature fluctuations. This embodiment of the invention does not provide a detailed explanation of the specific principles of the PID control algorithm.

[0039] All features disclosed in this specification, or steps in all methods or processes disclosed herein, may be combined in any way, except for mutually exclusive features and / or steps.

[0040] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features for a similar purpose, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0041] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A temperature control system, characterized in that, The system includes: a controller, a power supply polarity switching module, an RC filter circuit, a power supply module, a cooling device, and a temperature sensor; The controller is used to output a power regulation signal; The RC filter circuit is connected to the controller; the RC filter circuit is used to convert the power regulation signal into a DC level and input it to the power supply module; the DC level is used to control the output voltage of the power supply module. The electrode polarity switching module is connected to the controller and the cooling device respectively. The controller is also used to switch the electrode polarity of the cooling device through the electrode polarity switching module based on the current temperature detected by the temperature sensor, so as to control the working mode of the cooling device to be either cooling mode or heating mode.

2. The system as described in claim 1, characterized in that, The cooling device is a semiconductor refrigeration chip (TEC).

3. The system as described in claim 1, characterized in that, The controller is used to control the power regulation signal to maintain its current state after the current temperature detected by the temperature sensor reaches the target temperature, so as to keep the output voltage value of the power module constant.

4. The system as described in claim 1, characterized in that, The power adjustment signal is a pulse width modulation (PWM) signal; the controller is used to control the duty cycle of the PWM signal to adjust the DC level value corresponding to the PWM signal.

5. The system as described in claim 1, characterized in that, The power adjustment signal is a DAC signal; the controller is used to control the level of the DAC signal.

6. The system as described in claim 1, characterized in that, The power module is a BUCK type power supply, a BOOST type power supply, or a BUCK-BOOST type power supply.

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