阅读说明：本技术 一种家电设备的恒温控制装置 (Constant temperature control device of household electrical appliance ) 是由 朱敏 张�杰 郑凌波 于 2021-01-06 设计创作，主要内容包括：本发明公开了一种家电设备的恒温控制装置,其包括恒温控制模块、阻值随水温变化的外部热敏电阻R和反馈模块；所述恒温控制模块分别与电源输出端、所述外部热敏电阻R以及所述反馈模块连接,所述恒温控制模块还包括电源模块,所述电源模块用于提供内部工作电压VDD以及基准信号,所述恒温控制模块内部输出恒定电流Iref至所述外部热敏电阻R,所述外部热敏电阻R随温度变化其阻值,从而改变所述恒温控制模块接入所述外部热敏电阻R上的电压,所述恒温控制模块由此而改变其下拉电流,所述反馈模块根据所述恒温控制模块下拉电流的变化,将电流信号反馈给反激式开关电源芯片来控制改变输出负载电压VOUT。本发明能够线性的变化控制输出端的电压,达到温度恒定。(The invention discloses a constant temperature control device of household electrical appliance equipment, which comprises a constant temperature control module, an external thermistor R with the resistance value changing along with the water temperature and a feedback module; the constant temperature control module is respectively connected with the power output end, the external thermistor R and the feedback module, the constant temperature control module further comprises a power module, the power module is used for providing internal working voltage VDD and reference signals, constant current Iref is output to the external thermistor R in the constant temperature control module, the resistance value of the external thermistor R changes along with the temperature, therefore, the voltage of the constant temperature control module connected to the external thermistor R is changed, the constant temperature control module changes the pull-down current of the constant temperature control module, and the feedback module feeds current signals back to the flyback switching power supply chip to control and change the output load voltage VOUT according to the change of the pull-down current of the constant temperature control module. The invention can linearly change and control the voltage of the output end to achieve constant temperature.)

1. A constant temperature control device of household electrical appliance is characterized by comprising a constant temperature control module, an external thermistor R with resistance value changing along with water temperature and a feedback module; the constant temperature control module is respectively connected with the power output end, the external thermistor R and the feedback module, the constant temperature control module further comprises a power module, the power module is used for providing internal working voltage VDD and reference signals, constant current Iref is output to the external thermistor R in the constant temperature control module, the resistance value of the external thermistor R changes along with the temperature, therefore, the voltage of the constant temperature control module connected to the external thermistor R is changed, the constant temperature control module changes the pull-down current of the constant temperature control module, and the feedback module feeds current signals back to the flyback switching power supply chip to control and change the output load voltage VOUT according to the change of the pull-down current of the constant temperature control module.

2. The thermostatic control device of household electrical appliances according to claim 1, wherein the feedback module is an opto-coupler feedback.

3. The constant temperature control device of claim 1, wherein the constant temperature control module comprises a constant current source Iref, a second capacitor C2, a first amplifier AMP1, a second amplifier AMP2, a buffer BUFF, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first MOS transistor Q1 and a second MOS transistor Q2, the constant current source Iref is respectively connected with one ends of the external thermistor R and the fifth resistor R5, the other end of the fifth resistor R5 is connected with the inverting input end of the first operational amplifier AMP1 and one end of the second capacitor C2, the non-inverting input end of the buffer FF BUFF is connected to the reference signal 1 of the power supply module, one end of the first resistor R1 is connected with the output end of the buffer BUFF and the inverting input end, and the other end of the first amplifier AMP1 is connected with the non-inverting input end of the first amplifier AMP 3942 and one end of the second resistor VREF2, the other end of the second resistor R2 is connected with the drain of the first MOS transistor Q1 and one end of a resistor R3, the gate of the first MOS transistor Q1 is connected with the output end of the first amplifier AMP1, the other end of the third resistor R3 is respectively connected with one end of the fourth resistor R4 and the non-inverting input end of the second amplifier AMP2, the other end of the fourth resistor R4 is connected with the drain of the second MOS transistor Q2 and serves as the output end of the constant temperature control circuit to be connected with an optical coupler, the gate of the second MOS transistor Q2 is connected with the output end of the second amplifier AMP2, and the inverting input end of the second AMP amplifier 2 is connected with the reference signal VREF2 of the power module.

4. The thermostat control device of a household electrical appliance according to claim 3, wherein the source of the first MOS transistor Q1, the source of the second MOS transistor Q2, the other end of the external thermistor R and the other end of the second capacitor C2 are all grounded.

5. The thermostat control device of a household electrical appliance according to claim 3, wherein the fifth resistor R5 and the second capacitor C2 form an RC filter circuit.

6. The thermostat control device of an electric home appliance according to claim 5, wherein the VREF1 value is set to a VNTC voltage value corresponding to a constant temperature, and the VNTC value varies with temperature and fluctuates around the VREF1 voltage value.

7. The thermostat control device of a household electrical appliance according to claim 1, wherein the external thermistor R is a negative temperature coefficient resistor.

8. The thermostat control device of a household electrical appliance according to claim 1, wherein the external thermistor R is a positive temperature coefficient resistor, and the external thermistor R and the constant current source Iref exchange positions at this time.

9. The thermostat control device of a home electric appliance according to claim 5, wherein a resistor is connected in series or in parallel to the external thermistor R to change a constant temperature point.

10. The thermostat control device of a household electrical appliance according to claim 5, wherein when the VNTC value is lower than a lower limit value, the FBO outputs a maximum voltage; when the VNTC value is higher than the upper limit value, the FBO outputs a minimum voltage.

Technical Field

The invention relates to the technical field of automatic control, in particular to a constant temperature control device of household electrical appliances.

Background

More and more constant temperature designs of household appliances begin to adopt a semiconductor refrigeration technology, the development of the semiconductor refrigeration technology provides more choices for places without refrigerant pollution, and a semiconductor refrigeration piece is a core element of the semiconductor refrigeration piece and can be applied to places with limited space, high reliability requirements and no refrigerant pollution. The refrigerating ice liner of the water dispenser uses a semiconductor refrigerating technology and is usually matched with a thermistor when in use.

However, when the water dispenser works, two modes, namely a refrigerating mode and a non-refrigerating mode, are usually provided, the water dispenser enters the non-refrigerating mode when the temperature of the water dispenser is lower than a set value, the water dispenser enters the refrigerating mode when the temperature of the water dispenser is higher than the set value, frequent mode jumps can cause the temperature of water to be suddenly cooled and suddenly heated instead of being stabilized at a proper temperature, and more energy is consumed.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a constant temperature control device of household electrical appliance, which can linearly change and control output voltage to make the temperature of the appliance constant.

The invention is realized by the following technical scheme:

a constant temperature control device of household electrical appliance comprises a constant temperature control module, an external thermistor R with resistance value changing along with water temperature and a feedback module; the constant temperature control module is respectively connected with the power output end, the external thermistor R and the feedback module, the constant temperature control module further comprises a power module, the power module is used for providing internal working voltage VDD and reference signals, constant current Iref is output to the external thermistor R in the constant temperature control module, the resistance value of the external thermistor R changes along with the temperature, therefore, the voltage of the constant temperature control module connected to the external thermistor R is changed, the constant temperature control module changes the pull-down current of the constant temperature control module, and the feedback module feeds current signals back to the flyback switching power supply chip to control and change the output load voltage VOUT according to the change of the pull-down current of the constant temperature control module.

Further, the feedback module is an optocoupler feedback.

Further, the constant temperature control module includes the constant current source Iref, a second capacitor C2, a first amplifier AMP1, a second amplifier AMP2, a buffer BUFF, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first MOS transistor Q1, and a second MOS transistor Q2, the constant current source Iref is connected to one end of the external thermistor R and one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected to the inverting input terminal of the first operational amplifier AMP1 and one end of the second capacitor C2, the non-inverting input terminal of the buffer BUFF is connected to the reference signal VREF1 of the power module, one end of the first resistor R1 is connected to the output terminal and the inverting input terminal of the buffer BUFF, the other end is connected to the non-inverting input terminal of the first amplifier 1 and one end of the second resistor R2, the other end of the second resistor R2 is connected to one end of the first amplifier tube AMP1 and one end of the drain 3 of the MOS transistor Q3, the grid of the first MOS tube Q1 is connected with the output end of the first amplifier AMP1, the other end of the third resistor R3 is respectively connected with one end of the fourth resistor R4 and the non-inverting input end of the second amplifier AMP2, the other end of the fourth resistor R4 is connected with the drain of the second MOS tube Q2 and is connected with an optical coupler as the output end of the constant temperature control circuit, the grid of the second MOS tube Q2 is connected with the output end of the second amplifier AMP2, and the inverting input end of the second amplifier AMP2 is connected with the reference signal VREF2 of the power module.

Further, the source of the first MOS transistor Q1, the source of the second MOS transistor Q2, the other end of the external thermistor R, and the other end of the second capacitor C2 are all grounded.

Further, the fifth resistor R5 and the second capacitor C2 form an RC filter circuit.

Further, the VREF1 value is set to a VNTC voltage value corresponding to a constant temperature, which varies with temperature and fluctuates around the VREF1 voltage value.

Further, the external thermistor R is a negative temperature coefficient resistor.

Further, the external thermistor R is a positive temperature coefficient resistor, and at this time, the external thermistor R and the constant current source Iref exchange positions.

Further, a resistor is connected in series or in parallel to the external thermistor R, thereby changing a constant temperature point.

Further, when the VNTC value is lower than a lower limit value, the FBO outputs a maximum voltage; when the VNT value is higher than the upper limit value, the FBO outputs a minimum voltage.

Compared with the prior art, the invention has the advantages that:

1. through constant temperature control module and outside thermistor R part, constant temperature control module links to each other with outside thermistor R, and outside thermistor R can change self resistance according to the temperature change, because outside thermistor R's electric current is invariable, therefore constant temperature control module makes constant temperature control module judge and adjust constant temperature control module's output pull-down current value according to the different voltages that the different resistances of outside thermistor R produced.

2. Through the optical coupler part, the optical coupler is connected with the output end of the constant temperature control module, so that a pull-down current signal of the constant temperature control module is fed back to the flyback switching power supply chip in time, and the output load voltage of the power supply is linearly adjusted.

Drawings

Fig. 1 is a circuit diagram of a thermostat control device of a household electrical appliance according to an embodiment of the present invention;

fig. 2 is a waveform diagram of some parameters of fig. 1.

The device comprises a power supply module, a constant temperature control module and a constant temperature control module, wherein the constant temperature control module is 1, and the power supply module is 2.

Detailed Description

The following non-limiting detailed description of the present invention is provided in connection with the preferred embodiments and accompanying drawings. In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

Fig. 1 is a constant temperature control device of a household appliance according to an embodiment of the present invention, which may be a household water dispenser, and the constant temperature control device of the present invention is described below by taking the household water dispenser as an example.

The constant temperature control device comprises a constant temperature control module 1, an external thermistor R and a feedback module, wherein the constant temperature control module 1 comprises a power supply module 2, and the power supply module 2 is used for providing an internal working voltage VDD and a reference signal.

The constant temperature control device is connected with a flyback switching power supply, the flyback switching power supply mainly comprises a resistor RCS, a switch K1, a primary winding NP, a secondary winding NS, a diode D1, a first capacitor C1, a feedback module, an input end VIN and an output end VOUT, wherein the feedback module is an optical coupler, the resistor RCS is connected with the switch K1 in series, the diode D1 is connected with the optical coupler in series, the optical coupler is connected with the first capacitor C1 in parallel, the negative end of the optical coupler is connected with the drain electrode of a second MOS (metal oxide semiconductor) tube, the output end VOUT is connected with a semiconductor cold plate, the optical coupler collects the pull-down current in the constant temperature control module 1 and feeds the pull-down current to a flyback switching power supply chip to adjust the output voltage, the effect of linearly controlling the output end VOUT to output proper voltage is achieved, when the pull; when the optical coupler is not pulled down, the output voltage is low, the output voltage needs to be increased through adjustment of the power supply chip, and finally the semiconductor refrigerating piece is linearly controlled through the output voltage to achieve a constant temperature effect.

The thermostatic control module 1 comprises a second capacitor C2, a constant current source Iref, a first amplifier AMP1, a second amplifier AMP2, a buffer BUFF, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first MOS transistor Q1, a second MOS transistor Q2 and a power module 2. The first MOS transistor Q1 and the second MOS transistor Q2 both have a pull-down function only. The power module 2 generates a reference signal VREF1, a reference signal VREF2, and an internal operating voltage VDD, which are all constant values, and the reference signal VREF1, the reference signal VREF2, and the internal operating voltage VDD. The fifth resistor R5 and the second capacitor C2 form an RC filter circuit. The external thermistor R is a negative temperature coefficient resistor, namely, the temperature rises, the resistance value drops, the temperature drops and the resistance value rises, and the external thermistor R can also be a positive temperature coefficient resistor, namely, the temperature rises, the resistance value rises, the temperature drops and the resistance value drops, and at the moment, the external thermistor R and the constant current source Iref exchange positions; one end of the external thermistor R is respectively connected with one end of the fifth resistor R5 and the current source, the other end of the external thermistor R5 is grounded, the other end of the fifth resistor R5 is respectively connected with one end of the second capacitor C2 and the inverted input end of the first amplifier AMP1, and the other end of the second capacitor C2 is grounded. One end of a resistor R1 is connected with a buffer BUFF output end and an inverting input end, a reference signal VREF1 is connected to a non-inverting input end of the buffer BUFF, the other end of a first resistor R1 is connected with a non-inverting input end of a first amplifier AMP1 and one end of a second resistor R2, the other end of a second resistor R2 is connected with a drain electrode of a first MOS tube Q1 and one end of a third resistor R3, a grid electrode of the first MOS tube Q1 is connected with an output end of a first amplifier AMP1, a source electrode of the first MOS tube Q1 is grounded, the other end of the third resistor R3 is connected with one end of a fourth resistor R4 and a non-inverting input end of a second amplifier AMP2, the other end of the fourth resistor R4 is connected with a drain electrode of a second MOS tube Q2 and serves as an output end of a constant temperature control circuit and is connected with one end of an optical coupler, a grid electrode of the second MOS tube Q2 is connected with an output end of the second amplifier AMP2, a source electrode.

The working principle is as follows:

with reference to fig. 1 and 2, the reference VREF1 sets a corresponding VNTC voltage value at a constant temperature, the VNTC voltage value varies with temperature and fluctuates around the VREF1 voltage, and the reference voltage VREF2 value is always greater than the VB voltage value. The thermistor can be an RNTC negative temperature coefficient resistor or a PTC positive temperature coefficient resistor, and the following embodiments take the RNTC negative temperature coefficient resistor as an example:

when the constant temperature control module 1 normally works, according to the working principle of the operational amplifier, the VA voltage is always the voltage VREF1, the VC voltage is always the voltage VREF2, when the temperature rises, the resistance of the external thermistor RNTC decreases, and because the current Iref is a constant current, the voltage of the VNTC gradually decreases, when the VNTC is smaller than the VA, the first amplifier AMP1 drives the first MOS transistor Q1 to turn on, at this time, the first MOS transistor Q1 is in a pull-down state, the feedback loop of the first operational amplifier AMP1 normally works, so the VB voltage can be calculated:

since the VB voltage value is always lower than the VC voltage value, the feedback loop of the second operational amplifier AMP2 works normally, so the FBO voltage value is obtained:

in summary,

the output voltage of the thermostatic control module 1 has an upper limit value and a lower limit value along with the temperature change, so when VB is equal to 0V, that is, the NTC voltage reaches the lower limit value, the FBO maximum value is obtained:

at this time, VNTC voltage value:

when the temperature rises to a certain temperature T1 so that VNTC is VNTC1, the maximum VOUT voltage can be obtained, and the semiconductor refrigerating chip refrigerates at the maximum power; when the temperature rises but does not reach T1, the VOUT voltage rises linearly with the VNTC voltage drop (i.e., temperature rise).

When the temperature decreases, the resistance of the external thermistor RNTC increases, and the current Iref is constant, so the voltage of VNTC gradually increases and is greater than VA until the first MOS transistor Q1 is not pulled down at all. Therefore, the FBO voltage can be calculated from the ratio of VA to VC and the resistors R1, R2, R3 and R4 and controlled to be the FBO minimum, i.e.:

to sum up:

at this time, the corresponding VNTC voltage value can be calculated:

when the temperature is reduced to a certain temperature T2 to make VNTC equal to VNTC2, the minimum VOUT voltage can be obtained, and the semiconductor refrigerating chip refrigerates with the minimum power; when the temperature drops but does not reach T2, the VOUT voltage drops linearly with the VNTC voltage rise (i.e., the temperature drop).

Different linear voltage output ranges can be obtained by adjusting the values of VREF1 and VREF2 and the proportion of R1, R2, R3 and R4, the corresponding curve changes as shown in figure 2, when the temperature-sensing constant-current temperature control circuit is used, the resistor R is installed in a water tank and used for sensing the water temperature, and because the current Iref is constant, when the temperature rises to T1, the output FBO is maximum, the flyback switching power supply chip optically couples to acquire the reduction of the FBO pull-down current, the output of a VOUT end is increased by internal adjustment of the flyback switching power supply chip, when the temperature drops to T2, the output FBO is minimum, the optical coupler in the flyback switching power supply chip acquires the increase of the FBO pull-down current, the output of the VOUT end is increased by internal adjustment of the flyback switching power supply chip, so that the semiconductor cold plate adjusts the working state according to the temperature, and the constant. The system can change the constant temperature point by connecting resistors in series or in parallel on the basis of a thermistor R outside the constant temperature control chip.

When the constant temperature control device is used, the constant temperature control module 1 is connected with the external thermistor R through the constant temperature control module 1 and the external thermistor R, the external thermistor R can change the resistance value of the external thermistor R according to the change of water temperature, and the constant temperature control module 1 outputs different voltage values according to different resistance values of the resistor R; the optical coupler is connected with the output end of the constant temperature control module 1 through a feedback optical coupler part, so that the change of the pull-down current of the constant temperature control module 1 is collected in time; the optical coupler feeds the collected current value back to the flyback switching power supply chip, so that the flyback switching power supply chip linearly controls the change of the output voltage VOUT, the refrigeration effect of the refrigeration semiconductor is changed, the water temperature is constant, and frequent mode jumping cannot be carried out to cause 'sudden cooling and sudden heating' of the water temperature.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.