KR20210027911A - Water purifier - Google Patents

Abstract

The present invention relates to a water purifier for controlling the temperature of hot water in a water purifier to a desired temperature. According to an embodiment of the present invention, the water purifier includes: a hot water tank storing water; a working coil placed on one side of the hot water tank and formed to heat the water in the hot water tank; a heating module including a plurality of switching elements and applying a voltage and a current to the working coil by performing turn-on/off switching operations of the switching elements in accordance with a switching signal; and a sub control part calculating an average electric power value for a set time based on the voltage and the current and generating and outputting a switching signal for the turn-on/off switching operations of the switching elements to the heating module so as to reduce an electric power error between the calculated average electric power value and an electric power command value received from a main control part.

Description

Water purifier {WATER PURIFIER}

The present invention relates to a water purifier, and in particular, to a water purifier for controlling the temperature of hot water in the water purifier to a desired temperature.

In general, a water purifier is a device that converts into safe and hygienic drinking water by filtering various harmful components harmful to the human body contained in raw water, such as tap water or groundwater, by several stages of filters installed inside the body.

In addition to room temperature water, water purifiers also provide hot and cold water. A water purifier that provides hot and cold water has separate heating devices and cooling devices therein. The heating device is configured to generate hot water by heating the purified water, and the cooling device is configured to cool the purified water to generate cold water.

In order for a water purifier to provide hot or cold water, it must be able to heat or cool the purified water in a short time. There can be several ways in which the heating device heats the purified water in a short time.

For example, Korean Patent Publication No. 10-0817832 discloses a configuration of heating purified water using a planar heating heater. In addition, Korean Patent Publication No. 10-0577239 discloses a configuration for heating purified water using an induction heating method.

Induction heating refers to a method of heating an object to be heated using electromagnetic induction. When current is supplied to the coil, an eddy current is generated in the object to be heated, and Joule heating generated by the resistance of the metal increases the temperature of the object to be heated.

In the induction heating method, a current of a resonant frequency is applied to the coil according to an electric signal using a resonant converter inside, so the temperature of hot water can be adjusted based on an electric signal applied to the induction heating module.

However, since the conventional induction heating method controls the temperature based on the temperature of the hot water, it takes a long time to detect the temperature because the power command value is applied in consideration of the temperature error between the temperature of the hot water to be taken out and the target temperature. There is a problem in that it takes a long time for the temperature of water to reach the target temperature because it is difficult to immediately respond to the temperature demand.

In addition, this induction heating method may control the temperature by changing the resonance frequency of the current flowing through the coil, but there is a problem in that the voltage consumption increases and heat generation occurs when the resonance frequency is changed.

In addition, since the resonant converter can be used only in a specific voltage section, there is a limit to the adjustment of the power command value.

Republic of Korea Patent Publication No. 10-0817832 Republic of Korea Patent Publication No. 10-0577239

An object of the present invention is to solve the problem that it takes a long time to meet the user's required temperature because induction heating is performed based on the temperature of water in a hot water tank in the related art, and an object of the present invention is to provide a water purifier that allows the water temperature to reach the required temperature quickly .

An object of the present invention is to provide a water purifier that allows accurate temperature control by adjusting the temperature of water by using an error between the average value of the voltage output value and the power command value for a set time.

An object of the present invention is to provide a water purifier that can use the output of a resonant converter that can be used only in a specific voltage section in all voltage sections.

An object of the present invention is to provide a water purifier capable of accurate control even when a voltage in a region used in an induction heating method based on an electric signal varies.

An object of the present invention is to provide a water purifier that enables precise temperature control by comparing the power command value and the actual voltage output value using a voltage measured during a unit time, not based on the temperature of hot water, and reflecting the error to the power command value. .

A water purifier according to an embodiment of the present invention includes a hot water tank in which water is stored, a working coil disposed at one side of the hot water tank and configured to heat water in the hot water tank, and a plurality of switching elements. A heating module that applies voltage and current to the working coil by performing a turn-on/off switching operation of the switching device according to a signal, and a power average value for a set time based on the voltage and current, and the calculated The heating module outputs a compensation power command value to reduce a power error between the average power value and the power command value received from the main control unit, and generates a switching signal for the turn-on/off switching operation of the switching device according to the output compensation power command value. It includes a sub-control unit that outputs to.

The sub-control unit includes a power average calculation unit that calculates an amount of power using the voltage and current applied to the working coil and calculates a power average value for a set time using the amount of power, and the power average value and the power received from the main control unit. A first comparison unit that compares a command value and outputs the power error, a first PI control unit that outputs the compensation power command value for reducing the power error output from the first comparison unit through proportional integral control, and the output compensation And a switching control unit for generating a switching signal for turning on/off of the switching device according to a power command value and outputting it to the heating module.

The switching control unit generates the switching signal by adjusting a turn on/off duty of the switching signal to reduce the power error.

The water purifier further includes a temperature sensor for measuring a temperature of water in the hot water tank, and the main control unit outputs a temperature difference by comparing the measured temperature of water measured by the temperature sensor with a target temperature of water requested by the user. And a PI control unit for outputting the power command value to the sub-control unit for reducing a temperature difference output from the first comparison unit through a second comparison unit and a proportional integral control.

In this case, the power average calculation unit may calculate a power average value for 80 to 100 ms.

The hot water tank of the water purifier includes a body to be heated inside which is heated by the working coil, and when a current by a voltage applied to the working coil flows, an eddy current is generated in the body to be heated due to a magnetic field generated in the working coil. Generated, the temperature of the object to be heated is raised.

The water purifier according to the embodiment of the present invention has one or more effects as follows.

First, unlike the prior art, the water purifier according to the present invention does not perform induction heating based on the temperature of hot water, but has an effect that accurate temperature control is possible by comparing the actual output power output value with the power command value and reflecting the error. .

Second, the water purifier according to the present invention has an effect that it can be used in all voltage ranges of a resonant converter that can be used only in a specific voltage range.

Third, the water purifier according to the present invention has the effect that accurate control is possible even when the voltage of the region used in the induction heating method based on the electric signal fluctuates.

Fourth, the water purifier according to the present invention can obtain a constant output voltage irrespective of disturbances such as voltage fluctuations, thereby enabling stable temperature control.

1 is a schematic configuration diagram of a water purifier according to an embodiment of the present invention.
2 is a block diagram of a heating module in the water purifier.
3 is a block diagram of a control unit for explaining a process of controlling the temperature of water in the water purifier.
4 is an exemplary diagram of turn-on/off duty control of a switching device according to a power command value in the water purifier.

Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments make the disclosure of the present invention complete, and are common knowledge in the technical field to which the present invention pertains. It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same elements throughout the specification.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic configuration diagram of a water purifier according to an embodiment of the present invention.

Referring to Figure 1, the water purifier according to the present invention is configured to include a power supply unit 110, a heating module 110, a working coil 130, a hot water tank 140, a temperature sensor 150, and a control unit 180. I can.

The hot water tank 140 may store purified water. When raw water is supplied to the water purifier, it is purified by a pill (not shown), and the purified water is supplied to the hot water tank 140 through an inlet and may be stored in the hot water tank 140.

One side of the hot water tank 140 may be provided with an outlet for transferring the water heated in the hot water tank 140 to a water outlet when a user requests to take out hot water.

A working coil 130 for heating water in the hot water tank 140 may be disposed on the outer surface of the hot water tank 140. The working coil 130 may be installed in contact with the lower or side surface of the hot water tank 140.

A heated object (not shown) heated by the working coil 130 may be disposed inside the hot water tank 140 at a position corresponding to the working coil 130. Such an object to be heated may be made of a magnetic material.

When a current flows through the working coil 130 by the voltage applied to the working coil 130 from the heating module 120, an eddy current is generated in the heated object due to the magnetic field generated in the working coil 130 The temperature can rise.

In this way, water in the hot water tank 140 may be heated according to the temperature increase of the object to be heated.

A temperature sensor 150 for measuring the temperature of water in the hot water tank 140 may be disposed inside the hot water tank 140.

Meanwhile, in another embodiment, the temperature sensor 150 may be arranged to measure the temperature of water discharged from the hot water tank 140 to the outside through a water outlet.

The temperature of water measured by the temperature sensor 150 may be transmitted to the controller 160.

The heating module 120 may convert a voltage supplied from the power supply unit 110 to supply a required voltage to the working coil 130. In this way, the current due to the voltage supplied by the heating module 120 flows through the working coil 130 so that water can be heated by an induction heating method.

One or more switching elements for generating a resonant current may be provided inside the heating module 120. The internal configuration of the heating module 120 will be described later with reference to FIG. 3.

The controller 180 may generate a switching signal for driving the heating module 120. The controller 180 may generate a switching signal so that the heating module 120 operates according to a set operating frequency.

One or more switching elements provided in the heating module 120 may be complementarily turned on and turned off by a switching signal provided by the control unit 160.

The switching device may output a desired voltage and current by performing a switching operation that is turned on/off by the controller 160.

The controller 180 determines the power required for the working coil 130 according to the measurement temperature of water in the hot water tank 140 measured by the temperature sensor 150 disposed inside the hot water tank 140, and accordingly, the heating module By controlling 120, power supplied from the heating module 120 to the working coil 130 may be controlled.

The control unit 180 includes a main control unit 160 for controlling the overall operation of the water purifier, and a sub-control unit 170 for controlling the temperature of water stored in the hot water tank 140 according to a control signal from the main control unit 160. It can be configured.

The main control unit 160 is a power command value required to meet the user's requested water temperature (target temperature) based on the measured temperature of the water in the hot water tank 140 measured by the temperature sensor 150 when a user requests to dispense hot water. May be transferred to the sub-control unit 170.

Specifically, the main control unit 160, when a user requests to take out hot water, the working coil 130 required for the measurement temperature of the water in the hot water tank 140 measured by the temperature sensor 150 to reach the target temperature of water requested by the user. ) And outputs a power command value corresponding to the calculated amount of power to the sub-control unit 170.

In addition, the sub-control unit 170 may control the operation of the heating module 120 to output required voltage and current according to the power command value output from the main control unit 160.

Specifically, the sub-control unit 170 generates a switching signal for controlling the switching operation of the heating module 120 in order to enable the heating module 120 to output power corresponding to the received power command value. ).

Accordingly, the heating module 120 may perform a switching operation according to the switching signal to output power corresponding to the power command value.

The temperature of this water means the temperature that the water to be taken out must have when the user requests the hot water to be dispensed.

On the other hand, the controller 180 can output a switching signal to cause the heating module 120 to operate when the measured temperature of the water inside the hot water tank 140 is less than the target temperature requested by the user. Conversely, the inside of the hot water tank 140 When the measured temperature of the water is higher than the target temperature requested by the user, the switching signal may be prevented from being applied to the heating module 120.

2 is a block diagram of a heating module according to an embodiment of the present invention.

Referring to FIG. 2, the heating module 120 according to the embodiment of the present invention may include a rectifying unit 121, a smoothing unit 122, and an inverter unit 123.

The rectifier 121 may rectify the AC voltage supplied from the power supply 110 to output the rectified voltage.

The rectifier 121 may include a plurality of diodes D1 to D4. In this embodiment, for example, the rectifying unit 121 may be composed of a first diode (D1) and a second diode (D2) connected in series with each other, and a third diode (D3) and a fourth diode (D4) connected in series with each other. have.

The smoothing unit 122 smoothes the voltage rectified by the rectifying unit 121 and outputs a DC voltage. The smoothing unit 122 may include an inductor L1 and a capacitor C1 connected in series with each other.

The inverter unit 123 includes a plurality of switching elements. In an embodiment of the present invention, the inverter unit 123 includes four switching elements, namely, a first switching element (T1), a second switching element (T2), a third switching element (T3), and a fourth switching element (T4). It may include.

The first switching element T1 and the second switching element T2 are connected in series to each other, and may be complementarily turned on and off by switching signals S1 and S2 applied by the control unit 160. Similarly, the third switching element (T3) and the fourth switching element (T4) are connected in series to each other, and can be turned on and off complementarily by the switching signals (S3, S4) applied by the control unit 160. have.

The inverter unit 123 converts the DC voltage provided by the smoothing unit 122 through complementary turn-on and turn-off switching operations of the switching elements T1 to T4 and outputs an AC voltage.

In addition, the inverter unit 123 includes an inductor L2 and a capacitor C2 for converting an AC voltage output by a switching operation of the switching elements T1 to T4 into a resonant current.

The inductor L2 and the capacitor C2 are connected in series with the working coil 130, and the working coil 130 is connected to the working coil 130 through a resonance phenomenon by an AC voltage provided by the switching operation of the switching elements T1 to T4. Resonant current can be supplied.

The working coil 130 may heat the hot water tank 140 placed around the working coil 130 by using a resonance current provided from the inverter unit 108.

When a resonance current is applied to the working coil 130, an eddy current is generated in the object to be heated (not shown) disposed in the hot water tank 140 due to the magnetic field generated in the working coil 130 to increase the temperature of the object to be heated. Then, water stored in the hot water tank 140 may be heated according to an increase in the temperature of the object to be heated.

The sub-control unit 170 generates switching signals S1 to S4 corresponding to each of the switching elements for the switching operation of the switching elements T1, T2, T3, and T4 to provide the respective switching elements T1 to T4. Can be approved.

The operating frequencies of the switching elements T1 to T4 may be determined according to the waveforms of the switching signals S1 to S4.

On the other hand, in the present invention, the sub-control unit 170 performs the switching operation of the switching element provided inside the heating module 120 while the heating operation of heating the water inside the hot water tank 140 by the working coil 130 is performed. The operating frequency for can be kept constant.

3 is a block diagram of a control unit for explaining a temperature control process of water in a water purifier according to an embodiment of the present invention.

Referring to FIG. 3, the control unit 180 of the water purifier according to the embodiment of the present invention may include a main control unit 170 and a sub control unit 160.

The main control unit 170 may be configured to include a second comparison unit 171 and a second PI control unit 172, and the sub-control unit 160 includes a first comparison unit 161, a first PI control unit 162, and It may be configured to include a switching control unit 163 and a power average calculation unit 164.

The main controller 170 may receive the measured temperature of water in the hot water tank 140 from the temperature sensor 150. The measured temperature measured by the temperature sensor 150 may be input to the second comparator 171.

The second comparator 171 may compare the measured temperature with a target temperature of water required by the user and output a temperature difference between the two temperatures.

The temperature difference between the measured temperature and the target temperature may be input to the 2PI control unit 172.

The second PI control unit 172 may output a power command value required to reduce the temperature difference between the target temperature and the measured temperature by performing proportional integral control, and to preferably converge to zero (zero), to the sub-control unit 160. .

Here, the power command value may mean power required for the working coil 130 to eliminate a temperature difference between the measured temperature and the target temperature by reaching the target temperature.

Accordingly, when the target temperature and the measured temperature are input, the main control unit 170 transmits a command value of power required for the working coil 130 to the sub-control unit 160 in order to reduce an error between the two temperatures.

Accordingly, when the power command value is received, the sub-control unit 160 controls the switching elements T1 to T4 of the heating module 120 so that the voltage corresponding to the power command value can be output from the heating module 10 to the working coil 130. Switching signals S1 to S4 for a turn on/off switching operation may be generated and output to the heating module 120.

Specifically, the power command value output from the second PI control unit 172 of the main control unit 170 may be input to the first comparison unit 161 of the sub control unit 160.

The power command value input to the first comparison unit 161 may be output to the switching control unit 163 through the first PI control unit 162.

The switching control unit 162 may generate a switching signal for controlling a switching operation of the switching device so as to output a voltage corresponding to the power command value to the heating module 120 and output it to the heating module 120.

The heating module 120 may supply necessary power to the working coil 130 by performing a switching operation according to the switching signal.

In this case, the power average calculation unit 164 may calculate an average value of power for a set time based on the power supplied from the heating module 120 to the working coil 130.

The power supplied to the working coil 130 may change instantaneously due to various factors such as characteristics of the water purifier or input voltage of a place where the water purifier is installed. However, if the switching operation of the switching device is changed according to the amount of power that changes instantaneously, switching loss may occur in the switching device.

Accordingly, in the embodiment of the present invention, switching loss can be reduced by adjusting the switching operation using the average value of the amount of power for a set time without changing the switching operation of the switching device in accordance with the amount of power that changes every moment.

The calculated power average value may be input to the first comparison unit 161.

Accordingly, the first comparison unit 161 may output a power error by comparing the power command value received from the main control unit 170 with the power average value calculated by the power average calculation unit 164.

The first PI control unit 162 performs a proportional integral control to reduce the power error between the power command value and the power average value, and preferably, the switching control unit 163 to a compensation power command value necessary for the power error to converge to zero. Can be printed as

The compensation power command value is for compensating the power of the corresponding power command value in response to the power error in order to compensate the power command value transmitted from the main control unit 170 so that the power error converges to zero.

In detail, it is to compensate the amount of power so that the average power value during the set time for the power output from the heating module 120 to the working coil 130 approaches the power command value.

The switching control unit 163 may generate a switching signal corresponding to the compensation power command value and output it to the heating module 120.

This switching signal is the switching of the switching element of the heating module 120 in order to output the compensated power amount so that the power average value during the set time becomes close to the power command value with respect to the amount of power output from the heating module 120 to the working coil 130. It becomes a signal.

Accordingly, the heating module 120 may supply power corresponding to the compensated amount of power to the working coil 130 by switching internal switching elements in response to the switching signal.

Meanwhile, the range of power output from the heating module 120 to the working coil 130 may be large according to a temperature difference between the measured temperature of water measured by the current temperature sensor 150 and the target temperature of water requested by the user.

Accordingly, the switching control unit 163 may have a large power error range between the power command value and the power average value according to the range of the power output to the working coil 130. Accordingly, in order to generate the switching signal so that the power error converges to zero, the duty of turning on/off of the plurality of switching elements in the heating module 120 may be adjusted.

By adjusting the turn-on/off duty ratio of the switching elements in this way, it is possible to control the power output from the heating module 120 to the working coil 130 in a wide range.

For example, if the power command value is 1000W and the power average value during the set time is 800W, the power error is 200W during the set time, and to compensate for this, the switching control unit 162 may adjust the turn-on/off duty of the switching device. In this case, the duty can be increased.

Conversely, if the power command value is 1000W and the power average value during the set time is 1200W, the power error during the set time is -200W, and to compensate for this, the switching control unit 162 may adjust the turn on/off duty of the switching device. This can reduce the diesel duty.

Meanwhile, in the prior art, while supplying a voltage corresponding to the power command value to the working coil, the power command value for the working coil is compensated according to the measured temperature of water fed back from the temperature sensor, but in the embodiment of the present invention, the measured temperature and the target temperature Since power is supplied to the working coil according to the power command value corresponding to the error between the two and the power command value is compensated by reflecting the average value of the output power, the compensation speed is faster than the conventional power command value compensation based on the measured temperature, so the temperature control of water is fast. There is this.

In this embodiment, the power average calculation unit 164 may calculate an average value of the amount of power supplied from the heating module 120 to the working coil 130 for a set time of 80 to 100 ms, for example. However, the present invention is not limited to the exemplary setting time, and the setting time may be changed according to the condition of the water purifier.

In this embodiment, when the heating module 120 includes a rectifying unit 121, a smoothing unit 122 and an inverter unit 123 as shown in FIG. 3 in an induction heating type water purifier, one inverter unit 123 In the case of outputting the voltage and current through the turn-on/off switching operation of the switching device, the average value of the output power can be obtained for preferably 90 ms.

Particularly, in the present embodiment, voltage control over the entire range of the output can be performed in the resonant converter whose tuning has been completed so that it can be used only in a specific voltage section through adjustment of the turn-on/off duty of the switching device.

Accordingly, even if a voltage input to the water purifier varies due to a change in the commercial power supply in a region where the water purifier is used, a desired voltage can be supplied by adjusting the turn-on/off duty of the switching elements according to the voltage change.

4 is an exemplary diagram of turn-on/off duty control of a switching device according to a compensation power command value in a water purifier according to an embodiment of the present invention.

4, in the water purifier according to the embodiment of the present invention, the switching control unit 163 of the sub-control unit 160 generates a switching signal corresponding to the compensation power command value according to the power error between the power command value and the power average value, and the heating module It can be printed as (120). In this case, the switching signal may include a turn-on/off duty control signal of a plurality of switching devices.

In one example of the drawing, the turn-on/off duty of the switching device according to the switching operation of the switching device for 90 ms is shown.

(a) shows an example in which the switching device is continuously turned on for 90 ms when the compensation power command value is 2000W. In (b), when the compensation power command value becomes 1600W in the example of (a), a constant turn-off period exists by adjusting the turn-on/off duty of the switching device for 90 ms. At this time, in order to generate the power amount of 1600W, the duty may be 0.8 by turning on 80% and turning off 20%.

(c) is half of 2000W for 90ms when the power command value is 1000W, so the duty can be set to 0.5. Accordingly, the turn-on period and the turn-off period may be halved. In the same principle, (d) allows the turn-on/off switching by adjusting the turn-on/off duty to 0.3 for 90ms when the power command value is 600W.

By adjusting the turn-on/off duty of the switching device as described above, the amount of power corresponding to the compensation power command value can be output to the working coil 130.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, but may be manufactured in various different forms, and those having ordinary knowledge in the technical field to which the present invention pertains. It will be understood that the present invention can be implemented in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are illustrative and non-limiting in all respects.

110: power supply 120: heating module
130: working coil 140: hot water tank
150: temperature sensor 160: sub-control unit
161: first comparison unit 162: second PI control unit
163: switching control unit 164: power average calculation unit
170: main control unit 171: second comparison unit
172: 2nd PI control unit

Claims (6)

A hot water tank in which water is stored;
A working coil disposed on one side of the hot water tank and configured to heat water in the hot water tank;
A heating module that includes a plurality of switching elements and applies voltage and current to the working coil by performing a turn-on/off switching operation of the switching element according to a switching signal;
Based on the voltage and current, calculate a power average value for a set time, output a compensation power command value for reducing a power error between the calculated power average value and a power command value received from the main control unit, and output the compensation power command value according to the outputted compensation power command value. A water purifier comprising a sub-control unit that generates a switching signal for a turn-on/off switching operation of a switching device and outputs it to the heating module. The method of claim 1,
The sub-control unit,
A power average calculation unit that calculates an amount of power using the voltage and current applied to the working coil and calculates a power average value for a set time using the amount of power;
A first comparison unit for comparing the calculated power average value with a power command value received from the main control unit and outputting the power error;
A first PI control unit outputting the compensation power command value for reducing a power error output from the first comparison unit through proportional integral control;
A water purifier comprising a switching control unit for generating a switching signal for turning on/off of the switching device according to the output compensation power command value and outputting it to the heating module. The method of claim 2,
The switching control unit,
A water purifier for generating the switching signal by adjusting a duty of turning on/off of the switching signal to output power corresponding to the compensation power command value from the heating module to the working coil. The method of claim 2,
Further comprising a temperature sensor for measuring the temperature of the water in the hot water tank,
The main control unit,
A second comparison unit comparing the measurement temperature of water measured by the temperature sensor with a target temperature of water requested by the user and outputting a temperature difference;
A water purifier comprising a second PI control unit for outputting the power command value to the sub control unit for reducing a temperature difference output from the second comparison unit through proportional integral control. The method of claim 2,
The power average calculation unit is a water purifier that calculates a power average value for 80 ~ 100ms. The method of claim 1,
The hot water tank includes a body to be heated inside which is heated by the working coil, and when a current by a voltage applied to the working coil flows, an eddy current is generated in the body to be heated due to a magnetic field generated in the working coil. A water purifier in which the temperature of the heating target is increased.

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