KR20210043091A - Cooling water heater and method for measuring current of cooling water heater - Google Patents

Abstract

According to an embodiment, disclosed are a cooling water heater and a method for measuring a current of the cooling water heater. The cooling water heater comprises: a plurality of heating elements; a plurality of resistors provided in the number less than the number of the plurality of heating elements and connected in parallel for each of at least two heating elements; a switching unit including a plurality of switching elements, which apply a current having the same phase difference as the corresponding switching signal to each of the plurality of heating elements in accordance with a plurality of switching signals having a predetermined phase difference; and a control unit generating the plurality of switching signals having the predetermined phase difference, applying the signals to each of the plurality of switching elements, and measuring a current flowing through the plurality of resistors at every preset sensing time point.

Description

Cooling water heater and method to measure the current of cooling water heater {COOLING WATER HEATER AND METHOD FOR MEASURING CURRENT OF COOLING WATER HEATER}

The embodiment relates to a cooling water heater, and more particularly, to a cooling water heater and a method for measuring the current of the cooling water heater.

Vehicles powered by engines using gasoline and diesel as an energy source are currently the most common types of vehicles, but these vehicle energy sources require a new energy source due to various causes such as reduction in oil reserves as well as environmental pollution. As it is increasingly emerging, electric vehicles, hybrid cars, and fuel cell vehicles are currently being commercialized or under development.

Among them, in the case of a vehicle that uses an engine that uses gasoline as an energy source as an energy source, a lot of heat is generated from the engine, a coolant circulation system is provided to cool the engine, and the heat absorbed from the engine is absorbed indoors. It is supposed to be used for heating. However, since much heat such as that generated by the engine is not generated from the driving sources of electric vehicles, hybrid cars, and fuel cell vehicles, there is a limitation in using such a conventional method.

Accordingly, in electric vehicles, hybrid cars, fuel cell vehicles, etc., various studies have been conducted, such as adding a heat pump to an air conditioning system so that it can be used as a heat source, or providing a separate heat source such as an electric heater. Among them, electric heaters are widely used at present because they can more easily heat cooling water without significantly affecting the air conditioning system.

Here, the electric heater includes an air-heated heater that directly heats air blown into the interior of the vehicle, and a coolant-heated heater (or coolant heater) that heats the coolant.

1 is a view showing the configuration of a cooling water heater according to the prior art, Figure 2 is a view for explaining the PWM control method of the cooling water heater according to the prior art.

1 to 2, the cooling water heater according to the prior art includes a plurality of heating elements 10 that generate heat through power, and is configured to apply or block current to each of the plurality of heating elements according to a PWM switching signal. .

For example, when the number of heating elements is N, N switching signals having a phase difference of 360°/N may be generated. When the number of heating elements is 4, the switching signals, that is, PWM1, PWM2, PWM3, and PWM4 have a phase difference of 0˚, 90˚, 180˚, and 270˚.

At this time, power control of the cooling water heater is performed by connecting a shunt resistor to each of the plurality of heating elements and measuring a current flowing through the connected shunt resistors.

However, since shunt resistors must be connected to each of the plurality of heating elements, if the number of heating elements increases, the number of shunt resistors increases as much, and the price and size of the controller increases as the number of shunt resistors increases.

Unexamined Patent Publication No. 10-2016-0091002 Unexamined Patent Publication No. 10-2015-0098883

The embodiment may provide a cooling water heater and a method for measuring the current of the cooling water heater.

A cooling water heater according to an embodiment of the present invention includes a plurality of heating elements; A plurality of resistors provided in a number less than the number of the plurality of heating elements and connected in parallel to each of at least two heating elements; A switching unit including a plurality of switching elements for applying a current having the same phase difference as the corresponding switching signal to the plurality of heating elements according to a plurality of switching signals having a predetermined phase difference; And a controller configured to generate a plurality of switching signals having the predetermined phase difference, apply each of the plurality of switching signals to the plurality of switching elements, and measure currents flowing through the plurality of resistors at each preset sensing time point.

When the number of the plurality of heating elements is N and divided into K heating element groups in at least two units, the control unit may generate N switching signals having a phase difference of 360°/N.

The switching unit may apply a current having the same phase difference as a switching signal having a phase difference of (360°/N)×K degrees to at least two heating elements belonging to the heating element group to which the same resistance is connected.

At least two currents having a phase difference of (360˚/N)×K degrees are applied to the K heating element groups, but the phases of at least two or more currents respectively applied to the N heating elements belonging to the K heating element groups are different from each other. I can.

The control unit may generate a plurality of switching signals having the predetermined phase difference, and regions overlapping each other in an active period may not exist between the plurality of switching signals.

The control unit may generate a plurality of switching signals having the predetermined phase difference, and a region overlapping at least in part in an active period may exist between the plurality of switching signals.

The sensing timing may be an intermediate point of the duty of the switching signal.

The resistance may be a shunt resistor for measuring current.

The duty of the plurality of switching signals may be set to less than 100%.

A method for measuring the current of a cooling water heater including a plurality of heating elements and a plurality of resistors connected in parallel for each of at least two heating elements is provided in a smaller number than the number of the plurality of heating elements and the plurality of heating elements according to another embodiment of the present invention. Generating a plurality of switching signals having a phase difference; Switching the plurality of switching elements by respectively applying the generated switching signals to a plurality of switching elements; Applying a current having the same phase difference as the switching signal to each of the plurality of heating elements according to the switching of the plurality of switching elements to generate heat for the corresponding heating elements; And measuring currents flowing through each of the plurality of heating elements at each preset sensing time point.

In the generating step, when the number of the plurality of heating elements is N and divided into K heating element groups in at least two units, N switching signals having a phase difference of 360°/N may be generated.

In the heating step, a current having the same phase difference as a switching signal having a phase difference of (360°/N)×K may be applied to at least two heating elements belonging to the heating element group to which the same resistance is connected.

In the heating step, at least two currents each having a phase difference of (360°/N)×K degrees are applied to the K heating element groups, and at least two currents applied to each of the N heating elements belonging to the K heating element groups May have different phases.

In the generating step, a plurality of switching signals having the predetermined phase difference may be generated, and regions overlapping each other in an active period may not exist between the plurality of switching signals.

In the generating step, a plurality of switching signals having the predetermined phase difference may be generated, and a region overlapping at least partially in an active period may exist between the plurality of switching signals.

According to an embodiment, since a plurality of heating elements are divided into heating element groups in at least two units, and one shunt resistor is connected for each heating element group, it may be possible to measure the current flowing through each heating element using a small number of resistances. .

According to the embodiment, since the number of resistors for measuring current can be reduced, not only the cost of the controller can be reduced, but also the size can be reduced.

According to the embodiment, since a switching signal having a predetermined phase difference and a current having the same phase difference are respectively applied to heating elements belonging to the same heating element group, it is possible to minimize control instability due to a current sensing error in the overlapping section.

1 is a view showing the configuration of a cooling water heater according to the prior art.
2 is a view for explaining a PWM control method of the cooling water heater according to the prior art.
3 is a view showing the configuration of a cooling water heater according to an embodiment of the present invention.
4 is a diagram showing a detailed configuration of the switching unit shown in FIG. 1.
5A to 5B are diagrams for explaining the principle of generating a switching signal according to an embodiment of the present invention.
6A to 6B are diagrams for explaining a current measurement principle according to an embodiment of the present invention.
7 is a diagram illustrating a method for measuring a current of a cooling water heater according to an embodiment of the present invention.

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

However, the technical idea of the present invention is not limited to some embodiments to be described, but may be implemented in various different forms, and within the scope of the technical idea of the present invention, one or more of the constituent elements may be selectively selected between the embodiments. It can be combined with and substituted for use.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention are generally understood by those of ordinary skill in the art, unless explicitly defined and described. It can be interpreted as a meaning, and terms generally used, such as terms defined in a dictionary, may be interpreted in consideration of the meaning in the context of the related technology.

In addition, terms used in the embodiments of the present invention are for describing the embodiments and are not intended to limit the present invention.

In the present specification, the singular form may also include the plural form unless specifically stated in the phrase, and when described as “at least one (or more than one) of A and (and) B and C”, it is combined with A, B, and C. It may contain one or more of all possible combinations.

In addition, terms such as first, second, A, B, (a), and (b) may be used in describing the constituent elements of the embodiment of the present invention.

These terms are only for distinguishing the constituent element from other constituent elements, and are not limited to the nature, order, or order of the constituent element by the term.

And, when a component is described as being'connected','coupled' or'connected' to another component, the component is not only directly connected, coupled, or connected to the other component, but also with the component. It may also include the case of being'connected','coupled' or'connected' due to another element between the other elements.

In addition, when it is described as being formed or disposed on the “top (top) or bottom (bottom)” of each component, the top (top) or bottom (bottom) is one as well as when the two components are in direct contact with each other. It also includes the case where the above other component is formed or disposed between the two components. In addition, when expressed as "upper (upper) or lower (lower)", the meaning of not only an upward direction but also a downward direction based on one component may be included.

In an embodiment, N heating elements are divided into heating element groups in at least two units, one shunt resistor is connected to each heating element group, and a plurality of switching signals having a phase difference of 360 degrees/N are generated to belong to the same heating element group. A new scheme is proposed in which a current having the same phase difference as a switching signal having a predetermined phase difference is applied to the heating element.

In the embodiment, when applying a current having the same phase difference as a switching signal having a predetermined phase difference to a heating element belonging to the same heating element group, the current applied to each separate heating element through a resistance at each predetermined sensing time point is measured.

3 is a view showing the configuration of a cooling water heater according to an embodiment of the present invention.

Referring to FIG. 3, a cooling water heater according to an embodiment of the present invention may include a heating element 100, a switching unit 200, a power supply unit 300, a control unit 400, and a resistor 500.

The heating element 100 is composed of a resistance component, and generates heat when current is applied to heat the cooling water. Here, the heating element 100 may be implemented in at least two or more.

The switching unit 200 may be switched to apply or block a DC current to the heating element according to a switching signal. Here, the switching signal may be a PWM switching signal, which is a method of converting the pulse width.

That is, the switching unit 200 may be switched according to the PWM switching signal. In an embodiment, the switching unit 200 may be switched according to a PWM switching signal having a phase difference to apply a DC current in the form of a square wave having a phase difference to the heating element 100.

4 is a diagram showing a detailed configuration of the switching unit shown in FIG. 1.

4, the switching unit 200 according to an embodiment of the present invention may include a plurality of switching elements (S1, S2, S3, S4). One side of each of the plurality of switching elements S1, S2, S3, and S4 may be connected in parallel to the power supply unit 300 and the other side may be connected in series to the plurality of heating elements 100.

The switching elements S1, S2, S3, S4 may be turned on or off by receiving a PWM switching signal, respectively, and when turned on, the current supplied from the power supply unit 300 is transferred to the corresponding heating element 100. Can be approved.

For example, the switching element S1 is turned on/off by receiving the PWM switching signal PWM1, the switching element S2 is turned on/off by receiving the PWM switching signal PWM2, and the switching element S3 receives the PWM switching signal PWM3. Thus, it is turned on/off, and the switching element S4 is turned on/off by receiving the PWM switching signal PWM4.

Accordingly, the switching elements S1, S2, S3, and S4 may apply a square wave type current having the same phase difference as the corresponding PWM switching signal to the heating element 100.

Such switching elements may include, for example, Static Induction Transistor (SIT), Bipolar SIT (B-SIT), Metal-Oxide Semiconductor Field Effect Transistor (MOSFET), Insulated Gate Bipolar Transistor (IGBT), and the like.

Each of the plurality of switching elements may receive a PWM switching signal having a predetermined phase difference from the control unit 400 and may be switched according to the PWM switching signal.

The power supply unit 300 may supply DC current to generate heat for the heating element 100.

The control unit 400 may generate a PWM switching signal for switching the switching unit 200 and apply a plurality of generated PWM switching signals to the switching unit 200.

In this case, the controller 400 may determine a phase difference according to the number of heating elements and generate a plurality of PWM switching signals having the determined phase difference. For example, when the number of heating elements is N, the controller 400 may determine a value of 360°/N as a phase difference and generate N PWM switching signals having the determined phase difference of 360°/N.

As an example, the control unit 400 generates a plurality of PWM switching signals having a predetermined phase difference, but there are no overlapping regions between the plurality of PWM switching signals in an active period that becomes high. I can.

Here, the active section means a section in which current is supplied to the heating element to heat the cooling water. That is, it means the switching signal and the driving section of the heating element.

As another example, the control unit 400 generates a plurality of PWM switching signals having a predetermined phase difference, but at least some overlapping regions may exist between the plurality of PWM switching signals in an active period.

A plurality of resistors 50 may be provided, and may be connected in parallel to at least two heating elements one by one. That is, when a plurality of heating elements are divided into heating element groups in at least two units, one resistor may be connected to each of the divided heating element groups.

For example, if the number of heating elements is 4 and the two heating elements are divided into one heating element group, a total of two heating element groups may be generated, and one resistor may be connected in parallel to two heating elements belonging to each heating element group.

In this case, the resistor 50 may be a shunt resistor for measuring current.

In an embodiment, the heating element may be divided into a heating element group in at least two units, for example, four heating elements are grouped into two units into one heating element group, or six heating elements are divided into two or three units into one heating element group. Eight heating elements can be divided into two or four units into one heating element group.

Of these, it may be most efficient to divide the heating element group into two units of four heating elements. That is, since the phase difference decreases as the number of heating elements increases, the non-overlapping section decreases, thereby reducing the efficiency. Therefore, hereinafter, a case in which the four heating elements are divided into two units of a heating element group, that is, a first heating element group and a second heating element group, will be described as an example.

5A to 5B are diagrams for explaining the principle of generating a switching signal according to an embodiment of the present invention.

Referring to FIG. 5A, in an embodiment, a plurality of PWM switching signals applied to each of the first heating element group and the second heating element group may be generated. Here, there is no overlapping region between the plurality of PWM switching signals in the active period.

In this case, the duty of the plurality of PWM switching signals may be set to 25% or less.

In an embodiment, a PWM switching signal may be generated to have a phase difference of 180 degrees between a plurality of PWM switching signals respectively applied to the first heating element group and the second heating element group.

As an example, the PWM switching signals PWM1 and PWM2 applied to two heating elements belonging to the first heating element group may generate PWM1 having a phase difference of 0 degrees and PWM2 having a phase difference of 180 degrees so as to have a phase difference of 180 degrees.

As another example, PWM switching signals PWM3 and PWM4 applied to two heating elements belonging to the second heating element group may generate a phase difference of 180 degrees, and a PWM3 having a phase difference of 90 degrees and a PWM4 having a phase difference of 270 degrees may be generated.

Referring to FIG. 5B, in an embodiment, a plurality of PWM switching signals applied to each of the first heating element group and the second heating element group may be generated. Here, regions overlapping each other in an active period may exist between the plurality of PWM switching signals.

At this time, the duty of the plurality of PWM switching signals may be set to 50% or more.

As described above, in an embodiment of the present invention, a plurality of switching signals having a phase difference of 360°/N are generated to apply a current having the same phase difference as a switching signal having a phase difference of 180° to a heating element belonging to the same heating element group.

In another embodiment, a case of dividing six heating elements into one heating element group in units of two or three will be described.

1) When 6 heating elements are divided into 3 heating element groups in two units, a switching signal with a phase difference of 60 degrees is generated because 360/6=60, but {0, 180}, {60 for each of the three heating element groups. , 240}, and generating a switching signal having a phase difference of {120, 300}. That is, the switching signal applied to the same heating element group has a phase difference of 180 degrees.

2) When 6 heating elements are divided into 2 heating element groups in units of 3, a switching signal with a phase difference of 60 degrees is generated because 360/6=60, but {0, 120, 240} for each of the 2 heating element groups, A current having the same phase difference as the switching signal having a phase difference of {60, 180, 300} is applied. That is, at least two or more currents applied to the same heating element group have a phase difference of 120 degrees.

In summary, when N heating elements are divided into K heating element groups in at least two units, a switching signal having a phase difference of 360/N is generated, but a current having the same phase difference as the switching signal applied to each heating element group is ( It has a phase difference of 360/N)×K degrees.

At least two currents having a phase difference of (360/N)×K degrees are applied to the heating elements belonging to each heating element group, and the phases of the currents applied to each heating element may be different from each other.

6A to 6B are diagrams for explaining a current measurement principle according to an embodiment of the present invention.

6A, when the duty of the PWM switching signal is 50% or more, PWM1 with a phase difference of 0 degrees, PWM2 with a phase difference of 90 degrees, PWM3 with a phase difference of 180 degrees, and PWM4 with a phase difference of 270 degrees as a conventional PWM control method. When is sequentially applied, one or two current values may be sampled through two shunt resistors.

That is, one PWM switching signal is applied to each heating element during one cycle and current sensing is performed four times. Since the current value applied to both heating elements in the heating element group can be measured, the current applied to each heating element is accurately measured. It becomes difficult to measure.

As described above, in the case of the conventional PWM control method, two currents overlap when the duty of the PWM switching signal is 50%, and there is a possibility that the current value varies at a time when current overlap occurs due to fluctuations in the inductance component of the heating element. Therefore, the control linearity of duty 0 to 100% is weakened, which may cause control instability.

Referring to FIG. 6B, when a PWM switching signal is applied to have a phase difference of 180 degrees between a plurality of PWM switching signals respectively applied to the first heating element group and the second heating element group, as in the embodiment of the present invention, the duty of the PWM switching signal is Even above 50%, one current value can be sampled through two shunt resistors.

That is, one PWM switching signal is applied to each heating element during one cycle and current sensing is performed four times.Because the current value applied to each of the two heating elements in the heating element group can be measured, the current applied to each heating element is accurately measured. Can be measured.

As described above, in an embodiment of the present invention, the current applied to one heating element can be sampled at all times without overlapping currents, except when the duty of the PWM signal is 100%.

In the conventional PWM control method, current overlap occurs at a duty of 50%, whereas in the PWM control method according to an embodiment of the present invention, current overlap occurs at a duty of 100%. A duty of 50% is used in various voltage ranges, and a duty of 100% is an exceptionally necessary situation in a limited voltage range, which is more advantageous in terms of control stability.

Preferably, the duty of the PWM switching signal may be set to less than 100%.

7 is a diagram illustrating a method for measuring a current of a cooling water heater according to an embodiment of the present invention.

Referring to FIG. 7, the control unit according to an embodiment of the present invention may determine the number of heating elements to be controlled and determine a phase difference according to the number of heating elements (S710).

As an example, the controller may determine a phase difference according to the number of heating elements and generate a plurality of PWM switching signals having the determined phase difference.

Next, the controller may generate a plurality of PWM switching signals having the determined phase difference (S720).

Next, the controller may switch the plurality of switching elements by respectively applying the generated plurality of PWM switching signals to the plurality of switching elements of the switching unit (S730).

Next, the control unit may generate heat by applying a current supplied from the power supply unit according to the switching of the plurality of switching elements in the form of a square wave having the same phase difference as the PWM switching signal of the corresponding switching element to each of the plurality of heating elements (S740).

At this time, a current having the same phase difference as a switching signal having a phase difference of 180 degrees is applied to two heating elements belonging to the heating element group to which the same resistance is connected.

In this case, the plurality of heating elements may not generate heat at the same time, but may be sequentially heated by a square wave type current having the same phase difference as the PWM switching signal.

Next, the control unit may measure the current through the shunt resistance connected to each heating element.

The term'~ unit' used in this embodiment refers to software or hardware components such as field-programmable gate array (FPGA) or ASIC, and'~ unit' performs certain roles. However,'~ part' is not limited to software or hardware. The'~ unit' may be configured to be in an addressable storage medium, or may be configured to reproduce one or more processors. Thus, as an example,'~ unit' refers to components such as software components, object-oriented software components, class components, and task components, processes, functions, properties, and procedures. , Subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, database, data structures, tables, arrays, and variables. Components and functions provided in the'~ units' may be combined into a smaller number of elements and'~ units', or may be further separated into additional elements and'~ units'. In addition, components and'~ units' may be implemented to play one or more CPUs in a device or a security multimedia card.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. You will understand that you can do it.

100: heating element
200: switching unit
300: power supply
400: control unit
500: resistance

Claims (15)

A plurality of heating elements;
A plurality of resistors provided in a number less than the number of the plurality of heating elements and connected in parallel to each of at least two heating elements;
A switching unit including a plurality of switching elements for applying a current having the same phase difference as the corresponding switching signal to the plurality of heating elements according to a plurality of switching signals having a predetermined phase difference; And
And a control unit configured to generate a plurality of switching signals having the predetermined phase difference, apply each of the plurality of switching signals to the plurality of switching elements, and measure currents flowing through the plurality of resistors at each preset sensing time point. The method of claim 1,
The control unit,
When the number of the plurality of heating elements is N and divided into K heating element groups in at least two units, the cooling water heater generates N switching signals having a phase difference of 360°/N. The method of claim 2,
The switching unit,
A cooling water heater for applying a current having the same phase difference as a switching signal having a phase difference of (360°/N)×K degrees to at least two heating elements belonging to the heating element group connected with the same resistance. The method of claim 3,
The switching unit,
At least two currents having a phase difference of (360˚/N)×K degrees are applied to the K heating element groups, but the phases of at least two or more currents applied to each of the N heating elements belonging to the K heating element groups are different from each other. , Coolant heater. The method of claim 1,
The control unit,
The cooling water heater, wherein a plurality of switching signals having the predetermined phase difference are generated, and regions overlapping each other in an active period do not exist between the plurality of switching signals. The method of claim 1,
The control unit,
The cooling water heater, wherein a plurality of switching signals having the predetermined phase difference is generated, and a region overlapping at least partially in an active period exists between the plurality of switching signals. The method according to claim 5 or 6,
The sensing time point is an intermediate point of the duty of the switching signal, the coolant heater. The method of claim 1,
The resistance is a shunt resistor for measuring current, the coolant heater. The method of claim 1,
The duty of the plurality of switching signals is set to less than 100%, the coolant heater. In a method for measuring a current of a cooling water heater comprising a plurality of heating elements and a plurality of heating elements divided into heating element groups in at least two units, and a plurality of resistors connected in parallel, one for each of the heating element groups,
Generating a plurality of switching signals having a predetermined phase difference;
Switching the plurality of switching elements by respectively applying the generated switching signals to a plurality of switching elements;
Applying a current having the same phase difference as the switching signal to each of the plurality of heating elements according to the switching of the plurality of switching elements to generate heat for the corresponding heating elements; And
A method for measuring a current of a cooling water heater comprising the step of measuring a current flowing through each of the plurality of heating elements at each preset sensing time point. The method of claim 10,
In the generating step,
When the number of the plurality of heating elements is N and divided into K heating element groups in at least two units, N switching signals having a phase difference of 360°/N are generated, a method for measuring a current of a coolant heater. The method of claim 11,
In the step of generating heat,
A method for measuring a current of a cooling water heater, wherein a current having the same phase difference as a switching signal having a phase difference of (360°/N)×K is applied to at least two heating elements belonging to a heating element group having the same resistance connected thereto. The method of claim 12,
In the step of generating heat,
Applying at least two or more currents each having a phase difference of (360˚/N)×K degrees to the K heating element groups,
A method for measuring a current of a cooling water heater, wherein phases of at least two or more currents applied to each of the N heating elements belonging to the K heating element groups are different from each other. The method of claim 10,
In the generating step,
A method for measuring a current of a coolant heater, wherein a plurality of switching signals having the predetermined phase difference are generated, and regions overlapping each other in an active period do not exist between the plurality of switching signals. The method of claim 10,
In the generating step,
A method for measuring a current of a coolant heater, wherein a plurality of switching signals having the predetermined phase difference are generated, and a region overlapping at least partially in an active period exists between the plurality of switching signals.

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