KR102612972B1 - Cooling water heater and method for measuring current of cooling water heater - Google Patents

Abstract

A coolant heater and a method for measuring the current of the coolant heater according to an embodiment are disclosed. The coolant heater includes a plurality of heating elements; A plurality of resistors provided in a number smaller than the number of the plurality of heating elements and connected in parallel for at least two heating elements; A switching unit including a plurality of switching elements that apply 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 control unit that generates a plurality of switching signals having the predetermined phase difference, respectively applies them to the plurality of switching elements, and measures current flowing through each of the plurality of resistors at preset sensing time points.

Description

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

The embodiment relates to a coolant heater, and more specifically, to a coolant heater and a method for measuring the current of the coolant heater.

Vehicles driven by engines that use gasoline or diesel as an energy source are currently the most common type of vehicle, but the need for new energy sources for these vehicle energy sources is increasing due to various reasons such as environmental pollution issues and a decrease in oil reserves. As it is increasingly emerging, electric vehicles, hybrid cars, and fuel cell vehicles are currently being commercialized or under development.

Among these, in the case of a vehicle driven by an engine that uses gasoline or gasoline as an energy source, a large amount of heat is generated from the engine. A coolant circulation system is provided to cool the engine, and the heat absorbed from the engine by the coolant is distributed to the interior. It is being used for heating. However, because as much heat as that generated in the engine is not generated in the driving source of electric vehicles, hybrid cars, and fuel cell vehicles, there are limitations in using this conventional method.

Accordingly, various studies are being conducted on electric vehicles, hybrid cars, and fuel cell vehicles, such as adding a heat pump to the 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 these, electric heaters are currently widely used because they can more easily heat coolant without significantly affecting the air conditioning system.

Here, the electric heater includes an air heating type heater that directly heats the air blown into the vehicle's interior, and a coolant heating type heater (or coolant heater) that heats the coolant.

FIG. 1 is a diagram showing the configuration of a coolant heater according to the prior art, and FIG. 2 is a diagram illustrating a PWM control method of a coolant heater according to the prior art.

Referring to Figures 1 and 2, a coolant heater according to the prior art includes a plurality of heating elements 10 that generate heat through electric power and is configured to respectively apply or block current to 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 can be generated. If there are four heating elements, the switching signals, that is, PWM1, PWM2, PWM3, and PWM4, have phase differences of 0˚, 90˚, 180˚, and 270˚.

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

However, since a shunt resistor must be connected to each of the plurality of heating elements, as the number of heating elements increases, the number of shunt resistors also increases, and as the number of shunt resistors increases, the price and size of the controller also increase.

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

Embodiments may provide a method for measuring a coolant heater and a current of the coolant heater.

A coolant heater according to an embodiment of the present invention includes a plurality of heating elements; A plurality of resistors provided in a number smaller than the number of the plurality of heating elements and connected in parallel for at least two heating elements; A switching unit including a plurality of switching elements that apply 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 it may include a control unit that generates a plurality of switching signals having the predetermined phase difference, applies them to the plurality of switching elements, and measures current flowing through the plurality of resistors at each preset sensing time.

When the number of the plurality of heating elements is N and they are divided into K heating element groups of at least 2 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 a heating element group to which the same resistance is connected.

At least two or more currents having a phase difference of (360˚/N) You can.

The control unit generates a plurality of switching signals having the predetermined phase difference, and there may not be an overlapping area between the plurality of switching signals in the active period.

The control unit generates a plurality of switching signals having the predetermined phase difference, and at least a partial overlapping area may exist between the plurality of switching signals in the active period.

The sensing point may be the midpoint of the duty of the switching signal.

The resistor may be a shunt resistor for measuring current.

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

According to another embodiment of the present invention, a method for measuring the current of a coolant heater including a plurality of heating elements and a plurality of resistors connected in parallel for each of at least two heating elements and a number less than the number of the plurality of heating elements is determined in advance. Generating a plurality of switching signals having a phase difference; applying the generated plurality of switching signals to each of the plurality of switching elements to respectively switch the plurality of switching elements; Applying a current having the same phase difference as the corresponding switching signal to each of the plurality of heating elements according to the switching of the plurality of switching elements to generate heat in the corresponding heating elements; And it may include measuring the current 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 they are divided into K heating element groups of at least 2 units, N switching signals having a phase difference of 360°/N can be generated.

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

In the step of generating heat, at least two or more currents having a phase difference of (360˚/N) The phases may be different.

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

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

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

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

According to the embodiment, since a switching signal with a predetermined phase difference and a current with the same phase difference are applied to the heating elements belonging to the same heating element group, control instability due to current sensing error in the overlap section can be minimized.

1 is a diagram showing the configuration of a coolant heater according to the prior art.
Figure 2 is a diagram for explaining a PWM control method of a coolant heater according to the prior art.
Figure 3 is a diagram showing the configuration of a coolant heater according to an embodiment of the present invention.
FIG. 4 is a diagram showing the 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 the principle of current measurement according to an embodiment of the present invention.
Figure 7 is a diagram showing a method for measuring the current of a coolant 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 attached drawings.

However, the technical idea of the present invention is not limited to some of the described embodiments, but may be implemented in various different forms, and as long as it is within the scope of the technical idea of the present invention, one or more of the components may be optionally used between the embodiments. It can be used by combining and replacing.

In addition, terms (including technical and scientific terms) used in the embodiments of the present invention, unless explicitly specifically defined and described, are generally understood by those skilled in the art to which the present invention pertains. It can be interpreted as meaning, and the meaning of commonly used terms, such as terms defined in a dictionary, can be interpreted by considering the contextual meaning of the related technology.

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

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

Additionally, when describing the components of an embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used.

These terms are only used to distinguish the component from other components, and are not limited to the essence, sequence, or order of the component.

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 that other component, but also is connected to that component. It can also include cases where other components are 'connected', 'combined', or 'connected' due to another component between them.

Additionally, when described as being formed or disposed “above” or “below” each component, “above” or “below” refers not only to cases where two components are in direct contact with each other, but also to one This also includes cases where another component described above is formed or placed between two components. In addition, when expressed as “top (above) or bottom (bottom)”, it can include not only the upward direction but also the downward direction based on one component.

In the embodiment, the N heating elements are divided into heating element groups of at least two units, one shunt resistor is connected to each heating element group, and a plurality of switching signals with a phase difference of 360 degrees/N are generated to generate a plurality of switching signals belonging to the same heating element group. We propose a new method in which a current with the same phase difference as a switching signal with a predetermined phase difference is applied to the heating element.

In an 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 is measured through a resistance at each predetermined sensing time.

Figure 3 is a diagram showing the configuration of a coolant heater according to an embodiment of the present invention.

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

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

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

That is, the switching unit 200 can 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.

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

Referring to FIG. 4, the switching unit 200 according to an embodiment of the present invention may include a plurality of switching elements (S1, S2, S3, and 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, and S4) can each be turned on or off by receiving a PWM switching signal, and when turned on, the current supplied from the power supply unit 300 is supplied to the corresponding heating element 100. It 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) is turned on/off by receiving the PWM switching signal PWM3. turns on/off, and the switching element S4 receives the PWM switching signal PWM4 and turns on/off.

Therefore, the switching elements (S1, S2, S3, S4) can apply a square wave current having the same phase difference as the corresponding PWM switching signal to the heating element 100.

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

These multiple switching elements may each receive a PWM switching signal with a predetermined phase difference from the control unit 400 and be switched according to the PWM switching signal.

The power supply unit 300 may supply DC current to generate heat in 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.

At this time, the control unit 400 may determine the phase difference according to the number of heating elements and generate a plurality of PWM switching signals with the determined phase difference. For example, if the number of heating elements is N, the control unit 400 may determine a value of 360°/N as the 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 with a predetermined phase difference, but there is no overlapping area between the plurality of PWM switching signals in the active section that is high. You can.

Here, the active section refers to a section in which current is supplied to the heating element to heat the coolant. In other words, it means the driving section of the switching signal and 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 a partial overlapping area may exist between the plurality of PWM switching signals in the active period.

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

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

At this time, the resistor 50 may be a shunt resistor for measuring current.

In an embodiment, the heating elements may be divided into heating element groups of at least two units, for example, four heating elements may be grouped into two units into one heating element group, or six heating elements may be grouped into two or three units into one heating element group. Alternatively, the eight heating elements can be divided into two or four heating element groups.

Among these, it may be most efficient to divide the four heating elements into two heating element groups. In other words, as the number of heating elements increases, the phase difference decreases, so the non-overlapping section becomes smaller and the efficiency decreases accordingly. Therefore, hereinafter, the case where the four heating elements are divided into two heating element groups, 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 the embodiment, a plurality of PWM switching signals to be applied to the first heating element group and the second heating element group, respectively, may be generated. Here, there is no overlapping area between the plurality of PWM switching signals in the active period.

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

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

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

As another example, the PWM switching signals PWM3 and PWM4 applied to the two heating elements belonging to the second heating element group may have a phase difference of 180 degrees, thereby generating PWM3 with a phase difference of 90 degrees and PWM4 with a phase difference of 270 degrees.

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

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

In this way, in an embodiment of the present invention, a plurality of switching signals having a phase difference of 360 degrees/N are generated and a current having the same phase difference as the switching signal having a phase difference of 180 degrees is attempted to be applied to heating elements belonging to the same heating element group.

As another example, a case where six heating elements are divided into two or three heating element groups will be described.

1) When dividing 6 heating elements into 3 heating element groups of 2, since 360/6=60, a switching signal with a phase difference of 60 degrees is generated, but {0, 180}, {60} for each of the 3 heating element groups. , 240}, generates a switching signal with 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 dividing the 6 heating elements into 2 heating element groups of 3, since 360/6=60, a switching signal with a phase difference of 60 degrees is generated, but for each 2 heating element group, {0, 120, 240}, 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 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 of at least 2 units, a switching signal with a phase difference of 360/N degrees is generated, and the current with 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, but the phases of the currents applied to each heating element may be different.

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

Referring to Figure 6a, when the duty of the PWM switching signal is more than 50%, PWM1 with a 0-degree phase difference, PWM2 with a 90-degree phase difference, PWM3 with a 180-degree phase difference, and PWM4 with a 270-degree phase difference are used by the conventional PWM control method. When applied sequentially, one or two current values can be sampled through two shunt resistors.

In other words, 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 can be accurately measured. It becomes difficult to measure.

In this way, in the case of the conventional PWM control method, two current overlaps occur when the duty of the PWM switching signal is 50%, and there is a possibility of changing the current value at the time the current overlap occurs due to changes 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 Figure 6b, when the PWM switching signal is applied so as to have a phase difference of 180 degrees between the plurality of PWM switching signals 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 if it is more than 50%, one current value can be sampled through two shunt resistors.

In other words, 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 each of the two heating elements in the heating element group can be measured, the current applied to each heating element can be accurately measured. It can be measured.

As such, in the embodiment of the present invention, the current applied to one heating element can always be sampled without current overlap, except when the duty of the PWM signal is 100%.

While the conventional PWM control method causes current overlap at a duty of 50%, the PWM control method according to an embodiment of the present invention causes current overlap at a duty of 100%. 50% duty is used in a wide range of voltages, and 100% duty is more advantageous in terms of control stability because it is required in exceptional situations in a limited voltage range.

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

Figure 7 is a diagram showing a method for measuring the current of a coolant heater according to an embodiment of the present invention.

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

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

Next, the control unit may generate a plurality of PWM switching signals with a determined phase difference (S720).

Next, the control unit may apply the generated plurality of PWM switching signals to the plurality of switching elements of the switching unit to respectively switch the plurality of switching elements (S730).

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

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

At this time, the plurality of heating elements may not generate heat simultaneously but may be sequentially generated by a square wave current having the same phase difference as the PWM switching signal.

Next, the control unit can measure the current through the shunt resistor connected to each heating element.

The term '~unit' used in this embodiment refers to software or hardware components such as FPGA (field-programmable gate array) or ASIC, and the '~unit' performs certain roles. However, '~part' is not limited to software or hardware. The '~ part' may be configured to reside in an addressable storage medium and may be configured to reproduce on one or more processors. Therefore, as an example, '~ part' 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, databases, data structures, tables, arrays, and variables. The functions provided within the components and 'parts' may be combined into a smaller number of components and 'parts' or may be further separated into additional components and 'parts'. Additionally, components and 'parts' may be implemented to regenerate one or more CPUs within a device or a secure multimedia card.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

100: heating element
200: switching unit
300: Power unit
400: Control unit
500: Resistance

Claims (15)

a plurality of heating elements;
A plurality of resistors provided in a number smaller than the number of the plurality of heating elements and connected in parallel for at least two heating elements;
A switching unit including a plurality of switching elements that apply 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 coolant heater comprising a control unit that generates a plurality of switching signals having the predetermined phase difference and applies them to the plurality of switching elements, respectively, and measures current flowing through the plurality of resistors at each preset sensing time. According to paragraph 1,
The control unit,
A coolant heater that generates N switching signals with a phase difference of 360°/N when the number of the plurality of heating elements is N and they are divided into K heating element groups in units of at least 2. According to paragraph 2,
The switching unit,
A coolant heater that applies 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 a heating element group to which the same resistance is connected. According to paragraph 3,
The switching unit,
At least two or more currents having a phase difference of (360˚/N) , coolant heater. According to paragraph 1,
The control unit,
A coolant heater that generates a plurality of switching signals having the predetermined phase difference, and wherein there is no overlapping area between the plurality of switching signals in the active section. According to paragraph 1,
The control unit,
A coolant heater that generates a plurality of switching signals having the predetermined phase difference, and wherein at least a partial overlapping area exists between the plurality of switching signals in an active section. According to claim 5 or 6,
The sensing point is the midpoint of the duty of the switching signal, a coolant heater. According to paragraph 1,
Coolant heater, wherein the resistor is a shunt resistor for measuring current. According to paragraph 1,
A coolant heater wherein the duty of the plurality of switching signals is set to less than 100%. In a method for measuring the current of a coolant heater including a plurality of heating elements, dividing the plurality of heating elements into heating element groups of at least two units, and a plurality of resistors connected in parallel, one for each heating element group,
generating a plurality of switching signals having a predetermined phase difference;
applying the generated plurality of switching signals to each of the plurality of switching elements to respectively switch the plurality of switching elements;
Applying a current having the same phase difference as the corresponding switching signal to each of the plurality of heating elements according to the switching of the plurality of switching elements to generate heat in the corresponding heating elements; and
A method for measuring the current of a coolant heater, comprising measuring the current flowing through each of the plurality of heating elements at each preset sensing time point. According to clause 10,
In the generating step,
When the number of the plurality of heating elements is N and they are divided into K heating element groups in units of at least 2, a method for measuring the current of a coolant heater that generates N switching signals with a phase difference of 360˚/N. According to clause 11,
In the heat generation step,
A method for measuring the current of a coolant heater, which applies 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 a group of heating elements to which the same resistance is connected. According to clause 12,
In the heat generation step,
At least two currents having a phase difference of (360˚/N) × K degrees are applied to each of the K groups of heating elements,
A method for measuring the current of a coolant heater, wherein the phases of at least two currents applied to each of the N heating elements belonging to the K heating element group are different from each other. According to clause 10,
In the generating step,
A method for measuring the current of a coolant heater, generating a plurality of switching signals having the predetermined phase difference, and having no overlapping area between the plurality of switching signals in the active section. According to clause 10,
In the generating step,
A method for measuring the current of a coolant heater, wherein a plurality of switching signals having the predetermined phase difference are generated, and at least a partial overlapping area exists between the plurality of switching signals in an active section.

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