PTC heater device and control method thereof

Abstract

A PTC heater device and a control method thereof are provided. The PTC heater device is characterized by comprising: a PTC heater unit for generating heat by using supplied power; a silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) for performing on / off operations, on the supply of power supplied to the PTC heater unit, according to control signals supplied to the gate; a temperature sensor for sensing the current temperature; and a control unit for applying control signals, including an on signal and an off signal, to the gate of the SiC MOSFET, wherein the control unit compares sensing results of the temperature sensor with a set temperature and changes the frequency of signals composed of the on signal and the off signal according to the comparison result.

Description

PTC heater device and control method thereof

[0001] The present invention relates to a PTC heater device and a control method thereof, and more specifically, to a PTC heater device using a SiC MOSFET and a control method thereof.

[0002] A PTC (Positive Temperature Coefficient) heater is an electric heater that converts electrical energy into thermal energy (heat) using a PTC ceramic heating element.

[0003] Here, the "Positive Temperature Coefficient" refers to the fact that electrical resistance increases as temperature rises, thereby enabling the device to self-regulate its heat output.

[0004] These PTC heaters are widely used in various applications because they have a fast response compared to conventional heating elements that rely on electric resistance and can overheat or cause fires, as well as energy efficiency and enhanced safety.

[0005] To control such a PTC element, a type of transistor that handles the on / off of power and a control unit that applies a control signal to the gate of such a transistor are required.

[0006] However, conventionally, the transistors used in PTC heaters were configured as IGBTs.

[0007] An IGBT is a composite device in which the input has a MOSFET structure and the output has a bipolar structure, and this type of IGBT causes several problems.

[0008] First of all, due to the characteristics of IGBTs, there is a limit to increasing the voltage, and there is also a limit to the IGBT's response characteristics when the frequency is increased.

[0009] As a result, even when generating the same output, the low voltage causes high current consumption, leading to a problem of relatively low efficiency (i.e., energy leaks due to resistive components as high current is supplied). Additionally, while increasing the frequency allows for faster heating and thus improves efficiency, it cannot be raised above the audible frequency range, which leads to the problem of generating additional noise.

[0010] (Prior Art) Korean Registered Patent No. 10-1423149

[0011] The present invention has been devised to solve the aforementioned conventional problems, and its purpose is to provide a PTC heater device and a control method thereof that are structured to enable high voltage and minimize noise generation during the control process.

[0012] To achieve the above objective, the PTC heater device according to the present invention comprises: a PTC heater unit that generates heat by power supplied; a SiC (silicon carbide) MOSFET (metal oxide semiconductor field-effect transistor) that performs an on / off operation with respect to the power supplied to the PTC heater unit according to a control signal supplied to the gate; a temperature sensor that senses the current temperature; and a control unit that applies a control signal including an on signal and an off signal to the gate of the SiC MOSFET, wherein the control unit compares the sensing result of the temperature sensor with a set temperature and changes the signal frequency consisting of an on signal and an off signal according to the comparison result.

[0013] Here, the control unit may apply a control signal of a relatively high frequency to the gate of the SiC MOSFET when it determines that the temperature needs to be raised based on the result of comparing the sensing result of the temperature sensor with the set temperature, and may apply a control signal of a relatively low frequency to the gate of the SiC MOSFET when it determines that the temperature needs to be maintained based on the result of comparing the sensing result of the temperature sensor with the set temperature.

[0014] Here, the control unit can adjust the duty ratio of the on signal and the off signal within S1 according to the difference between the current temperature and the set temperature when the temperature needs to be raised as a result of comparing the current temperature and the set temperature based on the sensing result of the temperature sensor.

[0015] Here, when the temperature needs to be maintained as a result of comparing the current temperature and the set temperature according to the sensing result of the temperature sensor, the control unit can control the S2 signal such that the ON signal is composed of a sub-ON signal and a sub-OFF signal of a sub-frequency greater than the frequency W2 of the S2 signal.

[0016] Here, the above W1 and the above W3 may be above the audible frequency.

[0017] In addition, a control method for a PTC (Positive Temperature Coefficient) heater device comprising a PTC heater unit that generates heat by power supplied to achieve the above-mentioned purpose, and a SiC (Silicon Carbide) MOSFET (Metal Oxide Semiconductor Field Effect Transistor) that performs an on / off operation on the power supplied to the PTC heater unit according to a control signal supplied to the gate, may include the steps of: applying a control signal including an on signal and an off signal to the gate of the SiC MOSFET; and sensing the current temperature, comparing the sensing result with the set temperature, and changing and applying a signal frequency consisting of an on signal and an off signal according to the comparison result.

[0018] Here, when it is determined that the temperature needs to be raised based on the comparison of the temperature sensor's sensing result with the set temperature, a control signal of a relatively high frequency is applied to the gate of the SiC MOSFET, and when it is determined that the temperature needs to be maintained based on the comparison of the temperature sensor's sensing result with the set temperature, a control signal of a relatively low frequency is applied to the gate of the SiC MOSFET.

[0019] Here, the control unit can adjust the duty ratio of the on signal and the off signal within S1 according to the difference between the current temperature and the set temperature when the temperature needs to be raised as a result of comparing the current temperature and the set temperature based on the sensing result of the temperature sensor.

[0020] Here, when the temperature needs to be maintained as a result of comparing the current temperature and the set temperature according to the sensing result of the temperature sensor, the control unit can control the S2 signal such that the ON signal is composed of a sub-ON signal and a sub-OFF signal of a sub-frequency greater than the frequency W2 of the S2 signal.

[0021] Here, the above W1 and the above W3 may be above the audible frequency.

[0022] FIG. 1 is a functional block diagram of a PTC heater device according to one embodiment of the present invention, and

[0023] FIGS. 2 to 4 are drawings showing the form of a control signal controlled by the control unit of the PTC heater device of FIG. 1, and

[0024] FIG. 5 is an overall control flow diagram of a PTC heater device according to one embodiment of the present invention.

[0025] The present invention will be described in detail below with reference to the attached drawings.

[0026] The following embodiments according to the present invention are merely examples to aid in understanding the invention, and the invention is not limited to these embodiments. In particular, the present invention may be composed of a combination of at least one of the individual components, individual functions, or individual steps included in each embodiment.

[0027] In particular, for convenience, some claims in the scope of claims have included alphabets such as '(a)', but these alphabets do not define the order of each step.

[0028] An example of a functional block of a PTC heater device (100) according to one embodiment of the present invention is as shown in FIG. 1.

[0029] As shown in the drawing, it may be configured to include a PTC heater unit (110), a SiC MOSFET (120), a temperature sensor (130), and a control unit (140).

[0030] The actual configuration may further include a voltage supply unit, various filter units, voltage regulators, etc.; however, since these components pertain to known technology, they will be omitted, and the description will focus on the characteristic configuration.

[0031] The PTC heater part (110) generates heat by the supplied power and, as mentioned above, uses a PTC (Positive Temperature Coefficient) material.

[0032] The structure of this PTC heater part (110) is merely a known technology, so a more detailed description is omitted.

[0033] The SiC MOSFET (120) performs an on / off operation for the supply of power (especially current) to the PTC heater section (110) according to a control signal supplied to the gate.

[0034] Here, SiC refers to silicon carbide, which differs in several ways from silicon, the basic material of conventional MOSFETs.

[0035] First of all, there is a high critical breakdown electric field voltage (about 2.8 MV / cm higher than 0.3 MV / cm), which significantly reduces the drain-source 'on-state' resistance (RDS(on)), allowing it to operate at a specified rated voltage in a much thinner layer.

[0036] In addition, it has high thermal conductivity, which supports a higher current density per cross-sectional area.

[0037] Furthermore, it has a wide bandgap (the energy difference (eV) between the top of the valence band and the bottom of the conduction band in semiconductors and insulators), which has the effect of reducing leakage current at high temperatures.

[0038] In particular, SiC-based MOSFETs like this enable operation in high frequency bands (above the audible frequency range) while applying high voltage ranges (600V or higher).

[0039] That is, when using a SiC MOSFET (120), compared to a conventional IGBT, if the voltage is increased to produce the same output, the current consumption can be reduced compared to the existing system, and the operating frequency can be increased above the audible frequency so that no noise is generated, and furthermore, efficiency can be increased by applying frequency variation according to the temperature condition.

[0040] Since the structure of the MOSFET itself is merely a known technology, a more detailed explanation is omitted here.

[0041] The temperature sensor (130) performs the function of detecting the current temperature (i.e., the temperature being heated by the PTC heater, which is compared with the set temperature).

[0042] The control unit (140) applies a control signal including an ON signal and an OFF signal to the gate of the SiC MOSFET (120) to ultimately supply power to or cut off the PTC heater.

[0043] At this time, the control unit (140) can apply a control signal of a PWM type in which an on signal and an off signal are repeated.

[0044] In particular, the control unit (140) can compare the sensing result of the temperature sensor (130) with the set temperature and change the signal frequency consisting of an ON signal and an OFF signal according to the comparison result.

[0045] For example, if the control unit (140) determines that the temperature needs to be raised based on the result of comparing the sensing result of the temperature sensor (130) with the set temperature, it can apply a control signal (S1) of a relatively high frequency (W1) to the gate of the SiC MOSFET (120).

[0046] Additionally, the control unit (140) can apply a control signal (S2) of a relatively low frequency (W2) to the gate of the SiC MOSFET (120) when the temperature needs to be maintained as a result of comparing the sensing result of the temperature sensor (130) with the set temperature.

[0047] Figure 2(a) shows an example of a control signal having the above-described W1, and Figure 2(b) shows an example of a control signal having W2.

[0048] Since period and frequency are inversely related, the period of the signal in Fig. 2(a) is 1 / W1, and the period of the signal in Fig. 2(b) is 1 / W2.

[0049] In particular, the control unit (140) can adjust the duty ratio of the on signal and the off signal within S1 according to the difference between the current temperature and the set temperature when the temperature needs to be raised based on the result of comparing the current temperature and the set temperature according to the sensing result of the temperature sensor (130).

[0050] For example, the control unit (140) can increase the duty cycle of the PWM control signal (e.g., 90%) as shown in FIG. 3(a) when the difference between the current temperature and the set temperature is large, and decrease the duty cycle of the PWM control signal (e.g., 50%) as shown in FIG. 3(b) when the difference between the current temperature and the set temperature is small.

[0051] At this time, the signals in Fig. 3(a) and Fig. 3(b) both have the same frequency W1, but only the duty cycle is different.

[0052] Additionally, the control unit (140) can control the current temperature and the set temperature based on the sensing result of the temperature sensor (130) so that when the temperature needs to be maintained, the ON signal in the S2 signal is composed of a sub-ON signal and a sub-OFF signal of a sub-frequency (W3) which is larger than the frequency W2 of the S2 signal.

[0053] Figure 4 shows a drawing of this.

[0054] That is, Fig. 4(a) shows the same S2 signal as Fig. 2(b) described earlier, and Fig. 4(b) can split the ON signal (ON interval) of the S2 signal into a sub-signal of a higher frequency (W3) (i.e., the sub-ON signal and sub-OFF signal are repeated).

[0055] For example, W1 and W3 may be frequencies of 100KHz or higher, which is far beyond the audible frequency range, and W2 may be a frequency of 10Hz to 20Hz, which is low in magnitude even within the audible frequency range.

[0056] Meanwhile, FIG. 5 shows the overall control flow of a PTC heater device (100) according to one embodiment of the present invention.

[0057] In describing this embodiment, it is assumed that the PTC heater device (100) is used for heating an indoor space.

[0058] Upon request by a user or the like, the PTC heater device (100) applies a PWM control signal of a frequency higher than the audible frequency (e.g., the frequency of W1) to the PTC heater unit (110) (step S1).

[0059] After measuring the indoor temperature using the temperature sensor (130) (step S3), the PTC heater device (100) compares the indoor temperature with the set temperature (i.e., the target temperature set by the user, etc.) (step S5), and if the indoor temperature is not higher than the set temperature, the process of steps S1 to S3 described above is performed.

[0060] If the indoor temperature is higher than the set temperature as a result of comparison, the PTC heater device (100) varies the control frequency to W2, which is lower than W1 (step S7).

[0061] Next, the PTC heater device (100) applies a PWM control signal of a variable W2 frequency to the PTC heater unit (110) (step S9).

[0062] At this time, the PTC heater device (100) can split the ON signal among the PWM control signals of frequency W2 into a sub-PWM signal of frequency W3, which is higher than the audible frequency, and maintain it.

[0063] Meanwhile, the process following the above-described step S5 is repeated until the heating continuation (step S11) is terminated by the user, etc.

[0064] Meanwhile, it goes without saying that the process of carrying out each of the above-described embodiments may be performed by a program or application stored on a predetermined recording medium (e.g., computer-readable). Here, the recording medium includes all types of electronic recording media such as RAM (Random Access Memory), magnetic recording media such as hard disks, and optical recording media such as CDs (Compact Disks).

[0065] At this time, the program stored on the recording medium can be executed on hardware such as a computer or a smartphone to perform each of the embodiments described above. In particular, at least one of the functional blocks of the PTC heater device according to the present invention described above can be implemented by such a program or application.

[0066] Furthermore, the present invention is not limited to the specific embodiments described above, but can be implemented with various modifications and variations within the scope of the essence of the invention. It will be obvious that such modifications and variations are included in the present invention if they fall within the scope of the appended claims.

[0067] As explained above, according to the present invention, compared to control using a conventional IGBT, control is possible with high voltage and low current, thereby increasing energy efficiency, and by using a high frequency, damage caused by noise generated in the audible frequency band can be reduced.

Claims

1. In a PTC heater device, A PTC heater unit that generates heat by supplied power; A SiC (silicon carbide) MOSFET (metal oxide semiconductor field-effect transistor) that performs an on / off operation regarding the supply of power to the PTC heater section according to a control signal supplied to the gate; A temperature sensor that senses the current temperature; It is configured to include a control unit that applies a control signal including an ON signal and an OFF signal to the gate of the above SiC MOSFET, and A PTC heater device characterized by the above-described control unit comparing the sensing result of the temperature sensor with the set temperature and changing the signal frequency consisting of an ON signal and an OFF signal according to the comparison result.

2. In Paragraph 1, A PTC heater device characterized by the above-described control unit applying a control signal (S1) of a relatively high frequency (W1) to the gate of the SiC MOSFET when it determines that the temperature needs to be raised based on a comparison of the sensing result of the temperature sensor with the set temperature, and applying a control signal (S2) of a relatively low frequency (W2) to the gate of the SiC MOSFET when it determines that the temperature needs to be maintained based on a comparison of the sensing result of the temperature sensor with the set temperature.

3. In Paragraph 2, A PTC heater device characterized by the above-described control unit adjusting the duty ratio of the on signal and the off signal within S1 according to the difference between the current temperature and the set temperature when the temperature needs to be raised as a result of comparing the current temperature and the set temperature based on the sensing result of the temperature sensor.

4. In Paragraph 2, A PTC heater device characterized by the above-described control unit controlling the on signal in the S2 signal to be composed of a sub-on signal and a sub-off signal of a sub-frequency (W3) which is greater than the frequency W2 of the S2 signal when the temperature needs to be maintained as a result of comparing the current temperature and the set temperature according to the sensing result of the temperature sensor.

5. In Paragraph 4, A PTC heater device characterized in that the above W1 and the above W3 are above an audible frequency.

6. A method for controlling a PTC (Positive Temperature Coefficient) heater device comprising a PTC heater unit that generates heat by supplied power, and a SiC (Silicon Carbide) MOSFET (Metal Oxide Semiconductor Field Effect Transistor) that performs an on / off operation with respect to the supply of power to the PTC heater unit according to a control signal supplied to a gate, (a) a step of applying a control signal including an ON signal and an OFF signal to the gate of the SiC MOSFET; and (b) A method for controlling a PTC heater device characterized by including the step of sensing the current temperature, comparing the sensing result with the set temperature, and changing and applying a signal frequency consisting of an ON signal and an OFF signal according to the comparison result.

7. In Paragraph 6, A control method for a PTC heater device, characterized in that in step (b) above, when it is determined that the temperature needs to be raised based on a comparison of the temperature sensor's sensing result with the set temperature, a control signal (S1) of a relatively high frequency (W1) is applied to the gate of the SiC MOSFET, and when it is determined that the temperature needs to be maintained based on a comparison of the temperature sensor's sensing result with the set temperature, a control signal (S2) of a relatively low frequency (W2) is applied to the gate of the SiC MOSFET.

8. In Paragraph 7, A control method for a PTC heater device characterized by the above-described control unit adjusting the duty ratio of an on signal and an off signal within S1 according to the difference between the current temperature and the set temperature when the temperature needs to be raised as a result of comparing the current temperature and the set temperature based on the sensing result of the temperature sensor.

9. In Paragraph 7, A control method for a PTC heater device, characterized in that the above control unit controls the S2 signal such that when the temperature needs to be maintained as a result of comparing the current temperature and the set temperature according to the sensing result of the temperature sensor, the ON signal is composed of a sub-ON signal and a sub-OFF signal of a sub-frequency (W3) which is larger than the frequency W2 of the S2 signal.

10. In Paragraph 9, A control method for a PTC heater device characterized in that the above W1 and above W3 are above an audible frequency.

11. A computer-readable recording medium having a program for executing the method of any one of paragraphs 6 through 10.

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