A method for suppressing surge in PTC heater

Abstract

The present invention relates to the technical field of PTC heaters, and specifically to a method for suppressing rush current of a PTC heater, comprising the following steps: preparing N groups of ceramic sheet groups, each group of ceramic sheet groups including a plurality of PTC ceramic sheets with the same resistance value, and the resistance difference between each two groups of ceramic sheet groups with similar resistance values ​​is k; selecting two groups of ceramic sheet groups with different resistance values, and selecting a number of PTC ceramic sheets from the two groups of ceramic sheet groups to make a heating core, repeating the process multiple times and selecting at least one group of ceramic sheet groups different each time, and the number of PTC ceramic sheets in each heating core is the same, and performing an I‑t test on each heating core; assembling the prepared multiple heating cores into a heater, and performing an I‑t test on the heater. The present invention utilizes that the smaller the resistance of the PTC ceramic sheet, the shorter the time it takes to reach the rush current; by combining PTC ceramic sheets with different resistance values ​​to replace the original conventional PTC ceramic sheets with the same resistance value, the overall resistance becomes smaller, and it is easier to start at low temperature while suppressing the rush current.

Description

Technical Field

[0001] The invention relates to the technical field of PTC heaters, and in particular to a method for suppressing rush current of a PTC heater. Background Art

[0002] Through experiments, it was found that the It (current-time) curve of the PTC ceramic sheet determines that there will be a large current at the moment of its startup, also known as rush current; when multiple PTC ceramic sheets are assembled in parallel into a PTC heater, this rush current will be correspondingly expanded to multiple times, resulting in a large load on the supporting electrical components when the heater is started.

[0003] The existing solution to reduce the rush current is to increase the resistance of the PTC ceramic sheet. This technology has two disadvantages:

[0004] 1. The PTC heater will be unable to start due to low power in a low temperature environment. The corresponding principle is that the resistance of the PTC ceramic piece increases as the temperature decreases in the low temperature range. According to the formula Power=U2 / R, the temperature decreases and the resistance increases, thereby reducing the output power.

[0005] 2. When the battery voltage is lower than the rated voltage, the PTC heater will be unable to start due to low power. The corresponding principle is Power=U2 / R. When the voltage decreases, the output power decreases even if the resistance remains unchanged. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for suppressing an inrush current of a PTC heater, which can effectively solve the problem of a large inrush current when the PTC heater is started in the prior art.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] The present invention provides a method for suppressing surge of a PTC heater, comprising the following steps:

[0009] S1: Prepare N groups of ceramic sheets, each group of ceramic sheets includes multiple PTC ceramic sheets with the same resistance value, and the resistance difference between every two groups of ceramic sheets with similar resistance values ​​is k, and perform an It test on each group of PTC ceramic sheets;

[0010] S2: Select two groups of ceramic sheets with different resistance values, and select a number of PTC ceramic sheets from the two groups of ceramic sheets to make heating cores, repeat multiple times and select at least one group of ceramic sheets from different groups each time, obtain multiple heating cores, each of which has the same number of PTC ceramic sheets, and perform an It test on each heating core;

[0011] S3: Assemble the multiple heating cores prepared in S2 into a heater, and perform an IT test on the heater.

[0012] Furthermore, the number N of the ceramic sheet groups is at least 2.

[0013] Furthermore, the resistance difference of the PTC ceramic sheets in the heating core is at least ak, where a≥1.

[0014] Furthermore, the heater includes two main electrodes, both of which are connected to wires, the heating core includes an aluminum tube, two electrode sheets are provided in the aluminum tube, and the two electrode sheets are electrically connected to the two main electrodes in a one-to-one correspondence, an insulating film is provided in the aluminum tube, and the insulating film is located between the aluminum tube and the electrode sheet, and the PTC ceramic sheet is located between the two electrode sheets.

[0015] Furthermore, two insulating sheets are provided between the two electrode sheets, and the PTC ceramic sheet is located between the two insulating sheets.

[0016] Furthermore, the heater also includes a heat sink mounted on the outside of the aluminum tube, the heat sink is provided with heat sinks, and the heat sink is provided with an auxiliary cleaning component for cleaning the heat sink.

[0017] Furthermore, the auxiliary cleaning assembly includes two slides slidably mounted on the heat sink, each of the two slides is provided with a plurality of scrapers, the side walls of the scrapers are in full contact with the heat sink, an air box is fixedly mounted on the side wall of the heat sink, a piston disk is slidably mounted in the air box, a return spring is connected between the piston disk and the inner wall of the air box, an air bag is provided on the heat sink, and a first connecting pipe is connected between the air bag and the air box, a wind plate is slidably mounted on the outer wall of the air box, permanent magnets are provided on the wind plate and the piston disk, and the two permanent magnets attract each other.

[0018] Furthermore, an electromagnet is provided on the inner wall of the air box, and when the electromagnet is energized, it attracts the permanent magnet on the piston disc.

[0019] Furthermore, the slide frame is provided with a collecting pipe, and the collecting pipe is provided with a plurality of collecting holes, and the number and positions of the collecting holes correspond one-to-one to the scraper, and a second connecting pipe is connected between the air box and the collecting pipe.

[0020] Furthermore, the scraper side wall is provided with a soft pad, and the scraper is made of glass fiber material.

[0021] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects:

[0022] The present invention utilizes that the smaller the resistance of the PTC ceramic sheet, the shorter the time it takes to reach the rush current; by combining PTC ceramic sheets with different resistance values ​​to replace the original conventional PTC ceramic sheets with the same resistance value, the overall resistance becomes smaller, making it easier to start at low temperatures while suppressing the rush current. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 It is an overall schematic diagram of the present invention;

[0025] Figure 2 It is a structural schematic diagram of the heating core part;

[0026] Figure 3 A schematic diagram of the structure of the auxiliary cleaning component part;

[0027] Figure 4 This is the state diagram of the slide sliding up and down;

[0028] Figure 5 This is a comparison chart between the current rushing and the conventional rushing;

[0029] Figure 6 This is the resistance change diagram of PTC ceramic piece in low temperature range;

[0030] Figure 7 The output current diagram of PTC ceramic chips with different resistance values ​​after power is turned on;

[0031] Figure 8 This is the output current diagram of the heating core made with different PTC ceramic sheet combinations after power is turned on;

[0032] Fig. 9 Output current diagram of heaters made with different resistance heating cores;

[0033] Fig.10 The output current comparison chart of heaters made of heating cores with different resistance values ​​and heating cores with the same resistance value.

[0034] The numbers in the figure represent: 1. main electrode; 2. wire; 3. aluminum tube; 4. heat sink; 5. heat sink; 6. insulating film; 7. PTC ceramic sheet; 8. insulating sheet; 9. electrode sheet; 10. slide; 11. air box; 12. piston disc; 13. return spring; 14. wind plate; 15. air bag; 16. first connecting pipe; 17. scraper. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The present invention will be further described below in conjunction with the embodiments.

[0037] Example: Reference Figure 1-Figure 10 A method for suppressing surge of a PTC heater comprises the following steps:

[0038] S1: Prepare N groups of ceramic sheets, each group of ceramic sheets includes multiple PTC ceramic sheets 7 with the same resistance value, and the resistance difference between every two groups of ceramic sheets with similar resistance values ​​is k, and perform an It test on each group of PTC ceramic sheets 7;

[0039] S2: Select two groups of ceramic sheets with different resistance values, and select a number of PTC ceramic sheets 7 from the two groups of ceramic sheets to make heating cores, repeat multiple times and select at least one group of ceramic sheets from different groups each time, obtain multiple heating cores, each of which has the same number of PTC ceramic sheets 7, and perform IT test on each heating core;

[0040] S3: Assemble the multiple heating cores prepared in S2 into a heater, and perform an IT test on the heater.

[0041] The number N of the ceramic sheet groups is at least 2, and the resistance difference of the PTC ceramic sheets 7 in the heating core is at least ak, where a≥1.

[0042] Taking the 800V 6000W new energy vehicle heater as an example, the impulse current is required to be <30A. There are 7 heating cores in a heater, and each heating core has 9 ceramic sheets.

[0043] According to the existing technology, each ceramic chip resistor must be 74KΩ to meet the requirements; the detailed formula is as follows:

[0044] Rush current = voltage / resistance*voltage coefficient*number of heating cores*number of pieces per core*K

[0045] =800 / 74000*6*7*9*6.8

[0046] ≈28(A)

[0047] The K value in the formula is the 800V ceramic chip coefficient, which is 6.8.

[0048] like Figure 5As shown, the existing rush current suppression method is to increase the resistance of the PTC ceramic sheet to obtain a reduced rush current, but increasing the resistance will reduce the rated voltage, thereby reducing the output power overall.

[0049] For this purpose, improvements were made and a new heating core was made by combining PTC ceramic sheets with different resistance values. While ensuring stable output power, it also has a good rush current suppression effect.

[0050] The details are as follows:

[0051] Assuming N=6 and k=5KΩ in step S1, the 40-70KΩ PTC ceramic sheet 7 is divided into 6 gears according to 5KΩ / gear, wherein the output current of the PTC ceramic sheet 7 with 6 different resistance gears over time is as follows: Figure 7 shown.

[0052] Assuming that the resistance values ​​of the PTC ceramic sheets 7 are: k1, k2, k3, k4, k5, ..., kn (where n is a positive integer), the formula of the heating core made of the PTC ceramic sheets 7 with different resistance values ​​is:

[0053] k1*X1Pcs+k2*Y1Pcs; (where Pcs is the quantity unit of PTC ceramic sheet 7)

[0054] The prepared heating core is called the first heating core, and the heating core after it is called the second heating core, and so on. At least one of the PTC ceramic sheets 7 in the second heating core cannot be the same as the PTC ceramic sheets 7 in the first heating core, that is, the formula of the second heating core is any one of the following three:

[0055] k1*X2Pcs+(not k2)*Y2Pcs;

[0056] k2*X2Pcs+(not k1)*Y2Pcs;

[0057] (non k1)*X2Pcs+(non k2)*Y2Pcs;

[0058] Among them, X1+Y1=X2+Y2;

[0059] In addition, each heating core described above includes two PTC ceramic sheets 7 with different resistance values. According to requirements, three or more PTC ceramic sheets 7 with different resistance values ​​can be provided to form a heating core.

[0060] Make the heating element according to the above recipe:

[0061] Formula I: (65-70KΩ)*5Pcs+(60-65KΩ)*4Pcs to make 3 heating cores;

[0062] Formula II: (55-60KΩ)*5Pcs+(50-55KΩ)*4Pcs to make 2 heating cores;

[0063] Recipe III: (45-50KΩ)*5Pcs+(40-45KΩ)*4Pcs to make 2 heating cores.

[0064] Since each heating core in the above-mentioned new energy vehicle heater is composed of 9 PTC ceramic sheets 7 , the heating core in the above-mentioned formula is also composed of 9 PTC ceramic sheets 7 .

[0065] It test chart under different formulas Figure 8 shown.

[0066] The heating cores prepared by the above three groups of formulas are combined to form Figure 1 The heaters shown can be installed at intervals according to the above quantity to ensure balanced heat dissipation.

[0067] The size of the impulse flow shown by the heater is as follows Fig. 9 As shown, comparing it with the existing heater flow, the following is obtained: Fig.10 Comparison chart shown.

[0068]

[0069] By comparing the data in the above table, it can be seen that by reducing the resistance and using PTC ceramic sheets 7 with different resistance values ​​to configure the heating core, the size of the heater's inrush current can be effectively reduced, and the subsequent output current remains basically unchanged, that is, the output power can be well guaranteed and is very stable.

[0070] Compared with the existing heater, the improved heater has a lower overall resistance, but the power remains unchanged. Since the overall resistance is smaller, it is easier to start under low temperature conditions, which improves the overall stability of the heater.

[0071] refer to Figure 1-Figure 4The heater includes two main electrodes 1, and the two main electrodes 1 are connected with a wire 2. The heating core includes an aluminum tube 3, and two electrode sheets 9 are provided in the aluminum tube 3, and the two electrode sheets 9 are electrically connected to the two main electrodes 1 in a one-to-one correspondence. An insulating film 6 is provided in the aluminum tube 3, and the insulating film 6 is located between the aluminum tube 3 and the electrode sheet 9. A PTC ceramic sheet 7 is located between the two electrode sheets 9. Two insulating sheets 8 are provided between the two electrode sheets 9, and the PTC ceramic sheet 7 is located between the two insulating sheets 8. The heater also includes a heat sink 4 installed on the outside of the aluminum tube 3, and a heat sink 5 is provided in the heat sink 4. The heat sink 4 is provided with an auxiliary cleaning component for cleaning the heat sink 5. The auxiliary cleaning component includes two slides 10 slidably installed on the heat sink 4, and a plurality of scrapers 17 are provided on the two slides 10. The side walls of the scrapers 17 are connected to the heat sink. The sheet 5 is in full contact, an air box 11 is fixedly installed on the side wall of the heat dissipation frame 4, a piston disk 12 is slidably installed in the air box 11, a return spring 13 is connected between the piston disk 12 and the inner wall of the air box 11, an air bag 15 is provided on the heat dissipation frame 4, and a first connecting pipe 16 is connected between the air bag 15 and the air box 11, a wind plate 14 is slidably installed on the outer wall of the air box 11, permanent magnets are provided on the wind plate 14 and the piston disk 12, and the two permanent magnets attract each other, an electromagnet is provided on the inner wall of the air box 11, and the electromagnet is attracted to the permanent magnet on the piston disk 12 when energized, a collecting pipe is provided on the slide 10, and a plurality of collecting holes are provided on the collecting pipe, and the number and position of the collecting holes correspond one by one to the scraper 17, a second connecting pipe is connected between the air box 11 and the collecting pipe, a soft pad is provided on the side wall of the scraper 17, and the scraper 17 is made of glass fiber material.

[0072] The working principle of the heater is mainly to transfer the heat generated by the heating core to the heat sink 4, which is then dissipated to the outside by the heat sink 5 of the heat sink 4. When the airflow passes through the heat sink 5, the heat is taken away to achieve the purpose of blowing hot air. In order to ensure long-term heating efficiency and quality, the heat sink 4 in the heater needs to be cleaned periodically to ensure the quality of its heat conduction.

[0073] Manual cleaning is very inconvenient and has high maintenance costs. Therefore, an auxiliary cleaning component is provided on the heat sink 4. When the heater is working, Figure 3 and Figure 4As shown, there will be airflow to blow the wind plate 14, and the wind plate 14 drives the piston disc 12 to slide for a period of time through magnetic force. During the sliding process, the air pressure in the air box 11 will change. At this time, the air box 11 will extract the air in the air bag 15 to shrink it and pull the scraper 17 to slide. When the work stops, under the elastic force of the reset spring 13, the piston disc 12 and the wind plate 14 slide in the opposite direction, and the air pressure is used again to inflate the air bag 15, and the scraper 17 is driven to slide again, so as to achieve the purpose of secondary cleaning. At this time, another part of the air box 11 will extract the air in the collection pipe, so that the air around the heat sink 5 will enter the collection hole (not shown in the figure) with dust, to assist in collecting dust. It is worth noting that a one-way valve is provided on the second connecting pipe, and a blowing hole is provided on one side of the air box 11.

[0074] The air box 11 is also provided with an electromagnet, which is externally connected to a control switch. The electromagnet can be activated by the external control switch, and the magnetic force replaces the wind force to complete the cleaning process. The service life of the heater is extended, and the heating quality of the heater is also improved.

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing surge in a PTC heater, characterized in that: The following steps are involved: S1: preparing N groups of ceramic sheets, each group of ceramic sheets comprising a plurality of PTC ceramic sheets (7) with the same resistance value, and the resistance difference between every two groups of ceramic sheets with similar resistance values ​​is k, and performing an It test on each group of PTC ceramic sheets (7); S2: selecting two groups of ceramic sheets with different resistance values, and selecting a plurality of PTC ceramic sheets (7) from the two groups of ceramic sheets to make a heating core, repeating the process multiple times and selecting at least one group of ceramic sheets that are different each time, to obtain a plurality of prepared heating cores, each of which has the same number of PTC ceramic sheets (7), and performing an IT test on each heating core; S3: Assemble the multiple heating cores prepared in S2 into a heater, and perform an IT test on the heater.

2. A method for suppressing surge of a PTC heater according to claim 1, characterized in that: The number N of the ceramic sheet groups is at least 2.

3. A method for suppressing surge of a PTC heater according to claim 1, characterized in that: The resistance difference of the PTC ceramic sheets (7) in the heating core is at least ak, where a≥1.

4. A method for suppressing surge of a PTC heater according to claim 1, characterized in that: The heater comprises two main electrodes (1), both of which are connected to a wire (2), the heating core comprises an aluminum tube (3), two electrode sheets (9) are provided in the aluminum tube (3), and the two electrode sheets (9) are electrically connected to the two main electrodes (1) in a one-to-one correspondence, an insulating film (6) is provided in the aluminum tube (3), and the insulating film (6) is located between the aluminum tube (3) and the electrode sheet (9), and the PTC ceramic sheet (7) is located between the two electrode sheets (9).

5. A method for suppressing surge of a PTC heater according to claim 4, characterized in that: Two insulating sheets (8) are provided between the two electrode sheets (9), and the PTC ceramic sheet (7) is located between the two insulating sheets (8).

6. A method for suppressing surge of a PTC heater according to claim 4, characterized in that: The heater further comprises a heat sink (4) mounted on the outside of the aluminum tube (3), a heat sink (5) being provided in the heat sink (4), and an auxiliary cleaning component for cleaning the heat sink (5) being provided on the heat sink (4).

7. A method for suppressing surge of a PTC heater according to claim 6, characterized in that: The auxiliary cleaning assembly comprises two slides (10) slidably mounted on a heat sink (4), the two slides (10) being provided with a plurality of scrapers (17), the side walls of the scrapers (17) being in full contact with the heat sink (5), an air box (11) being fixedly mounted on the side wall of the heat sink (4), a piston disc (12) being slidably mounted in the air box (11), a return spring (13) being connected between the piston disc (12) and the inner wall of the air box (11), an air bag (15) being provided on the heat sink (4), a first connecting pipe (16) being connected between the air bag (15) and the air box (11), an air plate (14) being slidably mounted on the outer wall of the air box (11), the air plate (14) and the piston disc (12) being provided with permanent magnets, and the two permanent magnets attract each other.

8. A method for suppressing surge of a PTC heater according to claim 7, characterized in that: An electromagnet is provided on the inner wall of the air box (11), and when the electromagnet is energized, it attracts the permanent magnet on the piston disc (12).

9. A method for suppressing surge of a PTC heater according to claim 8, characterized in that: The slide frame (10) is provided with a collecting pipe, and the collecting pipe is provided with a plurality of collecting holes, and the number and positions of the collecting holes correspond one to one with the scraper (17), and a second connecting pipe is connected between the air box (11) and the collecting pipe.

10. A method for suppressing surge of a PTC heater according to claim 9, characterized in that: The side wall of the scraper (17) is provided with a soft pad, and the scraper (17) is made of glass fiber material.

Images