Temperature sensor for high-power converter

Abstract

The utility model discloses a temperature sensor for a high-power converter. The temperature sensor comprises a thermistor, a plastic base and a metal sleeve. Wherein the thermistor is a two-terminal device comprising a thermosensitive probe and a lead. And the plastic base is provided with double holes through which leads of the thermistor can penetrate and an annular groove for increasing the creepage distance. The metal sleeve is bonded with the plastic base, the thermosensitive probe is arranged on one side of the annular groove, the annular groove of the plastic base and the metal sleeve are filled with high-thermal-conductivity epoxy glue, and the thermosensitive probe is completely wrapped. A test result shows that the temperature sensor can reach 5kV AC-level withstand voltage at the frequency of 50HZ; and the temperature difference of the test points is less than 3 DEG C. The utility model has the advantages of high pressure resistance, high heat conductivity coefficient, simple manufacture and the like, and is suitable for high-power converter surface temperature monitoring. Meanwhile, a cold and hot impact test result also shows that the temperature sensor can stably operate for a long time in a specific working environment.

Description

Technical Field

[0001] The utility model belongs to the technical field of converters, in particular to a temperature sensor used for a high-power converter. Background Art

[0002] Traditional temperature sensors monitor temperature by directly mounting thermistor probes on the surface of circuit boards. Mounted thermistors cannot withstand high voltages above 2000V. At the same time, the contact area between the thermistor's insulating shell and the circuit board is small, resulting in low heat conduction efficiency and large temperature loss, making it impossible to accurately detect the temperature of the working environment. Utility Model Content

[0003] The purpose of the utility model is to provide a temperature sensor for a high-power converter in response to the problems existing in the above-mentioned prior art, which not only realizes a maximum withstand voltage of 5kVAC at a frequency of 50HZ, but also contacts the circuit board over a large area through a metal sleeve, transfers heat through a high thermal conductivity epoxy adhesive, reduces heat loss, and realizes accurate monitoring of the ambient temperature.

[0004] The technical solution for achieving the purpose of the utility model is: a temperature sensor for a high-power converter, the temperature sensor comprising a thermistor, a plastic base and a metal sleeve, the metal sleeve portion being sleeved on the plastic base, the thermistor being mounted on the plastic base and located in the metal sleeve, the lead of the thermistor extending through the plastic base and then connected to the circuit substrate; the temperature sensor being mounted on the circuit substrate through the metal sleeve.

[0005] Furthermore, the thermistor is a two-terminal device including a thermistor probe and a double lead, wherein the thermistor probe is mounted on the plastic base and is located in the metal sleeve.

[0006] Furthermore, the plastic base is provided with a through hole penetrating the plastic base for the lead wire to pass through.

[0007] Furthermore, the plastic base is provided with an annular groove for increasing the creepage distance.

[0008] Furthermore, the thermistor is mounted on the side of the plastic base where the annular groove is located.

[0009] Furthermore, the annular groove and the metal sleeve are filled with epoxy glue.

[0010] Furthermore, the metal sleeve includes a sleeve portion for placing the thermistor, and an extension piece for mounting the temperature sensor on a circuit substrate.

[0011] Furthermore, the temperature sensor is riveted to the circuit substrate through a riveting hole on the extension piece.

[0012] Furthermore, the plastic base is made of any one or more of PE, PET, PEN and PP.

[0013] Furthermore, the plastic base and the metal sleeve are bonded by epoxy glue.

[0014] Compared with the prior art, the utility model has the following significant advantages:

[0015] (1) The temperature sensor is riveted to the circuit board using bolts, which has higher reliability.

[0016] (2) The annular groove on the plastic base increases the creepage distance and increases the voltage resistance.

[0017] (3) Using metal sleeves and high thermal conductivity epoxy glue, heat loss is reduced, thermal conductivity is better, and temperature monitoring is more accurate.

[0018] The utility model is described in further detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. 4 is a schematic diagram of a cross-sectional structure of a temperature sensor for a high-power converter in an embodiment.

[0020] Figure 2 FIG. 1 is a schematic diagram of the structure of a high-power converter temperature sensor in an embodiment.

[0021] Figure 3 FIG. 1 is a schematic diagram of a creepage distance of a high-power converter in an embodiment, wherein Figure 3 (a) is a schematic diagram of the creepage distance with an annular groove; Figure 3 (b) in the figure shows the creepage distance without the annular groove. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In one embodiment, in combination Figures 1 to 3 , provides a temperature sensor for a high-power converter, the temperature sensor comprising a thermistor 1, a plastic base 2 and a metal sleeve 3, the metal sleeve 3 is partially sleeved on the plastic base 2, the thermistor 1 is mounted on the plastic base 2 and is located in the metal sleeve 3, the lead of the thermistor 1 passes through the plastic base 2 and then extends out to be connected with the circuit substrate circuit, by measuring the change in resistance value, the current operating temperature of the converter can be calculated; the temperature sensor is mounted on the circuit substrate through the metal sleeve 3.

[0025] Preferably, the plastic base 2 and the metal sleeve 3 are bonded together by epoxy glue.

[0026] Furthermore, in one of the embodiments, the thermistor 1 is a two-terminal device including a thermistor probe 1.1 and a double lead 1.2, wherein the thermistor probe 1.1 is mounted on the plastic base 2 and is located in the metal sleeve 3.

[0027] Here preferably, the thermal probe 1.1 is wrapped by an insulating shell.

[0028] Furthermore, in one of the embodiments, the plastic base 2 is provided with a through hole 2.2 penetrating the plastic base 2 for the lead wire to pass through.

[0029] Furthermore, in one of the embodiments, the plastic base 2 is provided with an annular groove 2.1 for increasing the creepage distance.

[0030] Here, preferably, the thermal probe 1.1 is installed on the side of the plastic base 2 where the annular groove 2.1 is located.

[0031] like Figure 3 As shown in (a), the plastic base is designed with an additional annular groove 2.2, and the creepage distance of the high-power temperature sensor is AB+BC+CD+DE+EF; Figure 3 As shown in (b), the plastic base is designed without an annular groove 2.2, and the creepage distance = GH = AB + CD + EF. It can be seen from the comparison that the increased distance = BC + DE, that is, the depth of the groove increases, the creepage distance increases, and the voltage resistance of the temperature sensor increases.

[0032] Here, the bottom width CD of the annular groove 2.2 of the plastic base 2 should take into account the performance of the epoxy glue filled. The smaller the bottom width CD, the higher the risk of the epoxy glue in the annular groove 2.2 of the plastic base 2 being broken down by voltage. The breakdown leads to carbonization to form a conductive path, which reduces the creepage distance and the voltage resistance capability.

[0033] Furthermore, in one of the embodiments, the annular groove 2.1 and the metal sleeve 3 are filled with high thermal conductive epoxy glue.

[0034] Here, the filling of the annular groove 2.2 is to reduce the friction stress between the lead 1.2 of the thermistor 1 and the through hole of the plastic base 2, and to increase the reliability of the lead 1.2 of the thermistor 1. The use of epoxy glue to fill the metal sleeve 3 is not only to increase the heat conduction efficiency, but also to a certain extent to protect the thermal probe 1.1 of the thermistor 1 from mechanical stress such as vibration, thereby increasing the working life of the temperature sensor.

[0035] Here, preferably, the annular groove 2.2 needs to be pre-spattered with glue to avoid subsequent glue filling. The glue has poor fluidity, resulting in the glue being unable to completely fill the annular groove 2.2, forming a bubble cavity. Because the bubble cavity will break down under the action of voltage, the arc during breakdown will cause local carbonization of the epoxy glue, forming a current conduction path, resulting in a reduction in the creepage distance, which reduces the voltage resistance performance of the temperature sensor.

[0036] Preferably, the epoxy adhesive is a high temperature resistant material and a high thermal conductive material with a thermal conductivity of 3W / mK.

[0037] Here, preferably, the epoxy adhesive has a low thermal expansion coefficient to avoid applying internal stress to the thermistor 1 probe within the temperature range, thereby avoiding damage to the thermistor 1 .

[0038] Here, preferably, the filled epoxy glue is cured in a vacuum oven, and the curing temperature is determined according to the material properties. Vacuum curing of epoxy glue can avoid the internal voids formed by the organic solvent of the glue during the curing process, which may cause breakdown under high pressure. After the heat curing, the product should be slowly cooled to room temperature to avoid the material shrinkage stress caused by the sudden drop in temperature acting on the thermistor 1 probe, causing damage to the thermistor 1.

[0039] Furthermore, in one of the embodiments, the metal sleeve 3 includes a sleeve portion 3.1 for placing the thermistor 1, and an extension piece 3.2 for mounting the temperature sensor on a circuit substrate.

[0040] Here, preferably, the metal sleeve 3 contacts the circuit substrate plane with an area as large as possible to increase the heat conduction efficiency.

[0041] Here preferably, the metal sleeve 3 is made of aluminum with high thermal conductivity, which has high thermal conductivity, high heat conduction efficiency and low heat loss. Using the metal sleeve 3 made of aluminum can increase the thermal conductivity of the temperature sensor and improve the accuracy of the temperature sensor.

[0042] Preferably, the temperature sensor is riveted to the circuit substrate through the riveting hole 3.2.1 on the extension piece 3.2, and bolt riveting is adopted here but not limited to.

[0043] Here, preferably, the plastic base 2 is made of any one or more of PE, PET, PEN and PP.

[0044] In summary, the utility model has the advantages of high pressure resistance, high thermal conductivity, and simple production. It is suitable for high-power converter surface temperature detection applications. Through testing, it can reach 5kVAC level at 50HZ frequency. The metal sleeve and the thermistor's thermal probe are filled with high thermal conductivity glue, so that the sensor can accurately and reliably measure the surface temperature in a wide temperature range. The results of the hot and cold shock test also show that the temperature sensor can operate stably for a long time under a specific working environment.

[0045] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, and these changes and improvements fall within the scope of the utility model to be protected.

Claims

1. A temperature sensor for a high power converter, characterized in that: The temperature sensor includes a thermistor, a plastic base and a metal sleeve, wherein the metal sleeve is partially sleeved on the plastic base, the thermistor is mounted on the plastic base and is located in the metal sleeve, and the lead wire of the thermistor passes through the plastic base and then extends out to be connected with the circuit substrate; the temperature sensor is mounted on the circuit substrate through the metal sleeve.

2. The temperature sensor for a high power converter according to claim 1, characterized in that: The thermistor is a two-terminal device including a thermistor probe and a double lead, wherein the thermistor probe is mounted on the plastic base and is located in the metal sleeve.

3. The temperature sensor for a high power converter according to claim 1, characterized in that: The plastic base is provided with a through hole for the lead wire to penetrate through the plastic base.

4. The temperature sensor for a high power converter according to claim 1, characterized in that: An annular groove for increasing the creepage distance is provided on one end of the plastic base located inside the metal sleeve.

5. The temperature sensor for a high power converter according to claim 4, characterized in that: The thermistor is mounted on the plastic base at a side where the annular groove is located.

6. The temperature sensor for a high power converter according to claim 4, characterized in that: The annular groove and the metal sleeve are filled with epoxy glue.

7. The temperature sensor for a high power converter according to claim 1, characterized in that: The metal sleeve includes a sleeve portion for placing the thermistor and an extension piece for mounting the temperature sensor on a circuit substrate.

8. The temperature sensor for a high power converter according to claim 7, characterized in that: The temperature sensor is riveted to the circuit substrate through the riveting hole on the extension piece.

9. The temperature sensor for a high power converter according to claim 1, characterized in that: The plastic base is made of any one or more of PE, PET, PEN and PP.

10. The temperature sensor for a high power converter according to claim 1, characterized in that: The plastic base and the metal sleeve are bonded by epoxy glue.

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