KR20240139820A - Electric compressor - Google Patents

Abstract

The present invention relates to an electric compressor. More specifically, the electric compressor comprises: a compression unit compressing a refrigerant; a motor unit driving the compression unit; and an inverter unit controlling the motor unit. The inverter unit includes: at least one power semiconductor switch; a fixing member directly or indirectly physically connected to one surface of the power semiconductor switch to fix the power semiconductor switch; and a PCB substrate provided in one surface direction of the power semiconductor switch. The PCB substrate includes at least one non-contact type temperature sensor providing the temperature information of the power semiconductor switch without being in contact with the power semiconductor switch.

Description

Electric compressor {Electric compressor}

The present invention relates to an electric compressor, and more particularly, to an electric compressor including an inverter including an infrared temperature sensor.

The automotive air conditioning system refers to a system that encompasses heating, ventilation, and cooling of a vehicle, and is called climatronic, or intelligent air conditioning. As the name suggests, automotive air conditioning refers to technology that makes the interior environment of a vehicle comfortable. In general, an automotive air conditioning system consists of a condenser, a compressor, an evaporator, a receiver, and an expansion device. The compressor, which is widely used in automotive air conditioning systems, sucks in the refrigerant that has completed evaporation from the evaporator, turns it into a high temperature and high pressure state that is easy to liquefy, and delivers it to the condenser. Compressors that perform this function are divided into reciprocating and rotary types. Rotary compressors include mechanical types that use an engine as a driving source and perform rotation, and electric types that use a motor as a driving source. Electric compressors use a separate motor to drive the compressor, and the rotation speed of the motor is controlled by converting direct current into alternating current by the compressor's inverter.

In addition, while the compressor's inverter requires power semiconductor switch elements to drive the motor at high voltage, the power semiconductor switch elements generate a lot of heat, and as the rated voltage of the vehicle increases, the switching loss of the power semiconductor switch increases, so that under poor heat dissipation conditions (low speed, high load), the temperature of the power semiconductor switch increases rapidly, causing the power semiconductor switch elements to be damaged.

Figure 1 is a side schematic diagram of a conventional inverter.

As shown in Fig. 1, conventionally, a thermistor is used to estimate the temperature based on the change in the internal resistance value as the temperature around the element changes. However, when a thermistor is used, there is a problem in that the power semiconductor switch element is damaged due to exceeding the guaranteed temperature of the power semiconductor switch because the temperature followability is low when the junction temperature of the power semiconductor switch element rapidly increases.

Meanwhile, a technology is known for measuring the temperature of an internal semiconductor chip by installing a temperature sensor inside a power semiconductor switch rather than on a PCB board. In this case, there is a problem that a separate lead wire must be connected to the PCB board.

In addition, when measuring the temperature of the surface of a power semiconductor switch, there may be a problem in that the temperature of the semiconductor chip cannot be measured quickly and accurately due to a time delay caused by the temperature difference and thermal time constant between the temperature of the surface of the power semiconductor switch and the temperature of the semiconductor chip (junction temperature) inside the power semiconductor switch.

Korean Patent Publication No. 10-0963980 (“Electric Compressor Including Inverter”, Publication Date 2010.02.17.)

The present invention has been made to solve the above-mentioned problems, and the purpose of the electric compressor according to the present invention is to provide an electric compressor capable of detecting rapid temperature changes by improving temperature followability by directly measuring the temperature of a power semiconductor switch through an infrared temperature sensor rather than indirectly estimating the temperature with a conventional thermistor temperature sensor.

In order to solve the above-described problems, an electric compressor according to various embodiments of the present invention includes a compression unit for compressing a refrigerant, a motor unit for driving the compression unit, and an inverter unit for controlling the motor unit, wherein the inverter unit includes at least one power semiconductor switch, a fixing member for fixing the power semiconductor switch by being directly or indirectly physically connected to one surface of the power semiconductor switch, and a PCB substrate provided in the direction of one surface of the power semiconductor switch, wherein the PCB substrate does not contact the power semiconductor switch and includes at least one non-contact temperature sensor for providing temperature information of the power semiconductor switch.

In addition, the response speed of the temperature sensor is characterized by being 20 mS or more.

In addition, the temperature information is characterized in that it includes a surface temperature of the power semiconductor switch.

In addition, the temperature sensor is characterized as being an infrared temperature sensor.

In addition, the temperature sensor is characterized in that it is mounted on the surface of the PCB substrate, and is mounted on a surface facing the power semiconductor switch.

In addition, the temperature sensor is characterized in that it is provided at a position corresponding to the position with the highest temperature on the surface of the power semiconductor switch.

In addition, the power semiconductor switch includes at least one semiconductor chip, and the temperature sensor is provided at a position corresponding to the center of an area having the greatest amount of heat generation among the semiconductor chips.

Additionally, the PCB substrate is characterized by including a plurality of temperature sensors per power semiconductor switch.

In addition, the temperature sensor is characterized in that it is installed at a location among the plurality of power semiconductor switches where the heat concentration is expected to be higher than a predetermined standard.

In addition, based on the temperature information, the device further includes a control unit that controls the power semiconductor switch, wherein the control unit calculates the junction temperature of the power semiconductor switch based on the surface temperature sensed by the temperature sensor and a thermal resistance formula of the junction of the power semiconductor switch and the fixing member.

In addition, the control unit is characterized in that it calculates the junction temperature of the power semiconductor switch by multiplying the surface temperature sensed by the temperature sensor by a predetermined constant.

In addition, the control unit is characterized in that it controls the power semiconductor switch to operate only within a predetermined temperature range or lower based on the calculated junction temperature of the power semiconductor switch.

In addition, a heat sink is further included between the power semiconductor switch and the fixing member, the PCB substrate further includes a temperature sensor for measuring the temperature of the heat sink, and the control unit is characterized in that it controls the power semiconductor switch based on the temperature of the heat sink and the temperature of the power semiconductor switch.

According to the electric compressor according to various embodiments of the present invention as described above, there is an effect of preventing damage to the power semiconductor switch element by stopping the switching operation before the element guarantee temperature (175°C) is exceeded due to a rapid temperature rise of the power semiconductor switch under poor heat dissipation conditions (low speed, high load).

In addition, it has the effect of improving product performance by expanding the inverter operating range through accurate temperature measurement of power semiconductor switches.

Figure 1 is a side schematic diagram of a conventional inverter.
Figure 2 is a drawing showing the lower surface of a PCB board included in a conventional inverter.
Figure 3 is a side schematic diagram of an inverter unit according to one embodiment of the present invention.
FIG. 4 is a drawing showing the lower surface of a PCB substrate included in an inverter unit according to one embodiment of the present invention.

In order to explain the present invention, the operational advantages of the present invention, and the purpose achieved by practicing the present invention, preferred embodiments of the present invention will be exemplified and examined with reference thereto.

First, the terminology used in this application is only used to describe specific embodiments, and is not intended to limit the present invention, and the singular expression may include plural expressions unless the context clearly indicates otherwise. Also, in this application, it should be understood that the terms "comprise" or "have" and the like are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

In describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description will be omitted.

Before explaining the present invention, a conventional inverter will be described in more detail with reference to FIGS. 1 and 2.

Figure 1 is a side schematic diagram of a conventional inverter.

Figure 2 is a drawing showing the lower surface of a PCB board included in a conventional inverter.

As shown in FIGS. 1 and 2, a conventional inverter may include a power semiconductor switch (10), an inverter case (20), a PCB substrate (30), a refrigerant (40), and a temperature sensor (50).

A lead wire (11) is formed in the power semiconductor switch (10), and can be connected to the inverter case (20) via a bolt (B). In addition, a heat sink (21) is arranged between the power semiconductor switch (10) and the inverter case (20). A coolant (40) is located at the bottom of the inverter case (20) and serves to cool the heat generated from the power semiconductor switch (10).

Therefore, when looking at the heat transfer path, the heat generated from the power semiconductor switch (10) moves through the heat sink (21) and inverter case (20) to the coolant (40), thereby having the effect of dissipating heat from the power semiconductor switch (10).

In addition, a temperature sensor (50) is provided on the lower surface of the PCB substrate (30) and can be provided at a position between the power semiconductor switches (10).

Accordingly, when examining the heat transfer path according to this, heat generated from the power semiconductor switch (10) is transferred to the PCB substrate (30) along the lead wire (11), and overheating of the power semiconductor switch (10) can be detected through the temperature sensor (50).

However, since the temperature sensor (50) is a thermistor type temperature sensor that estimates the temperature by the change in the internal resistance value as the surrounding temperature changes, there is a problem that when the junction temperature of the power semiconductor switch (10) rises rapidly, the temperature followability is low, and the power semiconductor switch (10) may exceed the guaranteed temperature, resulting in damage to the power semiconductor switch (10).

An electric compressor (not shown) according to the present invention to solve these problems may include a compression unit, a motor unit, and an inverter unit (1000).

The compression unit can suck in refrigerant and compress it.

The motor unit may be provided on one side of the compression unit and may drive the compression unit based on power supplied from an external source.

The inverter unit (1000) can be provided on one side of the motor unit and can control the motor unit.

Referring to FIGS. 3 and 4 below, the inverter unit (1000) included in the electric compressor according to the present invention will be described in detail.

Figure 3 is a side schematic diagram of an inverter unit (1000) according to one embodiment of the present invention.

FIG. 4 is a drawing showing the lower surface of a PCB substrate (300) included in an inverter unit (1000) according to one embodiment of the present invention.

As shown in FIGS. 3 and 4, an inverter unit (1000) according to one embodiment of the present invention includes a power semiconductor switch (100), a fixing member (200), and a PCB substrate (300).

There is at least one power semiconductor switch (100), and there may be multiple power semiconductor switches.

The PCB substrate (300) is a printed circuit board (PCB) on which various electronic components are mounted and electrical wiring is formed inside. This can be provided on one side of the power semiconductor switch (100).

The fixing member (200) can be directly or indirectly connected to the other surface of the power semiconductor switch (100), and specifically, can be physically connected. Accordingly, the power semiconductor switch (100) can be fixed. Specifically, the fixing member (200) is not limited to a member that can fix the power semiconductor switch (100), such as an inverter case or a heat sink. More specifically, a lead wire (110) is formed in the power semiconductor switch (100), and can be connected to the fixing member (200) through a bolt (B). In addition, the coolant (400) is located at the lower portion of the fixing member (200) and serves to cool the heat generated from the power semiconductor switch (100).

In addition, the electric compressor according to the present invention may further include a control unit (not shown).

The control unit controls the power semiconductor switch (100). Specifically, the control unit may be provided on the PCB substrate (300) or on a separate substrate. Additionally, it may be provided on the outside of the inverter unit (1000).

At this time, the PCB substrate (300) may include at least one non-contact temperature sensor (500) that provides temperature information of the power semiconductor switch (100). Here, inclusion means that the temperature sensor (500) is mounted on the PCB substrate (300). At least a part of the temperature sensor (500) may be insert-fixed to the PCB substrate (300) or may be surface-mounted. Preferably, the temperature sensor (500) is mounted on the surface of the PCB substrate (300), and it is preferable that it be mounted on a surface facing the power semiconductor switch (100).

Preferably, the temperature sensor (500) may be an infrared temperature sensor, and at this time, the response speed of the infrared temperature sensor may be 20 mS or more. Meanwhile, the temperature information may include the surface temperature of the power semiconductor switch (100).

When the temperature of the power semiconductor switch changes abruptly, a contact-type temperature sensor such as a thermistor has its own thermal time constant (the time required for the difference between the initial temperature and the final temperature to change by 63.2% from the initial temperature), and thus provides a time-delayed temperature measurement value, which limits its ability to measure abrupt temperature changes. Accordingly, the control unit must have a larger margin in consideration of the time delay so that the power semiconductor switch is not overheated, and thus the control range is limited so that the power semiconductor switch operates only up to a relatively lower temperature.

On the other hand, since an infrared temperature sensor can have a much smaller time delay than the contact-type temperature sensor, by employing a non-contact temperature sensor such as an infrared temperature sensor, even when the temperature of the power semiconductor switch changes rapidly, the changing temperature can be detected quickly, and accordingly, the control unit can quickly control the operation of the power semiconductor switch (100) based on the temperature information which is the output of the temperature sensor (500), thereby better protecting the power semiconductor switch (100) and securing a wider control area.

Meanwhile, the temperature sensor (500) may be provided on one side and the other side of the PCB substrate (300), and the other side may mean a side facing the power semiconductor switch (100). At this time, the temperature sensor (500) may be mounted on the surface of the PCB substrate (300). In the conventional case, a temperature sensor is provided in the power semiconductor switch to sense the temperature of the power semiconductor switch. In this case, a separate cable must be provided between the power semiconductor switch and the PCB substrate, and there is a problem that the insulation may be broken due to a voltage difference between the power semiconductor switch (high voltage) and the cable (low voltage), thereby damaging the PCB substrate, and that the covering of the cable may be damaged because the temperature is high. However, as in the present invention, by mounting the temperature sensor (500) on the surface of the PCB substrate (300) and forming an integrated structure, a separate cable connection is unnecessary and there is an effect of being able to measure the temperature of the power semiconductor switch (100).

Specifically, the temperature sensor (500) can sense the surface temperature of the power semiconductor switch (100).

In the case of a conventional thermistor temperature sensor (50), it could be placed at an electrode location where temperature is concentrated. However, the infrared temperature sensor (500) of the present invention can be placed at a location that is determined without being restricted by this.

In more detail, the temperature sensor (500) may be provided at a location corresponding to the location with the highest temperature on the surface of the power semiconductor switch (100).

In addition, the power semiconductor switch (100) may include at least one semiconductor chip, and accordingly, the temperature sensor (500) may be provided at a position corresponding to the center of the semiconductor chip. Preferably, it may be provided at a position corresponding to the center of an area having the highest amount of heat generation among the semiconductor chips.

Additionally, the PCB substrate (300) may include a plurality of temperature sensors (500) for each of the plurality of power semiconductor switches (100).

In addition, the temperature sensor (500) may be provided on the upper portion of a power semiconductor switch (100) among a plurality of power semiconductor switches (100) whose heat concentration is expected to be higher than a predetermined standard.

Meanwhile, the inverter unit (1000) according to the present invention may further include a heat sink (210) between the power semiconductor switch (100) and the fixing member (200). Accordingly, the PCB substrate (300) may further include a temperature sensor that measures the temperature of the heat sink (210). Accordingly, the control unit may control the power semiconductor switch (100) based on the temperature of the heat sink (210) and the temperature of the power semiconductor switch (100).

Looking at the heat transfer path of the inverter unit (1000) according to the present invention, the heat generated from the power semiconductor switch (100) moves to the coolant (400) through the heat sink (210) and the fixing member (200), thereby having the effect of dissipating heat from the power semiconductor switch (100).

In addition, when examining the heat transfer path for detecting overheating of the power semiconductor switch (100), heat generated in the power semiconductor switch (100) is transferred to the temperature sensor (500) through the surface of the power semiconductor switch (100), so that the temperature sensor (500) can detect overheating of the power semiconductor switch (100).

Therefore, the surface temperature of the power semiconductor switch (100) can be measured through the temperature sensor (500). This can improve temperature followability compared to a conventional thermistor type temperature sensor, and thus can detect rapid temperature changes.

At this time, the control unit can measure the temperature more accurately based on the output of the temperature sensor (500).

Specifically, based on the surface temperature measured by the temperature sensor (500), the junction temperature of the power semiconductor switch (100) can be calculated through a thermal resistance formula of the junction of the power semiconductor switch (100) and the fixing member (200). More specifically, the junction temperature of the power semiconductor switch (100) can be calculated by multiplying the surface temperature measured by the temperature sensor (500) by a predetermined constant.

Furthermore, the time delay can be compensated for by estimating the junction temperature of the power semiconductor switch (100) by considering the thermal time constant between the junction and the surface of the power semiconductor switch (100) and the rate of change of the measured surface temperature.

Therefore, the inverter operating range can be expanded by accurately measuring the temperature of the power semiconductor switch (100), thereby improving the performance of the product including the inverter unit (1000) of the present invention.

In addition, the control unit can control the power semiconductor switch (100) to operate only within a predetermined temperature range based on the generated junction temperature of the power semiconductor switch (100).

Specifically, the control unit can detect high temperature of the power semiconductor switch (100) in advance before reaching the upper limit temperature of 175 degrees based on the change trend of the junction temperature value calculated from the temperature sensor (500).

Preferably, in order to prevent the device from exceeding the guaranteed temperature (175 degrees) due to a rapid temperature rise in a low-speed, high-load state and poor heat dissipation condition, the control unit can stop the switching operation to prevent the power semiconductor switch (100) from being damaged.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the specific embodiments described above. That is, those skilled in the art to which the present invention pertains may make numerous changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications should be considered as equivalents and fall within the scope of the present invention.

1000 : Inverter part
10, 100 : Power Semiconductor Switch
11, 110 : Lead line
20, 200 : Fixed member (inverter case)
21, 210 : Heat sink
30, 300 : PCB board
40, 400 : Refrigerant
50, 500 : Temperature sensor

Claims (13)

A compression unit that compresses the refrigerant;
A motor unit for driving the above compression unit; and
Including an inverter section that controls the above motor section;
The above inverter part,
At least one power semiconductor switch;
A fixing member that is directly or indirectly physically connected to one side of the power semiconductor switch and fixes the power semiconductor switch; and
A PCB substrate provided on one side of the power semiconductor switch; including:
The above PCB board,
At least one non-contact temperature sensor that provides temperature information of the power semiconductor switch without contacting the power semiconductor switch;
An electric compressor characterized by:
In the first paragraph,
The response speed of the above temperature sensor is 20mS or more.
An electric compressor featuring:
In the first paragraph,
The above temperature information includes the surface temperature of the power semiconductor switch.
An electric compressor featuring:
In the first paragraph,
The above temperature sensor is an infrared temperature sensor.
An electric compressor featuring:
In the first paragraph,
The above temperature sensor,
Mounted on the surface of the above PCB substrate, but mounted on the surface facing the power semiconductor switch
An electric compressor featuring:
In the first paragraph,
The above temperature sensor,
Provided at a location corresponding to the location with the highest temperature on the surface of the above power semiconductor switch
An electric compressor characterized by:
In the first paragraph,
The above power semiconductor switch comprises at least one semiconductor chip,
The above temperature sensor,
It is provided at a location corresponding to the center of the area with the highest heat generation among the above semiconductor chips.
An electric compressor characterized by:
In the first paragraph,
The above PCB board,
Comprising a plurality of temperature sensors per said power semiconductor switch
An electric compressor characterized by:
In the first paragraph,
The above temperature sensor,
A plurality of power semiconductor switches are installed at a location where the heat concentration is expected to be higher than a predetermined standard.
An electric compressor featuring:
In the third paragraph,
Further comprising a control unit for controlling the power semiconductor switch based on the above temperature information;
The above control unit,
Calculating the junction temperature of the power semiconductor switch based on the surface temperature sensed by the temperature sensor and the thermal resistance formula of the junction of the power semiconductor switch and the fixed member.
An electric compressor characterized by:
In Article 10,
The above control unit,
Calculating the junction temperature of the power semiconductor switch by multiplying the surface temperature sensed by the temperature sensor by a predetermined constant.
An electric compressor characterized by:
In Article 10,
The above control unit,
Controlling the power semiconductor switch to operate only below a predetermined temperature range based on the junction temperature of the power semiconductor switch produced
An electric compressor characterized by:
In Article 10,
Further comprising a heat sink between the power semiconductor switch and the fixing member;
The above PCB board,
Further comprising a temperature sensor for measuring the temperature of the heat sink;
The above control unit controls the power semiconductor switch based on the temperature of the heat sink and the temperature of the power semiconductor switch.
An electric compressor characterized by:

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