JP2004225580A - Shunt resistor installed inverter integration type electric compressor and shunt resistor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter integration type electric compressor including a shunt resistor excellent in reliability and capable of accurate current detection. <P>SOLUTION: Welding terminals 101 provided on both end parts of shunt resistors R1, R2, R3 is joined to a bus bar with welding. Since voltage drop detection terminal 102 of the shunt resistors R1, R2, R3 are arranged inside of the welding terminals 101, there is no influence of variation of electrical resistance due to variation of welding operation of the welding terminal. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric compressor for a vehicle, and more particularly, to an improvement in an inverter unit thereof.
[0002]
[Prior art]
2. Description of the Related Art For cooling a vehicle at idle stop, an electric compressor for a vehicle has been proposed which is provided with a motor for driving the compressor for vehicle air conditioning integrally with the compressor. In this type of vehicle electric compressor, a synchronous motor (brushless DC motor) is employed in order to finely control the motor rotation speed according to the air conditioning load.
[0003]
In order to drive this synchronous motor with a vehicle-mounted battery, an inverter circuit that converts DC power into three-phase AC power, a control circuit that controls the switching of the inverter circuit, and a high-frequency current derived from the switching of the inverter circuit are used. A complicated capacitor including a smoothing capacitor to be reduced, a current sensor for detecting a motor current and the like, and large and small wirings for connecting them, and an inverter circuit unit requiring high-speed high-speed switching are required.
[0004]
The three-phase AC wiring connecting the inverter circuit section and the electric compressor to which the three-phase PWM control power is supplied from the inverter circuit section preferably contains as much switching noise as possible, and is therefore preferably shortened as much as possible. An inverter-integrated electric compressor in which a circuit unit is integrated with an electric compressor has been proposed.
[0005]
As a current sensor, a shunt resistance type current detection technology in which a low-resistance current detection resistor (hereinafter also referred to as a shunt resistor) is connected in series in a wiring to be detected and current is detected using the voltage drop is disclosed in Patent Document 1 and the like. Are known.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-48821
[Problems to be solved by the invention]
However, since the inverter-integrated electric compressor described above has very strong vibration due to the refrigerant compression and expansion operations of the compressor mechanism, the connection between the wiring through which the current to be detected flows and the shunt resistor is a normal connection. Techniques such as screw tightening cannot be adopted. As this wiring, a bus bar is usually used because a large current flows.
[0008]
Therefore, in order to electrically connect the shunt resistor mounted on the inverter circuit portion of the inverter-integrated electric compressor to the bus bar, it is necessary to weld both ends of the shunt resistor to two ends of the wiring. Both ends of the shunt resistor are entirely connected to the bus bar so as to realize the joint strength that can withstand the vibration so that the vibrating force of the vibration acting on the normal mass is transmitted to the welded part and this welded part does not break due to fatigue. It is necessary to increase the welding area by welding to the welding end.
[0009]
However, the resistance value of the welded portion changes depending on the degree of build-up during welding, the variation in the shape of the shunt resistance and the bus bar, and the degree of contact, and as a result, the electrical resistance at both ends of the shunt resistance is changed. There is a problem that the resistance value varies due to welding.
[0010]
In addition, the above-mentioned shunt resistance and the vibrating force of the vibration acting on the bus bar connected to the shunt resistance act on this welded part for a long period of time, so that the welded part is fatigued and its electric resistance value changes, There is also a possibility that heat is generated and the electric resistance value of the shunt resistor changes.
[0011]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an inverter-integrated electric compressor having a shunt resistor that is excellent in reliability and capable of detecting current with high accuracy.
[0012]
[Means for Solving the Problems]
The inverter-integrated electric compressor with a shunt resistor according to claim 1 is a housing, a compressor housed in the housing and a motor for driving the compressor, and is fixed to the housing and converts DC power to polyphase AC power. And an inverter circuit unit for supplying power to the motor, wherein the inverter circuit unit is an inverter-integrated electric compressor equipped with a shunt resistor having a current detection low-resistance element connected in series to a line through which a current to be detected flows.
Both ends of the low-resistance element for current detection are a pair of welding terminals individually welded to the pair of wirings, and the voltage drop detection disposed apart from the welding portion and not including the pair of welding portions. And a pair of voltage drop detecting terminals for detecting a voltage drop of the main part of the terminal for use.
[0013]
According to the present invention, the following effects can be obtained.
[0014]
First, despite being fixed to the inverter circuit part installed in the electric compressor that generates strong vibration, the shunt resistor is welded to the bus bar by welding, so it has good joining reliability and Since the voltage drop detecting terminal does not include variations in the voltage drop between the welding terminal and the welded portion, it is possible to realize highly accurate current detection.
[0015]
In a preferred aspect, the inverter circuit section is integrated with a number of power switching elements for a multi-phase inverter circuit configuration fixed to the housing directly or via a cooling base plate while being electrically insulated from each other by the resin molding. And a bus bar assembly that is arranged above the power switching element and constitutes a large current wiring of the inverter circuit section, and a control circuit section for controlling the power switching element is mounted and mounted above the bus bar assembly. A printed circuit board to be disposed, wherein the pair of welding terminals of the current detection low-resistance element are mounted on main surfaces of a predetermined pair of bus bars of the bus bar assembly and welded, and the current detection is performed. The pair of voltage drop detection terminals of the low resistance element for The through hole of the substrate through is characterized by being soldered to the conductor pattern of the printed circuit board.
[0016]
That is, according to this aspect, the low-resistance element for current detection (shunt resistor) is configured such that the lower portions of both ends are fixed to one bus bar protruding from the bus bar assembly having high rigidity by resin molding, and the upper portions of both ends are formed. Also, each is fixed to the hole of the printed circuit board, the vibration of the electric compressor, the main part of the shunt resistor in the longitudinal direction (horizontal direction), perpendicular to it (horizontal direction), vertical excitation force respectively And the vibration of the electric compressor can reduce the fatigue fracture given to the welded portion of the shunt resistance, and the welded portion can be downsized.
[0017]
In a preferred aspect, the pair of welding terminals of the current detection low-resistance element are substantially perpendicular and in the same direction from both ends of the main plate of the current detection low-resistance element with respect to a main surface direction of the main plate. It protrudes and is mounted on the bus bar. Thus, the shunt resistor can be easily held in the predetermined position on the bus bar, so that the welding operation of the shunt resistor can be simplified. In addition, since the shunt resistor rises from the bus bar by the height of its main part, the length of the voltage drop detection terminal can be shortened, and downsizing of the shunt resistor and reduction in manufacturing cost can be realized.
[0018]
A shunt resistor device according to the present invention includes a shunt resistor connected in series to a wire to generate a voltage drop proportional to a current in the wire, and a heat sink that is close to the shunt resistor and serves as a cooling source. It is characterized in that it is in close contact with the surface of the heat sink via a heat transfer member having electrical insulation and heat conductivity.
[0019]
With this configuration, it is possible to suppress the electric resistance value of the shunt resistor through which a large current flows from fluctuating due to the heat generation, and realize a highly accurate current detection with a simple configuration.
[0020]
In a preferred aspect, the heat transfer member has a first heat transfer member having electrical conductivity and heat conductivity electrically connected to the shunt resistor, and a first heat transfer member and the heat sink. A second heat transfer member made of an electrically insulating resin material interposed therebetween.
[0021]
With this configuration, the heat generated by the shunt resistor can be released to the heat sink, so that the contact of the cooling air with the shunt resistor can be improved, and the temperature of the shunt resistor can be further reduced.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of an inverter-integrated electric compressor for a vehicle refrigeration cycle apparatus to which the present invention is applied will be described with reference to the drawings. In each of the drawings, members and lines are omitted as appropriate.
(Example 1)
FIG. 1 shows an electric circuit diagram of the inverter-integrated electric compressor.
[0023]
1 is a battery, 2 is an inverter circuit unit, and 3 is a motor for driving a compressor. The inverter circuit unit 2 includes six MOS transistors 21 constituting the three-phase inverter circuit 20, a shunt resistor R1 interposed between the U-phase lower arm MOS transistor 21 and the lower DC line 22, and a W-phase A shunt resistor R2 provided between the lower arm MOS transistor 21 and the lower DC line 22, a shunt resistor R3 provided in series between the lower DC line 22, and an inverter control for controlling the MOS transistor 21; Circuit (control circuit unit) 23.
[0024]
Since the configuration, operation itself, and the function of each shunt resistor of this type of inverter circuit section 2 are well known, further description is omitted.
[0025]
Both ends of the shunt resistors R1 and R2 are individually welded to a bus bar connected to one main terminal of the MOS transistor 21 of the lower arm and a bus bar forming the lower DC line 22, and both ends of the shunt resistor R3 are connected to the lower DC line. The two shunt resistors are individually welded to two bus bars 22, and both ends of these shunt resistors are supplied with a potential to an inverter control circuit 23 by a current detection line 24.
[0026]
FIG. 2 shows an equivalent circuit of the shunt resistors R1, R2, and R3. Ra is the electric resistance between the pair of current detection lines 24, Rb is the electric resistance from the current detection line 24 to the weld, Rc is the electric resistance of the weld, and Re is the electric resistance from the weld to the busbar. Each shunt resistor R1, R2, R3 has these electric resistance values.
[0027]
FIG. 3 shows the overall shape of the inverter-integrated electric compressor of this embodiment, and FIG.
[0028]
Reference numeral 4 denotes a housing formed by aluminum die-casting. The housing 4 contains a motor 3 and a compressor driven by the motor. A rectangular pedestal portion 40 is formed on the upper peripheral wall of the housing 4, and each MOS transistor 21 having a module shape is fixed to the upper surface of the pedestal portion 40 via an insulating film 41. Each of the bus bars of the bus bar assembly 5 to be described later is welded to the end of the bus bar to be connected to itself.
[0029]
A rectangular block-shaped bus bar assembly 5 manufactured by resin insert molding is fixed on the pedestal portion 40 by screws, and in the internal space of the bus bar assembly 5, a large number of bus bars constituting each wiring of the inverter circuit portion are provided. Wired. A printed circuit board 6 on which an inverter control circuit 23 is mounted is fastened by screws to an upper portion inside the bus bar assembly 5, and a metal cover plate 7 is fixed to an upper end opening of the bus bar assembly 5. , The printed circuit board 6 and the MOS transistor 21 are sealed. Shunt resistors R1, R2, and R3 are fixed to the end of the bus bar protruding into the bus bar assembly 5. An exploded perspective view of the bus bar assembly 5 is shown in FIG. L is a choke coil, and C is a smoothing capacitor.
[0030]
As shown in FIG. 5, the shunt resistors R1, R2, and R3 are formed in a ladder shape by an alloy having a predetermined composition (for example, a copper-nickel alloy). It has a pair of welding terminals 101 provided at right angles to the main part at both ends and a voltage drop detecting terminal 102 projecting upward at a predetermined distance from the upper end of the ladder-shaped main part.
[0031]
The lower surface of the plate-shaped welding terminal 101 extends horizontally, and is formed by bending the projection of the plate-shaped main part 100. The pair of welding terminals 101 are welded to the bus bar. The pair of voltage drop detecting terminals 102 are located sufficiently inside the welding terminal 101 and protrude upward from the upper part of the main part 100, penetrate through a through hole (not shown) of the printed circuit board 6, and The copper foil (conductive pattern) is soldered around the hole.
[0032]
(Modification)
FIG. 6 shows a modification of the shunt resistors R1, R2, and R3.
[0033]
In this modification, the welding terminals 201 of the shunt resistors R1, R2, R3 and the main part 200 are formed substantially in parallel, and the voltage drop detection terminal 202 protrudes upward from the side surface of the main part 200.
[0034]
(Modification)
FIG. 7 shows another modification of the shunt resistors R1, R2, and R3.
[0035]
In this modification, the welding terminal 301 of the shunt resistor R1 and the main part 300 are formed at substantially right angles, but the main part 300 is formed in a plate shape and is not formed in a ladder shape. The voltage drop detection terminal 302 is formed by pressing both ends of the main part 300 to be elongated by press molding, and protrudes upward.
[0036]
FIG. 8 shows the connection between the shunt resistor R1 and the bus bars 303 and 304, and the connection between the shunt resistor R1 and the printed circuit board 6.
[0037]
Projections 305, 306 are provided at the welding ends of the bus bars 303, 304, and a welding terminal 301 of the shunt resistor R1 is placed so as to cover the projections 305, 306. Welding is performed from the side of the projections 305, 306. Has been done. The voltage drop detection terminal 302 of the shunt resistor R1 is inserted into the hole 60 of the printed circuit board 6.
(Example 2)
Second Embodiment A shunt resistor R1 according to a second embodiment will be described with reference to FIG. FIG. 9 is a sectional view of the shunt resistor R1.
[0038]
A pair of copper busbars (heat transfer members) 401 (only one is shown) are fixed on the pedestal portion 40 via a resin film 400 so as to be electrically insulated from the pedestal portion 40. As shown in FIG. 8, a welding terminal 401 of the shunt resistor R1 is welded to the member 401.
[0039]
By doing so, the heat generated by the shunt resistor R1 can be satisfactorily dissipated to the pedestal portion 40 of the housing 4, and a change in the electric resistance value due to a rise in the temperature of the shunt resistor R1 can be suppressed.
[0040]
In this embodiment, the heat of the shunt resistor R1 is radiated to the pedestal portion 40 through the bus bar 401 and the resin film 400. You may. Further, the main part of the shunt resistor R1 may be directly adhered to the pedestal part 40 or the bus bar through the resin film.
[0041]
(Example effects)
According to the above-described embodiments, the shunt resistance is welded to the bus bar despite being fixed to the inverter circuit unit provided in the electric compressor that generates a strong vibration, so that good joining reliability is obtained. In addition, since the terminal for detecting the voltage drop of the shunt resistor does not include the variation in the voltage drop between the welding terminal and the welded portion, high-precision current detection can be realized.
[0042]
The low-resistance element (shunt resistor) for current detection has a lower end at both ends fixed to one bus bar protruding from a bus bar assembly having high rigidity by resin molding, and an upper part at both ends is also provided with a hole in a printed circuit board. The main part of the shunt resistor, due to the vibration of the electric compressor, has good vibration resistance against its longitudinal (horizontal), perpendicular (horizontal), and vertical vibrating forces. Therefore, it is possible to reduce the fatigue fracture that the vibration of the electric compressor gives to the welded portion of the shunt resistance, and to reduce the size of the welded portion.
[0043]
In addition, since the shunt resistor is easily held in a predetermined position on the bus bar, welding work of the shunt resistor can be simplified.Since the shunt resistor rises only from the bus bar to the height of its main part, it is used for voltage drop detection. The length of the terminal can be shortened, and downsizing of the shunt resistor and reduction in manufacturing cost can be realized.
[0044]
A shunt resistor connected in series to the wiring to generate a voltage drop proportional to the current of the wiring; and a heat sink adjacent to the shunt resistance and serving as a cooling / heating source. Since it is in close contact with the surface of the heat sink through a heat transfer member having conductivity, it is possible to suppress the electric resistance value of the shunt resistor through which a large current flows from fluctuating due to the heat generation, and perform a highly accurate current detection with a simple configuration. Can be realized.
[Brief description of the drawings]
FIG. 1 is an electric circuit diagram of an inverter-integrated electric compressor according to a first embodiment.
FIG. 2 is an equivalent circuit of a shunt resistor.
FIG. 3 is a perspective view showing the overall shape of the inverter-integrated electric compressor of FIG.
FIG. 4 is an exploded perspective view of the inverter-integrated electric compressor shown in FIG.
FIG. 5 is an exploded perspective view showing the bus bar assembly.
FIG. 6 is an exploded perspective view showing a modification of the shunt resistor.
FIG. 7 is an exploded perspective view showing a modification of the shunt resistor.
FIG. 8 is a perspective view showing a modification of the shunt resistor.
FIG. 9 is a cross-sectional view showing heat dissipation of a shunt resistor.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 battery 2 inverter circuit section 3 motor for driving compressor 4 housing 5 busbar assembly 6 printed circuit board 20 three-phase inverter circuit 21 MOS transistor (power switching element)
22 Low-level DC line (bus bar)
23 Inverter control circuit 40 Base 41 Insulating film 100 Main part 101 of shunt resistance Welding terminal 102 Terminals R1, R2, R3 for voltage drop detection Shunt resistance (low resistance element for current detection)

Claims (5)

A housing, a compressor housed in the housing and a motor driving the compressor, and an inverter circuit unit fixed to the housing and converting DC power to polyphase AC power and supplying power to the motor,
The inverter circuit unit is an inverter-integrated electric compressor equipped with a shunt resistor having a low-resistance element for current detection connected in series to a line through which a current to be detected flows,
Both ends of the low-resistance element for current detection are a pair of welding terminals individually welded to the pair of wirings, and the voltage drop detection disposed apart from the welding portion and not including the pair of welding portions. An inverter-integrated electric compressor equipped with a shunt resistor, comprising: a pair of voltage drop detecting terminals for detecting a voltage drop of a main part of the terminal. The inverter-integrated electric compressor with a shunt resistor according to claim 1,
The inverter circuit unit includes:
A number of power switching elements for a polyphase inverter circuit configuration fixed directly to the housing or via a cooling base plate;
A busbar assembly which is integrated with the power switching element while being electrically insulated from each other by the resin molding and arranged above the power switching element, and constituting a large current wiring of the inverter circuit portion;
A printed circuit board on which a control circuit unit for controlling the power switching element is mounted and arranged above the bus bar assembly;
Has,
The pair of welding terminals of the current detection low resistance element are mounted and welded on the main surfaces of a predetermined pair of bus bars of the bus bar assembly,
The pair of voltage drop detection terminals of the low resistance element for current detection protrude upward, penetrate through holes of the printed circuit board, and are soldered to conductor patterns of the printed circuit board. Shunt resistor equipped inverter integrated electric compressor. The inverter-integrated electric compressor with a shunt resistor according to claim 2,
The pair of welding terminals of the low-resistance element for current detection protrude from both ends of the main plate portion of the low-resistance element for current detection in a direction substantially perpendicular to the main surface direction of the main plate portion and in the same direction. Inverter-integrated electric compressor equipped with a shunt resistor, which is mounted on a vehicle. A shunt resistor connected in series to the wiring to generate a voltage drop proportional to the current in the wiring,
A heat sink forming a cold source in proximity to the shunt resistor;
With
The shunt resistor device is characterized in that the shunt resistor is in close contact with the surface of the heat sink via a heat transfer member having electrical insulation and heat conductivity. The shunt resistance device according to claim 4,
The heat transfer member,
Electrical conductivity electrically connected to the shunt resistor, a first heat transfer member having thermal conductivity,
A second heat transfer member made of an electrically insulating resin material interposed between the first heat transfer member and the heat sink,
A shunt resistance device comprising:

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