JPH08126346A - Power converter - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a power converter that is small in size, excellent in cooling performance, and easy to handle. A power converter comprising an electrolytic capacitor for smoothing a voltage from a battery and a power semiconductor element for converting the voltage from the capacitor into a power to control an AC motor. A heat sink for cooling is arranged between the power semiconductor device and the power semiconductor device. [Effect] It is possible to obtain a power converter that is small in size, excellent in cooling performance, and easy to handle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter, and more particularly to a power converter suitable for electric vehicles.

[0002]

2. Description of the Related Art Conventionally, a technique for forcibly cooling a power converter for an electric vehicle using a liquid such as water is known from Japanese Patent Laid-Open No. 292703/1993.

In the above technique, the heat sink and the power converter are arranged in parallel on the axis of the electric motor main body to forcibly cool the heat sink for the electric power converter and the electric motor main body.

[0004]

The larger the contact area between the heat sink and the power conversion element, the better the cooling of the power conversion device, which is generally determined by the size of the power conversion element.

In the heat sink, the larger the inner surface area of the cooling liquid passage is, the better. It is preferable that the flow velocity of the cooling liquid in the cooling liquid passage is fast, but it is important that the flow velocity distribution in each pass is uniform. It is well known that there is.

However, in the above-mentioned prior art, the flow velocity in the inner passage is higher than that in the outer passage, and the flow velocity distribution is unbalanced. Further, there is a problem that the cooling capacity is small because the cooling passage is flat and the inner surface area of the cooling water cannot be large.

Further, since the smoothing capacitor is provided on the outer circumference of the switching element, the bus bar becomes long. Since the smoothing capacitor and the switching element have different heights, a height adjusting spacer is required.

An object of the present invention is to provide a power converter that is small and has excellent cooling performance.

Another object of the present invention is to provide a power converter which is small in size, excellent in cooling performance, and easy to handle.

[0010]

The present invention comprises an electrolytic capacitor for smoothing the voltage from a battery, and a power semiconductor element for converting the voltage from the capacitor into electric power to control an AC electric motor. The power conversion device is achieved by disposing a heat sink for cooling between the electrolytic capacitor and the power semiconductor element.

One aspect of the present invention is a power conversion device comprising an electrolytic capacitor for smoothing a voltage from a battery and a power semiconductor element configured to control the AC motor by converting the voltage from the capacitor into electric power. A heat sink for cooling having a polygonal shape between the electrolytic capacitor and the power semiconductor element, having an insertion hole for mounting an electrolytic capacitor in the center, and further having a cooling liquid passage connected to the forced circulation passage. It is achieved by arranging and mounting power semiconductor elements on the polygonal surface.

Preferably, the heat sink is hexagonal and the current sensor is arranged and fixed on the heat sink between the power semiconductor elements.

[0013]

The cooling liquid guided from the inlet passage is guided from the laterally extending annular passage to the annular passage connected to the outlet passage through the vertical cooling passage. The cooling passage cooling liquid is generated in the electrolytic capacitor and the IGBT and removes the heat generated in the heat sink to cool it. The heated cooling liquid is forcibly circulated by a pump or the like to be cooled and reused.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic power system diagram of a drive system for an electric vehicle using the power converter of the present invention.
This is a system in which the power from the battery 1 is converted into a three-phase AC by the power converter 2 and supplied to the AC motor 3.

The direct current from the battery 1 is composed of a plurality of electrolytic capacitors 4, more specifically, three cylindrical capacitors which are assembled in a triangular shape to smooth the voltage and current and to power semiconductor elements of each phase [IGBT hereinafter. (Insulated Gate Bipolar
Transistor)] is sent to 5. In the IGBT, a sine wave three-phase AC power supply is generated by switching ON and OFF to supply power to the AC motor 3.

The configuration of the power converter will be described with reference to FIGS. 2 and 3.

The heat sink 6 for cooling is made of an aluminum material having good heat dissipation and good workability, and is extruded into a hexagonal shape. At the same time, as shown in FIG. Mounting insertion hole 6a,
Longitudinal (longitudinal) along the outer wall surface of the IGBT mounting surface to be described later
A coolant passage 6b extending in the direction is formed. As shown in FIG. 5, the cooling liquid passage 6b joins at its upper and lower ends with annular communication passages 6c and 6d so as to communicate with the inlet passage 7a and the outlet passage 7b.

Since the communication passages 6c and 6d on both ends of the cooling heat sink 6 are open grooves in the processed state, they are sealed by welding or bonding the periphery with metal seal plates 8a and 8b later. A cooling liquid passage is formed.

FIG. 4 is a state diagram in which the electrolytic capacitors 4 are inserted into the heat sink 6 for cooling, and the electrolytic capacitors 4 are inserted and fitted into the electrolytic capacitor attachment insertion holes 6a, and the electrolytic capacitors provided in the electrolytic capacitors 4 are provided. Of the capacitor
Place the (-) terminal 41 in the center of the heat sink 6 for cooling (+)
The terminals 42 are arranged on the outer peripheral portion so as to be point-symmetric with respect to each other by 120 °.

Each terminal 41 of the above-mentioned electrolytic capacitor 4,
A hexagonal (+) side closed loop bus bar 9 made of a flat plate is fitted into 42 and the nut is tightened. Next, the closed loop busbar 10 on the (-) side, which has the same shape and is slightly smaller, is fitted through the insulating member 43 to form a two-story structure and the nuts are tightened.

Each of the IGBTs 5 has a mounting surface 6e, which is an outer peripheral surface of the heat sink 6, and screws 5a and 5a, respectively.
It is attached and fixed at b. The IGBT (+) side terminals 5c and 5d and the electrolytic capacitor (+) side closed loop bus bar 9
And busbar 11 are connected, and IGBT (-) side terminal 5
e, 5f and the electrolytic capacitor (-) side closed loop bus bar 10 are connected by a bus bar 12. This (+) (-) bus bar 11,1
The U, V, and W phases are each formed in an L shape, and have the same part shape for each phase. Further, R is a snubber resistor for absorbing noise, which is arranged between the power semiconductor elements and fixed to the same surface as the mounting surface of the elements.

Since the bus bar is composed of the same parts for each phase, the U-phase, V-phase and W-phase can be carried out by the same work.

Bus bars 14 arranged along the side surface of FIG.
Similarly, one end is connected to the terminals 5g and 5h, and the other end is connected to the lead wire holding member 15 mounted on the current sensor mounting surface 6f. The bus bar 14 is a space portion of the current sensor 16 like a normal current sensor. Is provided to penetrate. In the lead wire holding member 15, the harness 17 and the bus bar 14 are fastened together, and the harness 17 is connected to the input end of the AC electric motor 3.

In the embodiment, two IGBTs 5 are used, but one or more may be used as required. The same applies to electrolytic capacitors.

Water or oil is generally used as the cooling liquid, and the cooling water is forcibly sent to the cooling heat sink inlet pipe 7a by the pump 18 and flows through the cooling liquid passages 6c and 6d of the cooling heat sink 6 for cooling. It is sent to the heat sink outlet pipe 7 b, cooled by the radiator 19, and circulated to the pump 18. Therefore, the cooling water cools the electrolytic capacitor insertion hole 6a, the IGBT mounting surface 6e, and the current sensor mounting surface 6f, respectively.

A cooling heat sink inlet pipe 7a and a cooling heat sink outlet pipe 7b are provided on the current sensor mounting surface 6f of the cooling heat sink.

The mounting surface 6f is disposed on a hexagonal space, and is provided on a power semiconductor element connected to the electrolytic capacitor via a busbar and a symmetrical surface of the power semiconductor element. Therefore, the cooling water cools the electrolytic capacitor insertion hole 6a, the IGBT mounting surface 6e, and the current sensor mounting surface 6f, respectively.

With such a structure, the material yield of the bus bar on the electrolytic capacitor side can be very good and the cost can be reduced.

FIG. 7 shows another embodiment of the electrolytic capacitor bus bar.

When the heights of the electrolytic capacitor (+) terminal and the (-) terminal are the same, the insulation distance L required between the electrolytic capacitor (+) side bus bar 44 and the electrolytic capacitor (-) side bus bar 45.
As long as this is ensured, there is no problem with the electric resistance on the (+) side (-) side.

According to the embodiment of the present invention, the temperature rise of the electrolytic capacitor can be reduced by about 10 ° C., which greatly contributes to the extension of the life of the capacitor. Moreover, the current imbalance in each phase can be almost eliminated. (Generally, current imbalance 20
There is about%. ) Further, since the bus bars for each phase can be formed in the same shape and the same work can be performed for each phase, the number of assembly steps can be reduced by 20% for the same performance.

Further, since the electrolytic capacitor, the heat sink for cooling, the IGBT, etc. can be arranged in the shortest distance, it is 35%.
The above miniaturization is possible.

[0033]

According to the present invention, a heat sink for cooling is arranged between an electrolytic capacitor and a power semiconductor element, and a cooling liquid is forcedly circulated, so that a power converter having a small size and excellent cooling property can be obtained.

The present invention has a polygonal shape between the electrolytic capacitor and the power semiconductor element, has an insertion hole for mounting the electrolytic capacitor in the center, and further has a cooling liquid passage connected to the forced circulation passage for cooling. By arranging the heat sink and mounting the power semiconductor element on the polygonal surface,
It is possible to obtain a power conversion device which is excellent in cooling property and is easy to handle.

[Brief description of drawings]

FIG. 1 is a schematic power system diagram of a drive system of an electric vehicle using a power converter of the present invention.

FIG. 2 is a side view of the power conversion device.

FIG. 3 is a top view of FIG.

FIG. 4 is a state diagram in which an electrolytic capacitor is inserted into a cooling heat sink.

5 shows the cooling passage in the side view of FIG.

FIG. 6 is a cross-sectional view of the cooling heat sink of the present invention.

FIG. 7 is a plan view showing another embodiment of the electrolytic capacitor bus bar of the present invention.

[Explanation of symbols]

1 ... Battery, 2 ... Power converter, 3 ... AC electric motor, 4
… Electrolytic capacitors, 5… Power semiconductor devices (IGBT),
6 ... Cooling heat sink, 6a ... Capacitor insertion hole, 6
b ... Coolant passage, 9, 10 ... Closed loop bus bar, 11 ... Bus bar (+) (electrolytic capacitor to IGBT), 12 ... Bus bar
(-) (Electrolytic capacitor to IGBT), 16 ... Current sensor, R ... Snubber resistance.

Claims (10)

[Claims] 1. A power conversion device comprising an electrolytic capacitor for smoothing a voltage from a battery, and a power semiconductor element configured to control the AC motor by converting the voltage from the capacitor into electric power. A power conversion device comprising a cooling heat sink arranged to forcibly circulate a cooling liquid between the power semiconductor element and the power semiconductor element. 2. The power converter according to claim 1, wherein the cooling heat sink is an integral structure having an electrolytic capacitor mounting insertion hole in a central portion and a plurality of cooling liquid passages arranged outside thereof. 3. The power conversion device according to claim 2, wherein the cooling heat sink is formed in a polygonal shape, and the power semiconductor element is arranged and fixed on the outer side thereof. 4. The power conversion device according to claim 1, wherein terminals of the same polarity are concentrically arranged on one end face of the electrolytic capacitor as a single closed loop bus bar. 5. The power converter according to claim 3, wherein a plurality of power semiconductor elements are arranged on the same plane for each phase, and a snubber resistor is arranged between them. 6. The bus bar connecting the pole terminal of the electrolytic capacitor and the pole terminal of the power semiconductor element is formed in an L shape, and the bus bar of the same pole has a common shape. Power converter. 7. A power conversion device comprising an electrolytic capacitor for smoothing a voltage from a battery, and a power semiconductor element configured to control the AC motor by converting the voltage from the capacitor into electric power. And a power semiconductor element, a cooling heat sink having a polygonal shape, an insertion hole for mounting an electrolytic capacitor in the central portion, and a cooling liquid passage connected to a forced circulation passage is arranged. A power conversion device characterized in that a power semiconductor element is mounted on. 8. A power converter according to claim 7, wherein a plurality of cooling liquid passages are formed along the axial direction of the condenser, and are connected at both ends to an annular passage led to the forced circulation passage. . 9. The power converter according to claim 7, wherein the cooling heat sink is made of an aluminum material. 10. A power conversion device comprising an electrolytic capacitor for smoothing a voltage from a battery, and a power semiconductor element for converting the voltage from the capacitor into electric power to control an AC motor. Between the power semiconductor element and the power semiconductor element, a cooling heat sink having a hexagonal insertion hole for mounting an electrolytic capacitor in the center and a cooling liquid passage connected to the forced circulation passage, and a gap between the hexagonal surfaces. A power conversion device comprising a power semiconductor element arranged on a plane and connected to the electrolytic capacitor via a busbar, and a current sensor fixedly arranged on a symmetry plane of the power semiconductor element and connected to an electric motor. apparatus.