JP7675370B2 - Power Conversion Equipment - Google Patents

Description

The present invention relates to a power conversion device.

The following Patent Document 1 discloses a power conversion device in which the cooling pipes, which are the inlets and outlets for the cooling water, and the ventilation holes are at the same height.

JP 2016-92934 A

Taking into account conventional configurations, the present invention aims to provide a power conversion device with improved cooling performance in order to more efficiently cool electronic components within the device.

The power conversion device is a power conversion device that houses a power conversion module in a housing, and includes a heat generating element of the power conversion module, a cooling unit that cools the heat generating element, and an electronic component different from the heat generating element, and an air vent is formed in the housing below the cooling unit, and the electronic component is disposed in the space between the cooling unit and the air vent.

The present invention provides a power conversion device with improved cooling performance.

Diagram of power converter and motor An exploded view of the power converter of FIG. 1 is a cross-sectional view of a power converter according to an embodiment of the present invention; An exploded view of the current sensor of FIG.

The following describes an embodiment of the present invention with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some parts have been omitted or simplified as appropriate for clarity of explanation. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

(One embodiment of the present invention and overall configuration of the device)
Fig. 1(a) is a diagram of a power converter and a motor, and Fig. 1(b) is a diagram of the power converter and the motor separated from each other. Fig. 2 is an exploded view of the power converter of Fig. 1.

The power conversion device 1 is fixed to an external device such as a motor 4 with bolts. Note that the direction in which the power conversion device 1 in FIG. 2 is fixed to the motor 4 is the upward direction on the paper. A cooling pipe 2, a DC bus bar 8, and an AC bus bar 13 protrude from the outside of the power conversion device 1. The AC bus bar 13 is inserted into the motor 4 so as to be connected to the terminal block 4a of the motor 4, and the vicinity of the joint between the AC bus bar 13 and the motor 4 (terminal block 4a) is sealed with a sealing material 4b such as rubber to ensure airtightness.

The power conversion device 1 is equipped with a plurality of power conversion modules 5 with semiconductor elements built in the housing 10. The power conversion modules 5 are equipped with semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors), and DC power from a battery is conducted via a DC bus bar 8, and the DC power is converted to AC power by switching. The converted AC power is transmitted to an external device such as a motor 4 via an AC bus bar 13. The motor 4 drives a rotating body provided inside the motor 4 using the AC power from the power conversion device 1.

The control board 16 that controls the power conversion module 5 is fixed to a plate-shaped base plate 15. The capacitor element 6 that smoothes the ripple current generated by the switching of the semiconductor element is fixed by potting resin 7 that is filled inside the metal case housing 10.

The terminal portion of the power conversion module 5 is electrically connected to the control board 16 through the base plate 15. The control board 16 controls the switching of the power conversion module 5 according to instructions from an external higher-level control signal. The current output from the power conversion module 5 to the motor 4 is detected by a current sensor 14 arranged between the power conversion module 5 and the AC bus bar 13, and the detected value is transmitted to the control board 16.

The water channel cover 11 is joined to the housing 10 to form a refrigerant flow path that cools the power conversion module 5. The housing 10 is provided with a refrigerant inlet 2a and a refrigerant outlet 2b that are connected to this refrigerant flow path and introduce a refrigerant from the outside.

The aforementioned components housed in the housing 10 are fixed inside, and a cover 9 is fixed to the opening end face of the housing 10, which is a metal case, to make the inside of the housing 10 dust-proof. The housing 10 is provided with an air vent 3 into which a waterproof filter 12 is fitted. The waterproof filter 12 is made of a material that allows air to pass through but not water, preventing water from entering the power conversion device 1 and ensuring ventilation between the air inside and outside the power conversion device 1.

Figure 3 is a cross-sectional view of a power conversion device according to one embodiment of the present invention, where Figure 3(a) is an external view of the power conversion device from above, and Figure 3(b) is a cross-sectional view taken along line A-A in Figure 3(a).

In the power conversion device 1, the internal parts that generate heat due to the inherent resistance of the bus bars 8 and 13 during power conduction are controlled to within a guaranteed temperature range by the coolant introduced from the outside through the cooling pipes 2. In addition, the coolant flow path 2c shown in FIG. 3(b) mainly serves to cool the semiconductor elements of the power conversion module 5 that generate a large amount of heat.

However, the temperature inside the sealed power conversion device 1 varies depending on the location inside the device 1, and if high heat remains in an area where low heat-resistant electronic components such as the current sensor 14 are installed, this component may be adversely affected. For this reason, it is necessary to efficiently cool low heat-resistant electronic components such as the current sensor 14.

Therefore, in the present invention, the vent hole 3 blocked by the waterproof filter 12 described above is formed in the housing 10 below the refrigerant flow path 2c, which is the cooling section. Furthermore, a current sensor 14, which is an electronic component separate from the semiconductor element of the power conversion module 5, which is the heat generating element, is placed in the space between the refrigerant flow path 2c and the vent hole 3.

By doing this, air convection 17 is generated inside the housing 10 as shown by the arrows, and air is exhausted 17a through the air vent 3. By generating a flow of air that is exhausted from inside the housing 10 to the outside, the air inside the device 1 that has been cooled by the cooling water circulates, allowing the internal components and electronic components of the housing 10 to be efficiently cooled.

The present invention has been described using the current sensor 14 as an example of an electronic component other than a semiconductor element, which is a heat-generating element. However, the same method can be used to cool not only the current sensor 14 but also substrates that tend to generate heat, resistors and chips mounted on the substrate, and other components that need to be primarily cooled. The positional relationship between the refrigerant flow path 2c and the ventilation hole 3 can be set arbitrarily to determine which electronic component needs to be primarily cooled.

(Principle of the Invention)
In the upper part (upper part of the drawing) of the device 1 cooled by the cooling water, the density of the air is higher than the density of the air around the heat-generating components. This causes air convection in the device 1. In addition, the housing 10 has an air vent 3 that communicates with the outside air, located at a position away from the refrigerant flow path 2c and on the lower side. The internal air around the air vent 3 expands due to the heating of the heat-generating components, and the air of the convection 17 tries to go to the outside toward the air vent 3 in response to the flow discharged to the outside of the housing 10. This series of flows causes the air cooled by the refrigerant flow path 2c to spread throughout the power conversion device 1. This allows electronic components with low heat resistance that need to be cooled, such as the current sensor 14, to be efficiently cooled.

When the refrigerant flow path 2c, which is the cooling section, is located far from the housing wall on which the ventilation holes 3 are formed, based on the center of the housing 10, the air cooled by the refrigerant flow path 2c can be spread throughout the power conversion device as described above, and the entire space of the housing 10 can be cooled evenly. Also, when the refrigerant flow path 2c is located close to the housing wall on which the ventilation holes 3 are formed, based on the center of the housing 10, the cooling effect is increased for low-heat-resistant electronic components located between them. Note that when the housing 10 is divided into an upper space and a lower space, the refrigerant flow path 2c is located on the upper space side, and the ventilation holes 3 are formed on the lower space side.

In this way, by arbitrarily setting the position of the cooling unit to match the position of the vent 3, it is possible to control the convection and determine the area to be actively cooled. Note that it is also possible to use a method in which the area to be actively cooled is determined by arbitrarily setting the position of the vent 3 relative to the cooling unit.

Figure 4 is an exploded view of the current sensor in Figure 3.

The current sensor 14 has a magnetic core 18 with a gap formed in a portion thereof housed in an overmolded case 23 and fixed by a sensor cover 22. The circuit board 20 is mounted so that the detection element 19 is positioned in a gap in the magnetic core 18, and is fixed to the overmolded case 23 by a base 21.

In such a current sensor 14, the circuit board 20 on which the detection element 19 is mounted can be positioned closer to the refrigerant flow path 2c described above, allowing the circuit board 20 to dissipate heat efficiently. Note that the same effect can be obtained by placing not only the current sensor 14 but also other components with low heat resistance closer to the refrigerant flow path 2c.

The embodiment of the present invention described above provides the following effects:

(1) The power conversion device 1 houses a power conversion module 5 in a housing 10, and includes a heat generating element of the power conversion module 5, a cooling unit 2 that cools the heat generating element, and electronic components different from the heat generating element. In the housing 10, an air vent 3 is formed below the cooling unit 2, and the electronic components are disposed in the space between the cooling unit 2 and the air vent 3. In this way, it is possible to provide a power conversion device 1 with improved cooling performance.

(2) The electronic component is a current sensor 14 that detects the output current of the power conversion module 5. This allows the reliability of the current sensor 14 to be maintained.

(3) The current sensor 14 has a magnetic core 18 with a gap formed in a portion thereof, and a circuit board 20 on which a detection element 19 is mounted so as to be placed in the gap. When the current sensor 14 is placed inside the housing 10, the circuit board 20 side is placed in a position close to the cooling unit 2. This allows the reliability of the current sensor 14 to be maintained.

(4) The cooling unit 2 is positioned far from the housing wall in which the air vent 3 is formed, with respect to the center of the housing 10. In this way, the convection current 17 of the air cooled by the cooling unit 2 spreads throughout the device 1, allowing the internal electronic components to be evenly cooled.

(5) The cooling unit 2 is positioned close to the housing wall in which the ventilation holes 3 are formed, with the center of the housing 10 as the reference point. This allows efficient cooling of electronic components that need to be cooled in a concentrated manner.

(6) When the space inside the housing 10 is divided into an upper space and a lower space, the cooling unit 2 is placed in the upper space side, and the air vents 3 are formed in the lower space side. In this way, the convection current 17 of the air cooled by the cooling unit 2 spreads throughout the device 1, allowing the internal electronic components to be evenly cooled.

The present invention is not limited to the above-described embodiment, and various modifications and other configurations can be combined without departing from the spirit of the invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiment, and also includes those in which some of the configurations have been omitted.

REFERENCE SIGNS LIST 1 Power conversion device 2 Cooling pipe 2a Refrigerant inlet 2b Refrigerant outlet 2c Refrigerant flow path 3 Vent 4 Motor 4a Terminal block 4b Sealing material 5 Power conversion module 6 Capacitor element 7 Potting resin 8 DC bus bar 9 Cover 10 Housing 11 Water channel cover 12 Waterproof filter 13 AC bus bar 14 Current sensor 15 Base plate 16 Control board 17 Air convection 17a Air exhaust 18 Magnetic core 19 Detection element 20 Circuit board 21 Base 22 Sensor cover 23 Overmolded case

Claims (3)

A power conversion device having a power conversion module housed in a housing,
The power conversion module includes a heat generating element, a cooling unit that cools the heat generating element, and an electronic component that is different from the heat generating element,
When the space inside the housing is divided into an upper space and a lower space, the cooling unit is disposed on the upper space side, and an air vent is formed on the lower space side to ensure ventilation between the air inside the housing and the air outside the housing,
the electronic component is disposed in a space in the housing between the cooling unit and the ventilation hole , and is disposed closer to the ventilation hole than other electronic components;
the electronic component is a current sensor that detects an output current of the power conversion module,
The current sensor includes a magnetic core having a gap formed in a portion thereof, and a circuit board on which a detection element is mounted so as to be disposed in the gap;
In the current sensor, the circuit board side faces the cooling unit and is located closer to the cooling unit than the magnetic core.
Power conversion equipment. The power conversion device according to claim 1,
The cooling unit is disposed at a position far from a wall of the housing in which the air hole is formed, with respect to a center of the housing. The power conversion device according to claim 1,
The cooling unit is disposed at a position close to a wall of the housing in which the ventilation hole is formed, with respect to a center of the housing.