High power density DC-AC power inverter

A high power density DC-AC power inverter includes a casing corresponding to a rack. The casing has air inlets and air outlets arranged in a honeycomb shape and a fan unit. The casing is provided with two choke coils and a heat sink therein. The heat sink includes fins facing downward. A plurality of power elements are laterally provided on top of the heat sink. The heat generated from the power elements can be conducted to the fins of the heat sink quickly. The fan unit guides the outside air to the heat sink and the choke coils through the air inlets, and the heat is smoothly expelled out of the casing through the air outlets of the casing. The power inverter in a high density configuration still has a good heat dissipation effect.

FIELD OF THE INVENTION

The present invention relates to the configuration of a power inverter, and more particularly to a high power density DC-AC power inverter.

BACKGROUND OF THE INVENTION

Various power inverters have been widely used in electronic circuits (such as power supplies, computers, household appliances, nuclear magnetic resonance gradient amplifiers, UPS uninterruptible power systems, solar inverters, converters, power amplifiers for a vibration test, frequency converter of 400 Hz, 800 Hz, 1200 Hz, etc.) to provide a stable constant voltage or constant current. Its function is that an input power type is converted into a required load power type. In general, a power inverter is composed of a power switch component (such as a power transistor, a power diode, etc.), an electrical energy storage, and a filter component (such as an inductor, a capacitor, a transformer, a choke coil, etc.), and a detection and control component.

Thereby, the voltage or current is adjusted (switched and rectified) by the detection and control component to control the power switch component. The electric energy storage and the filter component provide the required filtering and temporary electrical energy for converting the electric energy. However, during the power conversion, the power inverter converts part of the energy supplied from the power supply into heat energy. The heat energy is concentrated in the power transistor and the choke coil of the power inverter.

The demand for power inverters used for industrial and server applications is extremely large. The power inverters are mounted to a chassis through a rack. A general business gathers power inverters and servers in a computer room to facilitate the management. The power inverters and the servers are running all day long. Therefore, the heat dissipation of the power inverters is particularly important.

For the convenience of management and space saving, the casing for the rack-type power inverter usually adopts a common industrial standard, its width is fixed at 19 inches, height in U units (1 U=1.75 inches=44.45 mm). The standard casings are usually 1 U, 2 U, 3 U, and others. In general, at the same power, the power inverter composed of a power switch component, a power storage, and a filter component, and a detection and control component needs better heat dissipation conditions, so it is necessary to use a larger casing, such as a casing of 3 U or more.

However, in order to reduce the size of the casing, a casing of 2 U or less is developed accordingly. But its configuration design causes poor heat dissipation. The reason is that the power inverter has a plurality of choke coils and a plurality of power transistors. The choke coils are often horizontally arranged in the limited space, so the heat is concentrated at the bottoms of the choke coils. The power transistors and other electronic components are generally vertically arranged on the circuit board, which shields the wind blowing of the fan and cannot provide a smooth heat dissipation path. As a result, the heat is concentrated at the power transistors and the choke coils of the power inverter. The power inverter may stop running or fail or be damaged due to overheating.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a high power density DC-AC power inverter. The heat generated from power elements and choke coils inside the power inverter can be conducted to the outside through a fan unit, achieving rapid heat dissipation.

In order to achieve the aforesaid object, the high power density DC-AC power inverter of the present invention is mounted to a rack. The high power density DC-AC power inverter comprises a casing, a fan unit, a heat sink, a plurality of power elements, and a circuit board module. The casing corresponds in size to the rack. A front side of the casing is formed with a plurality of air inlets. A rear side of the casing is formed with a plurality of air outlets. The fan unit is disposed at one side of the casing for guiding air to enter the casing via the air inlets and discharge to the outside via the air outlets in a guide direction. The heat sink is laterally disposed in the casing. The heat sink includes a plurality of spaced fins. The fins each have a long side parallel to the guide direction. The power elements each have a heat dissipation surface. The heat dissipation surfaces of the power elements are laterally attached to the heat sink. The circuit board module is laterally disposed above the heat sink and electrically connected with the power elements.

When the power inverter is actuated, the power elements generate heat and the heat is conducted to the fins of the heat sink via the shortest route. The fan unit guides the outside cold air into the casing via the air inlets of the casing to pass through the fins of the heat sink for heat dissipation, and the heat is smoothly expelled out of the casing via the air outlets of the casing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1,FIG. 2andFIG. 3illustrate perspective views and an exploded view of a high power density DC-AC power inverter in accordance with a preferred embodiment of the present invention. The power inverter may be mounted to a rack. The power inverter comprises a casing10, a fan unit20, a heat sink30, a plurality of power elements40, a circuit board module50, a wind scooper60, and a choke coil module70.

The casing10corresponds in size to the rack. Front and rear sides of the casing10are provided with a front panel11and a rear panel12, respectively. The bottom of the casing10is provided with a bottom plate13. The front panel11is formed with a plurality of air inlets111. The rear panel12is formed with a plurality of air outlets121. The air inlets111and the air outlets121are arranged in a honeycomb shape. A lower edge of the rear panel12is bent inwardly to form a connecting portion122. The connecting portion122is overlapped with the bottom plate13of the casing10, so that a portion of the air outlets121is located at the junction of the rear panel12and the bottom plate13to reduce the accumulation of dust.

The fan unit20is disposed at one side of the casing10. The fan unit20is disposed in the casing10close to the air inlets111for guiding the outside cold air to enter the casing10via the air inlets111and then discharge to the outside via the air outlets121, so that the air inlets111and the air outlets121form a guide direction for heat dissipation.

The heat sink30is made of a heat-dissipating aluminum material, and is disposed in the casing10. The heat sink30is located adjacent to the air inlets111. The heat sink30includes a plurality of spaced fins31. The fins31face downward. The fins31each have a long side parallel to the guide direction.

Referring toFIG. 4, in this embodiment, the power elements40are metal oxide semiconductor field effect transistors (MOSFETs). The power elements40are located on top of the heat sink30. Each power element40has a heat dissipation surface41which is laterally attached to a top surface of the heat sink30, so that the heat generated from the power element40can be quickly conducted to the fins31of the heat sink30.

The circuit board module50, as shown inFIG. 5, is laterally disposed above the heat sink30and is electrically connected with the power elements40. The circuit board module50includes a power element circuit board51, a drive board52, and a control board53. The power element circuit board51, the drive board52and the control board53are superposed from each other from bottom to top, and are electrically connected through longitudinal slots to form the shortest distance so as to reduce the noise and ringing effect.

The wind scooper60, referring toFIG. 6, is disposed in the casing10. The wind scooper60is located between the fan unit20and the heat sink30. The wind scooper60has a guide entrance61adjacent to the fan unit20and a guide exit62adjacent to the heat sink30for guiding the outside air from the air inlets11to the fins31of the heat sink30. The wind scooper60is further provided with a plurality of guide holes63. The guide holes63are located above the heat sink30and adjacent to the power elements40. The guide entrance61of the wind scooper60is greater than the guide exit62and the guide holes63, and the guide exit62is greater than the guide holes63.

The choke coil module70, referring toFIG. 7, is disposed in the casing10. The choke coil module70includes a retainer71. The retainer71includes an upper plate711and a lower plate712which are laterally disposed. The lower plate712is fixed to the bottom plate13of the casing10. The upper plate711is located above the lower plate712, and is fixedly connected to the lower plate712through a plurality of longitudinal locking rods713, so that the retainer71is formed with an accommodation space between the upper plate711and the lower plate712. The upper plate711and the lower plate712have two slots7111,7121, respectively. The choke coil module70includes two choke coils72in the accommodation space of the retainer71. The choke coils72are disposed in the accommodation space of the retainer71in a staggered manner and slant from bottom to top toward the rear side of the casing10. Top portions and bottom portions of the choke coils72protrude out of and lean against the slots7111,7121of the upper plate711and the lower plate712, respectively.

Referring toFIG. 5andFIG. 7, when the power inverter is actuated, the power elements40and the choke coil module70generate heat and the heat is conducted to the fins31of the heat sink30. In addition, the choke coils72generate heat and the heat is conducted to the surroundings of the choke coils72. Meanwhile, the fan unit20guides the outside cold air to enter the casing10via the air inlets111of the casing10. Through the guide entrance62and the guide exit63of the wind scooper60, the outside cold air is guided to the fins31of the heat sink30and the choke coils72for heat dissipation, and the heat is expelled out of the casing10via the air outlets121of the casing10to achieve rapid heat dissipation.

Referring toFIG. 4andFIG. 5, the heat dissipation surfaces41of the power elements40are laterally attached to the heat sink30. When the power elements40generate heat, the heat can be easily conducted through the respective heat dissipation surfaces41to the heat sink30. The fins31are spaced apart from each other, and the fins31each have a long side. The long sides of the fins31are parallel to the guide direction, and a guide passage is defined between every two of the fins31. The wind generated by the fan unit20can easily pass through the fins31for heat dissipation without blocking the route of wind blowing.

Referring toFIG. 6, the guide entrance61of the wind scooper60is greater than the guide exit62and the guide holes63, and the guide exit62is greater than the guide holes63for controlling the air blown by the wind. The majority of the wind is concentrated at the guide exit62of the wind scooper60for the heat dissipation of the fins31of the heat sink30. The guide exit63of the wind scooper60is above the heat sink30so that a small portion of the wind can be blown to the circuit board module50above the heat sink30for heat dissipation.

Referring toFIG. 7, the slots7111,7121of the choke coil module70are adapted to engage with the top portions and the bottom portions of the choke coils72so that the choke coils72are secured stably. Through the slots7111,7121, the choke coils20can be easily arranged obliquely from bottom to top. The choke coils72slant from bottom to top toward the air outlets121. The wind blown by the fan unit20passes through the slots7111of the upper plate711to radiate the heat at the bottoms of the choke coils72, such that the heat won't be accumulated at the bottoms of the choke coils72and the power inverter won't fail due to overheating.

It is to be noted that only the front panel11and the rear panel12of the casing10are formed with the air inlets111and the air outlets121. There is no need for the upper and lower sides as well as left and right sides of the casing10to be formed with vents, so the casing10is more suitable to be mounted to the rack.

The features and expected effects of the present invention are described below.

The fan unit20, the heat sink30, the power elements40, the circuit board module50, and the choke coil module70in the casing10are suitably configured. When the power inverter is actuated, the heat generated from the power elements40can be conducted to the fins31of the heat sink30via the shortest route. Through the fan unit20, the outside air is guided through the air inlets111of the casing10to enter the casing10, so that the heat from the heat sink30and the choke coils72is discharged to the outside through the air outlets121of the casing10to achieve rapid heat dissipation. The present invention can be used in a smaller casing with a 2 U height to provide excellent heat dissipation. That is, in the same casing, the present invention is able to output greater power, compared to the traditional power inverter.