Switching module including a snubber circuit connected in parallel to a series-connected unit of flowing restriction elements
A switching module includes a series-connected unit of a first flowing restriction element and a second flowing restriction element, the first flowing restriction element having an opening and closing function of opening and closing a flowing path of current, and the second flowing restriction element having at least one of a rectifying function of restricting the direction in which current flows and the opening and closing function, and a snubber circuit connected to the series-connected unit in parallel. A first wiring line connecting between the first flowing restriction element and the snubber circuit, a second wiring line connecting between the second flowing restriction element and the snubber circuit, a third wiring line connecting between the first flowing restriction element and the second flowing restriction element, the first flowing restriction element, the second flowing restriction element, and the snubber circuit are formed substantially integrally with each other by using an insulator.
1. A switching module, comprising:
a series-connected unit of a low-potential-side flowing restriction element and a high-potential-side flowing restriction element, the low-potential-side flowing restriction element having an opening and closing function of opening and closing a flowing path of current, and the high-potential-side flowing restriction element having at least one of a rectifying function of restricting the direction in which current flows and the opening and closing function; and
a snubber circuit connected to the series-connected unit in parallel, wherein
a low-potential-side wiring line connecting between the low-potential-side flowing restriction element and the snubber circuit, a high-potential-side wiring line connecting between the high-potential-side flowing restriction element and the snubber circuit, an intermediate wiring line connecting between the low-potential-side flowing restriction element and the high-potential-side flowing restriction element, the low-potential-side flowing restriction element, the high-potential-side flowing restriction element, and the snubber circuit are formed substantially integrally with each other by using a multilayer board,
a low-potential-side semiconductor chip configuring the low-potential-side flowing restriction element and a high-potential-side semiconductor chip configuring the high-potential-side flowing restriction element are arranged so as to be opposed to each other,
the low-potential-side wiring line is formed on a side of one of a pair of opposed surfaces of the low-potential-side semiconductor chip, the surfaces being adjacent to another surface of the low-potential-side semiconductor chip,
the high potential-side wiring line is formed on a side of one of a pair of opposed surfaces of the high-potential-side semiconductor chip, the surfaces being adjacent to another surface of the high-potential-side semiconductor chip, the another surface of the low-potential-side semiconductor chip and the another surface of the high-potential-side semiconductor chip being opposed to each other,
the intermediate wiring line is formed on a side of the other of the pair of the surfaces of the low-potential-side semiconductor chip and on a side of the other of the pair of the surfaces of the high-potential-side semiconductor chip,
the low-potential-side semiconductor chip configuring the low-potential-side flowing restriction element and the high-potential-side semiconductor chip configuring the high-potential-side flowing restriction element are formed in the same layer of the multilayer board,
a first current path between the snubber circuit and the high-potential-side semiconductor chip is opposed to a second current path between the high-potential-side semiconductor chip and the intermediate wiring line, and the directions in which currents flow in the first and second current paths are opposite to each other, and
a third current path between the snubber circuit and the low-potential-side semiconductor chip is opposed to a fourth current path between the low-potential-side semiconductor chip and the intermediate wiring line, and the directions in which currents flow the third and fourth current paths are opposite to each other.
2. The switching module according to claim 1 , wherein the low-potential-side semiconductor chip configuring the low-potential-side flowing restriction element and the high-potential-side semiconductor chip configuring the high-potential-side flowing restriction element are vertical devices,
the opposed surfaces of the low-potential-side semiconductor chip are both ends of a flowing path of current of the low-potential-side flowing restriction element, and
the opposed surfaces of the high-potential-side semiconductor chip are both ends of a flowing path of current of the high-potential-side flowing restriction element.
3. The switching module according to claim 1 , wherein
each of the low-potential-side flowing restriction element and the high-potential-side flowing restriction element includes a switching element and a free wheel diode connected to the switching element in anti-parallel.
4. The switching module according to claim 2 , wherein
the low-potential-side wiring line and the high-potential-side wiring line have surface areas larger than areas of the semiconductor chips.
5. The switching module according to claim 2 , wherein
the intermediate wiring line has a surface area larger than the sum of an area of the low-potential-side semiconductor chip configuring the low-potential-side flowing restriction element and an area of the high-potential-side semiconductor chip configuring the high-potential-side flowing restriction element.
6. The switching module according to claim 2 , wherein
the heights of the low-potential-side wiring line and the high-potential-side wiring line are equal to or more than that of an element configuring the snubber circuit.
7. The switching module according to claim 2 , wherein
the low-potential-side wiring line and the high-potential-side wiring line are covered with an insulating film, and
a heat sink is provided on the back side of a surface of the insulating film, the surface being opposed to the low-potential-side and the high-potential-side wiring lines.
8. The switching module according to claim 2 , wherein
the intermediate wiring line is covered with an insulating film, and
a heat sink is provided on the back side of a surface of the insulating film, the surface being opposed to the intermediate wiring line.
9. The switching module according to claim 2 , wherein
the high-potential-side wiring line and the low-potential-side wiring line are respectively connected to a high-potential-side bus bar and a low-potential-side bus bar, and the intermediate wiring line is connected to a bus bar on the side of a connecting point, and
a first magnetic flux generated by a current flowing through a loop circuit configured by the snubber circuit, the low-potential-side flowing restriction element, and the high-potential-side flowing restriction element, a second magnetic flux generated by a current flowing between the low-potential-side wiring line and the intermediate wiring line, and a third magnetic flux generated by a current flowing between the high-potential-side wiring line and the intermediate wiring line are not parallel to each other.
10. The switching module according to claim 9 , wherein
the low-potential-side flowing restriction element includes a switching control terminal into which an instruction for opening and closing the flowing path is inputted, and
the direction in which the low-potential-side wiring line, the high-potential-side wiring line, and the intermediate wiring line extend to the outside of the insulator and the direction in which a line connected to the switching control terminal extends to the outside of the insulator form an obtuse angle.
11. The switching module according to claim 10 , wherein
the low-potential-side flowing restriction element further includes a reference potential terminal for determining a reference potential of operation thereof, and
the line connected to the switching control terminal and a line connected to the reference potential terminal are formed in the same layer.
12. The switching module according to claim 1 , wherein
the low-potential-side flowing restriction element includes a switching control terminal into which an instruction for opening and closing the flowing path is inputted, and
a line connected to the switching control terminal includes a line of the multilayer board.
13. The switching module according to claim 1 , wherein
the low-potential-side wiring line, the high-potential-side wiring line, and the intermediate wiring line include a line of the multilayer board.
14. The switching module according to claim 1 , wherein
a side surface of the multilayer board is covered with molding material.
15. The switching module according to claim 1 , wherein
the snubber circuit includes a capacitor connected to the series-connected unit in parallel, and a rectifying unit configuring a charging path of the capacitor, and
the rectifying unit is connected to a discharging path of the capacitor in parallel, the capacitor having impedance larger than that of the charging path.
16. The switching module according to claim 15 , wherein
in the rectifying unit, on-resistance is set by which an actual charging rate becomes larger than a charging rate of the capacitor determined by a resonance frequency according to parasitic inductance of a bus bar connected to the low-potential-side wiring line and capacitance of the capacitor.