JPH02161761A - Semiconductor device for electric power - Google Patents

Abstract

PURPOSE:To prevent unbalance of current among elements when semiconductor units are connected between bus bars in series, by constructing each of the bus bars so as to have different thicknesses or widths of a specific ratio, the difference of the thicknesses or widths being represented by arithmetic progression. CONSTITUTION:A bus bar 12A to which terminals 5A1, 5B1 and 5C1 are connected has a larger thickness T1 on the lefthand side close to the arrow IN and a smaller thickness T2 on the righthand side, as viewed on the drawing. Ratio of the thickness T1 to the thickness T2 is equal to a ratio of a number of semiconductor elements 1A through 1C connected in series-1:1, and T1=2T2 in this case. The boundary of the section having the thickness T1 and the section having T2 corresponds to the righthand end of a terminal plate 5B2 located at the center, while terminal plates are spaced by an equal distance l. Similarly, a bus bar 12B to which terminal plates 5A2, 5B2 and 5C2 are connected has similar configurations to those of the bus bar 12A while the terminal plates are spaced by the same distance l as those on the bus bar 12A. According to such arrangement, current paths in the elements 1A through 1C have equal resistances and, therefore, unbalance of current among the elements due to voltage drop in the bus bars 12A, 12B can be prevented effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a power semiconductor device in which semiconductor elements are connected in parallel.

(Prior Art) In FIG. 4 showing an example of a conventional power semiconductor device,
On the opposing faces of the steel buses <-2A and 2B made of strip material, an L-shaped terminal plate 5A, 581° 5C1 made of steel plate is attached to the bus bar 2A, and a terminal plate 5A2.5B2.5C2 is also attached to the bus bar 2A.
are mounted with bolts (not shown) facing the bus bar 2B at equal intervals, and the terminal plates 5A, 5A2, 5B and 5
Between the opposing surfaces of B2.5C□ and 502, there is a power semiconductor element (hereinafter referred to as element) IA such as a thyristor.
, IB, and Ic are installed. Furthermore, the terminal board 5A
.

5A2, 5B and 5B, 5C and 5C2 have cooling fins 6 made of aluminum installed on the non-opposed surfaces of terminal plates 580 and 582. An insulating plate 7 is sandwiched between the cooling fins 6 attached between the terminal plates 5B and 502, and the whole is assembled into one unit.

By the way, in a power semiconductor device in which multiple elements are connected in parallel, not only do the characteristics such as on-voltage and forward voltage drop of each element be the same, but also the characteristics of the main circuit to which each element is connected are the same. It is necessary to prevent current imbalance due to impedance differences. Conventionally, resistors and anode reactors were connected in series with each element, or current balancing reactors were used, but this not only wastes power, but also increases the number of connection bus bars and mounting locations, making it complicated and large. Become.

(Problem to be solved by the invention) Therefore, a method of using bus bars that connect each element with the same length and resistance value and with the same characteristics of each element can be considered, but even then, the inner The current flowing through the element decreases.

That is, in FIG. 5 showing the connection diagram of FIG. 4, now,
Assuming that the current i flowing through each element is equal, the voltage drop occurring in the current path between AF of each element is as follows: In element IA...VrA=Vr+3r-i+
r'・j... (1) In element IB...
VFB=VF+4r-i+r'・i...■For element IC, 1'%c''VF+3r-i+r'・i
-...(3) However, VF = Forward voltage drop of each element r: Resistance of the bus bar between the connecting terminals r': The resistance of the connecting terminal itself, and the voltage drop (VFB) of the current path of element IB is higher than the other is also greatly needed.

Note: Actually, since vr of each element is selected to be equal, the current of element IB is small and unbalanced.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain a small, efficient power semiconductor device with good current balance.

[Structure of the invention]

(Means and Effects for Solving the Problems) The present invention provides a power semiconductor device comprising a semiconductor unit in which at least three semiconductor elements of the same rating are connected in parallel at equal intervals between a pair of rectangular cross-section bus bars. , the width or thickness ratio between the side connected to the outside and the other side of each bus bar is
By setting the number of semiconductor elements connected in parallel to -1:1 and making the width or thickness between them the difference in an arithmetic progression, the current flowing through each semiconductor element is made equal, resulting in efficient and compact power. It is a semiconductor device for

(Example) An example of the power semiconductor device of the present invention will be described below with reference to the drawings. However, parts that overlap with Figures 4 and 5 are omitted.

In Fig. 1, the thickness of the bus bar 12A on the side to which terminals 5A, 5B, and 5C are connected is thicker on the left end (not shown) or on the side connected to the external bus bar (arrow IN) and thinner on the right end. , the left side thickness T1 and the right end thickness T,
The ratio is Ti=27. It becomes. The boundary coincides with the right end of the central terminal plate 5B1, and the mounting intervals Q of the terminal plates are equal.

Similarly, the bus bar 12B to which the terminal boards 5A2.5B, , 5C2 are connected has the same shape as the bus bar 12A, and the thickness T2 of the left half is half the thickness T of the right half and the right end connection part.
Each terminal board is connected at the same interval Q as the bus bar 12A side.

As a result, on the bus bar 12A side, the resistance value between AB is BC
On the bus bar 12B side, the resistance value between EF and DE is one half of that between DE, so the resistance of the current path of each element can be made equal, and the resistance of the elements due to the voltage drop of the bus bar can be made equal. Current imbalance can be prevented.

That is, in FIG. 2 showing the connection diagram of the power semiconductor device configured as shown in FIG. 1, if an equal current 1 flows through each element, the voltage drop (VF) that occurs between the current paths between the AFs of each element is is element A...VFA=V
F+4r□・i+r'・i・・・・・・(to) Element IB
So...VFn=VF+4r□・i+r'・i
・・・・・・■ Even in element IC, 1%rc=t/F+4r,
・i+r′ ・i−(69 However, r□: is the minimum resistance of the bus bar between the connection terminals.

As a result, there is no need to connect resistors, anode reactors, or current balancing reactors to each element, and there is no need for space for them, resulting in a power semiconductor device that is highly efficient, compact, lightweight, and capable of preventing current imbalance between each element. Become.

In the above embodiment, the left and right cross-sectional areas of the bus bars 12A and 1211 are changed in the thickness direction, but they may also be changed in the width direction, which has the advantage of being suitable for wide terminals such as the terminal Fi5A1.

Also, even when the number of elements is 4 or more, the resistance value from the connection end with the outside is defined as rl : r2 : · as in the above embodiment.
...: r(n-2): r(n-1)=1:2
:...: (n-2) : By selecting in order the difference between (n-1) and the arithmetic progression, unbalanced currents in each element can be prevented and efficient, compact and lightweight power semiconductor devices can be created. Obtainable.

In the above embodiment, the width or thickness of the pair of busbars is narrowed stepwise, but the busbars 24A and 24B may be made trapezoidal and continuously narrowed as shown in FIG. When this happens, it can be processed using a shearing machine, which has the advantage of making it easier to manufacture.

〔Effect of the invention〕

As described above, according to the present invention, in a power semiconductor device configured with a semiconductor unit in which at least three or more semiconductor elements of the same rating are connected in parallel at equal intervals between a pair of rectangular cross-section bus bars, each bus bar is connected to the outside. The width or thickness ratio between the exposed side and the other end is set to be the number of semiconductor elements connected in parallel - 1:1.

Since the difference in width or thickness between them is treated as a difference in arithmetic progression, the current flowing through each semiconductor element is made equal, so that a small and efficient power semiconductor device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the power semiconductor device of the present invention, FIG. 2 is a connection diagram of FIG. 1, and FIG. 3 is a diagram showing another embodiment of the power semiconductor device of the present invention. FIG. 4 is a diagram showing a conventional power semiconductor device, and FIG. 5 is a connection diagram of FIG. 4. IA, IB, ], C...Power semiconductor element 5A1.5
A, , 5B1.5B2.5C engineering, 5C2...Terminal board 12A, 12B...Bus bar (8733) Agent Patent attorney Yoshiaki Inomata (1 idiot) Figure 1 Figure 8 Figure 2

Claims (1)

[Scope of Claims] A power semiconductor device constituted by a unit in which at least three semiconductor elements of the same rating are connected in parallel at equal intervals between a pair of bus bars having a rectangular cross section, the power semiconductor device being connected to the outside of the bus bar. The width or thickness ratio between one side and the other side is set to the total number of the semiconductor elements - 1:1, and the difference in the width or thickness of the element connection part between them is set as the difference in an arithmetic progression. Power semiconductor devices.