JPH04229079A - Parallel connecting method for semiconductor, switch circuit and inverter - Google Patents

Abstract

PURPOSE:To provide a simple and compact switch circuit and inverter using a method of connection for allowing even currents to flow through parallel semiconductor switches. CONSTITUTION:When connecting three in parallel, parallel connecting conductors 6 and 7 of anode-to-anode terminals and cathode-to-cathode terminals of a switch element as well as the connecting points 61 and 71 of feeding conductors 8 and 9 from a power supply 1 and a load 2 are mounted almost at the middle between the first and second switch elements 41 and 42. The feeding conductors 8 and 9 are lead out almost in parallel to parallel connecting conductors 61 and 62 of the second and third switch elements 42 and 43, thereby compensating the difference in self-inductance with mutual inductance. By aggressively utilizing the mutual inductance action, the parallel configuration can be simplified and the shape can be made smaller, thereby improving the utilization factor of switch elements or reliability, reducing assembly costs for the apparatus and making the size more compact.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for connecting semiconductor switching devices in parallel, and in particular, a parallel connection suitable for equalizing the shared current during transients of each parallel semiconductor switching device, simplifying the configuration, and reducing the size of the device. The present invention relates to a method, a switch circuit and an inverter suitable for simplifying the structure and reducing the size.

0002

[Prior art] Semiconductor switch elements (IGBT, GTO
, bipolar transistors, etc.), so when a larger current capacity is required, semiconductor switch elements (hereinafter referred to as switch elements) are connected in parallel. When connecting switch elements in parallel, it is important to configure the switch elements so that the shared currents of the parallel-connected switch elements are equal.

The shared current of each switch element connected in parallel is determined by the characteristics of each switch element and the difference in wiring for parallel connection. Recently, the manufacturing technology of switch elements has improved, and it has become relatively easy to select switch elements with uniform characteristics. For this reason, by configuring the wiring for each parallel connection to have a small difference, it has become possible to directly connect in parallel without using a current balancer, etc., which was commonly used in the past (Japanese Patent Application Laid-Open No. 102883/1983, (Japanese Unexamined Patent Publication No. 160069/1982). In direct parallel connection, it is important to configure the parallel connection wiring to minimize the difference in inductance.
Proposals such as Publication No. 75 have been made.

0004

The key point of the above-mentioned prior art is that the self-inductance of the parallel wirings is made equal while avoiding mutual induction between the wirings. This method is suitable when two switch elements are connected in parallel. However, as the number of parallel switch elements increases, parallel wiring becomes considerably difficult. For example, when four devices are connected in parallel, the configuration will be as shown in FIG. 6. If two wires are connected in parallel and then connected in parallel, and the wires are separated to avoid mutual induction between the wires, the problem arises that the configuration of the parallel connection becomes complicated and large. .

Another method is to simplify the configuration of parallel connection of switch elements by increasing the allowable value of the shared current unbalance rate. However, in order to ensure reliability, it is necessary to further increase the number of switch elements in parallel, resulting in a problem that the size becomes larger.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a parallel connection method suitable for equalizing the shared current of each switch element connected in parallel, simplifying the configuration, and reducing the size of the device; An object of the present invention is to provide a suitable switch circuit and inverter.

[0007]

[Means for Solving the Problems] In order to achieve the above object, we have simplified the parallel connection configuration, canceling out the difference in self-inductance of the wiring by mutual inductance between the wiring conductors, and improving the parallel connection. We have found a parallel wiring configuration in which the shared currents of each switching element are approximately equal.

For example, when n pieces are connected in parallel, the connection point between the parallel connection conductor A of the anode terminals and the cathode terminals of the switch elements and the power supply conductor B from the power supply and load is set to approximately the point between the first and second switch elements. Provided in the middle. and feed conductor B
, the parallel connection conductor A of the second to nth switch elements
Pull it out almost parallel to the In this case, the distance W between the parallel-connected conductor A and the substantially parallel power supply conductor B is set to about 70 mm or less in order to induce mutual induction therebetween.

[0009] Then, a switch circuit or an inverter device is constructed using such a method of connecting switch elements in parallel.

0010

According to the above structure, the self-inductance of the parallel-connected conductor A with respect to the connection point of the power supply conductor B is the largest in the n-th switch, and is almost the same in the first and second switches. The currents of the third to nth switch elements also flow through the parallel connection conductor A between the connection point of the power supply conductor B and the second semiconductor switch element. Therefore, when this parallel switch element turns on and turns off, the voltage generated in the self-inductance of the parallel-connected conductor A is the largest for the n-th switch element, and the voltage generated in the self-inductance of the parallel-connected conductor A is the largest for the The switch element is the smallest. On the other hand, mutual induction acts between the parallel-connected conductors A and the feed conductor B of the second to n-th switch elements, and the mutual inductance of the parallel-connected conductors A of the second to n-th switch elements It works to equivalently reduce self-inductance. The magnitude of the mutual inductance can be achieved by varying the spacing between the feed conductor B and the parallel connection conductor A. That is, the sum of self-inductance and mutual inductance acting on the second to nth parallel-connected conductors A can be varied.

[0011] Equalizing the shared currents is to make the voltages generated in the parallel-connected conductors A from the connection point of the parallel-connected conductors A to the anode and cathode terminals of each switch element almost equal. The structure allows this to be easily achieved by utilizing mutual induction. Since the distance between the parallel-connected conductor A and the power supply conductor B is much narrower than in the above-mentioned conventional technology in order to utilize the mutual induction effect more actively, it is possible to simultaneously simplify the parallel-connected configuration and reduce the size.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to drawings of embodiments.

FIG. 1 shows an assembly diagram of a parallel connection configuration according to an embodiment of the present invention. FIG. 1 is an example of a switch circuit in which three module-type switch elements are connected in parallel. Further, a sectional view taken along the line AA in FIG. 1 is shown in FIG. 1 and 2, 1 is a DC power supply, 2 is a load, 3 is a diode, 41 to
43 is a module type switch element, and 51 to 53 are wiring for control signals. The anode terminal and cathode terminal of the switch element are connected by an anode terminal parallel connection conductor 6 and a cathode terminal parallel connection conductor 7, respectively. The entire switch elements connected in parallel in this manner will be referred to as a parallel module herein. Parallel module has feed conductor 8
, 9 to the power source 1 and the load 2. The power supply conductors 8 and 9 are wired from connection points 61 and 71 provided on the parallel connection conductors 6 and 7 between the switch elements 41 and 42 to the parallel connection conductors 6 and 7 with a distance W between them.

Next, the switch elements 41 to 43 are connected in this way.
The reason why the shared current can be equalized even if the parallel connection configuration is simplified will be explained.

As shown in FIG. 2, the parallel connection conductor 7 of the cathode terminal
The self-inductance of the power supply conductor 9 facing the parallel-connected conductor 7 is L1, L2, L3.
, L5, and L6, and when the configuration of FIG. 1 is converted into a circuit including the wiring inductance within the module, it can be expressed as shown in FIG. Here, reference is made to an IGBT module in which the module-type switch elements 41 to 43 of FIG. 1 are connected in antiparallel to an IGBT and a diode.

Switch element 4 which is an IGBT module
1 to 43 are IGBTs (411, 421,
431) and diodes (412, 422, 432) are connected in antiparallel, and each connection part (413, 432) of both is connected in antiparallel.
23, 433 and 416, 426, 436) to the surface of the module.
7, 437) and emitter terminals (418, 428, 43
8) There are also wiring inductances L414 and L4 between them, respectively.
25, L434 and L415, L425, L435 exist. In addition, power supply 1 and load 2 are connected to parallel module 8.
Let M1 to M4 be mutual inductances due to the mutual induction effect acting on portions where the power supply conductors 9 and 10 and the parallel connection conductors 6 and 7 are close to each other.

If the characteristics of the switching elements are made equal and the currents shared by each module are made equal, the voltage generated between the collector terminal (for example 417) and the emitter terminal (for example 418) of each module is the same. 9 connection points 61, 71 to the collector terminals 417 of each module,
427, 437 and emitter terminals 418, 428, 4
All that is required is to equalize the voltages generated in the wiring between 38 and 38. Note that since the wiring inductances on the collector terminal side and the emitter terminal side in FIG. 3 are symmetrical, only the emitter terminal side will be explained here to simplify the explanation.

Assuming that the same current i flows through each module, in order to equalize the voltages generated between each module of the parallel connected conductor 71,

[0019]

[Math 1]

Therefore, the condition for equalizing the shared current is

[
0021

[Math 2]

[0022]

[Math 3]

[0023]

[0024] Formulating Equation 2 and Equation 3 may seem very difficult to implement because they utilize mutual induction, but if you take into account the current sharing unbalance rate, it can be implemented relatively easily. I found out that it can be done.

FIG. 4 shows an example of measuring shared current using the parallel connection configuration of FIG. 1. The parameter is the distance W between the power supply conductor 9 and the parallel connection conductor 7. When the interval W is narrowed to 10 mm, the mutual inductance M3 becomes too large due to mutual induction, so the current of IGBT3 (431) is the largest. However, when the distance W is 20 and 40 mm
It can be seen that a good shared current is obtained when .

Furthermore, according to the experimental results, even when the distance W between the power supply conductor 9 and the parallel connection conductor 7 is 70 mm, the IGBT
Although the shared current of 431 decreases slightly, IGBT41
It has been confirmed that the shared currents of 1 and 421 are equalized, and the current unbalance rate does not become so large. The reason why the current unbalance rate does not become so large is that the basic configuration of the parallel connection of the present invention emphasizes equalization of the shared currents of the two switch elements, and is suitable for bringing the shared currents of other switch elements close to this. This is because it is a configuration. Above, the parallel connection method of the present invention has been explained using an example in which three switch elements are connected in parallel, but when there are four or more switch elements,
A switch element will be added between the second and third switch elements. Further, in the embodiment of the present invention, the switch elements are arranged at equal intervals, but in order to make it easier to equalize the sum of the self inductance and mutual inductance from the connection point 71 of the power supply conductor 9 to the cathode terminal of each switch element. In some cases, the spacing between the switching elements may be made uneven. If the spacing is unequal, the wiring will become longer and the self-inductance will increase, which may seem inconvenient for a switch circuit, but as shown in Equations 2 and 3, the configuration is such that the mutual inductance cancels out, so the total inductance is It will only be a slight increase.

Next, a case where the present invention is applied to two switch elements in parallel will be explained.

FIG. 5 shows a sectional view corresponding to the AA section in FIG. 1 when two devices are arranged in parallel. Components that are the same as those in FIGS. 1 to 3 are designated by the same symbols. If the distance between the cathode terminals of the switch elements 41 and 42 is l1, and the distance between the connection point 71 of the power supply conductor 9 and the switch element 42 is l2, then l2 is 1/2.
from the connection point 71 to the switch element 4.
A difference is provided in the self-inductance of the parallel-connected conductors 7 up to the cathode terminals 1 and 42. Then, the power supply conductor 9 is drawn out in parallel to the parallel-connected conductor 7 having the larger self-inductance, so that the sum of the self-inductance and the mutual inductance becomes the same.

Note that when switching elements having different current capacities are connected in parallel, the sum of self inductance and mutual inductance is made to be inversely proportional to the current capacity of the switching elements.

FIG. 7 shows an embodiment in which the parallel connection method of the present invention is applied to the main switch elements of a single-phase inverter device. A single-phase inverter has a DC power supply 1 and a pair of switching elements whose anode terminals and cathode terminals are connected in series by a series connection body 10, and two sets of switching elements are connected in parallel, and a load is applied between each connection point 11 of the series-connected switching elements. 2 is connected. Note that, in order to simplify the drawing, one phase is shown as a block, but the inside of the block has the same configuration as that shown in the drawing. By using the parallel connection configuration of the present invention,
Even though three switch elements are connected in parallel,
It has a very simple configuration.

FIG. 8 shows another embodiment in which the parallel connection method of the present invention is applied to the main switch elements of a single-phase inverter device. The switch element is different from that in FIG. 7, and this is a configuration diagram in the case of using a module in which the anode terminal and cathode terminal of the switch are connected in series.

Although not shown in the figure, if there are a large number of semiconductor switches in parallel, the parallel connection structures configured as shown in FIG. It is effective to connect. Furthermore, if the total number of parallel connections is an odd number, it is preferable to arrange the intermediate semiconductor switches symmetrically around the center.

[0033]

According to the present invention, the shared currents of the parallel switch elements can be equalized, and by actively utilizing mutual induction, the parallel configuration can be simplified and the size can be reduced. Therefore, the utilization rate of the switch element or the reliability is improved, and it is effective to reduce the assembly cost and downsize the switch circuit and the inverter device.

[Brief explanation of the drawing]

FIG. 1 is an assembly diagram when three devices of the present invention are connected in parallel.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is a parallel circuit diagram when wiring inductance is taken into account.

FIG. 4 is a diagram showing an example of shared current waveforms.

FIG. 5 is a diagram showing an example of connection when two devices are connected in parallel.

FIG. 6 is an explanatory diagram of a conventional example.

FIG. 7 is a circuit diagram of an embodiment in an inverter.

FIG. 8 is a diagram showing another embodiment of the inverter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... DC power supply, 2... Load, 3... Diode, 6, 7... Parallel connection conductor, 8, 9... Power supply conductor, 41-43... Module type switch element, 51-53... Control signal wiring, 61, 71 ... Connection point of power supply conductor, 411, 421, 4
31... IGBT, 412, 422, 432... Diode, M1-M4... Mutual inductance, L1-L12... Self-inductance, S1-S4... Switch.

Claims (12)

[Claims] 1. A method for parallel connection of semiconductor switches, wherein the anode terminals and cathode terminals of a plurality of semiconductor switches are respectively connected by parallel connection conductors, and the parallel connection conductors and a power source or load are connected by a power supply conductor. , the connection point of the parallel connection conductor with the power supply conductor is biased toward one end side with respect to the middle point of the parallel connection conductor, and the self inductance of the parallel connection conductor from the connection point to the anode terminal or the cathode terminal at both ends is A method for connecting semiconductor switches in parallel, characterized in that the power supply conductor is arranged so that non-uniformity of the power supply conductor is corrected by mutual inductance between the parallel connection conductor and the power supply conductor. 2. A switch circuit for controlling energy supplied from a power supply to a load using a plurality of semiconductor switches, wherein at least two of the plurality of semiconductor switches are connected in parallel, and the anode terminals of the plurality of semiconductor switches are In a method for parallel connection of semiconductor switches, in which cathode terminals are connected to each other by a parallel connection conductor A, and a power supply conductor B from the power supply and load is connected to the parallel connection conductor A, the anode terminals or cathode terminals of the semiconductor switches are connected to each other by a parallel connection conductor A. A connection point between at least one of the parallel connection conductors A and the power supply conductor B is shifted to one side from a longitudinal midpoint of the parallel connection conductor A,
The self-inductance (L1, L2) of the parallel-connected conductor A from the connection point to the anode terminal or cathode terminal at both ends is made nonuniform (L1<L2), and the self-inductance (L2) of the larger one is reduced. A method for parallel connection of semiconductor switches, characterized in that a mutual induction effect is created between a parallel connection conductor A and the power supply conductor B. 3. A switch circuit for controlling energy supplied from a power supply to a load using a plurality of semiconductor switches, wherein at least three of the plurality of semiconductor switches are connected in parallel, and the anode terminals of the plurality of semiconductor switches are In a semiconductor switch circuit in which cathode terminals are connected by a parallel connection conductor A, and a power supply conductor B from the power source or load is connected to the parallel connection conductor A, at least one of the anode terminals or the cathode terminals is connected in parallel. The connection point between the connection conductor A and the power supply conductor B is biased to one side from the midpoint of the parallel connection conductor A or the central semiconductor switch, and the connection conductor B is drawn out to the other side opposite to the bias. A semiconductor switch circuit featuring: 4. In claim 3, when one end of the parallel semiconductor switch is the first end and the other end is the nth end, the connection portion of the power supply conductor B is the first and second end of the parallel connection conductor A. between the second semiconductor switches, and the power supply conductor B
1. A semiconductor switch circuit characterized in that the semiconductor switch circuit has a configuration in which the second semiconductor switch passes over the n-th semiconductor switch. 5. In claim 4, the distance of the parallel connection conductor A connecting the first and second semiconductor switches is C, and the distance between the first semiconductor switch and the connection point of the power supply conductor B is D. Then, D/C is larger than 1/3,
A semiconductor switch circuit characterized in that it is configured to be smaller than 2/3. 6. The semiconductor according to claim 4, wherein W is 70 mm or less, where W is a distance between the parallel connection conductor A and the power supply conductor B of the n-th semiconductor switch. switch circuit. 7. The switch circuit according to claim 6, wherein the distance W between the parallel wiring conductor A and the connection conductor B is different between the second to nth semiconductor switches. 8. The switch circuit according to claim 3 is arranged symmetrically, and a second power supply conductor B' to the power source or load is connected from an intermediate point thereof. switch circuit. 9. The switch circuit according to claim 8, wherein the number of semiconductor switches connected in an array is an odd number, and the symmetrically arranged semiconductor switches are naturally integrated. 10. The switch circuit according to claim 3, wherein the semiconductor switch is a combination of semiconductor switches having different current capacities. 11. A semiconductor switch circuit according to claim 3, wherein said semiconductor switch is an individual element or module of IGBT or MOS-FET. 12. An inverter device in which at least two or more sets of a pair of semiconductor switches connected in series with a DC power source are connected in parallel, and a load is connected between the series connection points of the pair of semiconductor switches, wherein the semiconductor switch is an IGBT.
or a high-speed switching element such as a MOS-FET, which is a parallel connection of at least two pieces, each of which has its anode terminals connected to itself and its cathode terminals connected to each other by a parallel connection conductor A; 6. An inverter device characterized by using the connection described in any one of 6 above.