JPH0583954A - Parallel connecting method of semiconductor switch and capacitor and switch circuit and inverter - Google Patents

Abstract

PURPOSE:To improve application rate of switch element and realize reduction of size by dividing a filter capacitor, equalizing inductance of wiring viewed from each of switch elements connected in parallel, lowering inductance of a power supply wiring viewed from each of filter capacitor and t-he equalizing the bearing currents. CONSTITUTION:Filter capacitors 11, 12, 13 are respectively divided, wirings L71, L73, L75 are laid symmetrically to switch elements S1, S3 and S5. Thereby, fluctuation of wiring inductances L71, L73, L75 is lowered to equalize bearing currents immediately after turning ON. Moreover, the filter capacitors 11, 12, 13 are connected in parallel with conductors and are arranged in parallel with a power feeding line from the power supply. Accordingly, a total inductance can be balanced with the mutual inductance between such elements. Steady currents flowing into the switch elements S1, S2, S3 are equalized by equalizing the current flowing into the filter capacitors 11, 12, 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallel connection method for semiconductor switch elements, and more particularly to a parallel connection method suitable for equalizing the shared currents of a parallel semiconductor switch element and a filter capacitor connected in parallel to supply a current thereto. In addition, the present invention relates to a switch circuit and an inverter device suitable for simplifying the configuration and downsizing the shape.

[0002]

2. Description of the Related Art Semiconductor switching devices (IGBT, GT
Since the current capacity of a single O, bipolar transistor, etc.) is limited, semiconductor switch elements (hereinafter abbreviated as switch elements) are connected in parallel when a larger current capacity is required. When connecting the switch elements in parallel, what is important is to make the sharing currents of the parallel switch elements equal.

The shared current of each parallel switch element is determined by the difference between the characteristics of the switch element and the parallel wiring. Recently, the manufacturing technology of switch elements has improved, and it has become relatively easy to select switch elements having uniform characteristics. Therefore, if the difference in parallel wiring is made small, direct parallel connection without using a current balancer, which has been often used, has become possible (JP-A-60-
102883, JP-A-62-160069). In direct parallel connection, it is important to configure so as to reduce the difference in inductance between parallel wirings.
Proposals such as Japanese Patent No. 5 have been made.

The point of the above technique is to avoid mutual induction between wirings and to arrange the self-inductances of parallel wirings. This method is a suitable method when two switch elements are connected in parallel.

[0005]

However, in the method of the prior art, if the number of switching elements in parallel increases, parallel wiring becomes considerably difficult. For example, when four units are connected in parallel, the structure shown in FIG. 6 is considered. Two parallel connections will be further connected in parallel, and if the wirings are separated to avoid mutual induction between the wirings, there arises a problem that the parallel connection configuration becomes complicated and has a large shape.

Another method is to increase the allowable value of the shared current imbalance ratio and simplify the parallel connection configuration of the switch elements for use. However, in order to secure reliability, it is necessary to increase the number of switching elements in parallel, which eventually causes a problem that the shape becomes large.

Therefore, an object of the present invention is to make the shared currents of the respective parallel switch elements equal, to simplify the structure, and to make the shape compact, and to make the parallel connection method suitable, and to make the structure simple and make the shape compact. It is to provide a switch circuit and an inverter device.

[0008]

In order to achieve the above object, a switch element and a filter capacitor for supplying a current to the switch element are paired and connected in parallel so that the shared current of each parallel switch element and the filter capacitor is reduced. We have found parallel wiring configurations that are almost even. For example, n
When the switch elements are connected in parallel, the filter capacitor is divided into n pieces, and the filter capacitor and the switch elements are connected by equal wirings. That is, the first means is to equalize the wiring inductance from the parallel switch elements to the filter capacitor.

Next, the variation in the inductance of the power supply wiring viewed from each parallel filter capacitor is reduced as follows. A connection point between the power feeding conductor C from the power source and the parallel connection conductor D of the filter capacitor is provided between the first and second filter capacitors. Then, the distance W between the power feeding conductor C from the power source and the parallel connection conductor D is brought close to 70 mm or less and is drawn out to the n-th filter capacitor side, and a mutual induction action is exerted between both wirings. The second means is to reduce the variation in the inductance of the power supply wiring viewed from each parallel filter capacitor by utilizing the mutual induction action between the wirings.

A switch circuit and an inverter device are constructed by using such a parallel connection method.

[0011]

When the filter capacitors are divided and connected to the respective parallel switches as in the above configuration, it is easy to equalize the wiring from each filter capacitor to each switch element, and the wiring inductance seen from the parallel switch element is equalized. it can. As a result, the equalized wiring inductance acts as a current balancer, and the transient shared currents of turn-on and turn-off of the switch elements are equalized more than those determined by variations in element characteristics.

[0012] The variation of the inductance of the power supply wiring seen from each parallel filter capacitor also affects the shared current during the steady ON state. The current flowing from the power supply to the filter capacitor is an average of the load current. Since the current change rate (di / dt) is small, the influence of the wiring inductance variation (ΔL) (ΔL · di / dt) is relatively small. .. However, when the load current with a sharp current change or the capacitance of the filter capacitor is reduced, the variation in the inductance of the power supply wiring cannot be ignored. According to the above power supply wiring configuration, the self-inductance of the parallel connection conductor D based on the connection point of the power supply conductor C from the power supply to the filter capacitor is the largest at the n-th filter capacitor and the first and second filter capacitors. Are almost the same. The currents of the third to nth filter capacitors also flow in the parallel connection conductor D between the connection point of the power feeding conductor C and the second filter capacitor. Therefore, the voltage generated in the self-inductance of the parallel connection conductor D when a current flows through each filter capacitor is the largest at the n-th filter capacitor with respect to the connection point of the feeding conductor C, and the first filter capacitor. The dancer is the smallest.

On the other hand, a mutual induction action is exerted between the parallel connection conductor D and the feeding conductor C between the second to nth filter capacitors, and the mutual inductance is between the second to nth filter capacitors. Parallel connection conductor D
Acts to equivalently reduce the self-inductance of.
The magnitude of the mutual inductance can be changed by the distance W between the feeding conductor C and the parallel connection conductor D. That is, the mutual inductance acting on the second to nth parallel-connected conductors D can be varied to reduce the variation in the inductance of the power supply wiring viewed from each parallel filter capacitor.

[0014]

The present invention will be described below in detail with reference to the drawings of the embodiments.

FIG. 1 is a configuration diagram of parallel connection showing an embodiment of the present invention. Three modules each containing two switching elements connected in series form a stack for one phase of the inverter. The wiring between the power supply and the filter capacitor is omitted to avoid complication of the drawing.

In FIG. 1, 11 to 13 are filter capacitors, 21 to 23 are modules containing two switching elements, and 31 to 33 are ones connected in series (P side arm).
Anode terminals 41 to 43 of the other element (N-side arm) are cathode terminals of the other element (N-side arm) 51 to 53 are series connection points of the switching elements, which are connected in parallel by the wiring conductor 6. The wiring conductor 6 is connected to a load (not shown). The positive electrode (P) terminal and the negative electrode (N) terminal of the filter capacitor are connected in parallel by a conductor D, and wiring conductors 71 to 76 are connected to the anode terminal (31 to 33) and the cathode terminal (41 to 43) of the module. It is connected. And in fact,
The drive circuits 81 and 82 for controlling on / off of the switch elements of the modules 21 to 23 are connected to the modules via signal wirings, but are not shown here to avoid complication.

Next, the reason why the shared currents can be equalized by using such a parallel connection configuration will be described with reference to a circuit diagram.

From the assembly structure shown in FIG. 1, the wiring inductance, which affects the current shared by the switch elements, can be used as a main circuit to form a circuit as shown in FIG. Figure 1 here
Modules 21 to 23 of two IGs connected in series
BTs and IGBTs in which diodes are connected in antiparallel
Is quoted from the module.

The IGBTs in modules 21 to 23 are
1 to S6, and the diodes are D1 to D6. And the connection point of both anti-parallel connection and the terminal 3 drawn out on the surface of the module
The wiring inductance between 1 to 33 and 41 to 43 is L
Let _{211 to} L ₂₁₄ , L _{221 to} L ₂₂₄ , and L _{231 to} L ₂₃₄ .
The inductances of the wiring conductors _{71 to 76} between the filter capacitor and the terminals 31 to 33 and 41 to 43 of the module are L _{71 to} L ₇₆ . Further, the inductances of the signal wirings from the drive circuits 81 and 82 for controlling the ON / OFF of the IGBT are L _{G11 to} L _G14 , L _{G21 to} L _G24 and L _{G31 to} L _G34 . Since the on / off timing of the switch elements is affected by the variation in the inductance of the signal wiring, the signal wirings of the switch elements S1 to S6 are arranged in the same wiring length so that the inductances are uniform.

In the circuit configuration as described above, the shared current when the switch elements S2, S4, S6 are in the off state and S1, S3, S5 are turned on and off will be described.

When an ON signal is given from the drive circuit 81, the switch elements S1, S3, S5 shift from the OFF state to the ON state according to their characteristics if the inductances of the signal wirings are equal. The current paths at this time are from the filter capacitors 11, 12, 13 to the wirings 71, 7 respectively.
3,75 and S1, S3, S5 to the load. In addition, from the other terminal of the load, a switch (power source (N))-filter capacitor 11, 1 of another phase (not shown) is provided.
There are 2 and 13 routes.

If the switch elements S1, S3, S5 have the same characteristics, these switches are turned on at the same time, so that the shared current immediately after turn-on causes the wiring inductance in the module and the filter capacitors 11, 12,
It is determined by the variation of the wiring inductances L ₇₁ , L ₇₃ , and L ₇₅ from 13. Since the variation of the wiring inductances L _{211 to} L _{232 in} the module between the modules is small, the inductances L ₇₁ , L ₇₃ , and L ₇₅ of the wiring conductors _{71 to 76} from the filter capacitors 11, 12, and 13 are shared immediately after turn-on. It will determine the current.

In the configuration of the present invention, the filter capacitor 1
1, 12 and 13 are divided and switch elements S1, S3 and
The wirings 71, 73, 75 to S5 are made symmetrical. Therefore, variations in the wiring inductances L ₇₁ , L ₇₃ , and L ₇₅ are small, and equalization of the shared current immediately after turn-on is realized. Even if it is simply considered, since the external circuit seen from the switch element is made uniform, it can be easily estimated that the shared currents at turn-on and turn-off are even if the characteristics of the switch element are the same.

The above is an example of the case where the characteristics of the switch elements are uniform. Next, the switch elements S1 and S will be described.
Among S3 and S5, the operation in the case where S1 has a faster turn-on and a slower turn-off than S3 and S5 will be described.

When an ON signal is applied to the switch elements S1, S3, S5 from the drive circuit 81, S1 first starts to be in an ON state, and the filter capacitor 11 causes L ₇₁ , S1.
Current begins to flow through the load to the load. When a current starts flowing, a voltage is induced in L ₂₁₂ (L ₂₃₂ × di ₁ / dt) in proportion to the current change rate di ₁ / dt. This induced voltage is L
It is applied to L _G22 , L ₂₂₂ and L _G32 , L ₂₃₂ via _G12 , respectively. At this time, the direction of the applied voltage viewed from the drive circuit 81 is opposite between L _G12 and L _G22 , L _G32 . That is, when viewed from between the gate and emitter of S1, the applied voltage of L _G12 acts to reduce the ON signal of the drive circuit 81, and when viewed from between the gate and emitter of S3 and S5, L
The applied voltage of _G22 and L _G32 works so as to increase the ON signal of the drive circuit 81.

Specifically, when S1 having a fast turn-on begins to turn on, the ON signal current flowing in S1 decreases and is distributed to S3 and S5. Therefore, S
The difference in turn-on time between 1 and S3, S5 has become smaller,
Immediately after the turn-on of the three parties, the shared current is equalized.

The effect of the induced voltage of the wiring inductance in the module changing the distribution of the signal currents of the switch elements connected in parallel to make the switching speed uniform is the same in the case of turn-off. In the above example, when the OFF signal (negative polarity) is sent from the drive circuit 81, S3 and S5 start to be in the OFF state first, and the current to the load flowing there is reduced. An induced voltage is generated in L ₂₂₂ and L ₂₃₂ according to the current change rate, and this is generated via L _G22 and L _G32 to L _G12 and L _212.
Applied to. That is, it becomes the same as that at the turn-on described above. When it is off, the voltage applied to L _G12 works to increase the off signal of the drive circuit 81 when viewed from the gate and emitter of S1, and when viewed from the gate and emitter of S3 and S5, L _G22 and L The applied voltage of _G32 acts to reduce the off signal of the drive circuit 81. That is, when S3 and S5, which have fast turn-off, start to turn off,
The off signal current flowing there is reduced and distributed to S1. Therefore, the difference between the turn-off times of S1 and S3, S5 becomes small, and the shared currents at the turn-off of the three parties are equalized.

As described above, the present invention realizes equalization of shared currents at turn-on and turn-off of the switch element by equalizing the wiring inductance seen from the switch element with a simple configuration. .. If the inductance of the wiring seen from the switch element is not uniform, even if the characteristics of the switch elements are the same,
The shared current at turn-off is not uniform. That is, L ₇₁ , L
_This is because the variations in ₇₃ and L ₇₅ determine the shared current.

Further, since the divided individual filter capacitors have a small shape, they can be arranged beside the switch element or close to the upper part thereof. As a result, the inductance of the main circuit wiring is reduced, so that the main circuit loss is reduced and the stack shape can be reduced.

The embodiments for equalizing the inductance of the wiring from the switch element to the filter capacitor have been described above. This makes it possible to equalize the shared currents immediately after turn-on, but if the currents flowing into the filter capacitors are not uniform, the ON steady current (average current) flowing through the switch elements will naturally vary over time. Next, the parallel connection method of filter capacitors is shown.

FIG. 3 shows an embodiment of a parallel connection method of filter capacitors. Filter capacitors 11, 12, 1
3 is connected in parallel with the conductor D, the feeding conductor C from the power source is parallel to the parallel connection conductor D with a distance W, and is connected to the parallel connection conductor D at approximately the middle of the filter capacitors 11 and 12.

According to the above configuration, the self-inductance seen from the power source side is maximum up to the filter capacitor of 13. However, since the power feeding conductor C from the power source and the parallel connection conductor D are arranged in parallel with the interval W, mutual inductance is generated between them and the total inductance can be balanced.

Assuming that an equal current i flows through each filter capacitor 11, 12, 13, in order to equalize the voltage generated between the filter capacitor connections of the parallel connection conductor D, L ₂ and L ₄ and L ₃ and L ₅ If the mutual inductances between them are M ₁ and M ₂ , respectively (di / dt) L ₁ = 2L ₂ (di / dt) -3M ₁ (di / dt) (Equation 1) and (di / dt) L ₁ = 2L ₂ (di / dt) -3M ₁ (di / dt) + L ₃ (di / dt) -3M ₂ (di / dt) (Equation 2), the condition for equalizing the shared current is L ₁ = 2L ₂ -3M ₁ ... (number 3) L ₃ = a 3M ₂ ... (Equation 4).

Although it is very difficult to completely realize the equations 3 and 4, the characteristics of the switching elements cannot be perfectly aligned in reality, so if the unbalance rate of the shared current is expected to be about 5 to 15%. , I found that it can be implemented relatively easily.

FIG. 4 shows an example of measuring the shared current in the parallel connection configuration of the present invention. The shared currents for turn-on and turn-off are well aligned, and good steady-state currents are obtained for almost steady ON, which is determined by the device characteristics (difference in ON voltage).

Incidentally, FIG. 5 shows an example in which the current flowing from the power supply to the filter capacitor is non-uniform. Figure 1
With this configuration, the turn-on is good, but the difference in the on-steady shared current increases with time.

In order to avoid such a phenomenon, the configuration of FIG. 3 is used as the measurement result of FIG. In the case of FIG. 4,
The distance W between the power supply conductor C from the power source and the parallel connection conductor D is 30.
Although it is in the case of mm, it has been confirmed that even when the distance W is 70 mm, the unbalance rate of the shared currents of the parallel switching elements does not become so large. This is because the basic configuration of the parallel connection of the filter capacitors of the present invention places importance on equalization of the shared currents of the two filter capacitors and makes the shared currents of the other filter capacitors close to this. That is, even if a small shared current is generated, a large one is unlikely to be generated.

The parallel connection method of the filter capacitors described above is also effective as a parallel connection method of semiconductor switches. It has been confirmed that a good shared current can be obtained even if the filter capacitor in FIG. 3 is changed to a semiconductor switch.

The parallel connection method of the present invention has been described above with reference to an example in which three switch elements and filter capacitors are connected in parallel. However, when the number of switch elements is four or more,
A filter capacitor may be added in pairs with it. Also, the total number of filter capacitors need not be the same as the total number of switch elements. The purpose of dividing the filter capacitor is to make the wiring between the switch element and the filter capacitor symmetrical, and it is possible to add a filter capacitor to reduce the voltage ripple.

FIG. 7 shows an embodiment of the single-phase inverter of the present invention. A single-phase inverter can be constructed only by connecting two stacks of the present invention in parallel and connecting a load between the output terminals 6 of each stack. Naturally, if there are 3 book stacks, 3
A phase inverter can be realized with a simple structure, and by connecting the stacks in parallel, a switch circuit or an inverter with a larger current capacity can be realized. That is, since the size of the stack is standardized and the number of parallel stacks can be selected according to the capacities of the switch circuit and the inverter, design and assembly cost advantages are also great.

In the above, the embodiment has been described by using the inverter.
The present invention relates to a parallel connection method for semiconductor switches, and its use is not limited to inverters. For example, if the switches S2, S4, S6 of FIG. 2 are removed and the other terminal of the load is connected to the N side terminal of the filter capacitor, a chopper circuit is formed. The parallel operation of the semiconductor switches in this case is similar to that described above, and it is clear that it is also effective for the chopper circuit.

[0042]

As described above, the present invention realizes equalization of the wiring inductance seen from the switching elements connected in parallel, and makes the sum of the self-inductance and the mutual inductance of the parallel connection wiring of the filter capacitors equal to each other. The equalization of the shared current of the switch elements is realized. Therefore, the utilization factor of the switching element is improved, so that the configuration of the device is simplified, downsized, or the reliability is improved.
It is effective in reducing the assembly cost and miniaturizing the switch circuit and the inverter device.

[Brief description of drawings]

FIG. 1 is a parallel assembly diagram of the first invention.

FIG. 2 shows a parallel circuit in consideration of wiring inductance.

FIG. 3 is a parallel assembly diagram of the second invention.

FIG. 4 shows an example of a shared current waveform.

FIG. 5 shows a conventional shared current waveform example.

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

FIG. 7 shows an embodiment using an inverter.

[Explanation of symbols]

11-13 ... Filter capacitors, 21-23 ... Modules, 31-33 ... Anode terminals, 41-43 ... Cathode terminals,
51-53 ... Series connection points of switch elements, 6 ... Parallel connection conductors, 71-73 ... Main circuit wiring, 81, 82 ... Drive circuit, S1-S6 ... IGBT, D1-D6 ... Diode,
M _1, M ₂ ... mutual inductance, L ₁ ~L ₆ ... self-inductance, C ... feed conductor, D ... parallel connection conductors.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Kano 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory

Claims (16)

[Claims] 1. A semiconductor switch circuit in which anode terminals or cathode terminals of a plurality of semiconductor switches are respectively connected by parallel connection conductors, and the parallel connection conductors and a power supply or a load are connected by a power supply conductor, wherein the power supply is provided. A semiconductor switch circuit, wherein at least two or more filter capacitors are connected in parallel with each other, and the anode terminal or the cathode terminal of the semiconductor switch and the filter capacitor are connected by a plurality of feeding conductors. 2. A semiconductor switch circuit in which anode terminals or cathode terminals of a plurality of semiconductor switches are respectively connected by parallel connection conductors, and the parallel connection conductor and a power supply or a load are connected by a power supply conductor, wherein the power supply is provided. In the above, the same number or more filter capacitors as the number of parallel semiconductor switches are connected in parallel, and each anode terminal or each cathode terminal of the semiconductor switch and each filter capacitor are connected by a power supply conductor. A semiconductor switch circuit. 3. The semiconductor switch according to claim 2, wherein at least one of the parallel connection conductors of the anode terminal and the cathode terminal of the semiconductor switch is also used as a power supply conductor between the semiconductor switch and the filter capacitor. The semiconductor switch circuit. 4. The module according to any one of claims 1 to 3, wherein the two semiconductor switches are connected in series, and the series connection point is connected to a load.
Semiconductor switch circuit. 5. The wiring according to claim 4, wherein one of the anode terminals and the other of the cathode terminals of the semiconductor switch and each of the positive and negative terminals of the filter capacitor are connected together. A semiconductor switch circuit. 6. The semiconductor device according to claim 1, wherein an anode or cathode terminal surface of the semiconductor switch and a terminal surface of the filter capacitor are arranged in parallel to each other.
Semiconductor switch circuit. 7. The semiconductor switch circuit according to claim 1, wherein the anode and cathode terminal surfaces of the semiconductor switch and the terminal surface of the filter capacitor are arranged substantially at right angles. 8. A semiconductor switch circuit in which anode terminals or cathode terminals of a plurality of semiconductor switches are respectively connected by parallel connection conductors, and the parallel connection conductors are connected to a power supply or a load by a power supply conductor C, At least two filter capacitors are connected to the power supply by parallel connection conductors D, and the semiconductor switch and the filter capacitor are connected by a plurality of power supply conductors, and the parallel connection conductor D and the power supply conductor C from the power supply are connected. The parallel connection method of filter capacitors, characterized in that the portion is biased to one side from an intermediate point in the longitudinal direction of the parallel connection conductor D, and the feeding conductor C is drawn out on the side opposite to the biased side. 9. The connecting portion of the feed conductor C according to claim 8, wherein one end of the parallel filter capacitor is the first end and the other end is the nth end. A parallel connection method of filter capacitors, characterized in that the feed conductor C is between the nth filter capacitors and passes over the nth filter capacitor. 10. The parallel wiring conductor D and the feeding conductor C of an n-th filter capacitor according to claim 8 or 9.
A method of connecting filter capacitors in parallel, wherein W is 70 mm or less, where W is a distance between them. 11. The parallel connection method of filter capacitors according to claim 10, wherein a distance W between the parallel wiring conductor D and the feeding conductor C is different between the second to nth filter capacitors. 12. A semiconductor switch circuit according to claim 1, wherein the semiconductor switch is an individual element or module of an IGBT or a MOS-FET. 13. An inverter device in which at least two pairs of semiconductor switches connected in series are connected in parallel to a DC power source, and a load is connected between the series connection points of the pair of semiconductor switches, wherein the semiconductor switches are A high-speed switching element such as an IGBT or a MOS-FET, which is a parallel connection body of at least two or more, and either one of the anode terminals or each of the cathode terminals is connected by a parallel connection conductor 6. An inverter device using the connection method according to any one of claims 1 to 11. 14. A semiconductor switch having at least two pairs of semiconductor switches connected in series, the series connection points of which are connected in parallel, and one anode terminal and the other cathode terminal of the series connected semiconductor switches are connected in parallel. One-phase stack of inverter devices, characterized in that they are connected to separate filtered capacitors. 15. An inverter device comprising two or more stacks according to claim 14 connected in parallel. 16. An inverter having a configuration in which a series connection circuit of at least two or more semiconductor switches is a unit switching circuit, and a plurality of the unit switching circuits are connected in parallel to supply electric power to a load from a connection point of the semiconductor switches. In the device, an anode device and a cathode end of the unit switching circuit are connected to a filter capacitor by a power supply conductor, and the filter capacitors are connected in parallel to a power source, and the inverter device is configured.