JPH07177727A - Gate driving circuit and gate driving method of voltage-driven switching element - Google Patents

Abstract

PURPOSE:To equalize current in voltage-driven switching elements which are connected in parallel by driving the voltage-driven switching elements connected to gate terminals of those switching elements simultaneously through a voltage source. CONSTITUTION:Voltage-driven switching elements, IGBT6A and 6B, are connected in parallel. When the IGBT6A is on, the voltage between a gate and an emitter VGEA is VGA+VEA. When the IGBTs are turned on, current flows between the emitters of the two IGBTs which are connected in parallel and then a voltage drop VL1 is generated by a reactor component 5A which appears in a connecting conductor and the emitter potential VEB of the IGBT6B is VEA+VL1. Since voltage VR1(=LL1) is generated across a reactor 7A correspondingly to the voltage drop due to the reactor component appearing in the connecting conductor between the emitters and thereby the gate potential VGB of the IGBT6B increases to VGA+VR1, the voltage between a gate and an emitter VGEA of the IGBT6A and that VGEB of the IGBT6B can be equal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate driving circuit for a voltage driving type switching element, and more particularly to a plurality of voltage driving type switching circuits connected in parallel which are simultaneously driven by a single gate driving circuit. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device gate drive circuit and a method for driving the same.

[0002]

2. Description of the Related Art Semiconductor switching devices are inverters.
It is widely used for power conversion, power control, and other applications such as switches and choppers, and has become an indispensable element in the power field. Further, in order to cope with the increase in the capacity of electric power, since the capacity of one semiconductor switching element is insufficient, the capacity of the semiconductor switching element is increased by connecting the semiconductor switching elements in parallel. Figure 5
[Fig. 3] is a conceptual diagram when semiconductor switching elements are connected in parallel. In FIG. 5, semiconductor switching element 1A
And 1B are connected in parallel. 2C is a collector-side common terminal, and 2E is an emitter-side common terminal. When performing the switching operation in this circuit, it is necessary to drive the semiconductor switching elements at the same time.

As a semiconductor switching element, a current drive type switching element typified by a thyristor is generally used, but recently, due to the downsizing of the device and the speeding up / off of a switch, an insulating gate bipolar transistor is recently used. The use of voltage-driven switching elements represented by (IGBT) is increasing.

FIG. 6 is a diagram showing two parallel connections of voltage drive type switching elements driven by a single gate drive circuit. In FIG. 6, the voltage driven switching elements 3A and 3B are connected in parallel, and the gate circuit 4 drives the voltage driven switching elements 3A and 3B at the same time. 2C is a collector-side common terminal, and 2E is an emitter-side common terminal. In the voltage-driven switching element like this circuit, a plurality of voltage-driven switching elements can be simultaneously driven by using a single gate circuit.

[0005]

In the structure as shown in FIG. 6, the connecting conductor between the emitters of the voltage driven switching elements 3A and 3B has a certain reactor component. FIG. 7 is a schematic diagram showing two parallel connections of voltage drive type switching elements driven by a single gate drive circuit in which the inductance value of the reactor component is L1. In FIG. 7, 5A is a reactor component generated in the connection conductor, and the inductance value is L1. The other elements have the same configuration as in FIG.

When a current is flowing through the voltage-driven switching element, a voltage drop V _L1 proportional to the time derivative of the current shown below is generated between the emitters due to the reactor component.

[0007]

[Equation 1] However, in the above formula, i is a current flowing through the connection conductor. Further, since the current flowing through the gate is sufficiently smaller than the current flowing through the inter-emitter connecting conductor, the occurrence of voltage drop in the gate wiring can be almost ignored.

The gate potential V _GA of the voltage drive type switching element 3A and the gate potential V _GB of the voltage drive type switching element 3B are equal potential V _GA = V _GB , but the emitter of the voltage drive type switching element 3B The potential V _EB is V _EB = V _EA +
It becomes V _L1 . Therefore, the voltage-driven switching element 3A
The gate-emitter voltage V _GEA is expressed by the following equation.

[0009]

On the other hand, V _GEA = V _GA −V _EA
The emitter-to-emitter voltage V _GEB is given by the following formula.

[0010]

[ _Expression 3] V _GEB = V _GB −V _EB = V _GB −V _EA −V _L1 Therefore, the voltage drive type switching elements 3A and 3B are gated.
The voltage between the emitter and the emitter is not equal, and as a result, there is a problem in that current does not flow evenly through the voltage-driven switching elements 3A and 3B during a transition. Therefore, the present invention is a simple game.
It is an object of the present invention to equalize the currents of the voltage-driven switching elements connected in parallel with each other in a drive circuit configuration.

[0011]

In order to achieve the above object, a gate drive circuit for a voltage drive type switching element according to claim 1 of the present invention uses a connection conductor for connecting each collector terminal and each emitter terminal. In a gate drive circuit for a voltage-driven switching element that drives the gates of a plurality of voltage-driven switching elements connected in parallel, this occurs in the emitter-to-emitter connection conductor of each voltage-driven switching element connected in parallel. A voltage source for generating a voltage corresponding to the voltage drop of the reactor component, and a driving means for simultaneously driving the voltage driving type switching element connected to the gate terminal of the voltage driving type switching element via the voltage source. There is provided a gate drive circuit of a voltage drive type switching element characterized by having.

According to a second aspect of the present invention, there is provided a method of driving a gate of a voltage-driven switching element, wherein a plurality of voltage-driven switching elements in which collector terminals and emitter terminals are connected in parallel by connecting conductors. In the gate driving method of the voltage-driven switching element that drives the gate, the voltage corresponding to the voltage drop of the reactor component generated in the inter-emitter connection conductor of each voltage-driven switching element connected in parallel is generated. Thus, there is provided a gate driving method of a voltage driving type switching element, in which the voltage is applied to the gate terminal of the voltage driving type switching element to drive the voltage driving type switching element simultaneously.

[0013]

As described above, in the present invention, the emitter potential of each switching element is affected by the voltage drop due to the reactor component generated in the inter-emitter connecting conductor of each switching element connected in parallel. Therefore, a voltage corresponding to the voltage drop due to the reactor component is applied to the gate power supply to raise the gate power supply, thereby equalizing the currents among the plurality of voltage-driven switching elements connected in parallel.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of the present invention. In this embodiment, an insulated gate bipolar mode transistor (hereinafter referred to as IG) is used as a voltage driving type switching element.
BT). In FIG. 1, the IGBT
6A and the IGBT 6B are connected in parallel, and a reactor component 5A is generated in the connecting conductor between the emitters. Gee
The circuit 7 is a circuit for driving the above-mentioned IGBT.
6A is directly connected, and a reactor 7A in which a gate wire is wound around the connection conductor between the emitters is connected to the IGBT 6B so as to generate a voltage equal to the voltage drop V _L1 due to the reactor component 5A generated in the connection conductor between the emitters. Connect through. In FIG. 1, the gate-emitter voltage V _GEA when the IGBT 6A is ON is given by the following equation.

[0015]

[ _Equation 4] V _GEA = V _GA −V _{EA When the} IGBT is turned on and a current flows, the two are connected in parallel.
A current flows between the emitters of the two IGBTs, causing a voltage drop V _L1 due to the reactor component 5A generated in the connecting conductor. At this time, the emitter potential of the IGBT 6B is given by the following formula.

[0016]

[Equation 5] V _EB = V _EA + V _{L1 Further} , the reactor 7A in which the gate wire is wound around the inter-emitter connection conductor has a voltage V _R1 (= which depends on the voltage drop due to the reactor component generated in the inter-emitter connection conductor. V _L1 ) is generated and the gate potential of the IGBT 6B is raised, so the gate potential V _GB is expressed by the following formula.

[0017]

[Equation 6] V _GB = V _GA + V _{R1 The} gate-emitter voltage of the IGBT 6B is given by the following equation according to [Equation 5] and [Equation 6].

[0018]

## _EQU7 ## V _GEB = V _GB + V _EB = (V _GA + V _R1 ) − (V _EA + V _L1 ) = V _GA −V _EA = V _GEA Therefore, the gate-emitter voltage V _{GEA of the} IGBT 6A and the IGBT 6B is obtained. V _GEB can be equal.

FIG. 2 illustrates the operation of the first embodiment. IGBT6A and IGBT6B connected in parallel
The voltage drop caused by the reactor component 5A generated in the emitter-to-emitter connection conductor is V _L1 . A voltage V _R1 corresponding to the above voltage drop is generated by the voltage source 8A.
The voltage source 8A corresponds to the reactor 7A in which the gate wire is wound around the inter-emitter connection conductor in FIG.

IGBT 6A and IGBT connected in parallel
In order to drive 6B and 6B at the same time, it may be driven by a single gate circuit, but the voltage drop V _L1 due to the reactor component generated in the emitter-to-emitter connecting conductor between IGBT 6A and IGBT 6B is not stable. . So IGB
If the gate circuit is not directly connected to T6B but is connected via the voltage source 8, the voltage of the voltage source 8 increases and a voltage is applied to the gate of the IGBT 6B.
A uniform current flows through the GBT.

According to this embodiment, even if a single gate circuit is used, it is possible to correct the variation in the gate voltage caused by the emitter-to-emitter connecting conductors connected in parallel, and the parallel connection I
This has the effect of equalizing the currents flowing through the GBT 6A and the IGBT 6B.

Next, a second embodiment of the present invention will be described. FIG. 3 is a schematic diagram showing a second embodiment of the present invention in which three IGBTs are connected in parallel. In FIG. 3, the IGBT 6A
The IGBT 6B and the IGBT 6C are connected in parallel. The reactor component 5A is generated in the inter-emitter connection conductor between the IGBT 6A and the IGBT 6B, and the IGBT 6B and the IG
Reactor component 5 is used for the emitter-to-emitter connection conductor with BT6C.
B occurs. The gate circuit 4 is a circuit for driving the above-mentioned IGBT and is directly connected to the IGBT 6A.
Is connected through a reactor 7A having a gate wire wound around the emitter connecting conductor so as to generate a voltage equal to a voltage drop V _L1 due to a reactor component 5A generated in the emitter connecting conductor between the IGBT 6A and the IGBT 6B. ,
A gate line is connected to the emitter connecting conductor so as to generate a voltage equal to the voltage drop V _L2 due to the reactor component 5B generated in the emitter connecting conductor between the IGBT 6B and the IGBT 6C by branching the IGBT 6C connected to the IGBT 6B. Is connected via a reactor 7B wound around.

In this circuit, the same results as those of the first embodiment are obtained with respect to the base-emitter voltage of the IGBT 6A and the base-emitter voltage of the IGBT 6B. Therefore, considering the gate-emitter voltage of the IGBT 6C, when the IGBT is turned on and a current flows, a current flows between the emitters of the three IGBTs connected in parallel,
Voltage drops V _L1 and V _L2 are generated by the reactor components 5A and 5B generated in the connecting conductor. At this time, the IGBT6C
The emitter potential of is as follows.

[0024]

[Equation 8] V _EC = V _EA + V _L1 + V _{L2 Further} , the reactors 7A and 7B in which the gate wire is wound around the emitter-to-emitter connection conductor have a voltage corresponding to the voltage drop due to the reactor component generated in the emitter-to-emitter connection conductor. V _R1 (= V
_{Since L1} ) and V _R2 (= V _L2 ) are generated to raise the gate potential of the IGBT 6C, the gate potential V _GC is given by the following formula.

[0024]

## EQU9 ## V _GC = V _GA + V _R1 + V _{R2 Further} , the gate-emitter voltage of the IGBT 6C is given by the following formula.

[0025]

[ _Equation 10] V _GEC = V _GC −V _EC = (V _GA + V _R1 + V _R2 ) − (V _EA + V _L1 + V _L2 ) = V _GA −V _EA Therefore, from [Equation 7] and [Equation 10], the IGBT 6A is obtained. IG
Gate-emitter voltage V between BT6B and IGBT6C
_GEA , V _GEB and V _GEC are all equal. Therefore, in this embodiment, even if the three IGBTs are connected in parallel, it is possible to correct the variation in the gate voltage caused by the inter-emitter connection conductor and make the gate-emitter voltage of each IGBT equal.

Similarly, even if four or more IGBTs are connected in parallel, the gate-emitter voltage of each IGBT can be made equal. Next, a third embodiment of the present invention will be described. FIG. 4 shows a third embodiment in which a transformer is inserted in the emitter connecting conductor as a voltage source which is a means for correcting the gate voltage. In FIG. 4, IGBT 6A and I
It is connected in parallel with the GBT 6B, and a reactor component 5A is generated in the connecting conductor between the emitters. Gate circuit 4
Is a circuit for driving the IGBT, which is directly connected to the IGBT 6A and is connected to the IGBT 6B through the transformer 9. The transformer 9 is inserted so that the inter-emitter connection conductor passes through the core, and the IGBT 6 is provided on the secondary side of the transformer 9.
It is assumed that the coil is wound so that a voltage equal to the voltage drop of the inter-emitter connection conductor of the A and IGBT 6B is generated. Therefore, the transformer 9 generates a voltage V _R1 corresponding to the voltage drop V _L1 across the emitter-to-emitter connection conductor on the secondary side of the transformer 9 and raises the gate potential of the IGBT 6B by V _R1 . As a result, the IGBT6A and the IGBT6B are connected to each other.
The voltage between the emitter and emitter can be made equal.

The same effect can be obtained by installing a reactor load on the secondary side of the current transformer instead of the transformer 9 and inducing V _R1 . In the above description, the IGBT is used as the switching element, but other switching elements,
For example, MOS thyristor (Mos Controled Thyristor)
: MCT) can be used to obtain the same effect.

[0028]

As described above, according to the present invention, since the gate-emitter voltage of a plurality of voltage-driven switching elements connected in parallel can be controlled equally, the gate caused by the connecting conductors for parallel connection can be controlled. -It is possible to eliminate variations in voltage and to equalize currents among a plurality of voltage-driven switching elements connected in parallel.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a third embodiment of the present invention.

FIG. 5 is a conceptual diagram of conventional parallel connection of switching elements.

FIG. 6 is a schematic diagram of parallel connection of conventional voltage-driven switching elements.

FIG. 7 is a schematic diagram including a problem of parallel connection of conventional voltage-driven switching elements.

[Explanation of symbols]

4 ... Gate connection circuit 5A, 5B ... Reactor component generated in inter-emitter connection conductor 6A, 6B, 6C ... Voltage-driven switching element 7A, 7B ... Reactor wound around emitter-connection conductor 8A, 8B ... Voltage source 9 … Transformer

Claims (2)

[Claims] 1. A gate drive circuit of a voltage drive type switching element for driving a gate of a plurality of voltage drive type switching elements in which respective collector terminals and respective emitter terminals are connected in parallel by connecting conductors, A voltage source that generates a voltage corresponding to the voltage drop of the reactor component generated in the emitter-to-emitter connection conductor of each connected voltage-driven switching element, and the gate of the voltage-driven switching element via the voltage source. And a driving means for simultaneously driving the voltage-driven switching element connected to the terminal.
Drive circuit. 2. A gate driving method of a voltage driving type switching element for driving a gate of a plurality of voltage driving type switching elements in which each collector terminal and each emitter terminal are connected in parallel by a connecting conductor, A voltage corresponding to the voltage drop of the reactor component generated in the emitter-to-emitter connection conductor of each connected voltage-driven switching element is generated, and the voltage is generated by the gate of the voltage-driven switching element.
A gate driving method for a voltage-driven switching element, characterized in that the voltage-driven switching element is driven simultaneously with the gate terminal.