JP2000316232A - Protective device for power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the constitution of a protective device for power converter with respect to the secondary failure of the accident caused by the break of open module semiconductor elements which occurs when a power supply short- circuiting fault, etc., occurs, by connecting a serial body of a semiconductor element which is energized with a prescribed voltage or higher and a fuse in parallel with both ends of the module semiconductor elements. SOLUTION: A serial body of a semiconductor element 66 which is energized through breakover or breakdown at a prescribed voltage or higher and a fuse 67 is connected in parallel with both ends of module semiconductor elements (IGBTs) 61 and 62 constituting the upper and lower arms of the converters 6, 7, and 8 in three phases of the power converter of a two-level three-phase inverter. When a power supply short-circuiting fault where both the IGBTs 61 and 62 are conducted by noise malfunctions, etc., occurs, the arc discharge energy generated in the IGBTs 61 and 62 is consumed by introducing the energy to the fuse 67 through the semiconductor element 66. Therefore, the secondary failure of the accident caused by the break of the open IGBTs 61 and 62 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a power converter that converts DC into AC or vice versa using a modular semiconductor device such as an IGBT or a power transistor.

[0002]

2. Description of the Related Art In recent years, GTO and IG have been used in electric vehicle control devices.
Power converters such as inverters and converters using semiconductor switching elements such as BTs and power transistors are frequently used. Among them, in a power converter using a module-type semiconductor switching element such as an IGBT or a power transistor, for example, in an electric car using an inverter, an excessive current generated at the time of a power supply short-circuit accident such as an inverter phase short-circuit causes a solder connection in the module. The part is peeled off, and the semiconductor switching element often causes an open failure. The phase short-circuit current, which is the cause of this open-circuit failure, can be tens of thousands to hundreds of thousands of amps, and when the solder joint is opened, the damage caused by accidents such as damage to peripheral devices due to arc discharge or fire may occur. It becomes a problem.

As one of the solutions, a high-speed fuse has been conventionally inserted into each phase arm of an inverter as described in Japanese Patent Application Laid-Open No. 3-78432. This high-speed fuse is for preventing the outer wall of a module element from being ruptured due to element damage due to a power supply short-circuit or the like, and describes an increase in wiring inductance due to high-speed fuse connection and installation of a snubber therefor.

[0004]

In the above-mentioned prior art, a large-capacity high-speed fuse having a current-carrying capacity is required, and this fuse is relatively expensive. Problems such as an increase in the wiring inductance and an increase in the snubber of the semiconductor switching element and an increase in loss due to the snubber may increase the cost of the power converter and deteriorate the conversion efficiency.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide, in a power converter using a modular semiconductor device, a simple protection device against accidental damage and damage caused by open breakage of the modular semiconductor device caused by a power supply short circuit accident or the like. It is an object of the present invention to prevent the power converter as a whole from increasing in cost and lowering in conversion efficiency.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to connect a module type semiconductor element connected in series as an upper and lower arm for one phase to both ends of a DC power supply, and to provide an AC output terminal at a serial connection point of the element. In the power converter, a protection device is provided at both ends of the series-connected modular semiconductor elements, in which a series connection of a semiconductor element and a fuse, which are brought into conduction by breakdown or breakover at a predetermined voltage or higher, is connected in parallel. Is achieved by Further, an object of the present invention is to provide a power converter in which a module type semiconductor element connected in series as an upper and lower arm for one phase is connected to both ends of a DC power supply and an AC output terminal is provided at a serial connection point of the element. At both ends of the module-type semiconductor element connected in series, a protection device is provided in which a series connection of a thyristor element and a fuse, which are controlled to be fired by an abnormal voltage when an open fault occurs due to an excessive current of the module-type semiconductor element, is connected in parallel. Is achieved by

[0007]

FIG. 1 shows an embodiment of the present invention, in which a protection device in a power converter using a modular semiconductor element is applied to a two-level inverter type electric vehicle.

Reference numeral 1 denotes a pantograph for supplying electric power to an electric vehicle from an overhead line connected to a DC power supply (not shown), 2 denotes a disconnector, 3 denotes a charging resistance (or reduction resistance) to a next-stage filter circuit, and 4 denotes It is a high speed circuit breaker. Numeral 5 denotes a reactor of the filter circuit, which constitutes an LC filter with capacitors divided and installed in each phase described later. Reference numerals 6, 7, and 8 configure a power converter of a two-level three-phase inverter that switches a module type semiconductor element by a PWM control circuit (not shown) to convert DC to three-phase AC of two-level potential or vice versa. This corresponds to each of the U-phase, V-phase, and W-phase converters, and a specific circuit thereof is shown in the U-phase converter 6.

Reference numerals 61 and 62 denote IGBTs of modular semiconductor elements constituting upper and lower arms of a two-level inverter;
63 is a filter capacitor divided for each phase.
Normally, the overhead line voltage is charged in the capacitor 63,
It becomes the power supply voltage in the phase converter 6. It is the same that the filter capacitor voltages become the respective power supply voltages in the V phase and the W phase, respectively. Reference numerals 64 and 65 denote wiring inductances and the like that are generated when the IGBT and the filter capacitor are connected to form a converter.

Here, 66 and 67 are parts related to the present invention, 66 is a semiconductor element which becomes conductive by breaking over or breaking down at a predetermined voltage, and 67 is a fuse. These are connected in series, and the series body is connected in parallel to both ends of the IGBTs 61 and 62 connected in series.

Reference numeral 68 denotes an IGBT 6 connected in series.
A U-phase AC output terminal connected to the connection points 1 and 62,
The other V-phase and W-phase AC output terminals 78 and 88 are connected to a three-phase induction motor (not shown) which is an inverter load.

Now, in the inverter-type electric vehicle configured as described above, the upper and lower arms IGBTs 61 and 62 of the U-phase converter 6 due to, for example, noise malfunction or damage to one element.
When both become conductive, the filter capacitor 63
Power supply short circuit accident.

The U-phase filter capacitor 6
3 is connected to another V through wiring inductances 64 and 65.
Phase, W phase. Generally, the wiring inductance in each phase is as small as several μH or less, so that the power supply short-circuit of the U-phase filter capacitor immediately develops into a power supply short-circuit accident that also short-circuits the V-phase and W-phase filter capacitors. Therefore, the U-phase vertical arm I
The power supply short-circuit current flowing through the GBTs 61 and 62 is several hundred thousand to several hundred thousand A in an electric vehicle having a high overhead line voltage.
The solder connection in the BT module is peeled off,
The element often suffers from an open fault. Since arc discharge is caused when the solder connection is opened, peripheral devices may be damaged or a fire may cause damages due to an accident. For this reason, conventionally, as described above, it has been proposed to insert a fuse into the arm of each phase of the inverter to prevent an open failure due to element damage. However, since a normal current flows, the fuse has a predetermined current capacity. However, there is a problem that the cost is increased due to the necessity, and the snubber of the element has to be strengthened due to an increase in the wiring inductance due to the mounting of the fuse.
The present invention, as in the conventional example described above, is unavoidable in that an open failure due to element damage is unavoidable, and prevents accidents such as damage to peripheral devices and fire due to arc discharge occurring at the time of the open failure.

Next, the operation and operation of the invention unit in the embodiment of FIG. 1 will be described. U-phase upper and lower arm IGBT6
When the power supply circuits 1 and 62 become conductive due to noise malfunction or the like, a power supply short-circuit current of several hundred thousand to several hundred thousand A flows as described above, and the energy due to the power supply short-circuit current flows through the wiring inductances 64 and 65. Stored. on the other hand,
In the modules of the IGBTs 61 and 62 in which the power supply short-circuit current is flowing, the Joule heat due to the excessive current peels off the solder connection portion, and these IGBT elements are subjected to open failure. The open state of the IGBT element (61 or 62 alone or both 61 and 62) forcibly cuts off the above-mentioned power supply short-circuit current, and accumulates in the wiring inductances 64 and 65 between the open terminals. An arc discharge is caused by the applied energy. Even if the wiring inductance is small, this arc discharge energy is enormous because the power supply short-circuit current is very large, hundreds of thousands to hundreds of thousands of amps, and the module explodes, causing spillover to peripheral devices. It is.

The embodiment of the present invention shown in FIG. 1 utilizes the fact that an abnormal voltage is generated due to the above-mentioned arc discharge. I open
By inserting a fuse 67 in parallel with the GBTs 61 and 62, the occurrence of the arc discharge is suppressed, and the energy stored in the wiring inductance is consumed by the fuse 67.

That is, the arc discharge energy of the IGBT element having an open fault is shunted to the series circuit of the semiconductor element 66 and the fuse 67 which are brought into conduction by the abnormal voltage. When the opening of the IGBT element breakage progressed and all the arc discharge energy was soon commutated to the series circuit,
The opening operation and the arc discharge of the IGBT element breakage are stopped. In the fuse 67 in which all of the arc discharge energy has been commutated, the energy consumption in the fuse so far is added, and when the value exceeds the i ² t resistance of the fuse 67, the fuse 67 starts to be blown. By consuming discharge energy in the fuse,
Arc discharge at the fuse 67 itself is prevented. With the above operation and action, it is possible to prevent the accident spillover damage due to the IGBT element opening damage.

Depending on the open state of the damaged portion of the IGBT element, that is, the open terminal distance, arc discharge may occur due to the voltage (in most cases, the filter capacitor voltage) applied between the open terminals after the fuse is blown. However, since the arc discharge energy in this case is an open state without a power supply short-circuit state before it, it is smaller than the arc discharge energy due to the power supply short-circuit current,
Not enough to burst the module. In addition, when a power supply short circuit occurs, other existing protection devices also act to cut off the circuit and discharge the filter capacitor voltage.
Even if an arc discharge occurs after the fuse is blown, it is automatically protected.

Since no current flows in the semiconductor element 66 and the fuse 67 in the embodiment of FIG. 1 during normal operation of the inverter, a small-capacity and inexpensive device can be used. There is such a feature that the wiring inductance does not increase and the loss does not increase. The semiconductor element 66 uses a so-called breakover element as an element that becomes conductive by breaking over at a predetermined voltage, or uses a diode as an element that breaks down at a predetermined voltage and becomes conductive. The capacity is selected to be equal to or higher than the maximum peak voltage normally applied to the elements constituting the arm of the inverter.

According to the embodiment of the present invention shown in FIG. 1 described above, in a power converter using a modular semiconductor device, an accident due to open breakage of the modular semiconductor switching device, which occurs when a power supply short circuit occurs or the like. It is possible to realize a protection device with a simple configuration against the ripple damage, and there is an effect of preventing the power converter including the protection device without increasing the cost and lowering the conversion efficiency.

FIG. 2 is a block diagram of another embodiment of the present invention showing a power converter using a modular semiconductor device and a protection device therefor. The difference from the embodiment of FIG. 1 is that a fuse provided in each phase (U, V, W) converter is replaced by a fuse provided in each phase (U, V, W).
V, W). It is to be noted that all the other symbols indicate the same elements as those in the embodiment of FIG. That is, one end of each of the semiconductor elements 66, 76, and 86 that are brought into conduction by breaking down or breaking over at a predetermined voltage or more is connected to one end of the module type semiconductor element IGBT connected in series for each of U, V, and W phases. One end of a common fuse 9 is connected to the other end of the semiconductor element, and the other end of the fuse 9 is connected to the other end of a modular semiconductor element connected in series. For example, in the case of a U-phase power short-circuit accident, the operation described in detail in the embodiment of FIG. 1 is performed by the series connection circuit of the semiconductor element 66 and the fuse 9 to suppress the arc discharge of the IGBT having the open failure. It also prevents the spread of accidents such as damage to peripheral devices and fire.

According to another embodiment of the present invention shown in FIG.
In the embodiment of FIG. 1, the fuses provided in each phase (U, V, W) converter are collectively provided in each phase (U, V, W).
There is an effect that the cost of the protection device in the power converter using the module type semiconductor element can be further reduced.

FIG. 3 is a block diagram showing a power converter using a module type semiconductor device and its protection device according to another embodiment of the present invention. The difference from the embodiments of FIGS. 1 and 2 is that a semiconductor element connected in series to a fuse is replaced with a thyristor element, and a control circuit for turning on the thyristor element is provided. That is, in the example, 661
Is a thyristor element, 69 is a control circuit of the thyristor 661, and the control circuit 69 is composed of the abnormal voltage detector 691
It is composed of 92 thyristor element gate circuits. In addition,
All other symbols indicate the same elements as in the embodiment of FIG. This embodiment is different from the IGBT 6 in the power supply short circuit accident.
An abnormal voltage generated at the time of the open failure of the abnormal voltage detectors 1 and 62 is detected by the abnormal voltage detector 691, and the output of the abnormal voltage detector 691 drives the thyristor element gate circuit 692 to turn on the thyristor element 661, that is, to make the thyristor element 661 conductive. , A series circuit of a thyristor element 661 and a fuse 67, and the IG with an open fault is operated by the operation described in detail in the embodiment of FIG.
The purpose of the present invention is to suppress the arc discharge of the BT and prevent the spread of accidents such as damage to peripheral devices and fire.

The abnormal voltage detector 691 is configured to detect an abnormal voltage after the power supply is short-circuited, that is, the voltage across the abnormal voltage detector becomes almost zero due to the power supply short-circuit, and thereafter an abnormal voltage caused by an element open failure. . Therefore,
Unlike the case of the embodiment of FIG. 1, the detection of the abnormal voltage is performed as follows.
It can be arbitrarily selected without being influenced by the maximum peak voltage normally applied to the semiconductor element constituting the arm, and the abnormal voltage can be detected at a lower voltage value. There is an effect that the suppression can be reliably performed in a lower energy state.

FIG. 4 is a block diagram showing a power converter using a module type semiconductor device and a protection device therefor according to another embodiment of the present invention. The difference from the embodiment of FIG.
The fuse provided in the (U, V, W) converter is connected to each phase (U, V, W).
V, W). It is to be noted that all the other symbols indicate the same elements as those in the embodiment of FIG. That is, a thyristor element 66 of each phase is connected to one end of a series-connected module type semiconductor element IGBT of U, V, W phases.
1, 761, 861 are connected to one end, and the other end of the thyristor element is connected to one end of a common fuse 9,
The other end of the fuse 9 is connected to the other end of the module type semiconductor element connected in series. For example, in the event of a U-phase power short-circuit, the operation described in detail in the embodiment of FIG. 3 is performed by the series connection circuit of the thyristor element 661 and the fuse 9 to suppress the arc discharge of the IGBT having the open failure. It also prevents the spread of accidents such as damage to peripheral devices and fire. According to this embodiment, the fuse provided for each phase (U, V, W) in the embodiment of FIG.
V, W), there is an effect that the cost of the protection device in the power converter using the modular semiconductor element can be reduced.

Although the embodiment of the present invention has been described with reference to a case in which the two-level inverter circuit has one arm element, the present invention is not limited to this case. Also, the present invention can be applied to an inverter circuit or the like for converting a direct current into a three-level alternating current.

Although the embodiment of the present invention has been described with reference to the case where the filter capacitors are separately provided for each phase, the present invention is also applicable to the case where the filter capacitors are provided collectively for each phase.

[0027]

According to the present invention described above, in a power converter using a modular semiconductor device, breakover or breakage due to an abnormal voltage of arc discharge occurring when the modular semiconductor device is opened and damaged due to a power supply short circuit accident. By providing a series body of a semiconductor element and a fuse that breaks down, or a series body of a semiconductor switching element and a fuse that is ignited at the detector output of the abnormal voltage, between the series semiconductor element terminals that cause a power supply short circuit, Since a protection device against accident and damage caused by open breakage of the modular semiconductor element can be realized with a simple configuration, it is not necessary to strengthen a snubber or the like, and it is possible to prevent an increase in the cost of the entire power converter. At the same time, since no current flows through the protection device during normal operation of the power converter, an effect is obtained that a reduction in conversion efficiency can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a protection device for a modular semiconductor device power converter according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a protection device for a modular semiconductor device power converter according to another embodiment of the present invention.

FIG. 3 is a configuration diagram of a protection device for a modular semiconductor device power converter according to another embodiment of the present invention.

FIG. 4 is a configuration diagram of a protection device for a modular semiconductor device power converter according to another embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pantograph, 2 ... Disconnector, 3 ... Charge resistance, 4 ... High-speed circuit breaker, 5 ... Filter reactor, 6, 7, 8 ... U
Phase, V phase, W phase converter, 9, 67 ... fuse, 61, 6
2: Module type semiconductor element (IGBT), 63: U-phase filter capacitor, 64, 65: Wiring inductance, 66, 76, 86: Semiconductor element (breakover element or diode), 68, 78, 88: U-phase, V
Phase, W phase AC output terminal.

Continued on front page F-term (reference) 5G053 AA03 AA04 AA09 AA14 CA03 EB01 EC05 EC06 FA05 5H007 CA01 CB05 CC07 FA03 FA06 FA13 FA19 5H740 BA11 BB05 BB08 BC01 BC02 MM12

Claims (4)

[Claims] 1. A power converter having a module type semiconductor element connected in series as an upper and lower arm for one phase connected to both ends of a DC power supply, and having an AC output terminal at a serial connection point of the elements. A protection device for a power converter, wherein a series body of a semiconductor element and a fuse which are brought into conduction by breaking down or breaking over at a predetermined voltage or more is connected in parallel to both ends of the modular semiconductor element. 2. A power converter in which a plurality of converters having an AC output terminal connected to a series connection point of a series connection of a plurality of converters are connected to both ends of a DC power supply. In one embodiment, one end of each of the series-connected modular semiconductor elements is connected to one end of a semiconductor element that is brought into a conductive state by breaking down or breaking over at a predetermined voltage or more, and An electric power characterized in that one end of a common fuse is connected to the other end of the semiconductor element which is turned on and becomes conductive, and the other end of the fuse is connected to the other end of the serially connected modular semiconductor element. Transducer protection device. 3. A power converter in which a module type semiconductor element connected in series as an upper and lower arm for one phase is connected to both ends of a DC power supply and an AC output terminal is provided at a serial connection point of the elements. A power converter, wherein a series body of a thyristor element and a fuse that is controlled to be fired by an abnormal voltage when an open fault occurs due to an excessive current of the module semiconductor element is connected in parallel to both ends of the modular semiconductor element. Protection device. 4. A power converter in which module type semiconductor elements connected in series as upper and lower arms for one phase are connected, and a plurality of converters having an AC output terminal at a serial connection point of the elements are connected to both ends of a DC power supply. One end of a thyristor element that is controlled to be fired at an abnormal voltage when an open fault occurs due to an excessive current of the module type semiconductor element is connected to one end of the module type semiconductor element connected in series in each phase, respectively. Wherein one end of a common fuse is connected to the other end of each of the thyristor elements, and the other end of the fuse is connected to the other end of the modular semiconductor element connected in series. apparatus.