JPH066983A - Inverter unit - Google Patents

Abstract

PURPOSE:To provide an inverter unit comprising a self-extinguishing module in which transient overvoltage can be suppressed through a simple circuitry. CONSTITUTION:Snubber circuits TXs, each comprising a parallel circuit of one resistor and one diode connected in series with one capacitor, and self- extinguishing modules TMs are arranged, at short intervals, on conductor frames FRP, FRN. The snubber circuits TXs and the self-extinguishing modules TMs are arranged symmetrically with respect to a plane normal to the conductor frames while including the intermediate points thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverse converter which receives power from a DC power source and uses a self-extinguishing element to generate AC power of a predetermined frequency.

[0002]

2. Description of the Related Art In general, an inverse conversion device of this type employs a circuit configuration using a self-arc-extinguishing element. In particular,
In recent years, power transistors or FET devices with high output and fast switching speed have been produced and put into practical use. However, when commutation or overload cutoff of these elements is accompanied by a strong transition voltage or current, they often exceed the safe allowable range for the operation of these elements, and not only damage the elements, but also the surrounding environment. Also, the circuit element of is damaged, rendering the inverse conversion device itself unusable.

Among the inverse converters of this type, a device for converting a medium power (a device having a capacity of 20 kVA to 100 kVA) usually provides a relatively simple solution to the above-mentioned suppression of transient overvoltage generation. ing. Here is a brief overview of the device and its countermeasures.

As shown in FIG. 1, an inverse converter I of this kind is shown.
The NT is often used in combination with the forward conversion device CVT. In the present invention, for convenience, three-phase AC power is introduced into the forward conversion device CVT from the generator M mounted on the power unit of the ship via the input end T1. The DC output voltage from the forward converter CVT is introduced into the reverse converter INT via the positive and negative buses L _{P and} L _N. And this inverse converter I
The three-phase output power of NT is used from the output end T2 as a power supply for a required power supply unit, for example, a lighting device in a ship or an inboard device.

The reverse of converting DC power into three-phase AC power
In the converter INT, each phase U, V, W is paired
Arranged, self-extinguishing elements, eg transistors
Tr _1,Tr₂Transistor module TM consisting of_1,
TM_2,TM₃Is converted to a square wave by. in this case,
A transistor Tr is provided by a phase control circuit (not shown).
_1,Tr₂Corresponding control signal to control the switching time of
Base B_u1,B_l1Applied to the above conversion to
Register Module TM_1,TM_2,TM₃The corresponding output of
Powerful O₁Etc., the electric power of each phase U, V, W is obtained. Also, must
If necessary, square waves such as these can be used, for example, in the pulse width modulation method.
Transistor module TM that can be converted into an appropriate sine wave, etc._1,TM_2,TM₃Is usually
In case of, frame FR made of conductive material according to current voltage
_P,FR_NMounted on top of. And the forward conversion device CVT
The electric power rectified by is the feeding point S of the forward converter CVT._P,S
_NTo bus L_P,L_NPower receiving point M via_P,M_NReach
It

In the power supply device having the above configuration, a transition transient voltage (so-called kickback voltage) is generated when the transistors Tr _{1 and} Tr ₂ are commutated and the overload is cut off. Then, beyond the reverse bias safe area (RBSOA), the transistors Tr _{1 and} Tr ₂ are damaged. To prevent this, for example, a simple snubber circuit consisting of a resistor, a capacitor and a diode may be inserted between the collector and emitter of each transistor Tr ₁ or Tr ₂ (eg Eisuke Masada,
Amano Hitoo supervision, latest power device utilization reader, Ohmsha, June 1988, see page 15), or
Insert a current limiting reactor (not shown) into the busbars L _{P and} L _N ,
A freewheel die (not shown) is connected in parallel to both ends of this reactor (for example, Eisuke Masada, supervised Amano Hitoo, latest power device utilization reader, Ohmsha,
The transient transition voltage is suppressed by the method described in June 1988, page 17). This type of measure requires a considerable mounting space because the size and weight of each element are large. Moreover, this leads to an unwanted increase in stray capacitance or inductive inductance, which even adversely affects the dynamic characteristics of the circuit.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned difficulties and to have a simple circuit configuration which can suppress the occurrence of transient overvoltage due to a self-extinguishing type switching element and which occupies a small space. Therefore, it is an object of the invention to provide an inverse converter of the kind mentioned at the outset, which makes it possible to reduce manufacturing and maintenance costs significantly, and is stable and reliable in operation.

[0008]

SUMMARY OF THE INVENTION According to the invention, the above-mentioned problem is solved in the case of an inverse converter of the type mentioned at the outset by parallel conductor frames FR _P, F for the positive and negative potentials of the inverse converter INT.
At least two self-extinguishing elements T on R _N
A plurality of self-extinguishing element modules TM formed by connecting r _{1 and} Tr ₂ in series, one resistor R and one diode D
At least one snubber circuit TX formed by connecting one capacitor C in series to the parallel circuit formed by the above, and including a midpoint between the conductor frames FR _{P and} FR _N , The self-extinguishing element module TM and the snubber circuit TX are arranged symmetrically with respect to a plane perpendicular to the frames FR _{P and} FR _N , and the forward direction of the diode D is negative from the positive potential conductor frame FR _P. Conductor frame F of electric potential
The power supply point S of the DC power supply CVT is arranged so as to face R _N.
This is solved by the fact that power receiving points M _{P and} M _N corresponding to _{P and} S _N are provided near the intermediate points of the conductor frames FR _{P and} FR _{N ,} respectively.

Further advantageous configurations according to the invention are described in the dependent claims.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail with reference to the drawings showing the embodiments. In this case, if the reference numerals used in the following drawings have the same functions as those in FIG. 1, the same reference numerals are used. Further, reference numerals of members having the same function in circuit configuration and not necessary for direct explanation are omitted for simplicity.

FIG. 2 shows a self-extinguishing type switching element.
4 snubbers to suppress transient overvoltage
Circuit TX_1,TX_2,TX_3,TX_FourPositive and negative conductor frame FR
_P,FR_NHand over between each self-extinguishing element module
TM_1,TM_2,TM₃It is arranged adjacent to. In that case,
Of particular importance is the stray capacitance or inductance between lines or components.
In order to avoid the increase of conductive load, the length of the line and the
Distance between parts, snubber circuit TX_1,TX_2,TX_3,T
X_FourAnd self-extinguishing element module TM_1,TM_2,TM₃of
The distance between them is shortened, and these parts are connected to the conductor frame.
FR_P,FR_NNeed to be symmetrically arranged above. Furthermore, in order
Both feed points S of converter CVT or DC power supply_P,S_NKarasou
Bus line L_P,L_NInversion device I introduced via
NT positive and negative conductor frame FR_P,FR_NReceiving point M in_P,
M_NIs the conductor frame FR _P,FR_NThe heart of the
In the case of FIG. 2, three self-extinguishing element modules TM_1,
TM_2,TM₃Module TM in the center of₂Placed at
To do. 2 and 4, the power receiving point M is shown for convenience of explanation.
_P,M_NIs the module TM₂Shown offset from the connection point
is there.

In practice, it is difficult to dispose the power receiving points M _{P and} M _N completely in the centers of the positive and negative conductor frames FR _{P and} FR _N due to the arrangement of components and the thickness and flexibility of the busbars. It is desirable to provide the module as close to the central module TM ₂ as possible.

The snubber circuits TX _1, TX _2, TX _3, TX ₄ are
As shown in FIG. 3, it has a circuit configuration known per se.
That is, the resistor R and the diode D are connected to the positive terminal P connected to the positive conductor frame FR _P at one end of the parallel circuit, the other end is connected to the capacitor C, and the negative terminal N is connected in series. In this case, it is necessary to direct the diode in the forward direction or from the positive terminal P to the negative terminal N.

Resistor R, capacitor C and diode D
Regarding the withstand voltage and the capacitance, the optimum values should be obtained experimentally, but the following formulas can be used as a guide. That is, regarding the capacitor C,

[0015]

[Outer 1]

Where L: DC main circuit inductance, V _CP : switching element withstand voltage, E: DC main circuit voltage, I ₀ : overload breaking current.

Regarding the resistance R,

[0018]

[Outside 2]

Here, K: a constant, (ripple current frequency on the DC bus) 400 Hz> 1.0 400 Hz <3.0, f: current frequency when overload is cut off.

As the diode D, a diode having a withstand current surge of one third of the overcurrent interruption value of the device and a withstand voltage equivalent to that of a switching element is used. The circuit shown in FIG. 4 can be used as another configuration for eliminating the transient overvoltage at the time of commutation by the self-extinguishing element modules TM _1, TM _2, TM ₃ . In this case, a commutation diode D _P is connected in parallel with a positive bus L _P that connects the positive feeding point S _P of the forward converter CVT to the positive power receiving point M _P of the inverse converter INT.
This parallel connection is directly made between the positive feeding point S _P and the positive receiving point M _P via the conducting line L _P ′ connected to both ends of the diode, and the bus line L _P includes a reactance component such as a reactor. Circuit element is not inserted. The forward direction of the diode D _P is from the positive power receiving point M _P to the positive power feeding point S _P as illustrated. Regarding the withstand voltage and the capacitance of the diode D _P , the optimum values should be experimentally obtained. For example, the rated load current i _{0 and the} rated output voltage v _{0 are set.}
On the other hand, a diode having a breakdown voltage = 3 v ₀ and a current value = 2 i ₀ should be used. Generally, when the frequency of the output AC voltage is high, fast diodes should be used.
In the case of commercial power supply, that is, 50 to 60 Hz, ordinary diodes are sufficiently effective.

In FIG. 4, one of the bus lines L _{P and} L _N , that is, L
Although the commutation diode D _P as described above toward the _P connected in parallel, the other, i.e. L may be connected towards the _N, also both, i.e. busbars L _P, L respectively rolling on the _N flow diode D _P
May be connected in parallel. Even when connected to the L _N side, the forward direction of the diode D _P should be opposite to the direction of the steady current flowing through the bus.

To examine the effect of the present invention, FIG.
A realization consisting of a corresponding forward converter CVT and an inverse converter INT.
An experiment was performed with the device at that time. In this experiment, self-extinguishing element
Child module TM_1,TM_2,TM₃Manufactured by Sansha Electric Co., Ltd.
Transistor module, SQD300 BA 60 is used.
Bus L_P,L_NInsert one breaker between the
Bus L_PConnect one meter shunt resistor to
A current transformer was inserted into this bus bar to measure the transient current.
Also, insert a breaker at the output end to shorten the three-phase load output end.
I was entangled. With the breaker on the output side open,
After activating the device of the body, from the stable state,
Close the breaker, conductor frame FR _P,FR_NBetween
Applying an oscilloscope probe to the transistor commutation
Directly measure the transient voltage of the
Was measured with the current transformer.

The three-phase sine AC input to the forward converter CVT is
At 205 V rms, the frequency was 40 to 120 Hz, the output was a three-phase square wave, the voltage was 225 V rms, and the frequency was constant at 60 Hz. The snubber circuit used has the circuit configuration shown in FIG.
= 1.5Ω / 5W (Metal oxide resistance), C = 3μF / 630V
(Metalized polypropylene film capacitor), D: ER
D 27-10 (manufactured by Fuji Electric Co., Ltd.) was used. As the commutation diode D _P in FIG. 4, FRS 200 BA 60 manufactured by Sansha Electric Co., Ltd. was used.

For comparison, four snubber circuits TX _{1 and} TX
FIG. 5 shows switching characteristics when _2, TX _{3 and} TX ₄ are each formed of only one capacitor C and symmetrically arranged as shown in FIG.

Four snubber circuits TX _1, TX _2, TX _3, TX
FIG. 6 shows the switching characteristics when ₄ is formed by three circuit elements R, C, and D of the same type and arranged as shown in FIG.

Only one commutation diode D _P shown in FIG. 4 is connected in parallel to the bus line L _P , and four snubber circuits TX _{1 and} TX are provided.
FIG. 7 shows switching characteristics when _2, TX _{3 and} TX ₄ are each formed of only one capacitor C and symmetrically arranged as shown in FIG.

One commutation diode D _P is connected in parallel to the bus L _P, and at the same time, four snubber circuits TX _1, T shown in FIG.
FIG. 8 shows switching characteristics when X _2, TX _{3 and} TX ₄ are combined and arranged as shown in FIG.

In addition to the arrangement shown in FIG. 4, commutation diodes are connected in parallel to the return bus line L _N , and at the same time, four snubber circuits TX _1, TX _2, TX _3, TX ₄ shown in FIG. FIG. 9 shows the switching characteristics in the case of such arrangement.

Each of FIGS. 5 to 9 was measured under the same conditions. One scale on the horizontal axis was 100 μs, and one scale on the vertical axis was 200 V for output voltage V _{0 and} 250 A for current I ₀ . Is. The closing time of the breaker for short circuit is α.

As is apparent from FIG. 5, in the simplest snubber circuit with only one capacitor, 75 μs after the closing time α.
At this point, the transistor starts switching substantially, and then the voltage and current both show a remarkable oscillating waveform. This oscillation is due to the effective resonant circuit consisting of the capacitor C used to damp this transient voltage and the inductive reactance in the circuit. Also, a significant reverse current due to the delay in the commutation of the transistor occurs at 75 μs after the closing time α (denoted by the symbol β in the figure). The maximum and minimum values of the output voltage V ₀ in this measurement are 660 V and 60 V, respectively, and this transistor's reverse bias safe area (RBSO
It is separated from A) (note that in the configuration of FIG. 1 in which the capacitor C is not used and there is no snubber circuit, the transistor module is definitely damaged and cannot be used). Of course, there is a possibility that the safety region may be easily exceeded due to the load or the voltage used, and such a snubber circuit with only the capacitor C is a very dangerous device that lacks reliability.

In FIG. 6, 75 μ after the breaker closing time α
It is possible to completely dampen the significant vibrations appearing in s,
The maximum and minimum output voltage V ₀ is 620 V and
It became 244V.

In FIG. 7, 75 μ after the breaker closing time α
The reverse current appearing at s is completely blocked by the commutation diode D _P. However, the vibration phenomenon that occurred in FIG. 6 can be seen again. The maximum and minimum values of the output voltage V ₀ were 636 V and 92 V, respectively.

In FIG. 8, 75 μ after the breaker closing time α
The reverse current appearing at s is blocked by the commutation diode D _P , and the oscillation phenomenon shown in FIG. 6 is completely eliminated. The maximum and minimum values of the output voltage V ₀ were 548 V and 268 V, respectively.

In FIG. 9, the maximum and minimum values of the transient output voltage V ₀ are 516 V and 260 V, respectively. When these results are comprehensively evaluated, a snubber circuit TX _1, TX _2, TX _{3, including} a capacitor C, a resistor R, and a diode D is obtained _.
TX ₄ is arranged symmetrically with respect to the transistor modules TM _1, TM _2, TM ₃ on the conductor frames FR _P, FR _N , and one commutation diode D _P, is arranged in parallel with each of the bus lines L _P, L _N.
It can be seen that the connection of D _N most effectively suppresses the transient voltage and current.

Although the above description has been made with respect to the three-phase output voltage, it should be noted that the circuit arrangement of the present invention can be applied to the power supply device having a single-phase output voltage in exactly the same technical concept. Further, according to the present invention, the snubber circuit TX attached to the transistor module TM is connected to the conductor frame FR _P, F.
Including the power receiving points M _{P and} M _N above R _N , the conductor frame FR _P,
It is important to arrange symmetrically with respect to a plane perpendicular to FR _N , and other modifications than the arrangement shown in FIG. 2 are shown in FIGS.

10A, 10B, and 10C show the case of the inverse converter of the three-phase AC power supply, in which the transistor module TM is used.
Two, three, and three snubber circuits TX are arranged symmetrically on the conductor frames FR _P, FR _N for _1, TM _2, TM ₃ , respectively. Snubber circuit TX _{2 of} FIG. 10B
Are arranged above or below the transistor module TM ₂ . In FIG. C, which snubber circuit TX _1, T
X _{2 and} TX ₃ are also corresponding transistor modules TM _1,
The layers are arranged above or below TM _{2 and} TM ₃ .

In FIG. 11, in order to increase the output current capacity of the inverse converter, the transistor modules TM _{1 and} TM of each phase are added.
Transistor module T in parallel with _2, TM ₃
It is reinforced by adding M ₁ ′ _, TM ₂ ′ _and TM ₃ ′. Even in this case, the snubber circuits TX _{1 to} TX ₇ are arranged on the conductor frames FR _{P and} FR _N on each pair of transistor modules TM _1, TM ₁ ′ _, TM _2, TM ₂ ′ _, TM _3, TM ₃ ′.
They are arranged symmetrically with respect to.

[0038] Figure 12A, B, In C, respectively in the case of the inverters of single-phase power supply, when regarded as a single-phase two-phase for each phase of the transistor module TM _1, TM ₂ 1
The number of snubber circuits TX is 2, 3, and symmetrically arranged on the conductor frames FR _P, FR _N.

In FIGS. 13A and 13B, the output current of the inverse converter is shown.
Each transistor module TM to increase capacity_1,T
M₂And the same type of transistor module TM
₁′ _,TM₂′ Is added in parallel. in this case
But snubber circuit TX₁~ TX₃Is each pair of transistors
Module TM_1,TM₁′_,TM_2,TM₂For ′
Conductor frame FR_P,FR_NAre placed on top of.

Further, although not shown in the above drawing, FIG.
The so-called hybrid module can be obtained by directly embedding the snubber circuit shown in 1 above in the transistor module TM and molding and molding it with, for example, a curable plastic resin. With such a configuration, the installation space can be reduced, and these hybrid modules are arranged at equal intervals on the conductor frames FR _P, FR _N without special consideration regarding the symmetrical arrangement described above. Just by doing, the symmetrical arrangement can be realized automatically. of course,
Such a molding method can also be applied to two or more transistor modules TM arranged in parallel for each phase in order to reinforce the output current capacity. Further, such a composite modularization can be extremely advantageously used even when used in a ship or in the rain, even under a bad external environment, and under conditions such as heat resistance, humidity resistance and salt damage. .

As described above, it is easy for those skilled in the art to modify or improve the contents of the present invention by various methods.
It goes without saying that any device defined in the claims belongs to the scope of the present invention.

[0042]

As described above, according to the present invention,
With a very simple structure, the transient voltage and current during commutation of the inverse converter can be reduced to appropriate values, and damage to active elements such as output transistors or FETs can be prevented. Therefore, the device has a very compact structure and can be manufactured and maintained at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing a general circuit configuration of a three-phase AC output power supply device including an inverse conversion device.

FIG. 2 is a block diagram of a three-phase AC output power supply device in which a snubber circuit is symmetrically arranged in the vicinity of a self-extinguishing element.

FIG. 3 is a circuit diagram showing a configuration of a snubber circuit used in FIG.

FIG. 4 is a block diagram of a three-phase AC output power supply device in the case where a commutation diode is inserted in one of the bus bars between the forward converter and the inverse converter.

FIG. 5 is a graph showing switching characteristics of a three-phase AC output power supply device (when only a single capacitor is used as a snubber circuit and the circuit arrangement of FIG. 2 is used).

FIG. 6 is a graph showing switching characteristics of a three-phase AC output power supply device (when the circuit of FIG. 3 is used as a snubber circuit and the circuit arrangement of FIG. 2 is used).

FIG. 7 is a graph showing switching characteristics of a three-phase AC output power supply device (the circuit arrangement of FIG. 4 using a commutation diode is further used in the circuit arrangement of FIG. 2 and only a single capacitor is used in each snubber circuit). if you did this).

8 is a graph showing a switching characteristic of a three-phase AC output power supply device (when the snubber circuit in the case of FIG. 7 is configured by the method of FIG. 3).

FIG. 9 is a graph showing switching characteristics of a three-phase AC output power supply device (in addition to the arrangement in the case of FIG. 8, a commutation diode is further inserted in the return bus).

FIG. 10 is a circuit diagram showing the arrangement of another snubber circuit used in the inverse conversion device for a three-phase output power supply.

FIG. 11 is a circuit diagram showing the arrangement of another snubber circuit used in the inverse conversion device for a three-phase output power supply having a large current capacity.

FIG. 12 is a circuit diagram showing an arrangement of another snubber circuit used in the inverse converter of the single-phase output power supply.

FIG. 13 is a circuit diagram showing the arrangement of another snubber circuit used in the inverse conversion device for a single-phase output power supply having a large current capacity.

[Explanation of symbols]

CVT Forward converter INT Inverting converter M Generator T ₁ Input end T ₂ Output end L _P, L _N Bus S _P, S _N Feeding point M _P, M _N Receiving point FR _P, FR _N Conductor frame D _p Commutation Diodes TM _1, TM _2, TM _3, TM ₁ ′ _, TM ₂ ′ _, TM ₃ ′ Modules of self-extinguishing element TX _1, TX _2, TX _3, TX _4, TX _5, TX _6, TX ₇ Snubber circuit

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 22, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

In FIG. 7, 75 μ after the breaker closing time α
The reverse current represented by s is completely blocked by the commutation diode D _p . However, the vibration phenomenon generated in FIG. 5 can be seen again. Maximum and minimum values of the output voltage _{V o} has become 636V and 268V, respectively.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

In FIG. 8, 75 μ after the breaker closing time α
The reverse current represented by s is completely blocked by the commutation diode D _p . Moreover, the vibration phenomenon generated in FIG. 5 is completely removed. Maximum and minimum values of the output voltage _{V o} has become 548V and 268V, respectively.

Claims (2)

[Claims] 1. In a reverse conversion device which receives power from a DC power supply and generates AC power of a predetermined frequency by using a self-extinguishing element, parallel conductor frames FR _P, FR for positive and negative potentials of the reverse conversion device INT. _{On N} , at least 2 each
A plurality of self-extinguishing element modules TM in which a plurality of self-extinguishing elements Tr _{1 and} Tr ₂ are connected in series, a parallel circuit formed by one resistor R and one diode D, and one capacitor C And at least one snubber circuit TX, which are connected in series, are arranged at short mutual intervals, and the conductor frame F
Including the midpoint between RP _and FR _N , the conductor frame FR _{P and} FR _N
The self-extinguishing element module T with respect to a plane perpendicular to
M and the snubber circuit TX are arranged symmetrically, the forward direction of the diode D is arranged from the positive potential conductor frame FR _P to the negative potential conductor frame FR _N, and the feeding point of the DC power source CVT is arranged. An inverse converter, characterized in that power receiving points M _P, M _N corresponding to S _P, S _N are provided near the intermediate points of the conductor frames FR _P, FR _{N ,} respectively. 2. The inverse conversion device according to claim 1, wherein the snubber circuit TX corresponding to the self-extinguishing element module TM is an element molded and molded integrally.