JPH0744825B2 - Snubber regenerative device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a snubber regenerating device for regenerating energy of a snubber circuit associated with a switching operation of a self-extinguishing element which constitutes an inverter or a chopper device.

[0002]

2. Description of the Related Art FIG. 14 is a block diagram of a chopper device having a conventional snubber circuit. In the figure, Vd is a DC power source,
GTO is a self-extinguishing element, DF is a wheeling diode.
DO, LA is an anode reactor, LOAD is a load, Ds
, Cs, and Rs are a diode, a capacitor, and a discharge resistor that form a snubber circuit, respectively. FIG. 15 shows FIG.
The operation waveforms of the respective parts of the chopper device are shown.

When the self-extinguishing element (hereinafter simply referred to as GTO) is turned on, a voltage of VL = + Vd is applied to the load LOAD, and the load current IL increases. When the GTO turns off, VL becomes 0 and the current I flowing through the load LOAD
L flows through the wheeling diode DF and decays.

The anodic reactor LA functions to prevent the short-circuit current from increasing from the DC power supply Vd until the wheeling diode DF is turned off when the GTO is turned on. Normally, the value of LA is designed in consideration of (di / dt) of GTO. The snubber circuit plays a role in absorbing the surge voltage generated by the anodic reactor LA and the inductance of the wiring when the GTO is turned off.

That is, in the absence of the snubber circuit, when the GTO is turned off, the load current IL circulates through the wheeling diode DF as described above, but the anodic reactor L
The current flowing in A has no place to go, and an excessive voltage is applied to the GTO, destroying the GTO. When the snubber circuit is connected, when the GTO is turned off, the energy of the anodic reactor LA is stored in the capacitor Cs via the diode Ds and charges the capacitor Cs to the polarity shown in the figure. The voltage charged in the capacitor Cs is discharged through the discharge resistor Rs when the GTO is next turned on, and prepares for the next turn-off. The capacitor C is shown at the bottom of FIG.
The voltage Vc applied to s is shown.

In this conventional snubber circuit, the capacitor C
All the energy stored in s is consumed by the discharge resistance Rs, resulting in heat loss. This heat loss is proportional to the switching frequency of the GTO,
There is a drawback that not only lowers the conversion efficiency of the device but also increases the device size. At the same time, the cooling method becomes difficult as the capacity increases. In order to solve this, a snubber energy regeneration method is being studied. FIG. 16 shows the configuration of a conventional snubber regenerative device.

In the figure, Eo is an auxiliary DC power source, Do is a regeneration diode, and other symbols are the same as in FIG. Instead of the discharge resistance Rs, a regeneration diode Do and an auxiliary power source Eo are provided.

When the GTO is turned off, the energy of the anodic reactor LA is stored in the capacitor Cs. As a result, the capacitor Cs is charged to the polarity shown. next,
When the GTO is turned on, the voltage of the capacitor Cs is regenerative diode Do → auxiliary power supply Eo → anode reactor LA
→ GTO → Discharge in the circuit of capacitor Cs. The current flowing at this time is the resonance current IR due to the capacitor Cs and the anodic reactor LA. The discharge is completed when the voltage Vc of the capacitor Cs becomes zero. After that, the current IR
Is the anode reactor LA → diode Ds → regeneration diode Do → auxiliary power supply Eo → anode reactor LA
, And energy is regenerated to the auxiliary power supply.

The auxiliary power source Eo is a direct current power source having a regenerative ability. For example, once the energy is stored in a direct current capacitor,
This DC power is converted into AC power by the PWM control inverter. Then, a method of regenerating this AC power to an AC power source via a transformer, a method of converting the AC power into a direct current by a rectifier and regenerating it to the main DC power source Vd, and the like can be considered. In either case, the DC voltage is controlled by the PWM control inverter so that Eo becomes constant. Auxiliary power supply voltage Eo
Is usually selected to be a value lower by one digit than the main DC power supply voltage Vd. This is because if the voltage Eo of the auxiliary power source is too high, the withstand voltage of the PWM control inverter becomes high, resulting in an uneconomical system.

[0010]

However, this conventional snubber regenerative device has the following problems.

In the circuit of FIG. 16, when the GTO is turned off, the voltage VC charged in the capacitor Cs is the current IL flowing in the anodic reactor LA as the DC voltage Vd.
The voltage of the energy component is added. That is, (1/2) ・ LA ・ IL ² = (1/2) ・ Cs ・ (Vc ² -Vd ² ) Is applied to the capacitor Cs. LA = 20 μH, Cs = 6 μF, Vd = 1,000 V,
If IL = 500A, Vc = 1,354V.

When the GTO is turned on, a voltage of Vc-Eo is applied to the anode LA, and a resonance current IR due to the capacitor Cs and the anode LA shown by the following equation flows. IR = (Cs / LA). (Vc-Eo) .sin .omega.Rt where .omega.R is the resonance angular frequency. When Eo = 100V and the above constants are substituted, the maximum value of IR is 687A.
become. In addition to this resonance current, the GTO has a load current I.
L also flows. That is, the maximum value of the current flowing in the GTO is 1,
It will be 187A.

In order to suppress the maximum value of the resonance current IR, it may be considered to insert a reactor Lo in series with the regenerative diode Do as shown in FIG. In that case, the maximum value IRm of the resonance current is IRm = (Cs / (LA + Lo)). (Vc-Eo). For example, to reduce IRm to 100A, L
It suffices to insert a reactor of o = 923 μH. However, due to the insertion of the reactor Lo, the capacitor C
The discharge time of s becomes longer. Discharge time ΔTs is the number of resonance weeks f
It is represented by the following equation in the R quarter cycle. ΔTs = (1/4) ・ 2π ・ (Cs ・ (LA + Lo)) = 118 μsec

After this, further reactor (LA + Lo)
The time ΔTo is required to regenerate the stored energy in the auxiliary power source. That is, when the voltage Eo is constant at 100V,
The time until IRm = 100A becomes zero is ΔTo = (IRm / Eo)  (LA + Lo) = 943 μsec. In total, ΔTs + ΔTo = 1,061 μsec, which is one time longer than that of a normal snubber circuit (without regeneration), which is unusable.

As described above, in the conventional snubber regenerative device, an excessive current is passed through the GTO when the voltage of the snubber capacitor Cs is discharged, and the current capacity of the element must be increased accordingly. GT that constitutes the main circuit
Increasing the current capacity of O not only increases the cost of the device, but also increases the loss of elements and increases the geometrical dimensions. This is a large-capacity inverter, etc., and is remarkable in a device that uses a large amount of GTO. Also, if a reactor or the like is inserted in order to suppress the increase in current, the discharge time of the snubber capacitor will be delayed, making it unusable for a GTO with a high switching frequency.

The present invention has been made in view of the above problems, and in a snubber regeneration device of a GTO which constitutes a large capacity chopper device or an inverter device, the snubber capacitor is quickly discharged and the GTO is also discharged. It is an object of the present invention to provide a snubber regenerative device that suppresses an increase in current during turn-on.

[0017]

In order to achieve the above object, a snubber regenerative device of the present invention comprises an anodic reactor (LA) and a self-extinguishing arc connected in series to the anodic reactor (LA). Element (GTO) and the self-extinguishing element (GTO)
), A series circuit of a snubber diode (Ds) and a snubber capacitor (Cs) connected in parallel, and the snubber diode (Ds) and the snubber capacitor (Cs) for discharging the voltage of the snubber capacitor (Cs). A regeneration diode (Do) with one terminal connected to the connection point with
It is characterized by comprising a direct current source (SUP) connected between the other terminal of the regeneration diode (Do) and the anodic reactor (LA).

[0018]

The DC constant current source SUP is, for example, an AC power supply AC-SUP, an AC / DC power converter SS, a DC reactor Lo, and the AC / AC so that the current flowing through the DC reactor Lo becomes constant. It is composed of a control circuit for controlling the DC power converter SS.

This DC constant current source SUP is irrespective of the charging / discharging of the snubber capacitor Cs, the DC constant current source SUP → Anode reactor LA → Snubber diode Ds → Regeneration diode Do → DC constant current source SUP. A constant direct current is flowing through the path. Specifically, an AC / DC power converter SS and a DC reactor Lo are provided, and the DC reactor L
The AC / DC power converter SS is controlled so that the current flowing in o becomes constant.

This DC current value Io is selected to be a value smaller than IL by about one digit than the rated current of the main circuit. Also, the inductance value of the DC reactor Lo is selected to be a large value of about 10 mH to suppress current ripple.

When the GTO is turned on, a current that is the sum of the load current IL and the constant current Io flows through the GTO. Since the DC constant current Io is smaller than the load current IL by one digit, an increase in the element current does not pose a problem.

When the GTO is turned off, the load current component IL flowing in the anodic reactor LA is cut off, and the snubber capacitor Cs is charged via the snubber diode Ds. Next, when the GTO is turned on, a reverse bias voltage is applied to the snubber diode Ds and the current I of the DC constant current source SUP is increased.
o is a DC constant current source SUP → anonode reactor LA → G
TO → snubber capacitor Cs → regeneration diode Do →
It flows in the path of the DC constant current source SUP. This current path continues until the voltage VC of the snubber capacitor Cs becomes zero. Time Δ until the voltage Vc of the snubber capacitor Cs becomes zero
To becomes as follows when the current Io is a constant value. When ΔTo = Vc.multidot.Cs / Io Vc = 1,000V, Cs = 6 .mu.F and Io = 100A, .DELTA.To = 60 .mu.sec.

When the capacitor voltage Vc = 0, the snubber diode Ds becomes conductive again, and the current Io of the DC constant current source SUP is the DC constant current source SUP → anode reactor LA → snubber diode Ds → regeneration. For dio
Do Do → Flows through the path of the DC constant current source SUP. After this, the GTO can be turned off at any time. For the GTO, it is sufficient to secure the minimum on-time of ΔTo = 60 μsec.

The DC constant current source SUP is composed of, for example, an AC power supply AC-SUP, an AC / DC power converter SS, and a DC reactor Lo, and a snubber capacitor C.
Energy of s (1/2) Cs.Vc ² Is once transferred to the DC reactor Lo, further converted into AC power by a power converter (eg, thyristor converter) SS, and regenerated by the AC power supply AC-SUP. In this way, the energy stored in the snubber capacitor Cs can be regenerated in the DC constant current source SUP. In the snubber regenerator of the present invention, the GTO current is slightly increased, and the snubber capacitor Cs discharge time can be shortened.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a snubber regenerating device of the present invention and is a configuration diagram applied to a chopper device.

In the figure, Vd is a direct current power source, LA is an anode reactor, GTO is a self-extinguishing element, LOAD is a load, and D is a load.
F is a freewheeling diode, Cs is a snubber capacitor, Ds is a snubber diode, and Do is a regeneration diode.
, SUP is a DC constant current source, CTL is a load current detector,
CONT L is a load current control circuit.

The DC constant current source SUP is an AC power supply AC-S.
It comprises an UP, a transformer TR, a separately excited thyristor converter (AC / DC power converter) SS, a DC reactor Lo, a current detector CTo and a control circuit CONTo.
First, the control operation of the load current IL will be briefly described. The load current control circuit CONTL is composed of a comparator CL, a current control compensation circuit GL (s), a pulse width modulation control circuit PWMC, and a triangular wave generator TRG.

The load current IL is detected by the current detector CTL, and the current command value IL ^* is detected by the comparator CL ^. The deviation .epsilon.L is amplified by the current control compensation circuit G (s) and input to the pulse width modulation (PWM) control circuit PWMC.

FIG. 2 is a time chart for explaining the PWM control operation. In the figure, X is a carrier wave (triangular wave) signal of PWM control, ei is an input signal (voltage reference signal) given from the current control compensation circuit GL (s), and g1 is GTO.
Gate signal, VL is the voltage applied to the load LOAD,
IL represents the load current, respectively. 0 to + E as carrier wave X
A triangular wave varying between max is used and compared with the input signal ei to produce the GTO gate signal g1. That is, when ei> X, g1 = 1 and GTO: ON. When ei ≤X, g1 = 0 and GTO: OFF. The voltage VL applied to the load LOAD is VL = + Vd when the GTO is on, VL = 0 when the GTO is off, and the average value of VL is proportional to the input signal ei.

The load current IL increases when the GTO is turned on, and flows in the route of Vd → LA → GTO → LOAD → Vd. Also, when the GTO is turned off, the load current IL is free.
Flow through Wheeling diode DF and decrease.

IL ^* > IL, the deviation εL becomes a positive value, the PWM control input signal ei increases, and GT
The ON period of O increases. As a result, the output voltage VL increases, the load current IL increases, and IL ^* It is controlled so that = IL.

Similarly, IL ^* When <IL, the deviation εL becomes a negative value, the PWM control input signal ei decreases, and the ON period of the GTO decreases. As a result, the output voltage VL
Decreases, the load current IL decreases, and IL ^* It is controlled so that = IL.

When the GTO is turned off, a surge voltage is generated by the inductance of the wiring and the anodic reactor LA, but the surge voltage is absorbed by the snubber capacitor Cs. Next, the operation of the snubber regenerative circuit will be described.

FIG. 3 shows a more specific partial configuration diagram of the DC constant current source SUP of FIG. In the figure, LA is an anodic reactor, GTO is a self-extinguishing element, Cs is a snubber capacitor, Ds is a snubber diode, and Do is a regeneration diode.
, SUP is a DC constant current source, AC-SUP is a 3-phase AC power supply, TR is a 3-phase transformer, and SS is a thyristor S1 to S6.
3-phase separately excited converter, Lo is a DC reactor, CTo is a current detector, CONTo is a control circuit, VR
o is a current command generator, Co is a comparator, G (s) is a current control compensation circuit, and PHC is a phase control circuit. The control circuit CONTo is a current Io flowing in the DC reactor Lo.
The three-phase separately-excited converter SS is controlled so that is constant.

That is, first, the current Io flowing in the DC reactor Lo is detected by the current detector CTo, and the comparator Co is detected.
To enter. With the comparator Co, the current command generator VRo
Current command value from Io ^* And the current detection value Io are compared, and the deviation εo = Io ^* -Io is obtained, this deviation εo is amplified by the control compensation circuit Go (s), and e = εo · Go (s) is input to the phase control circuit PHC of the three-phase separately excited converter SS.

The three-phase separately excited converter SS regulates the DC output voltage Vo by controlling the firing phase angle α of the six thyristors S1 to S6 with respect to the three-phase power supply voltage. When the primary / secondary winding ratio of the transformer TR is 1: 1 and the effective value of the three-phase AC power supply AC-SUP line voltage is VAC, the DC voltage Vo is as follows. Vo = 1.35 ・ VAC ・ COS α

The phase control circuit PHC is based on ordinary cosine wave comparison, and COS α has a value proportional to the input signal e. Therefore, the DC output voltage Vo has a value proportional to the input voltage e. When e has a negative value, the phase angle α becomes larger than 90 °, and the DC voltage Vo also has a negative value.

Io^* > Io, the deviation εo is positive
And the input e of the phase control circuit PHC is increased.
It As a result, the DC voltage Vo increases in the direction of the arrow in FIG.
Then, the direct current Io is increased. Conversely, Io^* <Become Io
Deviation becomes negative, the phase control circuit PH
The input e of C is decreased. As a result, the DC voltage Vo is
Increase in the direction opposite to the direction of arrow 3 and decrease the DC current Io
Russ. Finally Io^* = Io is controlled.

As described above, the DC constant current source SUP is SS → LA → D regardless of charging / discharging of the snubber capacitor Cs.
A constant direct current Io is flowing through the route of s → Do → Lo → SS. This DC current value Io is selected to be a value smaller than IL by about one digit than the rated output current of the main circuit. In order to reduce the ripple of DC current Io, the DC reactor L
The impedance value of o is selected to be about 10 m H.

When the GTO is turned on, a current that is the sum of the load current IL and the direct current Io described above flows through the GTO. Since the DC constant current Io is smaller than the load current IL by one digit, an increase in the element current does not pose a problem.

When the GTO is turned off, the load current IL flowing in the anodic reactor LA is cut off, and the snubber capacitor Cs is charged to the polarity shown in the figure via the snubber diode Ds.

Next, when the GTO is turned on, a reverse bias voltage is applied to the snubber diode Ds, and the DC constant current source SU.
The current Io of P is SS → LA → GTO → Cs → Do → L
o → It flows on the route of SS. This current path continues until the voltage Vc of the snubber capacitor Cs becomes zero. The time ΔTo until the voltage Vc of the snubber capacitor Cs becomes zero is given by the following equation when the current Io is a constant value. .DELTA.To = Vc.multidot.Cs / Io By the way, Vc = 1,354V, Cs = 6 .mu.F, Io =
At 100 A, ΔTo = 81 μsec.

When the capacitor voltage Vc = 0, the snubber diode Ds becomes conductive again, and the current Io of the DC constant current source SUP is SS → LA → Ds → Do → Lo →
It comes to flow on the SS route. After this anytime GT
The O is turned off. As the GTO, it is sufficient to secure the minimum on-time of ΔTo = 81 μsec.

FIG. 4 shows an equivalent circuit diagram for explaining the operation of the snubber regenerative circuit of the apparatus of FIG. In addition, in FIG.
3 shows voltage and current waveforms of each part. The three-phase separately-excited converter SS is represented by a regenerable voltage source that generates a voltage Vo in both the forward and reverse directions, and together with the DC reactor Lo, a DC constant current source SU.
Configure P.

In the circuit of FIG. 4, the maximum value V of the voltage charged in the snubber capacitor Cs when the GTO is turned off.
In cm, the voltage corresponding to the energy due to the current IL flowing in the anodic reactor LA is added to the DC voltage Vd. That is, (1/2) ・ LA ・ IL ² = (1/2) ・ Cs ・ (Vcm ^2- Vd ² ) Is applied to the capacitor Cs. LA = 20 μH, Cs = 6 μF, Vd = 1,000 V,
If IL = 500A, Vcm = 1,354V.
Next, when the GTO is turned on, the voltage Vcm of the snubber capacitor Cs is applied to both ends of the diode Ds, and the applied voltage VDS of Ds is attenuated along with the discharge.

If the direct current Io is constant, the average value of the voltage VDS and the inverted value of the output voltage of the three-phase separately excited converter SS-
Vo becomes equal. That is, when the discharge time is ΔTo and the switching period of the GTO is T, the voltage Vo satisfies T · Vo = − (1/2) · ΔTo · Vcm. ΔTo = Vcm · Cs
Substituting / Io, Vo =-(1/2) .Cs.Vcm It is represented by ² / (T · Io). Under the above conditions, the switching frequency is set to 100
When 0Hz and Io = 100A, Vo = -55V. In this case, if it is ignored that the circuit loss is sufficiently small, about 5.5 KW of electric power will be regenerated to the AC power supply AC-SUP. The ripple Δio of the DC current Io is determined by the value of the DC reactor Lo and the voltage V of the snubber capacitor Cs.
c and the value of the voltage Vo of the 3-phase separately-excited converter SS,
It is approximated as follows. However, ΔTo = T. .DELTA.io = (Vcm-Vo) .multidot..DELTA.To / (2Lo) Lo = 10 m H, .DELTA.To = 81 .mu.sec, Vcm-Vo =
When the voltage is 1,304 V, the current ripple is Δio = 5.3.
It becomes A.

From a micro perspective, the snubber capacitor C
The energy stored in s and
It is moved to o, is further converted into AC power by the three-phase separately excited converter SS, and is regenerated to the AC power supply AC-SUP. In this way, the energy stored in the snubber capacitor Cs can be regenerated in the DC constant current source SUP.

6 to 8 in which the same parts as those in FIG. 3 are designated by the same reference numerals are configuration diagrams showing different embodiments of the DC constant current source SUP used in the snubber regenerative device of the present invention. .

FIG. 6 shows an example in which a current source self-exciting converter is used in place of the separately excited converter shown in FIG.
Is a filter capacitor and SSo is a self-exciting converter. The self-exciting converter SSo is a self-extinguishing element (for example,
(Transistor, GTO, etc.) S1 to S6, and by performing pulse width modulation control (PWM control), the alternating currents IR, IS, I are controlled so that the direct current Io becomes almost constant.
Control T The filter capacitor CAPo is provided to remove the harmonic components of the alternating currents IR, IS and IT. Compared to the separately excited converter method, the AC current is controlled to a sine wave, and the harmonic components are small,
The characteristic is that the power factor improves.

FIG. 7 shows an example using a high frequency link converter. In the figure, DC-SUP is a DC power supply CC, a circulating current type double converter, CAP is a high frequency capacitor, TRH is a high frequency transformer, and SSH is a separately excited converter.
This method is effective when regenerating the snubber energy to the DC power supply DC-SUP.

The circulating current type double converter CC is composed of a positive group converter SSP, a negative group converter SSN, and DC reactors L1 and L2.
The value of the DC power supply current IDC is controlled so that the voltage peak value VCAP of AP becomes almost constant. By controlling the circulating current Icc of the circulating current type double converter CC, the delayed reactive power Qcc on the high frequency power source side can be adjusted.
Circulating current type double converter that takes this delayed reactive power Qcc
The inductor CC can be considered as a kind of inductance, and a high frequency power supply can be established by the resonance phenomenon due to this inductance and the high frequency capacitor CAP. The circulating current type double converter CC and the separately excited converter SSH are naturally commutated by using this high frequency power supply voltage.

When the high frequency power supply is established, the separately excited converter SSH is prepared as in the case described with reference to FIG. 1, so that the DC constant current source SUP is combined with the DC reactor Lo.
Can be configured.

In this case, the energy of the snubber capacitor Cs is transferred to the high frequency capacitor CAP by the DC reactor Lo and the separately excited converter SSH, and further the DC power supply DC-SUP is supplied by the circulating current type double converter CC.
Regenerated to. At this time, the DC power supply DC-SUP may be replaced with the DC power supply Vd of the main circuit of FIG.

This system is characterized by a DC power supply DC-SUP.
Can be regenerated, the circulating current type double converter CC and the separately excited converter SSH can be naturally commutated, and the insulation transformer TRH is a high-frequency transformer, which can reduce the size and weight. .

FIG. 8 shows an example using a double chopper and a DC / DC converter. In the figure, DC-SUP is a DC power supply, D / D-CON is a DC / DC converter, CDC is a DC smoothing capacitor, and CHO is a double chopper circuit. DC / DC converter D / D-CON is a rectifier R
EC, high frequency transformer TRH voltage type PWM inverter I
Composed of NV.

The double chopper circuit CHO is composed of the self-extinguishing elements S1 and S2 and the wheeling diodes D1 and D2, and controls the self-extinguishing elements S1 and S2 so that the direct current Io becomes almost constant. To do.

When the self-extinguishing elements S1 and S2 are turned on, the direct current Io is Lo → S1 → CDC → S2 → LA → Ds →
Do → Lo route (or Lo → S1 → CDC → S2 → L
A → GTO → Cs → Do → Lo)), the voltage of the DC smoothing capacitor CDC decreases, and Io increases.

Further, when both the self-extinguishing elements S1 and S2 are turned off, the direct current Io becomes Lo → D1 → CDC → D2 → LA.
→ DS → Do → Lo route (or Lo → D1 → CDC →
D2 → LA → GTO → Cs → Do → Lo), and the voltage of the DC smoothing capacitor CDC increases and Io decreases. When either one of the self-extinguishing element S1 or S2 is on, the direct current Io is in the return mode without passing through the direct current smoothing capacitor CDC.

The voltage type PWM inverter INV converts the DC voltage of the DC smoothing capacitor CDC into a high frequency AC voltage. High-frequency transformer TRH boosts insulation, rectifier REC
It is rectified by and regenerated to DC power supply DC-SUP.

That is, the energy of the snubber capacitor Cs is temporarily stored in the DC smoothing capacitor CDC via the DC reactor Lo and the double chopper circuit CHO, and then is stored in the DC smoothing capacitor CDC.
/ DC converter D / D-CON regenerates to another DC power supply DC-SUP insulated by. At this time, the DC power supply DC-SUP may be replaced with the DC power supply Vd of the main circuit of FIG. The features of this system are that it can be regenerated to a DC power source and that the size and weight of the insulating transformer can be reduced because of its high frequency.

FIG. 9 showing the same parts as in FIG.
FIG. 6 is a configuration diagram showing another embodiment of the snubber regenerative device of the present invention. The main circuit is a chopper device, but an application example in which two self-extinguishing elements are connected in series is shown. In the figure, GTO
1, GTO2 is a self-extinguishing element, DF is a freewheeling diode, Cs1, Cs2 are snubber capacitors, Ds1, D
s2 is a snubber diode, and Do1 and Do2 are regenerative diodes. The self-turn-off devices GTO1 and GTO2 are turned on and off at the same time to control the current IL flowing through the load LOAD.

When GTO1 and GTO2 are turned off,
The energy of the load current flowing through the reactor LA is transferred to the snubber capacitors Cs1 and Cs2 via the snubber diodes Ds1 and Ds2. At this time, the direct current Io is L
The flow is o → SS → LA → Ds1 → Do1 → Lo.

Next, when GTO1 and GTO2 are turned on,
Reverse bias voltage is applied to the snubber diodes Ds1 and Ds2, and the direct current Io is Lo → SS → LA → GTO1 → C
It flows through the path of s1 → Do1 → Lo, and discharges the voltage Vc1 of the upper snubber capacitor Cs1. Then, the voltage Vc2 of the lower snubber capacitor Cs2 becomes higher than Vc1 and the direct current I
o is Lo → SS → LA → GTO 1 → GTO 2 → Cs 2 →
The voltage Vc2 of the lower snubber capacitor Cs2 is discharged by flowing through the path of Do2 → Do1 → Lo, and as a result, two snubber capacitors are connected in parallel and discharged by the direct current Io. Therefore, in this case, it is necessary to pass a direct current about twice as much as that of the device of FIG. In the above description, the number of self-extinguishing elements in series is two, but three or more self-extinguishing elements can be similarly implemented.

FIG. 1 showing the same parts as in FIG. 9 with the same reference numerals.
Reference numeral 0 is a configuration diagram showing still another embodiment of the snubber regenerative device of the present invention, in which the snubber regenerative device of the present invention is applied to a voltage source inverter for converting DC to AC power of variable voltage variable frequency. The structure of one phase (U phase) is shown.

In the figure, Vd1 and Vd2 are main DC power supplies and L
A1, LA2 anode reactor, DF1, DF2 are freewheeling diodes, TR1, TR2 are transformers, SS1
, SS2 are separately excited converters, Lo1 and Lo2 are DC reactors, CTo1 and CTo2 are current detectors, and CONT1 and CO.
NT2 is a direct current control circuit. FIG. 11 shows voltage-current waveforms of respective parts when the inverter of FIG. 10 is subjected to pulse width modulation control (PWM control). In the PWM control, the carrier wave (triangular wave) X is compared with the output voltage reference ei to generate the gate signal g1 of the self-turn-off devices GTO1 and GTO2. When ei> X, g1 = 1 and GTO1: ON (GTO
2: off) When ei ≤ X, g1 = 0, GTO1: off (GTO
2: ON). When the DC voltage is Vd1 = Vd2 = Vd / 2,
The voltage Vu applied to the U-phase load LOADu becomes Vu = + Vd / 2 when GTO1 is on (GTO2 is off) and Vu = -Vd / 2 when GTO1 is off (GTO2 is on). The average value of the output voltage Vu (shown by the broken line) is proportional to the output voltage reference ei. Therefore, if a sinusoidal voltage is applied as the output voltage reference ei, the voltage V applied to the U-phase load
u becomes a sine wave. Normally, the above voltage reference ei is provided so as to control the current Iu of the U-phase load into a sine wave.
The V-phase and the W-phase are also configured in the same manner, and as a whole, the three-phase load can be supplied with the AC power of the variable voltage and variable frequency.

In such an inverter circuit, a snubber regenerative circuit connected to the positive side electric line (+) of the DC power source Vd is prepared for the upper self-extinguishing element GTO1 and the lower self-extinguishing element is provided. The GTO2 is provided with a snubber regenerative circuit connected to the negative side electric line (-) of the DC power source Vd.

The upper snubber regenerative circuit operates similarly to that shown in FIG. At this time, the AC power supply AC-SUP, the transformer TR1, the separately excited converter SS1, the DC reactor Lo1 current detector CTo1 and the current control circuit CONT1 constitute the first DC constant current source SUP1, and the DC current Io is substantially constant. Are controlled to become. The snubber regenerative circuits of the V-phase and W-phase upper self-extinguishing elements can share the DC constant current source SUP1 through the respective regenerative diodes.

The lower snubber regeneration circuit is a snubber capacitor C
Since the applied voltage of s2 has the polarity shown in the figure, the directions of the regeneration diode Do2 and the separately excited converter Ss2 are in the same direction as shown. Others operate similarly to the upper snubber regenerative circuit. The snubber regenerative circuit of the V-phase and W-phase lower self-extinguishing elements can share the second DC constant current source SUP2 through the respective regenerative diodes. Although FIG. 10 has been described using the three-phase four-wire system, it goes without saying that the same can be applied to the three-phase three-wire system. Further, it can be similarly applied to the snubber regenerative circuit of the upper arm and the lower arm of the neutral point clamp type inverter which generates the output voltage of three levels. In addition, the PWM inverter
However, it goes without saying that the same can be applied to the PWM converter.

FIG. 12 is a block diagram showing another embodiment of the snubber regenerative device of the present invention. This embodiment is applied to a multiple PWM control inverter and shows one output phase. is there.

In the figure, Vd is the main DC power source, INV1
, INV2 are full-bridge connected PWM control inverters, TRO1 and TRO2 are output transformers, LOAD
u is a U-phase load, Do11 to Do14, Do21 to Do24 are regenerative diodes, and SUP1 and SUP2 are DC constant current sources.

The first DC constant current source SUP1 is the DC constant current source SUP shown in FIG. 1 with the suffix 1 added thereto, and the second DC constant current source SUP2 is the DC constant current source shown in FIG. The components of the SUP have the subscript 2 added thereto, and the configurations are the same.

The transformer TRo1 connected to the output terminal of the first inverter INV1 and the transformer TRo2 connected to the output terminal of the second inverter INV2 are respectively connected in series on the secondary side, and are connected to the load LOADu. Voltage Vu = Vu1 +
Supply Vu2. FIG. 13 is a time chart for explaining the PWM control operation of the device of FIG.

X1, X2, Y1, and Y2 are carrier wave signals (triangular waves) for PWM control, and these four signals are shifted by 90 °. The PWM control input signal eu is compared with these triangular waves to generate gate signals for the inverters INV1 and INV2. That is, by comparing the input signal eu with the triangular waves X1 and Y1, the gate signals g11 and g of the self-extinguishing elements GTO11 to GTO14 forming the first inverter INV1.
Make twelve. When eu> X1, g11 = 1 and GTO11: ON (GT
O12: OFF) When eu ≤ X1, g11 = 0, GTO11: OFF (GT
O12: ON) When eu> Y1, g12 = 1, GTO14: ON (GT
O13: Off) When eu ≤ Y1, g12 = 0, GTO14: Off (GT
O13: ON) When the DC voltage is Vd, the first inverter
The output voltage Vu1 of the inverter INV1 is Vu1 = + Vd when GTO11 and GTO14 are on, Vu1 = -Vd when GTO12 and GTO13 are on, and Vu1 = 0 in other modes. The average value of the output voltage Vu2 is also proportional to the input signal eu. Output transformers TR01, T are connected to the load LOADu.
Two inverters INV1 and INV2 via R02
The sum of the output voltages of Vu = Vu1 + Vu2 is applied.

Self-extinguishing elements GTO11 to GTO14, GTO
When each switching frequency of 21 to GTO 24 is 1 KHz, the equivalent carrier frequency of the voltage Vu applied to the load LOADu is 4 kHz.

Self-extinguishing elements GTO11 to GTO14, GT
Snubber capacitors Cs11 to Cs14, C for O21 to GTO24
s21 to Cs24 and snubber diodes Ds11 to Ds14, Ds2
1 to Ds24 and regeneration diodes Do11 to Do14, Do2
Install 1 to Do24 and regenerate diode Do1 for upper arm
1, Do13, Do21, Do23 are the first DC constant current source SU
Connect to P1 to connect the lower arm regeneration diode Do12,
Do14, Do22, and Do24 are the second DC constant current source SUP2
Connect to.

In the multiple PWM inverter, the switching timings of the self-extinguishing elements GTO11 to GTO14 and GTO21 to GTO24 are deviated, so that the upper side voltage Vc1 and the lower side voltage Vc2 generated via the regeneration diode are FIG.
As shown in the bottom row. When the self-extinguishing elements GTO11, GTO13, GTO21, GTO23 are turned on, the upper side voltage Vc1 generates a voltage having a peak value Vcm and is attenuated at a time .DELTA.To. When the on timings of the two elements overlap, the higher voltage is generated in the two snubber capacitors, and when the same voltage is reached, the two snubber capacitors are connected in parallel and discharged. During the discharge time δ in the parallel connection, the voltage attenuation coefficient becomes half.

The switching frequency of the self-extinguishing element is set to 1K.
In the case of HZ, the voltage Vc1 pulse cycle supplied to the upper DC constant current source SUP1 is T = 250 μsec = 1 / 4K
It becomes HZ, and the voltage Vo of the separately excited converter is Cs = 6μ
If F, Vcm = 1,354V and Io = 100A, then Vo =-(1/2) .Cs.Vcm ² / (T · Io) = 220V. The same applies to the lower DC constant current source SUP2. In this case, if the circuit loss is sufficiently small and ignored, a total of about 44 KW of power will be regenerated to the AC power supply AC-SUP. Although FIG. 12 has been described with respect to the multiple operation of the two full-bridge connection inverters, the other multiple PWM control operation can be similarly performed.

[0078]

As described above, according to the snubber regenerator of the present invention, the current flowing through the self-extinguishing element forming the main circuit is not increased, and the snubber capacitor voltage discharge time is sufficiently shortened. This makes it possible to reduce the minimum on-time of the self-extinguishing element. As a result, the control range of the PWM control is expanded, and the control can be performed even at a high switching frequency.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a snubber regeneration device of the present invention.

FIG. 2 is a time chart for explaining the operation of the snubber regenerative device of FIG.

FIG. 3 is a specific configuration diagram of a DC constant current source used in the device of FIG.

FIG. 4 is an equivalent circuit diagram for explaining the operation of the snubber regenerative device of FIG.

FIG. 5 is an operation waveform diagram of [FIG. 4].

FIG. 6 is a configuration diagram of another embodiment of a DC constant current source used in the snubber regenerative device of the present invention.

FIG. 7 is a configuration diagram of another embodiment of the DC constant current source used in the snubber regenerator of the present invention.

FIG. 8 is a configuration diagram of another embodiment of a DC constant current source used in the snubber regenerative device of the present invention.

FIG. 9 is a configuration diagram showing another embodiment of the snubber regenerative device of the present invention.

FIG. 10 is a configuration diagram showing still another embodiment of the snubber regenerative device of the present invention.

FIG. 11 is a time chart for explaining the operation of the snubber regenerative device of FIG.

FIG. 12 is a configuration diagram showing still another embodiment of the snubber regenerative device of the present invention.

FIG. 13 is a time chart for explaining the operation of the snubber regenerative device of FIG.

FIG. 14 is a configuration diagram of a conventional snubber regenerative device.

FIG. 15 is a time chart for explaining the operation of the conventional snubber regenerative device of FIG.

FIG. 16 is a configuration diagram showing another example of a conventional snubber regenerative device.

FIG. 17 is a configuration diagram showing still another example of a conventional snubber regenerative device.

[Explanation of symbols]

 Vd: DC power supply LA: Anode reactor GTO: Self-extinguishing element LOAD: Load DF: Freewheeling diode Cs: Snubber capacitor Ds: Snubber diode Do: Regeneration diode -Dup ...... DC constant current source CTL ...... Load current detector CONTL ...... Load current control circuit AC-SUP ...... AC power supply TR ...... Transformer SS ...... Externally-excited thyristor converter Lo ...... DC reactor CTo …… … Current detector CONTo …… Control circuit SSo …… Self-excited current type power converter CAPo …… Filter capacitor CC …… Double converter TRH …… High frequency transformer CAP …… High frequency capacitor SSH …… Separately excited converter DC -SUP: DC power supply D / D-CON: DC / DC converter CDC: DC smoothing capacitor CH ...... double chopper circuit

Claims (5)

[Claims] 1. A self-extinguishing element that constitutes a chopper circuit
Column connected anode - and de reactor, snubber diode connected in parallel to said self-turn-off device - a series circuit of a de snubber capacitor, said in countercurrent to discharge the voltage of the snubber capacitor snubber - de and a snubber capacitor A regenerative diode with one terminal connected to the connection point of
It is connected to the other terminal of the regenerative diode through the anodic reactor and is controlled so that the current flowing through the regenerative diode becomes almost constant.
A snubber regenerative device having a DC constant current source having a regenerative function . 2. The DC constant current source includes an AC power source and an AC side.
Is connected to the AC power supply, and a DC reactor is installed on the DC side.
An AC / DC power converter provided, snubber according to claim 1, characterized in that current flowing through the DC reactor is composed of a control circuit for controlling the AC / DC power converter to be constant Regenerative device. 3. The DC constant current source, wherein the AC side is an AC power source.
Voltage type P connected and equipped with a DC smoothing capacitor on the DC side
DC voltage source consisting of WM converter and output side to the DC power source
And <br/> double chopper circuit but DC reactor is connected in series connected to the input side, that the current flowing through the DC reactor is composed of a control circuit for controlling said double chopper circuit to be constant The snubber regeneration device according to claim 1, which is characterized in that. 4. A chopper circuit comprising at least two identical circuits.
A series circuit of self-extinguishing elements sometimes given a gate signal
A series circuit of an anodic reactor connected in series to the series circuit, a series circuit of a snubber diode and a snubber capacitor connected in parallel to the respective self-extinguishing elements, and a direction for discharging the voltage of each snubber capacitor. At one terminal is connected to the connection point between the snubber diode and the snubber capacitor, and at least two regenerative diodes each connected in series are connected to the front end via the anodic reactor.
Serial regenerative diode - connected between the other end terminal of de, the regenerating diodes - a DC constant current source for current flowing through the soil with a regeneration function which approximately is controlled to be constant Snubber regeneration device equipped with. 5. Both ends are through anodic reactors.
At least two series-connected between positive and negative buses
A pair of positive and negative self-extinguishing elements, and
And a freewheeling diode connected in reverse parallel
A pair of positive and negative self-extinguishing elements are connected in parallel.
Equipped with series circuit of Nava diode and snubber capacitor
AC from the series connection point of the pair of positive and negative self-extinguishing elements
In the power converter with the terminal derived, the snubber capacitor
The snubber diode and the switch to discharge the voltage of the sensor.
Positive with one terminal connected to the connection point with the capacitor
A pair of negative regeneration diodes and the positive regeneration diode
Connected between the other terminal and the positive bus.
The current flowing through the regenerative diode is almost constant.
Positive side DC constant with regenerative function controlled to
Current source and the other terminal of the negative side regeneration diode
Is connected between the negative side busbar and the negative side regenerative diode.
-Controlled so that the current flowing through the
Snubber regenerative device including a negative side DC constant current source having a regenerative function .