JPH05236734A - Snubber regenerating circuit - Google Patents

Abstract

PURPOSE:To provide a snubber circuit which can regenerate the energy of the snubber circuit of a self extinguishing element which constitutes an inverter or a chopper circuit. CONSTITUTION:This circuit has a self-extinguishing element GTO, a reactor for current suppression connected in series to the self-extinguishing element GTO, a series circuit of a snubber diode Ds connected in parallel with the self-extinguishing element GTO and a snubber capacitor Cs, and a first diode D1 for regeneration whose one terminal is connected to the junction between the snubber diode Ds and the snubber capacitor Cs in the direction of discharging the voltage of that snubber capacitor Cs. A snubber circuit which is equipped with a DC constant current power source CSUP connected between one terminal of the diode D1 for regeneration and a reactor LA for current suppression and a series circuit consisting of a second diode D2 for regeneration connected in parallel with the reactor LA for current suppression and a DC constant power source VSUP.

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. 6 is a block diagram of a chopper device having a conventional snubber circuit. In the figure, Vd is a DC power supply, GT
O is a self-extinguishing element, DF is a wheeling diode,
LA is an anode reactor, LOAD is a load, Ds, C
s and Rs are a snubber diode, a snubber capacitor and a discharge resistor, respectively, which form a snubber circuit. FIG. 7 shows operation waveforms of each part of the chopper device of FIG.

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 serves to absorb the surge voltage generated by the inductance of the anodic reactor LA and the wiring when the GTO is turned off.

That is, in the absence of a 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 snubber capacitor Cs via the snubber diode Ds, and the snubber capacitor Cs.
To the polarity shown. The voltage charged in the snubber capacitor Cs is the discharge resistance R when the GTO is next turned on.
Discharge through s to prepare for the next turn-off. Figure 7
The voltage Vc applied to the snubber capacitor Cs at the bottom of the
Indicates. The voltage Vc of the snubber capacitor Cs is once changed to the DC power supply voltage Vd by the energy of the anodic reactor LA.
It becomes higher, but Cs → R while GTO is off
It discharges along the route of s → LA → Vd → DF → Cs and drops to the power supply voltage Vd.

In this conventional snubber circuit, all the energy stored in the snubber capacitor Cs is consumed by the discharge resistor Rs, resulting in heat loss. This heat loss is G
There is a drawback that not only the conversion efficiency of the chopper device and the inverter device is reduced but the device size is increased in proportion to the switching frequency of the TO. 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. Figure 8
Fig. 1 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 snubber capacitor Cs.
As a result, the snubber capacitor Cs is charged to the polarity shown. Next, when the GTO is turned on, the voltage of the snubber capacitor Cs is discharged in the circuit of regeneration diode Do → auxiliary power source Eo → anode reactor LA → GTO → snubber capacitor Cs. The current flowing at this time is the snubber capacitor Cs
And the resonance current IR due to the anodic reactor LA.
The discharge is completed when the voltage Vc of the capacitor Cs becomes zero. After that, the current IR goes to the anode reactor L.
A → snubber diode Ds → regeneration diode Do → auxiliary power supply Eo → anodic reactor LA, and energy is regenerated to auxiliary power supply Eo.

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 than the main DC power supply voltage Vd by about one digit. 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, and the system becomes uneconomical.

[0010]

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

In the circuit of FIG. 8, when the GTO is turned off, the voltage VC charged in the snubber capacitor Cs is obtained by adding the voltage corresponding to the energy due to the current IL flowing in the anodic reactor LA to the DC voltage Vd. .. Vc = Vd
When it is charged to + Eo, the regeneration diode Do becomes conductive and the energy of the anodic reactor LA is the auxiliary power supply Eo.
Regenerated to. Therefore, the voltage Vc of the snubber capacitor Cs
Is charged to Vd + Eo.

When the GTO is turned on, a voltage of Vc-Eo is applied to the anodic reactor LA, and a resonance current IR due to the snubber capacitor Cs and the anodic reactor LA as shown by the following equation flows. IR = (Cs / LA). (Vc-Eo) .sin .omega.Rt where .omega.R is the resonance angular frequency fraction. For example, Vd =
If 3,000 V, Cs = 6 μF and LA = 20 μH, then Vc -Eo = Vd, so the maximum value of IR is 1,
It becomes 643A. In addition to this resonance current, the load current IL also flows through the GTO. That is, load current IL = 1,500
The maximum value of the current flowing in GTO is 3,143A.
I'll get into it.

In order to suppress the maximum value of the resonance current IR,
As shown in FIG. 9, it is conceivable to insert a DC reactor Lo in series with the regenerative diode Do. in this case,
The maximum value IRm of the resonance current is IRm = (Cs / (LA + Lo)). Multidot. (Vc-Eo). For example, to reduce IRm to 200A, L
Insert a reactor with o = 1.33 m H. However, inserting the reactor Lo increases the discharge time of the snubber capacitor Cs. The discharge time ΔTs is represented by the following equation in the (1/4) cycle of the resonance week number fR. ΔTs = (1/4) ・ 2π ・ (Cs ・ (LA + Lo)) = 141 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 300 V,
The time until IRm = 200A becomes zero is ΔTo = (IRm / Eo)  (LA + Lo) = 900 μsec. In total, ΔTs + ΔTo = 1,041 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, which is remarkable in a device that uses a large amount of GTO. Also, if a reactor or the like is inserted to suppress the increase in current, the discharge time of the snubber capacitor will be delayed and it will be 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 regenerative device of a GTO which constitutes a large capacity chopper device or an inverter device, the snubber capacitor is discharged quickly and the GTO is discharged. An object of the present invention is to provide a snubber regenerative device that suppresses an increase in current when turning on.

[0017]

In order to achieve the above object, the snubber regenerative device of the present invention is a self-extinguishing element (GTO).
And a current suppressing reactor (LA) connected in series to the self-extinguishing element (GTO), a snubber diode (Ds) and a snubber capacitor (Cs) connected in parallel to the self-extinguishing element (GTO). And a snubber diode for discharging the voltage of the snubber capacitor (Cs) in series.
The first regeneration diode (D1) with one terminal connected to the connection point between the switch (Ds) and the snubber capacitor (Cs).
A DC constant current source (CSUP) connected between the other terminal of the regenerative diode (D1) and the current suppressing reactor (LA), and the current suppressing reactor (L).
A second regeneration diode (D2) connected in parallel to A)
And a direct current constant voltage source (VSUP).

[0018]

The current suppressing reactor LA is connected in series to the GTO in order to suppress the current increase rate (di / dt) when the GTO is turned on.

When the GTO is off, the DC constant current source CSUP is a DC constant current source CSUP → current suppressing reactor LA → snubber diode Ds → first regeneration diode D1 → DC constant current source CSUP. Apply a constant current through the path.

When the GTO is turned off, the energy stored in the wiring inductance and the anodic reactance LA for suppressing the current is transferred to the snubber capacitor Cs via the snubber diode Ds.

When the charging voltage Vc of the snubber capacitor Cs rises, the energy of the current suppressing reactor LA is regenerated to the DC constant voltage source VSUP via the second regeneration diode D2. That is, the voltage generated by the current suppressing reactor LA is suppressed to the voltage EDC of the DC constant voltage source VSUP. In the case of the chopper circuit, the maximum value Vcm of the voltage charged in the snubber capacitor Cs is the main DC voltage Vd, the voltage ΔE due to the wiring inductance Ic, and the DC constant voltage source V.
It becomes the sum of the voltage EDC of SUP. Vcm = Vd + .DELTA.E + EDC .DELTA.E = Ic.multidot. (Di / dt) The voltage EDC of the DC constant voltage source VSUP is selected to be one digit smaller than the main DC power supply voltage Vd. Considering that ΔE is sufficiently small, for example, Vd = 3,000V, EDC = 30
If 0V, Vcm = 3,300V.

The DC constant voltage source VSUP is a voltage source capable of regenerating electric power, and is composed of, for example, a DC smoothing capacitor and a DC / DC converter. Therefore, the energy of the reactor LA for suppressing the current is first transferred to the snubber capacitor Cs. After that, most of the power is regenerated to the DC constant voltage source VSUP.

Next, when the GTO is turned on, the current Io of the DC constant current source CSUP is CSUP → LA → GTO → Cs.
→ D1 → CSUP flows. That is, the voltage Vc of the snubber capacitor Cs is discharged with the constant current Io. DC current Io is the rated current (load current) IL of the main circuit
It is chosen to be one digit smaller.

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. The time ΔTo until the voltage Vc of the snubber capacitor Cs becomes zero is as follows when the current Io is a constant value. When ΔTo = Vc.multidot.Cs / Io Vc = 3,000 V, Cs = 6 .mu.F and Io = 200 A, .DELTA.To = 90 .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 CSUP is CSUP → LA → Ds → D1 →
It comes to flow through the CSUP route. 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 = 90 μsec.

The DC constant current source CSUP is composed of, for example, an AC power supply AC-SUP, an AC / DC power converter SS, and a DC reactor Lo, and the energy (1/2) Cs of the snubber capacitor Cs. Vc ² Is once transferred to the DC reactor Lo, further converted into AC power by a power converter (for example, 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 CSUP. In the snubber regenerative device of the present invention, the GTO current increase is small,
Moreover, it is possible to shorten the discharge time of the snubber capacitor Cs.

[0027]

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

In the figure, Vd is a DC power source, Lc is a wiring inductance, LA is a current suppressing anodic reactor, and GT.
O is a self-extinguishing element, LOAD is a load, DF is a freewheeling diode, Cs is a snubber capacitor, Ds is a snubber diode, D1 is a first regeneration diode, CS
UP is a DC constant current source, D2 is a second regeneration diode V.
SUP is a DC constant voltage source, CTL is a load current detector, CO
NTL is a load current control circuit. First, the load current IL
The control operation of will be briefly described. Load current control circuit CON
TL is composed of a comparator CL, a current control compensation circuit GL (s), a pulse width modulation control circuit PWML, 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 ^. Deviation from ε L = IL ^* -Calculate IL. The deviation ε L is amplified by the current control compensation circuit G (s) and input to the pulse width modulation (PWM) control circuit PWML. FIG. 2 is a time chart for explaining the PWM control operation. In the figure, X is a PWM controlled carrier wave (triangular wave) signal, ei is an input signal (voltage reference signal) given from the current control compensation circuit GL (s), g1 is a GTO gate signal, and VL is a load LOAD.
The voltage IL applied to the load current I L represents the load current. As the carrier wave X, a triangular wave varying between 0 and + Emax is used and compared with the input signal ei to generate 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 and 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 through 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 ^* = IL is controlled.

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 ^* = IL is controlled.

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.
The DC constant current source CSUP, when the GTO is off,
It is controlled so that a constant current flows through the path of CSUP → LA → Ds → D1 → CSUP.

When the GTO is turned off, the energy stored in the wiring inductance and the current limiting anodic reactor LA is transferred to the snubber capacitor Cs via the snubber diode Ds.

When the charging voltage Vc of the snubber capacitor Cs becomes high, the energy of the current suppressing reactor LA becomes the second level.
DC constant voltage source VSUP via regenerative diode D2
Regenerated to. That is, the voltage generated by the current suppressing reactor LA is suppressed to the voltage EDC of the DC constant voltage source VSUP.

In the chopper circuit of FIG. 1, the maximum value Vcm of the voltage charged in the snubber capacitor Cs is the sum of the main DC voltage Vd, the voltage ΔE due to the wiring inductance Lc and the voltage EDC of the DC constant voltage source VSUP. .. Vcm = Vd + ΔE + EDC ΔE = Lc ・ (di / dt)

The voltage EDC of the DC constant voltage source VSUP is selected to be one digit smaller than the main DC power source Vd. Considering that ΔE is sufficiently small, for example, Vd = 3,000V, EDC =
If it is 300V, Vcm = 3,300V.

The DC constant voltage source VSUP is a voltage source capable of regenerating electric power, and is composed of, for example, a DC smoothing capacitor and a DC / DC converter. Therefore, the energy of the current suppressing reactor LA first transfers to the snubber capacitor Cs, but after that, most of it is regenerated to the DC constant voltage source VSUP.

Next, when the GTO is turned on, the current Io of the DC constant current source CSUP is CSUP → LA → GTO → Cs.
→ D1 → CSUP flows. That is, the voltage Vc of the snubber capacitor Cs is discharged with the constant current Io. This DC current Io is selected to be one digit smaller than the rated output current (load current) IL of the main circuit.

When the GTO is turned on, a current that is the sum of the load current IL and the direct current Io flows through the GTO. Since the DC constant current Io is smaller than the load current by one digit, the increase in the device current does not pose a problem. Voltage V of snubber capacitor Cs
The time ΔTo until c 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 = 3,000V, Cs = 6 .mu.F, Io =
At 200 A, ΔTo = 90 μsec.

When the capacitor voltage Vc = 0, the snubber diode Ds becomes conductive again, and the current Io of the DC constant current source CSUP is CSUP → LA → Ds → D1 →
It comes to flow through the CSUP route. 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 = 90 μsec.

The DC constant current source CSUP is composed of an AC power supply AC-SUP, an AC / DC power converter SS, and a DC reactor Lo as shown in FIG. 3, for example, and the energy of the snubber capacitor Cs (1 / 2) ・ Cs ・ Vc ²
Is once transferred to the DC reactor Lo, further converted into AC power by a power converter (for example, 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 CSUP. In the snubber regenerator of the present invention, the GTO current is slightly increased, and the snubber capacitor Cs discharge time can be shortened. FIG. 3 is a block diagram showing a more specific embodiment of the apparatus shown in FIG.

In the figure, Vd is the main DC power supply, LA is the anodic reactor for current control, GTO is the self-extinguishing element, LOAD is the load, and DF is the freewheeling diode.
Cs is a snubber capacitor, Ds is a snubber diode
D, D1 is the first regeneration diode, AC-SUP is 3
Phase AC power supply, TR1 and TR2 are transformers, SS is separately excited converter, Lo is DC reactor, D2 is second regeneration diode, CDC is DC smoothing capacitor, CONV is self-excited converter, ACL Is an AC reactor, CONT1
, CONT2 are control circuits.

The first control circuit CNT1 is composed of a current control circuit ACR and a phase control circuit PHC, and controls the separately-excited converter SS so that the current Io flowing through the DC reactor Lo becomes constant.

The second control circuit CONT2 includes a voltage control circuit V-CONT, an input current control circuit I-CONT,
The pulse width modulation control circuit PWMC controls the self-exciting converter CONV so that the voltage EDC of the DC smoothing capacitor CDC becomes constant. First, the first control circuit C0
The operation of NT1 will be described.

DC detector L by current detector CTo
The current Io flowing through o is detected and input to the current control circuit ACR. With the current control circuit ACR, the current command value Io ^*
And the current detection value Io are compared, and the deviation εo = Io ^* -Calculate Io. This deviation ε o is amplified by a control compensation circuit Go (s) (not shown) in the current control circuit ACR, and e = ε o · G
Input o (s) to the phase control circuit PHC of the separately excited converter SS.

The separately-excited converter SS is a thyristor converter with a three-phase bridge connection, and is 6
The DC output voltage Vo is adjusted by controlling the firing phase angle α of each of the thyristors S1 to S6. Transformer TR1
3-phase AC power supply AC with the primary / secondary winding ratio of 1: 1
-When the effective value of the line voltage of SUP is VAC, the DC voltage Vo is given by the following equation. Vc = 1.35 ・ VAC ・ cosα

The phase control circuit PHC uses a normal cosine wave comparison.
Therefore, cos α has a value proportional to the input signal e.
It Therefore, the DC output voltage Vo is a value proportional to the input signal e.
Becomes If e is a negative value, the phase angle α is greater than 90 °.
As a result, the DC voltage Vo becomes a negative value. Io^* ＞ Io
, The deviation εo becomes a positive value and the phase control circuit
Increase the input e of PHC. As a result, the DC voltage Vo
Increases in the direction of the arrow in FIG. 3 and increases the direct current Io. Reverse
Io^* <Io, the deviation εo becomes a negative value.
The input e of the phase control circuit PHC is reduced. This conclusion
As a result, the DC voltage Vo increases in the direction opposite to the arrow in FIG.
Reduce the current Io. Eventually, Io^* = Io
To be controlled.

As described above, the DC constant current source CSUP has a constant DC current I regardless of charging / discharging of the snubber capacitor Cs.
o is flowing. This DC current value Io is selected to be a value smaller by about one digit than the rated current IL of the main circuit. In order to reduce the ripple of DC current, the inductance value of DC reactor Lo is selected to be about 10 mH. G
When TO is turned on, a current that is the sum of load current IL and constant DC current Io flows through GTO. Since the DC constant current Io is smaller than the load current IL by one digit, the increase in the device current does not pose a problem. Next, the operation of the second control circuit CONT2 will be described.

Detecting voltage EDC of DC smoothing capacitor CDC
Input to the voltage control circuit V-CONT. Voltage control circuit
Path V-CONT is DC voltage command value EDC^* And voltage detection value
EDc is compared and its deviation εv = EDC^* -Amplify EDc
, AC current peak value command Im^* make. This peak price finger
Im^* Unit synchronized with the voltage of AC power supply AC-SUP
AC current command value Is multiplied by sine wave sinωt
^* = Im^* Make sinωt. Im^* Is a positive value and the power
Return to the AC power supply AC-SUP, that is, the power is
Select the direction of the current to be generated. AC current control circuit I
-CONT is the current command value Is^* And the current detection value Is
And the deviation ε1 = Is^* PWM control by amplifying -Is
It is given to the control circuit PWMC. Self-exciting converter CONV is P
By WM control, the AC current control circuit I-CONT
A voltage proportional to the output signal e2 is generated, and Is = Is^*
Control so that

EDC ^* When EDC is exceeded, the deviation εv becomes a positive value, and the peak value command Im ^{* of the} alternating current Increase
The energy of the smoothing capacitor CDC is supplied to the AC power supply AC-SUP.
Regenerate.

Also, EDC^* <If EDC, deviation εv
Becomes a negative value, and the AC current peak value command Im^* A negative value
From AC power supply AC-SUP to DC peaceful capacitor
Supply power to CDC. As a result, DC
The voltage EDC of the sensor CDC is kept constant.

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.

Ignoring the inductance of the wiring, the maximum value of the voltage Vc charged in the snubber capacitor Cs is the main DC voltage Vd and the voltage EDC of the DC smoothing capacitor CDC.
Is the sum of When Vc = Vd + EDC, the second
The regenerative diode D2 becomes conductive, and the current of the anodic reactor LA flows in the direction of the DC smoothing capacitor CDC.
As a result, the DC voltage EDC increases and EDC ^* > EDC, and the power is regenerated to the AC power supply AC-SUP as described above.

By transferring a part of the energy of the anodic reactor LA to the snubber capacitor CS, the current of the anodic reactor LA becomes as shown in the following equation: IR1 to IR2
Decays to.

(1/2) LA (IR1 ^2- IR2 ² ) = (1/2) CS (Vcm ^2- Vd ² ) For example, IR1 = 1,500A, Vcm = 3,300V, V
When d = 3,000 V, LA = 20 μH, and Cs = 6 μF, IR2 = 1,297 A.

This current IR2 is the direct current smoothing capacitor CDC.
Is regenerated and finally attenuates to IR = Io. Io is a constant current supplied from the DC constant current source CSUP. The time ΔTR for the current in the anode reactor LA to decay from IR2 to Io is the voltage EDC of the smoothing capacitor CDC.
Is determined by the following equation. .DELTA.TR = (IR2-I0) .LA / EDC For example, IR2 = 1,297A, Io = 200A, EDC =
In case of 300V, LA = 20 μH, ΔTR = 73
μsec. Current of anode reactor LA is IR
The GTO may be turned on at any time after = Io.

Next, when the GTO is turned on, a reverse bias voltage is applied to the snubber diode Ds, and the constant current source CSU
The current Io of P is SS → LA → GTO → D1 → Lo → S
It flows on the route of S. This current path is a snubber capacitor C
This continues until the voltage Vc of s becomes zero.

When the capacitor voltage Vc = 0, the snubber diode Ds becomes conductive again and the constant current source CS
The current Io of UP is SS → LA → Ds → D1 → Lo → S
It comes to flow in the route of S. After this, the GTO can be turned off at any time.

In this way, the energy stored in the snubber capacitor Cs is regenerated in the DC constant current source CSUP, and most of the energy in the anodic reactor LA is regenerated in the DC constant voltage source VSUP. At this time, the maximum voltage Vcm applied to the snubber capacitor Cs is suppressed to Vd + EDC if the inductance of the wiring is ignored, and GT
The current IGTO when the O is on can be suppressed to the sum of the load current IL and the constant current Io.

As the DC constant current source CSUP, the AC power source A
C-SUP, separately-excited converter SS, and DC reactor Lo
However, a current-type PWM converter may be used instead of the separately excited converter SS. Further, since the power is regenerated to the DC power source, the DC power source, the chopper device, and the DC reactor Lo can also constitute a DC constant current source CSUP to regenerate the energy of the snubber capacitor Cs with a constant current.

As the DC constant voltage source VSUP, the DC smoothing capacitor CDC, the PWM converter CONV and the AC power supply AC-SUP have been described.
Needless to say, DC, DC / DC converter, and DC power supply may be used, and DC smoothing capacitor CDC, step-up chopper, DC power supply, and the like can be similarly used.

FIG. 4 is a block diagram showing still another embodiment of the snubber regenerator of the present invention. The snubber regenerator of the present invention is used as a voltage source inverter for converting DC into AC power of variable voltage and variable frequency. Applied, 1 phase (U phase)
Shows the configuration of.

In the figure, Vd1 and Vd2 are main DC power supplies and L
A1 and LA2 are anodic reactors for current suppression, GTO1,
GTO2 is a self-extinguishing element, DF1, DF2 are freewheeling diodes, Cs1, Cs2 are snubber capacitors, Ds1,
Ds2 is a snubber diode, D11 and D12 are first regeneration diodes, CSUP1 and CSUP2 DC constant current source, D2
1, D22 is the second regeneration diode, VSUP1, VS
UP2 DC constant voltage source, LOADu is a U-phase load. FIG. 5 shows voltage-current waveforms of respective parts when the inverter of FIG. 4 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, and the gate signal g1 of the self-extinguishing elements GTO1 and GTO2 is compared.
make. 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 is Vu = + V when GTO1 is on (GTO2 is off).
d / 2 When GTO1 is off (GTO2 is on), Vu = -V
It becomes d / 2. 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 is
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, it is possible to supply alternating-current power with a variable voltage and variable frequency to the three-phase load.

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 GTO1. 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. That is, when GTO1 is turned off,
Most of the energy of the reactor LA is a DC constant voltage source V
When the GTO1 is regenerated by the SUP1 and the GTO1 is turned on, the energy of the snubber capacitor Cs is regenerated by the constant current source CSUP1. The snubber regenerative circuit of the V-phase and W-phase upper self-extinguishing elements can share the upper DC constant current source CSUP1 via each first regeneration diode, and each second regeneration diode can be shared. The DC constant voltage source VSUP1 on the upper side can be shared via the.

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 first and second regenerative diodes D12 and D22 and the directions of the DC constant current source CSUP2 and the DC constant voltage source VSUP2 are changed to the directions shown in FIG. Become. 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 lower DC constant current source CSUP2 via each first regeneration diode, and each second regeneration diode. -DC constant voltage source VSUP2 on the lower side via
Can share. Although FIG. 4 was explained using the three-phase four-wire system, the three-phase three
It goes without saying that the same can be done with the line type. 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. Furthermore, although the PWM inverter has been described, it goes without saying that the same can be applied to the PWM converter.

[0068]

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. Therefore, the minimum on-time of the self-extinguishing element can be reduced. As a result, the control range of the PWM control is expanded, and the control can be performed even at a high switching frequency. Further, most of the energy of the current suppressing reactor connected in series with the self-extinguishing element is regenerated to the DC constant voltage source, and the maximum value of the charging voltage of the snubber capacitor can be suppressed.
It is possible to lower the withstand voltage of the self-extinguishing element.

[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 configuration diagram specifically showing a part of the apparatus shown in FIG.

FIG. 4 is a configuration diagram showing another embodiment of the snubber regenerative device of the present invention.

FIG. 5 is a time chart for explaining the operation of the snubber regenerative device of FIG.

FIG. 6 is a configuration diagram showing a conventional snubber regenerative device.

FIG. 7 is a time chart for explaining the operation of the conventional snubber regenerative device of FIG. 6;

FIG. 8 is a configuration diagram showing another example of a conventional snubber regenerative device.

FIG. 9 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 D1: First Regeneration diode CSUP ...... DC constant current source D2 …… Second regeneration diode VSUP …… DC constant voltage source CSUP …… DC constant current source CTL …… Load current detector CTo …… Current detector CONT ...... Load current control circuit CONT1 ...... First control circuit CONT2 ...... Second control circuit SS ...... Externally excited converter CONV ...... Self-excited converter AC-SUP ...... AC power supply TR1, TR2 ... … Transformers TR1 and TR2… Transformer Lo …… DC reactor ACL …… AC reactor CDC …… DC smoothing reactor

Claims (2)

[Claims] 1. A self-extinguishing element (GTO), a current suppressing reactor (LA) connected in series with the self-extinguishing element (GTO), and a snubber connected in parallel with the self-extinguishing element (GTO). -Diode (Ds) and snubber capacitor (C
s) and a first circuit in which one terminal is connected to a connection point between the snubber diode (Ds) and the snubber capacitor (Cs) so as to discharge the voltage of the snubber capacitor (Cs). And a DC constant current source (CSUP) connected between the other terminal of the regeneration diode (D1) and the current suppressing reactor (LA). A snubber regenerative device comprising a series circuit of a second regenerative diode (D2) connected in parallel to the current suppressing reactor (LA) and a direct current constant voltage source (VSUP). 2. A voltage type self-excited converter having a positive side arm and a negative side arm, which are respectively composed of a current suppressing reactor and a self-extinguishing element, in a snubber capacitor of the positive side arm. A positive side DC constant current source for discharging the stored energy with a constant current, a positive side DC constant voltage source for regenerating the energy of the current suppressing reactor of the positive side arm at a constant voltage, and the negative side A negative DC constant current source that discharges the energy stored in the snubber capacitor of the arm with a constant current, and a negative DC constant current source that regenerates the energy of the current limiting reactor of the negative arm with a constant voltage. A snubber regenerative device of a voltage type self-exciting converter equipped with a voltage source.