JPH0568945B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a GTO thyristor converter.

2. Description of the Related Art In general, when a converter is configured with reverse blocking thyristor elements and the output of the converter is supplied to a load by controlling the firing of each element, the power supply voltage and the voltage supplied to the load are determined by a control delay angle α. A phase difference occurs between the two. If the phase differences are not matched, the power factor will decrease, so it is necessary to extinguish each element by forced commutation at the zero point of the voltage on the power supply side.

Problems to be Solved by the Invention Since the forced commutation circuit is provided for each element, the structure of the converter becomes complicated, and since the commutation circuit is large, there is a problem that the structure of the entire converter also becomes large. Furthermore, when the load is operated reversibly, there is a problem in that the circuit configuration becomes extremely complicated. More importantly, there is a problem in that the surge absorbing device that handles the transient voltage during commutation becomes larger.

This invention enables commutation without providing a forced commutation circuit, effectively absorbs and suppresses surges on the power supply side during commutation, and effectively utilizes this energy for reversible operation. In addition, by simplifying the circuit configuration and downsizing the converter, we provide a highly efficient GTO thyristor converter.

Means and operation for solving the problem This invention is composed of a GTO thyristor,
A load capable of reversible operation is connected to the output terminals of a pair of converter bodies that are PWM controlled and have their DC output sides connected in antiparallel, and the electromagnetic energy on the power supply side is generated by rectifying the transient voltage on the power supply side when the converter bodies commutate. The purpose is to store the energy in the capacitor and regenerate the energy stored in the capacitor to the load at a predetermined time.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, AG is a three-phase AC power supply, and the u, v, and w phases of this power supply AG are GTO thyristors G ₁ ~
Converter body formed from G ₆ and G ₂₁ ~ G ₂₆
Connected to the AC input sides of CV ₁ and CV ₂ , respectively. The GTO thyristors G ₁ to _{G 6} and G ₂₁ to _{G 26} are controlled by outputs from a PWM control circuit (not shown). The DC output sides of the converter bodies CV ₁ and CV ₂ are connected in antiparallel to DC buses B ₁ and B ₂ . One DC bus _B1 is a load L (for example, a DC motor) that can be operated reversibly via a DC reactor _Ld .
connected to one end, and the other DC bus _B2 is the load L
connected to the other end.

_D1 to _D6 and _D21 to _D26 are diodes, and these diodes _D1 to _D6 and _D21 to _D26 form diode bridge circuits _DB1 and _DB2 . The AC input sides of both bridge circuits DB ₁ and DB ₂ are connected to the power input terminals of each arm of the converter bodies CV ₁ and CV ₂ . The DC output sides of both bridge circuits DB ₁ and DB ₂ are connected in antiparallel via electronic switches SW ₁ and SW ₂ to both ends of a capacitor C _d . EC is an energy reaction circuit formed from a circuit described later, and this circuit EC is connected between the capacitor C _d and the DC buses B ₁ and B ₂ . Energy reaction circuit EC is GTO thyristor connected in anti-parallel
A first series circuit body in which anti-parallel circuits consisting of G ₇ , G ₈ and G ₉ , G ₁₀ are connected in series, and a GTO connected in anti-parallel
A second series circuit body in which anti-parallel circuits consisting of thyristors G ₁₁ , G ₁₂ and G ₁₃ , G ₁₄ are connected in series is connected to a capacitor.
It is connected between both ends of C _d , and the sum-winding reactors L _r1 and L _r2 are connected separately to the common connection points CO ₁ and CO ₂ of both series circuit bodies and the DC buses B ₁ and B ₂ , respectively. There is.

Next, to describe the operation of the above embodiment, the converter bodies CV ₁ and CV ₂ shown in FIG.
Controlled according to a control gate drive pattern. Note that the converter bodies CV ₁ and CV ₂ differ only in the DC output polarity, so from now on, the DC bus
A case will be described in which the converter main body CV ₁ operates in which B ₁ is the positive pole and the DC bus B ₂ is the negative pole. first,
When GTO thyristors G ₃ and G ₅ are turned on, the direct current
I _d is supplied to load L. At this time, the output voltage e _d of the converter body CV ₁ is the difference between the w-phase voltage and the v-phase voltage, and the AC side input current i _w is positive and i _v is negative. GTO thyristors G ₃ and G ₅ as shown in this fig.
The state where is on is called single current. In this state, GTO thyristor G ₃ is turned off, and at the same time
By turning on _G1 , _G1 and _G5 are turned on. During this time, a commutation operation is performed. This process, ie, the commutation process from single flow to single flow, will be described with reference to FIG. When the GTO thyristor _G3 is turned off, the w-phase current does not immediately become zero due to the power supply reactance, but a transient voltage e _uw is generated. This voltage e _uw is higher than the terminal voltage e _cd of the capacitor C _d because the switch SW ₁ is closed. For this reason, the diode of the diode bridge circuit DB ₁
D ₃ and D ₄ are biased in order, w phase → diode
D ₃ → Capacitor C _d → Diode D ₄ → GTO thyristor G ₁ → Load L → GTO thyristor G ₅ → Current (shown by the solid line in Figure 3) flows in the v-phase loop. The capacitor C _d is charged with this current, and when charging is completed, the diodes D ₃ and D ₄ are turned off, and commutation is completed at this point. In addition, the transient voltage e _uw
The wave height is suppressed by the voltage e _cd of the capacitor C _d .

FIG. 4 shows a diagram when the above-mentioned commutation is completed and a single flow state is established. In this case of FIG. 4, the output voltage e _d of the converter main body CV ₁ is the difference between the voltage of the u phase and the voltage of the v phase, and the AC input current i _u is positive and i _v is negative. The commutation process of turning off the GTO thyristor _G1 and turning on the GTO thyristor _G2 from the state shown in FIG. 4 to a reflux state using the GTO thyristors _G2 and _G5 will be described with reference to FIG.

When GTO thyristor G ₁ is turned off and G ₂ is turned on at the same time, the current i _u does not immediately become zero due to the power supply reactance, but a transient voltage e _uv is generated, similar to the action shown in FIG. Since this voltage e _uv is higher than the terminal voltage e _cd of the capacitor C _d , the diodes D ₁ and D ₅ of the diode bridge circuit DB ₁ are forward biased. As a result, a current as shown by the solid arrow in FIG. 5 flows in the same manner as described above, and the capacitor C _d is charged. When charging is completed, diode _D1 and
_D5 is turned off, commutation is completed, and the electromagnetic energy on the load side is returned to the reflux state. This state is shown in FIG. In order to commutate the current from the reflux state shown in FIG. 6 to single current, the GTO thyristor G ₂ is abruptly turned off and the GTO thyristor G ₃ is turned on, thereby generating a transient voltage e _vw as shown in FIG. 7. Since this voltage e _vw is higher than the terminal voltage e _cd of the capacitor C _d , the diodes D ₂ and D ₆ are forward biased as before. As a result, a current flows as shown by the solid arrow in Figure 7 in the same way as described above, and the capacitor
C _d is charged. When charging is completed, diodes _D2 and _D6 are turned off and commutation is completed. Hereinafter, the GTO thyristors _G1 to _G6 are PWM controlled according to the gate drive pattern shown in FIG. 8B. In addition, Figure 8A in the figure is an AC input voltage waveform diagram, and the parts other than the white part of the waveform indicate that the GTO thyristor is on, and Figure 8B is the gate drive pattern, and the black part is the GTO thyristor. Indicates the period during which the thyristor is on. Further, FIG. 8C is a waveform diagram of the output voltage e _d of the converter main body CV ₁ , and FIG. 8D is a waveform diagram of the input current on the AC side.

Next, in Figures 3, 5, and 7, the transient voltage generated during the commutation process is charged to the capacitor C _d , but the capacitor C _d is charged every time the commutation occurs. e _CD will continue to rise. Therefore, a circuit called energy reaction circuit E _c consisting of GTO thyristors G ₇ to G ₁₄ and Japanese winding reactors L _r1 and L _r2 is used to convert capacitor C _d
A means was taken to supply the charging load (charging energy) to the load L and process the energy.
That is, in Fig. 9, first from the control circuit (not shown)
Give a signal to turn on GTO thyristors _G7 and _G11 to turn them on. (The ON period of G ₇ and G ₁₁ is after the commutation is completely completed.) By turning on GTO thyristors G ₇ and G ₁₁ , the charging load (charging energy) of capacitor C _d is transferred to GTO thyristor G ₇ .
→Wado winding reactor L _r1 →DC reactor L _d →Load L→Wado winding reactor L _r2 →GTO thyristor
Discharged through G ₁₁ . The current discharged in this way is smoothed by the wave winding reactors L _r1 and L _r2 and flows into the DC reactor L _d . For this reason,
It does not affect the load L. Also, when GTO thyristors G ₇ and G ₁₁ are turned off, reactors L _r1 , L _r2 ,
Due to the action of L _d , the current does not suddenly become zero,
A current flows as shown by the arrow in FIG. 10 (turning on GTO thyristors _G9 and _G14 ) and charges the capacitor _Cd again. The charging pressure at this time is low. As described above, the transient voltage generated during commutation of the converter body CV ₁ is charged to the capacitor C _d with the polarity shown in Figure 9, and this charged voltage is supplied to the load L, so the transient voltage is effectively suppressed. Not only can this be suppressed, but the charging energy itself can also be used effectively.

Although the above description is an explanation of the operation of the converter main body CV ₁ , the operation of the converter main body CV ₂ is also performed in the same manner as described above. However, the DC output polarity is opposite to that in the above case, and the polarity in which switch SW ₁ is open and switch SW ₂ is closed to charge the capacitor C _d with a transient voltage is also opposite to that in FIG. And the release of charging energy of capacitor C _d is also
This is done by turning on GTO thyristors G ₁₂ and G ₈ , and the current due to the action of reactors L _r1 , L _r2 , and L _d is processed by turning on GTO thyristors G ₁₃ and G ₁₀ .

Effects of the Invention As described above, according to this invention, GTO
The electromagnetic energy of the reactance on the power supply side that is generated when PWM controlling the converter body, which is connected in antiparallel to each other and consists of thyristors, is stored in a capacitor, and the energy is supplied to the load at a predetermined time via an energy reaction circuit even during reversible operation. As a result, not only can the transient voltage generated during commutation be effectively suppressed, but also the energy can be used effectively during reversible operation, and there is no need to provide a forced commutation circuit, allowing for a more compact device. be able to. Furthermore, since it is PWM control using a GTO thyristor, it has the advantage of being able to operate with extremely high efficiency.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Figs. 2 to 7 are circuit diagrams for describing the operation of the above embodiment, and Fig. 8 is a gate drive pattern of the GTO thyristor, including output voltage and AC input. Figures 9 and 10 showing current waveforms are circuit diagrams illustrating the operation of the energy reaction circuit. CV ₁ , CV ₂ ...Converter body, DB ₁ , DB ₂ ...
...Diode bridge circuit, SW ₁ , SW ₂ ... Switch, C _d ... Capacitor, L _d ... DC reactor, L _r1 , L _r2 ... Washing winding reactor, L ... Load, G ₁ to G ₁₄ , G ₂₁ to G ₂₆ ... GTO thyristor, D ₁ to D ₆ , G ₂₁ to G ₂₆ ... diode.

Claims (1)

[Claims] 1. Consisting of a GTO thyristor, and
A pair of converter bodies that are PWM controlled and have their DC output sides connected in anti-parallel; a load connected between the output terminals of these converter bodies via a DC reactor; and a load connected to the AC input side of the pair of converter bodies separately. A pair of diode bridge circuits are connected in anti-parallel and rectify the transient voltage on the power supply side during commutation to obtain direct current with different polarities at the output. an interposed switch, a capacitor connected to the DC output side of the bridge circuit via the switch, in which electromagnetic energy on the power supply side that has rectified the transient voltage is accumulated with different polarity directions, and this capacitor and a load. A GTO thyristor converter is provided between the GTO thyristor converter and an energy reaction circuit that changes the polarity direction of the energy stored in the capacitor at a predetermined time and supplies it to the load. 2. The energy reaction circuit includes a pair of series circuit bodies formed by serially connecting GTO thyristors connected in antiparallel between both ends of a capacitor, and a common connection point of these series circuit bodies and the DC output of the pair of converter bodies. A GTO thyristor converter according to claim 1, comprising a pair of summation-wound reactances connected between ends.