JPH0449862A - Gto inverter device - Google Patents

Abstract

PURPOSE:To reduce energy loss by providing snubber resistance, an electric valve for checking reverse currents, and first and second auxiliary power sources so as to withdraw the energy of a snubber and a current limiting reactor. CONSTITUTION:An electric valve 62, which is connected in series with snubber resistance 61, is provided between the junction of a snubber capacitor 31 and a snubber diode 41 and the junction of a snubber capacitor 32 and a snubber diode 42 so that the snubber energy when the gate turn-off thyristors (GTO) 11 and 12 of the arms in a pair 1 are converted from ON to OFF can be returned to load. Moreover, first and second auxiliary power sources 5 and 6 are connected in series to the plus side and the minus side of the arms in a pair 1, and outer sides of the snubber resistance 61 and the electric valve 62 are connected to the first and second auxiliary power sources 5 and 6, respectively, so that the energy and snubber energy, which are stored in current limiting reactors 51 and 52 when the electric valve 62 is ON or OFF in accordance with the ON OFF operation of GTO 11 and 12, may be withdrawn by returning them to the auxiliary power sources 5 and 6. Hereby, energy loss can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is based on the GTO (Gate Turn off T
The present invention relates to a GTo inverter device that uses a power converter (hyri-stor) and recovers energy from a snubber circuit provided for the purpose of suppressing noise and absorbing surges due to electrostatic coupling and electromagnetic induction.

[Conventional technology]

Figure 9 shows, for example, Mitsubishi Electric branch shaft Vo1.61, NQl
l, 1987. Conventional G shown in P63-P68 ultra-high speed variable speed electric motor system (MELDRIVE series)
It is a circuit diagram showing the configuration of a TO inverter device, in which 4 is a DC power supply and 100°200.300 is an inverter arm pair. A detailed circuit of the inverter arm pair is shown in FIG.

11.12 is the GTO121, 22 is the freewheeling diode, 31.32 is the first. The second snubber capacitor, 41.42, is the first snubber capacitor. second snubber diode, 51
．． 52 is a current limiting reactor coupled to a center tap system;
81 is a CT (current transformer), and 91 to 94 are diodes forming a bridge circuit.

Here, the first
snubber capacitor 31 and first snubber diode 41
The series circuit of the second snubber capacitor 32 and the second snubber diode 41 is called a snubber circuit.

Also, GTOII, freewheeling diode 21
and the parallel circuits of the snubber circuits 31 and 41 are connected to the upper arm UA,
The parallel circuit of the GTO 12, freewheeling diode 22, and snubber circuit 32.42 is called a lower arm S^.

Next, the operation will be explained. First, in the circuit shown in FIG. 10, when a load current flows as a forward current in the GToll of the inverter arm pair 100, for example, in the path of the DC power supply 4 → GTO 11 → current limiting reactor 51 → load (not shown), the GToll When the load current is turned off, the load current becomes the first
Snubber capacitor 31 → first snubber diode 41
→ Path of current limiting reactor 51 and second snubber capacitor 32 → CT81 → Diode 91 → DC power supply 4 → Diode 94 → CT81 → First snubber diode 41 →
The current flows through the path from the current limiting reactor 51 to the load and charges the first snubber capacitor 31.

Further, the energy discharged from the second snubber capacitor 32 is recovered by the DC power supply 4.

Next, when the load current is flowing in the path of freewheeling diode 22 → current limiting reactor 52 → load, GTOI
The second snubber capacitor 32 is charged while being current-limited by the current-limiting reactors 51 and 52 coupled in a center-tapped manner. At this time, the same amount of energy as the charging energy is stored in the current limiting reactor.

This energy is circulated through the path of current limiting reactors 51, 52 → second snubber diode 42 → CT81 → diode 91 → DC power supply 4 → diode 94 → CT81 → first snubber diode 41 → current limiting reactor 51.52. , is recovered to the DC power supply 4. The electric charge of the first snubber capacitor 31 is discharged through the path of the first snubber capacitor 31-+current limiting reactor 5, 52→CT81→diode 91→DC power supply 4→diode 94→CT81→first snubber capacitor 31. However, that energy is recovered by the DC power supply 4.

[Problem to be solved by the invention]

Since the conventional GTO inverter device is constructed as described above, it requires a large-capacity CT and requires time to reset the CT, so it cannot be used for high frequency switching of several hundred hertz.

Although in principle it is possible to recover 100% of the snubber energy, in practice there is a problem that the loss in CT etc. is large and the recovery rate cannot be improved.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to obtain a GTO inverter device equipped with a snubber circuit that is E-type and can also be used in high-frequency circuits.

[Means to solve the problem]

The GTO inverter device according to the present invention has a positive side arm in which a snubber circuit including a first snubber capacitor and a first snubber diode is connected in parallel to the GTO, and a pair of the positive side arm. An inverter arm pair consisting of a negative side arm connected via a current reactor, the inverter arm pair connected in parallel to a DC power supply, and a connection between the first snubber capacitor on the positive side and the first snubber diode. a resistor connected in series between the point and the connection point of the second snubber capacitor on the negative side and the second snubber diode, and an electric valve for current check when recovering the snubber energy to an auxiliary power source; a first auxiliary power source connected in series with the same polarity to the positive side of the auxiliary power source, and a second auxiliary power source connected in series with the same polarity to the negative side of the first auxiliary power source; Furthermore, diodes are connected from the negative side of the second auxiliary power supply to the connection points of the positive side snubber circuit of the snubber resistor to recover energy from the snubber and the current limiting reactor, thereby enabling high frequency operation. It is composed of

[Effect]

The GTO inverter device of this invention is provided with an electric valve connected in series with a snubber resistor between the connection points of the snubber capacitor and the snubber diode on the positive side and the negative side, so that the GTO of the arm pair is turned from ON to OFF. In addition, the first auxiliary power source and the second auxiliary power source are connected in series to the positive and negative sides of the pair of arms, and the snubber resistor and both ends of the electric valve are connected by a diode. After that, the above 1. It is connected to the second auxiliary power source and controls the electric valve in accordance with the ON/OFF operation of the GTO so that the energy and snubber energy stored in the current limiting reactor at the time of ON and OFF can be returned to the auxiliary power source and recovered.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as in FIG. 2 are designated by the same reference numerals. In FIG.
, and 6 is a second auxiliary power source.

Also, Figure 2 is a detailed circuit diagram of inverter arm pair 1,
61 is a resistor, 62 is an electric valve, and in this embodiment, a GTO is used. 71 and 72 are diodes for current reversal when the snubber energy is recovered from the power source.

Next, the operation will be explained. First, the time chart of the electric valve 62 is shown in FIG.
The electric valve 62 is turned OFF at the timing when either of 2 is turned OFF.
Do N. And GTO II.

The electric valve 62 becomes 0 at the timing when any of the 12 is turned on.
FFL repeats the operation of turning on again for a time T3 after a certain time T2 has elapsed.

First, GTOll is ON, current flows in the forward direction, and the G
The case where TOII is turned off will be explained. Figure 4 shows the distribution route at this time.

That is, if GTOII is turned off at time t0,
Load current j flowing through GTOll. is the current main 1 and i,
It runs for about 2 minutes. Current i charges the first snubber capacitor 31. At the same time, the electric charge of the second snubber capacitor 32, which was charged to the power supply voltage value, is turned on when the electric valve 62 is turned on.
Therefore, the current flows back to the load through the resistor 61.Next, we will explain the case where the current flows in the opposite direction and turns on the GTO 12. The state of the distribution route at this time is shown in FIGS. 5 to 7. First, turn on GTOll at 1 time t1°
do. The load current i3 flowing through the freewheeling diode 22 flows through the GTOll, and the second snubber capacitor 32 is charged by current i4 flowing through resonance with the current limiting reactor 51, 52 connected in a center tap manner. Ru. After the second snubber capacitor 32 is charged, the energy stored in the current limiting reactor 51, 52 is recovered to the first auxiliary power source 5 via the current reverse diode 71 along the path of the current is.

Subsequently, the electric valve 62 is turned on at time t1□ after time T2.

The time T2 and the voltage of the auxiliary power source are determined so that the current i is attenuated by this time.

When the electric valve 62 is turned on at time t, the energy of the first snubber capacitor 31 becomes a current as shown in FIG.
It is discharged along the path and accumulated in the current limiting reactors 51 and 52. Further, when the electric valve 62 is turned off at time t, 2 after T3, the energy of the current limiting reactor 51, 52 is transferred to the first auxiliary power source 5 through the path 17 in FIG.
1 and then collected.

Note that if the OFF time of the electric valve 62 is short and the time T3 cannot be taken, the electric valve 62 may be controlled as shown in FIG.

Further, although a GTO is used as the electric valve, a self-exciting type such as a transistor may be used, and the same effect as in the above embodiment can be obtained.

Further, in the above embodiment, the inverter has three phases, but it may be single phase or other phases.

The same effects as in the above embodiment are achieved.

〔Effect of the invention〕

A resistor and an electric valve are connected in series between the connection point between the positive side snubber capacitor and the snubber diode and the connection point between the negative side snubber capacitor and the snubber diode, and a first auxiliary power source is connected to the positive side of the DC power source. are connected in series with the same polarity, and a second auxiliary power source is connected in series with the same polarity to the negative side of the DC power source, and the positive side of the first auxiliary power source is connected to the anode pole of the electric valve, In addition, a diode is connected from the negative side of the second auxiliary power supply to the connection point between the positive side of the snubber resistor and the snubber circuit to recover energy in the snubber circuit, eliminating the need for a large-capacity CT and making it compact. This has the effect of providing a GTO inverter device that can also be adapted to high frequency operation.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit configuration diagrams of a GTO inverter according to an embodiment of the present invention, Figure 3 is a time chart showing the operation of the GTO and electric valve, and Figures 4 to 7 are details of the present invention. Fig. 8 is a time chart showing another control example of the electric valve, Fig. 9 and Fig. 10 are the conventional GTO
FIG. 2 is a configuration diagram of an inverter. In the figure, 1 to 3 are inverter arm pairs, 4 is a DC power supply, 5 is a first auxiliary power supply, 6 is a second auxiliary power supply, 11,
12 is a GTO, 31 and 32 are snubber capacitors, and 41.
42 is a snubber diode, 51.52 is a current limiting reactor, 61 is a resistor, 62 is an electric valve, 71.72 is a diode, UA is an upper arm, and SA is a lower arm. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant: Mitsubishi Electric Corporation Figure 2 *1 Figure Figure Figure Figure First page

Claims (1)

[Claims] A circuit in which the upper arm and the lower arm are connected by a center-tapped current limiting reactor, and a first snubber circuit for the upper arm.
The intersection of the snubber capacitor and the first snubber diode,
and a circuit in which an electric valve and a series resistor are connected between the intersection point of the second snubber diode and the second snubber capacitor of the snubber circuit of the lower arm for controlling when recovering the snubber energy to an auxiliary power source, which will be described later. an inverter arm pair consisting of; a DC power supply having a plurality of inverter arm pairs arranged in parallel and connected in the forward direction to the GTO of the upper and lower arms;
A first auxiliary power supply connected in series in the forward direction to the positive pole of the DC power supply, and a second auxiliary power supply connected in series in the forward direction to the negative pole of the DC power supply.
an auxiliary power supply, a current flowing between the positive terminal of the first auxiliary power supply and the second snubber diode, and the negative terminal of the second auxiliary power supply and the anode of the first snubber diode in the opposite direction during energy recovery. G equipped with a check diode
TO inverter device.