JPS58179173A - Dc/ac converter by multipulse/pulse width modulation - Google Patents

Abstract

PURPOSE:Simultaneously suppress eleventh and eighteenth high frequencies of the low order high frequency while controlling the AC output voltage by deciding suitably the ON and OFF times of a switch element. CONSTITUTION:Diodes 1UD-1WD, 1XD-1ZD, 2UD-2WD, 2XD-2ZD are connected in antiparallel to GTOs 1U-1V, 1X-1Z, 2U-2V, 2X-2Z. A transformer 3 is connected in modified zigzag manner, and a transformer 4 is connected in an open star manner. A unit 20 produces a gate command to the respective GTOs. The phase of the command is decided to enable to suppress the high frequency and to control the output voltages of the converter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a DC-AC converter that obtains a constant voltage in response to fluctuations in DC input voltage and suppresses low-order harmonics on the output side.

FIG. 1 is a circuit diagram showing a conventional AC-blood flow conversion device. (IU), (IVI, (IW), (I
X).

(IY), (12), (2U), (2V), (
2W), (2X), (2Y), (2Z) i, t
, GTO Cyrisk (hereinafter referred to as GTO), which has self-erasing ability.
It is abbreviated as ), (IUD), (IVI)),
(IWD), (IXD), (1■) (IZD),
(2UD), (2VD), (8WD), (2XD
), (2Yl)), (2ZD) are respectively the above GTO
This is a diode connected in antiparallel with . (3) and (
4) are Δ-((modified staggered) (V) and Δ-(oven star) connected transformers, respectively. , (2V), (2W) cathode sides are respectively U-phase.

Phase ①, W phase, U3O phase, V2O phase, and ZSO phase.

θQ is Eko, GT to obtain the line voltage as shown in Figure 2.
O(IU), (IV), (IW'')-, (IX), (
IY), (12), (2U), (2V), (2W)
.

This is a device that sends gate cooling to (2X), (2Y), and (2Z).

When the blood applied to the anode side and the cathode side Iζ of GTO (IU) and (2X) in FIG.
U, U3O'V';30. V80 W2O.

The line h [pressure of W2O-U3O phase is shown in Fig. 2 (aJ, (b
), (c), (dl.

(e), (f) 1 above GTO (11),
(IV), (IW), (IX).

(IY), (IZ), (2U), (2V), (2W),
Using a variable θ for the on time and off time of (2X), (2Y), and (2Z), if selected, the voltage E of the secondary line Fb3 of the transformer (4) in Fig. 1 is E -y'VKEdhn2yr (shi/6-fθ), m2y
rf t +v'! ΣEd/n ,,'in 2 n
yr (1/6-fθ)-2πft.

However, fi frequency is time. Therefore, the effective value Fffl+ of the fundamental wave component and the effective value h) of the n-th harmonic component are the following f.

EfII=KEd2π(1/6-fθ)E,n,''
11hs 2 n yr (V'6-fθ) For the DC input voltage Ed=Edo, the fundamental wave voltage E(1)2E(1
There is only one θ that becomes 1. Therefore, the ratio of the DC input voltage Ed and the effective fundamental wave output i1liE(1) is determined, and after 1, the 0th harmonic E(nk
7] Varying +i1 by changing θ is as follows:
It's impossible. Therefore, as shown in Figure 1 (L, by connecting two phases, 11
It was difficult to simultaneously suppress the 18th sieve harmonic.

The present invention aims to solve the above-mentioned drawbacks by determining the on-off time of the GTO using two variables (α, β).

FIG. 8 shows an embodiment of the present invention in the case of one series. (IU), (IV), (tW), (IX
), (IY), (tZ).

(2U), (2V), (2W), (2X), (
2Y), (2VW) is GTO, (ILJD)
, (IVD), (IWI)), (IXD),
(IYI)), (IZD), (2UD).

(2VD), (2WD), (2XD), (2YD
) and (2ZD) are diodes connected in antiparallel with the GTO. (3) and (4) are respectively Δ
-1- (modified staggered) and Δ-6 (open star) connected transformers.

The cathode side of GTO (IU), (IV), (IW) is
Phase, ■ phase, W phase, GTO (2U), (2V),
The cathode side of (plot) is designated as U3O phase, V2O phase, and W2O phase. (a) In order to obtain the phase voltages as shown in Fig. 4, the above GTO, (IU), and (IV) are used.

(IW), (IX), (IY), (12), (
2[J), (2V), (2W), (2X),
(2Y).

This is a device that sends gate cooling to (2Z).

The DC input voltage applied to the anode side and cathode side of GTO (IU) and (2X) in Figure 8, respectively, is Ed.
When the above U, V, W, 080. V2
The line mjIM and pressure of O, Z80 phase are shown in Fig. 4(a), (
b), (c), (d), (e), (f
) so that + ζ re G′rO(IU), ov),
(xw), (1x), (tn, oz).

(zU>, (2V), (2W), (2X), (
The on time and off time of (2Y) and (2Z) are (α, β
), the secondary line 181 city pressure E of transformer (4) in Figure 8 is E=700KEd(1-242πfα+2pig2πfβ)excitationtπft+V'2KEdΣ -(1-2aL32πfnα
+2m2yrfnβ) Jm2πfnt. However, f
: frequency ripple, t: time.

Therefore, the effective value E fl+ of the fundamental wave component and the effective value E(n) of the nth harmonic component are as follows.

Efn=KEd (1-2m2πfα+2tu2πf
β)E(n)-KE″(1-2cotr2yrf nα
+2m2πf nβ) Here, 121 [Connection 17: The harmonics that cannot be canceled immediately are 11
Next, 1111 & , 28th order, 25th order, . . . , 12m±1st order (m== 1.2.8, . . . ) harmonics.

Here, Ed = Edll, whereas Eill = E(
The above set of (α, β), which is 11, is 1-2 α + 2 β = hllll last d1, that is, β = 43' (a. +
There are a large number of them, not just two groups [1].

Regarding the set of (α, β), in order to simultaneously suppress the 11th harmonic E (b) and the IB harmonic E (11), which are lower harmonics, the following formula v′EQη+E (to) is used. Calculate and find (α, β) whose value is the minimum. Next, E
Even when %E(1×E11)z for d=Ed2, a set of (α, β) is obtained by the same operation as above.

An example of calculation is shown in Figure 5 (a>, (b), (c). In this way, a group of (α, β ) is obtained as shown in Figure 6 of Nishiki.

In the above embodiment, the case of one connection is shown.
In the case of I@ connection, when suppressing the harmonics of 2a& and 25&, which are low-order harmonics that cannot be erased, f
This can also be applied.

Further, as the element having self-extinguishing ability, a GTO or a power transistor or the like may be used.

As described above, according to this invention, the AC output voltage can be controlled]
Since we tried to simultaneously suppress the 11th and 18th harmonics, which are low-order harmonics, without doing so, we have the effect of reducing the capacity and weight of the filter on the AC side, and making it cheaper.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing a conventional DC converter, and Figure 2 (
a), (b), (d, (d), (e)
, (f) is a voltage waveform diagram of each part of the conventional device, FIG. 8 is a circuit diagram showing an embodiment of the present invention, and FIGS. 4(a), (
b), (c), (d), (e), (f
) is a diagram of voltage waveforms at various parts in the device of the invention, FIG. 5(a). (b) and (c) are characteristic diagrams showing calculation examples of 7EQυ2+EQ3 for the 11th harmonic Eαυ and 18th harmonic E (11). It is a characteristic diagram showing a set of (α, β) of -/-t\ to suppress. In the figure, (IU), (IV), (IW), (
2U), (2V), (2W). (IX), (IY), (12), (2X), (2Y)
, (2Z) is GTOl (IUD). (IVD), (IWD), (2UD), (2VD)
, (2WD), (IXD), (IYD). (IZD), (2XD), (2YI)), (2ZD) are diodes, (3J, (41) are transformers. In each figure, the same reference numerals indicate the same or equivalent parts. 1st Figure 2 (c) W-uig culm ash (d) U30-force θj Mg Junsho (e) V3o-Wyo4M<VJj i&-g) wzo
-woaP3jafW&- ・-367- Figure 3

Claims (1)

[Claims] (1) In a DC-AC converter comprising a plurality of switch elements having self-extinguishing capability connected in series and parallel, and diodes connected in anti-parallel with each of the switch elements, the converter is connected to an n-phase converter. By making multiple connections and n-phase multiple connections, it becomes possible to suppress the harmonics of the first order (m is an integer) on mn, which could not be eliminated, and to control the output voltage of the converter. A multi-pulse device characterized by determining the on time and off time of the switch element.
DC/AC converter using Norculus width modulation.