Electric power conversion systems – Current conversion – With condition responsive means to control the output...
Patent
1997-01-06
1998-06-23
Berhane, Adolf
Electric power conversion systems
Current conversion
With condition responsive means to control the output...
323222, H02M 7155, G05F 1613
Patent
active
057711640
DESCRIPTION:
BRIEF SUMMARY
SPECIFICATION
1. Technical Field
The present invention relates to a converter which can suppress higher harmonic currents flowing through an alternating current power supply in a power rectifier which converts the alternating current power supply to a direct current power supply.
2. Background of the Invention
As rectifying and smoothing circuits such as those used in general purpose inverters, capacitor input-type rectifying and smoothing circuits have commonly been used.
FIG. 44 shows a single-phase alternating current inputted capacitor input type rectifier and FIG. 47 shows a three-phase alternating current inputted capacitor input type rectifying and smoothing circuit.
In FIGS. 44 and 47, RF denotes a rectifier of a diode bridge type, A denotes an in-rush (rush-in) current preventive circuit, and C denotes a smoothing capacitor.
The conventional capacitor input-type rectifying and smoothing circuits have advantages such as (1) less number of parts, (2) simple in circuit construction; and (3) no need to control the converter.
Hence, this type of converter is cost effective and finds its use in a general rectifying and smoothing circuit not only limited into the general-purpose inverter.
FIG. 50 shows, for example, another type of converter which is provided with self arc extinguishing type switching elements, expect the above-described capacitor input type rectifying and smoothing circuit.
In FIG. 50, 101 and 103 denote converter and inverter constituted by the switching elements Tr and diodes D and by the same, respectively. In addition, 102 denotes a control circuit section, F denotes a carrier wave eliminating filter and Cd denotes a smoothing capacitor. The control circuit section 102 makes a direct current voltage Vd constant and controls the switching elements Tr in the converter 101 so as to form a system power supply current Is in a sinusoidal waveform using each of detection signals of a power supply voltage Vi, a converter current Ic, a direct current Id, and a load current I.sub.L detected by means of the power transformer and current transformers PT1 and CT1 through CT3 in FIG. 50.
Since the rectifying and smoothing circuits of FIGS. 44 and 47 cause the current to flow therethrough when the input voltage is higher than the direct current voltage Vd although the input waveform of the rectifying and smoothing circuit is varied according to an impedance condition of the power supply, the input waveforms of FIGS. 44 and 47 are generally shown in FIGS. 45 and 48.
These input waveforms are frequency spectrum analyzed and FIGS. 46 and 49 show results of the frequency spectrum analysis in which large lower-order higher harmonic currents flow respectively.
Such higher harmonic currents as described above flow through the power supply system so that overheating or burning-out of a system phase-lead capacitor and a DC reactor would occur.
On the other hand, the other type of converter shown in FIG. 50 can effectively suppress the higher harmonic currents in the input current waveform. However, the control circuit section 102 of the converter 101 becomes complex and many signals such as the load current detection signal, the inverter current detection signal, DC voltage detector, and DC current detection signal are required. If these detection circuits are included in the control circuit section 102, a considerable cost would disadvantageously be needed to manufacture this type of the converter as a power inverter system.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a sinusoidal wave inputted converter which can suppress higher harmonic currents and output a stable direct current voltage with a simple control circuit, in view of the above-described problems of the conventional art.
The above-described object can be achieved by providing a single-phase sinusoidal wave inputted converter comprising: a rectifier of a diode bridge connected to a single phase power supply via an input filter; a transistor circuit having a switching element and a reactor connected in serie
REFERENCES:
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patent: 5245522 (1993-09-01), Kawaguchi et al.
patent: 5489837 (1996-02-01), Arakawa
patent: 5517399 (1996-05-01), Yamauchi et al.
patent: 5532528 (1996-07-01), Lammers
patent: 5602465 (1997-02-01), Clemente
patent: 5638265 (1997-06-01), Gabor
Murai Yoshihiro
Takayama Junichi
Berhane Adolf
Kabushiki Kaisha Meidensha
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