JPH02299470A - High power-factor rectifier circuit - Google Patents

Abstract

PURPOSE:To improve an input power-factor by establishing a continuity of a switching element inserted and connected between the anode of a diode and the output negative pole of a rectifier for only an appropriate short period of time immediately after an input AC voltage waveform of the rectifier passes through the zero point. CONSTITUTION:An electric current path in the state of a continuity of a transistor 9 is such that it is a single phase AC power supply 1 AC reactor 10 diode 2 transistor 9 diode 5 power supply 1, and it is energized throughout an appropriate short period of time immediately after the voltage of the power supply 1 passes through the zero point. An electric current path in the off state of the transistor 9 is such that it is a single phase AC power supply 1 AC reactor 10 diode 2 diode 6 capacitor 7 diode 5 power supply 1. Both energization modes correspond to each other when a voltage polarity of the power 1 is positive at the side of the reactor 10. ON-OFF operations of the transistor 9 are repeated every each half wave of the voltage of AC power 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rectifier circuit that is applied to an inverter or the like that uses a single-phase AC power source and is intended to increase the input power factor.

[Conventional technology]

Conventional rectifier circuits of this type are shown in Figures 4, 5, and 6.
The circuit diagrams shown in the figures are well known.

In FIG. 4, 1 is a single-phase AC power source, 2 to 5 are diodes constituting a single-phase full-wave rectifier, 7 is a smoothing capacitor, and 8 is a load.

FIG. 5 shows a configuration in which an AC reactor 10 is provided between the rectifier bridge and the AC power source 1 in FIG. 4.

FIG. 6 shows a configuration in which a DC reactor 11 is provided between the output positive electrode of the rectifier bridge and the positive electrode of the capacitor 7 in FIG. 4.

In any of the circuits illustrated in FIGS. 4 to 6 above,
The AC voltage from the power source 1 is full-wave rectified and applied to the load 8 as a DC voltage.

[Problem to be solved by the invention]

However, in the conventional rectifier circuit as described above, the input current from the AC power source to the rectifier circuit is limited to a period in which the AC power source voltage is higher than the charging voltage in the smoothing capacitor on the output side of the rectifier. An intermittent wave-like alternating current flows in a narrow phase range of the alternating current power supply voltage, and the input power factor between the input current and the alternating current power supply voltage is not good.

FIG. 7 is an operational waveform diagram of the AC power supply voltage V and the AC input current il+ in the circuit shown in FIG. The current flows as an intermittent wave-like alternating current.

FIG. 8 is an operational waveform diagram of the voltage V and the AC input current ■8□ in the circuits shown in FIGS. By adding the electromotive force to the voltage (1), the period during which the voltage on the AC power supply side is higher than the charging voltage of the smoothing capacitor is extended, and the period during which the AC input current is supplied is extended, as shown in the figure. The current Ii
The energization range of No. 2 is extended to period T3.

However, in any of the above cases, the energization range of the AC input current does not extend to the illustrated period T1, and there is a limit to the improvement of the input power factor.

In view of the above, it is an object of the present invention to provide a high power factor rectifier circuit that improves the human power factor by further expanding the energization range of the AC input current.

[Means to solve the problem]

In order to achieve the above object, the high power factor rectifier circuit of the present invention includes a single-phase AC full-wave rectifier and an AC reactor connected to the input side of the rectifier or a DC reactor connected to the output positive side of the rectifier. In a rectifier circuit having a reactor and a smoothing capacitor connected in parallel to the output side of the rectifier directly or via the DC reactor, the positive electrode side of the capacitor is the cathode side, and the output positive side of the rectifier or the DC A diode connected with the output side of the reactor as its anode side, and a switching element inserted and connected between the anode side of the diode and the output negative side of the rectifier, and the input AC voltage waveform of the rectifier is The switching element is closed only for a suitable short period of time immediately after passing the zero point.

[Effect]

As shown in FIG. 8, by providing a reactor on the input side or output side of the rectifier, it is possible to expand the energization range of AC input current from period T2 to period T3, and it is also possible to energize during period T. This makes it possible to further improve the input power factor.

In the present invention, on the output side of the rectifier, if the rectifier has an AC reactor on the input side, the positive and negative output terminals of the rectifier are connected directly, and if the rectifier has a DC reactor on the output side, A direct current switching element connects the output side of the reactor and the negative output terminal of the rectifier for a suitable short period of time immediately after the input AC voltage passes the zero point during the period T, and determines the magnitude of the capacitor charging voltage. causing a current to flow from the alternating current power supply through the glue handle and the rectifier regardless of the
The above TI, Tz, and Ty are intended to conduct electricity during the winter period. Note that the conduction time of the switching element does not need to span the entire period T1 due to the current-carrying current box i characteristics of the reactor, and may be about the first half of the period T1.

Further, in order to prevent charge discharge of the smoothing capacitor via the switching element when the switching element is conductive, a backflow prevention diode is provided between the positive electrode of the switching element and the positive electrode of the smoothing capacitor. It is something.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are circuit diagrams showing the first and second embodiments of the present invention, respectively, and FIG. 3 is an operation waveform diagram of each part of the circuit corresponding to FIGS. 1 and 2. be.

Note that in Figures 1 and 2, Figures 4, 5, and 6 are
Components having the same functions as those of the prior art embodiment shown in the figures are given the same reference numerals.

FIG. 1 shows a transistor 9 as a switching element and a diode 6 for preventing reverse current in the circuit diagram of FIG.
It has been established that

In FIG. 1, when the transistor 9 is conductive (ON), the current path is as follows: single-phase AC power supply 1 - AC realtor 10 → diode 2 → transistor 9 → diode 5 - the power supply 1, and this current flow is caused by the voltage of the power supply 1. vs is performed for a suitable short period of time immediately after passing the zero point. The current path when the transistor 9 is turned off (OFF) is as follows: single-phase AC power supply 1 → AC reactor 10 → diode 2 → diode 6 → capacitor 7 - diode 5 - the power supply 1
It will be like this. Note that this re-energization mode corresponds to the case where the voltage polarity of the power source 1 is positive on the reactor 10 side.

The ON-OFF operation of the transistor 9 is repeated for each positive and negative half-wave of the AC power supply voltage V, and an operating waveform diagram as shown in FIG. 3 is obtained with respect to the voltage (3), the AC input current, and the transistor 9.

In FIG. 3, AC input current 113 is applied to transistor 9
This is an input current that uses the AC reactor 10 as a load when it is ON, and increases during the ON period of the transistor 9, and attenuates when the transistor 9 turns OFF due to the release of the stored energy of the reactor 10. Therefore, the current I6 flowing during periods T2 and T as shown in FIG.
□ and the current 1s3 are combined to obtain a total AC input current Is4 as shown in FIG.

The current 1s4 is applied during periods T, T2, and T as shown in the figure.

The voltage V,
The power factor between the two currents is improved compared to either the current Isl or the current Isl.

Further, FIG. 2 shows the circuit diagram of FIG. 6 except that the transistor 9 and the diode 6 described above are provided, and the operation pattern of each part is almost the same as that of FIG. As shown in Figure 3.

〔Effect of the invention〕

According to the present invention, the output side of a single-phase full-wave rectifier having a reactor on the input side or output side is appropriately short-circuited and opened by a switching element, and a diode for blocking discharge current from a smoothing capacitor on the output side of the rectifier is connected. By providing this, it is possible to continue the AC input current to the rectifier during the non-charging period of the capacitor by the current that loads the reactor, and the input power factor of the rectifier is improved by improving the waveform of the AC input current. This makes it possible to reduce the rectifier capacity relative to the required power and to reduce harmonics relative to the power supply.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams showing an embodiment of the present invention, FIGS. 4, 5, and 6 are circuit diagrams showing an embodiment of the prior art, and FIG. 3 is a circuit diagram showing an embodiment of the present invention. FIG. 7 is an operation waveform diagram corresponding to FIG. 2, FIG. 7 is an operation waveform diagram corresponding to FIG. 4, and FIG. 8 is an operation waveform diagram corresponding to FIGS. 5 and 6. 1...Single-phase AC power supply, 2-6...Da□diode, 7
... Capacitor, 8... Load, 9... Transistor, 10... AC reactor, 11... DC reactor. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1) A single-phase AC full-wave rectifier, an AC reactor connected to the input side of the rectifier, or a DC reactor connected to the output positive side of the rectifier, and a single-phase AC full-wave rectifier connected directly to the output side of the rectifier or via the DC reactor. a rectifier circuit having a smoothing capacitor connected in parallel with the capacitor, a diode connected with the positive electrode side of the capacitor as its cathode side and the output positive electrode side of the rectifier or the output side of the DC reactor as its anode side; A switching element inserted and connected between the anode side of the diode and the output negative side of the rectifier is provided, and the switching element is closed only for a suitable short period of time immediately after the input AC voltage waveform of the rectifier passes its zero point. A high power factor rectifier circuit characterized by: