JPH11285263A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power factor, by stimulating power supply from a rectifier power supply during a low-voltage period, and to use a low cost, low breakdown-voltage capacitor, by decreasing the voltage of an auxiliary capacitor. SOLUTION: A rectifier power supply 10 which rectifies the voltage of an AC power 11 and a smoothing capacitor 30 which smoothes the voltage of the rectifier power supply 19 are provided. A parallel circuit comprising an auxiliary inductor 35 and an auxiliary capacitor 39 connected in series to the smoothing capacitor 30 is provided. Also, an inverter 40 which, connected to the rectifier power supply 10, has the characteristic of intermittent input DC current, and an inductive load 50 which receives the high-frequency output of the inverter 40 are provided. The auxiliary inductor 35 and the inverter 40 act as a chopper inductor and a chopper switching element. The operation of this chopper circuit supplies power to the parallel circuit comprising the auxiliary inductor 35 and auxiliary capacitor 39. The parallel circuit improves the power factor, by performing oscillation and by stimulating the power supply from the rectifier power supply 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device including a rectified power supply for rectifying an AC power supply voltage, a smoothing capacitor for smoothing the rectified power supply voltage, and an inverter connected to a subsequent stage thereof.

[0002]

2. Description of the Related Art An inverter device of the above type is known. A high voltage period in which the rectified power supply voltage exceeds the smoothing capacitor voltage is a power supply period in which a power supply operation from the rectified power supply or the AC power supply occurs. However, a low voltage period lower than this is a non-power supply period. Generally, the power supply period is long, so that the power factor is not good. Smoothing capacitors have both the advantage of ensuring the required DC input voltage and the disadvantage of reduced power factor.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to promote a power supply operation from a rectified power supply during a low voltage period, thereby improving a power factor.

[0004]

The present invention comprises a rectified power supply for rectifying an AC power supply voltage. And a smoothing capacitor for smoothing the rectified power supply voltage. A parallel circuit of an auxiliary inductor and an auxiliary capacitor connected in series with the smoothing capacitor is provided. An inverter connected to the rectified power supply and having an intermittent DC input current. An inductive load receiving a high frequency output of the inverter is provided. The auxiliary inductor / inverter functions as a chopper inductor / chopper switching element. By the operation of the chopper circuit, power is supplied to the parallel circuit of the auxiliary inductor and the auxiliary capacitor. The parallel circuit performs an oscillating action and promotes a feeding action from a rectified power supply.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. The inverter device shown in FIG.
A rectifier power supply 10 for rectifying one voltage is provided. Rectifier power supply 10
A smoothing capacitor 30 for smoothing a voltage is provided. An auxiliary inductor 35 connected in series with the smoothing capacitor 30.
A parallel circuit of the auxiliary capacitor 35 is provided. Rectifier power supply 10
And an inverter 40 having a characteristic of intermittent DC input current. An inductive load 50 receiving the high frequency output of the inverter 40 is provided. The connection position of the input terminal of the inverter 40 is the rectified power supply 10, which is also the position across the smoothing capacitor 30 and the parallel circuit. The auxiliary inductor 35 and the inverter 40 function as chopper inductors and chopper switching elements. Power is supplied to the parallel circuit of the auxiliary inductor 35 and the auxiliary capacitor 39 by the operation of the chopper circuit. On the other hand, the parallel circuit performs an oscillating action and the rectified power supply 1
Encourages a power supply action from zero. The circuit configuration is supplemented.
The rectified power supply 10 is provided with a filter element or a filter circuit (not shown) for reducing high-frequency components synchronized with the inverter operation from returning to the AC power supply 11. The smoothing capacitor 30 is an electrolytic capacitor having a larger capacity than the other capacitors 39 and 49. The inverter 40 includes a pair of switching elements 41 and 42 connected in series, flywheel diodes 43 and 44 connected in anti-parallel with the switching elements 41 and 42, and an arm capacitor 49 functioning as a half voltage source. An example of the inductive load 50 is a fluorescent lamp lighting circuit including a fluorescent lamp, a ballast inductor connected in series to the fluorescent lamp, and a preheating capacitor connected in parallel between the non-power supply terminals of the fluorescent lamp. Another example of the inverter 40 is a vibration type inverter including a switching element, a vibration inductor in series with the switching element, and a vibration capacitor connected in parallel with either of the former. In such a case, an inductive load, for example, a fluorescent lamp lighting circuit is connected in parallel with the oscillation inductor.

[0006] The inverter 40 has a characteristic of interrupting its DC input current. The interruption is one switching element 4
It is almost the same as the intermittent operation of 1. 30 for intermittent “continuation”
A DC input current flows through the closed circuit of -40-50-49-35-30, thereby storing electromagnetic energy in the auxiliary inductor 35. When "disconnect", the auxiliary capacitor 39 is charged by discharging electromagnetic energy. By the operation of the chopper circuit, the auxiliary inductor 35 and the auxiliary capacitor 3
The energy continues to be supplied to the nine parallel circuits. The parallel circuit performs a high-frequency vibration action, and a high-frequency vibration voltage appears on the auxiliary capacitor 39. When the voltage of the auxiliary capacitor 39 has the polarity shown, the smoothing capacitor 30 and the auxiliary capacitor 3 are used.
Since the total voltage of the rectified power supply 9 exceeds the voltage of the rectified power supply 10, the non-power supply period of the rectified power supply 10 is set. In the case of the polarity opposite to that shown in the figure, the total voltage of the smoothing capacitor 30 and the auxiliary capacitor 39 tends to fall below the voltage of the rectifier power supply 10, so the rectifier power supply 10
From the power supply period. The rectified power supply 10 repeats the non-power supply period and the power supply period at a high frequency cycle. For this reason, the power factor of the rectified power supply 10 or the AC power supply 11 is improved. Consider a low voltage period in which the voltage of the rectified power supply 10 is low. Even in the low voltage period, the non-power supply period and the power supply period are repeated in a high frequency cycle. Since the power supply period is mixed there, the power factor is improved. During the low voltage period and the power supply period, the DC input voltage at the input terminal of the inverter 40 is a low voltage equivalent to the rectified power supply 10 voltage. It is a voltage that is too low for the inverter 40. However, immediately after that, the period shifts to the non-power supply period, and a high DC input voltage is formed. The average DC input voltage obtained by adding the two is an appropriate level that is not too low. The AC load 50 is an inductive load, and has an inertial effect (effect of mitigating a sudden change in current), and therefore has a DC input current (load current) substantially corresponding to the average DC input voltage. For this reason, it can be implemented without difficulty. In the non-power supply period, it is necessary to form a high voltage at the input terminal of the inverter 40 for the above-described reason. This keeps the average DC input voltage at a moderate level. The supplement for the high voltage formation is supplemented. The auxiliary capacitor 39 is the auxiliary inductor 3
5 and is charged. During the charging, the voltage of the smoothing capacitor 30 is not added. During discharging, the voltage of the auxiliary capacitor 39 is reduced to the voltage of the smoothing capacitor 30.
The voltage is added and applied to the input terminal of the inverter 40 to form a high voltage there. Thus, the auxiliary capacitor 3
9 is charged in a mode in which the voltage of the smoothing capacitor 30 is not added, and discharged in a mode in which the voltage of the smoothing capacitor 30 is added. Therefore, the voltage of the auxiliary capacitor 39 itself involved in the formation of the high voltage is relatively low, and it is possible to use an inexpensive low withstand voltage capacitor. Further, since the parallel circuit of the auxiliary inductor 35 and the auxiliary capacitor 39 is a free oscillation circuit and does not require a switching element or a diode (not shown) for appropriately regulating the oscillation action, the cost is reduced in that aspect.

[0007]

The present invention is characterized in that a parallel circuit of an auxiliary inductor and an auxiliary capacitor is connected in series with the smoothing capacitor to form an inverter having a characteristic of intermittent DC input current and an inductive load. It is assumed that. According to this, the power factor can be improved with an inexpensive circuit configuration. Further, since the smoothing capacitor voltage is not added when the auxiliary capacitor is charged, but is added when discharging, it is possible to use an inexpensive low withstand voltage capacitor. In addition, since the smoothing capacitor voltage is added to the charged voltage at the time of discharging the auxiliary capacitor, a proper average DC input voltage can be secured at the input terminal of the inverter, so that the operation can be performed without difficulty.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a device of the present invention.

[Explanation of symbols]

 10: Rectifying power supply 11: AC power supply 30: Smoothing capacitor 35: Auxiliary inductor 39: Auxiliary capacitor 40: Inverter 41: Switching element 42: Switching element 43: Flywheel diode 44: Flywheel diode 49: Arm capacitor 50: AC load

Claims (1)

[Claims] 1. A rectifying power supply (10) for rectifying a voltage of an AC power supply (11), a smoothing capacitor (30) for smoothing a voltage of the rectifying power supply (10), and a series connection with the smoothing capacitor (30). Auxiliary inductor (35) connected to
An inverter (40) having a parallel circuit of an auxiliary capacitor (39), connected to the rectified power supply (10), and having a characteristic of intermittent DC input current is provided, and receives a high frequency output of the inverter (40). An inverter device comprising an inductive load (50).