JP2000184755A - Inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a half bridge inverter of a simple high power factor and a low cost. SOLUTION: The inverter from comprises a rectifying power source 10 for rectifying a voltage of an AC power source 11. The inverter also comprises a pair of forward series switching elements 21, 22 controlled to alternately turn ON, OFF. The inverter also comprises fly-wheel diodes 31, 32 connected in antiparallel with the elements 21, 22. The inverter also comprises a pair of series large capacity capacitors 41, 42 for arms. The inverter also comprises an inductive AC load 90 connected from a connecting mid-point of the elements 21, 22 to a connecting mid-point of the capacitors 41, 42 for the arms. The inverter supplies a high frequency power to the load 90 by connecting the power source 10, the elements 21, 22 and the capacitors 41, 42 in parallel. The inverter also comprises a auxiliary inductor 50 connected in series with a switch capacitor 42 of the capacitors 41, 42 for the arms. The inverter also comprises a small capacity auxiliary capacitor 60 connected in series or in parallel with the inductor 50 through the element 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a half-bridge type inverter device for supplying high-frequency power to an inductive AC load. The term “inverter device” is a generic term for those including a power supply circuit, an inverter, and an inductive AC load.

[0002]

2. Description of the Related Art A rectifying power supply for rectifying an AC power supply voltage, a pair of switching elements controlled to be turned on and off alternately in a series connection, a flywheel diode connected in anti-parallel with each of the switching elements, and A pair of large-capacity arm capacitors in series, comprising an inductive AC load connected between a connection midpoint between the two switching elements and a connection midpoint between the two large-capacity arm capacitors,
2. Description of the Related Art An inverter device that connects a circuit of the rectified power supply, a circuit of each of the switching elements, and a circuit of each of the large-capacity arm capacitors in parallel to supply high-frequency power to the inductive AC load is known. It is a half-half bridge type in which two sides of a bridge arm are replaced with a capacitor for a large capacity arm. In this case, since each large-capacity arm capacitor circuit functions as a smoothing circuit, it is not necessary to supplement a separate smoothing capacitor.

[0003]

The above-mentioned conventional inverter device is of a type in which a circuit of each large-capacity arm capacitor also serving as a smoothing circuit is directly connected to a rectified power supply. In such a case, the rectified power supply supplies power only during a very narrow period in which the instantaneous voltage value is almost maximum, and during that time, each large-capacity arm capacitor is rapidly charged, so that it has a low power factor type. An object of the present invention is to provide a simple and inexpensive high power factor type half-bridge type inverter device.

[0004]

The present invention comprises a rectified power supply for rectifying an AC power supply voltage. A switching element that is controlled to be turned on and off alternately in a pair of forward series. A flywheel diode connected in antiparallel with each of the switching elements. A large-capacity arm capacitor is provided in series. An inductive AC load is provided between a connection midpoint between the two switching elements and a connection midpoint between the large-capacity arm capacitors. An inverter device for supplying high-frequency power to the inductive AC load by connecting a circuit of the rectified power supply, a circuit of each switching element, and a circuit of each large-capacity arm capacitor in parallel. An auxiliary inductor connected in series with one of the large-capacity arm capacitors is provided. A small-capacity auxiliary capacitor is connected to the auxiliary inductor via one of the large-capacity arm capacitors or directly in parallel.

[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. It has a pair of switching elements 21 and 22 which are controlled so as to be turned on and off alternately. Flywheel diodes 31 and 32 connected in antiparallel with each switching element 21 and 22
Is provided. A pair of large-capacity arm capacitors 41
42. An inductive AC load 90 is provided between a connection point between the two switching elements 21 and 22 and a connection point between the large-capacity arm capacitors 41 and 42. An inverter device that supplies high-frequency power to the inductive AC load 90 by connecting the circuit of the rectified power supply 10, the circuit of each switching element 21 and 22, and the circuit of each large-capacity arm capacitor 41 and 42 in parallel. Capacitor 4 for each large capacity arm
Auxiliary inductor 5 connected in series with one 42 of first and second 42
0 is provided. A small-capacity auxiliary capacitor 60 is connected to the auxiliary inductor 50 via one of the large-capacity arm capacitors 42 or directly in parallel. FIG. 1 is supplemented. Rectifier power supply 10 is rectifier diode 1
2 to 15 are included. The switching elements 21 and 22 are transistors. An example of the flywheel diodes 31 and 32 is a parasitic diode parasitic on the transistor. The expressions of large capacity and small capacity of the large capacity arm capacitors 41 and 42 or the small capacity auxiliary capacitor 60 are relative. The large-capacity arm capacitors 41 and 42 also function as smoothing capacitors. Inductive AC load 9 shown
Reference numeral 0 denotes a lighting circuit.
And a preheating capacitor 93 in parallel with the ballast inductor 92 and the fluorescent lamp 91. 1 will be described. Each of the switching elements 21 and 22 and each of the flywheel diodes 31 and 32 are arranged in an eight-letter shape, and are turned on in the order of 21 → 32 → 22 → 31 → 21... The operation in each ON period is as follows. (1) ON period of the switching element 21 A current flows through a closed circuit of 41 → 21 → 90 → 41. As a result, the large-capacity arm capacitor 41 is discharged, and electromagnetic energy is accumulated in the inductive AC load 90. This situation continues until the switching element 21 is turned off. (2) On-period of flywheel diode 32 A current flows through a closed circuit of 90 → 60 → 32 → 90. Thereby, the electromagnetic energy of the inductive AC load 90 is released,
The small capacity auxiliary capacitor 60 is charged. This situation continues until the electromagnetic energy of the inductive AC load 90 becomes empty. By this operation, a high voltage is formed on the small capacity auxiliary capacitor 60. On the other hand, the large-capacity arm capacitor 42 is gently charged (charged in such a manner that the downward current gradually increases) via the auxiliary inductor 50, and the process shifts to the discharging operation (33) described later. (3) ON period of switching element 22 The following operations (31), (32), and (33) occur. (3
There is a sudden switch from 1) to (32). It switches slowly from (32) to (33), and in the process (32)
The operation of (33) coexists. (31) A current flows through a closed circuit of 60 → 90 → 22 → 60. Thereby, the small capacity auxiliary capacitor 60 is discharged,
Electromagnetic energy accumulates in the inductive AC load 90. At this stage, the auxiliary inductor 50 current is still down. This situation continues until the total value of the large-capacity arm capacitor 41 voltage and the small-capacity auxiliary capacitor 60 voltage decreases and becomes equal to the rectified power supply 2 voltage (instantaneous value). (32) A current flows through a closed circuit of 10 → 41 → 90 → 22 → 10. Thereby, the rectified power supply 10 is supplied (the rectified power supply 1
0), the large-capacity arm capacitor 41 is charged, and the electromagnetic energy of the inductive AC load 90 is released. (33) A current flows through a closed circuit of 42 → 90 → 22 → 50 → 42. Thereby, the large-capacity arm capacitor 42
Is discharged, electromagnetic energy is accumulated in the inductive AC load 90, and electromagnetic energy is accumulated in the auxiliary inductor 50. This situation continues until the switching element 22 is turned off. (4) On-period of flywheel diode 31 The following operations (41) and (42) proceed simultaneously. (41) A current flows through a closed circuit of 50 → 42 → 60 → 50. As a result, the electromagnetic energy of the auxiliary inductor 50 is released, the large-capacity arm capacitor 42 is discharged, and the small-capacity auxiliary capacitor 60 is charged. This situation continues until the electromagnetic energy of the auxiliary inductor 50 becomes empty. Thereafter, the current is reversed, and the current flows through a closed circuit of 60 → 42 → 50 → 60. As a result, the small-capacity auxiliary capacitor 60 is discharged, the large-capacity arm capacitor 42 is charged, and electromagnetic energy is accumulated in the auxiliary inductor 50. This situation continues until the total value of the large-capacity arm capacitor 41 voltage and the small-capacity auxiliary capacitor 60 voltage decreases and becomes equal to the rectified power supply 2 voltage (instantaneous value). Then 50 → 10 → 41
Current flows through the closed circuit of → 42 → 50. As a result, the electromagnetic energy of the auxiliary inductor 50 is released, and the rectified power supply 1
Zero power is supplied and capacitors 41 and 42 for large capacity arm
Charges. This situation continues until the electromagnetic energy of the auxiliary inductor 50 becomes empty. (42) A current flows through a closed circuit of 90 → 31 → 41 → 90. Thereby, the electromagnetic energy of the inductive AC load 90 is released, and the large-capacity arm capacitor 41 is charged. This situation continues until the electromagnetic energy of the inductive AC load 90 becomes empty. After the period (42), the operation returns to the item (1), and the following operation is repeated. Power is supplied to the rectifier power supply 10 in synchronization with the inverter operation as described above, the conduction angle of the current of the rectifier power supply 10 can be increased, and the power factor is improved. The embodiment of FIG. 2 will be described. The small-capacity auxiliary capacitor 60 of FIG. 2 is connected directly and in parallel to the auxiliary inductor 50. The connection mode is different from that of the small-capacity auxiliary capacitor 60 of FIG. 1 which is connected in parallel to the auxiliary inductor 50 via one large-capacity arm capacitor 42. However, FIG. 2 is the same as FIG. The small capacity auxiliary capacitor 60 shown in FIG.
0. Large-capacity arm capacitor 42 (composite capacitor)
Circuit. The embodiment of FIG. 3 will be described.
The small-capacity auxiliary capacitor 60 in FIG.
Are connected in parallel via a large-capacity arm capacitor 42. 3 is the same as FIG. The small capacity auxiliary capacitor 60 in FIG. 2 corresponds to the circuit of the small capacity auxiliary capacitor 60 and the large capacity arm capacitor 41 (composite capacitor) in FIG.

The present invention uses an auxiliary inductor arranged in series with a large-capacity arm capacitor and a small-capacity auxiliary capacitor connected directly or indirectly in parallel with the auxiliary inductor. According to this, an inexpensive high-power-factor half-bridge inverter device having a simple configuration can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an inverter device according to the present invention.

FIG. 2 is another similar circuit diagram.

FIG. 3 is another similar circuit diagram.

[Explanation of symbols]

 10: Rectified power supply 11: AC power supply 21 ・ 22: Switching element 31 ・ 32: Flywheel diode 41 ・ 42: Capacitor for large capacity arm 50: Auxiliary inductor 60: Small capacity auxiliary capacitor 90: Inductive AC load

Claims (1)

[Claims] A rectifying power supply for rectifying an AC power supply voltage;
A pair of switching elements controlled to be turned on and off alternately in a serial series, a flywheel diode connected in anti-parallel with each of the switching elements, a pair of large-capacity arm capacitors in series, A circuit for the rectified power supply, a circuit for each of the switching elements, and a circuit for each of the capacitors for the large-capacity arm; And an inductive device that supplies high-frequency power to the inductive AC load by connecting in parallel an auxiliary inductor that is connected in series with one of the large-capacity arm capacitors, and one of the auxiliary inductors is connected to the auxiliary inductor. A small-capacity auxiliary capacitor connected in parallel or directly through a large-capacity arm capacitor An inverter device characterized by the above-mentioned.