JP2754205B2 - Power supply - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device that generates a high-frequency output from an AC power supply. [Prior Art] Conventionally, a power feedback type power supply has been known as this type of power supply. This conventional power supply device has a high input power factor because it does not have a smoothing capacitor in the main rectifier circuit, and furthermore, in a section where the output voltage of the rectifier circuit is lower than a predetermined voltage,
For example, since a DC voltage is supplied from the capacitor to the inverter, there is no pause and a high-frequency output with an envelope with little ripple is generated.If the discharge lamp is turned on with this high-frequency output, the lamp is lit with good luminous efficiency If this high-frequency output is rectified, a DC voltage with little ripple can be obtained. FIG. 8 shows a conventional power feedback type power supply device. Reference numeral 1 denotes an AC power supply to which a rectifier, for example, a full-wave rectifier circuit 2 is connected. A series circuit of a power storage capacitor 3 and an isolation diode 4 is connected between rectification output terminals a and b 'of the rectification circuit 2, and a push-pull inverter 5 is used as a high-frequency converter. This inverter 5 includes a primary winding 51 of an output transformer 51.
The middle point (center tap) d of p is connected to the positive output terminal a of the rectifier circuit 2, the collectors of the transistors 52a and 52b are connected to both ends of the primary winding 51p, and the resonance capacitor 53 is connected. The emitters of 52a and 52b are connected to the terminal b of the inductor 6, and the other end of the inductor 6 is connected to the negative output terminal b 'of the rectifier circuit 2. One end of each of the two windings 8a, 8b of the current limiting transformer 8 is connected to taps e, f provided on the primary winding 51p, and the other ends of the windings 8a, 8b of the transformer 8 are It is connected to a connection point c between the power storage capacitor 3 and the isolation diode 4 via the diodes 7a and 7b. For example, a discharge lamp is connected to the secondary winding 51s of the transformer 51 as a load (not shown). Note that even if the inductor 6 inserted between the terminal b 'of the rectifier circuit 2 and the emitter of the inverter 5 is removed, the characteristics of the power feedback type are not impaired. Next, the operation of the conventional device configured as described above will be described. When the AC power supply 1 is turned on, a full-wave rectified output (pulsating current output) is generated by the full-wave rectifier circuit 2, whereby the transistors 52a and 52b are alternately turned on and off by a base drive circuit (not shown) in the inverter 5. When the inverter 5 generates a high-frequency output, a rectified output is generated through a full-wave rectifier circuit including the current-limiting transformer 8 and the diodes 7a and 7b by the induced output of the primary winding 51p of the output transformer 51. Is supplied to the capacitor 3 as a feedback output. Thereby, the capacitor 3 is charged in a predetermined direction, and the capacitor 3 is discharged when the rectified output of the rectifier circuit 2 becomes lower than a predetermined voltage every half cycle, that is, in this example, the charging voltage of the capacitor 3. The output is given to inverter 5. [Problems to be Solved by the Invention] However, in this conventional technique, a current limiting transformer 8 is required as a current limiting element, so that the configuration of the device is complicated, the number of manufacturing steps is large, and the cost is high. There are problems such as that the number of components of the power feedback device is large, and when the number of turns 51p of the output transformer changes depending on the AC power supply voltage (100V, 200V), it is necessary to change the tap position of 51p. [Means for Solving the Problems] In view of the above circumstances, the present invention provides an envelope with little pause and little ripple by applying voltage feedback from an inductor inserted between a rectifier and a converter (inverter). The purpose of the present invention is to generate a high-frequency output having the following characteristics and to simplify the configuration of the device. A balanced converter for converting the output of the rectifier into a high-frequency voltage including two switching elements that alternately turn on and off at a high frequency according to the output voltage of the device;
A first inductor that is inserted between one output terminal of the rectifier and the converter and acts to flow a constant current; a connection point between one output terminal of the rectifier and the first inductor; A capacitor connected between the other output terminal of the rectifier and the capacitor connected between the other output terminal of the rectifier and the capacitor capable of supplying a charge to the converter; A switch circuit for controlling a voltage supply period to the converter, a diode inserted between a connection point between the capacitor and the switch circuit, and the converter side of the first inductor, and supplying a charging current to the capacitor; And a series circuit of the second inductor. [Operation] When the AC power is turned on and the power supply starts,
The rectifier has a pulsating voltage, and the switching element repeatedly turns on and off at a high frequency to output a high frequency. At this time, the first inductor inserted between the rectifier and the converter acts to flow a constant current, and the terminal of the first inductor has a high-frequency pulsating voltage. This high-frequency pulsating voltage is a high-frequency pulsating voltage higher by π / 2 than the instantaneous value of the output voltage of the rectifier. Then, the voltage of the difference between the output voltage of the rectifier and the high-frequency pulsating voltage of the first inductor is supplied to the capacitor as the charging voltage. Thus, when the rectified output of the rectifier falls below a predetermined voltage every half cycle, a discharge output is provided to the converter (inverter) via the switch circuit. The second inductor, which supplies charging current to the capacitor from the converter side of the first inductor (constant current inductor), protects the diode by preventing inrush power to the capacitor and limits the charging current. The input power factor of the device is prevented from lowering. Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 7. Parts common or corresponding to the conventional example are denoted by the same reference numerals. First, an embodiment of the power supply device of the present invention will be described with reference to FIG. What is different from the prior art described above is that the current limiting transformer 8 in FIG. 8 is deleted, the taps e and f and the diodes 7a and 7b are deleted, and the capacitor 3 and the isolation diode 4 (switch circuit) are removed. Is connected between two output terminals of the rectifier circuit 2 (rectifier), that is, between the negative output terminal b 'and the positive output terminal a.
Connection point c between capacitor 3 and isolation diode 4
And a diode 7 between the other end b of the inductor 6 (first inductor) having one end connected to the negative output terminal b ′.
And a series circuit of an inductor 9 (second inductor). Next, the operation of this embodiment will be described with reference to the waveform diagrams of FIGS. 2 (a) to 2 (d). When the AC power supply 1 is turned on and the power supply is started, the rectifier circuit 2
The pulsating voltage illustrated in FIG. 7A is obtained, and the transistors 52a and 52b repeatedly turn on and off at a high frequency to generate a high-frequency output as described above. At this time, the inductor 6 inserted between the negative output terminal b 'of the rectifier circuit 2 and the emitter connection terminals b of the transistors 52a and 52b of the inverter 5 functions to flow a constant current, and the terminal of the inductor 6 Is a high-frequency pulsating voltage exemplified in FIG. 2 (b). This high-frequency pulsating voltage is a high-frequency pulsating voltage higher by π / 2 than the instantaneous value Vp of the output voltage of the rectifier circuit 2. Therefore, in order to supply the capacitor 3 with the voltage of the difference between the output voltage of the rectifier circuit 2 and the high-frequency pulsating voltage of the inductor 6 as a charging current illustrated in FIG.
And a connection point c between the power storage capacitor 3 and the isolation diode 4 via the diode 7. Thereby, when the rectified output of the rectifier circuit 2 becomes equal to or lower than a predetermined voltage every half cycle, that is, the charging voltage (DC voltage) of the capacitor 3 illustrated in FIG. The discharge output is given to the inverter 5. The inductor 9 protects the diode 7 by preventing inrush power to the capacitor 3 and limits the charging current, thereby preventing a reduction in the input power factor of the power supply device. The inverter 5 in the above-described embodiment may be a self-excited type or a separately-excited type. FIG. 3 shows an example in which the inductor 6 shown in FIG. 1 is inserted between the positive terminal a of the rectifier circuit 2 and the middle point (center tap) d of the inverter 5. This is the same as the embodiment. FIGS. 4 and 6 respectively show a tap g formed by winding a coil around the inductor 6 illustrated in FIGS. 3 and 1 to increase the high-frequency pulsating voltage and to output the pulsating current of the rectifier circuit 2. This is an embodiment in which the difference from this is increased, and a higher DC voltage can be obtained than in the embodiment of FIGS. 3 and 1. FIGS. 5 and 7 show embodiments in which a tap h is provided in the inductor 6 illustrated in FIGS. 3 and 1, respectively.
A DC voltage lower than that of the embodiment shown in FIG. 1 and FIG. 1 can be obtained. The input voltage can be realized by the same method in both cases of 100V and 200V. [Effects of the Invention] As described above, according to the present invention, the above object can be achieved by applying voltage feedback from an inductor inserted between a rectifier and a converter. For this reason, it is not necessary to provide a tap on the primary winding of the output transformer of the inverter (converter), and the number of components such as a current limiting transformer can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a circuit diagram of a power supply device of the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, and (a) is an output voltage waveform diagram of a rectifier. (B) is a high-frequency pulsating voltage waveform diagram of the inductor, (c) is a charging current waveform diagram of the capacitor, (d)
FIG. 3 is a DC voltage waveform diagram of the partial smoothing portion, and FIGS.
4 and 6 are partial circuit diagrams for obtaining a DC voltage higher than that of FIG. 3 and FIG. 1, respectively.
FIGS. 5 and 7 are partial circuit diagrams for obtaining a lower DC voltage than FIGS. 3 and 1, respectively. FIG. 8 is a circuit diagram of a conventional power supply device. 1 ... AC power supply 2 ... Rectifier circuit (rectifier) 3 ... Capacitor 4 ... Diode for isolation (switch circuit) 5 ... Inverter (converter) 6 ... Inductor (first inductor) ), 7 ... diode, 9 ... inductor (second inductor), 51 ... output transformer, 52a, 52b ... transistor (switching element), 53 ... capacitor.

Claims (1)

(57) [Claims] A rectifying device that rectifies an AC voltage to output a pulsating voltage, and two switching elements that alternately turn on and off at a high frequency by the output voltage of the rectifying device. A conversion-type device; a first inductor inserted between one output terminal of the rectifier and the converter to act to flow a constant current; and connection between one output terminal of the rectifier and the first inductor. A capacitor connected between the point and the other output terminal of the rectifier and capable of supplying a charge to the converter; and a capacitor connected in series with the capacitor and the other output terminal of the rectifier. A switch circuit connected to the capacitor to control a voltage supply period to the converter by the capacitor; a connection point between the capacitor and the switch circuit;
A power supply device, comprising: a series circuit of a diode and a second inductor inserted between the inductor and the converter side to supply a charging current to the capacitor.