JPS6316313Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the improvement of power supply circuits, and particularly aims to provide a power supply circuit capable of generating a plurality of DC voltages having different values.

Although various power supply circuits have been proposed in the past, it has generally been impossible to obtain a DC voltage higher than the voltage across the secondary winding of a transformer. Also, there are power supply circuits that can obtain high DC voltage, but in that case, a method such as first generating a low DC voltage and doubling it is used, so the value is a predetermined multiple of the low DC voltage. It was possible to obtain only a high voltage.

The present invention has been developed in view of the above points, and will be described below based on embodiments with reference to the drawings. 1st
In the figure, 1 is a primary winding 2 connected to an AC power source (not shown) and a secondary winding 3 whose midpoint A is grounded.
A transformer 4 includes first and second diodes 5 and 6 and a first smoothing capacitor 7 for rectifying the voltage generated between both ends B and C of the secondary winding 3 and the midpoint A. A first circuit, 8 is a first output terminal, 9 is third and fourth diodes 10 and 11 and a second smoothing capacitor for rectifying the voltage generated between taps D and E of the secondary winding 3 and midpoint A. 12 is a second output terminal; 14 is a fifth circuit whose anode is connected to the second output terminal 13;
a capacitor 16 and a sixth diode 1 connected between the diode 15 and one end C of the secondary winding 3;
7 and a third smoothing capacitor 18, and 19 is a third output terminal.

Now, if an AC voltage with the polarity shown in the figure is applied to the primary winding 2 of the transformer 1 , then the secondary winding 3
A positive alternating voltage is generated at terminal B and tap D, and a negative alternating voltage is generated at terminal C and tap E. Then, the voltage obtained at the terminal B of the secondary winding 3 passes through the first diode 5 and is smoothed by the first smoothing capacitor 7, so that a first DC voltage is generated at the first output terminal 8. Further, the voltage obtained at tap D passes through the third diode 10 and is applied to the second smoothing capacitor 1.
2, and a second DC voltage is generated at the second output terminal 13. At that time, since the terminal C of the secondary winding 3 is negative, the cathode voltage of the fifth diode 15 of the third circuit 14 has a value approximately equal to the DC voltage of the second output terminal 13, which is the same as that of the sixth diode 15. It passes through the diode 17 and is generated at the third output terminal 19.

Next, if an AC voltage of the opposite polarity to that shown in the figure is applied to the primary winding 2 of the transformer 1 , a negative AC voltage is generated at terminal B and tap D of the secondary winding 3, and a positive AC voltage is generated at terminal C and tap E.
The voltage obtained at terminal C of the secondary winding 3 is
The voltage passes through the diode 6 and is smoothed by the first smoothing capacitor 7, and a first DC voltage is generated at the first output terminal 8. The voltage obtained at the tap E passes through the fourth diode 11 and is smoothed by the second smoothing capacitor 12, and a second DC voltage is generated at the second output terminal 13. At that time, the AC voltage generated at the terminal C of the secondary winding 3 is superimposed on the AC voltage generated at the anode of the fifth diode 15 via the capacitor 16, and this voltage passes through the sixth diode 17 and is smoothed by the third smoothing capacitor 18. Therefore, the AC voltage generated at the terminal C is applied to the second output terminal 13.
As a result, a third DC voltage is generated at the third output terminal 19. FIG. 2 shows waveforms at various points in the circuit of FIG. 1.
is the AC voltage generated at terminal B of the secondary winding 3,
FIG. 2b shows the AC voltage generated at tap D of the secondary winding 3. FIG. 2C shows the AC voltage generated at tap D of the primary winding 3.
FIG. 2(d) shows the DC voltage available at the output terminal 8, where the solid line is the waveform before smoothing and the dashed line is the waveform after smoothing. FIG. 2(e) shows the DC voltage available at the third output terminal 19, where the solid line is the waveform before smoothing and the dashed line is the waveform after smoothing.
The DC voltage (dotted line) obtained by
The AC voltage available at terminal C has the form superimposed.

The waveforms of each part shown in FIG. 2 can be expressed by the following equations. That is, if the voltage obtained at the first output terminal 8 is V ₁ and the voltage obtained at the second output terminal 13 is V ₂ and the voltage drop of each diode is ignored, the voltage obtained at the third output terminal 19 is V ₃ V ₃ = V ₂ + V ₁ ...(1), and a very large DC voltage can be obtained.

The present invention can provide a power supply circuit that obtains another high voltage by changing the connection of the third circuit 14 . That is, instead of using the circuit configuration shown in FIG .
In order to use the DC voltage obtained at the output terminal 8 and the AC voltage obtained at the intermediate tap D of the secondary winding 3 as the input AC voltage, the anode of the fifth diode 15 is connected to the first output terminal 8, and the capacitor 16 If the input end of is connected to the intermediate tap D of the secondary winding 3,
A voltage of V ₄ =V ₁ +2V ₂ (2) is obtained at the third output terminal 19.

As described above, according to the present invention, a DC voltage that is sufficiently larger than the DC voltage obtained by rectifying the AC voltage generated across the secondary winding of the transformer can be generated.
It is something that can be easily obtained without loss, especially
The present invention adds the AC voltage generated at the first or second tap of the secondary winding to the first DC voltage obtained by rectifying and smoothing the AC voltage generated across the secondary winding of the power transformer. , or superimposing the AC voltage generated at one end or the other end of the secondary winding on the second DC voltage obtained by rectifying and smoothing the AC voltage generated between the first and second taps of the secondary winding. However, since rectification and smoothing are performed, it is possible to obtain a third DC voltage other than an integral multiple of the first or second DC voltage using a single transformer. Therefore, if the power supply circuit according to the present invention is used, a single power transformer is sufficient even for devices that require power supply voltages of various values, and in that case, there is no need to add intermediate taps unnecessarily. Moreover, there is an advantage that there is no need to increase the size of the power transformer.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a characteristic diagram for explaining the present invention. Explanation of main drawing numbers, 1 ...transformer, 4 ...1st
circuit, 9 ... second circuit, 14 ... third circuit.

Claims (1)

[Scope of utility model registration request] A power transformer comprising a primary winding and a secondary winding whose middle point is grounded; The circuit rectifies and smooths the alternating current voltage generated between the first tap between one end and the midpoint of the secondary winding of the power transformer and the second tap between the other end and the midpoint. A second generator that generates a DC voltage.
circuit, and an alternating current voltage appearing at the first or second tap of the secondary winding to a first DC voltage from the first circuit, or to a second DC voltage from the second circuit to the secondary winding. Consists of a third circuit that superimposes and rectifies and smoothes the alternating current voltage generated at one end or the other end of the line,
A third DC voltage having a voltage value higher than the first DC voltage and other than an integral multiple of the first or second DC voltage is obtained at the output end of the third circuit. power supply circuit.