JPS61147740A - Power source circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a power supply circuit.

(B) Conventional technology Conventionally, a power supply circuit has been composed of a power transformer connected to an AC power supply, a rectifier circuit that rectifies the secondary output of this power transformer, and a smoothing circuit that smoothes the rectified output. It has been known.

Further, a power switch for controlling supply/cutoff of power has generally been provided on the primary or secondary side of the power transformer.

(C) Problems to be Solved by the Invention In conventional power supply circuits, for example, when the power switch is turned on at the maximum voltage portion of the sine wave of the AC power supply, noise is generated due to the sudden rise in voltage. This has caused problems such as noise to the tuner or malfunction of the microcomputer used to control the equipment.

Furthermore, the rush current caused by the sudden rise in voltage causes deterioration of switches, fuses, etc.

Furthermore, when a large transformer is used as a power transformer, the rapid magnetization caused by the sudden rise in voltage causes magnetization or unpleasant vibrations in the metal cabinet/chassis.

←) Means for solving the problem A power supply section connected to an AC power source, a zero-cross wave creation means for creating a zero-cross wave based on the AC voltage, and a control to which the zero-cross wave output from the zero-cross wave creation means is applied. means and a power switch.

(E) Effect In the above configuration, when the power switch is operated, the output from the control means is not output at the time of operating the switch, but at the rise of the zero-crossing wave (i.e., at the zero-voltage crossing point of the AC power supply). The power supply section is controlled by the control signal, thereby controlling supply and cutoff of the power supply voltage (l#) from the power supply section.

(f) Example FIG. 1 shows an embodiment of the present invention.

In Figure 1, (1) is a power transformer connected to an AC power supply, (2) is a rectifier circuit that rectifies the output voltage from power transformer (1), and (3) is a rectifier circuit that rectifies the output voltage from power transformer (1). A zero-crossing wave creating means for creating a zero-crossing wave, which includes a resistor (4) that divides the output voltage of the power transformer (1).
1 (51) and a voltage comparator (6).

(7) (81 is a Di Mitsu flip-flop which serves as a control means to which the zero-crossing wave from the zero-crossing wave generating means (3) [i.e., the output of the voltage comparator (6)) is applied; the zero-crossing wave is applied to the clock input terminal. At the same time, power switches (9) α0) are connected to the data input terminals, respectively. α1)a2 are first and second power supply units connected to an AC power supply, and are composed of a switch unit such as a relay or triac, and a power transformer (15106j).

Next, the operation will be explained.

When the power transformer (li) is connected to a commercial AC power source, such AC power (see Figure 2 (a)) is applied to the rectifier circuit (2) via the power transformer (1), and the rectifier circuit After being rectified in step (2), it is supplied as a driving voltage to a voltage ratio converter (6), D-type flip-flops (7), (8), etc.

On the other hand, the voltage at point a on the secondary side of the power transformer (1) (see Figure 2 middle) is measured by the zero-cross wave generating means (3) as shown in Figure 2 (Figure 2).
After being converted into a zero-crossing wave as shown in c), it is applied to the clock input terminal of the D-type flip-flop (7) (81).

In this state, when the power switch (9) is closed at time t1, an H level signal is applied to the data input terminal of the D-type flip-flop (7), so that the D-type flip-flop (7) The Q output is inverted and becomes H level by the rise of the zero-crossing wave that serves as the clock (i.e., at the zero-voltage crossing point of the AC power supply) (see Figure 2 (c)) (e) 8
(see).

Therefore, the Q output of this D-type flip-flop (7) closes the switch section Q3) of the first power supply section α1).
For example, at time t2 to the amplifier that constitutes the audio system.
Power supply voltage is supplied from

On the other hand, when the source switch (9) is opened at time t3, the data input terminal of the Dfi flip-flop (7) goes to the L level, so the D-type flip-flop (7) receives the zero-cross wave that serves as the clock. By the rising edge (output is inverted and becomes L level (see Figure 2 (c) and (e)))
.

Therefore, the switch section l of the 111th source section (111) is opened, and the power is cut off at time t4.

Similarly, when the power switch (10) is closed, the Q output of the D-type flip-flop (8) closes the switch section of the second power supply section (2), and for example, the switch section of the second power supply section (2) is closed. The power supply voltage is supplied to a tape recorder or the like.

Also, when the power switch α0) is opened,
The second is connected to the source U at the Q output of the D-type flip-flop (8).
The switch section α is opened and the power is cut off.

Incidentally, although the case where two power switches are provided has been described as an example, it is also possible to use only one power switch. In that case, a plurality of switch sections may be controlled by the Q output of a single flip-flop, or the number of switch sections may be one, and a power transformer or the like may be connected in parallel to the rear stage of this switch section.

Further, the input to the zero cross generation means may be obtained from the primary side of the power transformer.

(G) Effects of the Invention According to the present invention, the supply and cutoff of the power supply voltage from the power supply unit is controlled at the point of zero voltage crossing of the AC power supply, so that there is no sudden rise in voltage υ , it is possible to prevent noise from occurring when the power source is 08. Furthermore, since the rush current is reduced, fatigue of fuses, etc. can be reduced.

Furthermore, even when a large number of power transformers are used, magnetization and unpleasant vibrations do not occur.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing signal waveforms in the numbered part of the first diagram. (1) Q51 (161... power transformer, (3
)・・・Zero cross wave creation means, +71(8)・
...D-type flip-flop, (9
+(1α...Power switch, (11) (12)
······Power supply part.

Claims (2)

[Claims] (1) A power supply unit connected to an AC power supply, a zero-cross wave creation means for creating a zero-cross wave based on the AC voltage, a control means to which a zero-cross wave output from the zero-cross wave creation means is applied, and a power switch. and controlling the supply and cutoff of the power supply voltage from the power supply section at the time of zero voltage crossing of the AC power supply by a control signal output from the control means based on the operation of the power switch and the zero cross wave. A power supply circuit characterized by: (2) The power supply circuit according to claim (1), wherein the control means is a D-type flip-flop whose clock input terminal is connected to the output terminal of the zero-cross wave forming means, and whose data input terminal is connected to a power switch.