JPH0284057A - Dc power supply - Google Patents

Abstract

PURPOSE:To prevent a high rush current from a primary power source in case of a momentary break of said primary power source, etc., by providing a switch circuit at the rush-current limiting circuit of a DC power supply and also by providing a transformer having the funtion of detecting whether there is any output of the primary power source. CONSTITUTION:When a momentary break occurs in a primary power source 1, a transistor 10 continues to operate and to supply a load 16 with a specified power while consuming the stored energy of a capacitor 9. On the other hand, the output of a transformer 26 is reduced to zero and the booth voltage of said transistor is also decreased to a value close to zero. Because a transistor 25 is turned ON consequently to short-circuit between the gate and cathode of a thyristor 6, a gate voltage is also reduced to zero. Therefore, said thyristor 6 maintains the OFF state, because there is neither input current nor gate voltage.

Description

[Detailed Description of the Invention] This invention is a DC power supply device that combines an inverter circuit and a rectifying and smoothing circuit to obtain a DC output. This relates to an inrush current prevention circuit whose purpose is to prevent fuses in the human power line of a DC power supply from blowing out or the contacts of an open/close switch from welding due to the inrush current that flows in such a case.

[Conventional technology]

Figure 3 is a configuration diagram of a conventional DC Ti source device (1)
is a primary power supply that supplies AC power, (2) is an on/off switch to protect the primary power supply (1) from abnormalities in the DC power supply, (3) is a group of diodes to convert AC input to DC, (4) is a control circuit for controlling the voltage supplied to the load (16), (5) is a current limiting resistor that limits the peak value of the current flowing to the capacitor (9), and (6) is a current limiting resistor ( (7) and (8) are resistors and diodes to supply the auxiliary winding output of the transformer (11) to the gate of the sirisk (6), and (9) is the A capacitor for supplying pulsed power to the transformer (11) according to the switching operation of the transistor (10), (10) is the transformer (11)
A transistor that turns on and off the current flowing through (
II) is a transformer, (12), <13) is a diode that rectifies the secondary winding output of the transformer (11), (1
4) (15) is the diode (12), the choke coil and capacitor that smooth the output of (+3), and (16) is the load.

In a conventional device of this kind, AC power supplied from a primary power source (1) is converted into DC power by a diode (3), and then converted into pulsed power by a transistor (10) and a transformer (11). Power is transmitted to the secondary side of 11). Transformer (if the voltage is stepped down or stepped up to the specified voltage by I), a diode (12), (1
After rectification in 3), a choke coil (14),
The voltage smoothed by the capacitor (+5) and supplied to the load (16) is monitored by the control circuit (4), and by controlling the on/off period of the transistor (10),
It has been stabilized.

Here, FIG. 4 shows the waveforms of various parts in the DC power supply device configured as shown in FIG. 3 when an instantaneous interruption occurs after normal input is applied.

(A) is the primary power supply voltage waveform, (B) is the capacitor (9)
, (1) is a gate signal waveform of the thyristor (6), and (1) is an input current waveform diagram from the primary power source (1).

As shown in the first half of the waveform diagrams (A) to (1), if two-person power is turned on normally, the current from one person will flow through the current-limiting resistor (5) to charge the capacitor (9). The peak value determined by (5) will not be exceeded. Then, after the capacitor (9) is sufficiently charged, the transistor (10) starts operating.
) is supplied to the gate of the thyristor (6), and even if the thyristor (6) is turned on, no large inrush current will flow. In addition, since the input current after turning on Cyrisk (6) flows through Cyrisk (6), the current limiting resistor (5)
) will be eliminated.

Here, as shown in the latter half of the waveform diagrams (A) to (1).

If a momentary interruption of the primary power supply (1) occurs, the transistor (
10) continues to operate while consuming the energy stored in the capacitor (9), so the signal continues to be output to the gate of the thyristor (6), and the moment the primary power is restored, the waveform (1 ), a large capacitor charging current designated I□P flows through the thyristor (6). Therefore, the welding diode group (3) of the open/close switch (2)
This has the disadvantage of causing problems such as damage to the parts.

[Problem to be solved by the invention]

The inrush current prevention circuit in conventional DC power supplies is configured as described above, so when the primary power supply (υ) is momentarily interrupted or when a manual switch is turned on and off in a short period of time,
Since the inrush current prevention circuit does not operate sufficiently, an excessive current flows in the input line, causing problems such as welding of the open/close switch (2) and damage to the diode group (3).

The present invention was made to solve this problem, and relates to improving the characteristics of an inrush current prevention circuit.

[Means to solve the problem]

The DC power supply device according to the present invention prevents IF from inrush current flowing when a momentary power outage occurs in the primary power supply (1).
A transformer (26) that obtains a predetermined voltage from the voltage generated by the primary power supply (1) and a switch circuit (+8) that turns on/off the gate input voltage of the SIRISK (6) are added.

[Effect]

In this invention, by providing the DC power supply with a transformer (26) that obtains a predetermined voltage based on the output voltage of the primary power supply (1) and a switch circuit (18) that turns on and off the gate voltage of the thyristor (6), This prevents inrush current from flowing when a momentary interruption occurs in the primary i-source (1).

〔Example〕

FIG. 1 shows one embodiment of this invention, and (1) to (16)
is the same as or equivalent to the above conventional device, (17)
is the Cyrisk inrush current limiting circuit, (1g) is the switch circuit, (19), (20) are the diodes, (21)
), (22), and (23) are resistors, (24) is a capacitor, (25) is a transistor, and (26) is a transformer.

In the DC power supply configured as described above, AC power supplied from the primary power supply (1) is supplied to the diode group (3
) is converted to direct current. Further, the energy stored in the capacitor (9) is transmitted to the secondary side of the transformer (11) by the on/off operation of the transistor (10) connected to the primary winding of the transformer (11).

Then, it is rectified by a diode (12) and a diode (13), and a choke coil (14) and a capacitor (1
5), power is supplied to the load (16).

On the other hand, immediately after AC power is applied from the primary power source (1), the AC power is rectified by the diode group (3), and voltage is applied to the anode side of the thyristor (6), but no voltage is applied to the gate of the thyristor (6). Therefore, the thyristor (6) is in the off state. For this purpose, the capacitor (9) is connected to the resistor (
5), and no large rush current flows to the capacitor (9). After that, when the capacitor (9) is charged to a predetermined voltage, the transistor (1G) is turned on and off by the operation of the control circuit (4), and the transformer (1G) is turned on and off by the operation of the control circuit (4).
Pulse power is supplied from 11) and a voltage is applied to the gate of the thyristor (6) through the diode (8) and resistor (7). At this time, the secondary winding output of the transformer (26) is rectified by the diode (19) and diode (20),
A voltage is supplied to the booth of the transistor (25) through the resistor (21). Since this booth voltage is greater than the emitter voltage, the transistor (25) is in an off state. Therefore, the thyristor (6) is turned on and power is supplied through the thyristor (6). Such normal operation is the same as that of a conventional DC power supply.

Here, FIG. 2 shows the waveforms of various parts in the DC power supply device configured as shown in FIG. 1 when a momentary interruption occurs after normal input is applied.

(A) is the voltage waveform of the primary power supply (1), (B) is the voltage waveform of the capacitor (9), (1) is the gate voltage waveform of the thyristor (6), (1) is the booth of the transistor (25) A voltage waveform, (o) is a diagram showing an input current waveform from the primary power source (1).

If the input is normally turned on from the primary power supply (1), the capacitor (9) is charged by the resistor (
5), the input current from the primary voltage #(1) never exceeds the peak value determined by the resistor (5).

Here, as shown in Figure 2 (a), the primary power source (1
), the transistor (10) continues to operate and continues to supply a predetermined power to the load (16) while consuming the energy stored in the capacitor (9).

On the other hand, the output of the transformer (26) becomes zero and becomes (1) in Figure 2.
), the boost voltage of the transistor also becomes almost zero. For this reason, the transistor (25) turns on and short-circuits the gate and cathode of the two-channel transistor (6), so that the gate voltage also becomes zero as shown in (1) of FIG. Therefore, the thyristor (6) maintains an off state since there is no input current and the gate voltage is also zero.

Next, when the input from the primary power supply (1) is restored, the output from the transformer (26) charges the capacitor (24) through the resistor (21), increases the booth voltage of the transistor (25), and When (25) is turned off, a voltage is applied to the gate of Cyrisk (6), and Cyrisk (6) is turned on again. Primary power supply (
1) is restored and the thyristor (6) is turned on, the capacitor (9) is charged through the resistor (5), and even when the primary power supply (1) is restored after a momentary interruption, the capacitor (9) is charged. , no large inrush current flows through the capacitor (9). Note that the time it takes for the primary power supply (1) to recover after a momentary interruption and for the thyristor (6) to turn on is determined by the resistor (21),
(22), determined by the value of the capacitor (24).

In this way, even if a momentary interruption occurs in the primary power supply (1), a large inrush current will not flow to the capacitor (9), and problems such as damage to the diode group (3) or welding of the open/close switch contacts will occur. Occurrence can be prevented.

In the above embodiment, the output of the primary power source (1) is described as being a l-phase AC power source, but similar effects can be expected in the case of a three-phase AC power source. Further, similar effects can be expected for push-pull type DC power supplies that use a plurality of transistors (1G) as switching elements.

〔Effect of the invention〕

As explained above, this invention provides a switch circuit (18) in the inrush current limiting circuit (17) of a DC power supply, and
By providing a transformer (26) that has the function of detecting the presence or absence of the output of the secondary power source (1), in the event of a momentary interruption of the IQ power source (1), a large inrush from the primary Ti source (1) can be detected. This has the effect of preventing the occurrence of problems such as damage to the diode group (3) and welding of the contacts of the open/close switch (2).

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a circuit of a DC power supply device to which the present invention is applied, Fig. 2 is a diagram for explaining the invention in detail, Fig. 3 is a diagram showing an example of a conventional circuit, and Fig. 4 is a diagram showing an example of a conventional circuit. FIG. 3 is a diagram showing the operation of a conventional circuit. In the figure, (1) is the primary power supply, (2) is the on/off switch, and (3
) is a group of diodes, (4) is a control circuit, (5) is a resistor,
(6) is a thyristor, (7) is a resistor, (8) is a diode, (9) is a capacitor, (10) is a transistor, (
11) is a transformer, (12) is a diode, (13)
is a diode, (14) is a choke coil, (15)
is the capacitor, (+6) is the load, (17) is the Cyrisk inrush current limiting circuit, <18> is the switch circuit (19)
) is a diode, (20) is a diode, (21)
is resistance (22) is resistance, (23) is resistance, (24)
is a capacitor, (25) is a transistor, (28)
is trans. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A control circuit that detects a voltage supplied to a load and controls the pulse width of a pulse signal, a switch element that performs a switch operation based on an output signal of the control circuit, and one end of a primary winding connected to one end of the switch element. , at least one or more 2
a transformer having a secondary winding; a capacitor connected to the other end of the primary winding of the transformer to supply a pulse current; a thyristor inrush current limiting circuit for preventing inrush current to the capacitor; and an AC input. a plurality of diodes that rectify power and supply output to the thyristor inrush current limiting circuit; a plurality of diodes, choke coils, and capacitors that rectify and smooth the secondary winding output of the transformer; and a thyristor of the thyristor inrush current limiting circuit. A DC power supply device comprising: a switch circuit that opens and closes a gate input voltage; and a transformer whose primary winding is connected to an AC input power source and whose secondary winding is connected to the switch circuit.