JPH0243414B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a circuit suitable for parallel operation of DC output power supplies, and particularly to a DC output power supply circuit provided with a smoothing capacitor on the output side.

[Prior art]

Generally, a DC output power supply circuit consists of a rectifier circuit that uses a rectifier to create DC from AC, but no matter what type of rectification signal is used, the output voltage will still contain a considerable amount of ripple. Therefore, many rectifier circuits are equipped with a smoothing circuit to remove this ripple. Smoothing circuits include a capacitor input type in which a large capacity capacitor is connected in parallel with the load device, and a chiyok input type in which a serial coil is inserted between the rectifier and the load device. The capacitor input type is often used when the load is relatively light, and has the feature that the output voltage can be higher at light loads than when only a resistor is loaded, while the choke input type is often used when the load current is large. It has the characteristic that the voltage fluctuation rate of the output voltage is good for load currents above a certain limit. Note that some rectifiers use switching elements such as thyristors to simultaneously rectify the AC power source and control the DC output voltage, and in this case, a chi-yoke coil with a sufficiently large inductance is often used in the smoothing circuit. There is.

Now, a DC output power supply circuit is usually provided for each load device, but there are cases where it is necessary to perform parallel operation in consideration of the power supply capacity for the load device and the reliability of the load device. in this case,
No problems occur during normal operation, but when one of the multiple power supply circuits that supplies power to the load device breaks down and needs to be replaced, or when a new power supply circuit for the load device is installed. When it becomes necessary to add a power supply circuit, if you connect the power supply circuit while the load device is in operation, a rush current will flow into the smoothing circuit capacitor at this time, resulting in a drop in the output voltage to the load device. A problem arises in that the load device malfunctions. Therefore, it has become necessary to once stop the operation of the power supply circuit connected to the load device to avoid this problem.

FIG. 1 is an explanatory diagram showing the main parts when operating load devices in parallel using a conventional power supply circuit. 1,
2 is a DC output power supply circuit equipped with a smoothing circuit of the Chiyoke input type; 11 and 21 are Chiyoke coils; 12 and 22 are smoothing capacitors;
3, 14, 23, and 24 indicate output terminals, and 3 is a load device.

FIG. 2 is an explanatory diagram showing a state in which an inactive power supply circuit 2 is newly connected to a load device 3 while the power supply circuit 1 is operating normally.

Now, it is necessary to add a new power supply circuit 2 to the load device 3, and if you try to connect the load device 3 while it is operating with the power supply circuit 1, the smoothing capacitor 22 has no charge, so the output terminal At the moment T ₀ when 23 and 24 are connected to the load device 3,
A rush current flows from the output terminal 13 to the smoothing capacitor 22 via the output terminal 23, and the voltage across the load device 3 temporarily drops from _V0 to _V1 .
Therefore, depending on the load device, this voltage drop may lead to malfunction, and in order to avoid such a situation, be sure to
The disadvantage was that it had to be temporarily stopped.

[Summary of the invention]

The present invention connects a resistance element in series to a smoothing capacitor provided in a DC output power supply circuit, connects a mechanical contact in parallel to this resistance element, and closes the mechanical contact when the power supply circuit is in operation. By opening the mechanical contacts when the power supply circuit is stopped, even if another power supply circuit is connected in parallel to the power supply circuit that is in operation, the load device is not affected in any way.

[Embodiments of the invention]

Now, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is an embodiment of the present invention,
Here, a schematic configuration of a DC input switching type power supply circuit is shown. 4 is the input side, 40,
Reference numeral 41 indicates an input terminal, 42 an input switch connected to the input terminal 40, and 43 an operating coil portion of a relay connected between the input terminal 41 and the input switch 42. 5 is the output side, 50 and 51 are output terminals, 52 is a chiyoke coil connected to the output terminal 50, 53 and 54 are a smoothing capacitor and a resistance element, respectively, and both are connected in series, and both ends are It is connected to output terminals 50 and 51. Reference numeral 55 denotes a mechanical contact portion of the relay, which is connected in parallel to both ends of the resistance element 54.
Reference numeral 6 denotes a switching type power conversion circuit, which is connected between the input side 4 and the output side 5.

Next, the operation of one embodiment of the present invention configured as described above will be explained. In the DC output power supply circuit shown in FIG. 3, when the input switch 42 is closed, the power conversion circuit 6 is activated and normal operation is started, and the operating coil portion 43 is energized and the relay is activated. Since the mechanical contact 55 is then closed, a smoothing circuit consisting of the choke coil 52 and the smoothing capacitor 53 is constructed, and the output voltage is stabilized. Further, this power supply circuit is stopped by opening the input switch 42, but when the input switch 42 is opened, the current in the operating coil section 43 stops flowing, the relay does not operate, and the mechanical contact 55 is opened and the smoothing A resistive element 54 is inserted in series with the capacitor 53.

Therefore, when the output terminals 50 and 51 are connected to an operating load device (not shown) for parallel operation, if the input switch 42 is left open, the output terminals 50 and 51
Even if a voltage is applied to 1, the smoothing capacitor 53
The inrush current flowing through the resistive element 54 is limited by the resistive element 54. Therefore, the voltage drop of the output voltage V ₁ at time T ₀ shown in FIG. 2 can be suppressed to an extremely low level, and will not affect the operation of the load device in any way.

〔Effect of the invention〕

By connecting a resistive element in series with the smoothing capacitor of the DC output power supply circuit, the present invention limits the inrush current when connecting another power supply circuit and operating in parallel, and the power supply can be used without causing malfunction of the load device. This allows circuits to be connected in parallel.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the main parts when the load devices are operated in parallel by the power supply circuit, Fig. 2 is an explanatory diagram showing the state when the power supply circuits are connected in parallel, and Fig. 3 is an embodiment of the present invention. FIG. 1, 2...DC output power supply circuit, 3...Load device, 4...Input side of power supply circuit, 5...Output side of power supply circuit, 6...Switching type power conversion circuit, 1
1, 21, 52... Chiyoke coil, 12, 2
2,53...Smoothing capacitor, 13,14,2
3, 24, 50, 51...output terminal, 40, 41
...Input terminal, 42...Input switch, 43...
Relay operating coil part, 54... Resistance element, 5
5... Mechanical contact part of the relay.

Claims (1)

[Claims] 1. A DC output power supply circuit equipped with a smoothing capacitor on the output side, including a resistance element connected in series to the smoothing capacitor, and a mechanical contact connected in parallel to this resistance element, and this mechanical contact is connected to the power supply circuit. A DC output power supply circuit characterized in that it is closed during operation.