JPH037030A - Switch device in battery backup circuit - Google Patents

Abstract

PURPOSE:To reduce the size of a diode and a loss by constructing a switch device by a first parallel circuit composed of an AC/DC power supply, a diode, a changeover contact and the like and a second parallel circuit composed of a battery power supply, a diode, a changeover contact and the like and automatically changing over the circuits. CONSTITUTION:A load 1 is connected to an AC power supply 2 via a first parallel circuit composed of a diode D1 and a relay contact (a), an AC/DC power supply 4 and an AC input terminal 3. Normally a current from the power supply is supplied to the load via the relay contact (a). When the voltage of the power supply drops, an AC relay 8 detects the voltage to change over a relay contact 7 and the load 1 is connected to a battery power supply 6 via a second parallel circuit composed of a relay contact (b) and a diode D2. A current flowing in the diodes D1 and D2 flows only in a moment wherein the relay contacts are changed over. Thus the diodes with small capacities can be used and therefore the life of the battery call be elongated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention enables switching from AC/DC power to battery power without any hindrance even if there is a power outage while using a personal computer or word processor, etc. , relates to a switching device in a battery backup circuit that can extend the life of the battery power source when using the battery power source.

[Conventional technology]

Figure 2 (a) or c) shows the conventional battery
FIG. 3 is an explanatory diagram of a backup circuit.

In Figure 2 (A), AC commercial power supply 2 is connected to load ■.
The C input terminal 3 is connected to an AC/DC power source 4 via a diode D1. Further, a battery power source 5 is connected to the load 1 via a battery terminal 6 and a diode D2. The voltage V1 of the AC power source 2 and the voltage v2 of the battery power source 5 are set such that Vl>V2. Therefore, when power is being supplied to the load 1 from the AC power supply 2, power is not supplied to the load 1 from the battery power supply 5. Further, when the AC power source 2 is out of power, current is supplied from the battery power source 5. A.C.
When the voltage of the power source 2 is restored to the specified voltage, the battery power source 5 is switched to the AC power source 2.

Note that the diodes inserted in both the AC power source 2 and battery power source 5 circuits are for backflow prevention, and current will not flow backwards to the other power source.

A timing chart when switching between the AC power source 2 and the battery power source 5 is shown in FIG. 3(A). Even if the power supply is switched in this case, there is no delay in the switching time because there is nothing other than the diode in the circuit, and the power supply voltage does not fluctuate and operates linearly.

In FIG. 2(b), an AC power source 2 and a battery power source 5 are connected to a load l via a switching contact 7. The switching contact 7 requires a relay (not shown) that detects the voltage of the AC power source 2 and controls switching of the switching contact 7.

A timing chart when switching between the AC power source 2 and the battery power source 5 is illustrated in FIG. 3 (b). In this case, the time it takes to operate the relay and complete contact switching after detecting a drop in the power supply voltage is 2 to 20 minutes.
ms, the voltage drops during the period T1 shown in the timing chart of FIG. 3(b).

In FIG. 2(c), an AC power source 2 and a battery power source 5 are connected to the load 1 via, for example, transistors TRIJ and TR2 instead of the relay contacts.

The transistors TR1 and TR2 switch the power sources by a control circuit (not shown).

A timing chart when switching between the AC power source 2 and the battery power source 5 is shown in FIG. 3(c). In this case, in order to switch the transistors TRI and TR2, it takes 1 to 2 mS from the time when the control circuit (not shown) is operated until the circuit is completely switched. A drop in voltage occurs during this period. Note that the same effect can be obtained even if an FET or SCR is used instead of a transistor.

[Problem to be solved by the invention]

However, in the conventional example shown in FIG. 2(a), not only is the control circuit unnecessary, but the power supply switching operation is linear, but backflow prevention diodes D1 and D2 with large losses are inserted in the power supply. There is.

Due to the loss caused by the current flowing through this diode, there was a problem of shortening the life of a limited capacity battery. Furthermore, since it is always connected to a load via one of the diodes, a large-capacity diode and heat radiation fins to dissipate heat from the diode are required.

In addition, in the conventional example shown in Fig. 2 (b), loss at the relay contacts is reduced, but not only does it require time to operate the relay control circuit and the relay, but it also causes a large voltage drop. arise.

Furthermore, in the conventional example shown in FIG. 2(c), the power supply switching operation time can be relatively shortened to achieve nearly linear
This has the problem of increasing the loss due to the transistor and making the control circuit more complicated than other types.

The present invention is intended to solve the above problems.
It is an object of the present invention to provide a switch device in a battery backup circuit using a relay contact with low loss and a diode with a linear power supply switching operation time and a small capacity in combination.

[Means to solve the problem]

In order to achieve the above object, the present invention focuses on the linear characteristics of diodes and the low loss characteristics of relays.

That is, the battery of the present invention.

The switch device in the backup circuit is AC/DC
A first parallel circuit consisting of a diode D1 and switching contacts a-c connected between the power source and the load, and a second parallel circuit consisting of a diode D2 and switching contacts b-c connected between the battery power source and the load. and a switching control circuit that controls the switching contact aSb that automatically switches between the AC/DC power source and the battery power source.

[Function] The load is the first parallel circuit of the diode and relay contact, and the AC
/DC power supply, and an AC power supply via the AC input terminal, the current from the power supply normally flows through the relay contacts and is supplied to the load without flowing through the diode. Furthermore, when the voltage of the power source drops, this voltage is detected and the relay contact is switched, and the load is connected to the battery power source via a second parallel circuit of the relay contact and the diode.

In this case, the time to switch the relay contacts is, i.e.
Current flows to the load through the diode only at the moment of switching, and then flows to the load through the contact.

When the voltage of the AC/DC power supply returns to normal, this voltage is detected and the relay is switched in the same manner as described above, and the load is connected to the initial state. At this time, current flows to the load via the diode until the relay contact is connected, and then flows to the load via the contact.

Therefore, the current that flows from the power source to the load flows through the diode for a short period of time after detecting the voltage until the relay contact is connected, and then flows through the relay contact to the load, so the energy dissipated in the diode is reduced. Loss is small.

〔Example〕

Fig. 1 is a schematic configuration diagram of an embodiment of the present invention. Fig. 1 (a) shows a case in which an AC relay is used to control the relay contacts, and Fig. 1 (b) shows a case in which a DC relay is used to control the relay contacts. Indicates the case where

In FIG. 1, symbols 1 to 7 correspond to FIG. 8 is an AC relay and 9 is a DC relay.

Figure 1 (a) shows a case where an AC relay 8 is used to control the relay, and the load 1 has an AC commercial power supply 2 connected to the AC input terminal 3,
It is connected via an AC/DC power supply 4 and a first parallel circuit of a diode D1 and relay contacts a-C. Further, a battery power source 5 is connected to the load 1 via a second parallel circuit including a battery terminal 6, a diode D2, and relay contacts b-c. At this time, the voltage Vl of AC power supply 2
Since the voltage V2 of the battery power supply 5 is set such that Vl>V2, when power is being supplied to the load l from the AC power supply 2, the voltage V2 of the battery power supply 5 is set such that Vl>V2.
No current is supplied to the

Further, when the AC power supply 2 experiences a power outage, the AC relay 8 detects a voltage drop in the AC power supply 2 and switches its contacts a-c to contacts b-c. That is, the time required for switching the contacts is such that current flows through the diode D2 to the load l, and then changes to the contacts b-c, which have less resistance.

Furthermore, diodes D1 and D2 inserted into both the AC power supply 2 and battery power supply 5 circuits serve to prevent backflow.

Contrary to the above, relay contacts b-c are connected from the battery power source 5.
When it is desired to supply the current that is being supplied to the load via the AC power supply 2 from the AC power supply 2, or when the power outage is restored, a predetermined voltage is applied to the AC input terminal 3 of the AC power supply 2 under the condition that Vl>V2. So, it will automatically switch from battery power source 5 to AC.
Switches to power supply 2. At this time, as before, during the switching time of the relay contacts, the current is supplied via the diode D1 and flows through this circuit to the load 1 after the relay contacts a-C are connected.

A timing chart when switching between the AC power source 2 and the battery power source 5 is shown in FIG. 3(d). In this case, even if the AC power supply 2 and the battery power supply 5 are switched, the power supply voltage does not fluctuate and operates linearly.

Next, FIG. 1(b) shows a case where a DC relay is used to control the relay contacts.

The DC relay 9 is connected after the AC power supply 2 is converted to DC by the AC/DC power supply 4. The subsequent operation is shown in Figure 1 above (
This is the same as in case b).

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments. Various design changes can be made without departing from the scope of the invention as set forth in the claims.

〔Effect of the invention〕

According to the present invention, since the load is connected to the AC/DC power source or the battery power source through the parallel circuit of the diode and the relay contact, the current flowing through the diode at the moment the power source is switched is equal to the voltage. Not only is there no drop, but the current flows through the diode for a short time, allowing the use of small-capacity diodes and eliminating the need for diode heat dissipation fins.

Furthermore, even if a rush current flows when switching the power supply, this current flows through the diode, so a small-capacity relay contact is sufficient.

Furthermore, after switching to the relay contact, current flows to the load through the relay contact without loss, which can extend the life of the battery.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of an embodiment of the present invention, Figure 2 (
3(a) to 3) are explanatory diagrams of conventional examples, and FIGS. 3(a) to 2) are timing charts. 1...Load 2...AC power source 3...AC input terminal 4...AC/DC power source 5...Battery power source 6...Battery terminal 7...Switching contact 8...AC Relay 9...DC relay (A) When using an AC relay (A) When using a diode OR circuit (B) When using a relay switch (When using a DC relay (C) TR. FET. When using a semiconductor switch such as an SCR: Schematic configuration diagram of an embodiment for Japan Figure 1 Explanation diagram of conventional example Figure 2 Timing chart Figure 111 Timing chart

Claims (1)

[Claims] A first parallel circuit consisting of a diode D1 and switching contacts a-c connected between an AC/DC power source 4 and a load 1, and a first parallel circuit connected between a battery power source 5 and the load 1. A second parallel circuit consisting of a diode D2 and switching contacts b-c; and a switching control circuit that automatically switches between the AC/DC power source 4 and the battery power source 5 and controls the switching contacts a and b. A switch device in a battery backup circuit characterized by: