JPS63190528A - Method of switching auxiliary source - 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 [Field of Industrial Application] The present invention relates to an auxiliary power supply switching method for switching the power supply to a load from a main power supply to an auxiliary power supply during a power outage or the like.

[Conventional technology]

In recent years, loads that use microcomputers or the like for control, so-called electronics application equipment and control devices, have been increasing. Such a load requires a DC power source as its control power source, and this DC power source is generally obtained by converting a commercial frequency AC power source into DC power using a rectifier.

For these DC power sources, even an instantaneous power outage of the commercial frequency AC power source affects the normal operation of microcomputers and the like. As a countermeasure in case of such power outage, etc.,
The DC power supply has a built-in battery as an auxiliary power supply, and in the event of a momentary power outage, a voltage relay detects a drop in voltage, switches to the auxiliary power supply, and supplies the load to the load.

That is, FIG. 5 shows changes in the voltage supplied to the load during a power outage of the commercial frequency AC power supply, with the horizontal axis representing the time axis and the vertical axis representing the DC voltage supplied to the load.

Now, it is assumed that the commercial frequency AC power supply has a power outage at 21 points in the figure. The rectifier that converts commercial frequency AC power into DC has a capacitor, and because of the charge held by this capacitor, even if the commercial frequency AC power is interrupted, the DC supply voltage does not instantly go to zero; It transiently decreases with a certain time constant to P2 shown in FIG. Then, when the DC supply voltage drops to 1 shown in the figure, this voltage drop is detected by the voltage relay, and the voltage is switched to the auxiliary power supply at a further voltage drop V2. The time required for this switching Δ
t, the difference Δ■ (ΔV=VI−V2) between the voltage value ■1 at the time of detection and the voltage value ■2 at the time of switching is determined by the characteristics of the voltage relay.

[Problem that the invention seeks to solve]

However, according to such a conventional method of switching a DC power source to an auxiliary power source, a mechanical switching means called a voltage relay is used, so it is difficult to shorten the switching time Δt to the auxiliary power source. Ta. Furthermore, if an electronic switch such as a transistor is used, it is possible to shorten this switching time Δt, but if the power outage becomes longer, there is a problem that the life of the built-in battery will be shortened due to power loss within the electronic switch. Ta.

[Means for solving problems]

The present invention has been made in view of these problems, and it monitors the output voltage of the main power supply, and when this output voltage drops below a predetermined value (1), turns on the electronic switching means and controls the main power supply to the load. The power supply is switched to the auxiliary power source and continues, and when the output voltage of the main power source further decreases and the energizing voltage of the voltage relay driven by the output voltage becomes 2 or less, the voltage relay is closed normally. A contact is connected in parallel to the electronic switching means, and the output voltage of the main power source further decreases from the energizing voltage (2) to a predetermined voltage value V3.
After that, the electronic switching means is turned off and the auxiliary power source continues to supply power to the load via the normally closed contact side.

[Effect]

Therefore, according to the present invention, when the output voltage of the main power source falls below the predetermined value Vl, the electronic switching means is turned on, and the supply of power to the load is switched to the auxiliary power source and continues, and when the output voltage decreases further to the predetermined voltage value. After reaching V3, the electronic switching means is turned off, and from then on, the auxiliary power supply continues to be supplied to the load via the normally closed contact side of the voltage relay.

〔Example〕

Hereinafter, the auxiliary power supply switching method according to the present invention will be explained in detail. FIG. 1 is a block diagram of an auxiliary power supply switching circuit showing an embodiment of this auxiliary power supply switching method. In the figure, 1 is a DC power supply circuit that converts the commercial frequency AC power input through input terminals 1a and 1b into DC power, 2 is a voltage relay driven by the output power supply voltage of this DC power supply circuit 1, and 3 4 is a voltage detection circuit that monitors the output power supply voltage of the DC power supply circuit 1; 4 is an OR circuit composed of diodes DI and D2; and 5 is a logic that inputs the monitoring results in the voltage detection circuit 3 as its logical outputs E1 and E3. 6 is a charger that branches and inputs the commercial frequency AC power input through the input terminals 1a and lb, 7 is a semiconductor switch circuit, and 8 is a normally closed contact (b) of the voltage relay 2.
9 is a load, and 10 is a battery as an auxiliary power source.

The semiconductor switch circuit 7 and the normally closed contact 8 are connected in parallel, and this parallel circuit is inserted and connected in series between the positive polarity side of the auxiliary power supply 10 and the anode of the diode D2 in the OR circuit 4. The on/off operation of the semiconductor switch circuit 7 is controlled by the logic output E4 of the logic circuit 5. When the logic output E4 is "0", it is off-controlled (cut off) and when it is "1". It is controlled to be on (conducting) when Further, the logic output E4 of the logic circuit 5 is determined by its logic outputs E1 and E3 inputted via the voltage detection circuit 3, and the truth value thereof is shown in the table on the next page. As shown in the table, the logic outputs E1 and E3 of the voltage detection circuit 3 are determined by the output voltage of the DC power supply circuit 1, and when this value decreases to a predetermined voltage value Vl or less, the logic outputs E1 and E3 of the voltage detection circuit 3 are Outputs El and E3 become "1" and rOJ, and when the predetermined voltage value ■3, which is lower than this predetermined voltage value VT, becomes below, both logic outputs E1 and E3 become "1". . Further, when the output voltage of the DC power supply circuit 1 is higher than the predetermined voltage value Vl, the voltage detection circuit 3
The logic outputs E1 and E3 of the circuit are both set to "O", and EO in the table indicates the rated output voltage value of the DC power supply circuit l. In addition, the voltage relay 2 in FIG.
When the value of the driving voltage becomes less than v2, the normally closed contact 8 is closed due to a decrease in the excitation force, and the energizing voltage value 2 of the voltage relay 2 is set to the above-mentioned predetermined voltage value v3.
is set higher than vl and lower than vl (V3
<V2<Vl). Of course, this energizing voltage value v2 is determined as a characteristic value of the voltage relay 2.

Next, the operation of the auxiliary power supply switching circuit configured as described above will be explained. That is, in FIG. 1, when the commercial frequency AC power input through the input terminals 1a and lb has a power outage, the DC output voltage of the DC power supply circuit 1 changes from its rated output voltage value EO as shown in FIG. It decreases along curves PL and P2.

Here, when the DC output voltage of the DC power supply circuit l falls below ■1 as shown in FIG. , 1'' and rOJ. As a result, the logic output E4 sent out by the logic circuit 5 becomes "1", and the semiconductor switch circuit 7 is turned on by this "1" level logic output E4. That is, the DC output voltage of the DC power supply circuit 1 and the output voltage of the battery 10 are simultaneously input to the OR circuit 4, and the higher voltage of the two is supplied to the load 9.

The output voltage value of Panteri IO is set equal to the rated output voltage value EO of the DC power supply circuit 1. Therefore, in the event of a power outage of the commercial frequency AC power supply, the power supplied to the load 9 is switched to the auxiliary power supply by the battery 10. Instant switching is now possible, and compared to the conventional method that uses only a voltage relay, it is possible to reduce the voltage drop in the power supply to the load 9 at the moment of a power outage. Furthermore, the switching speed can be significantly reduced compared to the conventional method using a voltage relay.

Furthermore, the DC output voltage of the DC power supply circuit 1 decreases and ■2
Then, the excitation force of the voltage relay 2 decreases and its normally closed contact 8 closes. In other words, the closed normally closed contact 8 is connected in parallel to the semiconductor switch circuit 7 which is already in the on-drive state.
Auxiliary power from the battery 10 is supplied to the load 9 through a parallel circuit of the normally closed contact 8 and the normally closed contact 8.

When the DC output voltage of the DC power supply circuit 1 further decreases to (3), the voltage detection circuit 3 detects a voltage drop below (3), and its logical outputs E1 and E3 both become rlJ. As a result, the logic output E4 sent out by the logic circuit 5 becomes "0", and the semiconductor switch circuit 7 is turned off by this "0" level logic output E4. That is, after the DC output voltage of the DC power supply circuit 1 decreases to 3, the semiconductor switch circuit 7 is turned off, and the output voltage of the buffer relay 10 is increased only via the normally closed contact 8 side of the voltage relay 2. It is now supplied to load 9.

Therefore, even if the power outage continues for a long time after the DC output voltage of the DC power supply circuit 1 drops below ■3, the power is turned off via the normally closed contact 8 side that closes when the voltage relay 2 is deenergized. Since the supply of auxiliary power to the load 9 is continued, the subsequent power consumption in the semiconductor switch circuit 7 is eliminated, and its power loss is significantly reduced.

In this embodiment, the semiconductor switch circuit 7 was immediately turned off when the DC output voltage of the DC power supply circuit 1 reached ■3, but as shown in FIG.
The semiconductor switch circuit 7 may be configured to be turned off after a period of time τ has passed since then. With this configuration, even if there are variations in the energizing voltage (2) of the voltage relay 2, trouble-free operation can be obtained.

〔Effect of the invention〕

As explained above, according to the auxiliary power supply switching method according to the present invention, the output voltage of the main power supply is monitored, and when this output voltage falls below a predetermined value Vl, the electronic switching means is turned on, and the power supply to the load from the main power supply is switched on. Switching the supply to the auxiliary power source and continuing, the output voltage of the main power source further decreases and the energizing voltage of the voltage relay driven by the output voltage ■2
When the normally closed contact of this voltage relay is connected in parallel to the electronic switching means, the output voltage of the main power source further decreases below the energizing voltage (2) and reaches the predetermined voltage value (3). After that, the electronic switching means is turned off and the auxiliary power supply continues to supply power to the load via the normally closed contact side, reducing the speed of switching from the main power source to the auxiliary power source. In addition, the supply voltage of the main power supply can be reduced to a specified voltage value.
3, the supply of auxiliary power is continued without power via the normally closed contact side of the voltage relay, which has the unique effect of reducing power loss thereafter.

[Brief explanation of the drawing]

Fig. 1 is a block configuration diagram of an auxiliary power supply switching circuit showing an embodiment of the auxiliary power supply switching method according to the present invention, and Fig. 2 is a block diagram of the auxiliary power supply switching circuit in the case of a power outage of the commercial frequency AC power supply. A diagram showing the drop characteristics of the DC output voltage, FIG. 3 is a diagram explaining the auxiliary power supply switching operation in this auxiliary power supply switching circuit, FIG. 4 is a diagram showing another example of the auxiliary power supply switching operation, and FIG. It is a figure explaining the conventional auxiliary power supply switching operation. 1... DC power supply circuit, 2... Voltage relay, 3...
Voltage detection circuit, 5...Logic circuit, 7...Semiconductor switch circuit, 8...Normally closed contact, 9...Load, 10...
·Battery.

Claims (1)

[Claims] The output voltage of the main power source is monitored, and when this output voltage drops below a predetermined value V1, the electronic switching means is turned on, and the supply of power from the main power source to the load is switched to the auxiliary power source to continue, and the output voltage of the main power source is When the voltage further decreases to below the energizing voltage V2 of the voltage relay driven by the output voltage, the normally closed contact of this voltage relay is connected in parallel to the electronic switching means, and the output voltage of the main power source is increased. further decreases from the energizing voltage V2 to a predetermined voltage value V
3, the electronic switching means is turned off and the auxiliary power source continues to supply power to the load via the normally closed contact side.