JPH0545086Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[0001]

[Field of Industrial Application] This invention relates to a distributed uninterruptible power supply device used in electronic registers and the like.

[0002]

[Prior art] The adoption of POS (point of sale systems) has increased due to the rationalization of sales management at shopping stores, etc., and the installation of compact uninterruptible power supplies (hereinafter referred to as UPS) for power outage protection has increased. are doing. In such applications, there is a tendency to use a method of distributing small UPSs for each register for reasons such as ease of expansion, dispersion of failures, and reduction of initial investment.

[0003] A conventional UPS will be explained with reference to a block system diagram in FIG. 7 and an operating waveform diagram in FIG. 8. When the commercial power supply is normal, the commercial power applied to the input terminal 1 is supplied to the output terminal 3 via the switch means 2 (on between a and c). During this time, the charger 4 rectifies a part of the commercial power to charge the storage battery 5. The load (electronic register) is turned off at time t ₁ due to the closing of the shopping store (Fig. 8A),
At time _t2 during the night, the input commercial power of the UPS is forcibly turned off (FIG. 8B). In other words, for the purpose of fire prevention in shopping stores, etc., the power mains are shut off all at once at night, except for the minimum necessary loads such as refrigerators, and the input power to the UPS is also shut off. The on/off switch of the UPS is also turned off at time t ₁ when the load is turned off, or at time t ₂ when the trunk lines are all cut off. However, if you forget to turn off the UPS, the power outage detector 6 detects the input power cutoff at time _t2 , and the power outage detector 6 provides a high-level detection signal B to the control circuit 7 (Fig. 8B). When the control circuit 7 receives the detection signal B, the control circuit 7 controls the switch means 2 using the control signal C to change over the switch, turn on b and c (FIG. 8C), and drive the inverter 8. The power of the storage battery 5 is converted into AC power by the inverter 8 (FIG. 8D), and the AC voltage is supplied to the output terminal 3 via the switch means 2 (FIG. 8D).
E).

[0004] The next morning, when the power supply main line is turned on at time _t3 , the output B of the power failure detector 6 becomes a low level, the switch means 2 is switched to turn on between a and c, and the inverter 8 is turned on. It is considered off. At time _t4 , shortly before the store opens the next morning, the load (electronic register) is turned on.

[0005] If a power outage occurs at time _t5 , the output B of the power outage detector 6 is set to a high level, the switching means 2 is switched so that between b and c is turned on, and the inverter 8 is turned on. AC power is supplied to the output terminal 3 in place of the commercial power supply. During a power outage, if the cash register where the UPS is placed is out of service for some reason between time t ₆ and t ₇ , the power switch of the electronic cash register is turned on during this period, and the UPS is turned on.
We are trying to reduce power consumption.

[0006] If the power outage is restored at time _t8 , the output of the power outage detector 6 is set to a low level, the switching means 2 is switched on between a and c, and the inverter 8 is turned off and the commercial power is turned on again. Power is applied to output terminal 3.

[0007]

[Problem that the invention attempts to solve] Conventional UPS
If you forget to turn off the UPS at the time when the load is turned off after closing (t ₁ ) or when the main lines are all cut off (t ₂ ), then at the time t ₂ to _{t 3} when the main lines are all cut off. Over time, the inverter 8 is turned on and no-load operation losses occur. The no-load operation loss is a loss that occurs mainly in the transformer, switching transistors, and filters inside the inverter 8 during no-load operation. Therefore, the power of the storage battery 5 is wasted. Assuming that the current storage battery has the capacity to supply power to the load during a power outage of about 30 minutes, the storage battery 5 will almost lose its ability to supply power to the load about 10 hours after the main line is shut off. If a power outage occurs shortly after the store opens the next day, the storage battery 5 has not yet been sufficiently charged and the voltage has not been restored, and the time that power can be supplied to the load will be short (for example, 10 minutes), and the 30-minute It may become impossible to cope with power outages, causing great disruption to cashier operations.

[0008] When the main line is collectively cut off for a long time (for example, 15 hours), the storage battery 5 is operated under no load during this period and becomes over-discharged, significantly shortening its lifespan. When the load (electronic register) is turned off, the UPS
There would be no problem if the electronic register could be turned off, but electronic registers are already installed and provided for service, and there are various manufacturers of them, so it is difficult to modify electronic registers just because you are installing a new UPS. In many cases, it is not allowed to do so, thus giving rise to the above problem.

[0009] In order to eliminate such problems, during a power outage or when the main lines are all cut off, the presence or absence of load current is checked, and if the load current cannot be detected, it is determined that the load is not connected and the inverter 8 is operated. It is possible to prevent this from happening. By doing this, the inverter 8 can be operated during a power outage,
From the state in which the output of the inverter 8 is supplied to the load to operate the load, once the operation of the load is stopped,
Even if the load is disconnected and then the load is connected again during the power outage to operate the load, the load current will not flow, resulting in the problem that the inverter cannot be automatically operated.

[0010]

[Means for solving the problem] According to this invention, there is a load current detector that detects the presence or absence of a load by detecting the alternating current flowing through the load, and a load current detector that determines whether the voltage of the storage battery is higher than a reference value. When a load current detector detects the presence of a load during a power outage and the voltage of the storage battery is above the reference value, AC power at the commercial power frequency is continuously supplied to the load. During a power outage, if the presence of a load is not detected by the load current detector and the voltage of the storage battery is above the reference value, AC power at the commercial power frequency is intermittently applied to the load. A control circuit is provided to drive the inverter to supply the power for a short period of time.

【0011】

Embodiment An embodiment of this invention will be described with reference to the circuit system diagram in FIG. 1 and the operation waveform diagram of each part in FIG. 2. Components corresponding to those in FIG. 7 are given the same reference numerals, and redundant explanation will be omitted. Switch means 2 and output terminal 3
A load detection means 9 is provided between the two and the load detection means 9 for detecting the presence or absence of a load. Further, the voltage of the storage battery 5 is applied to a comparator 10 and compared with a reference voltage E _r to determine whether or not it exceeds the reference voltage. The outputs of the load detection means 9 and the comparator 10 are both given to the control circuit 7.

[0012] Similar to the conventional example, the load is turned off at time t ₁ due to the closing of the store (FIG. 2A), and during the night time
It is assumed that the main line is cut off at t ₂ . Generally, the UPS is also turned off at this time t ₁ or t ₂ , but let's assume that you forget to turn it off. In the load detection means 9, a CT (current transformer) 9 is connected to the path from the switch means 2 to the output terminal 3.
a is inserted, and a voltage proportional to the load current is extracted and applied to the load current detector 9b. This voltage is compared with a reference value in the load current detector 9b. If it is above or below the reference value, it is determined that the load current exists or does not exist, respectively.
A detection signal D at a high level or a low level is applied to the off-delay circuit 9c. When the off-delay circuit 9c receives the high-level detection signal D, it immediately outputs the high-level signal E. However, even if the detection signal D falls to a low level, the output E does not fall immediately, but after a delay time Δ (for example, 1 This is a circuit in which the voltage falls after 2 seconds).

[0013] When the output D of the load current detector 9b falls at time _t1 (FIG. 2D), the off-delay circuit 9
The output of c falls after Δ time (FIG. 2E). In the control circuit 7, an AND circuit 7c performs an AND operation between the detection signal B of the power failure detector 6 and the output signal of the comparator 10, and when the AND is successful, a high-level output signal F is provided to the inverter drive circuit 7d.
Further, the output E of the off-delay circuit 9c is directly supplied to the select terminal of the inverter drive circuit 7d. The inverter drive circuit 7d drives the inverter 8 when the output F of the AND circuit 7c is at a high level, and at this time, if the output E of the off-delay circuit 9c is at a high level, it performs continuous driving, and when it is at a low level, it performs intermittent driving. .

[0014] In other words, when a power outage is detected and a load current exists immediately before the power outage, and the voltage of the storage battery 5 is equal to or higher than the reference value, the inverter drive circuit _7d is turned on. There is no load current in the output E of the off-delay circuit 9c.
is a low level (Fig. 2E), and the output F of the AND circuit 7c
is at a high level (Fig. 2F), the inverter drive circuit 7d is driven intermittently (Fig. 2F'), and the inverter 8
is driven intermittently (Fig. 2G). The control circuit 7 is provided with a buffer circuit 7a. Buffer circuit 7a
When receiving a high-level detection signal B from the power failure detector 6 at time _t2 , it applies a control signal to the switch means 2 to switch the movable contact c from the fixed contact a to the fixed contact b side. However, since the inverter 8 is driven intermittently as described above, the AC power is only intermittently supplied to the output terminal 3 little by little (FIG. 2J).

[0015] The next morning, when the main power supply is turned on at time _t2 , the output B of the power failure detector 6 becomes a low level (FIG. 2B), and the movable contact c of the switch means 2 is switched to the fixed contact a side. (FIG. 2C), and commercial power is applied to the output terminal 3 (FIG. 2J). When the load is turned on at time _t4 prior to closing (FIG. 2A), the output D of the load current detector 9b goes to a high level (FIG. 2D), and the off-delay circuit 9c
The output E of is also at a high level (FIG. 2E). However, since the output B of the power failure detector 6 remains at a low level (FIG. 2B), the output F of the AND circuit 7c also remains at a low level (FIG. 2F), and the inverter 8 is not driven (FIG. 2G).

[0016] Immediately after the store opens, if a power outage occurs at time _t5 , the output B of the power outage detector 6 becomes a high level (FIG. 2B), and the movable contact c of the switch means 2 is switched to the fixed contact b side. (Figure 2C). Further, the output D of the load current detector 9b falls to a low level. However, since the off-delay circuit 9c has a fall delay time Δ, its output does not fall immediately but maintains a high level. Main line bulk shutdown period
Since the storage battery 5 is not driven by the inverter 8 from t ₂ to _{t 3} and no power is consumed, at time t ₅ the voltage is generally higher than the overdischarge determination reference voltage E _r and the output of the power failure detector 6 is also at a high level. Therefore, the output F of the AND circuit 7c is at a high level, and the output E of the off-delay circuit 9c is also at a high level, so the inverter drive circuit 7d performs continuous driving (FIG. 2F').
The inverter 8 operates continuously (FIG. 2G), and the AC voltage of the inverter 8 is supplied to the output terminal 3 (FIG. 2J). As a result, the output D of the load current detector 9b
is returned to a high level again (FIG. 2D), and the output of the off-delay circuit 9c continues to be at a high level (FIG. 2D).
E).

[0017] During a power outage, if the cash register where this UPS is placed is suspended (of course, some other cash registers are in operation), in order to prevent wasteful power consumption of the UPS (storage battery), the load (electronic register) is turned off at time t ₆ (FIG. 2A). The output D of the load current detector 9b becomes a low level, and the output E of the off-delay circuit 9c becomes a low level after Δ time (FIG. 2E). As a result, the output F of the AND circuit 7c is at a high level, but the off-delay circuit 9c is at a low level, and the inverter drive circuit 7d is in an intermittent drive state, and the intermittent pulses a, b, with a period T (for example, 2 to 3 seconds), c and d are inverter drive circuit 7
d (FIG. 2F'), the inverter 8 is driven, and the corresponding pulse voltages a', b', c', and d' are output (FIG. 2G). Depending on the pulse voltages a', b', and c', the load is off, so the corresponding load current does not flow, and the output D of the load current detector 9b is at a low level. When the load is turned on at time t ₇ (Fig.
A) Load current flows due to the immediately following pulse voltage d′,
The output D of the load current detector 9b and therefore the output E of the off-delay circuit 9c become high level, and the inverter drive circuit 7d performs continuous driving.

[0018] FIG. 3 shows an example of the inverter drive circuit 7d.
Shown below. The operation of this circuit will be explained with reference to the operational waveform diagram of FIG. The clock pulse (FIG. 4C) generated by the clock generator 30 is frequency-divided by 1/n by the frequency divider 31 (FIG. 4D), and this frequency-divided wave is given to a rising differentiation circuit 32 and a falling differentiation circuit 33. The respective differential outputs (FIGS. 4E and F) are provided to the switch circuit 34.

On the other hand, the clock panel is also applied to a T-type flip-flop 35, and a Q output whose polarity is inverted at the rising edge of the clock pulse is applied to the switch circuit 34 (FIG. 4I). On the other hand, the switch circuit 34 is controlled by the Q output of the RS flip-flop circuit 36. The RS flip-flop circuit 36
is reset by the output E of the off-delay circuit 9c, and is also set by the ANDed signal of the inverted signal of the output E and the ORed signal of the output of the rising differentiation circuit 32 and the output of the falling differentiation circuit 33. (Figure 4G). Flip-flop 36 is at time t ₆
After +Δ, it is set by the first set pulse, and a high level output is given to the switch circuit 34 to switch the switch to the side a in the figure (FIG. 4H). The output of the switch circuit 34 is given to the AND circuits 37 and 38 together with the output F of the AND circuit 7c.
The outputs of 38 are given to drivers 39 and 40, respectively, and the outputs of drivers 39 and 40 (Fig. 4J,
K) F', F'' are supplied to the inverter 8.

[0020] FIG. 5 shows that when the commercial power supply is normal, the commercial power supply is rectified by the charger 4, the rectified output is used to charge the storage battery 5, and the power of the storage battery 5 is converted to AC power by the inverter 8 and supplied to the load. However, an embodiment is shown in which this invention is applied to a UPS that converts the power of the storage battery 5 into AC power using an inverter and supplies it to the load during a power outage.

[0021] FIG. 6 shows that when the commercial power supply is normal, it is supplied to the load and is rectified by the inverter 8 to charge the storage battery 5. During a power outage, the switch means 2 is turned off and the power of the storage battery 5 is transferred to the inverter 8. A method was adopted in which the AC power was converted to AC power and then supplied to the load.
This figure shows an example of applying this idea to a UPS. The embodiments shown in FIGS. 5 and 6 are both similar to the embodiment shown in FIG. 1, so a description thereof will be omitted.

【0022】

[Effects of the invention] According to this invention, even if you forget to turn off the UPS when turning off the load (electronic register) due to store closing or when cutting off the power mains all at once at night, the power mains will be turned off. During the shutdown, the UPS inverter is turned off or operated intermittently, so the no-load operation loss is zero or very small, and therefore most of the energy from the storage battery is wasted as in the conventional case. This means that even if a power outage occurs immediately after the store opens the next morning, it can be adequately dealt with. In addition, there is no risk that the storage battery will be over-discharged during the bulk main line shutdown period at night, which will shorten the life of the storage battery.

[0023] During a power outage, the inverter is operated intermittently even during the period when the load is off, so similarly, the power of the storage battery is almost never wasted, and a long power outage can be coped with. In addition, if the power outage continues for longer than the UPS compensation time and the voltage of the storage battery drops below the standard value, the inverter will stop driving, so there is no risk of the storage battery becoming over-discharged and shortening its lifespan.

[0024] Moreover, even when there is no load during a power outage,
Since the inverter is operated intermittently, when a load is connected, a load current flows, and a load current detector detects the connection and puts the inverter into a continuous drive state, automatically putting the load into an operating state.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram showing an embodiment of this invention.

FIG. 2 is an operation waveform diagram for explaining the operation of FIG. 1;

FIG. 3 is a circuit diagram showing an example of an inverter drive circuit.

FIG. 4 is an operation waveform diagram for explaining the operation of FIG. 3;

FIG. 5 is a block system diagram showing another embodiment of this invention.

FIG. 6 is a block system diagram showing still another embodiment of the invention.

FIG. 7 is a block system diagram showing a conventional uninterruptible power supply.

8 is an operation waveform diagram for explaining the operation of FIG. 7. FIG.

[Explanation of symbols]

1...Input terminal 2...Switch means 3...Output terminal 4...Charger 5...Storage battery 6...Power outage detector 7...Control circuit 8...Inverter 9...Load detection means 10...Comparator 11...Load.

Claims (1)

[Scope of utility model registration request] [Claim 1] In an uninterruptible power supply device that converts power from a storage battery into AC power using an inverter and supplies it to a load when a power outage of a commercial power source is detected, the AC current flowing through the load is detected to detect the presence or absence of a load. a load current detector that compares the voltage of the storage battery with a reference value and determines whether the voltage is higher than or equal to the reference value; a load current detector that detects the presence of a load during a power outage; When the voltage of the storage battery is higher than the reference value, the inverter is driven to continuously supply AC power with the commercial power frequency to the load, and in the event of a power outage, the load current detector detects the presence of the load. and a control circuit that drives the inverter so as to intermittently supply AC power having a commercial power supply frequency to the load for a short time when the voltage of the storage battery is equal to or higher than a reference value. Features an uninterruptible power supply.