JP5572352B2 - Uninterruptible power system - Google Patents

Description

  The present invention relates to an uninterruptible power supply that discharges energy stored in a battery when a power failure occurs in an AC input power supply and charges the battery when power is restored from the AC input power supply. It is related with the uninterruptible power supply which can keep the discharge energy from a constant value as much as possible.

  Patent Document 1 discloses an uninterruptible power supply as a power supply for stably supplying AC power to an important load such as a computer. This discharges the energy stored in the battery at the time of a power failure of the AC input power supply and supplies this discharge energy to the load so that the power can always be supplied even at the time of the power failure of the AC input power supply. The battery is charged when the AC input power is restored (normal).

  In an uninterruptible power supply having such a configuration, it is important to manage the battery so that the battery is always normal and its life can be maintained for a long time.

  Hereinafter, a conventional uninterruptible power supply that is considered in this regard will be described with reference to FIGS.

  FIG. 5 is a schematic configuration diagram for explaining a first example of a conventional uninterruptible power supply. The discharge voltage of the battery 20 is detected by the voltage detector 12, and the detected voltage and the end-of-discharge voltage setting device 55 are detected. The end-of-discharge voltage determined in (1) is compared by the comparator 50, and the chopper gate signal 60, which is the output of the comparator 50, is supplied to the step-up / step-down chopper 8.

  In FIG. 5, the converter 3 is stopped during a power failure of the AC input power supply 31, and the step-up / step-down chopper 8 is discharged to discharge the battery 20. As the discharge progresses, the discharge voltage of the battery 20 gradually decreases, and this discharge voltage is detected by the voltage detector 12, and this detected voltage falls below the discharge end voltage set by the discharge end voltage setting unit 55, and the comparator The chopper gate signal 60 which is an output of 50 changes from 1 to 0, and the step-up / step-down chopper 8 stops the discharging operation.

  Here, the end-of-discharge voltage is the lowest voltage that can be allowed by the battery 20 during discharge, and its value is exclusively a constant value irrespective of the discharge current (discharge time rate).

  In addition to the configuration described above, FIG. 5 shows the main configuration of the uninterruptible power supply between the AC input power supply 31 and the load 32, which is the input switch 1, the input filter 2, and converts AC power into DC power. Converter 3, DC electrolytic capacitor 4, inverter 5 for converting DC power to AC power, and output filter 6 are connected, and these input filter 2, converter 3, DC electrolytic capacitor 4, inverter 5, and output filter 6 are connected in series. In parallel, a bypass switch 7 is connected, and a DC reactor 9 is connected between the step-up / step-down chopper 8 and the battery 20.

  FIG. 6 is a schematic configuration diagram for explaining a second example of the conventional uninterruptible power supply. This is the same as FIG. 5 in the main configuration of the uninterruptible power supply, but the discharge end voltage of FIG. Instead of the setting device 55, an output current sensor 10 that detects a current input to the load 32, and a discharge end voltage regulator that outputs a discharge end voltage corresponding to the output current sensor 10 by inputting the detection current of the output current sensor 10. 56 is provided.

  In FIG. 6, the basic operation at the time of a power failure of the AC input power supply 31 is the same as that in FIG. In FIG. 6, when the output current of the uninterruptible power supply is low, the discharge current of the battery 20 is also low. In general, when the discharge current is low, the voltage of the battery slows down, and the battery is in a deep discharge state in which the energy (battery voltage × discharge current × discharge time) that can be extracted from the battery before the end of discharge is large. In this case, the battery 20 may take a long time for the recovery charge, or in the worst case, the battery 20 may be damaged such that the recovery charge cannot be performed. Since the discharge current is roughly proportional to the output current of the uninterruptible power supply, the output current of the uninterruptible power supply is detected by the output current sensor 10 and the discharge current of the battery 20 is discharged as the output current decreases by the discharge end voltage regulator 56. A deep discharge state can be avoided by setting the end voltage high and making the energy that can be extracted from the battery 20 as constant as possible regardless of the magnitude of the output current.

  FIG. 7 is a schematic configuration diagram for explaining a third example of the conventional uninterruptible power supply, in which the output of the battery current sensor 11 for detecting the current of the battery 20 and the battery detection detected by the voltage detector 12 are illustrated. The voltage is input to the discharge power integrator 57, the discharge power calculated by the discharge power integrator 57 and the discharge end energy setting device 58 are compared by the comparator 50, and this comparison result is given to the step-up / step-down chopper 8. It is composed.

  In FIG. 7, the basic operation at the time of a power failure of the AC input power supply 31 is the same as that in FIGS. In FIG. 7, the discharge energy can be calculated by time-integrating the product of the battery current obtained by the battery 20 and the battery current sensor 11 by the discharge power integrator 57 regardless of the output current of the uninterruptible power supply. As a result of comparing the allowable discharge energy designated by the discharge end energy setting device 58 with the comparator 50, the discharge of the battery 20 can be stopped if the discharge energy exceeds the allowable value, regardless of the magnitude of the output current. A deep discharge state can be avoided by making the energy that can be extracted from the battery 20 as constant as possible.

JP 2006-109603 A

  The conventional example shown in FIG. 5 is a so-called one-dimensional uninterruptible power supply device in which the discharge end voltage is set to a constant value, and this has the following problems. That is, since the discharge end voltage of the battery 20 is uniformly monitored only when the battery voltage is being discharged, the discharge energy of the battery 20 increases greatly until the discharge ends when the discharge current is small (light load). Therefore, there is a problem that it takes time for the recovery charge after the power recovery of the battery 20, or in the worst case, the battery 20 is damaged such that the recovery charge cannot be performed.

  The conventional example shown in FIG. 6 is a so-called two-dimensionally managed uninterruptible power supply device in which the discharge end voltage is increased as the output current is lower, and this has the following problems. That is, since the discharge end voltage of the battery 20 can be manipulated according to the magnitude of the output current, deep discharge can be avoided. Since the output current sensor 10 is mostly provided as an uninterruptible power supply for the purpose of overcurrent protection and overload protection of the inverter 5, there is an advantage that deep discharge can be avoided by using existing components. However, when a plurality of (for example, 2 to 5 parallel) batteries 20 are connected in parallel as in the case where the additional battery 21 in FIG. 6 is added, even if the output current of the uninterruptible power supply is near the rated current. For each battery 20 connected in parallel, the discharge current is low, and eventually the discharge energy of the battery 20 is large and the battery 20 is in a deep discharge state. Therefore, the same problem as in the conventional example of FIG. 5 cannot be completely avoided in the conventional example of FIG.

  The conventional example shown in FIG. 7 does not compare the battery voltage and the end-of-discharge voltage, but integrates the discharge power of the battery 20 over time, so as to stop the discharge when the allowable end-of-discharge energy is exceeded. This is a managed uninterruptible power supply, which has the following problems. That is, even if the bank of the additional battery 21 is connected in parallel to the bank of the permanent battery 20, the discharge current is shunted, and the current sensor 11 for each battery bank can detect the discharge current for one battery bank. The discharge power integrator 57 can also estimate the discharge energy for one battery bank. Therefore, deep discharge of the bank of the battery 20 or the bank of the additional battery 21 can be essentially avoided. However, the conventional example of FIG. 7 requires a current sensor 11 for each battery bank when the number of parallel batteries is 2 to 5, for example, and the discharge power integrator 57 has a battery bank that changes as the discharge time elapses. Since the voltage and current must be integrated and calculated at extremely short time intervals, the control circuit is heavily burdened with arithmetic processing, and in some cases, an additional processor may be required.

  The present invention has been made to solve the above-described problems, and is a configuration that is newly added using existing circuit components regardless of the magnitude of the output current supplied to the load or the parallel connection configuration of the batteries. An object of the present invention is to provide an uninterruptible power supply that can more reliably avoid deep battery discharge without increasing the number of elements.

In order to achieve the above object, the invention corresponding to claim 1 is based on a power converter that converts AC power into DC power and converts DC power into AC power when the AC input power supply is normal. A battery charging / discharging circuit that supplies AC power to the load and charges the battery, and that can stop supply of the discharged power of the battery to the load via the power converter when the AC input power is out of power. In the uninterruptible power supply
A discharge voltage detecting means for detecting a discharge voltage of the battery;
Charging time measuring means for measuring the charging time of the battery;
A discharge time measuring means for measuring the discharge time of the battery;
The discharge end voltage can be converted with respect to the discharge time of the battery, and by inputting the net discharge time, the discharge end voltage converting means for outputting the discharge end voltage with respect to the net discharge time, and
Input the measured charging time that is the output of the charging time measuring means and the measured discharging time that is the output of the discharging time measuring means, and subtract the measured charging time from the time required for full charging to calculate the time required for full charging. The time is converted into the discharge time, and the measured discharge time is added to obtain the net discharge time. The net discharge time is equivalent to the time when the battery is discharged from the fully charged state. A charge / discharge time converter for inputting as a net discharge time of the discharge end voltage conversion means,
The discharge end voltage, which is the output of the discharge end voltage conversion means, is compared with the detected discharge voltage detected by the discharge voltage detection means. Comparing means for outputting a discharge stop command for
It is an uninterruptible power supply characterized by comprising.

  According to the present invention, regardless of the magnitude of the output current supplied to the load or the parallel connection configuration of the battery, the battery can be deeply discharged without increasing the number of newly added components using existing circuit components. To provide an uninterruptible power supply that can avoid the problem more reliably.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram for demonstrating Embodiment 1 of the uninterruptible power supply device of this invention. The schematic block diagram for demonstrating the principal part of FIG. The schematic block diagram for demonstrating Embodiment 2 of the uninterruptible power supply device of this invention. The schematic block diagram for demonstrating the principal part of FIG. The schematic block diagram for demonstrating the 1st example of the conventional uninterruptible power supply. The schematic block diagram for demonstrating the 2nd example of the conventional uninterruptible power supply. The schematic block diagram for demonstrating the 3rd example of the conventional uninterruptible power supply.

  Hereinafter, Embodiment 1 of the uninterruptible power supply apparatus according to the present invention will be described with reference to FIGS. 1 and 2. Here, the same components as those in FIGS. Therefore, the description is omitted.

  When the AC input power supply 31 is normal, the load 32 is converted via a power converter (for example, a converter 3, an inverter 5, and a DC electrolytic capacitor) that converts AC power into DC power and converts DC power into AC power. A battery charge / discharge circuit (for example, the step-up / down chopper 8) that supplies the AC power to the battery 20 and charges the battery 20 so that the AC input power supply 31 can supply the discharge power of the battery 20 to the load via a power converter when a power failure occurs. And an uninterruptible power supply device having a circuit including a DC reactor 9).

  That is, a discharge voltage detecting means for detecting the discharge voltage of the battery 20, for example, a discharge voltage detector 12, a discharge time measuring means for measuring the discharge time of the battery 20, for example, a discharge time counter 52, and a discharge end voltage with respect to the discharge time of the battery 20 By inputting the discharge time measured by the discharge time counter 52, discharge end voltage conversion means for outputting a discharge end voltage for this discharge time, for example, a discharge end voltage converter 51, and a discharge end voltage converter The discharge end voltage which is the output of 51 and the detected discharge voltage detected by the discharge voltage detector 12 are compared, and when the detected discharge voltage is equal to or lower than a predetermined value, specifically, the step-up / down chopper 8 is supplied to the battery 20. Comparing means, for example, a comparator 50, for outputting a discharge stop command, for example, a chopper karate signal 60, for stopping the discharge. That.

  The end-of-discharge voltage converter 51 is created by testing a plurality of different types of batteries, or by making a simulation or creating a data database in an actual device. The discharge end voltage converter 51 of FIG. 1 shows an example. The discharge end voltage is constant from the beginning to a predetermined time, and the discharge end voltage gradually increases every time the discharge time elapses thereafter. The characteristics are as follows. Actually, this characteristic may be a linear function or a quadratic function.

  FIG. 2 is a schematic diagram for explaining the control circuit 500 of the uninterruptible power supply apparatus conventionally used with the embodiment of FIG. 1, and has the following configuration. The input voltage detection circuit 501 that detects the input voltage of the AC input power supply 31 and the power failure detection level set by the power failure detection level setting unit 503 are compared by the comparator 502 to detect a power failure. The power failure detection logic in this case is “1”, the AC input power supply 31 indicates a power failure, and “0” indicates the AC input power supply 31 is normal. In the control circuit 500, a crystal oscillator 504 that outputs a reference clock pulse and a counter for maintenance diagnosis of the battery 20 based on the reference clock pulse from the crystal oscillator 504 are used as a discharge time counter 52 for comparison. The discharge start timing based on the output of the detector 502 is used as a trigger for starting counting. The discharge time measured by the discharge time counter 52 configured as described above is input to the discharge end voltage converter 51.

  According to Embodiment 1 of the present invention, the following effects can be obtained. When the AC input power supply 31 is interrupted and the battery 20 starts to be discharged, the discharge time counter 52 measures the discharge time and gives the discharge time 61 to the discharge end voltage converter 51. In general, the control circuit of the uninterruptible power supply apparatus is preliminarily equipped with a discharge time measuring means capable of measuring time such as a microcomputer, and means corresponding to the discharge time force counter 52 can be easily realized.

  When the current of the load 32 is low or when the discharge current of the battery 20 is low due to the addition of the additional battery 21 in FIG. 6 or the like, the discharge time becomes long, so the discharge end voltage converter 51 gradually stops the discharge. Set the voltage higher.

  Thereby, the comparator 50 gives the step-up / step-down chopper 8 a signal for stopping the discharge at a voltage higher than the constant discharge end voltage as shown in the first embodiment.

As a result, the battery 20 stops discharging the battery 20 in a time earlier than the first and second conventional examples described above. In this case, among the means for detecting the product of discharge voltage × discharge current × discharge time and the product of discharge voltage × discharge current, the output current sensor 10 shown in FIG. Even if the battery current sensor 11 shown in FIG.
As a newly added component, the discharge end voltage converter 51 alone can reduce the discharge time as appropriate, and the discharge energy until the battery 20 reaches the end of discharge can be kept substantially constant. Therefore, according to the first embodiment of the present invention, three-dimensional management is performed as in the conventional example shown in FIG. 7, and no components such as the battery current sensor 11 and the discharge power integrator 57 are required. Similarly to the above, deep discharge of the battery 20 can be avoided more reliably, and the number of components can be reduced, which is advantageous in reducing the cost of the product.

  Next, Embodiment 2 of the uninterruptible power supply apparatus of the present invention will be described with reference to FIGS. 3 and 4. The same components as those already described with reference to FIGS. 5 to 7 and Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

FIG. 3 is a schematic configuration diagram for explaining Embodiment 2 of the uninterruptible power supply device of the present invention,
Here, as in the first embodiment, the discharge time 61 is not simply followed, but the discharge voltage 61 is appropriately manipulated with the charge time 62 taken into account to expedite the discharge during charging. In the first embodiment, the charging time counter 53, the full charge time setting unit 54a, the comparator 54b, the plus limiter 54c, and the constant unit 54d are arranged so that the end voltage is raised and the deep discharge prevention of the battery can be realized with better accuracy. A charge / discharge time converter 54 having an adder 54e is added.
Specifically, as shown in FIG. 4, a connection circuit between the output terminal of the comparator 502 and the input terminal of the discharge time counter 52 is branched halfway to provide an inverter 505, and the charge time counter 53 is connected to the output terminal of the inverter 505. The charge time 62 that is the output of the charge time counter 53 and the discharge time 61 that is the output of the discharge time counter 52 are input to the charge / discharge time converter 54.

  In Embodiment 2 having such a configuration, when the battery 20 has not reached full charge during recovery charging in the past, the charging time 62 until the discharge starts again is measured by the charging time counter 53. The charge / discharge time converter 54 is given.

  The charge / discharge time converter 54 obtains the time required for full charge by subtracting the charge time 62 from the time required for full charge, converts this time to equivalent to the discharge time, and adds it to the new discharge time 61. A net discharge time 63 is obtained. This net discharge time 63 corresponds to the time when the battery 20 is discharged from the fully charged state. If the battery 20 has already reached full charge, the time required for full charge in the previous period is zeroed by the limiter and is not added to the discharge time 61.

As described in the first embodiment, the discharge end voltage converter 51 gradually sets the discharge end voltage higher in accordance with the net discharge time 63 as the discharge time elapses.

  As described above, the battery 20 can keep the discharge energy until the end of the discharge substantially constant even if the discharge is in the middle of charging by adjusting the discharge end voltage according to the net discharge time 63.

  Accordingly, in the second embodiment, as in the first embodiment, the performance of the uninterruptible power supply can be improved without increasing the number of components, and deep discharge of the battery 20 can be avoided directly, thereby extending the life of the battery 20. Can do.

In the embodiment described above, the discharge energy J is a time integral of the product of the discharge voltage V and the current I. Therefore,
J = ∫ (V · I) dt≈V · I · T
However, instead of stopping the discharge according to the voltage-current product V · I, the discharge energy J can be monitored equivalently if the discharge stop is advanced as the discharge time T extends.

DESCRIPTION OF SYMBOLS 1 ... Input switch, 2 ... Input filter, 3 ... Converter, 4 ... DC electrolytic capacitor, 5 ... Inverter, 6 ... Output filter, 7 ... Bypass switch, 8 ... Buck-boost chopper, 9 ... DC reactor, 10 ... Output current sensor , 11 ... battery current sensor, 12 ... discharge voltage detector, 20 ... battery, 21 ... additional battery, 31 ... AC input power supply, 32 ... load, 50 ... comparator, 51 ... discharge end voltage converter, 52 ... discharge time Counter, 53 ... Charging time counter,
54a ... full charge time setter, 54b ... comparator, 54c ... plus limiter, 54d ... constant, 54e ... adder, 54 ... charge / discharge time converter, 55 ... discharge end voltage setter, 56 ... discharge end voltage adjuster 57 ... Discharge power integrator, 58 ... Discharge end energy setting device, 61 ... Discharge time, 62 ... Charge time, 63 ... Discharge time, 500 ... Control circuit, 501 ... Input voltage detection circuit, 502 ... Comparator, 503 ... Power failure detection level setting device, 504... Crystal transmitter, 505.

Claims (1)

When AC input power is normal, AC power is supplied to the load and the battery is charged via a power converter that converts AC power to DC power and DC power to AC power. In an uninterruptible power supply having a battery charging / discharging circuit that enables the supply of the discharge power of the battery to the load via the power converter,
A discharge voltage detecting means for detecting a discharge voltage of the battery;
Charging time measuring means for measuring the charging time of the battery;
A discharge time measuring means for measuring the discharge time of the battery;
The discharge end voltage can be converted with respect to the discharge time of the battery, and by inputting the net discharge time, the discharge end voltage converting means for outputting the discharge end voltage with respect to the net discharge time, and
Input the measured charging time that is the output of the charging time measuring means and the measured discharging time that is the output of the discharging time measuring means, and subtract the measured charging time from the time required for full charging to calculate the time required for full charging. The time is converted into the discharge time, and the measured discharge time is added to obtain the net discharge time. The net discharge time is equivalent to the time when the battery is discharged from the fully charged state. A charge / discharge time converter for inputting as a net discharge time of the discharge end voltage conversion means,
The discharge end voltage, which is the output of the discharge end voltage conversion means, is compared with the detected discharge voltage detected by the discharge voltage detection means. Comparing means for outputting a discharge stop command for
An uninterruptible power supply characterized by comprising:

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