JP3675009B2 - AC power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in the reliability of an AC power supply device having a storage battery in a DC circuit.
[0002]
[Prior art]
Prior art will be described with reference to the drawings.
[0003]
FIG. 2 is a block diagram showing a configuration of a conventional AC power supply device. In this figure, 1 is an input terminal, 2 is a rectifier, 3 is an inverter, 4 is an output terminal, 11 is a capacitor, and 12 is a storage battery.
[0004]
The input terminal 1 is for inputting AC power to the AC power supply apparatus, and the output terminal 4 is for outputting AC power from the AC power supply apparatus. In general, a commercial power supply system is connected to the input terminal 1 and a load is connected to the output terminal 4. The rectifier 2 inputs AC power and outputs DC power, and the inverter 3 inputs DC power and outputs AC power. The AC input side of the rectifier 2 is connected to the input terminal 1, the DC output side is connected to the DC input side of the inverter 3, and the AC output side of the inverter 3 is connected to the output terminal 4. Further, both the capacitor 11 and the storage battery 12 are connected in parallel to the DC input side of the inverter 3.
[0005]
The operation of the AC power supply device is as follows. When the commercial power supply system connected to the input terminal 1 is healthy, the rectifier 2 operates by receiving AC power from the commercial power supply system, supplies DC power to the inverter 3 and charges the storage battery 12. The inverter 3 converts the DC power supplied from the rectifier 2 into AC power optimum for the load, and supplies the AC power to the load via the output terminal 4. When the storage battery 12 is already fully charged, the rectifier 2 performs a minute charge to compensate for the self-discharge of the storage battery 12.
[0006]
When the commercial power system fails, the rectifier 2 becomes inoperable and stops. Instead, the storage battery 12 discharges and supplies DC power to the inverter 3. In general, since the storage battery 12 starts discharging immediately when the rectifier 2 stops, the inverter 3 can continuously supply AC power to the load without instantaneous interruption. When the commercial power supply system recovers, the rectifier 2 resumes operation and supplies DC power to the inverter 3 and recovers and charges the storage battery 12.
[0007]
In general, a static inverter using a semiconductor element is used as the inverter 3, and the semiconductor element performs a switching operation at a high speed to convert DC power into AC power. At that time, a ripple current having a magnitude proportional to the output current of the inverter 3 flows to the DC input side of the inverter 3. The capacitor 11 is provided as a main supply source of this ripple current. Since the ripple current is shunted between the capacitor 11 and the storage battery 12, the storage battery 12 also functions as a supply source of the ripple current.
[0008]
As is well known, the actual capacity of a storage battery gradually decreases due to aging, and eventually reaches the end of its life and becomes unusable. In the AC power supply device of FIG. 2, if the actual capacity of the storage battery 12 decreases due to aging, there is a case where power cannot be supplied to the load during a power failure of the commercial power supply system. Therefore, in order to ensure the reliability of the device, it is important to periodically grasp the deterioration state of the storage battery 12 and replace it with a new one if it deteriorates.
[0009]
Various methods have been proposed as a method for grasping the deterioration state of the storage battery. One of the effective methods is a method of measuring the internal resistance or the internal impedance of the storage battery. Generally, a deteriorated storage battery has a large internal resistance and internal impedance. Thus, several devices for measuring the internal impedance of the storage battery have been proposed. As a method for measuring the internal impedance of a storage battery, a method in which the storage battery is charged or discharged with a predetermined current, a voltage increase or a voltage drop of the storage battery at that time is measured, and divided by an energization current is widely used.
[0010]
FIG. 3 is a block diagram showing the configuration of an AC power supply apparatus equipped with a discharge type storage battery internal impedance measuring apparatus. In this figure, 100 is a storage battery internal impedance measuring device, 101 is a simulated load for discharging the storage battery, 102 is a voltage measuring means for measuring the storage battery voltage, 103 is a switch for opening and closing the storage battery circuit, 104 is a diode for bypassing, Reference numeral 105 denotes arithmetic control means. The storage battery internal impedance measuring apparatus 100 includes a simulated load 101, a voltage measuring unit 102, a switch 103, a diode 104, and an arithmetic control unit 105. Since other configurations are the same as those in FIG.
[0011]
The simulated load 101 and the voltage measuring means 102 are connected to the storage battery 12 in parallel, and the switch 103 is connected to the storage battery 12 in series. The diode 104 is connected to the switch 103 in parallel, and its direction is non-conductive with respect to the charging current of the storage battery 12 but is conductive with respect to the discharging current. The arithmetic control means 105 controls the operation of the simulated load 101, the voltage measuring means 102, and the switch 103, and performs necessary arithmetic processing. The storage battery 12 is connected in series with the switch 103 and then connected in parallel to the DC input side of the inverter 3.
[0012]
The operation of the storage battery internal impedance measuring apparatus 100 is as follows. When measuring the internal impedance of the storage battery 12, the switch 103 is opened to disconnect the storage battery 12 from the rectifier 2, the simulated load 101 is operated to discharge the storage battery 12, and the voltage drop of the storage battery 12 at that time is measured by the voltage measuring means 102. Measure with By dividing the measured voltage drop by the discharge current at the simulated load 101, the internal impedance of the storage battery 12 is obtained. On the other hand, when the internal impedance of the storage battery 12 is not measured, the switch 103 is closed and the storage battery 12 is connected to the rectifier 2. The above operation is controlled by the arithmetic control means 105.
[0013]
Here, when measuring the internal impedance of the storage battery 12, the switch 103 is opened to disconnect the storage battery 12 from the rectifier 2 in order to prevent current from flowing from the rectifier 2 to the simulated load 101. The reason why the diode 104 is provided is to ensure the discharge from the storage battery 12 even if the commercial power supply system fails when the switch 103 is open.
[0014]
[Problems to be solved by the invention]
In the above-described conventional technology, the storage battery internal impedance measuring device 100 is provided to measure the internal impedance of the storage battery 12, so that the configuration of the AC power supply device becomes complicated and disadvantageous in terms of dimensions, weight, price, and the like. there were. Further, if the switch 103 fails, the storage battery 12 may not be charged, and there is a problem in terms of reliability.
[0015]
The objective of this invention is providing the alternating current power supply device which enabled it to grasp | ascertain the degradation condition of a storage battery by simple structure by measuring the ripple voltage and ripple current of a storage battery.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a ripple voltage measuring means for measuring a ripple voltage superimposed on a storage battery, a ripple current measuring means for measuring a ripple current flowing in the storage battery, and a ripple of the storage battery measured by the ripple voltage measuring means. An internal impedance deriving unit for deriving the internal impedance of the storage battery by gradually calculating the voltage value from the ripple current value of the storage battery measured by the ripple current measuring unit is provided.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
In the AC power supply apparatus according to the present invention, the ripple voltage measuring means measures the ripple voltage superimposed on the storage battery, and the ripple current measuring means measures the ripple current flowing through the storage battery. The measured ripple voltage value and ripple current value of the storage battery are taken into the internal impedance deriving unit, and the internal impedance deriving unit divides the ripple voltage value by the ripple current value to derive the internal impedance of the storage battery.
[0018]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a block diagram showing the configuration of an AC power supply apparatus embodying the present invention. In this figure, 13 is a ripple voltage measuring means for measuring a ripple voltage superimposed on the storage battery 12, 14 is a ripple current measuring means for measuring a ripple current flowing through the storage battery 12, and 15 is a state of the storage battery 12 measured by the ripple voltage measuring means 13. The internal impedance deriving unit derives the internal impedance of the storage battery 12 by gradually calculating the ripple voltage value from the ripple current value of the storage battery 12 measured by the ripple current measuring unit 14. Since other configurations are the same as those in FIG.
[0020]
The ripple voltage measuring means 13 is connected in parallel to the storage battery 12 for the purpose of measuring the ripple voltage superimposed on the storage battery 12, and the ripple current measuring means 14 is connected in series to the storage battery 12 for the purpose of measuring the ripple current flowing through the storage battery 12. The The ripple voltage value of the storage battery 12 measured by the ripple voltage measurement unit 13 and the ripple current value of the storage battery 12 measured by the ripple current measurement unit 14 are taken into the internal impedance deriving unit 15. The internal impedance deriving means 15 divides the ripple voltage value by the ripple current value to derive the internal impedance of the storage battery 12.
[0021]
In the AC power supply device, the capacitor 11 and the storage battery 12 supply the ripple current of the inverter 3. In other words, the ripple current generated by the inverter 3 on the DC input side is shunted to the capacitor 11 and the storage battery 12. Therefore, each ripple voltage represented by the product of each internal impedance and each ripple current is superimposed on the capacitor 11 and the storage battery 12. Therefore, if the ripple voltage value and the ripple current value of the storage battery 12 are measured and the ripple voltage value is divided by the ripple current value, the internal impedance of the storage battery 12 can be derived. As described above, since the internal impedance of a storage battery generally increases when it deteriorates with age, if the internal impedance of the storage battery 12 is derived by this method, the deterioration state can be grasped.
[0022]
【The invention's effect】
According to the present invention, by measuring the ripple voltage and ripple current of the storage battery, it becomes possible to grasp the deterioration status of the storage battery with a simple configuration, so the dimensions, weight, price, reliability, etc. of the AC power supply device Can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the configuration of an AC power supply device embodying the present invention. FIG. 2 is a block diagram showing the configuration of a conventional AC power supply device. FIG. Block diagram showing device configuration 【Explanation of symbols】
DESCRIPTION OF SYMBOLS 1 Input terminal 2 Rectifier 3 Inverter 4 Output terminal 11 Capacitor 12 Storage battery 13 Ripple voltage measurement means 14 Ripple current measurement means 15 Internal impedance derivation means

Claims (1)

In an AC power supply apparatus comprising an inverter that inputs DC power and outputs AC power, and a storage battery connected in parallel to the DC input side of the inverter,
Ripple voltage measuring means for measuring a ripple voltage superimposed on the storage battery;
Ripple current measuring means for measuring a ripple current flowing in the storage battery;
An internal impedance deriving unit for deriving an internal impedance of the storage battery by gradually calculating a ripple voltage value of the storage battery measured by the ripple voltage measuring unit by a ripple current value of the storage battery measured by the ripple current measuring unit; An AC power supply apparatus comprising:

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