JPH051962Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is an uninterruptible power supply that combines a switching regulator that operates at high frequency and a storage battery, and more specifically, a field-effect transistor that uses a field-effect transistor as a switching element. Regarding uninterruptible power supplies that supply power to the load in parallel with the storage battery while floatingly charging the storage battery using the switching power supply used, it is particularly important to prevent failures such as overcurrent destruction of field effect transistors when power is restored after an input power outage. Concerning the means to do so.

(Prior Art) The following configuration has been proposed as an uninterruptible power supply device that combines a switching regulator that operates at high frequency and a storage battery. That is,
Turns on the field effect transistor and the same switching element as a switching element to the input power supply,
A chopper control circuit for off-control is connected, and while the storage battery is floatingly charged by the output voltage of the chopper circuit consisting of the switching element, reactor, diode, and smoothing capacitor, a load (for example, a converter transistor) is connected in parallel with the storage battery. It supplies electricity to the

(Problem to be Solved by the Invention) By the way, in the above-mentioned uninterruptible power supply, the field effect transistor usually has a built-in diode that protects the transistor against high voltage surges generated in the reactor. Even during a power outage, auxiliary power continues to be supplied from the storage battery to the chopper control circuit via the reactor, the field effect transistor, and the like. Then,
The chopper control circuit continues to operate even during a power outage, and the pulse width of the pulse that controls the field effect transistors to turn on and off according to the discharge (voltage drop) of the storage battery voltage is operated so that the on time is maximized. When the power is restored in this state, the output voltage of the field effect transistor becomes higher than the voltage of the storage battery, and a large charging current flows due to the difference between the two voltages.
Failures such as destruction of the transistor due to excessive current occur.

This invention solves the above problems and restores power in an uninterruptible power supply that supplies power to a load in parallel with a storage battery while floatingly charging the storage battery with a switching power supply having a switching element made of a field effect transistor. It is an object of the present invention to provide a means for preventing failures such as overcurrent destruction of field effect transistors during electric power.

(Means for Solving the Problems) In order to achieve the above object, this invention provides an uninterruptible power supply having the above configuration, which includes a control circuit that controls on/off switching elements, and a control circuit that controls the power supply of this control circuit. The control circuit includes means for supplying from the input side of the switching element and a voltage identification circuit that identifies the input power supply voltage and the storage battery voltage, and the control circuit performs its control operation in the event of a power outage according to the detected voltage of the voltage identification circuit. The switching device is configured to stop the power supply, and when the power is restored, the on-time of the switching element is gradually increased from the minimum time.

(Function) Based on the above configuration, the on/off control operation of the control circuit is stopped in the event of a power outage according to the detected voltage of the voltage identification circuit, and the on time of the switching element is changed from the minimum time when the power is restored. It gradually increases in size and shifts to steady operation.

(Example) An example of the uninterruptible power supply of this invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of this invention in which the input is an AC power supply.
b. The voltage discrimination circuit 31 comprising a resistor 31c and the connection for supplying the voltage generated across the resistor 31c in the voltage discrimination circuit 31 to the chopper control circuit 17 embody the main features of this invention.

In FIG. 1, 11 is an AC power source as an input power source (main power source), and its voltage is usually
It is 100V or 200V. 12a is a switch that opens and closes the AC input, and 12b is a switch that supplies voltage from a storage battery 21 (described later) to the converter control circuit 23. Both switches are mechanically interlocked, and when the former is closed, the latter is also closed. When the switch 12a is closed, the input power from the AC power supply 11 is rectified by a rectifier 13 made of a diode, smoothed by a capacitor 14, and a DC voltage corresponding to the voltage of the AC power supply 11 is generated at the capacitor 14. transistor 1
5 has a resistor 15a and a zener diode 15 connected in series between the output terminals of the rectifier 13.
The base voltage is equal to the voltage of the zener diode 15b, and a voltage corresponding to that voltage is generated at the emitter. This emitter voltage is supplied to the chopper control circuit 17, and serves as its auxiliary power source. Become.

Reference numeral 16 denotes a field effect transistor constituting a switching element, which is controlled to be turned on or off by a chopper control circuit 17. The chopper control circuit 17 has the function of generating pulses for on/off control, the field effect transistor 16, and the reactor 1.
8. It has an automatic voltage control function that performs constant voltage control so that the output voltage of the chopper circuit (voltage generated at the smoothing capacitor 20) made up of the diode 19 and the smoothing capacitor 20 becomes the floating charging voltage of the storage battery 21. . When the AC power supply 11 is supplied, the above-mentioned chopper circuit floatingly charges the storage battery 21 and supplies power to the transistor switching circuit 22 in the converter circuit as a load.

The converter circuit consists of a transistor switching circuit 22, an isolation transformer 25, a diode rectifier 26, a reactor 27, and a smoothing capacitor 28. The converter circuit converts direct current into alternating current by turning on and off the transistor switching circuit 22, and converts direct current into alternating current. After the voltage is converted by 25, it is rectified by a rectifier 26, and converted to direct current by a reactor 27 and a smoothing capacitor 28, thereby supplying constant voltage power to a load 30.
23 is a converter control circuit which turns on the transistor in the transistor switching circuit 22;
Function to generate off-control pulses and load 30
controlling the pulse width of the above-mentioned pulse according to the detection signal of the voltage detection circuit 29 that detects the voltage applied to the
It has an automatic control function that controls the voltage of the load 30 to be constant by changing the on/off interval. The voltage of the storage battery 21 is supplied to the converter control circuit 23 via the switch 12b, and serves as an auxiliary power source for driving the circuit 23. Note that the voltage identification circuit 31 will be described later.

In the above configuration, even if the AC power supply 11 fails, the converter circuits 22 to 28 continue to operate with the power from the storage battery 21, so that the apparatus shown in FIG. 1 constitutes an uninterruptible power supply.

Furthermore, as shown in FIG. 2, the field-effect transistor 16 usually has a built-in diode 16a with the polarity shown in the figure, so that when the input power supply 11 has a power outage, as described above, The output of the rectifier 13 drops to zero, but the output of the storage battery 2
1 to reactor 18, field effect transistor 1
6 internal diode 16a and transistor 15
Auxiliary power continues to be supplied to the chopper control circuit 17 via. Therefore, the chopper control circuit 1
7 continues the operating state, and the pulse width for controlling the field effect transistor 16 on and off according to the discharge (voltage drop) of the storage battery voltage is operated so that the on time is maximized. In this state, when the AC power supply 11 is restored, the output voltage of the field effect transistor 16 becomes higher than the voltage of the storage battery 21, and a large charging current flows due to the difference between the two voltages.
6 may cause problems such as destruction due to excessive current.

To prevent the above-mentioned failure from occurring, power supply 1
The starting means may be such that the operation of the chopper control circuit 17 is stopped at the time of the first power outage, and when the power is restored, the ON time of the field effect transistor 16 as a switching element is gradually increased from the minimum. The voltage identification circuit 31 in FIG. 1 embodies the above-mentioned starting means and has a function of identifying the input voltage from the power source 11 and the voltage of the storage battery 21. That is, the voltage identification circuit 31 includes a resistor 31a and a zener diode 31 connected between the output terminals of the rectifier 13.
It consists of a series circuit consisting of a resistor 31c and a resistor 31c.
The voltage of c is used as the control voltage in the chopper control circuit 17.
is applied to

The chopper control circuit 17 stops the on/off control operation when the control voltage is below a certain value, and when the control voltage is above a certain value, the circuit 17 generates on/off control. The on-time of the pulse is configured to gradually increase from the minimum. For example, if the zener voltage of the zener diode 31b is set higher than the voltage of the storage battery 21, no voltage is generated across the resistor 31c during a power outage, and the chopper control circuit 17 maintains a stopped state. On the other hand, when the power is restored, the output voltage of the rectifier 13 (which is higher than the voltage of the storage battery 21) is generated, and if this voltage is set higher than the zener voltage of the zener diode 31b, then when the power is restored, As a result, a voltage is generated across the resistor 31c, and the chopper control circuit 17 gradually increases the on-time of the generated pulse from the minimum.
Shift to steady operation.

The voltage identification circuit 31 is a zener diode 31b.
It is also possible to configure a series circuit consisting of only a resistor 31c and a resistor 31c, but if a resistor 31a is further connected in series as shown in FIG. This configuration is actually possible because the voltage can be applied.
Further, in FIG. 1, the input power source 11 is an AC power source, and the load of the storage battery 21 is the switching circuit 22, but the former may be a DC power source, and the latter may be another load. Further, the configuration of each circuit in FIG. 1 can be changed as appropriate according to known means.

(Effects of the invention) As described above, according to this invention, a voltage identification circuit is provided to distinguish between the voltage of the input power source and the voltage of the storage battery that is floatingly charged by the present power supply device, and the power source is determined according to the detected voltage. When stopped, the operation of the control circuit that controls switching elements on and off is stopped,
Since the ON time of the switching element is made to gradually increase from the minimum time when the power is restored, it is possible to prevent problems such as overcurrent destruction of the field effect transistor when the power is restored.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the uninterruptible power supply of this invention.
FIG. 2 is a detailed circuit diagram of the field effect transistor in FIG. 1.

Claims (1)

[Claims for Utility Model Registration] The above-mentioned switching power supply is achieved by inserting a switching element made of a field effect transistor having a parasitic diode between the source and drain in the electric path between the output end of a rectifier that rectifies the AC power supply and the storage battery. An uninterruptible power supply device that supplies power to a load in parallel with the storage battery while floatingly charging the storage battery, comprising: a control circuit that controls on/off of the switching element; and a control circuit that supplies power to the control circuit from the input side of the switching element. means for supplying power and allowing current to flow from the storage battery to the input side of the element via the parasitic diode when the AC power supply fails; and means provided between the output terminal of the rectifier, A voltage identification circuit that identifies the voltage and the voltage of the storage battery, and the control circuit stops the control operation in the event of a power outage, and switches the switching element to An uninterruptible power supply that is configured to gradually increase the on time of the unit from a minimum time.