JP2728682B2 - Uninterruptible power supply for computer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an uninterruptible power supply for a computer.

[Conventional technology]

For example, in a circuit for converting a DC voltage of an uninterruptible power supply into a high-frequency AC voltage as described in IEEJ Vol. Determined by frequency.

Conventionally, this commutation circuit has been configured by using R in combination with a load resistor.

[Problems to be solved by the invention]

In the above-mentioned prior art, R of R of CRL constituting a commutation circuit is used.
In addition, no consideration is given to the fact that R varies with load fluctuations, and the problem that the commutation period, that is, the frequency of the high-frequency output and the output voltage value, vary with load fluctuations. Atsuta.

Further, the output voltage value has a problem that the fluctuation of the input power source appears as it is in addition to the above-described load fluctuation.

The present invention has been made in view of the above points, and provides an uninterruptible power supply device for a computer that enables a frequency and a voltage value of a high-frequency voltage output to be constant even when a load and a power supply fluctuate. It is intended to provide.

[Means for solving the problem]

That is, the present invention provides an uninterruptible power supply for a computer that converts a commercial power supply into a direct current and further converts it into a high-frequency alternating current. And a converter that converts a DC current of the battery into an AC current and supplies the AC current to a load, and a commutation circuit that constitutes the converter,
An AC inverter, a timing controller for giving a firing command to a gate of a DC / AC inverter, an AC output voltage detector for detecting a load supply voltage, and an AC output voltage control device for controlling an AC output voltage are provided independently of the battery power line. The commutation circuit is connected to a series connection circuit of a thyristor, a reactor, and a capacitor coupled to both terminals of the battery, and a first circuit provided in parallel with the capacitor and operated by an instruction of the timing controller.
A series-connected body of a commutation transistor and a resistor, and a second commutation transistor provided in parallel with the reactor and operated according to an instruction of the timing controller, and an AC output side of the DC / AC inverter. The saturable reactor and the load whose inductance is changed by a control DC current value output from an AC output voltage control device based on a detection value of the AC output voltage detector,
It is designed to achieve the initial purpose without connecting in series.

Further, in this case, the capacitor of the commutation circuit is connected to the DC voltage of the battery by a resonance operation with the reactor.
It is formed so that an ON signal is given to the base of the second commutation transistor at the time of being charged to the double voltage.

[Action]

That is, with the power supply device thus formed, the constant of the commutation circuit does not fluctuate even when the load and the power supply fluctuate, and the saturable reactor increases and decreases even when the output voltage fluctuates. The frequency of the AC output and the shared voltage of the load become constant regardless of the magnitude of the load, and the frequency and voltage value of the high-frequency voltage output can be kept constant even when the load and the power supply fluctuate. It is.

〔Example〕

Hereinafter, the present invention will be described based on the illustrated embodiments.
1 to 4 show one embodiment of the present invention. In the present embodiment, in a power supply device with an uninterruptible power supply for a computer, which converts a commercial power supply, that is, a three-phase AC power supply 1 into a DC and further converts it into a high-frequency AC, in this embodiment, the apparatus is constituted by rectifying the three-phase AC power supply 1 And a converter 5 that converts the DC current of the battery 2 into an AC current and supplies the AC current to the load 4, and a commutation circuit 5 a, which constitutes the converter 5. Of the DC / AC inverter 5b, the timing controller 17, the AC output voltage detector 22, and the output voltage control device 23, the commutation circuit 5a is provided on a power supply line independently of the DC / AC inverter 5b, and the DC / AC inverter 5b
In addition, a saturable reactor 6 whose inductance changes according to the DC current value is provided in series with the load 4. By doing so, the constant of the rectifier circuit 5a does not fluctuate even if the load 4 and the power supply 1 fluctuate, and even if the output voltage fluctuates, the saturable reactor 6 can be increased or decreased to cope with it. Accordingly, the frequency of the AC output and the shared voltage of the load 4 are constant irrespective of the magnitude of the load 4, and the frequency and voltage value of the high-frequency voltage output are constant even when the load 4 and the power supply 1 fluctuate. Thus, it is possible to obtain an uninterruptible power supply device for a computer which enables the above.

That is, as shown in FIG. 1, the AC current output from the AC power supply 1 is rectified by the AC / DC converters (rectifiers) 3a and AVR 3b of the rectifier 3 and converted into a DC current. To store. The rectified DC current is converted into an AC current by the converter 5 and supplied to the load 4. When a power failure occurs and the output of the AC power supply 1 is lost, the DC current stored in the battery 2 is sent to the conversion unit 5 to be converted into an AC current, and is supplied to the load 4. Current can be supplied to the load 4 even during a power failure.

Next, the detailed configuration of each block will be described. The rectifier 3 includes a rectifier 3a composed of a diode and an SCR, and a battery 2
AVR 3b that measures the terminal voltage of battery 2 to determine the state of charge of battery 2 and controls the SCR of rectifier 3a to keep the terminal voltage of battery 2 constant.

The battery 2 needs to have enough capacity to supply current to the load 4 until a power failure occurs, until the voltage is restored again, or until an auxiliary power supply such as a diesel engine generator enters a steady operation state. Become.

The converter 5 operates three sets of similar circuits with a phase shift of 120 ° to generate a three-phase alternating current. The operation is the same, so only one set of converters 5 will be described. The configuration has an insulating transformer 7 for AC output, and SCRs 8, 9, 10, 11 for switching for passing AC current to the transformer 7.
DC / AC inverter 5b and SCR12, reactor 13, capacitor 14, transistor for commutating these SCRs 8-11
A commutation circuit 5a having 15, 16 and a timing controller 17 for turning on the SCRs 8 to 11 and commutation transistors 15, 16 at an appropriate timing, and a DC / AC inverter 5b
From the flywheel diodes 18, 19, 20, 21; the AC output voltage detector 22; and the output voltage control device 23 for controlling the AC output voltage to be constant by passing a DC current through the saturable reactor 6 according to the AC output voltage. Be composed.

The operation of the converter 5 will be described with reference to the timing chart of FIG. First, when the timing controller 17 supplies a turn-on signal to the gate terminals of the SCRs 12, 8, and 11, a current flows through battery 2, SCR 12, SCR 8, saturable reactor 6, AC output insulating transformer 7, SCR 11, battery 2. The current waveform at this time is a sinusoidal waveform shown in the primary current (i) of the current output insulating transformer 7 in the timing chart of FIG. 2 due to the inductive load. When the SCRs 12, 8 and 11 are turned on, a current flows from battery 2 → SCR 12 → reactor 13 → capacitor 14 → battery 2 and the reactor 14
13, By the LC series resonance of the capacitor 14, a voltage at most twice the battery voltage is stored. Timing controller when the terminal voltage of the capacitor 14 becomes maximum
When the transistor 15 is turned on by 17, a reverse bias corresponding to the battery voltage is applied to the SCR 12, so that the SCR 12 is turned off. However, in order to turn off the SCR12, it is necessary to apply a reverse bias for more than the time (turn-off time) specified by the element,
15 needs to keep ON state for more than turn-off time. SCR1
When the transistor 15 is turned off after the transistor 2 is completely turned off, the current flowing through the saturable reactor 6, the AC output insulating transformer 7 flows through the flywheel diode 20 → battery 2 → flywheel diode 19, and Regenerated in

With the above, SCR8,11 turned off, then SCR12,1
0, 9 are turned on, and a current in the opposite direction to that described above is supplied to the AC output insulating transformer 7, but before the accumulated charge of the capacitor 14 is completely discharged, the reactor 13, the capacitor Since the case where the boost charging of the capacitor 14 is not performed due to the LC series resonance of 14 occurs, the transistor 16 is turned on immediately after the transistor 15 is turned off, and the accumulated charge of the capacitor 14 is discharged through the resistor 13a. After the transistor 16 is turned off and the SCRs 12, 10, and 9 are turned on, the operation is the same as that after the SCRs 12, 8, and 11 are turned on. Flows, and an AC voltage is generated on the secondary side of the AC output insulating transformer 7. The half cycle of this AC voltage is half the resonance cycle determined by L of the reactor 13 and C of the capacitor 14, that is, And transistor 15 determined by the turn-off time of SCR12
The ON time of the transistor 16 and the ON time of the transistor 16 determined from the time required for discharging the accumulated charge of the capacitor 14 are determined by the sum of the three. Therefore, the values of the reactor 13 and the capacitor 14 are determined by calculating backward from the required AC output frequency. Since there is no item depending on the load current in the parameters of the cycle calculation of the AC voltage, the frequency of the AC output is constant regardless of the size of the load 4.

Further, when the load 4 fluctuates, the loss due to the SCR, the transformer and the like changes, and the AC output voltage fluctuates. So the third
Feedback control is performed on the AC output voltage by the output voltage control device 23 shown in the figure to keep the output constant. The feedback control operation will be described below with reference to FIG.

The AC output voltage is peak-held by the AC output voltage detector 22 and output to the output voltage control device 23. The output voltage control device 23 compares the peak hold value of the input AC output voltage with the reference voltage value, and
And the DC current on the control winding side of the saturable reactor 6 inserted in the series.

The saturable reactor 6 has an inductance value on the vertical axis and a DC current value on the horizontal axis, as shown in FIG. 4 where the relationship between the DC current value and the inductance value is shown. The inductance value decreases as the side current value increases. As described above, the saturable reactor 6 has a characteristic that the inductance changes when the DC current is changed. Therefore, when the AC output voltage is equal to or lower than the reference, the DC current flowing to the saturable reactor 6 is increased, and the inductance is reduced. By doing so, the voltage applied to the AC output insulating transformer 7 is increased. When the AC output voltage is equal to or higher than the reference value, the reverse control is performed.

As described above, according to the present embodiment, the following effects can be obtained.

(1) The frequency of the AC output can be kept constant regardless of the magnitude of the load.

(2) Since the frequency of the AC output can be kept constant regardless of the magnitude of the load, the ripple fluctuation accompanying the load fluctuation when the AC output is rectified and used is small.

(3) Since feedback control can be performed on the output voltage, voltage fluctuations due to load fluctuations are small.

In other words, even if the load and the power supply fluctuate, the frequency and voltage value of the output voltage can be kept constant, and commutation does not fail, and a stable power supply can be performed. Containers and ripple filters can be miniaturized.

〔The invention's effect〕

As described above, according to the present invention, the frequency and voltage value of the high-frequency voltage output are constant even when the load and the power supply fluctuate,
It is possible to obtain an uninterruptible power supply device for a computer that can keep the frequency and the voltage value of the high-frequency voltage output constant even when the load and the power supply fluctuate.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of an uninterruptible power supply for a computer according to the present invention, FIG. 2 is an operation time chart of the same embodiment, and FIG. 3 is an output voltage control device of the same embodiment. FIG. 4 is a characteristic diagram showing the relationship between the DC side current value and the inductance value of the saturable reactor of one embodiment. 1 ... AC power supply (commercial power supply), 2 ... Battery, 3 ...
… Rectifier, 3a …… AC / DC converter (rectifier), 3b …… A
VR, 4 load, 5 conversion unit, 5a commutation circuit, 5b
... DC / AC inverter, 6 ... Saturable reactor, 12 ... S
CR, 13 ... Reactor, 13a ... Resistance, 14 ... Capacitor, 15,16 ... Commutation transistor, 17 ... Timing controller, 22 ... AC output voltage detector, 23 ... Output voltage control device.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masato Ito 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubu Plant of Hitachi, Ltd. (56) References JP-A-57-145581 (JP, A) JP-A-58-127564 (JP, A) JP-A-54-115752 (JP, A) JP-B-47-15492 (JP, B1)

Claims (2)

(57) [Claims] 1. An uninterruptible power supply for a computer for converting a commercial power supply into a direct current and further converting it into a high-frequency alternating current. And a converter for converting a DC current of the battery into an AC current and supplying the AC current to a load, and a commutation circuit, a DC / AC inverter, and a D that constitute the converter.
A timing controller for giving a firing command to a gate of a C / AC inverter, an AC output voltage detector for detecting a load supply voltage, and an AC output voltage controller for controlling an AC output voltage are independently connected to the battery power line. A first commutation transistor provided in parallel with the capacitor, and a series connection circuit of a thyristor, a reactor, and a capacitor coupled to both terminals of the battery; And a series connection of a resistor and a second commutation transistor provided in parallel with the reactor and operated according to an instruction of the timing controller, and the AC output side of the DC / AC inverter, Control DC current output from the AC output voltage controller based on the value detected by the voltage detector Its inductance and changes saturable reactor the load and, computing dexterity uninterruptible with power supply, characterized in that so as to serially connect the. 2. An ON signal is applied to the base of the second commutation transistor when the capacitor of the commutation circuit is charged to a voltage twice as high as the DC voltage of the battery by a resonance action with the reactor. The uninterruptible power supply for a computer according to claim 1, wherein the power supply is provided so as to provide the following.