JPH11275778A - Power supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device for feeding power to a DC voltage with a waveform that does not obstruct the breaking characteristics of a breaker or the like, even if power is fed to a load facility using a breaker for breaking an AC current. SOLUTION: A power supply device constantly closes a switch S1, opens a switch S2, and feeds power from a commercial AC power supply CS to a load computer 10 and then opens the switch S1 and closes the switch S2 at power failure, closes semiconductor switches Q1 and Q4, and feeds power to the load computer 10 with a voltage E1 of a battery B1. The semiconductor switches Q1 and Q4 are opened periodically and the switches Q2 and Q3 are closed, and a voltage E1 with a negative polarity is applied to the load computer 10, while the semiconductor switches Q2 and Q3 are turned on. Even if an arc discharge occurs when the computer 10 is short-circuited or the like, the arc discharge is extinguished by reversing the polarity of voltage periodically.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device that supplies power with a DC voltage and a power supply device that always supplies power with an AC voltage and supplies a DC voltage when a power failure occurs.

[0002]

2. Description of the Related Art The most common power supply device receives commercial AC power at all times, converts it into a DC voltage once by a rectifier, and converts the DC voltage into a high-precision frequency and sine wave voltage again by an inverter. Convert and supply power. In addition, at the time of a power failure of a commercial power supply, a method is employed in which the discharged power of the battery is converted into an AC voltage by the inverter and fed. In the operation state in the normal power supply, the power loss of the rectifier and the inverter is large, so that the efficiency of the device is as low as about 80%.
Power supplies also need to be much more efficient to meet international environmental issues, such as strengthening energy conservation efforts, or to respond to resource conservation needs.

As a method of improving power supply efficiency at all times, there is a method in which power is directly supplied from a commercial power supply to a load, that is, power is supplied without operating a rectifier or an inverter with loss, and the inverter is operated only when a power failure occurs to supply power. . This method has found practical use in small capacity devices.

Further, as a method of increasing the efficiency even when power is supplied from a battery at the time of a power failure, conversion into a sine-wave AC voltage by an inverter (the loss of a semiconductor switch is large because the waveform is controlled by using the high-frequency switching technology of the inverter) is increased. There is also disclosed a method of supplying power with a DC voltage without a process. When a load is used by converting AC power received like a computer into DC, it is used as a circuit that does not interfere with operation even if it is supplied with DC voltage from the outside. −33
233 AC / DC power supply).

FIG. 10 is a diagram showing a circuit configuration of AC / DC power supply in a conventional power supply device. A switch is switched to supply power to a computer as a load with an AC voltage from a commercial AC power supply or a DC voltage from a battery. The rectifier circuit on the load side does not matter whether the input voltage is AC or DC. What is needed is the level of the voltage to be supplied. The DC voltage is selected between the average value of the AC voltage and the peak value. This level can be obtained by selecting the number of batteries connected in series or increasing or decreasing the output voltage of the battery by a chopper circuit.

[0006]

Although this method is excellent from the viewpoint of energy saving, it has a drawback associated with DC power supply. If the load side is a facility for receiving an AC voltage, for example, a computer, there may be a case where the breaking characteristic of the breaker for cutting off the receiving current may be inconvenient. When the current is interrupted by a breaker, an arc is generated. However, in the case of AC power, the polarity of the voltage is periodically inverted. In the case of 50 Hz, the polarity is inverted every 20 milliseconds. Disappears. However, in the case of DC current, the arc once generated is difficult to extinguish because there is no mechanism for reversing the current polarity. The higher the DC voltage, the harder the arc is extinguished, and in some cases, the arc cannot be cut off, which is dangerous.

[0007] If the AC breaker used on the load equipment side is replaced with a large-sized and expensive DC cut-off, the arc can be cut off and the problem can be solved, but power is supplied to an unspecified large number of loads. In the case of a general-purpose power supply device, a measure cooperating with the load side cannot be taken. In other words, it is not possible to force the load side to replace the breaker with a DC breaker.

The present invention has been made in view of the above-described circumstances, and a DC voltage having a waveform that does not hinder the cutoff characteristics of a breaker or the like even when power is supplied to a load facility using a breaker for alternating current cutoff. An object is to provide a power supply device that can supply power.

[0009]

In order to easily extinguish the arc discharge of the breaker, the DC voltage to be supplied is not set to a continuous wave, but is provided with a period in which it is periodically zero, or is negative, that is, inverted. The DC voltage waveform has a period in which the polarity is provided. In other words, a condition similar to the AC current cutoff is created for the breaker.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve the above problems, a power supply device of the present invention is a power supply device that supplies power with a DC voltage and a power supply device that always supplies power with an AC voltage and supplies a DC voltage when a power failure occurs. This DC voltage is characterized in that it has a waveform in which a period of zero voltage or a period of negative polarity is provided periodically. Further, the present invention is characterized in that the period during which the DC voltage has zero or negative polarity is in the range of 0.5 to 5 milliseconds. Further, the present invention is characterized in that the DC voltages having different polarities are obtained by conversion with a chopper. Also, the invention is characterized in that the DC voltage having a negative polarity is obtained by a series resonance circuit of a reactor and a capacitor.

[0011]

FIG. 1 shows a first embodiment of the present invention. (A)
Is a circuit configuration diagram, and (b) is a waveform of an output DC voltage during a power failure, that is, a period during which power is supplied from the battery. S1
And S2 are switches, which may use relays, breakers or semiconductor switches. Normally, the switch S1 is closed and S2 is opened to supply power to the load computer 10 from the commercial AC power supply CS. In the event of a power failure, switch S1 is opened and S2 is closed, and semiconductor switches Q1, Q
4 is closed and the load computer 1 is driven by the voltage E1 of the battery B1.
Power 0. The semiconductor switches Q1 and Q4 are opened periodically and Q2 and Q3 are closed. While the semiconductor switches Q2 and Q3 are on, a negative voltage E1 is applied to the load computer 10.

FIG. 2B shows a waveform of the DC power supply voltage generated by the interruption of the semiconductor switches Q1 to Q4 at the time of power failure. Even if an arc discharge occurs in the breaker CB on the load side, for example, when a short circuit fault occurs in the computer 10, the arc is extinguished by periodically changing the polarity of the voltage. A commercial frequency AC current interrupting breaker is used in an AC circuit in which a polarity change occurs every half cycle, ie, every 10 milliseconds (at 50 Hz). Therefore, even when used in a DC circuit, it is not necessary to make the polarity switching period (ton) shorter than 10 milliseconds. The limit that can extend the cycle is the voltage to cut off,
Depends on current and circuit conditions. The time during which the negative voltage is applied (toff) is determined by the time required until the polarity of the power supply current is reversed. If the load can be regarded as a resistance, the load is reversed instantaneously. However, if the inductance of the power supply cable or a noise suppression filter is present, the time until the current is reversed is later than the time of the voltage reversal. It does not require more than ２ ， of the half-cycle of the AC voltage, that is, 5 ms or more. Therefore, the period during which the polarity of the DC voltage is inverted to the negative polarity may be selected as large as 5 milliseconds in view of safety.

The diodes D1 to D4 connected in antiparallel with the respective semiconductor switches Q1 to Q4 are connected to the semiconductor switches Q1 to Q4.
ＱQ4 is inserted in order to prevent a reverse voltage from being applied and destroyed. If the reverse breakdown voltage of the semiconductor switch is high, it is not necessary to provide a diode.

FIG. 2 is a circuit diagram of an AC / DC power supply according to a second embodiment of the present invention. In the first embodiment (FIG. 1), the level when the DC voltage is positive is equal to the level when the DC voltage is at the negative polarity, and is the voltage E1. However, the voltage level during the negative polarity is not directly related to the amount of power to be supplied, and can be arbitrarily selected. In the second embodiment, the level of the voltage E2 during the negative polarity period is selected to be lower than the voltage E1 of the batteries B2 and B3 connected in series. Voltage E2
Is a battery B obtained by dividing the batteries B2 and B3 connected in series.
3 is the battery voltage.

FIG. 3 is a circuit diagram of an AC / DC power supply according to a third embodiment of the present invention. When two sets of batteries B1 and B3 are used, the semiconductor switch Q5 is turned on to supply power at the voltage E1 of the battery B1 when DC voltage is supplied. When periodically applying a negative voltage, the semiconductor switch Q5 is turned off,
Q6 is turned on to output the voltage -E2 of the battery B3.

FIG. 4 is a circuit diagram of an AC / DC power supply according to a fourth embodiment of the present invention. 13 is a circuit configuration example in a case where a DC voltage applied to a load is periodically dropped to zero in a fourth embodiment. DC voltage pattern in the first embodiment (FIG. 1b)
In this example, the polarity of the DC voltage is periodically inverted. However, for example, it is not always necessary to make the polarity of the DC voltage negative if the power supply cable is short and the inductance when the load is viewed from the power supply is small. By reducing the DC voltage to zero or near zero, the supply current can be reduced to a level at which the breaker can shut off. That is, the breaking function expected from the breaker can be performed.

In the example, the circuit configuration is the same as that of the third embodiment (FIG. 3) except for the battery B3, the semiconductor switch Q6, and the diode D6. When the semiconductor switch Q5 is turned on, power is supplied at the voltage E1, and when the Q5 is periodically turned off, the power supply voltage becomes zero.

FIG. 5 shows a first example of a DC power supply unit applied to the power supply device of the present invention. The semiconductor switch Q7, the diode D7, the reactor L, and the capacitor C1 constitute a boost chopper, and boosts the voltage E2 of the battery B4, for example, DC48V, to a desired voltage E1, for example, DC140V. That is, when the semiconductor switch Q7 is turned on, the discharge current of the battery B4 flows through the reactor L, and the electromagnetic energy becomes 1/2
× (inductance) × (current) ² is accumulated. During this time, the voltage E1 of the capacitor C1 becomes the output voltage. Next, when Q7 is turned off, the current of the reactor L becomes the diode D7.
Through the capacitor C1. The reactor L emits energy by inducing a voltage having the polarity shown in the figure according to the law of conservation of energy. The voltage E1 is the sum of the voltage of the battery B4 and the voltage of the reactor L, and has a level increased by the voltage of the reactor L. The ON / OFF cycle of the semiconductor switch Q7 is repeatedly operated to control the voltage E1 to a desired level. The switching frequency is increased to, for example, 20 kHz or more in order to reduce the inductance of the reactor L to reduce the size and cost. A control signal for turning on / off the semiconductor switch Q7 is provided from a control device not shown.

The DC power supply of the first embodiment is used in place of the battery B1 of the first embodiment (FIG. 1). Also, battery B4
And the boosted voltage E1 are used in place of the batteries B2 and B3 in the second embodiment (FIG. 2).

FIG. 6 shows a second example of a DC power supply unit applied to the power supply device of the present invention. DC power supply unit of the first example (FIG. 5)
The reactor LX, the capacitor C2 and the diode D8
Is a circuit to which is added. Reactor LX is magnetically coupled to reactor L. During the period when the voltage having the polarity shown is induced in the reactor L, the voltage having the polarity shown is also induced in the reactor LX, so that the capacitor C2 is charged. The + E1,0, -E2 of the DC power supply unit of the second example is used by replacing the batteries B1 and B3 of the third embodiment (FIG. 3).

FIG. 7 shows a DC power supply unit of a third example applied to the power supply device of the present invention. In the DC power supply unit (FIG. 5) of the first example, the voltage of the battery B4 and the voltage of the reactor L are superimposed to make the voltage of the capacitor C1, that is, + E1 of the output. On the other hand, in the DC power supply unit of the third example, the capacitor C3 is charged with the voltage induced in the reactor L, and the voltage of the battery B4 and the voltage of the capacitor C3 are added to obtain an output voltage + E1. This output voltage + E1 is used instead of the battery B1 of the first embodiment (FIG. 1). In addition, voltages + E1 and + E2
Is used in place of the batteries B2 and B3 of the second embodiment (FIG. 2).

FIG. 8 shows a fourth example of a DC power supply unit applied to the power supply device of the present invention. This is an example in which the way of extracting the output is changed using the DC power supply unit (FIG. 7) of the third example. Capacitor C
3 is + E1 and the battery B4 is -E2. This DC power supply can be replaced by the batteries B1 and B3 of the third embodiment (FIG. 3).

Since a single battery has a low voltage, a large number of batteries are connected in series and used. This battery has large voltage fluctuations. In the case of a lead-acid battery, the voltage directly obtained from the battery is
2.22V to 1.6V in the process from charge to discharge
Fluctuate up to If the DC power supply unit of the first to third embodiments (FIGS. 1 to 3) is replaced by a battery and a DC power supply unit composed of a chopper of FIGS. 5 to 8 is used, the voltage to be supplied is maintained at a constant level. Desirable for

FIG. 9 is a circuit diagram of an AC / DC power supply according to a fifth embodiment of the present invention. The pulse voltage obtained by the series resonance of the reactor and the capacitor is used as the negative voltage during the DC voltage supply. A state in which power is supplied from a battery during a power failure will be described. DC voltage is supplied from the battery B1 by turning on the semiconductor switch Q8. Periodically, Q8 is turned off to provide the load computer 10 with a negative pulse resulting from the next process. When the thyristor TH is turned on because the capacitor C4 is charged with the polarity shown in the figure, the reactors L2 and L3 (L2 and L3 may be independent components, or may be magnetically coupled components) and the capacitor C4. Initiate series resonance.

The voltage of the capacitor C4 decreases, and then the voltage increases in the opposite polarity to that shown in the figure. The sum (negative polarity) of the voltage of the opposite polarity of the capacitor C4 and the voltage of the reactor L3 is applied to the computer 10. Is done. Then, a reverse resonance current starts flowing through the diode D10, and the capacitor C4 returns to the illustrated polarity again. At this time, the thyristor TH is not supplied with a signal for conducting, so that the series resonance does not continue. After this process, the semiconductor switch Q8 is turned on to supply DC power at the level of the voltage E1.

Instead of the battery B1 in the fifth embodiment (FIG. 9), a DC power supply constituted by the chopper shown in FIGS. 5 and 7 can be used.

The reactor L3 is inserted to suppress the charging current of the capacitor C4 flowing at the moment when the semiconductor switch Q8 is turned on, and is not always necessary unless the charging current becomes excessive. A triac or a transistor can be used instead of the thyristor TH.

The polarity reversal of the DC voltage applied to the load is performed periodically. There is no problem if the polarity inversion cycle is a half cycle of a commercial AC power supply, that is, about 10 milliseconds. However, if a chopper is used in the power supply, for example, as shown in FIGS. Abnormal increase does not occur, and the polarity inversion cycle may be extended up to about 1 second.

In the illustration of the present invention, a bipolar transistor is taken as an example of a semiconductor switch. However, the present invention is not limited to this, and power MOSFETs and IGBTs can be used without any problem. In addition, a lead storage battery, a solar battery, a fuel cell, and the like are also practically used as batteries. In principle, electric double layer capacitors, which are not batteries but are expected to be put to practical use, can also be used.

When a solar cell or a fuel cell is used as a battery, there is no need to rely on a commercial AC power supply. If there is a rectifier that converts AC power to DC, it may be used at all times. In these cases, the load is always supplied with DC voltage except for the circuit of the AC power supply system (the system having the changeover switch S) from the first to fourth embodiments.

[0031]

According to the present invention, the zero voltage is periodically set during the supply of the DC voltage, or the polarity of the voltage is set to be negative.
For example, even if an arc discharge occurs on the load side due to a short circuit accident or the like, the arc discharge does not continue for a period longer than this cycle. Therefore, even if the breaker provided on the power supply path has a small AC current interrupting capability, that is, a small interrupting capability, there is no practical problem, and DC power can be supplied to electronic equipment such as a computer designed for AC power receiving. As a result, the efficiency of the power supply device is improved, which can greatly contribute to the promotion of energy saving.

[Brief description of the drawings]

FIG. 1A is a circuit configuration diagram of AC / DC power supply in a first embodiment, and FIG. 1B is an output waveform diagram of a DC voltage.

FIG. 2 is a circuit configuration diagram of AC / DC power supply in a second embodiment.

FIG. 3 is a circuit configuration diagram of AC / DC power supply in a third embodiment.

FIG. 4 is a circuit configuration diagram of AC / DC power supply in a fourth embodiment.

FIG. 5 is a circuit configuration diagram of a DC power supply unit of a first example applied to the power supply device of the present invention.

FIG. 6 is a circuit configuration diagram of a DC power supply unit of a second example applied to the power supply device of the present invention.

FIG. 7 is a circuit configuration diagram of a DC power supply unit of a third example applied to the power supply device of the present invention.

FIG. 8 is a circuit configuration diagram of a DC power supply unit of a fourth example applied to the power supply device of the present invention.

FIG. 9 is a circuit configuration diagram of AC / DC power supply in a fifth embodiment.

FIG. 10 is a circuit configuration diagram of AC / DC power supply in a conventional power supply device.

[Explanation of symbols]

 10 Computer as load B1,2,3,4 Battery C1,2,3,4 Capacitor CB breaker CS Commercial AC power supply D1,2,3,4,5,6,7,8,9 Diode E1, Voltage L, L2, 3 reactor LX reactor Q1, 2, 3, 4, 5, 6, 7, 8 semiconductor switch S1, switch TH thyristor

Claims (4)

[Claims] 1. A power supply device that supplies power with a DC voltage and a power supply device that always supplies power with an AC voltage and supplies a DC voltage when a power failure occurs, wherein the DC voltage periodically has a period of zero voltage or a negative polarity. A power supply device having a waveform provided with a certain period. 2. The power supply device according to claim 1, wherein a period during which the DC voltage has zero or negative polarity is in a range of 0.5 to 5 milliseconds. 3. The power supply device according to claim 1, wherein said DC voltages having different polarities are obtained by conversion by a chopper. 4. The power supply device according to claim 1, wherein the DC voltage having a negative polarity is obtained by a series resonance circuit of a reactor and a capacitor.