JPH09322433A - Ups built-in power supply equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to immediately correspond to a trouble or power interruption at one of the power supplies by the other and to improve the efficiency by supplying DC power to a load in parallel at a predetermined ratio from both the UPS power supply section for supplying DC to the load from the main power section and battery for converting commercial power supply to DC power. SOLUTION: DC power created by a commercial power supply by a main power supply section 2 is supplied to a load 5 and a battery 32 is charged by DC power created from the commercial power supply by the main power supply section 2 and by a UPS(uninterruptive power supply) power supply section 3, and the predetermined DC power is created based on this DC power or DC power from the battery 32 and is supplied to the load 5. At this time, the control is performed so as to supply DC power to the load 5 from other when a balance control section 4 is no more necessary to detect the proportion of DC power supplied from both the sections to the load 5 and to control it to a predetermined value or when DC power is no more supplied from the main power supply section 2 or UPS power supply section 3. At this time, the balance control section 4 is set to the constant voltage control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a UPS built-in power supply device for supplying DC power from a commercial power supply to a load.

[0002]

2. Description of the Related Art Conventionally, an uninterruptible power supply (referred to as UPS)
As shown in FIG. 7, the power supply device having a built-in power supply device includes power converters (here, an AC-DC converter and a DC-DC converter).
Converters) are connected in series. During a constant period, DC power is supplied from a commercial power source (AC 100V) to the load via the AC-DC converter and the DC-DC converter.

Further, as shown in FIG. 8, when the UPS is externally attached to a processing device having a load, the UPS is provided with a bypass route for directly supplying commercial power to the processing device when the power converter fails. However, in a system in which a failure of the power converter is immediately detected and reliability is improved, power is always supplied to the load from the route on the power converter side. Therefore, in a system with high reliability (a system that constantly monitors and detects a failure of the power converter), power is always supplied to the load from the route on the power converter side, and the power converter in the processing device having the load ( here,
AC power is generated and supplied by the AC-DC converter.

[0004]

The above-described conventional method of FIG. 7 is simple in control and structure and is often used, but since the number of stages passing through the power converter (two in the example of FIG. 7) is large. Especially, when a large DC current is supplied to the load, there is a problem that the conversion efficiency of power consumption is poor and power is wasted. In the example of FIG. 7, the number of stages passing through the power converter is 2. Therefore, if the power conversion efficiency of each power converter is 80%, 0.80 × 0.80 = 0.64.
Then, the power conversion efficiency of 64% had deteriorated.

In the above-mentioned conventional UPS externally-enhanced system with improved reliability, a three-stage power converter is passed before the commercial power source supplies the actual load, and particularly a large DC current is loaded. When the power is supplied to the power source, the conversion efficiency of the power consumption is poor and the power is wasted. In the example of FIG. 8, since the number of stages passing through the power converter is three, if the power conversion efficiency of each power converter is 80%, 0.80 × 0.80 × 0.80 = 0.51.2
Then, the power conversion efficiency was 51.2%.

As described above, conventionally, the efficiency of a device equipped with a UPS is significantly lower than the efficiency of a device without a UPS when a DC power supply is supplied to a load from an AC power supply by an AC-DC converter. There was a problem that caused it.

[0007] The present invention solves these problems,
DC power is supplied to the load in parallel at a predetermined ratio from both the main power supply that converts commercial power to DC power and the UPS power supply that supplies DC power to the load from the battery, improving efficiency and failure or power failure of either one. Sometimes the other aims to supply immediately and increase reliability.

[0008]

Means for solving the problem will be described with reference to FIG. In FIG. 1, the processing device 1 is composed of a main power supply unit 2, a UPS power supply unit 3, a balance control unit 4, a load 5, and the like, and performs various processes according to a program.

The main power source unit 2 is a commercial power source (here, AC1
00V) to supply DC power to the load 5.
The UPS power supply unit 3 charges the battery 32 from a commercial power supply, generates DC power, and supplies the DC power to the load 5.

The balance control unit 4 includes a main power supply unit 2 and U
The ratio of the current supplied from the PS power supply unit 3 to the load 5 is controlled. Next, the operation will be described.

The main power supply unit 2 supplies the DC power generated from the commercial power supply to the load 5, and the UPS power supply unit 3 charges the battery 32 with the DC power generated from the commercial power supply, and the DC power or the DC power from the battery 32 is charged. Based on the above, a predetermined DC power is generated and supplied to the load, and at this time, the balance control unit 4 detects the ratio of the DC power supplied to the load 5 and controls the balance so as to maintain it at a predetermined value. When the DC power is no longer supplied from the main power supply unit 2 or the UPS power supply unit 3 to the load 5, control is performed so that the DC power is supplied to the load 5 from other sources.

At this time, the balance control section 4 controls the voltage supplied to the load 5 at a constant voltage. Further, the balance control unit 4 determines a failure when the ratio of the currents supplied to the load 5 by the main power supply unit 2 or the UPS power supply unit 3 is out of a predetermined range, and notifies the CPU or the like of that by an interrupt. I have to.

Further, the balance control unit 4 is provided with a circuit for setting the current ratio supplied from the outside to the load from the main power supply unit 2 or the UPS power supply unit 3 to an arbitrary value. Therefore, the main power supply unit 2 for converting the commercial power supply into DC power and the UPS power supply unit 3 for supplying DC power from the battery to the load
By supplying DC power from both of the above in parallel to the load at a predetermined ratio, the efficiency can be improved and the other can be immediately supplied in the event of a failure or power failure of one of them to improve reliability.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment and operation of the present invention will be sequentially described in detail with reference to FIGS.

FIG. 1 is a block diagram showing an embodiment of the present invention.
In FIG. 1, a processing device 1 performs various kinds of processing according to a program, and here, a main power supply unit 2, UP
The S power supply unit 3, the balance control unit 4, the load 5, and the like are included.

The main power source section 2 is a commercial power source (here, AC1).
00V) to supply DC power to the load 5 and is, for example, an AC-DC converter. This main power supply unit 2 generates a power supply + 5VDC of 100V AC and supplies it to a load (IC or the like).

The UPS power supply unit 3 has a battery 32 when a power failure occurs.
The DC power of a predetermined voltage is generated on the basis of the DC power from the DC power supply and is supplied to the load 5. Here, it is configured by a battery charging converter 32, a DC-DC converter 33, and the like.

The battery charging converter 32 is a DC power supply for charging the battery 32 from a commercial power source and a DC-D.
The DC power for supplying a part of the load power to the load 5 via the C converter 33 is generated.

The battery 32 is for floating-charging and supplying to the load 5 the DC power generated by the DC-DC converter 33 when a power failure occurs. The DC-DC converter 33 uses a DC voltage (for example, 30V) of the battery 32.
DC) to DC voltage (+ 5VDC) of load 5
It is something to convert.

In the balance control section 4, the main power source section 2 is a load 5
The DC power supplied to the load 5 and the DC power supplied to the load 5 by the UPS power supply unit 3 are controlled to a predetermined value. Here, when the ratio of the two can be controlled to a predetermined value, it is controlled to a predetermined value. On the other hand, when the ratio cannot be controlled to a predetermined value, it is considered that a failure has occurred in either the main power supply unit 2 or the UPS power supply unit 3, Load all DC power from the person who can supply normally 5
Or control to supply to. At this time, constant voltage control is performed so that a constant DC voltage is always supplied to the load 5.

Next, changes in the state of the configuration of FIG. 1 will be described in detail with reference to (1) to (4) of FIG. FIG.
Shows an example of an operation pattern of the present invention.

FIG. 2A shows a steady state. In this steady state, the balance control unit 4 supplies the DC power generated by the main power supply unit 2 from the commercial power supply to the load 5 as illustrated.
The DC power generated by the UPS power supply unit 3 from the commercial power supply is supplied to the load 5 by 10%. At this time, the battery 32 is floatingly charged by the DC power generated from the commercial power source and is always kept fully charged.

As described above, by supplying 90% to the load 5 from the main power supply unit 2 which is a one-stage power converter, and 10% to the load 5 from the UPS power supply unit 3 which is a two-stage power converter, both are constantly supplied. It is possible to check whether the operation is normal by supplying from the power source and to obtain the overall efficiency as shown in the following calculation formula, which is 78.4%, which is 80% of the efficiency of the one-stage power converter of the main power supply unit 3. The values are almost equal to each other, which is a significant improvement over the conventional value of 0.80 × 0.80 = 0.64 = 64% in the example of FIG.

(0.9 × 0.8 + 0.1 × 0.8 × 0.
8) ÷ (0.9 + 0.1) = 0.784 = 78.4% Incidentally, in order to simplify the explanation, the efficiency of each power converter is set to 80%.

FIG. 2B shows a power failure state. In this power failure state, as shown in the figure, the entire DC power is generated from the battery 32 and supplied to the load 5. At this time, in the transition from the state (1) in FIG. 2 to the state (2) in FIG. 2, since the power supply from the main power supply unit 2 became 0% due to the power failure, the UPS power supply unit 3 automatically made up the shortage. As a result, 100% is supplied as a result.

FIG. 2 (3) shows a state where the remaining battery level is low. In this state where the remaining amount of the battery is low, a battery remaining amount detection circuit (not shown) operates and detects that the remaining amount of the battery 2 is low. Therefore, an interrupt is sent to the CPU of the processing device 1 (not shown). The processing device 1 side saves data and completes preparations for stopping the supply of DC power after a predetermined time.

FIG. 2 (4) shows the battery check state. In order to check the capacity decrease due to the life of the battery 32 in the state of (1) of FIG.
U prompts discharge of the battery 32 and gives a battery check instruction. At this time, as shown in the figure, the balance control unit 4 supplies a DC current of, for example, 10% from the main power supply unit 2 to the load 5
To the load 5 to control, for example, the remaining 90% DC power from the UPS power supply unit 3 to the load 5, and the time until the battery remaining amount decrease signal is output from the battery remaining amount detection circuit (not shown). Is measured, the battery life is determined to be shorter than a predetermined time, the CPU is notified of that by an interrupt, and the steady state of (1) in FIG. 2 is restored. On this occasion,
The charging of the battery 32 is stopped by the battery charging converter 31, or a load current larger than the capacity of the battery charging converter 31 is supplied to the load 5 to check the capacity of the battery 32.

FIG. 3 is a circuit diagram of the present invention. This is a specific circuit configuration diagram of FIG. 1 described above. The configuration and the operation thereof will be sequentially described in detail below with reference to FIGS. Here, the main power supply unit 2, the UPS power supply unit 3, and the balance control unit 4 in the figure correspond to the corresponding numbers in FIG. 1, respectively.

In FIG. 3, the main power source section 2 is composed of 21 to 27, R1 and L1 as shown in the figure, and rectifies AC100V to generate a DC voltage and transforms it to a predetermined value. The DC power is supplied to the load 5 at a ratio.

The rectifier circuit 21 rectifies both waves of AC100V to generate a DC voltage. Capacitor C22
Is for charging a DC voltage that has been double-wave rectified by the rectifier circuit 21 to form a smooth DC voltage.

The DC-DC converter 23 choppers a DC voltage with a predetermined pulse width to generate a predetermined AC voltage. At this time, the pulse width is a PWM wave and has a voltage output waveform as shown in (a) of FIG. 4 described later, and is controlled by the balance control unit 4 so as to have a desired output current or a desired output voltage. It is what is done.

The rectifiers 24 and 25 are for rectifying the AC voltage generated by the DC-DC converter 23 into a DC voltage. The resistor R1 is a resistor for detecting the current supplied to the load 5.

The coil L1 is for smoothing the direct current supplied to the load 5. The amplifier 26 amplifies the voltage (voltage proportional to the current supplied to the load 5) generated across the resistor R1.

The averaging circuit 27 averages the signals amplified by the amplifier 26. This averaged signal is supplied to the amplifier (division) 4 of the balance control unit 4 described later.
It is input as the dividend signal of 6.

Under the configuration of the main power supply unit 2 as described above, the DC power is supplied from the AC 100 V to the load 5 at a predetermined current ratio under the control of the balance control unit 4 (as shown in FIG. 2 described above, (DC power is supplied to the load 5 at a predetermined rate in the normal state, DC power supply is stopped in the power failure state, and DC power is supplied to the load 5 at a rate of 100% when the UPS power supply unit 3 fails) I am trying to do it.

The UPS power supply unit 3 has three components as shown in the figure.
1 ', 32 to 36, R2, L2, etc., which rectify AC100V to charge the battery 32, or transform the rectified DC voltage to supply the DC voltage to the load 5 at a predetermined ratio. It is something to do.

The charging circuit 31 'is a circuit (AC-DC converter) that rectifies 100V AC to generate a DC voltage of a predetermined voltage. The battery 32 stores DC power.

The DC-DC converter 33 choppers a DC voltage with a predetermined pulse width to generate a predetermined AC voltage. At this time, the pulse width is a PWM wave and has a voltage output waveform as shown in FIG. 4B, which will be described later, and is controlled by the balance control unit 4 so as to have a desired output current or a desired output voltage. It is what is done.

The rectifier 34 is a DC-DC converter 33.
The AC voltage generated by is rectified into a DC voltage. The resistor R2 is a resistor for detecting the current supplied to the load 5.

The coil L2 is for smoothing the DC current supplied to the load 5. The amplifier 35 amplifies the voltage (voltage proportional to the current supplied to the load 5) generated across the resistor R2.

The averaging circuit 36 averages the signals amplified by the amplifier 35. This averaged signal is supplied to the amplifier (division) 4 of the balance control unit 4 described later.
Input as a divisor signal of 6.

Under the above-described structure of the UPS power supply unit 3, DC power is supplied from the AC 100 V to the load 5 at a predetermined current ratio under the control of the balance control unit 4 (as shown in FIG. 2 described above, In the normal state, DC power is supplied to the load 5 and the battery 32 is floatingly charged at a predetermined small ratio, in the power failure state, the DC power is supplied, and when the main power supply unit 2 fails, the DC power is supplied at a ratio of 100%. Supply to load 5)
I am trying to do it.

The balance control unit 4 includes the main power source unit 2 and U
The current and voltage supplied from the PS power supply unit 3 to the load 5 are detected, and the pulse width of the PWM wave for controlling the DC-DC converter 23 of the main power supply unit 2 is controlled based on the detected current and voltage, and The pulse width of the PWM wave that controls the DC-DC converter 33 of the UPS power supply unit 3 is controlled,
The DC power is supplied to the load 5 at a predetermined ratio, and is composed of 41 to 52 and the like.

The OSC 41 is an oscillator and is a signal for controlling the pulse width of the DC-DC converter 23 of the main power supply unit 2 and the DC-DC converter 33 of the UPS power supply unit 3. The DC-DC converter 23 of the main power supply unit 2
Pulse width signal to be supplied to the UPS and the DC-D of the UPS power supply unit 3.
The pulse width signal supplied to the C converter 33 has a phase of 1
The signal is inverted and controlled by the inverter 43 so as to be different by 80 °.

The comparison circuit 42 compares the signal from the OSC 41 with the signal for controlling the DC power supplied to the load 5 of the main power supply section 2, generates a PWM wave and supplies it to the DC-DC converter 23. (See (a) of FIG. 4).

The comparator circuit 44 compares the signal obtained by inverting the signal from the OSC 41 by the inverter 43 with the signal for controlling the DC power supplied to the load 5 of the UPS power supply unit 3, and P
The WM wave is generated and supplied to the DC-DC converter 33 (see (b) of FIG. 4).

The amplifier 45 supplies the voltage supplied to the load 5 to R
Compared with EF1 (reference voltage 1), signal b which is an error voltage
(Signal b for constant voltage feedback) is detected. The amplifier 46 divides the signal X from the averaging circuit 27 of the main power supply unit 2 by the signal Y from the averaging circuit 36 of the UPS power supply unit 3 (X ÷ Y) to calculate the ratio. .

The comparison circuit 47 compares a default value or a ratio (balance value) set from the outside with the current ratio from the amplifier 46, and outputs the error signal a. The amplifier 48 outputs the sum of the signal a and the signal b, inputs the sum to the above-mentioned comparison circuit 42, and supplies the DC power corresponding to the sum from the main power supply unit 2 to the load 5.

The amplifier 49 outputs the difference between the signal "a" and the signal "b" and inputs it to the above-mentioned comparison circuit 44 to input it to the UPS power supply unit 3
To supply DC power corresponding to the difference to the load 5.

The amplifier 50 compares with a default value or a ratio (balance value) set from the outside, and inputs the error signal a to the comparison circuits 51 and 52. The comparison circuits 51 and 52 compare the reference values REF2 and REF3 with the error signal a, output a signal when the difference is out of the range defined by REF2 and REF3, and output a balance abnormality signal to the outside. It is a thing.

Under the configuration of the balance control section 4 described above,
The current and voltage supplied from the main power supply unit 2 and the UPS power supply unit 3 to the load 5 are detected, and based on these signals, negative feedback is used to supply the specified ratio of DC power to the load 5 or during a power failure. When the main power supply unit 2 fails, 100% DC power is supplied from the UPS power supply unit 3 to the load 5, or the main power supply unit 2
Also, when the ratio of the DC power supplied to the load 5 by the UPS power supply unit 3 is out of the specified range, a balance abnormality signal is notified to a CPU (not shown) by interruption. The operation will be sequentially described in detail below with reference to FIGS.

Although not shown in FIG. 3, the constant voltage control is prioritized over the constant current ratio control to stabilize the circuit. FIG. 4 shows an explanatory diagram of current adjustment by PWM according to the present invention.

FIG. 4A shows the waveform of the main power supply section 2. (A-1) of FIG. 4 is an OSC waveform and shows the waveform of the OSC 41 of FIG. Here, a triangular wave is generated.

FIG. 4A-2 shows a current output waveform, which is the current output waveform of the DC-DC converter 23 shown in FIG. In this, in (a-1), the OSC waveform is compared with the threshold value, and when the threshold value is exceeded, switching is turned on and a direct current is supplied to the load 5.

In FIGS. 4A-1 and 4A-2, the left side shows (1) the waveform when the load current is large,
The right side shows (2) the waveform when the load current is small. When the load current is large, the pulse width becomes wide as shown on the left side of (a-2), and as a result, a large direct current is supplied to the load 5. Conversely, if the load current is small,
As shown on the right side of (a-2), the pulse width is narrowed, and as a result, a small DC current is supplied to the load 5.

FIG. 4B shows the waveform of the UPS power supply section 3. FIG. 4B-1 shows an OSC waveform, which is shown in FIG.
The waveform of the OSC41 of FIG. here,
The waveform is inverted so that the switching ONs of the main power supply unit 2 and the UPS power supply unit 3 do not overlap with each other and the operation is performed stably.

FIG. 4B-2 shows a current output waveform, which is the current output waveform of the DC-DC converter 33 shown in FIG. In these (b-1) and (b-2) of FIG.
The left side shows the waveform when (1) the load current is large, and the right side shows the waveform when (2) the load current is small. When the load current is large, the pulse width becomes wide as shown on the left side of (b-2), and as a result, a large direct current is supplied to the load 5. Conversely, when the load current is small, (b-
As shown on the right side of 2), the pulse width is narrowed, and as a result, a small direct current is supplied to the load 5.

FIG. 5 is an explanatory diagram showing the relationship between the current ratio control and the PWM according to the present invention. (1) of FIG. 5 shows the PW of the main power supply unit 2.
The M characteristic is shown. As shown, PWMDuTy (PWM pulse width duty) changes from 0 to 100% corresponding to the PWM threshold voltage.

FIG. 5B shows the PWM of the UPS power supply unit 3.
Show the characteristics. Similarly, as illustrated, PWMDuTy (PWM pulse width duty) changes from 0 to 100% corresponding to the PWM threshold voltage.

FIG. 5C shows the state when the load current is small. At this time, as indicated by the dotted line, the main power supply unit 2 of (1) and the UPS of (2) are corresponding to a small load current.
The PWM pulse width duty of the power supply unit 3 is controlled to be small. Here, each signal of a, b, c, d is a signal of a portion described on the circuit of FIG. 3, and is the following signal described on the right side of the drawing.

A: current balance value feedback voltage value b: constant voltage feedback voltage value c: main power supply PWM threshold voltage d: UPS power supply PWM threshold voltage In FIG. 5 (4), the load current is large. The situation at the time of is shown. At this time, as indicated by the dotted line, the P of the main power supply unit 2 of (1) and the P of the UPS power supply unit 3 of (2) correspond to the large load current.
The pulse width duty of WM is largely controlled.

FIG. 5 (5) shows the battery check. In this case, as indicated by the dotted line, (1) the PWM pulse width duty of the main power source unit 2 is controlled to be small, and (2) the PWM pulse width duty of the UPS power source unit 3 is controlled to be large, so that the battery When the time until the voltage drop is detected is smaller than the specified value, it is determined that the battery life has deteriorated and the battery life has expired. Then, the original ratio (the ratio of the current of the main power supply unit 2 is large, the current of the UPS power supply unit 3 is (The ratio is small), and the battery check sequence ends.

FIG. 5 (6) shows a state when the main power supply unit fails or a power failure occurs. In this case, as shown by the dotted line,
Only the pulse width duty of the UPS power supply unit 3 of (2) is controlled.

FIG. 5 (7) shows a state when the UPS power supply unit fails. In this case, as shown by the dotted line, only the pulse width duty of the main power supply unit 2 in (1) is controlled. FIG.
Shows an explanatory diagram of current transition during a power failure.

FIG. 6A shows the current transition of the main power supply section, and FIG. 6B shows the current transition of the UPS power supply section. Here, the vertical axis represents the output current and the horizontal axis represents the time. When a power failure occurs, the main power supply 2
While the DC power charged in the capacitor is supplied for a while, the ratio of the DC power supplied from the UPS power supply unit 3 to the load 5 rises (is kept constant).

At the point of "power supply output stop" in the figure, as the supply of DC power from the capacitor of the main power supply unit 2 to the load 5 is stopped, DC power from the battery of the UPS power supply unit 3 is supplied. Will be done.

As described above, the ratio of the DC power supplied to the load 5 from the main power supply unit 2 to the UPS power supply unit 3 gradually increases due to the DC power charged in the capacitor of the main power supply unit 2 at the time of power failure. The current can be smoothly transferred without interruption.

[0068]

As described above, according to the present invention,
Since the main power supply unit 2 for converting the commercial power supply into DC power and the UPS power supply unit 3 for supplying DC power from the battery to the load are supplied in parallel at a predetermined ratio,
The efficiency can be improved, and when one of the main power supply unit 2 and the UPS power supply unit 3 fails or has a power failure, the other can immediately and smoothly supply DC power to enhance reliability. With these features, not only the DC power supply at the time of power failure, but also when the main power supply unit 2 or the UPS power supply unit 3 fails, the DC power can always be stably supplied to the load and the system down can be avoided. In spite of this, it has become possible to realize a power supply device that has the same power conversion efficiency as when using only a single power supply and that meets the energy environmental standards.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an example of an operation pattern of the present invention.

FIG. 3 is a circuit configuration diagram of the present invention.

FIG. 4 is an explanatory diagram of current adjustment by PWM according to the present invention.

FIG. 5 is an explanatory diagram of a relationship between current ratio control and PWM according to the present invention.

FIG. 6 is an explanatory diagram of current transition during a power failure of the present invention.

FIG. 7 is a block diagram of a conventional UPS (built-in UPS).

FIG. 8 is a block diagram of a conventional UPS (external UPS).

[Explanation of symbols]

 1: Processing device 2: Main power supply 3: UPS power supply unit 31: Battery charging converter 32: Battery 33: DC-DC converter 4: Balance control unit 5: Load

Claims (5)

[Claims] 1. A U for supplying DC power from a commercial power source to a load.
In the PS built-in power supply device, a main power supply unit that converts commercial power to DC power and supplies the load, a battery that is charged by the DC power converted from the commercial power supply or a part of the DC power from the main power supply unit, A UPS power supply unit that converts the DC power charging the battery or the DC power converted from the DC power of the battery into the DC power for the load, and supplies the load from the main power supply unit and the UPS power supply unit, respectively. The ratio of the DC power to be controlled to a predetermined value, or a circuit for controlling the DC power from one of them to be supplied to the load from the other when the supply of the DC power is stopped. Power supply with built-in UPS. 2. The UPS built-in power supply device according to claim 1, further comprising a circuit for controlling a constant voltage of a voltage supplied to a load during the control. 3. The method according to claim 1, wherein when the main power supply unit or the UPS power supply unit goes out of a predetermined range with respect to a ratio of currents supplied to a load, it is determined that a failure has occurred and the fact is output. Item 3. The UPS built-in power supply device according to Item 2. 4. The circuit according to claim 1, further comprising a circuit for externally setting a current ratio supplied to the load from the main power supply unit or the UPS power supply unit to an arbitrary value. UPS built-in power supply. 5. The UPS built-in power supply device according to claim 1, wherein the constant voltage control is prioritized over the constant current ratio control.