JPH08256482A - Uninterruptible power unit, and its insulation method and its power supply method - Google Patents

Abstract

PURPOSE: To lessen loss and enable downsizing without giving interference noise to other electronic devices by constituting an insulating circuit of a capacitor. CONSTITUTION: An insulating circuit 45 is one where primary terminals A and B and secondary terminals C and D are connected with each other through capacitors C1 and C2 each in series, and an insulating barrier 44 is constituted between the primary terminals A and B and the secondary terminals C and D by the capacitors C1 and C2, and the secondary terminals C and D electrically float to the primary terminals A and B. And, the current outputted from a high-frequency switching power circuit 15 is transmitted to the other side through the dielectrics inside the capacitors C1 and C2, with electric fields as media, without flowing directly inside the capacitors C1 and C2. As a result, it hardly give rise to iron loss or copper loss, so the reduction of loss is possible, and since it does not need a high-frequency transformer, the downsizing of the insulating circuit becomes possible.

Description

Description: TECHNICAL FIELD The present invention relates to an uninterruptible power supply device, an insulation method for the same, and a power supply method for the same, and more specifically, a frequency for exchanging electric power from a power supply with high-frequency electric power. The present invention relates to an uninterruptible power supply that employs a conversion circuit, its insulation method, and its power feeding method.

[Prior Art] The basic function of the uninterruptible power supply is to supply power to the load even if the commercial power supply on the input side fails. The commercial power source is used as an energy source at all times, and the stored energy stored in a storage battery is used as an energy source during a power failure to supply power to the load.

 Usually, in an uninterruptible power supply, a transformer for insulation is used for its output part in its output part.

However, since this transformer is for low frequencies, it is inevitably a certain size and weight in principle, which is a major obstacle to downsizing and weight saving of the uninterruptible power supply.

 Recently, except for this low-frequency transformer, a high-frequency switching power supply circuit that outputs high-frequency AC power is often used, and insulation is often used in this part. That is, an insulating circuit composed of a high frequency transformer is used on the output stage side of a high frequency switching power supply circuit that outputs high frequency AC power. This type of uninterruptible power supply has recently been put to practical use, and is generally called a high-frequency intermediate link type uninterruptible power supply. This insulation method using a high-frequency transformer does not require a low-frequency transformer, so it can be made smaller and lighter than the insulation method using a low-frequency transformer.

[Problems to be Solved by the Invention] However, when the transformer becomes excited at a high frequency, the loss of the transformer increases. The loss of this transformer consists of iron loss due to magnetic materials, copper loss due to windings, etc.The power conversion efficiency of the system of the uninterruptible power supply decreases due to the increase of these losses due to higher frequencies. Forgiveness, heat radiation measures for the loss are a problem.

 In addition, it has been pointed out that there are problems in the electromagnetic environment such as the leakage magnetic flux of the high frequency transformer affecting the display image of the computer, and the radiated electromagnetic field from the high frequency transformer giving disturbing noise to other electronic devices.

 On the other hand, even in the case of a high-frequency transformer, in principle, a heavy material such as a core and a winding conductor made of a magnetic material such as ferrite or cobalt-based amorphous is required, and these are required to reduce the size and weight of the UPS. It is an obstacle.

 Therefore, a main object of the present invention is to provide an uninterruptible power supply capable of reducing loss, an insulating method thereof, and a power feeding method thereof.

 Another object of the present invention is to provide an uninterruptible power supply, an insulation method therefor, and a power supply method for the same, which can improve an electromagnetic environment that does not give a fault noise to other electronic devices.

 Still another object of the present invention is to provide an uninterruptible power supply suitable for reduction in size and weight, an insulation method for the same, and a power supply method for the same.

[Means for Solving the Problems] The invention according to claim 1 supplies power to a load through an insulation circuit in a high-frequency switching power supply circuit that outputs high-frequency power based on power from an input power supply. In the uninterruptible power supply, the insulation circuit is composed of capacitors.

 According to a second aspect of the present invention, there is provided a first frequency conversion circuit that outputs high frequency power in response to an input power source, an insulation circuit connected to the output of the first frequency conversion circuit, and an output of the insulation circuit. In the uninterruptible power supply device, which is connected to, and includes a second frequency conversion circuit that outputs AC power, the insulation circuit is configured by a capacitor.

 The invention according to claim 3 is an uninterruptible power supply, which is connected to an output of a first frequency conversion circuit and a first frequency conversion circuit that frequency-converts power from a power supply and outputs high-frequency power. A second frequency conversion circuit for frequency-converting the high frequency power output from the first frequency conversion circuit to supply power to a load, an output of the first frequency conversion circuit and a second frequency conversion circuit Of the first frequency conversion circuit and an input of the second frequency conversion circuit and an input of the second frequency conversion circuit.

 According to a fourth aspect of the present invention, there is provided a first frequency conversion circuit for switching electric power from an input power supply to output electric power of a frequency higher than the input power supply, and an output of the first frequency conversion circuit. It is provided with a capacitor that is connected and through which the power of the high frequency passes, and a second frequency conversion circuit that frequency-converts the power of the high frequency that has passed through the capacitor and supplies the power to the load.

 The invention according to claim 5 is an uninterruptible power supply device, comprising: a first frequency conversion circuit that frequency-converts power from a power supply to output high-frequency power; and an output of the first frequency conversion circuit. A second frequency conversion circuit which is connected and supplies the electric power to a load by frequency-converting the high-frequency power output from the first frequency conversion circuit; and the output of the first frequency conversion circuit and the first frequency conversion circuit. It is connected to the input of the second frequency conversion circuit, and includes a capacitor that passes the high-frequency power but blocks the DC power.

 According to the sixth aspect of the present invention, the power from the input power source is converted into high-frequency AC power, and the high-frequency AC power is passed through the insulating barrier through the electric field.

 According to a seventh aspect of the present invention, the step of frequency-converting the power from the input power source into high-frequency power, the step of passing the high-frequency power through a capacitor, and the high-frequency power passed through the capacitor Converting the electric power of a certain frequency to the load and supplying it to the load.

A method for insulating an uninterruptible power supply device for insulating between a first frequency conversion circuit that outputs high-frequency power and a second frequency conversion circuit that supplies power to a load, the method including: It is connected to the frequency conversion circuit via a capacitor and insulated by the insulation barrier of the capacitor.

[Operation] According to the present invention, the high frequency power generated by the high frequency switching power supply circuit or the first frequency conversion circuit is supplied to the load side via the capacitor without passing through the high frequency transformer. An electric field is a main medium of electric energy when passing through the insulating barrier.

 Since the insulating barrier is formed using a dielectric material instead of using a magnetic material, a high-frequency alternating magnetic field is not generated compared to the conventional case where an insulating circuit is composed of a magnetic material. Therefore, iron loss and copper loss caused by winding current and winding resistance do not occur.

 Furthermore, since a winding coil that forms a high-frequency magnetic field can be eliminated, a strong high-frequency leakage flux is practically hardly generated.

[Embodiment of the Invention] FIG. 1 is an electric circuit diagram showing a first embodiment of the present invention. Referring to FIG. 1, the commercial AC power supply terminals T1 and T2 of the uninterruptible power supply device are connected to a high frequency component removing filter circuit F including a reactor FL and a capacitor FC. A reactor LA C for current control is connected to the output line of the filter circuit F.

 The first frequency conversion circuit PC1 includes a rectifier circuit 12 composed of four diodes D1, D2, D3, D4 connected in a bridge and first, second, third and fourth switches Q1, Q2, Q3 and Q4. And a high-frequency switching power supply circuit 15 connected in a bridge. The pair of AC input terminals of the first frequency conversion circuit PC1 are connected to the commercial AC power supply terminals T1 and T2 of the uninterruptible power supply through the reactor LAC and the filter circuit F. A high frequency switching power supply circuit 15 is connected between the pair of power lines 13 and 14 connected to the direct current output terminal of the rectifier circuit 12. Each of the switches Q1, Q2, Q3 and Q4 constituting the high frequency switching power supply circuit 15 is composed of a power MOSFET having a freewheeling diode built therein.

 The output terminal of the first frequency conversion circuit PC1, that is, the output terminal of the high frequency switching power supply circuit 15 is connected to the primary side terminals A and B of the insulating circuit 45, and the primary side terminal A of the insulating circuit 45 is connected. Is connected between the first and second switches Q1 and Q2, and the other primary side terminal B is connected between the third and fourth switches Q3 and Q4. A pair of input terminals of the second frequency conversion circuit PC2 is connected to the secondary side terminals C and D of the insulating circuit 45.

 The insulating circuit 45 is formed by connecting the primary side terminals A and B of the insulating circuit and the secondary side terminals C and D in series via capacitors C1 and C2, respectively. The capacitors C1 and C2 form an insulating barrier 44 between the primary side terminals A and B and the secondary side terminals C and D, and the secondary side terminals C and D with respect to the primary side terminals A and B. Electrically floats. Here, it should be noted that the current output from the high frequency switching power supply circuit 15 does not directly flow inside the capacitors C1 and C2, but rather an electric field as a medium in the dielectric inside the capacitors C1 and C2. To be transmitted to the other. That is, the dielectric material inside the capacitors C1 and C2 is the insulating material itself. Therefore, the high frequency power output from the high frequency switching power supply circuit 15 is transmitted to the second frequency conversion circuit PC2 side through the insulating barrier 44 formed of the capacitors C1 and C2 using the electric field as the power transmission medium. . The insulation barrier 44 formed by the capacitors C1 and C2 exhibits a practically infinite impedance with respect to direct current, and the high frequency makes the capacitors C1 and C2 extremely small in capacitance. As a result, it exhibits a substantially sufficiently large impedance even with low-frequency alternating current, especially with commercial frequencies (50 Hz or 60 Hz). Therefore, even if there is a potential difference between the ground on the input side and the ground on the output side, this insulating barrier 44 exists, so that the DC or low-frequency current flowing inside the uninterruptible power supply due to the potential difference between the two grounds. It is suppressed very effectively by this insulating barrier 44.

 The second frequency conversion circuit PC2 includes a high frequency rectifier circuit 70 including diodes D5, D6, D7 and D8, and a pair of input terminals of the high frequency rectifier circuit 70 are connected to terminals C and D of the insulation circuit 45. A smoothing capacitor C4 is connected between the pair of output power lines of the high frequency rectifier circuit 70. An inverter 77 and a power failure backup storage battery BT are connected between the DC output terminals 75 and 76 via a charging circuit 72. The charging circuit 72 is a charging circuit for the storage battery BT, more specifically, a charging current limiting circuit that limits the charging current, and is composed of a transistor and a resistor. A blocking diode DB is connected in parallel to the charging circuit 72. Normally, the storage battery BT is charged via the charging circuit 72.

When the input commercial power supply fails, the energy stored in the storage battery BT is supplied to the inverter 77 via the diode DB. The inverter 77 is a bridge connection of the fifth, sixth, seventh and eighth switches S1, S2, S3 and S4.

Each of the switches S1, S2, S3 and S4 is composed of a power MOSFET with a built-in freewheeling diode. The inverter 77 has an operating frequency higher than an audible frequency of about 20 kHz for noise reduction, and performs sine wave modulation to output an AC voltage having a constant frequency and a constant voltage. Detailed description is omitted. The AC power output from the inverter 77, that is, the AC power output from the second frequency switching circuit PC2 is supplied to the load via the load terminals T3 and T4. The AC power output from the second frequency conversion circuit PC2 and supplied to the load is supplied to the load via the filter because it contains unnecessary harmonic components due to switching, but this filter circuit and the load are It is omitted in the figure.

 The first, second, third and fourth switches Q1, Q2, Q3 and Q4 of the high frequency switching power supply circuit 15 described above are inverter-controlled and short-circuit controlled. The short-circuit control is to turn on the first switch Q1 and the second switch Q2 at the same time and to turn on the third switch Q3 and the fourth switch at the same time in order to control the current flowing through the reactor LAC. By doing. In the inverter control, in order to output high-frequency AC power, the first switch Q1 and the fourth switch Q4 are simultaneously turned on, and the second switch Q2 and the third switch Q3 are turned on. At the same time, the state of being on is alternately repeated, so-called inverter operation for converting direct current to alternating current is performed.

 In order to perform both inverter control and short circuit control of the high frequency switching power supply circuit 15, a current detector 27 for detecting the current i2 flowing in the output line of the filter circuit F is provided between the filter circuit F and the rectification circuit 12. It is provided in. An input voltage detection circuit 28 is connected to the commercial AC power supply terminals T1 and T2 in order to obtain a reference sine wave for comparison with the detection current i2. The output detection voltage circuit 31 is connected to the DC output terminals 75 and 76 for detecting the output DC voltage of the high frequency rectifier circuit 70.

 The current detector 27 is connected to one input terminal (inverting input terminal) of the first error amplifier 35 via the absolute value circuit 34. The output line of the input voltage detection circuit 28 is connected to the other input terminal (non-inverting input terminal) of the first error amplifier 35 via the absolute value circuit 36 and the multiplication circuit 37. The first error amplifier 35 produces an output corresponding to the difference between the current i2 containing a small ripple component and the sinusoidal voltage.

 In order to control the high frequency switching power supply circuit 15 so as to keep the output voltage of the high frequency rectifier circuit 70 constant, the output line of the output voltage detection circuit 31 is connected to one input terminal (inverting input) of the second error amplifier 38. The reference voltage source 39 is connected to the other input terminal (inverting input) of the error amplifier 38.

The second error amplifier 38 generates an output voltage corresponding to the difference between the detected voltage and the reference voltage and sends it to the multiplier 37. The multiplier 37 gives a value obtained by multiplying the amplitude of the reference sine wave waveform given from the absolute value circuit 36 by the output of the second error amplifier 38 to the non-inverting input terminal of the first error amplifier 35.

 One input terminal (inverting input) of the voltage comparator 40 is connected to the output terminal of the first error amplifier 35 via the low pass filter 43, and the other input terminal (non-inverting input) of the sawtooth wave generation circuit 41. It is connected. This comparator 40 outputs the comparison output of both inputs in a binary format.

 The switch control signal forming circuit 42 connected to the output terminal of the comparator 40 and the output terminal of the sawtooth wave generating circuit 41 switches the switches Q1 to Q4 based on the output of the comparator 40 and the output of the sawtooth wave generating circuit 41. Form the control signal of. Although not shown, the output line of the control signal forming circuit 42 is connected to the control terminals (gates) of the switches Q1 to Q4.

 FIG. 2 is a timing chart for explaining the operation of the uninterruptible power supply system of FIG. Next, the operation of the uninterruptible power supply system shown in FIG. 1 will be described with reference to FIG. The high-frequency switching power supply circuit 15 generates high-frequency power, so that the sawtooth wave generation circuit 41 generates commercial sawtooth wave repetition frequency commercial AC power supply terminals T1 and T2 to reduce the size and weight of the insulating circuit 45. Set it sufficiently higher than the frequency of the commercial AC power supplied from. Therefore, the current i2 flowing through the reactor LAC in FIG. 1 has a waveform including small ripples of high frequency corresponding to the on / off control of the switches Q1 to Q4 of the high frequency switching power supply circuit 15.

However, since the filter circuit F is included, harmonic components are removed and the input current i1 becomes an approximate sine wave.

 When the circuit of FIG. 1 is operated, the sawtooth wave generation circuit 41 outputs the sawtooth wave A2 shown in FIG. 2A, the control signal of the first switch Q1 of FIG. The control signal of the third switch Q3 shown in FIG. 7C is fixedly generated in synchronization with each other. In the inverter operation of a general voltage source inverter, the phase inversion signal of the control signal of the first switch Q1 shown in FIG. 2 (B) is added to the second switch Q2, and the fourth switch Q4 is added. Although the phase inversion signal of the control signal of the third switch Q3 shown in FIG. 2 (C) is added, in the high frequency switching power supply circuit 15 according to the present embodiment, as shown in FIG. 2 (D) (E), A control signal having a phase difference of more than 180 degrees with respect to the first and third switches Q1 and Q3 is applied to the second and fourth switches Q2 and Q4.

This is because the high frequency switching power supply circuit 15 of the present embodiment is not a voltage type inverter but is similar in principle to a current type inverter. That is, the high frequency switching power supply circuit 15 uses the magnetic energy of the reactor LAC as the input energy. Then, the current flowing through this reactor LAC transiently acts as a current source. Therefore, the inverter operation of the current source inverter must be used as the inverter operation.

 The control signals shown in FIGS. 2D and 2E are formed based on the first error amplifier 35 and the comparator 40.

The current detection signal F1 including the ripple shown in FIG. 2 (F) is input to one input terminal of the error amplifier 35, and the reference sine wave F2 shown in FIG. 2 (F) is input from the multiplier 37 to the other input terminal. When input, a signal A1 containing information on the input current i2 and information on the output voltage is obtained at the output stage of the low-pass filter 43 connected to the output terminal of the error amplifier 35. As shown in FIG. 2 (A), when the signal A1 and the sawtooth wave A2 of FIG. 2 (A) obtained from the sawtooth wave generation circuit 41 are compared by the comparator 40, the signal A1 is compared with the sawtooth wave A2. The output of the comparator 40 is switched every time the signal crosses.

That is, the output of the comparator 40 becomes high level during the period of t1 to t2, t3 to t4, etc. when the sawtooth wave A2 becomes higher than the signal A1. The control signal forming circuit 42 forms the control signals for the second and fourth switches Q2 and Q4 shown in FIGS. 2D and 2E based on the output of the comparator 40. That is, at t1, the control signal of the second switch Q2 is returned to the low level in response to the inversion of the output of the comparator 40, and conversely the control signal of the fourth switch Q4 is inverted to the high level. At time t3, when the output of the comparator 40 changes to the high level again, the control signal of the second switch Q2 is changed to the high level and the control signal of the fourth switch Q4 is changed to the low level. The points of time t2, t4, etc. at which the sawtooth wave A2 crosses the level of the signal A1 in the downward direction from the high level are independent of the control signals of the second and fourth switches Q2, Q4. Therefore, the control signals of the second and fourth switches Q2 and Q4 in FIGS. 2D and 2E are formed by flip-flop circuits triggered by t1, t3 and t5.

 During the period from t0 to t1 and t4 to t5, both the first and second switches Q1 and Q2 are turned on, so that the DC lines 13 and 14 are short-circuited by the switch Q1 and Q2. As a result, the current i2 flowing through the reactor increases as shown in FIG. 2 (F). During the period from t1 to t2, the second switch Q2 is turned off, the short circuit is released, and the current passing through the first switch Q1 is switched via the capacitor C 1, the high frequency rectifier circuit 70 and the capacitor C2. Therefore, the electromagnetic energy stored in the reactor LA C reaches Q4 and is transmitted to the high-frequency rectification circuit 70 side by using the electric field on the insulation barrier wall 44 formed in the insulation circuit 45 including the capacitors C1 and C2 as a power transmission means. Is generated and is absorbed on the high frequency rectification circuit 70 side, the current i2 decreases.

 When both the third switch Q3 and the fourth switch Q4 are turned on at t2 to t3, the short circuit is formed again, and the current i2 increases again. However, when the fourth switch Q4 is turned off at t3, the current passing through the third switch Q3 reaches the switch Q4 via the capacitor C2, the high frequency rectifier circuit 70 and the capacitor C1, and therefore the electromagnetic wave stored in the reactor LAC is stored. Energy is transmitted to the high frequency rectification circuit 70 side by using an electric field as an electric power transmission means on the insulating barrier 44 formed of the capacitors C1 and C2, and the magnetic energy stored in the reactor LA C on the high frequency rectification circuit 70 side. Is absorbed, the current i2 decreases again. The commercial AC power supply voltage changes in a sine wave shape, and since this is applied to the error amplifier 35 as a reference, the current i2 also changes in a sine wave shape. Therefore, in the case of this embodiment, the waveform of the input current i 2 can be approximated to a sine wave.

 When the detection value of the DC output voltage detection circuit 31 changes, the output level of the second error amplifier 38 changes, the output level of the multiplier 37, that is, the amplitude of the reference sine wave, changes, and the short-circuit time width α is adjusted. To be done.

 As described above, in the uninterruptible power supply system according to this embodiment, since the insulating barrier 44 is composed of the capacitors C1 and C2, the ferrite, amorphous and the like necessary for composing the core of the high frequency transformer. In principle, heavy materials such as the magnetic material and the coil of wire forming the winding are not required. Therefore, in principle, it is possible to reduce the weight and size of the insulation circuit.

 Also, in the case of an insulating circuit consisting of a capacitor, iron loss and copper loss are hardly generated, and the main loss is the dielectric loss. In principle, the loss can be reduced. The loss can be effectively reduced by using pyrene, film, or capacitor.

 Furthermore, in the case of an insulating circuit composed of a capacitor, a leakage magnetic field of high frequency intensity is substantially not generated as compared with the insulating circuit, so that good results can be obtained in terms of the electromagnetic environment.

 FIG. 3 is an electric circuit showing a second embodiment of the uninterruptible power supply. The embodiment shown in FIG. 3 has the same configuration as that of FIG. 1 except for the following points. That is, the commercial AC power supply terminals T1 and T2 are connected to a pair of alternating input terminals of the first frequency conversion circuit PC11, that is, a pair of rectifier circuits 12 including four diodes D1, D2, D3 and D4 which are bridge-connected. The AC input terminal is connected.

A smoothing capacitor CD is connected between the pair of DC lines 13 and 14 connected to the DC output terminal of the rectifier circuit 12 to remove harmonics, and bridges the first to fourth switches Q1 to Q4. The connected high frequency switching power supply circuit 15 is connected via the reactor LDC.

 A current detector 27 for detecting the current i3 flowing in the reactor LDC is provided between the smoothing capacitor CD and the reactor LDC. The current detector 27 is connected to one input terminal (inverting input terminal) of the first error amplifier 35. Further, the second error amplifier 38 generates an output voltage corresponding to the difference between the detected voltage and the reference voltage, and supplies this as a reference current to the non-inverting input terminal of the first error amplifier 35.

 FIG. 4 is a timing chart for explaining the operation of the uninterruptible power supply system shown in FIG.

 Next, the operation of the uninterruptible power supply shown in FIG. 3 will be described with reference to FIG. 4, but since most of the operation is the same as the uninterruptible power supply shown in FIG. Only different parts will be described.

A commercial AC power supply is input to the commercial AC power supply terminals T1 and T2, is rectified by four diodes D1 to D4, a high frequency component is removed by a smoothing capacitor CD, and a DC voltage is a high frequency switching power supply circuit 15 via a reactor LDC. The high frequency switching power supply circuit 15 generates high frequency power.

 As shown in FIG. 4 (F), the current detection signal F3 including the ripple is input to one input terminal of the error amplifier 35, and the second error is input to the other input terminal. The reference current F4 shown in FIG. 4 (F) is input from the amplifier 38. Then, at the output stage of the low-pass filter 43 connected to the output terminal of the error amplifier 35, the signal A1 including the information of the input current i3 and the information of the output voltage of the high frequency rectifier circuit 70 is obtained. As shown in FIG. 4 (A), when the signal A1 and the sawtooth wave A2 shown in FIG. 4 (A) obtained from the sawtooth wave generation circuit 41 are compared by the comparator 40, the signal A1 is converted into the sawtooth wave A2. The output of the comparator 40 changes every time it crosses. That is, when the sawtooth wave A2 becomes higher than the signal A1, the output of the comparator 40 becomes high level during the period of t1 to t2, t3 to t4 and the like. Thereafter, the same operation as in FIG. 1 is performed.

 FIG. 5 is an electric circuit showing a third embodiment of the uninterruptible power supply. The embodiment shown in FIG. 5 has the same structure as that of FIG. 1 except for the following points. That is, the commercial AC power supply terminals T1 and T2 are connected to a pair of alternating input terminals of the first frequency conversion circuit PC12, that is, a pair of rectifier circuits 12 including four diodes D1, D2, D3 and D4 which are bridge-connected. The AC input terminal is connected.

Smoothing capacitors CD1 and CD2 are connected in parallel to the diodes D3 and D4 of the rectifying circuit 12 in order to double-rectify the input commercial AC power supply. A high-frequency switching power supply circuit 15 in which first to fourth switches Q1 to Q4 are bridge-connected is connected between the pair of DC lines 13 and 14 connected to the DC output terminal of the rectifier circuit 12. A smoothing capacitor C4 is connected via a reactor LDC1 between a pair of output power lines of a frequency rectification circuit 70 composed of diodes D5, D6, D7, D8 in the second frequency conversion circuit PC21.

 The error amplifier 38 generates an output voltage corresponding to the difference between the detection voltage of the output voltage detection circuit 31 and the reference voltage of the reference voltage source 39, and sends it to one input terminal (inverting input) of the voltage comparator 40. The comparator 40 outputs a comparison output of both inputs from the sawtooth wave generation circuit 41 and the error amplifier 38 in a binary format. The switch control signal forming circuit 42 1, which is connected to the output terminal of the comparator 40 and the output terminal of the sawtooth wave generating circuit 41, switches the switches Q1 to Q4 based on the outputs of the comparator 40 and the sawtooth wave generating circuit 41. Form the control signal. The first, second, third and fourth switches Q1, Q2, Q3 and Q4 of the high frequency switching power supply circuit 15 are controlled by an inverter and control for changing the pulse width of the output voltage, so-called pulse width. Controlled.

 FIG. 6 is a timing chart for explaining the operation of the uninterruptible power supply system shown in FIG.

 Next, the operation of the uninterruptible power supply device shown in FIG. 5 will be described with reference to FIG. A commercial AC power supply is input to the commercial AC power supply terminals T1 and T2, is double-voltage rectified by two diodes D1 and D2, a high frequency component is removed by smoothing capacitors CD1 and CD2, and a doubled current voltage is obtained. The high frequency switching power supply circuit 15 supplies the high frequency switching power supply circuit 15 with high frequency power. When the circuit of FIG. 5 is operated, the sawtooth wave generation circuit 41 outputs the sawtooth wave A2 shown in FIG. 6A, the control signal of the first switch Q1 of FIG. The control signal of the second switch Q2 shown in FIG. 6C is fixedly generated in synchronization with each other. Then, the phase inversion signal of the control signal of the first switch Q1 shown in FIG. 6 (B) is added to the second switch Q2, and the third switch shown in FIG. 6 (E) is added to the fourth switch Q4. The phase inversion signal of the control signal of the switch Q3 is added. In other words, it operates as a general voltage inverter. This is because the high frequency switching power supply circuit 15 of the present embodiment is a voltage type inverter, and the electrostatic energy of the smoothing capacitors CD1 and CD2 is used as the direct input power energy, and the voltage of the smoothing capacitors CD1 and CD2 is Is a pseudo voltage source. Therefore, the inverter operation of the voltage source inverter must be used as the inverter operation.

 The control signals of FIGS. 6D and 6E are formed based on the output of the comparator 40. As shown in FIG. 6 (A), when the signal A1 obtained from the error amplifier 38 and the sawtooth wave A2 obtained from the sawtooth wave generation circuit 41 are compared by the comparator 40, the sawtooth wave A2 crosses the signal A1. The output of the comparator 40 changes every time. That is, the output of the comparator 40 becomes high level during the period of t1 to t2, t3 to t4, etc. when the sawtooth wave A2 becomes higher than the signal A1. The control signal forming circuit 421 forms the control signals of the fourth and third switches Q4 and Q3 shown in FIGS. 2D and 2E based on the output of the comparator 40. That is, in response to the output of the comparator 40 being inverted at t1, the control signal of the fourth switch Q4 is returned to the low level, and conversely, the control signal of the third switch Q3 is inverted to the high level. At time t3, when the output of the comparator 40 changes to the high level again, the control signal of the fourth switch Q4 is changed to the high level and the control signal of the third switch Q3 is changed to the low level. The points of time t2, t4, etc. at which the sawtooth wave A2 crosses the level of the signal A1 from higher to lower are independent of the control signals of the fourth and third switches Q4, Q3. Therefore, the control signals of the fourth and third switches Q4 and Q3 in FIGS. 6D and 6E are formed by flip-flops triggered by t1, t3 and t5.

 During the period from t0 to t1, both the first and fourth switches Q1 and Q4 are turned on, so that the voltage between the DC lines 13 and 14 is output from the high frequency switching power supply circuit 15. Then, electric power is transmitted to the high-frequency rectifier circuit 70 side by using the electric field on the insulating barrier 44 formed in the insulating circuit 45 including the capacitors C1 and C2 as a power transmitting means.

 During the period from t1 to t2, both the first and third switches Q1 and Q3 are turned on, so that the voltage between the DC lines 13 and 14 is not output from the high frequency switching power supply circuit 15. That is, the output voltage of the high frequency switching power supply circuit becomes zero voltage.

 When the second switch Q2 and the third switch Q3 are simultaneously turned on at t2 to t3, the voltage between the DC lines 13 and 14 is again output from the high frequency switching power supply circuit, but the polarity of the output voltage is The polarity is opposite to that of the output voltage from t0 to t1.

 During the period from t3 to t4, both the second and fourth switches Q2 and Q4 are turned on, so that the voltage between the DC lines 13 and 14 is not output from the high frequency switching power supply circuit 15. That is, the output voltage of the high frequency switching power supply circuit 15 becomes zero voltage.

 By repeating the above series of operations, the high frequency voltage is output from the high frequency switching power supply circuit 15. When the detection value of the DC output voltage detection circuit 31 changes, the output level of the second error amplifier 38 changes, and the time width θ of the output voltage is adjusted.

 FIG. 7 is an electric circuit showing a fourth embodiment of the uninterruptible power supply. The embodiment shown in FIG. 7 has the same structure as that of FIG. 5 except for the following points. That is, the storage battery BT for power failure backup is connected via the charging circuit 72 between the pair of DC lines 13 and 14 of the first frequency conversion circuit PC13. A blocking diode DB is connected in parallel to the charging circuit 72. Therefore, the second frequency conversion circuit PC22 is not equipped with a storage battery or the like for power failure backup.

 Next, the operation of the uninterruptible power supply system shown in FIG. 7 will be described. The operation of FIG. 7 is the same as the operation of the uninterruptible power supply device of FIG. 5 except for the operation at the time of power failure, so only the operation at the time of power failure will be described. When the input commercial power supply fails, the energy stored in the storage battery BT is converted into high-frequency power by the high-frequency switching power supply circuit 15 via the diode DB and transmitted to the second frequency conversion circuit PC22. This high-frequency power is frequency-converted by the second frequency conversion circuit PC22 and then supplied to the load. Thereafter, the same operation as in FIG. 5 is performed.

 FIG. 8 is a circuit diagram of the fifth embodiment of the present invention.

In this embodiment, a filter is provided at the output of the inverter 77, the input power source side, that is, the input terminal T2 is connected to the ground G1, the output load side, that is, the output terminal T4 is connected to the ground G2, and both grounds G1 are connected. , G2 are connected via an impedance Z, and the rest of the configuration is the same as in FIG.

 In FIG. 8, the filter at the output of the inverter 77 is composed of reactors LI1 and LI2 and a capacitor CI. Reactor LI1 is provided in the power line that connects the connection point between switch S1 and switch S2 and output terminal T3. Reactor LI2 is provided in a power line that connects the connection point between switch S3 and switch S4 and output terminal T4. The capacitor CI is connected between the output terminals T3 and T4.

 Next, the operation of the embodiment shown in FIG. 8 will be described. Since the operation common to FIG. 1 is the same, only different parts will be described. The AC power output from the inverter 77, that is, the AC power output from the second power frequency conversion circuit PC2 contains a large amount of normal mode and common mode harmonic components due to switching.

Therefore, electric power is supplied from the output terminals T3 and T4 to the load side through the filter constituted by the reactors LI1 and LI2 and the capacitor CI. The reactors LI1 and LI2 and the capacitor CI constituting the filter have high impedance and the capacitor CI has low impedance with respect to the switching frequency of the inverter 77, respectively. As a result, the ripple voltage component of the switching frequency output from the inverter 77 is removed, and a smooth sinusoidal AC voltage having a commercial frequency is supplied to the load.

 Here, the role of the reactors L I1 and LI2 provided in the power line will be described in detail.

Reactor LI1 and reactor LI2 cut off the input and output of the uninterruptible power supply at high frequency. One reactor of the reactor LI1 or the reactor LI2 has an infinite impedance Z between the ground G1 connected to the input terminal T2 and the ground G2 connected to the output terminal T4, that is, the ground G1 and the ground G2. It is basically unnecessary if is completely electrically independent.

 However, when the impedance Z is not high impedance with respect to the switching frequency of the high frequency switching power supply circuit 15 or the switching frequency of the inverter 77, the reactors LI1 and L I2 play an important role. When the impedance Z is low impedance with respect to the switching frequency of the high frequency switching power supply circuit 15 and the reactor LI1 or the reactor LI2 is not provided, the capacitors C1 and C2 forming the insulation barrier 44 are formed. The electric charge stored in the high frequency switching power supply circuit 15 becomes a large common mode current through the impedance Z every time the switching operation of the high frequency switching power supply circuit 15 flows, and flows between the input and output grounds.

 Furthermore, a large amount of common mode current flows from the inverter 77 through the impedance Z through the capacitors C 1 and C2 each time the switching operation of the inverter 77 is performed. As a result, a large amount of high-frequency common-mode current will flow through the switch forming the high-frequency switching power supply circuit and the switch forming the inverter 77.

However, by installing the reactor LI1 and the reactor LI2 in each power line, the input and output of the non-stop power supply device are cut off at a high frequency, which solves this problem.

 That is, if the inductance values of the reactors LI1 and LI2 are respectively high impedances with respect to the switching frequency of the high frequency switching power supply circuit 15 and the switching frequency of the inverter 77, the capacitor C1 is switched each time the high frequency switching power supply circuit 15 switches. , The common current flowing by the electric charge stored in C2 is effectively blocked by the reactors LI1 and LI2. That is, the input and output of the uninterruptible power supply unit are cut off at a high frequency by the reactor LI1 and the reactor LI2. Therefore, due to the reactors LI1 and LI2, the voltage of the capacitors C1 and C2 does not abruptly change due to the high-frequency current in the common mode, and the voltage of the capacitor forming the insulation barrier 44 is stabilized.

 FIG. 9 is an electric circuit diagram showing a sixth embodiment of the present invention. In FIG. 8, the output side filter is used to shut off the input and output of the uninterruptible power supply in a high frequency manner. However, in the embodiment shown in FIG. 9, the input side filter circuit FX is used to generate a high frequency wave. The input and output are cut off.

 Referring to FIG. 9, a filter circuit FX including reactors FL1 and FL2 and a capacitor FC is connected to input terminals T1 and T2. Reactor FL1 is connected to input terminal T1, and reactor FL2 is connected to input terminal T2. Further, a filter including a reactor L1 and a capacitor CI is connected to the inverter 77, the reactor LI is connected between the inverter 77 and the output terminal T3, and the capacitor CI is connected between the output terminals T3 and T4. Therefore, in the case of the present embodiment, the input and output of the uninterruptible power supply device are cut off at high frequency by the reactors FL1 and FL2 forming the filter circuit FX on the input side. In FIG. 9, the other main circuit configuration is the same as that in FIG. 1, and the control circuit is omitted because it is the same as that in FIG.

 Similar to FIG. 8, in FIG. 9 as well, the impedance Z between the grounds G1 and G2 is low with respect to the switching frequency of the high-frequency switching power supply circuit 15, and one of the reactor FL1 and the reactor FL2 is also connected. When the reactor is not provided, the electric charge accumulated in the capacitors C1 and C2 forming the insulating barrier 44 becomes a large common mode current via the impedance Z each time the switching operation of the high frequency switching power supply circuit 15 is performed. You can run between the input and output grounds. Furthermore, a large amount of common mode current flows from the inverter 77 through the impedance Z through the capacitors C1 and C2 every time the switching operation of the inverter 77 is performed. As a result, a large amount of high-frequency common-mode current flows in the switch that constitutes the high-frequency switching power supply circuit 15 and the switch that constitutes the inverter 77. However, by installing the reactor FL1 and the reactor FL2 in the power line on each input side, the input and output of the uninterruptible power supply are cut off at a high frequency, and this problem is solved. That is, if the inductors of the reactors FL1 and FL2 have high impedance with respect to the switching frequency of the high frequency switching power supply circuit 15 and the switching frequency of the inverter 77, respectively, the switching of the high frequency switching power supply circuit 15 will be performed. Each time, the common current flowing due to the electric charge stored in the capacitors C1 and C2 is effectively blocked by the reactors FL 1 and FL2. In other words, the input and output of the uninterruptible power supply system are cut off at high frequencies by the reactor FL1 and the reactor FL2. Therefore, due to the reactors FL1 and FL2, the voltage of the capacitors C1 and C2 does not suddenly change due to the high-frequency current in the common mode, and the voltage of the capacitor forming the insulation barrier 44 is stabilized.

 FIG. 10 is an electric circuit diagram showing a seventh embodiment of the present invention. In Fig. 8 and Fig. 9, the reactor of the filter circuit was used to shut off the input and output of the uninterruptible power supply at high frequency, but in the embodiment shown in Fig. 10, the input side current control The reactors LAC1 and LAC2 are used to disconnect the input and output at high frequencies. With reference to FIG. 10, a filter circuit F including a reactor FL and a capacitor FC is connected to the input terminals T1 and T2. Reactors LAC1 and LAC2 connected to the output power line of each filter circuit F are used for current control and for the purpose of high frequency cutoff between the input and output of the UPS. It In FIG. 10, the other main circuit configuration is the same as that in FIG. 9, and the description of the control circuit is omitted because it is the same as that in FIG.

 As in FIGS. 8 and 9, also in FIG. 10, the impedance Z between the grounds G1 and G2 is low with respect to the switching frequency of the high frequency switching power supply circuit 15, and the reactor LAC1 or When one reactor of the reactor LAC2 is not provided, the electric charge stored in the capacitors C1 and C2 forming the insulating barrier 44 is significantly common mode via the impedance Z at each switching operation of the high frequency switching power supply circuit 15. It becomes a current and flows between the input and output grounds. Furthermore, a large amount of common mode current flows from the inverter 77 through the impedance Z through the capacitors C1 and C2 each time the inverter 77 switches. As a result, a large amount of high-frequency common-mode current flows through the switch that constitutes the high-frequency switching power supply circuit and the switch that constitutes the inverter 77. However, by installing the reactor LAC1 and the reactor LAC2 in each power line on the input power supply side, the input and output of the uninterruptible power supply are cut off at high frequency, and this problem is solved. That is, if the values of the inductances of the reactors L AC1 and LAC 2 are high impedances with respect to the switching frequency of the high frequency switching power supply circuit 15 and the switching frequency of the inverter 77, respectively, the frequency of switching of the high frequency switching power supply circuit 15 is changed. The common current flowing due to the electric charges stored in the capacitors C1 and C2 is effectively blocked by the reactors LAC1 and LAC2. In other words, the input and output of the uninterruptible power supply are cut off at high frequency by the reactor LAC1 and the reactor LAC2. Therefore, due to reactors LAC 1 and LAC 2, the voltage of the capacitors C 1 and C 2 does not suddenly change due to the high frequency current in the common mode, and the voltage of the capacitor forming the insulating barrier 44 is stabilized.

 Note that specific application examples of the method of using a reactor to cut off the input and output of the uninterruptible power supply at high frequency and suppress the common mode current passing through the insulation barrier are shown in Figs. The embodiment is not limited to the embodiment shown in FIG. 10 and various modifications can be made. For example, even if reactors are inserted in the respective power lines 13 and 14 in the power frequency conversion circuit PC1 of FIG. 1, it is possible to suppress the high frequency common mode current from passing through the insulating barrier 44 in the same manner. In short, the power line between the input and output of the uninterruptible power supply should have a reactor that cuts off the input and output of the uninterruptible power supply at high frequencies.

 FIG. 11 is an electric circuit diagram showing an eighth embodiment of the present invention. In FIG. 11, a common mode choke LC is provided on the power line between the filter circuit F and the frequency conversion circuit PC1, and the input power source side, that is, the input terminal T2 is connected to the ground G1, and the output load side, that is, the output terminal T4 is connected. It is connected to the ground G 2 and further, the two grounds G 1 and G 2 are connected via an impedance Z.

In FIG. 11, the other main circuit configuration is the same as that in FIG. 1, and the description of the control circuit is omitted because it is the same as that in FIG.

 In FIG. 11, the common mode choke LC has a high impedance in common mode inductance with respect to the switching frequency of the high frequency switching power supply circuit 15 and the switching frequency of the inverter 77. As a result, the common mode current flowing by the electric charge stored in the capacitors C1 and C2 each time the high frequency switching power supply circuit 15 switches is effectively cut off by the common mode choke L C. Furthermore, the common mode high frequency current flowing through the impedance Z due to the high frequency common mode voltage output by the switching operation of the inverter 77 is also effectively blocked by the common mode choke LC. Becomes Therefore, the voltage of the capacitors C1 and C2 does not suddenly change due to the common mode choke LC, and the voltage of the capacitor forming the insulating barrier 44 is stabilized.

 FIG. 12 is an electric circuit diagram showing a ninth embodiment of the present invention. In the embodiment shown in FIG. 12, the inverter 77 and the output terminal T3 are replaced with the power line between the filter circuit F and the frequency conversion circuit PC 1 where the common mode choke LC shown in FIG. 11 is inserted. , T4 is provided with a common mode choke LC on the output power line, and ground G1 and ground G2 are short-circuited by impedance Z1. Other main circuit configurations are shown in Fig. 11. Is the same as. Also in FIG. 12, the control circuit is omitted as in FIG. 11.

 Similar to the common mode choke LC of FIG. 11, the common mode choke LC of FIG. 12 has a high impedance of the common mode inductance with respect to the switching frequency of the high frequency switching power supply circuit 15 and the switching frequency of the inverter 77. As a result, similarly to the description of FIG. 11, the common mode voltage of the capacitors C1 and C2 does not fluctuate rapidly, and the voltage of the capacitor forming the insulating barrier 44 is stabilized.

 The common mode choke LC may be incorporated in the first power frequency conversion circuit PC1 or the second power frequency conversion circuit PC2 without being limited to the embodiment shown in FIGS. May be incorporated into. Alternatively, in FIG. 11, the arrangement of the filter circuit F and the common mode choke LC may be exchanged, and the point is that the common mode choke LC is provided in the power line between the input terminals T1 and T2 and the output terminals T3 and T4. The purpose of the description disclosed in FIGS. 11 and 12 can be achieved if they are arranged and exhibit a high impedance with respect to common mode.

 The present invention is not limited to the specific embodiment shown in FIGS. 1 to 12, but infinite variations and modifications are possible. That is, those skilled in the art can perform various other implementations without departing from the spirit and scope of the inventive idea by using other high-frequency switching power supply circuit of more complicated or simple structure. The mode can be realized. Further, the insulating circuit and the first and second frequency converting circuits are not limited to the illustrated embodiment, and an insulating circuit having another structure and first and second high frequency converting circuits having other structures are used. Thus, the invention described above can be implemented. For example, if insulation between the input and output of the non-stop power supply is not required, naturally one of the pair of capacitors forming the insulation barrier can be omitted.

"Effects of the Invention" As described above, the present invention does not require a high frequency transformer in principle. As a result, in principle, it is not necessary to use the magnetic materials such as amorphous and ferrite necessary for forming the core of the high frequency transformer and the heavy weight such as copper wire coils necessary for forming the winding. Therefore, in principle, the weight and size of the insulating circuit can be reduced.

 Also, in the case of an insulating circuit consisting of a capacitor, iron loss and copper loss are hardly generated, and the main loss is the dielectric loss. In principle, the loss can be reduced. The loss can be effectively reduced by using pyrene, film, or capacitor.

 Furthermore, in the case of an insulating circuit composed of a capacitor, a leakage magnetic field of high frequency intensity is substantially not generated as compared with the insulating circuit, so that good results can be obtained in terms of the electromagnetic environment.

[Brief description of drawings]

 FIG. 1 is a circuit diagram showing a first embodiment of the present invention. FIG. 2 is a timing chart for explaining the operation of the uninterruptible power supply system shown in FIG. FIG. 3 is a circuit diagram showing a second embodiment of the present invention. FIG. 4 is a timing chart for explaining the operation of the uninterruptible power supply system shown in FIG. FIG. 5 is a circuit diagram showing a third embodiment of the present invention. FIG. 6 is a timing diagram for explaining the operation of the uninterruptible power supply system shown in FIG. FIG. 7 is a circuit diagram showing a fourth embodiment of the present invention. FIG. 8 is a circuit diagram showing a fifth embodiment of the present invention. FIG. 9 is a circuit diagram showing a sixth embodiment of the present invention. FIG. 10 is a circuit diagram showing a seventh embodiment of the present invention. FIG. 11 is a circuit diagram showing an eighth embodiment of the present invention. FIG. 12 is a circuit diagram showing a ninth embodiment of the present invention. In the figure, PC1, PC2, PC11, PC12, PC21 and PC22 are frequency conversion circuits, 12, 70 are rectifier circuits, 15 is a high frequency switching power supply circuit, 44 is an insulation barrier, 45 is an insulation circuit, and B T is a storage battery. LC is a common mode choke, LAC1, LAC2, LI1, LI2, FL1, FL2 are reactors.

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[Procedure amendment]

[Date of submission] Hei 2,7,2 (1) Amend the claims as attached. (2) “6th line, 6th line to 9th line, 15th page of the description”
Invention according to claim :. Is corrected to the following sentence. The invention according to claim 6 is an uninterruptible power supply according to claim 2 or 3, further comprising a filter circuit connected to suppress or suppress the common mode current passing through the insulating circuit. The invention according to claim 7 is the uninterruptible power supply device according to claim 2, 3 or 6, wherein the first frequency conversion circuit includes a rectification circuit for rectifying the input power supply, A high-frequency switching power supply circuit for switching the rectified output of the rectifier circuit to output high-frequency power The invention according to claim 8 is an uninterruptible power supply device according to claim 2, 3 or 6. The second frequency conversion circuit is based on the rectifier circuit that rectifies the high frequency power that has passed through the insulation circuit, the storage battery that discharges during a power failure, and the output from the rectifier circuit when the power is turned on. The invention according to claim 9 is an uninterruptible power supply according to claim 6, wherein the filter circuit has an input power supply and a first frequency. The invention according to claim 10 is the uninterruptible power supply according to claim 6, wherein the filter circuit is between the second frequency conversion circuit and the load. The invention according to claim 11 relates to claim 6, 9 or 1.
An 0 uninterruptible power supply, wherein the filter circuit comprises a common mode choke connected to suppress or suppress common mode current passing through the isolation circuit. The invention according to claim 12 is claim 6, 9 or 1
An 0 uninterruptible power supply, wherein the filter circuit comprises a reactor connected to suppress or suppress the common mode current passing through the isolation circuit. The invention according to claim 13 is characterized in that the power from the input power source is converted into high frequency alternating current power, and the high frequency alternating current power is passed through an insulating barrier through an electric field. It is a method of insulating a power supply device. The invention according to claim 14 is an insulation method for an uninterruptible power supply device, which comprises a step of converting electric power from an input power source into electric power of a frequency higher than that of the input power source, and an insulating method of forming the electric power of the high frequency with a capacitor. It is a method of insulating an uninterruptible power supply device, which comprises the steps of passing through a barrier and converting high-frequency power that has passed through an insulating barrier into power of a lower frequency than high-frequency power. The invention according to a fifteenth aspect is the method for insulating an uninterruptible power supply according to the fourteenth aspect, further comprising a step of suppressing or suppressing a common mode current passing through the insulation barrier. The invention according to claim 16 is an insulation method for an uninterruptible power supply according to claim 15, wherein the common mode current is suppressed or suppressed by using the common mode choke. The invention according to claim 17 is an insulation method for an uninterruptible power supply according to claim 15, wherein common mode current is suppressed or suppressed by using a reactor. The invention according to claim 18 is claim 14 or 15.
The method for insulating an uninterruptible power supply device according to claim 1, wherein the high-frequency power is power at an audible frequency or higher. A nineteenth aspect of the present invention is a method for supplying power to an uninterruptible power supply device, the method including: frequency-converting electric power from an input power source into electric power having a high frequency; and passing electric power having a high frequency through a capacitor, And converting the high-frequency power that has passed through the capacitor to feed the load. The invention according to claim 20 is a method for supplying power to an uninterruptible power supply, comprising the steps of: responding to an input power source, converting the power from the input power source into high frequency power; and converting the high frequency power into a capacitor. And the step of converting the high-frequency power that has passed through the capacitor to a load and supplying the power to the load. The invention according to claim 21 is claim 19 or 20.
The power supply method of the uninterruptible power supply device according to claim 1, wherein the high frequency power is higher than the audible frequency, that is, higher than about 20 kHz. (3) Erase "Insulate high-frequency power with ..." from page 9, line 16 to page 10, line 1 of the specification.

[Claims]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 1-282249 (32) Priority date Hei 1 (1989) October 30 (33) Country of priority claim Japan (JP) (31) Priority Claim Number Japanese Patent Application No. 1-328062 (32) Priority Date 1 (1989) December 18 (33) Country of priority claim Japan (JP)

Claims (7)

[Claims] 1. An uninterruptible power supply device that supplies power to a load through an insulation circuit to a high-frequency switching power supply circuit that outputs high-frequency power based on power from an input power supply. An uninterruptible power supply characterized by the above. 2. A first frequency conversion circuit that outputs high frequency power in response to an input power supply, an insulation circuit connected to the output of the first frequency conversion circuit, and a connection to the output of the insulation circuit. In the uninterruptible power supply device including a second frequency conversion circuit that outputs alternating-current power, the uninterruptible power supply device is characterized in that the insulating circuit is composed of a capacitor. 3. An uninterruptible power supply, comprising: a first frequency conversion circuit that frequency-converts electric power from a power supply and outputs high-frequency power; and a first frequency conversion circuit connected to the output of the first frequency conversion circuit. A second frequency conversion circuit for frequency-converting the high frequency power output from the frequency conversion circuit to supply power to a load; an output of the first frequency conversion circuit and an input of the second frequency conversion circuit; It is characterized in that it includes an insulating circuit connected between the output terminals of the first frequency converting circuit and the input of the second frequency converting circuit, and forming an insulating barrier. 4. A first frequency conversion circuit that switches electric power from an input power supply to output electric power of a frequency higher than that of the input power supply; and a first frequency conversion circuit connected to an output of the first frequency conversion circuit, An uninterruptible power supply device comprising: a capacitor through which electric power passes; and a second frequency conversion circuit that frequency-converts the high-frequency electric power that has passed through the capacitor to supply electric power to a load. 5. An uninterruptible power supply, comprising: a first frequency conversion circuit that frequency-converts electric power from a power supply to output high-frequency power; and a first frequency conversion circuit that is connected to an output of the first frequency conversion circuit. A second frequency conversion circuit for converting the frequency of the high frequency power output from the first frequency conversion circuit to supply power to a load; and an output of the first frequency conversion circuit and a second frequency conversion circuit. It is characterized in that it includes a capacitor which is connected to an input and which passes the high frequency power but blocks the DC power. 6. An uninterruptible power supply device, characterized in that power from an input power source is converted into high frequency alternating current power, and the high frequency alternating current power is passed through an insulating barrier through an electric field. Insulation method. 7. A step of frequency-converting electric power from an input power source into high-frequency electric power, passing the high-frequency electric power through a capacitor, and further converting the high-frequency electric power passing through the capacitor into a frequency. A method for supplying power to an uninterruptible power supply, comprising a step of converting and supplying power to a load.