JPH04344179A - Ac power source insulating method, switching power supply and insulating method - Google Patents

Abstract

PURPOSE:To suppress the generation of electrical obstructive noise produced when switching is made by insulating a load from an AC source by using capacitors and, at the same time, providing a circuit which by-passes a low-frequency current. CONSTITUTION:An insulation circuit 20 is connected between an AC source 1 and load circuit 4. A by-pass circuit 3 is connected in parallel with the current source 1. By constituting an insulating barrier 45 of the capacitors C1 and C2 of the circuit 20, the circuit 4 is electrically floated against the current source 1 so that the circuit 4 can be capacitance-coupled with the current source 1. Since the capacitors C1 and C2 show high impedances against a low frequency, extremely high voltages are generated in the capacitors C1 and C2 and the capacitors C1 and C2 are destroyed when the current source 1 contains a DC component or low-frequency current component. In order to prevent the destruction of the capacitors C1 and C2, a current passage J for a DC or low-frequency current is provided. Therefore, no obstructive noise is generated in the power supply line.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for insulating an alternating current source, a switching power supply, and a method for insulating the same. More specifically, the present invention relates to a method of insulating the output of an alternating current source, a switching power supply device having an isolation circuit on the output power line of a switching power supply circuit that outputs alternating current power based on magnetic energy, and a method of insulating the same. .

0002

2. Description of the Related Art FIG. 2 is a power supply circuit diagram showing an example of a conventional power supply circuit. Referring to FIG. 2, an insulating circuit 2 is used between the alternating current source 1 and the load circuit 4 to configure an insulating barrier 44 that electrically suspends the load circuit 4 relative to the alternating current source 1. . The alternating current from the alternating current source 1 input to the primary side terminals A, B of the insulation circuit 2 is transferred to the secondary side terminals C, D via the magnetic flux passing through the insulation barrier 44 of the insulation transformer T.
The power is transmitted to the load circuit 4, and the power is supplied to the load circuit 4. In other words, the primary side terminals A, B and the secondary side terminals C, D are connected to the insulation barrier 4.
4, and power is transmitted using the magnetic field inside the isolation transformer T passing through the insulation barrier 44 as a medium. In FIG. 2, when the current value of the alternating current source changes rapidly, an excessive surge voltage is inevitably generated from the leakage inductance of the isolation transformer T.

FIG. 3 is an electrical circuit diagram showing an example of a conventional switching power supply device. Referring to Figure 3, DC power supply E
DC current is supplied to the switching power supply circuit 5 via the DC reactor LDC. The switching power supply circuit 5 consists of four full-bridge connected switching elements S1, S2, S3, and S4, and uses a gate turn-off thyristor (GTO), which is a self-extinguishing switching element, as the switching element. A gate signal is applied to the gate of each of the switching elements S1 to S4 from a control circuit (not shown). In response to the gate signal, the switching elements S1 to S4 perform a switching operation, and are placed in a conductive (on) state or a non-conductive (non-conductive) state.
off) state. By the switching operation of each switching element, the switching power supply circuit 5 converts the DC power from the DC power supply E into AC power based on the magnetic energy stored in the DC reactor LDC. The AC power is output from AC output points A1 and B1 of the switching power supply circuit 5. AC output point A1 of switching power supply circuit 5
, B1 and secondary side terminals C and D of the insulation circuit 2 are connected via insulation transformers T, respectively. The insulation transformer T forms an insulation barrier 44 between the AC output points A1, B1 of the switching power supply circuit 5 and the secondary side terminals C, D of the insulation circuit 2. This insulating barrier 44 electrically floats the secondary terminals C and D with respect to the AC output points A1 and B1. In other words, the switching power supply circuit 5 outputs AC power from the magnetic energy stored in the DC reactor LDC on the input side.
The secondary side terminals C and D are electrically insulated from the AC output points A1 and B1. A frequency conversion circuit 7 and a load circuit 4 are connected to the secondary side terminals C and D as loads.

In the switching power supply shown in FIG. 3, the current flowing through the DC reactor LDC is proportional to the magnetic energy stored in the DC reactor LDC. Due to the continuity of energy, it is impossible for this magnetic energy to change instantaneously and discontinuously. That is, the current flowing through the DC reactor LDC cannot change intermittently. Similarly, the current flowing through the leakage inductance of the isolation transformer T cannot change intermittently. Therefore, when the current flowing through the DC reactor LDC is instantaneously forced into the isolation transformer T by the switching operation of the switching power supply circuit 5, an excessive surge voltage is generated due to the leakage inductance of the isolation transformer T.

FIG. 4 is a timing diagram for explaining the operation of the switching power supply shown in FIG. 3. Next, the operation of the switching power supply device shown in FIG. 3 will be described with reference to FIG. 4. First, the gate signals of switching elements S1 and S4 are turned on as shown in FIG. 4(a), and the gate signals of switching elements S2 and S3 are turned off as shown in FIG. 4(b). Switching elements S1, S4
is on (conducting state), switching elements S2, S
3 is off (non-conducting), AC output point A1
and B1, there is a DC reactor L shown in Fig. 4(c).
A DC current iLDC flows out from the AC output point A1, passes through the primary side terminal A of the insulation circuit 2 and the primary winding of the insulation transformer T, and flows from the primary side terminal B toward the AC output point B1. At that time, the secondary side terminal C of the insulation circuit 2 is
A current iC as shown in (d) flows, and the DC reactor L
Since the DC magnetic energy is absorbed by the load circuit 4, the current iLDC flowing through the DC reactor LDC decreases. Then, in order to replenish the decreased magnetic energy of the DC reactor LDC from the DC power supply E, the gate signals of all the switching elements S1 to S4 are turned on. A period in which the gate signals of all switching elements S1 to S4 are turned on, that is, a short-circuit period is provided, and the DC reactor LDC is
stores energy. After the short circuit period ends, that is, after the magnetic energy replenishment of the DC reactor LDC is completed,
The gate signals of switching elements S1 and S4 are turned off, and the gate signals of switching elements S2 and S3 are turned on. Then, in response to the gate signal, the switching element S
1. When S4 is forced to turn off, an excessive surge voltage is generated from the leakage inductance of the isolation transformer T. This is because the switching elements S1 and S4 are forcibly extinguished (turned off), and the DC reactor LD
The current flowing through C is forced to flow into the isolation transformer T,
This occurs because the current flowing through the leakage inductance of the isolation transformer T must change rapidly. Switching elements S1 and S4 are off, switching element S2
, S3 are on, the current in the DC reactor LDC flows from the AC output point B1 toward the primary terminal B,
AC output point A from primary side terminal A via isolation transformer T
Flows into 1. Thereafter, a short circuit period is provided again, and the reduced magnetic energy of the DC reactor LDC is replenished. By repeating the above series of operations, the DC current flowing through the DC reactor LDC is converted into an AC current and output from the AC output points A1 and B1. The output alternating current is transmitted to the secondary side of the isolation transformer T via the magnetic field passing through the insulation barrier 44 of the isolation transformer T, and power is supplied to the load.

[0006]

[Problem to be Solved by the Invention] As mentioned above, when using an AC power source whose current value is forcibly changed rapidly, when the current value of the AC current source changes rapidly, the problem arises due to leakage inductance of the isolation transformer. Excessive surge voltage occurs. Due to such excessive surge voltages, illegal electromagnetic waves are radiated and scattered into the atmosphere as radiation noise, and a large amount of interference noise is generated in the power lines as conduction noise, creating a major problem in the electromagnetic environment. Furthermore, the excessive surge voltage causes serious problems such as immediate damage to the switching elements of the switching power supply circuit due to overvoltage resistance. Therefore, an object of the present invention is to provide an insulating method for an alternating current source, a switching power supply device, and a method for insulating an alternating current source, which can prevent the generation of excessive surge voltage, substantially eliminate the generation of large disturbance noise, and prevent damage to switching elements. and an insulation method thereof.

[0007]

[Means for Solving the Problem] The invention according to claim 1 is an insulating method for an AC power source that insulates between an AC current source and a load circuit, which comprises installing a capacitor between the AC current source and the load circuit. 1. A method for insulating an alternating current power source, characterized in that the capacitor is connected and insulated by an insulating barrier of the capacitor, and a current path is provided in parallel with the alternating current source.

The invention according to claim 2 includes the frequency conversion circuit of the invention according to claim 1, which is connected between the capacitor and the load and converts the frequency of alternating current or alternating current power from an alternating current source. , The method of insulating an AC power supply according to claim 1.

The invention according to claim 3 provides a switching power supply device comprising a switching power supply circuit that converts power from a power supply using magnetic energy, and an insulation barrier between the output of the switching power supply circuit and a load. , a switching power supply device comprising an insulation barrier made of a capacitor and a current path through which a current flows in parallel on the output side of a switching power supply circuit.

The invention according to claim 4 is a switching power supply device including a cycloconverter that converts power from an AC power source through magnetic energy and an insulation barrier on the output side of the cycloconverter, in which the insulation barrier is a capacitor. 1. A switching power supply device comprising: a current path through which a current flows in parallel with an insulating barrier;

The invention according to claim 5 provides a switching power supply circuit that converts power from a power supply using magnetic energy, a frequency conversion circuit that frequency converts the output of the switching power supply circuit, and a switching power supply circuit and a frequency conversion circuit. 1. A switching power supply device comprising an insulation barrier between the insulation barrier and the insulation barrier, the insulation barrier comprising a capacitor and a current path through which current flows in parallel to the insulation barrier.

[0012] The invention according to claim 6 includes the steps of switching the power from the power supply via magnetic energy to convert the frequency into power having a higher frequency than the power from the power supply, and bypassing the low frequency current; , a method of insulating switching power supplies consisting of the steps of passing high-frequency power through an insulating barrier using an electric field as a medium.

[0013] The invention according to claim 7 includes the steps of converting power from a power supply using magnetic energy into power having a higher frequency than the power from the power supply, bypassing the low frequency current, and A switching power supply device comprising a step of passing high-frequency power through an insulation barrier made of a capacitor, and a step of switching and converting the high-frequency power that has passed through the insulation barrier into low-frequency power. insulation method.

[0014] The invention according to claim 8 comprises a step of converting power from a power supply using magnetic energy into power having a higher frequency than the power from the power supply, and converting the high frequency power using a capacitor. A switching power supply device comprising a step of passing the electric charge through an insulation barrier, a step of discharging the charge of a capacitor, and a step of switching the high frequency power that has passed through the insulation barrier and converting the frequency into low frequency power. Insulation method.

The invention according to claim 9 is an insulation method for a switching power supply device according to claims 7 and 8, further comprising a step of suppressing a common mode current passing through an insulation barrier. Insulation method.

[0016] The invention according to claim 10 is based on claims 7 and 8.
, 9, which is an insulation method for a switching power supply device, characterized in that the high frequency power is power at an audio frequency or higher.

[0017] The invention according to claim 11 is based on claims 9 and 1.
1. An insulation method for a switching power supply device, which is a method for insulating a switching power supply device and is characterized in that common mode current is suppressed using a common mode choke.

[0018] The invention according to claim 12 is based on claims 9 and 1.
1. An insulation method for a switching power supply device, which is an insulation method subordinate to zero, and characterized in that common mode current is suppressed using a reactor.

[0019]

[Operation] According to the present invention, an insulating circuit that electrically floats between a load and a switching power supply circuit that converts power using an alternating current source or magnetic energy is configured with a capacitor, and an insulating transformer is used. The leakage inductance of the isolation transformer that occurs when constructing an isolation circuit is substantially eliminated. Therefore, in principle, it is possible to construct an isolation circuit in which there is no leakage inductance of the isolation transformer.

Furthermore, by providing a bypass circuit,
The generation of high voltage due to low frequency current flowing through the insulation capacitor is effectively suppressed or reduced.

[0021]

[Embodiment] It can be said that alternating current sources have come to be recognized as a real thing due to the remarkable development of power semiconductor engineering in recent years. A clear example of this is that although electrical symbols for AC voltage sources have existed for a long time, the electrical symbols for AC current sources have not yet been specified. This alternating current source can now be easily realized using power semiconductors. For example, current source inverters can be said to be a great example of this. Most actual alternating current sources utilize energy stored in direct current or alternating current reactors, that is, magnetic energy, to form an apparent alternating current source. This can be easily understood if it is considered that the voltage source is constructed in an apparently pseudo manner using energy stored in a capacitor, that is, electrostatic energy. In an alternating current source configured in this manner, the current waveform flowing from the alternating current source is a square wave, and the current value changes rapidly or intermittently. Therefore, in the embodiments described below, embodiments of the present invention will be explained by taking as an example a basic AC current source constituted by a power semiconductor element and a reactor.

FIG. 1 is an electrical circuit diagram showing a first embodiment of the present invention. Referring to FIG. 1, an insulation circuit 20 is connected between alternating current source 1 and load circuit 4. As shown in FIG. AC current source 1
A bypass circuit 3 is connected in parallel. The bypass circuit 3 consists of a current path J. Primary side terminal A of the insulation circuit 20
, B are connected to an alternating current source 1. The insulating circuit 20 has primary side terminals A, B and secondary side terminals C, D connected via capacitors C1, C2, respectively. A load circuit 4 is connected to secondary side terminals C and D of the insulation circuit 20. An insulating barrier 45 is constituted by the capacitors C1 and C2 of the insulating circuit 20, and the load circuit 4 is electrically suspended by this insulating barrier 45 with respect to the alternating current source 1. Insulated circuit 2
0 primary side terminals A, B and secondary side terminals C, D are capacitively coupled through an insulating barrier 45, and energy transfer between the AC current source 1 side and the load circuit 4 side passes through the insulating barrier 45. This is carried out using the electric field inside the capacitors C1 and C2 as a medium. Here, the function of the bypass circuit 3 will be explained. Capacitors C1 and C2 exhibit high impedance for low frequencies. In particular, it shows infinite impedance to direct current. Therefore, when the AC current source 1 includes a DC current component or a low frequency current component, an extremely high voltage is generated across the capacitors C1 and C2. As a result, there is a risk that the capacitors C1 and C2 will be destroyed. In order to avoid this, a current path J through which direct current or low frequency current flows is provided.

FIG. 5 is an electrical circuit diagram showing a second embodiment of the invention. In the embodiment shown in FIG. 5, the DC current source 1
1 and a switching power supply circuit 5 constitute an alternating current source. Each switching element S1, S2, S3, and S4 of the switching power supply circuit 5 is a gate turn-off thyristor (self-extinguishing switching element).
GTO). This switching power supply circuit 5 outputs alternating current power by turning on and off switching elements S1, S2, S3, and S4 when a direct current is input from a direct current source 11, and is widely known as a so-called current source inverter. This is a power supply circuit called The switching power supply circuit 5 includes switching elements S1 and S4.
is on and switching elements S2 and S3 are off,
An operation is performed in which a state in which switching elements S1 and S4 are off and switching elements S2 and S3 are on is alternately repeated for an equal period of time, a so-called inverter operation that converts direct current into alternating current. By the inverter operation of the switching power supply circuit 5, the direct current from the direct current power supply 11 is converted into alternating current,
It is input to the isolation circuit 20. The frequency of the alternating current that has passed through the insulating circuit 20 is converted into direct current by the frequency conversion circuit 7, and the DC current is applied to the load circuit 4. Here, the bypass circuit 3 connected to the output side of the switching power supply circuit 5
Explain the functions of. Capacitors C1 and C2 exhibit high impedance for low frequencies. In particular, it shows infinite impedance to direct current. Therefore, when the switching power supply circuit 5 outputs a DC current component or a low frequency current component, an unnecessary high voltage is generated on the capacitor C1 due to this DC current component or low frequency current component.
, C2. As a result, there is a risk that the switching elements constituting the switching power supply circuit 5 will be destroyed. In order to avoid this, a current path J through which direct current or low frequency current flows is provided. In other words, since there is a current path J, a DC current component or a low frequency current component flows through this current path, so capacitors C1 and C2
The DC voltage component or low frequency voltage component generated in this case is effectively reduced.

FIG. 6 is an electrical circuit diagram showing a third embodiment of the present invention. The embodiment shown in FIG. 6 is constructed using a controllable DC voltage source 12 and a DC reactor LDC in place of the DC current source 11 of the embodiment shown in FIG. In this embodiment, the DC voltage source 12 is set so that the DC current flowing through the DC reactor LDC follows a desired value.
By controlling the switching power supply circuit 5, the DC current supplied to the switching power supply circuit 5 can be varied. In this third embodiment, the power of the DC voltage source 12 is input to the switching power supply circuit 5 via the magnetic energy of the DC reactor LDC. The switching power supply circuit 5 converts power using magnetic energy stored in a DC reactor LDC and outputs AC power. The output AC power is transmitted through the insulating barrier 45 using an electric field as a medium, and is supplied to the load side. Here, the bypass circuit 3 connected to the output side of the switching power supply circuit 5 performs the same function as the example shown in FIG.

FIG. 7 is an electrical circuit diagram showing a fourth embodiment of the present invention. The embodiment shown in FIG. 7 uses an AC voltage source 13 and a converter 6 in place of the controllable DC voltage source 12 shown in FIG. The converter 6 includes switching elements Q1, Q2, which are made of thyristors, for example.
Q3 and Q4 are connected in a full bridge. Here, by controlling the phase of the converter 6, a variable DC voltage is outputted from the converter 6 based on the AC voltage supplied from the AC voltage source 13. Then, by feeding back the DC current flowing to the DC reactor LDC and controlling the phase of the converter 6, the DC reactor LD
Feedback control can be performed so that the DC current flowing through C follows a desired value, and the DC reactor LDC apparently functions as a DC current source. A DC current from the DC current source configured in this manner is applied to the switching power supply circuit 5 and converted into an AC current, and the insulation circuit 20
It becomes a pseudo alternating current source. In this fourth embodiment, the power of the AC voltage source 13 is input to the switching power supply circuit 5 via the magnetic energy of the DC reactor LDC. The switching power supply circuit 5 converts power using magnetic energy stored in a DC reactor LDC and outputs AC power. The output AC power is transmitted through the insulating barrier 45 using an electric field as a medium, and is supplied to the load side. Here, the bypass circuit 3 connected to the output side of the switching power supply circuit 5 performs the same function as the example shown in FIG.

FIG. 8 is an electrical circuit diagram showing a fifth embodiment of the present invention. Referring to FIG. 8, DC power from DC power supply E is supplied to switching power supply circuit 5 via DC reactor LDC. The switching power supply circuit 5 includes four full-bridge connected switching elements S1, S2,
It consists of S3 and S4, and a gate turn-off thyristor (GTO) is used as the switching element. A gate signal is applied to the gate of each of the switching elements S1 to S4 from a control circuit (not shown), and each of the switching elements S1 to S4 performs a switching operation (on/off operation) in response to each gate signal. By the switching operation of each switching element S1 to S4, the switching power supply circuit 5 converts (frequency converts) the DC power of the DC power supply E through the magnetic energy stored in the DC reactor LDC, and converts the AC power to the AC output point A1. , B1. An insulating circuit 20 is connected between the switching power supply circuit 5 and the load circuit 4. This insulating circuit 20 has primary side terminals A, B and secondary side terminals C, D connected via capacitors C1, C2, respectively. Capacitors C1 and C2 are connected to the AC output point A1 of the switching power supply circuit 5.
, B1 and the secondary side terminals C, D of the insulation circuit 20 constitute an insulation barrier 45. This insulating barrier 45 electrically floats the secondary terminals C and D with respect to the AC output points A1 and B1. The primary side terminals A, B and the secondary side terminals C, D are capacitively coupled through the insulating barrier 45, and the transfer of energy between the AC current source 1 side and the load circuit 4 side is carried out by the capacitor C1 passing through the insulating barrier 45. , C2 using the electric field as a medium. A load circuit 4 is connected to the secondary side terminals C and D via a frequency conversion circuit 7.

Next, the operation of the switching power supply shown in FIG. 8 will be explained. This power supply is the second one in Figure 5.
In addition to the so-called inverter operation that converts direct current to alternating current as explained in the embodiment, the current iLD of the direct current reactor LDC
In order to control C, all switching elements S1,
An operation of turning on the gate signals of S2, S3, and S4, a so-called short circuit operation, is used intermittently. That is, by turning on the gate signals of all switching elements S1, S2, S3, and S4 and short-circuiting the switching power supply circuit 5, the energy sent from the DC power supply E is stored in the DC reactor LDC as magnetic energy. In other words,
The short circuit operation increases the direct current iLDC. After the short circuit operation is completed, the switching power supply circuit 5 shifts to inverter operation, the gate signals of the switching elements S1 and S4 or the switching elements S2 and S3 are turned off, and the magnetic energy of the DC reactor LDC is supplied to the load circuit 4.

FIG. 4 is a timing chart showing the operation of the switching power supply shown in FIG. 8, and the operation of the switching power supply shown in FIG. 8 will be explained in detail with reference to FIG. First, the gate signals of switching elements S1 and S4 are turned on as shown in FIG. 4(a), and the gate signals of switching elements S1 and S4 are turned on as shown in FIG. 4(b).
The gate signals of switching elements S2 and S3 are turned off as shown in FIG. When switching elements S1 and S4 are on (conducting state) and switching elements S2 and S3 are off (non-conducting state), there is a gap between AC output points A1 and B1 as shown in FIG. 4(c). The current iLDC from the DC reactor LDC flows out from the AC output point A1 to the insulation circuit 20.
It passes through the primary side terminal A, the frequency conversion circuit 7, and the load circuit 4, and flows from the primary side terminal B toward the AC output point B1. At that time, the secondary side terminal C of the insulation circuit 20 is connected to the
A current iC as shown in d) flows, and the DC reactor LD
Since the magnetic energy of C is absorbed by the load circuit 4, the current iLDC flowing through the DC reactor LDC decreases. Therefore, in order to replenish the magnetic energy of the DC reactor LDC from the DC power supply, all switching elements S
The gate signals 1 to S4 are turned on, a short-circuit time is provided, and energy is stored in the DC reactor LDC. After the short circuit period ends, that is, after the replenishment of the magnetic energy of the DC reactor LDC is completed, the switching element S is forcibly switched off.
The gate signals of switching elements S1 and S4 are turned off, and the gate signals of switching elements S2 and S3 are turned on. When the switching elements S1 and S4 are off and the switching elements S2 and S3 are on, the current in the DC reactor LDC flows from the AC output point B1 towards the primary side terminal B, via the frequency conversion circuit 7 and the load circuit 4. and flows from the primary side terminal A to the AC output point A1. Thereafter, a short circuit period is provided again, and the reduced magnetic energy of the DC reactor LDC is replenished. By repeating the above-described operation, the DC current flowing through the DC reactor LDC is converted into an AC current, and the AC current is supplied to the load circuit 4, which is output from the AC output points A1 and B1. The insulating barrier 45 constituted by the capacitors C1 and C2 exhibits substantially infinite impedance to direct current. Furthermore, by increasing the switching frequency of the switching power supply circuit 5, the capacitances of the capacitors C1 and C2 can be reduced to some extent. Therefore, capacitors C1 and C2 have a substantially large impedance even for low frequencies near DC.
Since it can have the same characteristics, it can be used as a quasi-isolated circuit even for low frequencies near direct current. Here, the function of the bypass circuit 3 connected to the output side of the switching power supply circuit 5 will be explained. Capacitors C1 and C2 exhibit high impedance for low frequencies. Therefore, when the switching power supply circuit 5 outputs a low frequency current component, an unnecessary high voltage is generated in the capacitors C1 and C2 due to the low frequency current component. As a result, an unnecessary high voltage is generated between the output terminals of the switching power supply circuit 5, and an unnecessary high voltage is applied to the switching elements constituting the switching power supply circuit 5. In order to avoid this, a current path J through which direct current or low frequency current flows is provided. That is, since there is a current path J, a DC current component or a low frequency current component flows through this current path, so that the DC voltage component or low frequency voltage component generated in the capacitors C1 and C2 is effectively suppressed. Thereby, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit 5 is effectively suppressed.

FIG. 9 is an electrical circuit diagram showing a sixth embodiment of the present invention. In this embodiment, a DC voltage source is constructed by a rectifier circuit 61, an AC voltage source 13, and a DC capacitor CDC, and other basic operations are the same as in FIG. In this sixth embodiment, the power of the AC voltage source 13 is temporarily stored as electrostatic energy in the DC capacitor CDC. This stored electrostatic energy is input to the switching power supply circuit 5 via the magnetic energy of the DC reactor LDC. The switching power supply circuit 5 converts power using magnetic energy stored in the DC reactor LDC, and outputs AC power. The output AC power is transmitted through the insulation barrier 45 using an electric field as a medium,
Supplied to the load side. Here, switching power supply circuit 5
The bypass circuit 3 connected to the output side of the circuit performs the same function as the example shown in FIG.

FIG. 10 is an electrical circuit diagram showing a seventh embodiment of the present invention. The embodiment shown in FIG. 10 is obtained by removing the DC capacitor CDC from the embodiment shown in FIG. By omitting the DC capacitor CDC, when the voltage value of the AC voltage source 13 becomes zero, the output voltage of the rectifier circuit 61 also becomes zero, so there is a period in which the DC current of the DC reactor LDC cannot be sufficiently controlled. This has the advantage that the input current waveform and input power factor on the AC voltage source 13 side can be improved.

FIG. 11 is an electrical circuit diagram showing an eighth embodiment of the present invention. The embodiment shown in FIG. 11 is based on the rectifier circuit 61 and switching power supply circuit 5 of the embodiment shown in FIG.
Except for the reactor LDC connected between the AC reactor LAC and the AC voltage source 13, the other basic operations are the same as in FIG. In this eighth embodiment, the electric power from the AC voltage source 13 passes through the magnetic energy of the AC reactor LAC, and then once passes through the rectifier circuit 61.
The DC power is converted into DC power and input to the switching power supply circuit 5. The switching power supply circuit 5 performs power conversion based on the magnetic energy stored in the AC reactor LAC, and outputs AC power. The output AC power is transmitted through the insulating barrier 45 using an electric field as a medium, and is supplied to the load side.

FIG. 12 is an electrical circuit diagram showing a ninth embodiment of the present invention, in which the rectifier circuit 61 and the switching power supply circuit 5 shown in FIG. 11 are combined into one switching power supply circuit 51.
It has been replaced with . Each switching element S1, S2, S3, S4, S5, S of the switching power supply circuit 51
6, S7, S8 are gate turn-off thyristors (GTO
). This switching power supply circuit 51 is a power supply circuit that can directly output input AC power as AC power of another frequency, and is academically called a cycloconverter. In the operation of the embodiment shown in FIG. 12, first, the gate signals of all switching elements S1 to S8 are turned on, and magnetic energy is stored in the AC reactor LAC. Next, switching elements S1, S4,
The magnetic energy of the AC reactor LAC is supplied to the load circuit 4 by turning on the gate signals of S5 and S8 and turning off the gate signals of switching elements S2, S3, S6, and S7. Furthermore, the gate signals of all the switching elements S1 to S8 are turned on, and magnetic energy is stored in the AC reactor LAC. and,
The gate signals of switching elements S2, S3, S6, S7 are turned on, and switching elements S1, S4, S5, S
By turning off the gate signal 8, the magnetic energy of the AC reactor LAC is supplied to the load circuit 4. By repeating the above series of operations, the alternating current flowing through the alternating current reactor LAC is directly converted to an alternating current of another frequency without being converted to direct current, and is output from the cycloconverter 51. In this ninth embodiment, the power from the AC voltage source 13 passes through the magnetic energy of the AC reactor LAC and is directly supplied to the cycloconverter 5.
1 is input. The cycloconverter 51 performs power conversion using the magnetic energy stored in the AC reactor LAC, and outputs AC power. cycloconverter 5
The alternating current power output from the insulating barrier 45 is transmitted through the electric field as a medium, and is supplied to the load side. Here, the function of the bypass circuit 3 connected to the output side of the switching power supply circuit 51 will be explained. Capacitor C1
, C2 exhibit high impedance for low frequencies. Therefore, when the switching power supply circuit 5 outputs a low frequency current component, an unnecessary high voltage is generated in the capacitors C1 and C2 due to the low frequency current component. As a result, an unnecessary high voltage is generated between the output terminals of the switching power supply circuit 51, and an unnecessary high voltage is applied to the switching elements constituting the switching power supply circuit 51. In order to avoid this, a current path J through which direct current or low frequency current flows is provided. In other words, since there is a current path J, a DC current component or a low frequency current component flows through this current path, so the capacitor C1
, C2 are effectively suppressed or reduced. Thereby, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit 51 is effectively suppressed or reduced.

FIG. 13 is an electrical circuit diagram showing a tenth embodiment of the present invention. FIG. 13 is configured similarly to FIG. 8 described above except for the following points. That is, in Figure 13, Figure 8
A power cart M with a built-in freewheeling diode as a switching element in place of the switching elements S1 to S4 shown in
The switching power supply circuit 5F uses extremely high-speed self-extinguishing switching elements Q1 to Q4 made of OSFETs.
It consists of Therefore, instead of capacitors C1 and C2 that constitute the insulation circuit 20 in FIG.
, C2F is used to configure the insulation circuit 20F. The difference between the capacitors C1F and C2F and the capacitors C1 and C2 is that the capacitors C1F and C2F have a capacitance that is about three orders of magnitude smaller than that of the capacitors C1 and C2. Next, the operation in FIG. 13 will be explained. The operation in FIG. 13 is similar to the operation in FIG. 8 except for the following points. That is, the gates of the switching elements Q1 to Q4 constituting the switching power supply circuit 5F of FIG. 13 are turned on and off at a switching frequency of 1 MHz. Therefore, Figure 1
In case 3, the shape of the waveform itself is the same as that of the current iC passing through the secondary terminal C shown in Fig. 4(d), but the repetition frequency is significantly different, and it is a rectangular wave with an extremely high frequency of 1 MHz. The wave becomes an alternating current. Here, a supplementary explanation will be given regarding the functions of capacitors C1F and C2F. The capacitors C1F and C2F have low impedance with respect to the 1 MHz alternating current output from the switching power supply circuit 5F, and the provision of the capacitors C1F and C2F will not cause any problem in terms of power transmission. However, the insulation barrier 45F constituted by the capacitors C1F and C2F not only exhibits zero frequency, that is, infinite impedance to direct current, but also exhibits an infinite impedance to direct current.
or 60Hz), it shows extremely high impedance. Since the impedance value shown by capacitors C1F and C2F is inversely proportional to the frequency, the impedance value at 50Hz is 1MHz/50 for the impedance value at 1MHz.
Hz = 20,000 times higher value. Therefore, leakage of electrical energy as weak as a signal at low frequencies is
It can be virtually ignored as a switching power supply. Therefore, due to the increase in frequency, this isolation circuit can actually be usefully used as an isolation circuit for switching power supplies not only for direct current but also for power frequencies on the order of commercial frequencies. That is, it can be used as an insulating circuit for DC power and commercial power. This has been achieved by increasing the frequency of the switching power supply, and if the output frequency of the switching power supply circuit is not much higher than the commercial power supply frequency, for example, 500H
At frequencies below the audible frequency of about Difficult to use as a circuit. Next, the function of the bypass circuit 3 connected to the output side of the switching power supply circuit 5F will be explained here. Capacitors C1F and C2F exhibit high impedance for low frequencies. Therefore, when the switching power supply circuit 5F outputs a low frequency current component, an unnecessary high voltage is generated in the capacitors C1F and C2F due to the low frequency current component. As a result, an unnecessary high voltage is generated between the output terminals of the switching power supply circuit 5F, and an unnecessary high voltage is applied to the switching elements constituting the switching power supply circuit 5F. In order to avoid this, a current path J through which direct current or low frequency current flows is provided. In other words, since there is a current path J, a direct current component or a low frequency current component flows through this current path, so capacitors C1F and C2
The DC voltage component or low frequency voltage component generated at F is effectively suppressed. Thereby, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit 5F is effectively suppressed.

FIG. 14 is an electrical circuit diagram showing an eleventh embodiment of the present invention. The embodiment shown in FIG.
In place of the DC power supply E and reactor LDC of the embodiment shown in 3, an AC voltage source 13 and AC reactor LAC are used,
It is connected to the switching power supply circuit 5F via a rectifier circuit 61, and the other basic configuration is the same as that in FIG. In the eleventh embodiment, the power from the AC voltage source 13 passes through the magnetic energy of the AC reactor LAC, is once converted into DC power by the rectifier circuit 61, and is input to the switching power supply circuit 5F. The switching power supply circuit 5F performs power conversion based on the magnetic energy stored in the AC reactor LAC, and outputs AC power. The output AC power is transmitted through the insulating barrier 45F using an electric field as a medium, and is supplied to the load side.

FIG. 15 is an electric circuit showing a twelfth embodiment of the present invention, in which an inductive load circuit 41 is used as the load circuit. Referring to FIG. 15, an insulation circuit 22 is connected between alternating current source 1 and inductive load circuit 41. The insulation circuit 22 includes a capacitor C1 connected in series between terminals A and C, a capacitor C2 connected in series between terminals B and D, and a capacitor C3 connected between terminals A and D. , and a capacitor C4 connected between terminals B and C. Capacitors C3 and C4 function as filters. That is, as a result of the AC current from the AC current source 1 being charged to the capacitors C3 and C4, the capacitors C3 and C4 become pseudo AC voltage sources, and this AC voltage is applied to the inductive load circuit 41 via C1 and C2. Given. In this way, since the capacitors C3 and C4 act as filters, no surge voltage is generated even if the inductive load circuit 41 is connected.

In the example shown in FIG. 16, capacitor C3 is connected between terminals A and B, and capacitor C4 is connected between terminals C and D.
Similarly to the example shown in FIG. 15, the capacitors C3 and C4 act as a filter.

FIG. 17 shows the insulation circuit 22 shown in FIG.
A frequency conversion circuit 7 is connected between the inductive load circuit 41 and the inductive load circuit 4, and the frequency conversion circuit 7 converts the AC power that has passed through the insulation circuit 22 into DC power.
1.

FIG. 18 shows the insulation circuit 22 shown in FIG.
A frequency conversion circuit 7 is connected between the insulating circuit 221 and the inductive load circuit 41, and the frequency conversion circuit 7 converts the AC power that has passed through the insulation circuit 221 into DC power and supplies it to the inductive load circuit 41. .

FIG. 19 is an electrical circuit diagram showing a 16th embodiment of the present invention. The embodiment shown in FIG. 19 is as shown in FIG.
The capacitor C4 is removed from the insulation circuit 22 shown in FIG. As in FIG. 15, since the capacitor C3 functions as a filter, no surge voltage is generated even if the inductive load circuit 41 is connected.

FIG. 20 is an electrical circuit diagram showing a seventeenth embodiment of the present invention. The embodiment shown in FIG. 20 is as shown in FIG.
The capacitor C4 is removed from the insulation circuit 221 shown in FIG. As in FIG. 16, since the capacitor C3 functions as a filter, no surge voltage is generated even if the inductive load circuit 41 is connected.

FIG. 21 is an electrical circuit diagram showing an 18th embodiment of the present invention. In the embodiment shown in FIG. 21, the insulation circuit 20 shown in FIG. 5 is replaced with the insulation circuit 231 shown in FIG. is the same as As in FIG. 20, capacitor C3 acts as a filter. Therefore, the voltage between the terminals A and B of the insulating circuit 231 does not change intermittently, and the generation of noise is effectively suppressed.

FIG. 22 is an electrical circuit diagram showing a nineteenth embodiment of the present invention. The embodiment shown in FIG. 22 replaces the insulation circuit 20 and load circuit 4 shown in FIG. 8 with the insulation circuit 221 and inductive load circuit 41 shown in FIG. Similarly, capacitors C3 and C4 act as filters. Therefore, the voltage between the terminals A and B of the insulating circuit 231 does not change intermittently, and the generation of noise is effectively suppressed. Furthermore, even if the inductive load circuit 41 is connected as a load, no surge voltage is generated.

FIG. 23 is an electrical circuit diagram showing a twentieth embodiment of the present invention. In the embodiment shown in FIG. 23, the current path J of the bypass circuit 3 shown in FIG. 8 is constructed by a bypass circuit 31 consisting of a current path using an inductance. The other main circuit configurations are the same as in FIG. Furthermore, the switching operation of the switching power supply circuit 5 is shown in FIG.
This is basically the same as the embodiment shown in . Here, the bypass circuit 3 connected to the output side of the switching power supply circuit 5
Function 1 will be explained. Capacitors C1 and C2 exhibit high impedance for low frequencies. Therefore, when the switching power supply circuit 5 outputs a low frequency current component, an unnecessary high voltage is generated in the capacitors C1 and C2 due to the low frequency current component. As a result, an unnecessary high voltage is generated between the output terminals of the switching power supply circuit 5, and an unnecessary high voltage is applied to the switching elements constituting the switching power supply circuit 5. To avoid this, a bypass circuit 31 is provided. That is, since the bypass circuit 31 is provided, a direct current component or a low frequency current component flows through the current path of the inductance of the bypass circuit 31, so that the capacitors C1 and C2
DC voltage components or low frequency voltage components generated in As a result, the switching power supply circuit 5
Application of unnecessary high voltage to the switching elements constituting the switch is effectively suppressed.

FIG. 24 is an electric circuit diagram showing a twenty-first embodiment of the present invention. The embodiment shown in FIG. 24 has a bypass circuit 3 consisting of switching elements connected in antiparallel in place of the inductance of the bypass circuit 31 shown in FIG.
3 was used. The other main circuit configurations are the same as in FIG. 23. Furthermore, the switching operation of the switching power supply circuit 5 is basically the same as the embodiment shown in FIG. Here, the function of the bypass circuit 33 connected to the output side of the switching power supply circuit 5 will be explained. Capacitors C1 and C2 exhibit high impedance for low frequencies. Therefore, when the switching power supply circuit 5 outputs a low frequency current component, an unnecessary high voltage is generated in the capacitors C1 and C2 due to the low frequency current component. As a result, an unnecessary high voltage is generated between the output terminals of the switching power supply circuit 5, and an unnecessary high voltage is applied to the switching elements constituting the switching power supply circuit 5. To avoid this, a bypass circuit 33 is provided. That is, by controlling the gate signal of each switching element of the bypass circuit 33 and causing the DC current component or low frequency current component output from the switching power supply circuit 5 to flow through the current path made up of the switching elements of the bypass circuit 33, the capacitor C1 , C2 are effectively suppressed. Thereby, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit 5 is effectively suppressed.

FIG. 25 is an electrical circuit diagram showing a twenty-second embodiment of the present invention. In the embodiment shown in FIG.
In place of the installation location of the bypass circuit 3 shown in 1, a current path J is provided between the power lines between the insulation circuit 20 and the frequency conversion circuit 7. The other main circuit configurations are the same as in FIG. Furthermore, the switching operation of the switching power supply circuit 5 is basically the same as the embodiment shown in FIG. Here, the function of the bypass circuit 3 provided between the isolation circuit 20 and the frequency conversion circuit 7 will be explained. Capacitors C1 and C2 exhibit high impedance for low frequencies. Therefore, when the switching power supply circuit 5 outputs a low frequency current component, an unnecessary high voltage is generated in the capacitors C1 and C2 due to the low frequency current component. As a result, an unnecessary high voltage is generated between the output terminals of the switching power supply circuit 5, and an unnecessary high voltage is applied to the switching elements constituting the switching power supply circuit 5. To avoid this, a bypass circuit 3 is provided. That is, capacitors C1, C
The charges stored in the switching power supply circuit 2 are discharged through the bypass circuit 3 when the gate signals of all switching elements of the switching power supply circuit 5 are in the on state. That is, the current path J of the bypass circuit 3 constitutes a current path for discharging the charges of the capacitors C1 and C2. Therefore, the DC voltage component or low frequency voltage component generated in the capacitors C1 and C2 is effectively suppressed. Thereby, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit 5 is effectively suppressed.

FIG. 26 is an electrical circuit diagram showing a twenty-third embodiment of the present invention. The embodiment shown in FIG. 26 is as shown in FIG.
The current path J of the bypass circuit 3 shown in FIG. 1 is constructed using an inductance. The other main circuit configurations are the same as in FIG. 25. Here, the role of the bypass circuit 31 comprised of an inductance provided in parallel to the output stage of the isolation circuit 20 will be explained. The bypass circuit 31 is basically unnecessary if the output current of the switching power supply circuit 5 has no low frequency current or direct current component. However, when a low frequency current component or a direct current component exists in the output current of the switching power supply circuit 5, the bypass circuit 33 plays an important role. When a low frequency current component or a direct current component occurs in the output current of the switching power supply circuit 5, charge is gradually stored in the capacitors C1 and C2. This gradually accumulated charge generates a large voltage across the capacitors C1 and C2. However, since the bypass circuit 31 is also used in the output stage of the insulating circuit 20, during the period when the gate signal of each switching element of the switching power supply circuit 5 is in the on state, the charges in the capacitors C1 and C2 are transferred to the bypass circuit 31. Discharged via inductance. That is, the switching elements S9 and S10 of the bypass circuit 31 constitute a current path for discharging the charges of the capacitors C1 and C2. Therefore, the DC voltage component or low frequency voltage component generated in the capacitors C1 and C2 is effectively suppressed. Therefore, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit 5 is suppressed.

FIG. 27 is an electrical circuit diagram showing a twenty-fourth embodiment of the present invention. The embodiment shown in FIG. 27 is as shown in FIG.
The current path J of the bypass circuit 3 shown in FIG. 1 is constructed using switching elements S9 and S10 that are connected in antiparallel to each other. The other main circuit configurations are the same as in FIG. 25. Furthermore, the switching operation of the switching power supply circuit 5 is basically the same as the embodiment shown in FIG.

FIG. 28 is a timing diagram for explaining the operation of the bypass circuit 33 of the switching power supply shown in FIG. 27. FIG. 4(a) shows switching elements S1, S
FIG. 4(b) shows the gate signals of switching elements S2 and S3, and FIG. 4(c) shows the gate signals of switching elements S9 and S10 of the bypass circuit 33. Switching elements S9, S of bypass circuit 33
The gate signal No. 10 is turned on when the gate signals of the switching elements S1, S2, S3, and S4 of the switching power supply circuit 5 are on. Here, with reference to FIG. 28, the role of the bypass circuit 33 comprised of switching elements S9 and S10 provided in parallel at the output stage of the isolation circuit 20 of FIG. 27 will be explained. Bypass circuit 33
is basically unnecessary if the output current of the switching power supply circuit 5 has no low frequency current or direct current component. However, when a low frequency current component or a direct current component exists in the output current of the switching power supply circuit 5, the bypass circuit 33 plays an important role. When a low frequency current component or a direct current component occurs in the output current of the switching power supply circuit 5, charge is gradually stored in the capacitors C1 and C2. This gradually accumulated charge generates a large voltage across the capacitors C1 and C2. However, since the bypass circuit 33 is also used in the output stage of the isolation circuit 20, during the period when the gate signal of each switching element of the switching power supply circuit 5 is in the on state,
The charges in the capacitors C1 and C2 are discharged via the switching element S9 or the switching element S10 of the bypass circuit 33. That is, the switching elements S9 and S10 of the bypass circuit 33 constitute a current path for discharging the charges of the capacitors C1 and C2. Therefore, the DC voltage component or low frequency voltage component generated in the capacitors C1 and C2 is effectively suppressed. Therefore, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit 5 is suppressed.

FIG. 29 is an electrical circuit diagram showing a twenty-fifth embodiment of the present invention. Referring to FIG. 29, DC power supply E, switching power supply circuit 5, insulation circuit 20, load circuit 4, and frequency conversion circuit 7 are constructed in the same manner as in FIG. 8 described above. 29 shows a filter circuit F in addition to the reactor LDC between the DC power supply E and the switching power supply circuit 5 shown in FIG.
The DC power supply E and the switching power supply circuit 5 are connected through the power supply. There are no other differences between FIG. 29 and FIG. Furthermore, the operation of the switching power supply circuit 5 is shown in FIG.
Since the explanation is redundant, it will be omitted. Filter circuit F connects terminals TA, TB and terminals TC, TD to reactor L.
They are connected via DC1 and LDC2, and the input terminals TA and TB of the filter circuit F and the output terminals TC and TD are cut off in terms of high frequency by the reactors LDC1 and LDC2. Therefore, the input side and the output side of the switching power supply device are cut off in terms of high frequency by this filter circuit F. Here, the role of the filter circuit F will be explained in detail. Filter circuit F is basically unnecessary when the impedance between the ground on the input power supply side and the ground on the output load side is infinite, that is, when the input and output grounds are completely electrically independent. . However, for example, if the impedance between the input and output grounds is zero and the filter circuit F is not provided, a steep impulsive common mode current may flow through the insulation circuit 20 due to the switching operation of the switching power supply circuit 5. and flows through the ground between the input and output. As a result, the amount of charge in the capacitor that forms the insulation barrier changes rapidly. Then, an excessive impulse current flows through the switching elements constituting the switching power supply circuit 5, causing destruction of the switching elements. However, by providing the filter circuit F, this problem can be solved. That is, if the inductance values of the reactors LDC1 and LDC2 constituting the filter circuit F are high impedances with respect to the switching frequency of the switching power supply circuit 5, the switching of the switching power supply circuit 5 causes the isolation circuit 20
The impulse common mode current that flows between the input and output grounds via the reactor L that constitutes the filter circuit F
It is effectively suppressed by DC1 and LDC2. Therefore, the filter circuit F suppresses the steep impulse-like common mode current, prevents the voltages of the capacitors C1 and C2 from fluctuating rapidly, and stabilizes the voltage of the capacitors forming the insulation barrier 45. In other words, the reactors LDC1 and LDC2 of the filter circuit F cut off the input power source E and the load 4 at high frequency, and the filter circuit F effectively suppresses the common mode current flowing between the input and output of the switching power supply. Ru.

FIG. 30 shows a twenty-sixth embodiment of the present invention, in which the reactor LDC shown in FIG. 29 is removed. In FIG. 29, the power of the DC power supply E is input to the switching power supply circuit 5 via the magnetic energy of the reactors LDC, LDC1, and LDC2, but in FIG. , the magnetic energy of the LDC 2 is input to the switching power supply circuit 5. The switching power supply circuit 5 converts power using the magnetic energy stored in the reactors LDC1 and LDC2, and outputs AC power. Also, similar to FIG. 29, the reactor L of the filter circuit F
The input power source E and the load circuit 4 are cut off at high frequency by the DC1 and LDC2, and the filter circuit F prevents impulse current from passing between the input and output of the switching power supply device. As a result, capacitors C1 and C2
The voltage of the capacitors C1 and C2 forming the insulating barrier 45 is stabilized without sudden fluctuations.

FIG. 31 is an electrical circuit diagram showing a twenty-seventh embodiment of the present invention. The embodiment shown in FIG. 31 is as shown in FIG.
The filter circuit F shown in FIG. 1 is replaced with a filter circuit FC constituted by a common mode choke LC, and there is no other difference in the configuration. Further, since the operation of the switching power supply circuit 5 is the same as that in FIG. 8, a description thereof will be omitted. This filter circuit FC connects terminals TA and TC via one winding W1 of common mode choke LC, and connects terminals TB and TD to common mode choke L.
The input terminals TA, TB and the output terminals TC, T of the filter circuit FC are connected through the other winding W2 of the filter circuit FC.
D is blocked in a common mode manner by a common mode choke LC. Therefore, the input side and output side of the switching power supply device are cut off in common mode by this filter circuit FC. Next, the role of the filter circuit FC will be explained in detail. The filter circuit FC is basically unnecessary when the impedance between the ground on the input power supply side and the ground on the output load side is infinite, that is, when the input and output grounds are completely electrically independent. . However, for example, if the impedance between the input and output grounds is zero and the filter circuit F is not provided, a steep impulse-like common mode current may flow through the isolation circuit 20 due to the switching operation of the switching power supply circuit 5. flows. As a result, the amount of charge in the capacitor that forms the insulation barrier changes rapidly. Then, a steep impulse current flows through the switching elements constituting the switching power supply circuit 5, leading to destruction of the switching elements. However, this problem can be solved by providing a filter circuit FC. That is, the impulse common mode current flowing between the input and output grounds via the insulating circuit 20 is effectively suppressed by the common mode choke LC forming the filter circuit FC. Therefore, the filter circuit FC prevents the voltages of the capacitors C1 and C2 from rapidly changing due to the common mode high frequency current.

FIG. 32 shows a twenty-eighth embodiment of the present invention, in which the frequency conversion circuit 7 between the insulation circuit 20 and the load circuit 4 shown in FIG. 31 is removed, and the insulation circuit 20 is directly connected. and a load circuit 4 are connected. As a result, the alternating current that is output from the switching power supply circuit 5 and passes through the insulation circuit 20 is directly supplied to the load circuit 4 without frequency conversion. Similarly to Fig. 31, the common mode choke LC of the filter circuit FC
and the load circuit 4 in a common mode manner, and the steep impulse common mode current flowing between the input and output of the switching power supply device is more effectively blocked by the filter circuit FC.

[0053]

[Effects of the Invention] As described above, according to the present invention, by forming an insulation barrier using a capacitor, even if the current from the current source is forced to flow into the insulation circuit, an excessive surge voltage will not be generated from the insulation circuit. There isn't. therefore,
In principle, a good electromagnetic environment can be achieved without causing a large amount of interference noise on the power supply line due to leakage inductance of the insulated circuit. Furthermore, there is no risk of damage to the switching element due to excessive surge voltage caused by leakage inductance of the isolation transformer.

According to the invention shown in FIGS. 1 and 15 to 20, the current path J through which the direct current or low frequency current flows
By installing the AC current source in parallel with the AC current source, even if the AC current source contains a DC current component or a low frequency current component, the insulation barrier can be formed by the DC current component or low frequency current component of the AC current source. Very high voltages on the capacitor are avoided.

According to the inventions shown in FIGS. 5 to 7 and 21, by providing the current path J through which direct current or low frequency current flows in parallel to the switching power supply circuit,
Even if a switching power supply circuit outputs a direct current component or a low frequency current component, an extremely high voltage will be generated in the capacitor that forms the insulation barrier due to the direct current component or low frequency current component output from the switching power supply circuit. is avoided. Furthermore, the risk of destruction of the switching elements constituting the switching power supply circuit is avoided.

According to the inventions shown in FIGS. 8 to 14 and 22 to 24, by providing the current path J through which a direct current or low frequency current flows in parallel to the switching power supply circuit, the switching power supply circuit can Even when outputting low-frequency current components or low-frequency current components, it is possible to suppress or reduce the generation of high voltage in the capacitors that form the insulation barrier due to the direct current components or low-frequency current components output from the switching power supply circuit. Ru. Thereby, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit can be effectively suppressed or reduced.

According to the invention shown in FIGS. 25 to 27, by providing a current path J between the power lines between the insulation circuit and the frequency conversion circuit for discharging the charge of the capacitor constituting the insulation circuit, Even if a switching power supply circuit outputs a direct current component or a low frequency current component, a high voltage will be generated in the capacitor that forms the insulation barrier due to the direct current component or low frequency current component output from the switching power supply circuit. is suppressed or reduced. Thereby, application of unnecessary high voltage to the switching elements constituting the switching power supply circuit can be effectively suppressed or reduced.

[Brief explanation of drawings]

FIG. 1 is an electrical circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an electric circuit diagram showing an example of a conventional electric circuit.

FIG. 3 is an electrical circuit diagram showing an example of a conventional switching power supply device.

FIG. 4 is a timing chart for explaining the operation of the switching power supply shown in FIGS. 3 and 8. FIG.

FIG. 5 is an electrical circuit diagram of a second embodiment of the invention.

FIG. 6 is an electrical circuit diagram of a third embodiment of the present invention.

FIG. 7 is an electrical circuit diagram of a fourth embodiment of the present invention.

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

FIG. 9 is an electrical circuit diagram of a sixth embodiment of the present invention.

FIG. 10 is an electrical circuit diagram of a seventh embodiment of the present invention.

FIG. 11 is an electrical circuit diagram of an eighth embodiment of the present invention.

FIG. 12 is an electrical circuit diagram of a ninth embodiment of the present invention.

FIG. 13 is an electrical circuit diagram of a tenth embodiment of the present invention.

FIG. 14 is an electrical circuit diagram of an eleventh embodiment of the present invention.

FIG. 15 is an electrical circuit diagram of a twelfth embodiment of the present invention.

FIG. 16 is an electrical circuit diagram of a thirteenth embodiment of the present invention.

FIG. 17 is an electrical circuit diagram of a fourteenth embodiment of the present invention.

FIG. 18 is an electrical circuit diagram of a fifteenth embodiment of the present invention.

FIG. 19 is an electrical circuit diagram of a 16th embodiment of the present invention.

FIG. 20 is an electrical circuit diagram of a seventeenth embodiment of the present invention.

FIG. 21 is an electrical circuit diagram of an 18th embodiment of the present invention.

FIG. 22 is an electrical circuit diagram of a nineteenth embodiment of the present invention.

FIG. 23 is an electrical circuit diagram of a twentieth embodiment of the present invention.

FIG. 24 is an electrical circuit diagram of a twenty-first embodiment of the present invention.

FIG. 25 is an electrical circuit diagram of a twenty-second embodiment of the present invention.

FIG. 26 is an electrical circuit diagram of a twenty-third embodiment of the present invention.

FIG. 27 is an electrical circuit diagram of a twenty-fourth embodiment of the present invention.

28 is a timing diagram of the switching power supply device of FIG. 27. FIG.

FIG. 29 is an electrical circuit diagram of a twenty-fifth embodiment of the present invention.

FIG. 30 is an electrical circuit diagram of a twenty-sixth embodiment of the present invention.

FIG. 31 is an electrical circuit diagram of a twenty-seventh embodiment of the present invention.

FIG. 32 is an electrical circuit diagram of a twenty-eighth embodiment of the present invention.

[Explanation of symbols]

E is the DC power supply 1 is the AC current source 11 is the DC current source 3, 31, 33 is the bypass circuit J is the current path 4 is the load circuit 5, 5F, 51 is the switching power supply circuit 7 is the frequency conversion circuit 20, 20F, 22, 23, 221, 231 are insulation circuits S1 to S10, Q1 to Q4 are switching elements C1 to C
4, C1F, C2F are capacitors LDC, LAC is reactor F, FC is filter circuit

Claims (12)

[Claims] 1. An AC power supply insulation method for insulating between an AC current source and a load circuit, the method comprising: connecting a capacitor between the AC current source and the load circuit; and providing insulation by an insulation barrier of the capacitor. and a current path is provided in parallel with the alternating current source. 2. The AC power supply according to claim 1, further comprising a frequency conversion circuit connected between the capacitor and the load for converting the frequency of AC current or AC power from the AC current source. Insulation method. 3. A switching power supply device comprising: a switching power supply circuit that converts power from a power supply using magnetic energy; and an insulation barrier between an output of the switching power supply circuit and a load, wherein the insulation barrier is A switching power supply device comprising a capacitor and having a current path in parallel on the output side of the switching power supply circuit. 4. A switching power supply device comprising a cycloconverter that converts power from an AC power source through magnetic energy, and an insulation barrier on the output side of the cycloconverter, the insulation barrier comprising a capacitor, A switching power supply device comprising a current path through which a current flows in parallel to the insulating barrier. 5. A switching power supply circuit that converts power from a power supply using magnetic energy, a frequency conversion circuit that frequency converts the output of the switching power supply circuit, and between the switching power supply circuit and the frequency conversion circuit. 1. A switching power supply device comprising: an insulating barrier; and an insulating barrier, the insulating barrier comprising a capacitor, and a current path being provided in parallel with the insulating barrier. 6. Switching the power from a power source via magnetic energy to frequency convert the power to a higher frequency power than the power from the power source, bypassing the low frequency current, and passing through the insulation barrier. A method for insulating a switching power supply device, comprising the step of passing the high frequency power through an electric field as a medium. 7. A step of converting power from a power source using magnetic energy into power having a higher frequency than the power from the power source, a step of bypassing a low frequency current, and a step of converting the power of the high frequency. An insulation for a switching power supply device comprising the steps of passing the high frequency power through an insulation barrier made of a capacitor, and switching the high frequency power that has passed through the insulation barrier to convert the frequency into low frequency power. Method. 8. A step of converting power from a power source using magnetic energy into power having a higher frequency than the power from the power source, and converting the high frequency power into an insulating barrier constituted by a capacitor. an isolation step for a switching power supply device, comprising the steps of passing the electric charge through the capacitor, discharging the charge in the capacitor, and switching the high frequency power that has passed through the insulation barrier to frequency convert it into low frequency power. Method. 9. An insulation method for a switching power supply according to claim 7, further comprising the step of suppressing a common mode current passing through the insulation barrier. 10. An insulating method for a switching power supply according to claim 7, wherein the high frequency power is power at an audio frequency or higher. 11. An insulating method for a switching power supply according to claim 9, characterized in that the common mode current is suppressed using a common mode choke. 12. An insulating method for a switching power supply according to claim 9, characterized in that the common mode current is suppressed using a reactor.