JP2020137298A - Capacitor and insulation circuit - Google Patents

Abstract

To realize an insulation circuit which electrically insulates a primary side and a secondary side, and can transfer a DC power to both directions between the primary side and the secondary side.SOLUTION: An insulation circuit 10 comprises: a capacitor 20; and first to fourth bidirectional semiconductor switching circuits 30-1 to 30-4. In the capacitor 20, a first electrode pair 25 which functions as a first capacitor connected to a first terminal pair 21 on a primary side and a second electrode pair 27 that functions as a second capacitor connected to a second terminal pair 23 of a secondary side are arranged to partially face each other so as to be bound to a magnetic field. An ON control of the bidirectional semiconductor switching circuits 30-1 and 30-2 and an ON control of the bidirectional semiconductor switching circuits 30-3 and 30-4 are alternately performed, thereby supplying a DC power to the secondary side from the primary side or to the primary side from the secondary side.SELECTED DRAWING: Figure 1

Description

The present invention relates to an insulating circuit or the like that electrically insulates the primary side and the secondary side to accommodate DC power.

The main circuit of a conventional AC electric vehicle is configured to include a main transformer, a converter, and an inverter (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-308205

When trying to miniaturize the main circuit of an AC electric vehicle (reduce volume and weight), it is conceivable to reduce the size of each component, but a new main circuit that changes the device configuration of the main circuit itself. Should also be considered. For example, a new main circuit configuration that does not require a main transformer can be considered. However, in addition to the function of stepping down the AC overhead line voltage, the main transformer has an important function of electrically insulating the overhead line side and the drive circuit side of an electric motor or the like. Further, in an electric vehicle, since the electric motor is used for regenerative braking, even in a new main circuit, the forward direction of supplying electric power from the overhead wire side to the electric motor side and the reverse direction of regenerating electric power from the electric motor side to the overhead wire side. It is necessary to operate in both directions.

In addition, although the example of an electric vehicle is given, for technical applications where it is desired to electrically insulate the primary side and the secondary side and to accommodate DC power in both directions between the primary side and the secondary side. Therefore, similar requirements can be considered.

The problem to be solved by the present invention is to realize an insulating circuit that electrically insulates the primary side and the secondary side and can exchange DC power in both directions between the primary side and the secondary side, particularly. In order to realize the insulation circuit, it is necessary to realize an elemental circuit that plays a key role in accommodating DC power.

The first invention for solving the above problems is
1st terminal pair and 2nd terminal pair,
A first electrode pair that functions as a first capacitor connected to the first terminal pair,
A second electrode pair that functions as a second capacitor connected to the second terminal pair,
With
The first electrode pair and the second electrode pair are partially opposed to each other so as to be electrically coupled.
A capacitor that outputs DC power intermittently applied to one of the first terminal pair and the second terminal pair from the other.

According to the first invention, the first terminal pair and the second terminal pair are not in a physically connected conductive state, but the first electrode pair and the second electrode pair are arranged so as to be electrically coupled to each other. Therefore, it is possible to realize a capacitor that outputs the DC power applied to one terminal pair of the first terminal pair and the second terminal pair from the other terminal pair. That is, when DC power is applied to one terminal pair, one electrode pair connected to the one terminal pair is stored, and the other electrode pair is also stored by electric field coupling. When DC power is no longer applied to one terminal pair, the stored power of the other electrode pair is discharged and DC power is output from the other terminal pair. Therefore, by using this capacitor, it is possible to realize an insulating circuit that electrically insulates the primary side and the secondary side and can exchange DC power in both directions between the primary side and the secondary side. This capacitor is an element circuit that plays a key role in accommodating DC power in realizing the insulation circuit.

As the configuration in which the first electrode pair and the second electrode pair are partially opposed to each other so as to be electrically coupled, various configurations can be specifically considered.
For example, as a second invention, in the first invention,
The facing arrangement was made by arranging the electrode elements of the other electrode pair so as to be partially sandwiched between the two electrode elements constituting the first electrode pair and one electrode pair of the second electrode pair. ,
A capacitor may be realized.

Further, as a third invention, in the first or second invention,
The two electrode elements constituting the first electrode pair and the two electrode elements constituting the second electrode pair were arranged so as to partially overlap each other to form the facing arrangement.
A capacitor may be realized.

Further, as a fourth invention, in the first invention,
Each electrode element constituting the first electrode pair has a basic facing portion that functions as the first capacitor and a bent portion that faces the second electrode pair.
Each electrode element constituting the second electrode pair has a basic facing portion that functions as the second capacitor and a bent portion that faces the first electrode pair.
A capacitor may be realized.

The fifth invention is the fifth invention in any one of the first to fourth inventions.
The first terminal pair has a first positive electrode terminal and a first negative electrode terminal.
The second terminal pair has a second positive electrode terminal and a second negative electrode terminal.
The first electrode pair has a first positive electrode element connected to the first positive electrode terminal and a first negative electrode element connected to the first negative electrode terminal.
The second electrode pair has a second positive electrode element connected to the second positive electrode terminal and a second negative electrode element connected to the second negative electrode terminal.
The first positive electrode element and the second positive electrode element are partially arranged to face each other.
The first negative electrode element and the second negative electrode element are partially opposed to each other.
It is a capacitor.

According to the fifth invention, the positive electrode elements of the first electrode pair and the second electrode pair are partially opposed to each other, and the negative electrode elements are partially opposed to each other, whereby the first electrode pair and the second electrode pair are arranged. It is possible to form a capacitor in which two electrode pairs are partially opposed to each other so as to be electrically coupled.

The sixth invention is
It is an insulation circuit that electrically insulates between the primary side and the secondary side to accommodate DC power.
With the capacitor of any of the first to fifth inventions,
A first bidirectional semiconductor switch circuit provided between the primary side of the high-voltage side line and the first positive electrode terminal of the first terminal pair,
A second bidirectional semiconductor switch circuit provided between the primary side of the low voltage side line and the first negative electrode terminal of the first terminal pair,
A third bidirectional semiconductor switch circuit provided between the secondary side of the high-voltage side line and the second positive electrode terminal of the second terminal pair,
A fourth bidirectional semiconductor switch circuit provided between the secondary side of the low voltage side line and the second negative electrode terminal of the second terminal pair,
With
By alternately performing the ON control of the first bidirectional semiconductor switch circuit and the second bidirectional semiconductor switch circuit and the ON control of the third bidirectional semiconductor switch circuit and the fourth bidirectional semiconductor switch circuit. An insulating circuit that supplies DC power from the primary side to the secondary side, or from the secondary side to the primary side.

According to the sixth invention, it is possible to realize an insulating circuit that electrically insulates the primary side and the secondary side and can exchange DC power in both directions between the primary side and the secondary side. That is, the first and second bidirectional semiconductor switch circuits connected to the first terminal pair of the capacitor and the third and fourth bidirectional semiconductor switch circuits connected to the second terminal pair are alternately turned on and controlled. Then, the capacitor (electrode pair) is stored and the stored power is discharged alternately, and the DC power applied to one terminal pair of the first terminal pair on the primary side and the second terminal pair on the secondary side is applied. , Can be output to the other terminal pair. As a result, it is possible to realize an insulating circuit capable of accommodating DC power in both directions while electrically insulating the primary side and the secondary side.

The seventh invention is the sixth invention.
The first to fourth bidirectional semiconductor switch circuits are configured by connecting a basic circuit in which diode elements are connected in antiparallel to a switching element in series so that the forward directions of the diode elements face each other.
It is an insulated circuit.

According to the seventh invention, a bidirectional semiconductor switch circuit is configured by connecting a basic circuit in which a diode element is connected in antiparallel to a switching element in series so that the forward directions of the diode elements face each other. The flow direction can be limited to one direction depending on which of the two switching elements is on-controlled as the on-control of the switch circuit.

Configuration example of an insulated circuit. Principle structural example of a capacitor. An example of an equivalent circuit by electric field coupling. Other configuration examples of insulation circuit controls. The operation explanatory drawing of the insulation circuit at the time of power running operation. An operation explanatory diagram of an insulation circuit during regenerative operation. Configuration example of an inverter incorporating an insulation circuit. Configuration diagram of the simulation circuit. Graph of simulation results. The main circuit block diagram for an AC electric vehicle in 1st Example. The main circuit block diagram for the AC electric vehicle in the 2nd Example. Other structural examples of capacitors. Other structural examples of capacitors.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below do not limit the present invention, and the embodiments to which the present invention can be applied are not limited to the following embodiments. Further, in the description of the drawings, the same elements are designated by the same reference numerals.

[Circuit configuration]
FIG. 1 is a diagram showing a circuit configuration of the insulation circuit 10 of the present embodiment. According to FIG. 1, in the insulation circuit 10, the primary side is connected to the DC power supply side, the secondary side is connected to the inverter 50 that drives the electric motor 60, and the primary side and the secondary side are electrically insulated to form a DC. It is a circuit that accommodates electric power and is installed in the middle of the power supply line. The inverter 50 may drive and control one electric motor as a so-called 1C1M, or may drive and control a plurality of electric motors as 1C2M or 1C4M.

As the inverter 50 connected to the secondary side of the insulation circuit 10, a conventional inverter can be used. A capacitor (filter capacitor) is generally provided in the input stage of the conventional inverter (broken line in FIG. 1). When using an inverter without a capacitor, a capacitor is provided in the output stage of the insulation circuit 10 (between the high voltage side line HL on the secondary side and the low voltage side line LL) to smooth the output voltage and output. You may.

Further, the primary side of the insulation circuit 10 is connected to a power supply line, a power supply circuit, a DC stabilization circuit, a converter, and the like. A capacitor (filter capacitor) is usually provided in the output stage on the power supply side for voltage stabilization and the like (broken line in FIG. 1). When a capacitor is not provided, a capacitor may be provided in the input stage of the insulation circuit 10 (between the high voltage side line HL on the primary side and the low voltage side line LL).

The insulation circuit 10 includes a capacitor 20 and four bidirectional semiconductor switch circuits 30 (30-1 to 30-4).

The capacitor 20 has a first terminal pair 21 having a first positive electrode terminal 22a and a first negative electrode terminal 22b and being connected to the primary side of the insulation circuit 10, and a second positive electrode terminal 24a and a second negative electrode terminal 24b. It has a second terminal pair 23 connected to the secondary side of the insulation circuit 10.

The bidirectional semiconductor switch circuit 30 is configured by connecting two basic circuits in which a switching element and a diode element are connected in antiparallel to each other in series so that the forward directions of the diode elements face each other. The bidirectional semiconductor switch circuit 30 can control the flow direction depending on which switching element is on-controlled. Assuming that the high voltage side (for example, the positive side or the non-grounded side) of the power supply line is the high voltage side line HL and the low voltage side (for example, the negative side or the grounded side) is the low voltage side line LL, the bidirectional semiconductor switch circuit 30-1 The bidirectional semiconductor switch circuit 30-2 is provided between the high voltage side line HL on the primary side and the first positive electrode terminal 22a of the capacitor 20, and the bidirectional semiconductor switch circuit 30-2 is provided between the low voltage side line LL on the primary side and the first negative electrode terminal of the capacitor 20. It is provided between 22b. The bidirectional semiconductor switch circuit 30-3 is provided between the high voltage side line HL on the secondary side and the second positive electrode terminal 24a of the capacitor 20, and the bidirectional semiconductor switch circuit 30-4 is a low voltage side on the secondary side. It is provided between the side line LL and the second negative electrode terminal 24b of the capacitor 20.

A so-called power device can be used as the switching element and the diode element constituting the bidirectional semiconductor switch circuit 30. For example, in addition to GTO (Gate Turn-Off thyristor) and IGBT (Insulated Gate Bipolar Transistor), Si-IGBT (Silicon-Insulated Gate Bipolar Transistor), SiC-SBD (Silicon Carbide-Schottky Barrier Diode), SiC-MOSFET, SiC -It can be appropriately selected depending on the working voltage of the insulating circuit 10, such as IGBT.

FIG. 2 is a diagram showing a principle structure of the capacitor 20. According to FIG. 2, the capacitor 20 includes a first electrode pair 25 that functions as a first capacitor and a second electrode pair 27 that functions as a second capacitor. The first electrode pair 25 is configured such that the first positive electrode element 26a connected to the first positive electrode terminal 22a and the first negative electrode element 26b connected to the first negative electrode terminal 22b are arranged to face each other. The second electrode pair 27 is configured such that the second positive electrode element 28a connected to the second positive electrode terminal 24a and the second negative electrode element 28b connected to the second negative electrode terminal 24b are arranged to face each other. That is, the first terminal pair 21 and the second terminal pair 23 are not in a physically connected conductive state.

Further, the first electrode pair 25 and the second electrode pair 27 are partially opposed to each other so as to be electrically coupled. Specifically, it is arranged so as to partially sandwich one electrode element of the other electrode pair between the two electrode elements constituting one electrode pair of the first electrode pair 25 and the second electrode pair 27. Are facing each other. More specifically, the first positive electrode element 26a and the first negative electrode element 26b, which are the two electrode elements constituting the first electrode pair 25, and the second electrode element, which is the two electrode elements constituting the second electrode pair 27. The positive electrode element 28a and the second negative electrode element 28b are arranged so as to partially overlap each other.

The area of the electrode element of the first electrode pair 25 is S ₁ , the distance between the electrode elements is d ₁ , the area of the electrode element of the second electrode pair 27 is S ₂ , and the distance between the electrode elements is d ₂ . The first positive electrode element 26a, the second positive electrode element 28a, the second negative electrode element 28b, the area of the opposed portion where the second negative electrode element 28b mutually overlap _{S m,} the distance between opposing portions and _{d m} .. When the DC voltages V ₁ is applied between the first positive terminal 22a and the first negative terminal 22b, and the DC voltage V2 between the second positive terminal 24a and the second negative terminal 24b is applied, the The electric charge Q ₁ stored in the 1-electrode pair 25 and the electric charge Q ₂ stored in the 2nd electrode pair 27 are given by the following equations (1) and (2), respectively, using the electric flux density D.

In the formula (1), D ₁ is the electric flux density between the electrode elements of the portion of the first electrode pair 25 that does not overlap with the second electrode pair 27, and the dielectric constant between the electrode elements is ε ₁ , and the formula ( ₁ ) Given in 3). In the formula (2), D ₂ is the electric flux density between the electrode elements in the portion of the second electrode pair 27 that does not overlap with the first electrode pair 25, and the dielectric constant between the electrode elements is ε ₂ , and the formula ( ₂ ) It is given in 4). In the formulas (1) and (2), D _m is the electric flux density between the facing portions where the first electrode pair 25 and the second electrode pair 27 overlap, and the dielectric constant between the facing portions is ε _m . It is given by the following equation (5).

なお、式（６），（７）における誘電率ε_１，ε_２，ε_ｍは、電極素子間で全て等しく、ε_１＝ε_２＝ε_ｍ＝ε、としても良い。 Using equations (3) to (5), equations (1) and (2) are transformed into the following equations (6) and (7).

The dielectric constants ε ₁ , ε ₂ , and ε _m in the equations (6) and (7) are all equal between the electrode elements, and ε ₁ = ε ₂ = ε _m = ε may be set.

Further, as shown in FIG. 3, when two capacitors are electrically coupled, the coupling portion can be indicated by an equivalent circuit of a π-type circuit. Since the capacitor 20 of the present embodiment is configured by arranging the first electrode pair 25 and the second electrode pair 27 that function as capacitors so as to be electrically coupled, if it is represented by the equivalent circuit of FIG. 3, the capacitor 20 formula for (6), (7), the capacitance _C 1, C2, _{C m,} respectively, in the equivalent circuit, the following equation holds (8) to (10).

[Circuit operation]
Next, the operation of the insulation circuit 10 will be described. The insulation circuit 10 basically operates in accordance with the operation of the inverter 50. Therefore, in the present embodiment, the control device 40 of the inverter 50 has a function of controlling the operation of the insulation circuit 10. Specifically, the control device 40 has an insulation circuit control device 41, and the insulation circuit control device 41 is controlling a regenerative operation in which the inverter 50 supplies electric power to the electric motor 60 to generate a tensile force. An operation instruction signal for instructing on / off is output to each bidirectional semiconductor switch circuit 30 (30-1 to 30-4) depending on whether the regenerative operation using the electric motor 60 as a regenerative brake is being controlled. As a result, the operation of the insulation circuit 10 is switched. Since the bidirectional semiconductor switch circuit 30 has two switching elements connected in series, which switching element is used so that the operation instruction signal for the bidirectional semiconductor switch circuit 30 is in the flow direction according to the operation of the inverter 50. It becomes a signal instructing whether to turn on.

As shown in FIG. 4, the insulation circuit control device 41 is configured as a device separate from the control device 40 of the inverter 50, and is the insulation circuit control device 41 being controlled by the control device 40 for power running operation? The operation of the insulation circuit 10 may be controlled by inputting a signal indicating whether the regenerative operation is being controlled.

The operation of the insulation circuit 10 will be specifically described with reference to FIGS. 5 and 6. FIG. 5 is a diagram for explaining the operation of the insulation circuit 10 during power running operation. During the power running operation, the insulation circuit 10 is bidirectional with the state of FIG. 5 (1) in which the bidirectional semiconductor switch circuits 30-1 and 30-2 are on-controlled according to the operation instruction signal from the insulation circuit control device 41. The state shown in FIG. 5 (2), in which the semiconductor switch circuits 30-3 and 30-4 are turned on and controlled, is alternately switched.

Specifically, in the state of FIG. 5 (1), for the bidirectional semiconductor switch circuit 30-1, the switching element closer to the first positive electrode terminal 22a of the capacitor 20 is turned on and controlled, and the bidirectional semiconductor switch circuit For 30-2, by controlling on the switching element farther from the first negative electrode terminal 22b of the capacitor 20, the high-voltage side line HL on the primary side passes through the capacitor 20 and the low-voltage side line LL on the primary side. The direction toward is the flow direction.

Further, in the state of FIG. 5 (2), with respect to the bidirectional semiconductor switch circuit 30-3, the switching element farther from the second positive electrode terminal 24a of the capacitor 20 is turned on and controlled, and the bidirectional semiconductor switch circuit 30-4 is controlled. By turning on the switching element closer to the second negative electrode terminal 24b of the capacitor 20, the low-voltage side line LL on the secondary side is changed to the high-voltage side line HL on the secondary side via the capacitor 20. The direction of travel is the flow direction.

Therefore, the electric power supplied from the power supply side in the state of FIG. 5 (1) is stored in the capacitor 20, and the stored electric power of the capacitor 20 is discharged and supplied to the inverter 50 in the state of FIG. 5 (2). Therefore, the primary side and the secondary side of the insulation circuit 10 are electrically insulated, and DC power is supplied from the primary side to the secondary side. The frequency for switching between the state of FIG. 5 (1) and the state of FIG. 5 (2) can be appropriately set according to the specifications of the inverter 50.

FIG. 6 is a diagram for explaining the operation of the insulation circuit during the regenerative operation. During the regenerative operation, the insulation circuit 10 is bidirectional with the state of FIG. 6 (1) in which the bidirectional semiconductor switch circuits 30-3 and 30-4 are on-controlled according to the operation instruction signal from the insulation circuit control device 41. The state shown in FIG. 6 (2), in which the semiconductor switch circuits 30-1 and 30-2 are turned on and controlled, is alternately switched.

Specifically, in the state of FIG. 6 (1), for the bidirectional semiconductor switch circuit 30-3, the switching element closer to the second positive electrode terminal 24a of the capacitor 20 is turned on and controlled, and the bidirectional semiconductor switch circuit For 30-4, by controlling the switching element farther from the second negative electrode terminal 24b of the capacitor 20 on, the high voltage side line HL on the secondary side passes through the capacitor 20 and the low voltage side on the secondary side. The direction toward the line LL is the flow direction.

Further, in the state of FIG. 6 (2), for the bidirectional semiconductor switch circuit 30-1, the switching element farther from the first positive electrode terminal 22a of the capacitor 20 is turned on and controlled, and the bidirectional semiconductor switch circuit 30-2 is controlled. By controlling the switching element closer to the first negative electrode terminal 22b of the capacitor 20 on, the direction from the low voltage side line LL on the primary side to the high voltage side line HL on the primary side via the capacitor 20. Is the flow direction.

The regenerative power supplied from the inverter 50 in the state of FIG. 6 (1) is stored in the capacitor 20, and the stored power of the capacitor 20 is discharged in the state of FIG. 6 (2) and supplied to the power supply side. Therefore, the primary side and the secondary side of the insulation circuit 10 are electrically insulated, and DC power is supplied from the secondary side to the primary side. The frequency for switching between the state of FIG. 6 (1) and the state of FIG. 6 (2) can be appropriately set according to the specifications of the inverter 50.

Although the insulation circuit 10 has been described above, since the insulation circuit 10 operates in accordance with the operation of the inverter 50, the insulation circuit 10 may be incorporated into the inverter 50. Specifically, as shown in FIG. 7, an inverter 51 having an insulation circuit 10 in front of a power conversion circuit 53 that supplies drive power obtained by converting DC power to AC power to an electric motor 60 may be configured. .. Further, although FIG. 7 illustrates a configuration in which the control device 40 is also integrated, the control device 40 may be a device separate from the inverter 51.

[Test results]
Subsequently, the test results for the insulating circuit 10 will be described. The test was performed as a simulation for the equivalent circuit of the insulation circuit 10. FIG. 8 shows the configuration of the simulation circuit. As shown in FIG. 8, in the simulation circuit, the insulating circuit 10 is configured by using the capacitor 20 as the equivalent circuit shown in FIG. The primary side of the isolation circuit 10 (power supply side) connecting the DC power supply V _i of the DC 3000 V, a load resistance R of the smoothing capacitor and 30Ω connected in parallel to the secondary side, the secondary from the primary side of the isolation circuit 10 The case of supplying DC power to the side was simulated. Then, the primary side current i ₁ flowing from the high voltage side line HL on the primary side of the insulation circuit 10 toward the capacitor 20, and the secondary side current i ₁ flowing from the capacitor 20 toward the high voltage side line HL on the secondary side of the insulation circuit 10. _{2. The} voltage across the smoothing capacitor V _B , which is the output voltage on the secondary side, and the load current i _out flowing through the load R were measured.

FIG. 9 is a simulation result for the simulation circuit of FIG. In FIG. 9, the horizontal axis is time, the vertical axis on the right side is voltage, and the vertical axis on the left side is current, and the power supply voltage V _i , output voltage V _B , primary side current i ₁ , secondary side current i ₂ , and load current i Each of _out is shown. The switching cycle between the on-control of the bidirectional semiconductor switch circuits 30-1 and 30-2 on the primary side and the on-control of the bidirectional semiconductor switch circuits 30-3 and 30-4 on the secondary side is 0.025 ms. (= 40 kHz).

According to FIG. 9, the power supply voltage _{V i} of the DC 3000 V, it was obtained output voltage _{V B} of about approximately equal DC 2850V. Further, the load current _{i out} of DC 100A was obtained. That is, it can be seen that the DC power is supplied from the primary side (power supply side) to the secondary side (load side) of the insulation circuit 10. Further, the primary side current i ₁ and the secondary side current i ₂ do not flow at the same time. In particular, the simultaneous communication flow of the current i _1, i _2, since not occur at the time of switching between the charging operation and the discharging operation of the capacitor 20, the primary side of the isolation circuit (power supply side) and the secondary side (load side ) And are electrically insulated.

[Example]
Next, two examples in which the insulation circuit 10 is applied to the main circuit of the AC electric vehicle will be described.
<First Example>
FIG. 10 is a diagram showing a main circuit of an AC electric vehicle according to the first embodiment. As shown in FIG. 10, the main circuit of the AC electric train is electrically connected to the overhead wire 2 via a switch 5 such as a pantograph 3 and a vacuum breaker, and is electrically connected to a rail 8 via a wheel shaft 7. By being connected, the overhead wire voltage is applied. The overhead wire voltage is input to the converter 70. In the main circuit of a conventional AC electric vehicle, a main transformer for stepping down and insulating the overhead wire voltage is provided, but in this embodiment, the main transformer is not used.

N (N ≧ 2) insulation circuits 10 (10-1 to 10-N) are connected in parallel to the output side of the converter 70. Then, an inverter 50 (50-1 to 50-N) is connected to the secondary side of each insulation circuit 10. All of the N inverters 50 may control the drive of the electric motor 60, but in FIG. 10, M (N> M) of the N inverters 50 control the electric motor 60, and the remainder. Inverter 50 functions as a so-called SIV (static inverter).

The converter 70 converts the AC overhead wire voltage into a DC voltage higher than the AC overhead wire voltage. For example, when the overhead line voltage is AC 25,000 V, it is converted to DC 30000 V. The output voltage from the converter 70 is divided into each insulation circuit 10. Further, the switching operation of each insulation circuit 10 is performed synchronously. Therefore, although not shown in FIG. 10, the control device 40 (or the insulation circuit control device 41) corresponding to each insulation circuit 10 outputs an operation instruction signal in synchronization with the corresponding insulation circuit 10. ..

<Second Example>
FIG. 11 is a diagram showing a main circuit of the AC electric vehicle in the second embodiment. In the second embodiment, as in the first embodiment, a configuration in which the overhead wire voltage is input to the converter 70 without using the main transformer is adopted, but the circuit configuration after the converter 70 is the same as that of the first embodiment. different. In the second embodiment, N step-down circuits 80 (80-1 to 80-N) connected in parallel are connected to the output side of the converter 70. The step-down circuit 80 can be configured by, for example, a chopper circuit. The primary side of the insulation circuit 10 (10-1 to 10-N) is connected to the output side of each step-down circuit 80, and the inverter 50 (50-1 to 50) is connected to the secondary side of the insulation circuit 10. −N) is connected. It is the same as the first embodiment that the switching operation of each insulation circuit 10 is performed in synchronization. Therefore, although not shown in FIG. 11, the control device 40 (or the insulation circuit control device 41) corresponding to each insulation circuit 10 outputs an operation instruction signal in synchronization with the corresponding insulation circuit 10. ..

[Action effect]
As described above, according to the present embodiment, it is possible to realize an insulating circuit 10 that electrically insulates the primary side and the secondary side and can exchange DC power in both directions between the primary side and the secondary side. Can be done. In the capacitor 20 of the insulation circuit 10, the first electrode pair 25 connected to the first terminal pair 21 on the primary side and the second electrode pair 27 connected to the second terminal pair 23 on the secondary side have an electric field. It is configured to be partially opposed so that it can be combined. That is, the first terminal pair 21 and the second terminal pair 23 of the capacitor 20 are not in a physically connected conductive state, but when DC power is applied to one terminal pair, the other terminal pair is connected. One of the connected electrode pairs is stored, and the other electrode pair is also stored by electric field coupling. When DC power is no longer applied to one terminal pair, the stored power of the other electrode pair is discharged and DC power is output from the other terminal pair. Therefore, it can be said that the capacitor 20 is an element circuit that plays a key role in accommodating DC power in realizing the insulation circuit 10.

[Modification example]
It should be noted that the applicable embodiment of the present invention is not limited to the above-described embodiment, and of course, it can be appropriately changed without departing from the spirit of the present invention.

(A) Structure of Capacitor 20 In the capacitor 20, two electrode pairs (first electrode pair 25 and second electrode pair 27) that function as capacitors may be partially arranged so as to be electrically coupled to each other, for example. , The structure as shown in FIGS. 12 and 13 may be used.

The capacitor 20A shown in FIG. 12 includes a basic facing portion 29a in which the first positive electrode element 26a and the first negative electrode element 26b constituting the first electrode pair 25 each face each other and function as a first capacitor, and the basic It has a bent portion 29b that is bent from the end of the facing portion 29a and faces the bent portion 29d of each of the second positive electrode element 28a and the second negative electrode element 28b of the second electrode pair 27. Similarly, for the second electrode pair 27, the second positive electrode element 28a and the second negative electrode element 28b constituting the second electrode pair 27 each face each other and function as a second capacitor, and a basic opposed portion 29c. It has a bent portion 29d facing the bent portion 29b of each of the first positive electrode element 26a and the first negative electrode element 26b of the first electrode pair 25, which is bent from the end portion of the basic facing portion 29c.

Similar to the embodiment described above, the bent portion 29b to be disposed opposite the portion of the first electrode pair 25 and the second electrode pair 27, the area of the 29d _{S m,} facing bent portion 29b, the distance between 29d d When _m, the charge _Q 1, Q2 to be accumulated in each of the first electrode pair 25 and the second electrode pair 27, respectively, the following equation (11) given by (12).

The capacitor 20A can also be represented by the equivalent circuit shown in FIG. 3, and the following equations (16) to (18) hold for each of the capacitances C ₁ , C ₂ , and C _m in the equivalent circuit.

Further, in the capacitor 20B shown in FIG. 13, the two electrode elements of the second electrode pair 27 (the first electrode element 26a and the first negative electrode element 26b) are sandwiched between the two electrode elements of the first electrode pair 25. The second positive electrode element 28a and the second negative electrode element 28b) are configured to partially sandwich the first electrode pair 25 and the second electrode pair 27 so as to be partially opposed to each other so as to be electrically coupled to each other. ing. Even with this configuration, the capacitor 20 can function as long as various conditions such as the facing area and the facing spacing are met.

Further, in the above embodiment, an example of an electric train has been given, but for technical applications in which DC power is exchanged in both directions between the primary side and the secondary side, the above-mentioned insulation circuit 10 and capacitor 20 (20A) are used. , 20B included) can be applied in the same manner.

10 ... Insulation circuit 20 ... Condenser 21 ... 1st terminal vs. 22a ... 1st positive electrode terminal, 22b ... 1st negative electrode terminal 23 ... 2nd terminal vs. 24a ... 2nd positive electrode terminal, 24b ... 2nd negative electrode terminal 25 ... 1st electrode 26a ... 1st positive electrode element, 26b ... 1st negative electrode element 27 ... 2nd electrode pair 28a ... 2nd positive electrode element, 28b ... 2nd negative electrode element 30 (30-1 to 30-4) ... Bidirectional Semiconductor switch circuit 40 ... Control device, 41 ... Insulation circuit control device 50 ... Inverter, 60 ... Electric motor HL ... High-voltage side line, LL ... Low-voltage side line

Claims (7)

1st terminal pair and 2nd terminal pair,
A first electrode pair that functions as a first capacitor connected to the first terminal pair,
A second electrode pair that functions as a second capacitor connected to the second terminal pair,
With
The first electrode pair and the second electrode pair are partially opposed to each other so as to be electrically coupled.
A capacitor that outputs DC power intermittently applied to one of the first terminal pair and the second terminal pair from the other. The facing arrangement was made by arranging the electrode elements of the other electrode pair so as to be partially sandwiched between the two electrode elements constituting the first electrode pair and one electrode pair of the second electrode pair. ,
The capacitor according to claim 1. The two electrode elements constituting the first electrode pair and the two electrode elements constituting the second electrode pair were arranged so as to partially overlap each other to form the facing arrangement.
The capacitor according to claim 1 or 2. Each electrode element constituting the first electrode pair has a basic facing portion that functions as the first capacitor and a bent portion that faces the second electrode pair.
Each electrode element constituting the second electrode pair has a basic facing portion that functions as the second capacitor and a bent portion that faces the first electrode pair.
The capacitor according to claim 1. The first terminal pair has a first positive electrode terminal and a first negative electrode terminal.
The second terminal pair has a second positive electrode terminal and a second negative electrode terminal.
The first electrode pair has a first positive electrode element connected to the first positive electrode terminal and a first negative electrode element connected to the first negative electrode terminal.
The second electrode pair has a second positive electrode element connected to the second positive electrode terminal and a second negative electrode element connected to the second negative electrode terminal.
The first positive electrode element and the second positive electrode element are partially arranged to face each other.
The first negative electrode element and the second negative electrode element are partially opposed to each other.
The capacitor according to any one of claims 1 to 4. It is an insulation circuit that electrically insulates between the primary side and the secondary side to accommodate DC power.
The capacitor according to any one of claims 1 to 5,
A first bidirectional semiconductor switch circuit provided between the primary side of the high-voltage side line and the first positive electrode terminal of the first terminal pair,
A second bidirectional semiconductor switch circuit provided between the primary side of the low voltage side line and the first negative electrode terminal of the first terminal pair,
A third bidirectional semiconductor switch circuit provided between the secondary side of the high-voltage side line and the second positive electrode terminal of the second terminal pair,
A fourth bidirectional semiconductor switch circuit provided between the secondary side of the low voltage side line and the second negative electrode terminal of the second terminal pair,
With
By alternately performing on-control of the first bidirectional semiconductor switch circuit and the second bidirectional semiconductor switch circuit and on-control of the third bidirectional semiconductor switch circuit and the fourth bidirectional semiconductor switch circuit. An insulating circuit that supplies DC power from the primary side to the secondary side, or from the secondary side to the primary side. The first to fourth bidirectional semiconductor switch circuits are configured by connecting a basic circuit in which diode elements are connected in antiparallel to a switching element in series so that the forward directions of the diode elements face each other.
The insulating circuit according to claim 6.

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