JP2001025257A - Rectifying circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power conversion efficiency and to simplify check and maintenance works by setting currents from a three-phase AC power source into substantially sinusoidal shapes in a rectifying circuit, for converting the voltages of the power source to arbitrary DC voltages to supply voltages to a load. SOLUTION: This rectifying circuit comprises first main circuits 11 to 13, in which back-to-back circuits of IGBTs and diodes are sired in full bridge circuits, AC reactors L1 to L3, and a DC reactor L0. In this case, the IGBTs are combined arbitrarily, turned on and off to convert an AC power into a desired DC voltage. With this circuit configuration, smoothing electrolytic capacitors which have been used as periodically replacing components in conventional rectifying circuits are dispensed with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifier circuit that converts a three-phase AC voltage into an arbitrary DC voltage and supplies the DC voltage to a load.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram showing a first conventional example of this type of rectifier circuit, wherein 1 is a three-phase AC power supply, 2 is a diode rectifier connected in a three-phase bridge configuration, and 3 is Electrolytic capacitor 4 for smoothing, DC chopper circuit 4 and load 5.

In the rectifier circuit shown in FIG. 5, the voltage of a three-phase AC power supply 1 is full-wave rectified by a diode rectifier 2, the full-wave rectified voltage is converted to a DC voltage smoothed by an electrolytic capacitor 3, and this DC voltage is converted to a DC voltage. The DC voltage is converted into an arbitrary DC voltage by the DC chopper circuit 4 and supplied to the load 5.

FIG. 6 is a circuit diagram showing a second conventional example of this type of rectifier circuit, in which components having the same functions as those of the circuit configuration shown in FIG. That is, in the rectifier circuit shown in FIG. 6, instead of the diode rectifier 2 shown in FIG.
A self-excited rectifier 6 is provided in which a switch circuit formed by connecting a GBT and a diode in anti-parallel is connected in a three-phase bridge configuration.

[0005] In the rectifier circuit shown in FIG.
Thus, the voltage can be increased to a value equal to or higher than the full-wave rectified voltage value of the three-phase AC power supply 1. This voltage is converted to a DC voltage smoothed by the electrolytic capacitor 3, and this DC voltage is converted by the DC chopper circuit 4. The voltage is converted to an arbitrary DC voltage and supplied to the load 5.

[0006]

In the conventional rectifier circuit shown in FIG. The current from the three-phase AC power supply 1 contains many harmonics,. The number of power conversion stages becomes two, and the conversion efficiency of this rectifier circuit is reduced. There is a problem that an electrolytic capacitor for smoothing is required, and since this electrolytic capacitor is a wear-life component, it requires periodic replacement.

In the conventional rectifier circuit shown in FIG.
By controlling the IGBT constituting the self-excited rectifier 6 by PWM control, the current from the three-phase AC power supply 1 can be made substantially sinusoidal. The number of power conversion stages becomes two, and the conversion efficiency of this rectifier circuit is reduced. There is a problem that an electrolytic capacitor for smoothing is required, and since this electrolytic capacitor is a wear-life component, it requires periodic replacement. An object of the present invention is to provide a rectifier circuit that solves the above problems.

[0008]

A rectifier circuit according to a first aspect of the present invention includes a first switch circuit to a twelfth switch circuit formed by connecting a self-extinguishing element and a diode in antiparallel. The first to fourth switch circuits are connected in a full bridge configuration to form a first main circuit; the fifth to eighth switch circuits are connected in a full bridge configuration to form a second main circuit; A circuit from the circuit to the twelfth switch circuit is connected in a full bridge configuration to form a third main circuit, and an intermediate connection point between one of the upper and lower arms of the first main circuit is directly or via a first AC reactor. And a middle connection point between one of the upper and lower arms of the second main circuit is connected to the second phase of the three-phase AC power supply directly or via a second AC reactor. Upper and lower ar Is connected to the third phase of the three-phase AC power supply directly or via a third AC reactor, and the intermediate connection point of the other upper and lower arms of the first main circuit, and the second main circuit And an intermediate connection point between the other upper and lower arms of the third main circuit and an intermediate connection point between the other upper and lower arms of the third main circuit. The connection point between the upper arm and the lower arm from the circuit to the third main circuit is connected to each other, and the connection point is connected to the other end of the load.

A rectifier circuit according to a second aspect of the present invention includes a first switch circuit to a ninth switch circuit formed by connecting a self-extinguishing element and a diode in anti-parallel, a first diode, and a second diode. And a third diode, wherein the first to third switch circuits and the first diode are connected in a full bridge configuration to form a first main circuit, and the fourth to sixth switch circuits. , The second diode is connected in a full bridge configuration to form a second main circuit, and the seventh to ninth switch circuits and the third diode are connected in a full bridge configuration to form a third main circuit. An intermediate connection point between the upper and lower arms of only the switch circuit of one main circuit is connected directly or via a first AC reactor to the first phase of a three-phase AC power supply, and the switch circuit of the second main circuit is connected to the first phase. The intermediate connection point between the upper and lower arms is connected to the second phase of the three-phase AC power supply directly or via a second AC reactor, and the intermediate connection point between the upper and lower arms of only the switch circuit of the third main circuit. Directly or via a third AC reactor to the third phase of the three-phase AC power supply, and connect the intermediate connection point between the upper and lower arms of the first main circuit and the other of the second main circuit. , The middle connection point of the lower arm and the middle connection point of the upper and lower arms of the other of the third main circuit are connected to each other, and this connection point is connected to one end of the load. The upper-arm connection point or the lower-arm connection point up to the main circuit is connected to each other, and this connection point is connected to the other end of the load.

In a third aspect of the present invention, in the rectifier circuit of the first or second aspect, a DC reactor is inserted between one terminal of the load and the main circuit. .

According to the present invention, the electrolytic capacitor for smoothing provided in the above-mentioned conventional rectifier circuit is not required, and the number of power conversion stages can be reduced to one, thereby improving the conversion efficiency of the rectifier circuit.

[0012]

FIG. 1 is a diagram showing a main circuit configuration of a rectifier circuit according to a first embodiment of the present invention. Components having the same functions as those of the conventional circuit shown in FIG. It is attached. In other words, the rectifier circuit 10 shown in FIG. 1 is formed by connecting an IGBT (reference symbols Q _{1 to} Q ₁₂ ) and diodes (reference symbols D _{1 to} D ₁₂ ) as self-extinguishing elements in antiparallel, respectively. As shown, a first main circuit 11 and a second main circuit 11 are connected in a full bridge configuration.
The main circuit 12, the third main circuit 13, a capacitor C ₁ -C ₃
, AC reactors L _{1 to} L ₃ , and DC reactor L _O
And

In the rectifier circuit 10, a three-phase AC power source 1 is connected to terminals R, S, and T by a control circuit (not shown).
IGBTs Q _{1 to} Q ₁ according to the phase of the voltage applied from
_{12 The} DC voltage supplied to the load 5 from the terminals P and N is set to a value lower or higher than the full-wave rectified voltage value of the three-phase AC power supply 1 by controlling ON / OFF of each of them in an arbitrary combination. Can be.

For example, a terminal R, a terminal
Voltage V applied to each of S and terminal T_R, V_S, V_T
V between_R> V_T> V_SWhen the relationship is
TQ_ThreeIs turned on, the terminal R → L₁→ D₁→ Q_Three→
L_O→ Terminal P → Load 5 → Terminal N → D₆→ L_Two→ of terminal S
Voltage V between terminal R and terminal S in the path_RSIs applied to the load 5.
be able to. Also, IGBTQ_ThreeWith IG turned on
BTQ_TenIs turned on, the terminal T of the above-described intermediate potential
Terminal T → L_Three→ Q_Ten→ D₆→ L_Two→ Terminal S, or
Terminal R → L₁→ D₁→ Q_Three→ L_O→ Terminal P → Load 5 → End
Child N → D_Ten→ L_Three→ The current can flow through the path of terminal T.
Wear. Next, IGBTQ_ThreeIs turned off, D _Four, D₈,
D₁₂Becomes conductive, load 5 → terminal N → D_Four(D₈, D₁₂)
→ L_O→ Form a reflux mode through the path of terminal P → load 5
You.

The above operation is performed by the control circuit.
Terminals R, depending on the terminal S, the voltage of the phase to be applied from the three-phase AC power source 1 to the terminal T, by the IGBTQ ₁ ~Q ₁₂ in their appropriate frequency modulated on-off period,
The DC voltage supplied from the terminals P and N to the load 5 can be set to a value lower than the full-wave rectified voltage value of the three-phase AC power supply 1 while controlling the current from the three-phase AC power supply 1 in a substantially sinusoidal manner. it can.

A terminal R, a terminal R
Voltage V applied to each of S and terminal T_R, V_S, V_T
V between_R> V_T> V_SIGBT
Q_TwoIs turned on, the terminal R → L₁→ Q_Two→ D₆→ L_Two→
Terminal S and terminal R → L₁→ Q_Two→ D_Ten→ L_Three→ terminal
In the path of T, the current corresponding to the potential difference of each phase is L₁, L_Two, L
_ThreeTo the short-circuit mode via the
Fruit, L₁, L_Two, L_ThreeStores energy. Next
And IGBTQ_TwoAnd turn off the IGBTQ_ThreeTurn on
And terminal R → L₁→ D₁→ Q_Three→ L_O→ Terminal P → Load 5
→ Terminal N → D₆→ L _Two→ Terminal S path and terminal R →
L₁→ D₁→ Q_Three→ L_O→ Terminal P → Load 5 → Terminal N → D
_Ten→ L_Three→ L on the path of terminal T₁, L_Two, L_ThreeD stored in
Energy is supplied to the load 5.

The above operation is performed by the control circuit.
Terminals R, depending on the terminal S, the voltage of the phase to be applied from the three-phase AC power source 1 to the terminal T, by the IGBTQ ₁ ~Q ₁₂ in their appropriate frequency modulated on-off period,
The DC voltage supplied from the terminals P and N to the load 5 can be made higher than the full-wave rectified voltage value of the three-phase AC power supply 1 while controlling the current from the three-phase AC power supply 1 in a substantially sinusoidal manner. it can.

Further, power is supplied from the load 5 to the three-phase AC power supply 1.
If you want to regenerate, for example, IGBTQ_Four, Q₈, Q
₁₂Turn on each, load 5 → terminal P → L_O→ Q_Four
(Q ₈, Q₁₂) → terminal N → load 5 L_OTo Enel
Store ghee. Next, IGBTQ_Four, Q₈, Q₁₂Each
Off the IGBTQ₁, Q₆Is turned on, L
_OThe energy stored in the load 5 → terminal P → L_O→ D_Three→
Q₁→ L₁→ Terminal R → Three-phase AC power supply 1 → Terminal S → L_Two→
Q₆→ Regeneration operation is performed in the route from terminal N to load 5.
Can be.

In the rectifier circuit 10 shown in FIG. 1, each of the capacitors C _1, C _{2, and} C ₃ is not intended for smoothing a DC voltage.
It is a non-polar capacitor having a very small capacity for absorbing the energy of the wiring inductance accompanying the switching operation of each of the main circuit 12 and the third main circuit 13.

FIG. 2 is a diagram showing a main circuit configuration of a rectifier circuit according to a second embodiment of the present invention, in which components having the same functions as those of the embodiment circuit shown in FIG. . That is, the rectifier circuit 20 shown in FIG. 2 is formed by connecting an IGBT (reference symbols Q _{1 to} Q ₁₂ ) and diodes (reference symbols D _{1 to} D ₁₂ ) as self-extinguishing elements in anti-parallel, respectively. As shown, a first main circuit 21 and a second main circuit 2 are connected in a full bridge configuration.
2, the third main circuit 23, and a capacitor C ₁ -C _3, and AC reactors L ₁ ~L _3, and a DC reactor L _O.

In the rectifier circuit 20, a three-phase AC power source 1 is connected to terminals R, S, and T by a control circuit (not shown).
IGBTs Q _{1 to} Q ₁ according to the phase of the voltage applied from
_{12 The} DC voltage supplied to the load 5 from the terminals P and N is set to a value lower or higher than the full-wave rectified voltage value of the three-phase AC power supply 1 by controlling ON / OFF of each of them in an arbitrary combination. Can be.

For example, a terminal R, a terminal
Voltage V applied to each of S and terminal T_R, V_S, V_T
V between_R> V_T> V_SWhen the relationship is
TQ₈Is turned on, the terminal R → L₁→ D₁→ L_O→
Terminal P → Load 5 → Terminal N → Q₈→ D₆→ L_Two→ of terminal S
Voltage V between terminal R and terminal S in the path_RSIs applied to the load 5.
be able to. Also, IGBTQ₈With IG turned on
BTQ_Ten, Q₁₂Is turned on, the end of the aforementioned intermediate potential
Terminal T → L to child T_Three→ Q_Ten→ D₁₂→ Q₈→ D₆→ L_Two
→ Terminal S or Terminal R → L₁→ D₁→ L_O→ Terminal P →
Load 5 → Terminal N → Q₁₂→ D_Ten→ L_Three→ Electricity in the path of terminal T
The current can flow. Next, IGBTQ ₈Turn off
And D_Three, D₇, D₁₁Becomes conductive, load 5 → terminal N → D
_Three(D₇, D₁₁) → L_O→ Terminal P → Return by load 5
Form mode.

The above operation is performed by the control circuit.
Terminals R, depending on the terminal S, the voltage of the phase to be applied from the three-phase AC power source 1 to the terminal T, by the IGBTQ ₁ ~Q ₁₂ in their appropriate frequency modulated on-off period,
The DC voltage supplied from the terminals P and N to the load 5 can be set to a value lower than the full-wave rectified voltage value of the three-phase AC power supply 1 while controlling the current from the three-phase AC power supply 1 in a substantially sinusoidal manner. it can.

Further, a terminal R, a terminal
Voltage V applied to each of S and terminal T_R, V_S, V_T
V between_R> V_T> V_SIGBT
Q_FiveIs turned on, the terminal R → L₁→ D₁→ Q_Five→ L_Two→
Terminal S and terminal T → L_Three→ D₉→ Q_Five→ L_Two→ terminal
In the path of S, the current corresponding to the potential difference of each phase is L₁, L_Two, L
_ThreeTo the short-circuit mode via the
Fruit, L₁, L_Two, L_ThreeStores energy. Next
And IGBTQ_FiveAnd turn off the IGBTQ₈Turn on
And terminal R → L₁→ D₁→ L_O→ Terminal P → Load 5 → Terminal
N → Q₈→ D₆→ L _Two→ Path of terminal S and terminal T →
L_Three→ D₉→ L_O→ Terminal P → Load 5 → Terminal N → Q₈→ D
₆→ L_Two→ L on the path of terminal S₁, L_Two, L_ThreeD stored in
Energy is supplied to the load 5.

The above operation is performed by the control circuit.
Terminals R, depending on the terminal S, the voltage of the phase to be applied from the three-phase AC power source 1 to the terminal T, by the IGBTQ ₁ ~Q ₁₂ in their appropriate frequency modulated on-off period,
The DC voltage supplied from the terminals P and N to the load 5 can be made higher than the full-wave rectified voltage value of the three-phase AC power supply 1 while controlling the current from the three-phase AC power supply 1 in a substantially sinusoidal manner. it can.

Further, power is supplied from the load 5 to the three-phase AC power supply 1.
If you want to regenerate, for example, IGBTQ_Three, Q₇, Q
₁₁Turn on each, load 5 → terminal P → L_O→ Q_Three
(Q ₇, Q₁₁) → terminal N → load 5 L_OTo Enel
Store ghee. Next, IGBTQ_Three, Q₇, Q₁₁Each
Off the IGBTQ₁, Q₆Is turned on, L
_OThe energy stored in the load 5 → terminal P → L_O→ Q₁→
L₁→ Terminal R → Three-phase AC power supply 1 → Terminal S → L_Two→ Q₆→
D₈→ Regeneration operation is performed in the route from terminal N to load 5.
Can be.

In the rectifier circuit 20 shown in FIG. 2, each of the capacitors C _1, C _{2, and} C ₃ is not intended for smoothing a DC voltage.
It is a non-polar capacitor having a very small capacity for absorbing the energy of the wiring inductance accompanying the switching operation of each of the main circuit 22 and the third main circuit 23.

FIG. 3 is a diagram showing the main circuit configuration of a rectifier circuit according to a third embodiment of the present invention. Components having the same functions as those of the embodiment shown in FIG. 1 are denoted by the same reference numerals. . That is, the rectifier circuit 30 shown in FIG. 3 includes IGBTs (reference numerals Q _{1 to} Q ₃ , Q _{5 to} Q ₇ ,
Q _{9 to} Q ₁₁ ) and diodes (reference signs D _{1 to} D ₃ , D ₅
And 9 sets of switching circuits to D _7, D ₉ to D ₁₁₎ and is formed by anti-parallel connected, diodes D _4, a diode D _8, and a diode D _12, as illustrated, full bridge First main circuit 31 and second main circuit 3 connected to configuration
2, the third main circuit 33, and a capacitor C ₁ -C _3, and AC reactors L ₁ ~L _3, and a DC reactor L _O.

The rectifier circuit 30 differs from the rectifier circuit 10 shown in FIG. 1 in that the IGBTQ ₄ in the first main circuit is omitted, the IGBTQ ₈ in the second main circuit is omitted, and the IGBTQ ₁₂ in the third main circuit is omitted. Is omitted, and as a result, power cannot be regenerated from the load 5 to the three-phase AC power supply 1. However, in this rectifier circuit 30, a control circuit (not shown) According to the phase of the voltage applied from the three-phase AC power supply 1 to the terminals R, S, and T, the IGBTs Q _{1 to} Q ₃ ,
_{Q 5 ~Q 7, Q 9 ~Q} 11 to control on and off respectively in any combination, load terminal P, the terminal N 5
Can be made lower or higher than the full-wave rectified voltage value of the three-phase AC power supply 1.

In the rectifier circuit 30 shown in FIG. 3, the capacitors C _1, C _{2, and} C ₃ are not intended for smoothing the DC voltage, but for the first main circuit 31 and the second main circuit 31.
It is a non-polarity capacitor having a very small capacity for absorbing the energy of the wiring inductance accompanying the switching operation of each of the main circuit 32 and the third main circuit 33.

FIG. 4 is a diagram showing a main circuit configuration of a rectifier circuit according to a fourth embodiment of the present invention. Components having the same functions as those of the circuit shown in FIG. 2 are denoted by the same reference numerals. . That is, the rectifier circuit 30 shown in FIG. 4 includes IGBTs (reference numerals Q ₁ , Q ₂ , Q ₄ , Q ₅ ,
Q ₆ , Q ₈ , Q ₉ , Q ₁₀ , Q ₁₂ ) and diodes (references D ₁ , D ₂ , D ₄ , D ₅ , D ₆ , D ₈ , D ₉ , D ₁₀ ,
D ₁₂ ) are connected in anti-parallel to each other, nine sets of switch circuits, a diode D ₃ , a diode D ₇ ,
And diodes D _11, as illustrated, the first main circuit 41 connected to the full bridge configuration, the second main circuit 42, the third main circuit 43, a capacitor C ₁ -C _3, AC reactors L ₁
To L ₃ and a DC reactor L _O.

The rectifier circuit 40 differs from the rectifier circuit 20 shown in FIG. 2 in that the IGBTQ ₃ in the first main circuit is omitted, the IGBTQ ₇ in the second main circuit is omitted, and the IGBTQ ₁₁ in the third main circuit is omitted. Is omitted, and as a result, power cannot be regenerated from the load 5 to the three-phase AC power supply 1. However, in the rectifier circuit 30, a control circuit (not shown) The IGBTs Q ₁ , Q ₂ , Q ₂ ,.
By controlling ON / OFF of Q ₄ , Q ₅ , Q ₆ , Q ₈ , Q ₉ , Q ₁₀ , and Q ₁₂ in an arbitrary combination, the terminal P and the terminal N
Can be set to a value lower or higher than the full-wave rectified voltage value of the three-phase AC power supply 1.

In the rectifier circuit 40 shown in FIG. 4, the capacitors C _1, C _{2, and} C ₃ are not intended for smoothing the DC voltage, but for the first main circuit 41 and the second main circuit 41.
It is a non-polar capacitor having a very small capacity for absorbing the energy of the wiring inductance accompanying the switching operation of the main circuit 42 and the third main circuit 43.

[0034]

According to the rectifier circuit of the present invention, the smoothing electrolytic capacitor, which is a regular replacement component provided in the conventional rectifier circuit, is not required, and as a result, the maintenance and inspection work is simplified. In this rectifier circuit, the number of power conversion stages is also one.
Stage to improve the conversion efficiency of the rectifier circuit.

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 5 is a circuit configuration diagram showing a conventional example.

FIG. 6 is a circuit configuration diagram showing another conventional example different from FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Three-phase AC power supply, 2 ... Diode rectifier, 3 ... Electrolytic capacitor, 4 ... DC chopper circuit, 5 ... Load, 6 ... Self-excited rectifier, 10 ... Rectifier circuit, 11 ... First main circuit, 12 ...
Second main circuit, 13: third main circuit, 20: rectifier circuit, 21
... first main circuit, 22 ... second main circuit, 23 ... third main circuit,
30 rectifier circuit, 31 first main circuit, 32 second main circuit, 33 third main circuit, 40 rectifier circuit, 41 first main circuit, 42 second main circuit, 43 third main circuit circuit, Q ₁ ~Q
_{12 ... IGBT, D 1 ~D 12} ... diodes, C ₁ ~C ₃ ...
Capacitor, L ₁ ~L ₃ ... AC reactors, L _O ... DC reactor.

Claims (3)

[Claims] 1. A switch circuit comprising: a first switch circuit to a twelfth switch circuit formed by connecting a self-extinguishing element and a diode in anti-parallel; and a first bridge circuit to a fourth switch circuit in a full bridge configuration. The first main circuit is connected to the fifth switch circuit to the eighth switch circuit in a full bridge configuration to form a second main circuit, and the ninth to twelfth switch circuits are connected to a full bridge configuration. And a middle connection point between one of the upper and lower arms of the first main circuit is connected to the first phase of the three-phase AC power supply directly or via the first AC reactor. The intermediate connection point of the upper and lower arms is connected to the second phase of the three-phase AC power supply directly or via the second AC reactor, and the intermediate connection point of the upper and lower arms of one of the third main circuits is connected directly or 3rd AC React Via Le connected to the third phase of the three-phase AC power supply, on the other the first main circuit, the intermediate connection point of the lower arm,
An intermediate connection point between the upper and lower arms of the other of the second main circuit;
The other upper end of the third main circuit and the intermediate connection point of the lower arm are connected to each other, this connection point is connected to one end of a load, and the upper arm side connection from the first main circuit to the third main circuit. A rectifier circuit comprising: connecting a point or a lower arm side connection point to each other; and connecting the connection point to the other end of the load. 2. A first to ninth switch circuit formed by connecting a self-extinguishing element and a diode in anti-parallel, a first diode, a second diode, and a third switch circuit.
A first switch circuit from a third switch circuit to a third switch circuit and a first diode connected in a full bridge configuration to form a first main circuit; a fourth switch circuit to a sixth switch circuit; and a second diode Are connected in a full bridge configuration to form a second main circuit, and the seventh to ninth switch circuits and the third diode are connected in a full bridge configuration to form a third main circuit. An intermediate connection point between the upper and lower arms of only the switch circuit is connected to the first phase of the three-phase AC power supply directly or via the first AC reactor, and only the upper and lower arms of the switch circuit of the second main circuit are connected. An intermediate connection point is connected to the second phase of the three-phase AC power supply directly or via a second AC reactor, and an intermediate connection point between the upper and lower arms of only the switch circuit of the third main circuit is directly or thirdly connected. Via a flow reactor connected to the third phase of the three-phase AC power supply, on the other the first main circuit, the intermediate connection point of the lower arm,
An intermediate connection point between the upper and lower arms of the other of the second main circuit;
The other upper end of the third main circuit and the intermediate connection point of the lower arm are connected to each other, this connection point is connected to one end of a load, and the upper arm side connection from the first main circuit to the third main circuit. A rectifier circuit comprising: connecting a point or a lower arm side connection point to each other; and connecting the connection point to the other end of the load. 3. The rectifier circuit according to claim 1, wherein a DC reactor is inserted between one terminal of the load and the main circuit.