JP3374958B2 - Power conversion circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention obtains an AC voltage of a desired magnitude and frequency by a voltage source inverter, and
The present invention relates to a power conversion circuit that can control an input current of a rectifier circuit in a sine wave shape when an AC power source and a rectifier circuit are used in combination as a DC power source.

[0002]

2. Description of the Related Art FIG. 10 shows a conventional three-phase output power conversion circuit, in which 101 is a single-phase AC power supply,
Reference numeral 201 is a single-phase full-wave rectification circuit composed of a diode bridge, 301 is a reactor, 401 is a step-up chopper composed of a semiconductor switching element Tr7 and a diode D1 in which diodes are connected in antiparallel, 501 is a smoothing capacitor, and 601 is a diode. A three-phase voltage source inverter 701 including semiconductor switching elements Tr1 to Tr6 connected in anti-parallel is a load such as a three-phase AC motor.

In this prior art, the step-up chopper 401 is used for the purpose of obtaining a DC voltage to be supplied to the inverter 601 and making the input current waveform from the AC power source 101 a sine wave. That is, by turning on the switching element Tr7, the energy of the AC power supply 101 is stored in the reactor 301, and by turning off the switching element Tr7, the energy stored in the reactor 301 is stored in the smoothing capacitor 501 together with the energy supplied from the AC power supply 101. Supply to. As a result, by appropriately performing the switching operation of the switching element Tr7, the input current can be a sine wave synchronized with the power supply voltage.

On the other hand, the inverter 601 is a three-phase voltage type PWM inverter which uses the DC voltage of the smoothing capacitor 501 as an input voltage and which is provided with self-extinguishing type semiconductor switching devices Tr1 to Tr6 such as IGBTs in three sets of upper and lower arms. is there. The operation of the three-phase voltage-type PWM inverter is well known, so the description thereof will be omitted. However, six switching patterns for controlling the three-phase line voltages by controlling the conduction states of the six arms and the upper arm or It is possible to select two types of switching patterns, so-called zero voltage vectors, in which all the lower arms are made conductive so that the three-phase line voltages are all zero. Note that by setting the capacity of the smoothing capacitor 501 sufficiently large, the switching of the boost chopper 201 and the inverter 601 can be performed independently and freely.

[0005]

In the configuration of FIG. 10, the step-up chopper 401 and the inverter 601 are combined, and seven self-extinguishing type semiconductor switching elements are required.
If these drive circuits, drive power supplies, control circuits, etc. are included, the circuit configuration becomes complicated and expensive. Further, since the boost chopper 401 has a great responsibility for the self-extinguishing type semiconductor switching element Tr7, the switching loss increases.
This is an obstacle to the miniaturization of the device.

Therefore, the present invention reduces the semiconductor switching elements used to simplify the circuit structure, downsize the device, and reduce the cost, and control the input current in a sinusoidal shape as required. It is intended to provide a power conversion circuit in which the DC voltage of an inverter is variable.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is a DC power supply and a voltage supplied to a load by converting the power of the DC power supply into AC power by the operation of a semiconductor switching element. Type inverter and a power converter circuit. And, the feature is that a zero-phase flow means comprising a plurality of diodes having the same polarity and having one ends commonly connected is provided, and the zero-phase flow means is connected between the DC power supply and each phase AC output terminal of the inverter. At the same time, the switching pattern of the inverter is selected by time division so that the inverter exchanges AC power with the load, and at the time of outputting the zero voltage vector by the inverter, the inverter is connected to the DC power source through the zero-phase flow means. Zero-phase power is transmitted and received between them.

Here, FIG. 1 is a conceptual diagram of the invention described in claim 1. In the figure, 100 is a single-phase or multi-phase AC power supply, 200 is a rectifying means such as a full-wave rectifying circuit for converting AC into DC, and 150 is an AC power supply 100 and rectifying means 2.
A DC power source composed of 00, 600 is a voltage inverter, for example, a three-phase voltage source that converts power by the operation of a semiconductor switching element and outputs an AC voltage, 700 is a load such as an AC motor, 800 is a DC output terminal of the rectifying means 200, It is a zero-phase flow means composed of a diode connected to the AC output terminal of the voltage source inverter 600. Here, when the zero voltage vector is output by the voltage source inverter 600, the output voltage of the rectifying means 200 (DC power supply 150) is
The presence of the diode group of the zero-phase flow means 800 between the AC output terminal of the inverter 600 (the input terminal of the load 700) causes a so-called zero-phase voltage, and the zero-phase current of the zero-phase flow means 800 becomes. It is bypassed by the diode group and does not flow to the load 700. At this time, the voltage source inverter 600 can be regarded as one arm that performs switching operation at the ratio of the zero voltage vector, and operates similarly to the step-up chopper 401 shown in the related art of FIG. Therefore, it is not necessary to separately provide a boost chopper, and it is possible to reduce the number of semiconductor switching elements in the entire circuit and to omit the drive circuit, drive power supply, control circuit, and the like. When the voltage-type inverter 600 is a single-phase voltage-type inverter, the zero voltage vector is output by making all the two sets of upper arms conductive or making the two sets of lower arms conductive.

The following inventions are obtained by further embodying the invention described in claim 1 and applied to a three-phase output power conversion circuit. First, the invention according to claim 2 is a DC power supply comprising an AC power supply and a rectifier circuit connected to this AC power supply, and the operation of a semiconductor switching element converts the power of the DC power supply into three-phase AC power and supplies it to a load. The present invention relates to a power conversion circuit including a three-phase voltage source inverter. The feature is that a zero-phase bypass diode is provided as a zero-phase flow means composed of three diodes whose anodes are commonly connected, and the anode is connected to the positive side output terminal of the rectifier circuit via a reactor, Each cathode of each diode is connected to each phase AC output terminal of the inverter, and the negative side output terminal of the rectifier circuit is connected to the negative side terminal of the smoothing capacitor on the DC input side of the inverter. The AC power is exchanged with the load, and the zero-phase power is exchanged with the AC power supply via the zero-phase bypass diode when the inverter outputs the zero-voltage vector.

According to a third aspect of the invention, in the second aspect of the invention, one end of the reactor is connected to the negative side output terminal of the rectifier circuit, and the polarity of the zero-phase bypass diode is reversed accordingly. . That is, the feature is that a zero-phase bypass diode is provided as a zero-phase flow means composed of three diodes whose cathodes are commonly connected, and the cathode is connected to the negative side output terminal of the rectifier circuit via a reactor, Each anode of each diode is connected to each phase AC output terminal of the inverter, and the positive side output terminal of the rectifier circuit is connected to the positive side terminal of the smoothing capacitor on the DC input side of the inverter. The AC power is exchanged with the load, and the zero-phase power is exchanged with the AC power supply via the zero-phase bypass diode when the inverter outputs the zero-voltage vector.

According to a fourth aspect of the invention, the reactor according to the second aspect of the invention is connected between an AC power source and a rectifying circuit. That is, the feature is that a DC power supply including an AC power supply and a rectifier circuit connected to this AC power supply through a reactor, and the operation of the semiconductor switching element convert the power of the DC power supply into three-phase AC power and supply it to the load. In a power conversion circuit including a three-phase voltage source inverter, a zero-phase bypass diode is provided as a zero-phase current-passing means composed of three diodes whose anodes are commonly connected, and the anode is connected to the positive side output terminal of the rectifier circuit. Connect each cathode of the three diodes to each phase AC output terminal of the inverter, and connect the negative side output terminal of the rectifier circuit to the negative side terminal of the smoothing capacitor on the DC input side of the inverter. Causes the inverter to transfer AC power to and from the load, and at the time of output of the zero voltage vector by the inverter, AC It is to exchange the zero-phase power to and from the source.

According to a fifth aspect of the present invention, the polarity of the zero-phase bypass diode in the fourth aspect is reversed as in the third aspect of the invention with respect to the second aspect of the invention. That is, the feature is that a zero-phase bypass diode is provided as a zero-phase current flowing means composed of three diodes whose cathodes are commonly connected, the cathode is connected to the negative side output terminal of the rectifier circuit, and each of the three diodes is connected. Connect the anode to each phase AC output terminal of the inverter, and connect the positive side output terminal of the rectifier circuit to the positive side terminal of the smoothing capacitor on the DC input side of the inverter. AC power is transmitted and received at the same time, and zero phase power is exchanged with the AC power supply when the zero voltage vector is output by the inverter.

According to a sixth aspect of the present invention, the combination of the AC power supply and the rectifier circuit is replaced with a DC power supply, and a zero voltage vector is output to the inverter to make the DC input voltage of the inverter variable. That is, the feature is that the anode is common in the power conversion circuit including the DC power supply and the three-phase voltage source inverter that converts the power of the DC power supply into the three-phase AC power by the operation of the semiconductor switching element and supplies it to the load. A zero-phase bypass diode composed of three connected diodes is provided as a zero-phase flow means, the anode is connected to the positive electrode of the DC power source through the reactor, and the cathodes of the three diodes are respectively connected to the alternating-current phases of the inverter. In addition to connecting to the output terminal, connect the negative electrode of the DC power supply to the negative terminal of the smoothing capacitor on the DC input side of the inverter, and by time division, the inverter will transfer AC power to and from the load, and When the zero voltage vector is output, the inverter controls the DC voltage of the inverter by exchanging zero-phase power with the DC power supply. Is shall.

According to a seventh aspect of the present invention, as in the third aspect of the invention with respect to the second aspect of the invention, or the fifth aspect of the invention with respect to the fourth aspect, the polarity of the zero-phase bypass diode in the sixth aspect is reversed. It was made. That is, the feature is that a zero-phase bypass diode is provided as a zero-phase current-passing means composed of three diodes whose cathodes are commonly connected, and the cathode is connected to the negative electrode of the DC power source through the reactor, and the three diodes Connect each anode to each phase AC output terminal of the inverter, and connect the positive pole of the DC power supply to the positive side terminal of the smoothing capacitor on the DC input side of the inverter. The inverter controls the DC voltage of the inverter by exchanging electric power and by exchanging zero-phase electric power with the DC power source when the inverter outputs a zero voltage vector.

The invention according to claim 8 is characterized by means for calculating a zero-phase voltage command value to be superimposed on each phase voltage command value. That is, in the power conversion circuit according to claim 2, 4 or 6, the zero-phase voltage command value superimposed on each phase voltage command value is a deviation between the zero-phase (input) current command value and the zero-phase current detection value. The value is obtained by subtracting the minimum value of each phase voltage command value from the anode potential command value of the zero-phase bypass diode obtained by inputting to the current controller.

The invention according to claim 9 is also characterized in the calculation means of the zero-phase voltage command value to be superimposed on each phase voltage command value. That is, in the power conversion circuit according to claim 3, 5 or 7, the zero-phase voltage command value superimposed on each phase voltage command value is a deviation between the zero-phase (input) current command value and the zero-phase current detection value. The value is obtained by subtracting the maximum value of each phase voltage command value from the cathode potential command value of the zero-phase bypass diode obtained by inputting to the current controller.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 2 is a circuit diagram showing an embodiment of the invention described in claim 2. In the figure, as in FIG. 10, 101 is a single-phase AC power supply, 201 is a single-phase full-wave rectifier circuit consisting of a diode bridge, 301 is a reactor, 5
Reference numeral 01 is a smoothing capacitor, 601 is a three-phase voltage source inverter composed of semiconductor switching elements Tr1 to Tr6 in which diodes are connected in antiparallel, and 701 is a load such as a three-phase AC motor. In this embodiment, the boost chopper 401 in FIG. 10 is not provided. Instead, the diodes D11, D12, D13 are connected in parallel for each phase between one end of the reactor 301 on the side of the inverter 601 and the three-phase AC output terminals U, V, W of the inverter 601 with the same polarity ( A zero-phase bypass diode 801 is provided as a zero-phase flow means, in which each anode is commonly connected to the reactor 301 and each cathode is connected to the three-phase AC output terminals U, V, and W). Further, in the present embodiment, the negative side terminal of the inverter 601 (smoothing capacitor 501) is connected to the negative side output terminal of the rectifier circuit 201.

In this embodiment, a three-phase voltage source inverter 60 is used.
It focuses on the zero voltage vector of 1. That is,
In order to output a zero voltage vector in the three-phase voltage source inverter 601, there are two switching patterns, that is, the case where all the upper arms are made conductive and the case where all the lower arms are made conductive. In this embodiment, this degree of freedom is utilized. .
Since the zero-phase voltage output from the inverter 601 does not appear in the line voltage, it does not affect the power supply to the load 701. Therefore, the equivalent circuit for the positive phase is as shown in FIG. 3, and the power supply to the load 701 operates as the same inverter as the conventional one, and the load is controlled by controlling the power between the line voltage of the inverter 601 and the current flowing between the lines. AC power is exchanged with 701.

On the other hand, when considering the zero-phase component, it becomes as shown in FIG. 4, and the three arms of the inverter 601 in FIG. 2 can be regarded as one arm 601 ′ which performs switching operation at the ratio of the zero voltage vector. That is, the switching elements Tr1 and T of the upper arm of the inverter 601 are
By turning on all of r3 and Tr5 or all of the switching elements Tr2, Tr4 and Tr6 of the lower arm to output a zero voltage vector, the boost chopper 401 shown in FIG. 10 can be substituted. By the zero-phase voltage control operation by the inverter 601, it is possible to control the current waveform of the AC power supply 101 in a sine wave shape synchronized with the power supply voltage, as in the conventional case. Note that FIG.
D10 in the zero-phase equivalent circuit is a diode equivalently showing the zero-phase bypass diode 801 in FIG.

That is, if a zero-phase bypass diode 801 is connected between one end of the reactor 301 and each phase AC output terminal of the inverter 601, a zero-voltage vector is output to the inverter 601 to control the zero-phase voltage, the equivalent is obtained. Specifically, the circuit of FIG. 4 is configured. At this time, the output voltage of the rectifier circuit 201 is the input terminal of the load 701, that is, the inverter 6
See 01 of each phase AC output terminals when become zero-phase voltage and, as shown in FIG. 4, the zero-phase current i ₀ is the diode D1
It is bypassed by 0 (zero-phase bypass diode 801) and does not flow to the load 701. In this way, when the zero-voltage vector is output by the inverter 601, the zero-phase power is transmitted and received between the single-phase AC power supply 101 and the inverter 601 via the zero-phase bypass diode 801, so that the same operation as the conventional boost chopper 401 is performed. Therefore, it is possible to reduce the number of semiconductor switching elements, their driving circuits, and the like when viewed from the overall power conversion circuit. Therefore, the circuit configuration can be simplified, downsized, and reduced in cost.

The inverter 601 in FIG. 2 is PWM-controlled, and its PWM pulse is generated by the control circuit shown in FIG. 5, for example. This control circuit corresponds to the embodiment of the invention of claim 8. That is, in FIG. 5, the deviation between the DC voltage command value v _dc ^* and the DC voltage detection value v _dc (voltage of the smoothing capacitor 501 in FIG. 2) is determined by the voltage controller 9
Input to 01, and its output is in phase with power supply voltage and size is 1
The absolute value of the sine wave | sinω _s t | obtain zero phase by multiplying by the multiplier 902 (input) current command value i ₀ ^* a. In addition, the deviation between the zero-phase current command value i ₀ ^* and the zero-phase current detection value i ₀ is input to the current controller 903, and the zero-phase bypass diode output from the controller 903 is output as shown in Equation 2 below. 801
The difference between the anode potential command value v _an ^* and the output of the minimum value circuit 904 is defined as the zero-phase voltage command value v ₀ ^* . The minimum value circuit 904 is a circuit that outputs the minimum value of the phase voltage command values v _a ^* , v _b ^* , and v _c ^* . Furthermore, the zero-phase voltage command value v
₀ ^* is the phase voltage command values ^{_{v a *, v b *,}} v c * and are added respectively are input to the comparator 905 to 907, it is compared with the triangular wave. By inverting the outputs of these comparators 905 to 907 by the upper and lower arms, the inverter 6
PWM for switching elements Tr1 to Tr6 of 01
Get the pattern.

[0022] Here, the anode potential v _an the zero-phase bypass diode 801, one of the switching elements Tr2 in the lower arm of inverter 601, Tr4, Tr6 becomes is turned on zero. Considering the average voltage of one switching cycle, the anode potential _van is the lowest potential of the average voltage of each switching cycle of the U, V, and W phases. Therefore, the anode potential v _an is the phase voltage command value is calculated from the voltage command value between the phases of the line v _a ^*, v _b ^*, v _c ^* and the zero-phase voltage command value v based on ₀ ^* and, It is expressed by Equation 1. ^{_{Here, min (v a *, v}} b *, v c *) is ^{_{v a *, v b *,}} v c * indicates the minimum value of the output of said minimum value circuit 904.

[0023]

[Number 1] ^{_{v an = min (v a *}} , v b *, v c *) + v 0 *

Therefore, each phase voltage command value v _a ^* , v _b ^* , v _c ^*
The zero-phase voltage command value v ₀ ^* superimposed on is expressed by Formula 2 when the anode potential command value is v _an ^* .

[0025]

[Number 2] _{^{v 0 * = v an * -min}} (v a *, v b *, v c *)

Next, FIG. 6 is a circuit diagram showing an embodiment of the invention described in claim 3. In this embodiment, the positive side output terminal of the rectifier circuit 201 and the positive side terminal of the smoothing capacitor are connected, one end of the reactor 301 is connected to the negative side output terminal of the rectifier circuit 201, and the other end and the inverter 601. A zero-phase bypass diode 802 is connected between the AC output terminals U, V, and W. Along with this, the polarities of the diodes D11 to D13 forming the zero-phase bypass diode 802 are reversed from those in FIG.

In this embodiment also, the inverter 60
When the zero-voltage vector is output by 1, the single-phase AC power supply 101
The zero-phase bypass diode 8 between the inverter and the inverter 601.
By transmitting and receiving zero-phase power via 02, the inverter 601 is caused to perform the same operation as the conventional boost chopper,
The semiconductor switching element for the step-up chopper, its drive circuit, etc. can be omitted.

FIG. 7 shows a control circuit for the inverter 601 shown in FIG. 6, which corresponds to the ninth embodiment of the invention. 5 is different from FIG. 5 in that in the control circuit of FIG. 7, the output of the current controller 903 is the cathode potential command value v _kn ^* of the zero-phase bypass diode 802, while the phase voltage command values v _a ^* and v _b ^{* are set.} , V _c
^A maximum value circuit 908 outputs the maximum value of ^* , and the difference between the two is set as the zero-phase voltage command value v ₀ ^* .

Now, the cathode potential v _kn of the zero-phase bypass diode 802 becomes E [V] (DC input voltage of the inverter 601) when one of the switching elements Tr1, Tr3, Tr5 of the upper arm of the inverter 601 is turned on. . Considering the average voltage of one switching cycle, the cathode potential v _kn is the highest potential of the average voltage of each switching cycle of the U, V, and W phases. Therefore, the cathode potential v _kn is calculated based on the line voltage command values v _a ^* , v _b ^* , v _c ^* and the zero phase voltage command value v ₀ ^* calculated from the line voltage command values of the respective phases. It is expressed by Equation 3. Where max (v
^{_{a *, v b *, v}} c *) is ^{_{v a *, v b *,}} v c * indicates the maximum value of the output of said maximum value circuit 908.

[0030]

[Number 3] ^{_{v kn = max (v a *}} , v b *, v c *) + v 0 *

Therefore, each phase voltage command value v _a ^* , v _b ^* , v _c ^*
The zero-phase voltage command value v ₀ ^* to be superimposed on is expressed by Formula 4 when the cathode potential command value is v _kn ^* .

[0032]

[Number 4] _{^{v 0 * = v kn * -max}} (v a *, v b *, v c *)

FIG. 8 shows an embodiment of the invention described in claim 4, in which the reactor 301 on the DC side in the embodiment of FIG. 2 is replaced with the reactor 302 on the AC side. The operation of this embodiment is similar to that of FIG.
The main circuit including the rectifier circuit 201, the zero-phase bypass diode 801, the inverter 601, and the smoothing capacitor 501 can be modularized to reduce the size of the entire apparatus. As in the present embodiment, the reactor is an AC power supply 101
The idea of connecting to the side is also applicable to the embodiment of FIG. That is, although not shown, the AC power supply 101 and the rectifier circuit 2 are used instead of the reactor 301 on the DC side in FIG.
An AC reactor may be connected to 01. This configuration corresponds to the embodiment of the invention described in claim 5.
Note that the control circuit of the inverter 601 may be the control circuit of FIG. 5 or 7.

Finally, FIG. 9 shows an embodiment of the invention described in claim 6. In this embodiment, the combination of the AC power supply 101 and the rectifier circuit 201 in the embodiment of FIG. 2 is replaced with a DC power supply 151. In the present embodiment, the DC link voltage of the inverter 601 can be increased by causing the inverter 601 to output a zero voltage vector and performing the same operation as the conventional boost chopper.
This allows the output voltage range to be expanded. The idea of using the DC power supply 151 instead of the combination of the AC power supply and the rectifier circuit as in this embodiment can be applied to the embodiment of FIG. 6, and an example thereof is the embodiment of the invention described in claim 7. Equivalent to. Here, the control circuit of the inverter 601 may be the control circuit of FIG. 5 or 7.

The present invention can also be applied to a power conversion circuit equipped with a single-phase voltage source inverter or a multi-phase voltage source inverter other than three-phase.

[0036]

As described above, according to the inventions of claims 1 to 5 and claims 8 and 9, the input current waveform is sinusoidal by controlling the zero phase voltage by causing the inverter to output the zero voltage vector. A converter such as a conventional step-up chopper that controls in a wave pattern can be substituted by an inverter, and the semiconductor switching element of the entire power conversion circuit and its drive circuit, the control power supply, etc. are reduced to simplify the circuit configuration, downsize the device, Low cost and high input power factor can be realized. Also,
According to the sixth and seventh aspects of the invention, the DC power supply voltage can be boosted without adding an arm by utilizing the zero-phase voltage pseudo-obtained by the zero-phase bypass diode. It becomes unnecessary.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a configuration of the invention described in claim 1.

FIG. 2 is a circuit diagram showing an embodiment of the invention described in claim 2.

3 is a positive-phase equivalent circuit of the embodiment of FIG.

4 is a zero-phase equivalent circuit of the embodiment of FIG.

5 is a control circuit diagram of the embodiment of FIG. 2. FIG.

FIG. 6 is a circuit diagram showing an embodiment of the invention described in claim 3.

FIG. 7 is a control circuit diagram of the embodiment of FIG.

FIG. 8 is a circuit diagram showing an embodiment of the invention described in claim 4.

FIG. 9 is a circuit diagram showing an embodiment of the invention described in claim 6;

FIG. 10 is a circuit diagram showing a conventional three-phase output power conversion circuit.

[Explanation of symbols]

100 AC power supply 150 DC power supply 200 Rectification means 600 voltage source inverter 700 load 800 Zero-phase flow means 101 Single-phase AC power supply 151 DC power supply 201 Single-phase full-wave rectifier circuit 301,302 reactor 501 smoothing capacitor 601 Three-phase voltage source inverter 601 'arm 701 load 801,802 Zero-phase bypass diode 901 Voltage controller 902 multiplier 903 Current controller 904 Minimum value circuit 905-907 comparator 908 maximum value circuit Tr1 to Tr6 Self-extinguishing type semiconductor switching element D10 to D13 diodes

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02M 7/5387

Claims (9)

(57) [Claims] 1. A power conversion circuit comprising a DC power supply and a voltage source inverter that converts the power of the DC power supply into AC power by the operation of a semiconductor switching element and supplies the AC power to a load. A zero-phase current flowing means consisting of a plurality of connected diodes is provided, and this zero-phase current flowing means is connected between the DC power supply and each phase AC output terminal of the inverter, and the inverter is connected to the load by time division. AC power is transmitted and received by the inverter, and zero-phase power is exchanged with the DC power source via the zero-phase current flowing means when the zero voltage vector is output by the inverter. 2. A DC power supply comprising an AC power supply and a rectifying circuit connected to this AC power supply, and a three-phase voltage type which converts the power of the DC power supply into three-phase AC power by the operation of a semiconductor switching element and supplies the load to a load. In a power conversion circuit including an inverter, a zero-phase bypass diode is provided as a zero-phase current-flowing means composed of three diodes whose anodes are commonly connected, and the anode is connected to the positive side output terminal of the rectification circuit via a reactor. Then connect each cathode of the three diodes to each phase AC output terminal of the inverter, and connect the negative side output terminal of the rectifier circuit to the negative side terminal of the smoothing capacitor on the DC input side of the inverter. , The inverter transfers AC power to and from the load, and the zero-phase bypass is applied when the inverter outputs the zero voltage vector. A power conversion circuit, which exchanges zero-phase power with an AC power supply via a diode. 3. A DC power supply comprising an AC power supply and a rectifying circuit connected to this AC power supply, and a three-phase voltage type which converts the power of the DC power supply into three-phase AC power by the operation of a semiconductor switching element and supplies it to a load. In a power conversion circuit including an inverter, a zero-phase bypass diode is provided as a zero-phase flow means composed of three diodes whose cathodes are commonly connected, and the cathode is connected to the negative side output terminal of the rectifier circuit via a reactor. Then, connect each anode of the three diodes to each phase AC output terminal of the inverter, and connect the positive output terminal of the rectifier circuit to the positive terminal of the smoothing capacitor on the DC input side of the inverter. , The inverter transfers AC power to and from the load, and the zero-phase bypass is applied when the inverter outputs the zero voltage vector. A power conversion circuit, which exchanges zero-phase power with an AC power supply via a diode. 4. A DC power supply comprising an AC power supply and a rectifier circuit connected to this AC power supply via a reactor, and the power of the DC power supply is converted to three-phase AC power by the operation of a semiconductor switching element and supplied to a load. In a power conversion circuit including a three-phase voltage source inverter, a zero-phase bypass diode is provided as a zero-phase current-flowing means composed of three diodes whose anodes are commonly connected, and the anode is connected to the positive side output terminal of the rectifier circuit. And above 3
Connect each cathode of each diode to each phase AC output terminal of the inverter, and connect the negative side output terminal of the rectifier circuit to the negative side terminal of the smoothing capacitor on the DC input side of the inverter. An electric power conversion circuit, which exchanges AC power with a load and exchanges zero-phase power with an AC power supply when a zero voltage vector is output by an inverter. 5. A DC power supply comprising an AC power supply and a rectifier circuit connected to this AC power supply via a reactor, and the power of the DC power supply is converted into three-phase AC power by the operation of a semiconductor switching element and supplied to a load. In a power conversion circuit provided with a three-phase voltage source inverter, a zero-phase bypass diode is provided as a zero-phase current-passing means composed of three diodes whose cathodes are commonly connected, and the cathode is connected to the negative output terminal of the rectifier circuit. And above 3
Connect each anode of each diode to each phase AC output terminal of the inverter, and connect the positive side output terminal of the rectifier circuit to the positive side terminal of the smoothing capacitor on the DC input side of the inverter. An electric power conversion circuit, which exchanges AC power with a load and exchanges zero-phase power with an AC power supply when a zero voltage vector is output by an inverter. 6. A power conversion circuit comprising a DC power supply and a three-phase voltage source inverter that converts the power of the DC power supply into three-phase AC power by the operation of a semiconductor switching element and supplies the three-phase AC power to a load. A zero-phase bypass diode as a zero-phase current-passing means composed of three diodes is provided, the anode is connected to the positive electrode of the DC power supply through the reactor, and the cathodes of the three diodes are respectively output as alternating current phases of the inverter. Connect the negative terminal of the DC power supply to the negative terminal of the smoothing capacitor on the DC input side of the inverter as well as connect to the terminal.By time division, the inverter transfers AC power to and from the load and Controlling the DC voltage of the inverter by transmitting and receiving zero-phase power with the DC power source when the inverter outputs the voltage vector Power conversion circuit characterized by. 7. A power conversion circuit comprising a DC power supply and a three-phase voltage source inverter which converts the power of the DC power supply into three-phase AC power by the operation of a semiconductor switching element and supplies the three-phase AC power to a load. The cathode is commonly connected. A zero-phase bypass diode as a zero-phase current-passing means composed of three diodes is provided, and the cathode is connected to the negative electrode of the DC power source through the reactor, and the anodes of the three diodes are respectively output as AC outputs of the inverters. Connect the positive terminal of the DC power supply to the positive terminal of the smoothing capacitor on the DC input side of the inverter as well as connect it to the terminal.By time division, the inverter transfers AC power to and from the load and Controlling the DC voltage of the inverter by transmitting and receiving zero-phase power with the DC power source when the inverter outputs the voltage vector Power conversion circuit characterized by. 8. The power conversion circuit according to claim 2, wherein the zero-phase voltage command value to be superimposed on each phase voltage command value is changed from the anode potential command value of the zero-phase bypass diode to each phase voltage command value. A power conversion circuit characterized by having a value obtained by subtracting the minimum value of the above. 9. The power conversion circuit according to claim 3, 5 or 7, wherein the zero-phase voltage command value to be superimposed on each phase voltage command value is changed from the cathode potential command value of the zero-phase bypass diode to each phase voltage command value. A power conversion circuit characterized by having a value obtained by subtracting the maximum value of the above.