JP2924589B2 - Power converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-phase or three-phase power converter for converting an AC voltage into a DC voltage.

[0002]

2. Description of the Related Art A three-phase power converter having a configuration in which a three-phase bridge type conversion circuit is connected to a three-phase AC power supply via a reactor is known as a current tracking type high power factor converter. The power conversion circuit of this device is configured by bridging six switching elements such as IGBTs (insulated gate bipolar transistors) and connecting diodes in anti-parallel to each switching element. This type of power conversion circuit not only converts a three-phase AC voltage to DC, but also has a function of approximating a waveform of an input AC current to a sine wave, a function of bringing a power factor close to 1, and a function of controlling an output voltage to a desired value. Having.

[0003]

In order to control the DC output voltage, the conventional power converter has a DC voltage detector. Accordingly, the cost of the power conversion device is increased and the size thereof is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power converter that can reduce the cost and the size by eliminating the DC output voltage detector.

[0005]

According to a first aspect of the present invention, there is provided a reactor connected in series to at least one of AC power supply lines for supplying a sinusoidal AC voltage. 2u, 2v, the output terminals of the reactors 2u, 2v and a pair of DC output terminals 4, 5
And a bridge circuit including first, second, third, and fourth switching elements Q1 to Q4 connected between the first, second, third, and fourth switching elements Q1 to Q4.
A first, a second, a third, and a fourth diode D1 to D4 connected in antiparallel to Q4;
5, a voltage detector 9 for detecting a voltage Vsu of the AC power supply line 6u, and a current detector 8 for detecting a current Isu of the AC power supply line 6u.
u, a DC voltage command value generating means 18 for generating a DC voltage command value Edr indicating a desired output voltage between the DC output terminals 4 and 5, the voltage detector 9 and the current detector 8u, An estimated DC voltage E between the DC output terminals 4 and 5 based on the voltage Vsu and the current Isu of the AC power supply line.
d ', a voltage control signal corresponding to the difference between the DC voltage command value Edr and the DC voltage estimated value Ed' is created, and a sine wave signal synchronized with the voltage of the AC power supply line and the voltage control signal are generated. A current control signal au corresponding to the difference between the current Isu of the AC power supply line and the current command signal, and a current control signal au obtained from the control means. A PWM (Pulse Width Modulation) pulse for controlling the first to fourth switching elements Q1 to Q4 to be turned on / off based on the above is used to control the first to fourth switching elements Q1 to Q4. The present invention relates to a power converter characterized by comprising a pulse generating means 17. In order to achieve the above object, the invention according to claim 2 provides a three-phase AC power supply line 6 u, 6 u for supplying a sinusoidal three-phase AC voltage.
v, 6w, first, second and third reactors 2u, 2v, 2w connected in series, output terminals of the first, second and third reactors 2u, 2v, 2w and a pair of DC outputs A three-phase bridge circuit comprising first, second, third, fourth, fifth, and sixth switching elements Q1 to Q6 connected between the terminals 4, 5; 3, fourth,
First, second, third, fourth, fifth and sixth diodes D1 to D6 connected in anti-parallel to fifth and sixth switching elements Q1 to Q6, and the pair of DC output terminals 4, 5; A smoothing capacitor 7 connected therebetween, a voltage detector 9 for detecting at least one of the voltages Vsu, Vsv, Vsw of the three-phase AC power supply lines 6u, 6v, 6w, and the three-phase AC power supply line 6u, 6v, 6w currents Isu, Isv, Isw
Current detectors 8u, 8w for detecting at least one of
DC voltage command value generating means 18 for generating a DC voltage command value Edr indicating a desired output voltage of the DC output terminals 4, 5.
And a DC voltage estimated value of the DC output terminals 4 and 5 connected to the voltage detector 9 and the current detectors 8 u and 8 w based on the voltages Vsu and Vsw of the AC power supply line and the currents Isu and Isw. Ed ′ is obtained, a voltage control signal corresponding to the difference between the DC voltage command value Edr and the DC voltage estimated value Ed ′ is created, and a sine wave signal synchronized with the voltage of the AC power supply line and the voltage control signal are generated. , A current control signal au, aw corresponding to the difference between the current Isu, Isw of the AC power supply line and the current command signal, and control means for obtaining the current command signal. PWM for controlling on / off of the first to sixth switching elements Q1 to Q6 based on current control signals au and aw
(Pulse Width Modulation) The present invention relates to a three-phase power converter including a PWM pulse generating means 17 for producing a pulse and controlling the first to sixth switching elements Q1 to Q6.

[0006]

According to the present invention, the DC output voltage is estimated based on the voltage and current of the AC power supply line, so that a voltage detector is not required, and the cost and size of the power converter can be reduced. .

[0007]

First Embodiment Next, a three-phase power converter according to a first embodiment of the present invention will be described with reference to FIGS. In the three-phase power conversion device shown in FIG. 1, a power conversion circuit 3 is connected to a three-phase AC power supply 1 via reactors 2u, 2v, and 2w. The power conversion circuit 3 is configured by connecting the first to sixth switching means in a three-phase bridge. The first to sixth switching means forming the bridge circuit include first to sixth switching elements Q1 to Q6 each formed of an IGBT and first to sixth diodes D1 to D6.
And an anti-parallel circuit. The series circuit of the first and second switching elements Q1, Q2, the series circuit of the third and fourth switching elements Q3, Q4, and the series circuit of the fifth and sixth switching elements Q5, Q6 are a pair. A three-phase AC line is connected between the DC output terminals 4 and 5 and a middle point of the three series circuits. Three-phase AC line 6u, 6
v and 6w include high frequency component removing capacitors C1, C2,
C3 is connected. A smoothing capacitor 7 is connected between the DC output terminals 4 and 5.

In order to control the U-phase and W-phase currents and the DC output voltage, current detectors 8u and 8w are provided for the u-phase and w-phase, respectively, and connected to the u-phase line 6u and the w-phase line 6w. A voltage detector 9 comprising a step-down transformer is provided. The current detectors 8u and 8w and the voltage detector 9 are A / D
Built-in (analog / digital) converter and outputs digital signal. In this embodiment, an analog signal and a digital signal are indicated by the same symbol for easy understanding. The current detection lines 10u and 10w derived from the current detectors 8u and 8w and the voltage detection lines 11u and 11w derived from the voltage detector 9 are connected to the control circuit 12. The control circuit 12 controls the PW so that the U-phase and W-phase currents and the DC output voltage have respective desired values.
An M (pulse width modulation) signal (PWM pulse) is generated. Further, the control circuit 12 does not receive the supply of the voltage detection between the DC output terminals 4 and 5, but has a means for estimating the output voltage therein. A drive circuit 13 connected to the control circuit 12 forms on / off control signals for the first to sixth switching elements Q1 to Q6 based on the PWM pulse supplied from the control circuit 12, and gates these signals. To supply. The configuration of the three-phase power converter shown in FIG. 1 is simplified by not including the DC output voltage detector, and the cost and size are reduced. Although the control circuit 12 includes an output voltage estimating unit according to the present invention, since these are integrally formed with other circuits by an IC configuration or the like,
Cost reduction and size reduction are achieved as compared with the conventional case where a DC voltage detector is provided independently.

FIG. 2 shows the control circuit 12 of FIG. 1 in detail.
The control circuit 12 includes first and second current controllers (ACR) 14 and 15 for approximating an input current waveform to a sine wave.
And a subtractor 16 for subtracting the u-phase and w-phase control signals au and aw obtained from the current controllers 14 and 15 to obtain a v-phase control signal av, and two current controllers 14 and 15 and a PWM pulse generator 17 for generating three-phase PWM pulses based on three-phase control signals au, av, aw obtained from one subtractor 16. Also,
In order to control the DC output voltage, a DC voltage command value generating circuit 18, a DC voltage estimating circuit 19, a voltage controller 20
And two multipliers 21 and 22.

The first and second current controllers 14 and 15 are connected to the current detection lines 10 u and 10 w and the first and second multipliers 2.
1, 22 and first and second multipliers 21, 22
Command value (reference value) of sine wave given by
u and 10w are compared with the current detection values Isu and Isw, and control signals (operation amounts) au and aw for causing the current detection values Isu and Isw to follow the command value are output. The first and second current controllers 14 and 15 are not shown in detail, but are well-known controllers each constituted by a comparator (subtractor) and a compensator for the above-described operation. Subtractor 16 is 2
Are connected to two current controllers 14 and 15 to form a v-phase control signal av based on the u-phase and w-phase control signals au and aw. The u-phase control signal au can be represented by au = A cos ωt, and the w-phase control signal aw can be expressed as aw = A cos ｛ω
t + (2/3) π}, and the control signal av of the v-phase can be represented by av = A cos {ωt− (2/3) π}. The control signals au, av, aw are shown in FIG.
It is a three-phase sine wave as shown in FIG. A may be a function of time. .

A PWM pulse generator 17 connected to the current controllers 14 and 15 and the subtractor 16 has a D / A converter (not shown) and a triangular wave generator for generating a triangular wave Vt shown in FIG. (Not shown), a triangular wave Vt and a control signal au,
This is a well-known circuit comprising a comparator (not shown) that compares av, aw and generates u, v, w-phase PWM pulses as shown in FIGS. 3 (B), 3 (C), 3 (D). .

FIG. 1 connected to a PWM pulse generator 17
The drive circuit 13 shown in FIG. 3B, u, v,
The w-phase PWM pulse is sent to the first, third, and fifth switching elements Q1, Q3, and Q5.
(C) The phase inversion pulse of the PWM pulse of (D) is NOT
This is a known circuit created by a circuit (not shown) and sent to the second, fourth and sixth switching elements Q2, Q4, Q6.

The first to sixth switching elements Q1 of FIG.
3B, 3C, 3D and their inverted pulses, the input currents Isu, Isv, Isw of the u, v, and w phases are obtained.
Can be approximated to a sine wave. The control of the DC output voltage Ed between the output terminals 4 and 5 is performed by the first and second multipliers 2.
This is achieved by controlling the amplitude of the current command given from the first and the second 22.

A voltage controller (AVR) 20 for controlling the output voltage Ed shown in FIG. 2 is a well-known device comprising a subtractor (not shown) for obtaining an error output and a compensator (not shown). A circuit connected to the DC voltage command value generating circuit 18 and the DC voltage estimating circuit 19, wherein an error between the command value Edr of the DC voltage command value generating circuit 18 and the estimated value Ed ′ generated from the DC voltage estimating circuit 19 is obtained. A signal is formed by a subtractor, and this error signal is sent to multipliers 21 and 22 through a compensator.

The multipliers 21 and 22 are connected to the voltage detection line 11
u, 11w, the reference sine wave corresponding to the sine wave AC of the three-phase AC power supply 1 of FIG.
2, the u-phase and w-phase reference sine waves are multiplied by a DC voltage control signal, and the amplitudes of the reference sine waves are adjusted to become current command values (reference values) of the current controllers 14 and 15.

A DC voltage estimating circuit 19 as a substitute for the DC voltage detector shown in FIG.
11w, input current detection lines 10u, 10w, and connected to the current controllers 14, 15, input AC voltages Vsu, Vsw, input currents Isu, Isw, and control signals au, aw. The estimated DC value Ed ′ is determined based on the DC voltage and sent to the voltage controller 20.

The DC voltage estimation circuit 19 includes a reference AC generator 23, first, second, and third coordinate conversion circuits 24,
25, 26, a subtractor 27, a PI compensator 28, a multiplier 29, first, second and third coefficient units 30, 31, 3,
2 and an adder 33.

Before describing the DC voltage estimation in the DC voltage estimation circuit 19, the definition of each state quantity of the power converter of FIG. 1 will be described. Each phase voltage Vsu, V of the three-phase AC power supply 1
The instantaneous space vector V3 of sv and Vsw is defined as shown in the following equation (1). V3 = (2/3) ｛Vsu + Vsv exp (−j120 ゜) + Vsw exp (j120 ゜) (1) The voltages Vsu, Vsv, and Vsw of each phase in the equation (1) are defined as follows. Vsu = Vm cosωt Vsv = Vm cos (ωt−120 °) Vsw = Vm cos (ωt + 120 °) (2) where Vm is the maximum value of the voltage of the power supply 1 and ω is the angular frequency. Note that Vm may be a function of time.
By substituting equation (2) into equation (1), the power supply voltage vector Vs
Can be expressed by the following equation. Vs = Vmexp (jωt) (3) Similarly, the voltages Vcu, Vcv, and Vc at the AC-side input terminal (connection midpoint) of the power conversion circuit 3 in FIG.
When w is collectively represented by a vector Vc, the following equation is obtained. Vc = (Ed / 2) A expj (ωt−θ) (4) When the input currents Isu, Isv and Isw are collectively represented by a vector I, the following equation is obtained. I = Imexpj (ωt−φ) (5) The voltage vectors VL of the reactors 2u, 2v, 2w are collectively expressed by the following equation. VL = L (d / dt) Imεj ^(ωt−φ) + jωLIm (6) In the equations (4), (5) and (6), Ed is a DC voltage, and Im is a maximum value A of an input current is a modulation factor. Indicates the size of Ailm may be a function of time. Vs and Vc
And VL have the following relationship: Vs = Vc + The VL (7), equation (3) to (7) In its contact on a rotating coordinate theta ^{j? T} of the power supply voltage vector Vs both sides of (i.e. formula (17) theta
⁽ divide by ^jωt ) can be shown by the vector diagram of FIG.
From the above relationship, the maximum value Vm of the power supply voltage can be expressed by the following equation. Vm = (Ed / 2) Acos θ + (Ld / dt) Imcosφ + ωLImsinφ (8) The DC voltage Ed can be estimated using this equation.
Equation (8) is calculated inside the control circuit 12. Vm ′ = (Ed ′ / 2) Acos θ + (Ld / dt) Imcosφ + ωLIm sinφ (9)

The right side of the above equation can be known by detection or calculation except for Ed '. Therefore, the calculation result V of the above equation
The error between m 'and the actual value Vm is proportional to the error between Ed' and Ed. Formula to approach the actual value Vm '<br/> estimated value Vm when seeking' an estimate Ed of the DC voltage in FIG. 2 (9)
Is modified. Ed 'when Vm' = Vm
Is the estimated value of the DC voltage.

The reference AC generator 23 is connected to the u-phase voltage detection line 11u, and sinωt synchronized with the u-phase voltage Vsu
And cosωt are generated and sent to the first, second and third coordinate conversion circuits 24, 25 and 26. The coordinate conversion circuit converts the input amount into a two-axis orthogonal coordinate vector, and the vector e
Perform the operation of dividing by ^{j ωt} .

The first coordinate conversion circuit 24 is a circuit for executing a calculation for obtaining the maximum value Vm of the amplitude of the input AC voltage, and is connected to the AC voltage detection lines 11 u and 11 w and the reference AC generator 23. ing. In the first coordinate conversion circuit 24, Vm is obtained from the following equation (10). Vs α = Vm cosωt cosωt - { Vm / (3 1/2)} {cosωt + 2 cosωt + 2π / 3} sinωt = Vm (10) Equation (10) converts the three-phase coordinates to orthogonal coordinates of the two-axis, further power supply voltage Can be obtained by converting to the rotational coordinates e ^{j ωt} of The following equation (11) shows a coordinate conversion operation for deriving Vs α.

[0022]

(Equation 1)

It should be noted that Vsu, V in the above equation (11)
sw has the following values: Note that Vm may be a time function. Vsu = Vmcosωt Vsw = Vmcos (ωt + 2π / 3)

The second coordinate conversion circuit 25 calculates the first coordinate of the equation (9).
The term A cos θ of the term
4 and 15 and the reference AC generator 23.
The second coordinate conversion circuit 25 controls the u- and w-phase current control a
aα = A cos θ is obtained based on u, aw and sinωt, cosωt of the reference alternating current. The following equation (12) shows a coordinate conversion operation for obtaining aα.

[0025]

(Equation 2)

Note that au, a in the above equation (12)
w has the following values: au = Acos (ωt + θ) aw = Acos {ωt + (2π / 3) + θ} Accordingly, the calculation result of aα = Aconθ is obtained.

From the PI compensator 28, the estimated DC voltage E
Since d 'is obtained, Ed' / 2 is obtained from the coefficient unit 32 connected thereto. In the multiplier 29 connected to the second coordinate conversion circuit 25 and the coefficient unit 32, A conθ and Ed ′
/ 2 is multiplied by (Ed '/ 2) of the first term of the equation (9).
A value indicating A conθ is obtained.

The third coordinate conversion circuit 26 is connected to the current detection lines 10u and 10w and the reference AC generator 23,
Is α = Im cosφ Is β = Im sin φ is obtained based on Isu, Isw, sinωt, and cosωt. The calculation for obtaining Is α and Is β is executed by the following equation (13).

[0029]

(Equation 3)

It should be noted that Isu and Isu in the calculation of equation (13)
sw has the following formula: Isu = Imcos (ωt + φ) Isw = Imcos {ωt + (2π / 3) + φ}

The coefficient unit 30 connected to the third coordinate conversion circuit 26 calculates the coefficient Ld / dt of the second term of the equation (8) as Is α
And outputs (Ld / dt) Im cos φ. Here, Ld / dt is indicated by Ls.

The coefficient unit 31 connected to the third coordinate conversion circuit 26 multiplies Is β by the coefficient ωL of the third term of the equation (8) and outputs ωLIm sinφ.

The adder 33 is connected to the multiplier 29 and the two coefficient units 30 and 31, and outputs the outputs (Ed '/ Ed').
2) A cos θ, LsIm cos φ, and ωLIm sin φ are added to obtain a value Vm ′ corresponding to the equation (9), and this is sent to the subtracter 27.

The subtracter 27 is connected to the first coordinate conversion circuit 24 and the adder 33, and outputs a signal corresponding to the difference between the two. That is, a signal representing the difference between the detected maximum AC power supply voltage Vm obtained from the first coordinate conversion circuit 24 and the estimated maximum AC power supply voltage Vm ′ obtained from the adder 33 is output.

The PI compensator 28 connected to the subtractor 27 functions as an adapting mechanism, and a signal Ed 'for reducing the difference between the maximum value Vm of the detected voltage and the maximum value Vm' of the estimated voltage to zero.
Is sent. Since the signal Ed 'for making this difference zero includes the fluctuation information of the DC voltage between the DC output terminals 4 and 5 in FIG.
0 can be used. It should be noted that components other than the PWM pulse generator 17 in FIG. 2 are constituted by digital circuits, and the PWM pulse generator 17 and the reference AC generator 2 in FIG.
Other than 3 is constituted by a DSP (digital signal processor).

[0036]

Second Embodiment Next, a three-phase power converter according to a second embodiment will be described with reference to FIG. However, FIG.
The same reference numerals are given to the same parts as those described above, and the description thereof will be omitted. The configuration of the main circuit of the three-phase power converter of the second embodiment is the same as that of FIG. 1 and is configured by connecting a control circuit 12a of FIG. 5 instead of the control circuit 12 of FIGS. I have.

The control circuit 12a shown in FIG. 5 is a modification of the DC voltage estimation circuit 19 of the control circuit 12 shown in FIG. The DC voltage estimating circuit 19a in FIG. 5 is different from the DC voltage estimating circuit 19 in FIG.
31 and an adder 33 are omitted. That is,
In FIG. 5, the output of the multiplier 29 is directly connected to the subtractor 27.

The circuit shown in FIG. 5 has the voltage Vs' and the current Is shown in FIG.
Is almost synchronous, that is, when the power factor is almost 1. The three-phase power converter shown in FIG. 1 is a current-following high power factor converter, and can make the input power factor substantially equal to one. Therefore, even if the DC voltage estimating circuit 19a is configured with a power factor of 1, no substantial problem occurs. When the power factor is 1, the second term (Ld / dt) Im cos φ and the third term ωLIm sin φ in the equation (8) become zero. Therefore, in FIG. 5, the signal processing circuits for the second and third terms of equation (8) are omitted. The other points are the same as those of the first embodiment, so that the same operation and effect can be obtained.

[0039]

Third Embodiment Next, a power converter according to a third embodiment will be described with reference to FIGS. However, FIGS. 6 and 7
In FIG. 7, the same reference numerals are given to the same parts as those in FIGS. 1 and 2, and the description is omitted. FIG. 6 shows a single-phase power converter, and FIG. 7 shows the control circuit of FIG. 6 in detail. The circuits of FIGS. 6 and 7 are obtained by removing one phase from the three-phase circuits of FIGS. 1 and 2, and have substantially the same operation and effect. In FIG. 6, two reactors 2u and 2v and two capacitors C1 and C2 are provided.
There can be only one.

[0040]

Fourth Embodiment Next, a control circuit according to a fourth embodiment shown in FIG. 8 will be described. However, in FIG. 8, portions common to FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. This control circuit 12a is a modification of the three-phase control circuit of FIG. 5 into a single-phase control circuit. The other points are the same as those in FIG. 5, so that the same operation and effect can be obtained.

[0041]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) In the embodiment, the input AC voltage and current are A / D converted, and various calculations and processes are executed by digital signals. However, it is possible to adopt a configuration in which this is performed by an analog circuit. (2) In the embodiment, the u phase and the w phase of the input AC voltage and current are
Although only two of the phases are detected, the v-phase can also be detected, and the control can be executed by the three-phase detection signals. Also,
In the case of a balanced power supply, C ₁ = C ₂ = C ₃ , 2u = 2v = 2w, or in the case of a single phase, the voltage and current of only one arbitrary phase can be detected, and control can be performed based on this. (3) Connect the diodes D1 to D6 to the switching element Q1.
To Q6 can be integrally formed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a three-phase power converter according to a first embodiment.

FIG. 2 is a block diagram illustrating a control circuit of FIG. 1 in detail.

FIG. 3 is a waveform chart showing a state of each unit in FIG. 1;

FIG. 4 is a vector diagram for explaining a voltage and a current of each unit in FIG. 1;

FIG. 5 is a block diagram illustrating a control circuit according to a second embodiment.

FIG. 6 is a circuit diagram showing a single-phase power converter according to a third embodiment.

FIG. 7 is a diagram showing the control circuit of FIG. 6 in detail.

FIG. 8 is a diagram illustrating a control circuit according to a fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Three-phase AC power supply 3 Power conversion circuit 12 Control circuit 19 DC voltage estimation circuit

Claims (2)

(57) [Claims] 1. A reactor (2u, 2v) connected in series to at least one of an AC power supply line (6u, 6v) for supplying a sinusoidal AC voltage, and an output terminal of the reactor (2u, 2v). , Second, third, and fourth switching elements (Q1 to Q4) connected between the first and second DC output terminals (4) and (5).
A first, second, third, and third anti-parallel connected to the first, second, third, and fourth switching elements (Q1 to Q4).
A fourth diode (D1 to D4); a smoothing capacitor (7) connected between the pair of DC output terminals (4) and (5); and a voltage (Vsu) of the AC power supply line (6u). , A current detector (8u) for detecting a current (Isu) of the AC power supply line (6u), and a desired output voltage between the DC output terminals (4) and (5). DC voltage command value generating means (18) for generating a DC voltage command value (Edr), and a voltage detector (9) and a current detector (8u). Vsu) and current (I
su) to obtain a DC voltage estimated value (Ed ′) between the DC output terminals (4) and (5), and calculates the DC voltage command value (Edr) and the DC voltage estimated value (Ed ′). A voltage control signal corresponding to the difference is created, a sine wave signal synchronized with the voltage of the AC power supply line is multiplied by the voltage control signal to create a current command signal, and a current (I
su) and a current control signal (au) corresponding to a difference between the current command signal and the first to fourth switching elements based on a current control signal (au) obtained from the control means. (Q1 to Q4)
(Pulse Width Modulation) pulse for on / off control of the first to fourth switching elements (Q
1 to Q4), comprising a PWM pulse generator (17) for controlling the power converter. 2. First, second, and third reactors (2u, 2v, 3w) connected in series to a three-phase AC power supply line (6u, 6v, 6w) for supplying a sine-wave three-phase AC voltage.
2w) and the first, second and third reactors (2u, 2v, 2
w) and first, second, third, fourth, fifth and sixth switching elements (Q1 to Q6) connected between the output terminal and the pair of DC output terminals (4) and (5). And a first, second, third, and third anti-parallel connected to the first, second, third, fourth, fifth, and sixth switching elements (Q1 to Q6). Fourth, fifth and sixth diodes (D1 to D
6), a smoothing capacitor (7) connected between the pair of DC output terminals (4) and (5), and voltages (Vsu, Vsv, and Vsv) of the three-phase AC power supply lines (6u, 6v, and 6w). Vsw), and a voltage detector (9) for detecting at least one of the currents (Isu, Isv, Isw) of the three-phase AC power supply lines (6u, 6v, 6w). A current detector (8u, 8w); DC voltage command value generating means (18) for generating a DC voltage command value (Edr) indicating a desired output voltage between the DC output terminals (4) and (5); Voltage detector (9) and said current detector (8u, 8w)
And the voltage of the AC power supply line (Vsu, Vs
w) and the currents (Isu, Isw) to obtain an estimated DC voltage value (Ed ') between the DC output terminals (4) and (5), and to obtain the DC voltage command value (Edr) and the DC voltage estimation value. A voltage command signal corresponding to the difference between the AC power supply line and the sine wave signal synchronized with the voltage of the AC power supply line and the voltage control signal to generate a current command signal; Control means for generating a current control signal (au, aw) corresponding to the difference between the line current (Isu, Isw) and the current command signal; current control signals (au, aw) obtained from the control means
Based on the first to sixth switching elements (Q1 to Q1).
PWM pulse generating means (1) for generating a PWM (pulse width modulation) pulse for controlling ON / OFF of Q6) and controlling the first to sixth switching elements (Q1 to Q6).
7) A power conversion device comprising: