JP2020129936A - Ac power conversion device - Google Patents

Abstract

To attain downsizing/cost reduction and efficiency improvement with regard to an AC power conversion device which converts a single-phase alternating current into a three-phase alternating current.SOLUTION: A control unit 60 of PWM control comprises a phase detection section 61, a voltage control calculation section 62, a current control calculation section 63 and a switching control signal generation section 64. The phase detection section calculates a phase θof an inter-line voltage between first and second single-phase-side bus bars and a phase θof a voltage of a third three-phase-side bus bar. The voltage control calculation section calculates a command vector Vto the voltage of the third three-phase-side bus bar from a voltage peak command value Vto the third three-phase-side bus bar. The current control calculation section calculates a command vector Vto an inter-line voltage Vbetween first and second three-phase-side bus bars from a single-phase current command vector I. The switching control signal generation section generates a switching control signal in such a manner that output voltage vectors V, Vand Vof the three three-phase-side bus bars have predetermined magnitudes and phases.SELECTED DRAWING: Figure 1

Description

The present invention relates to an AC power conversion device that converts single-phase AC into three-phase AC.

It is easy to extract single-phase alternating current from three-phase alternating current. On the other hand, conversely, in order to generate three-phase alternating current from single-phase alternating current, generally, the first converter (converter) once rectifies the single-phase alternating current into direct current, and then the direct current is converted into the second converter. A method of converting into three-phase alternating current with an (inverter) is used (for example, refer to Patent Document 1).

JP, 2012-213298, A

However, in order to generate three-phase alternating current from single-phase alternating current, many devices must be interposed.

For example, the AC power converter described in Patent Document 1 requires a Scott transformer, a converter, and an inverter. That is, as shown in FIG. 8, a first single-phase AC terminal electrically connected to the single-phase power supply 1 and a second single-phase AC terminal connected to an inverter 13 described later are output as three-phase AC. A single-phase power source 1 having a three-phase alternating current terminal and a single-phase power source 1 electrically connected in parallel with the first single-phase alternating-current terminal of the Scott transformer 11. A converter 12 for converting alternating current into direct current power, and an inverter 13 for converting direct current power from the converter 12 into single phase alternating current supplied to the second single phase alternating current terminal of the Scott transformer 11 are configured. ing.

However, such a configuration not only becomes large in size and cost, but also has a problem that the conversion efficiency is deteriorated.

The present invention has been made in view of the above circumstances, and relates to an AC power conversion device that converts a single-phase AC into a three-phase AC, without using a transformer, and simply using one three-phase inverter. The purpose is to enable highly efficient conversion of single-phase alternating current into three-phase alternating current in the configuration.

The present invention solves the above problems by taking the following means.

The AC power converter according to the present invention is
A three-phase inverter is arranged between the input-side single-phase AC system and the output-side three-phase AC system,
The three-phase inverter is configured by connecting first to third switching arms and a DC side capacitor in parallel,
Two of the three three-phase side busbars of the three-phase AC system are respectively directly connected to the first and second two single-phase side busbars of the single-phase AC system. It is configured on the second three-phase side busbar,
The remaining one of the three three-phase side busbars is a non-directly connected third three-phase side busbar that is not directly connected to the two single-phase side busbars,
The first single-phase side busbar and the first three-phase side busbar directly connected are connected to the AC input/output terminals of the first switching arm,
The second single-phase side busbar and the directly connected second three-phase side busbar are connected to AC input/output terminals of the second switching arm,
The non-directly connected third three-phase side bus bar is connected to an AC input/output terminal of the third switching arm,
The control unit for switching control of the first to third switching arms performs current control on the first and second switching arms and voltage control on the third switching arm. Characterize.

The AC power converter of the present invention having the above-described configuration has the following several preferable modes. For easy understanding, the numerical relationship will be described together with the reference numerals used in the embodiments described later. It should be noted that the present invention should not be limitedly interpreted with reference to the reference signs.

(1) The control unit includes a phase detection unit, a voltage control calculation unit, a current control calculation unit, and a switching control signal generation unit,
The phase detection unit has a function of detecting a phase (θ ₁₂ ) of a line voltage (V ₁₂ ) between the first single-phase side bus bar and the second single-phase side bus bar, and the voltage control The arithmetic unit has a function of obtaining a command vector (V _α ) for the voltage of the non-directly connected third three-phase side busbar,
The current control calculation unit has a function of _obtaining a command vector (V _β ) with respect to a line voltage (V ₁₂ ) between the first and second three-phase side buses directly connected to each other,
The switching control signal generation unit generates a command vector (V _α ) for the voltage of the third three-phase side bus and a command vector (V _β ) for the line voltage between the first and second three-phase side buses. Based on the above, so that the output voltage vectors (V _invV , V _invW , V _invU ) of each of the first, second and third three-phase side busbars have a predetermined magnitude and phase, There is a mode that it has a function of generating and outputting a switching control signal for the third switching arm.

(2) Further, the phase detection unit detects the phase (θ ₁₂ ) of the line voltage (V ₁₂ ) between the first single-phase side bus bar and the second single-phase side bus bar, and has a function of determining the phase (theta ₃₎ of the third three-phase side bus voltage of the off-line by calculating the phase (theta ₁₂₎ of the line voltage _{(V 12) (V 3)} ,
The voltage control calculation unit performs feedback control that minimizes a deviation between a detected voltage value (V ₃ ) of the third non-directly connected three-phase side bus and a predetermined target voltage value infinitely. voltage peak command value for three phases side bus of _(V 3ref) look, this voltage peak command value _(V 3ref) and said third three-phase side bus voltage of the non-directly connected (V ₃₎ phase (theta ₃₎ To a command vector (V _α ) for the voltage of the non-directly connected third three-phase side busbar,
The current control calculation unit obtains a single-phase current peak command value (I _ref ) for the first single-phase side bus bar by feedback control that stabilizes the voltage (E) across the DC side capacitor to a predetermined value. A single-phase current command vector (I _Kref ) is obtained from the single-phase current peak command value (I _ref ) and the phase (θ ₁₂ ) of the line voltage (V ₁₂ ) to obtain the first or second single-phase side bus bar. Feedback control is performed to minimize the deviation between the single-phase current detection vector (I _K ) and the single-phase current command vector (I _Kref ) _infinitely, and the direct connection between the first and second three-phase side busbars is performed. There is a mode that it has a function of _obtaining a command vector (V _β ) for the line voltage (V ₁₂ ).

According to the above configuration of the present invention, an AC power conversion device for converting a single-phase alternating current into a three-phase alternating current has a simple configuration without using a transformer and using only one three-phase inverter. Can be converted into three-phase alternating current with high efficiency.

According to the present invention, it is possible to reduce the size, cost, and efficiency of an AC power conversion device that converts single-phase AC into three-phase AC.

Circuit diagram showing a configuration of an AC power converter in an embodiment of the present invention A circuit diagram showing an internal configuration of a filter such as LC of an AC power converter according to an embodiment of the present invention. FIG. 3 is a block diagram showing an internal configuration of a voltage control calculation unit of the AC power converter according to the embodiment of the present invention. FIG. 3 is a block diagram showing an internal configuration of a current control arithmetic unit of the AC power converter according to the embodiment of the present invention. FIG. 3 is a block diagram showing an internal configuration of a switching control signal generation unit of the AC power converter according to the embodiment of the present invention. Vector diagram for explaining the operation of the AC power converter in the embodiment of the present invention Waveform diagram for explaining the operation of the AC power converter in the embodiment of the present invention Circuit diagram showing the configuration of a conventional AC power converter

Hereinafter, the AC power conversion device of the present invention having the above-described configuration will be described in detail at the level of a specific example.

FIG. 1 is a circuit diagram showing the configuration of an AC power converter according to an embodiment of the present invention. In FIG. 1, 30 is an input-side single-phase AC system, 40 is an output-side three-phase AC system, 50 is a three-phase inverter, and 60 is a control unit for PWM control. Reference numeral 31 is a first single-phase side bus bar in the single-phase AC system 30, 32 is a second single-phase side bus bar, 41 is a first directly connected three-phase side bus bar in the three-phase AC system 40, and 42 is a second directly connected line. Is a three-phase side busbar, and 43 is a non-directly connected third three-phase side busbar. Here, "direct connection" means being directly connected to the first single-phase side bus 31 or the second single-phase side bus 32 in the single-phase AC system 30, and "non-direct connection" Means that there is no such direct connection.

Reference numeral 51 is a first switching arm of the three-phase inverter 50, 52 is a second switching arm, 53 is a third switching arm, and 54 is a DC side capacitor. Reference numeral 61 is a phase detection unit in the control unit 60, 62 is a voltage control calculation unit, 63 is a current control calculation unit, and 64 is a switching control signal generation unit.

The three-phase inverter 50 connected between the input-side single-phase AC system 30 and the output-side three-phase AC system 40 has the first to third switching arms 51, 52, 53 and the DC-side capacitor 54. It is configured by being connected in parallel. This is no different from a typical three-phase inverter.

The three-phase AC system 40 has three three-phase side buses 41, 42, 43, two of which are the first and second two single-phase side buses 31 of the single-phase AC system 30, respectively. , 32 are individually connected directly to the first and second three-phase side buses 41, 42 (V-phase, W-phase), and the remaining one is two single-phase side buses 31, 32. And a non-directly connected third three-phase side bus bar 43 (U-phase).

In the present embodiment, as an example of the correspondence relationship between the three phases (U-phase/V-phase/W-phase) in the three-phase alternating current and the first to third three-phase side buses 41, 42, 43, Corresponding the V phase to the first three-phase side busbar 41 of the direct connection, the W phase to the second three-phase side busbar 42 of the direct connection, and the U phase to the third three-phase side busbar 43 of the non-direct connection. I will let you.

Regarding the configuration of the three-phase inverter 50, in the first switching arm 51, the high-side switching element Q1a and the low-side switching element Q1b are connected in series via the AC input/output terminal N1, and the second switching arm 52 is high. The switching element Q2a on the side and the switching element Q2b on the low side are connected in series via an AC input/output terminal N2, and the third switching arm 53 connects the switching element Q3a on the high side and the switching element Q3b on the low side to AC input/output. The first to third switching arms 51, 52, 53 are connected in parallel with each other in series via the terminal N3, and in addition, the DC side capacitor 54 is also connected in parallel.

Regarding the relationship between the single-phase AC system 30 and the three-phase inverter 50, the first single-phase side bus bar 31 is connected to the AC input/output terminal N1 of the first switching arm 51, and the second single-phase side bus bar 32 is the second. The switching arm 52 is connected to the AC input/output terminal N2.

Regarding the relationship between the three-phase AC system 40 and the three-phase inverter 50, the first three-phase side bus bar 41 (V phase) directly connected to the first single-phase side bus bar 31 is the AC input/output terminal N1 of the first switching arm 51. And the second three-phase side bus bar 42 (W phase) directly connected to the second single-phase side bus bar 32 is connected to the AC input/output terminal N2 of the second switching arm 52, and the first single-phase side bus The third three-phase side bus 43 (U phase), which has a non-direct connection relationship with both the bus 31 and the second single-phase side bus 32, is connected to the AC input/output terminal N3 of the third switching arm 53. It is connected.

A filter 44 such as an LC is connected between the first to third three-phase side buses 41 (V phase), 42 (W phase), 43 (U phase) in the immediate vicinity of the AC input/output terminals N1, N2, N3. Has been done. The filter 44 is for shaping the voltage waveform of the three-phase AC generated by the switching operation of the three-phase inverter 50 into a highly accurate sine wave.

An example of a detailed circuit configuration of the filter 44 is shown in FIG. The coils L _1a and L _1b are inserted into the first three-phase side bus bar 41, the coils L _2a and L _2b are inserted into the second three-phase side bus line 42, and the third three-phase side bus line 43 is inserted. The coils L _3a and L _3b are inserted. A capacitor C ₁₂ is connected between the first and second three-phase side buses 41 and 42, and a capacitor C ₂₃ is connected between the second and third three-phase side buses 42 and 43. A capacitor C ₃₁ is connected between the first three-phase side buses 43, 41.

As described above, in order to convert the power of the single-phase alternating current into the three-phase alternating current, a method is used in which only one three-phase inverter 50 is used as a converter and a transformer is not used, but such a method is realized. The control unit 60 of the PWM control for the first to third switching arms 51, 52, 53 in the three-phase inverter 50 for doing so is configured as follows.

That is, the control unit 60 includes the phase detection unit 61, the voltage control calculation unit 62, the current control calculation unit 63, and the switching control signal generation unit 64, and these respective constituent elements are configured as follows. ing.

The phase detection unit 61 uses the first single-phase side bus bar 31 and the second single-phase side as the detection phase processed by the phase comparator (PFD) in the preceding stage in the PLL (Phase Locked Loop) circuit. non together, by calculating from the line voltage V ₁₂ phase θ ₁₂ (θ _VW) of (V _VW) for detecting the line voltage V ₁₂ phase θ ₁₂ (θ _VW) of (V _VW) between the bus 32 It has a function of obtaining the phase θ ₃ (θ _U ) of the voltage V ₃ (V _U ) of the third three-phase side bus 43 (U phase) directly connected.

The phase detector 61 is, for example,
θ ₃ =θ ₁₂ +90° That is, θ _U =θ _VW +90°
The line voltage V ₁₂ (V between the V phase and the W phase) between the directly connected first three-phase side bus 41 (V phase) and the directly connected second three-phase side bus 42 (W phase) _It has a function of obtaining the phase θ ₃ (θ _U ) of the voltage V ₃ (V _U ) of the non-directly connected third three-phase side bus 43 (U phase) from the phase θ ₁₂ (θ _VW ) of _VW ). .. The phase θ ₁₂ (θ _VW ) is sent to the current control calculation unit 63, and the phase θ ₃ (θ _U ) is sent to the voltage control calculation unit 62.

In the above phase calculation, the clockwise direction is the positive direction of the phase in this embodiment.

The voltage control calculation unit 62 is not directly connected to the feedback control unit 62a that maintains the detected voltage value V ₃ (V _U ) at a predetermined magnitude for the third non-directly connected third three-phase side bus 43 (U phase). and a command vector calculating unit 62b for obtaining the command vector V _alpha (a first command vector V _alpha) with respect to the voltage V ₃ of the third three-phase side bus 43 (U-phase) (V _U) ..

As shown in detail in FIG. 3, the feedback control unit 62a as the above-described component performs an effective value calculation on the detected voltage value V ₃ (V _U ) of the non-directly connected third three-phase side bus 43 (U phase). , And a deviation between this and a predetermined target voltage value, feedback control is performed so that the deviation is minimized infinitely, and the information obtained as a result is non-directly connected to the third three-phase side bus 43 (U phase). ) _Is sent to the command vector calculation unit 62b in the _subsequent stage as a voltage peak command value V _3ref (V _Uref ).

The command vector calculation unit 62b as the component receives the phase θ ₃ (θ _U ) of the voltage V ₃ (V _U ) of the non-directly connected third three-phase side bus 43 (U phase) from the phase detection unit 61. , A cosine function operation (cos operation) is applied to this to generate a cosine function cos θ ₃ (cos θ _U ), and a voltage peak command value V _3ref (V _Uref ) is received from the feedback control unit 62a at the _previous stage. This is multiplied by the cosine function cos θ ₃ (cos θ _U ) to obtain a command vector V _α (first command) for the voltage V ₃ (V _U ) of the non-directly connected third three-phase side bus 43 (U phase). Vector) that is,
V _α =V _3ref · _{cosθ 3} That is, V _α =V _Uref · _{cosθ U}
Is configured to have the function of seeking. The first command vector V _α is sent to the switching control signal generator 64.

The current control calculation unit 63 includes a preceding feedback control unit 63a for _obtaining the single-phase current peak command value I _ref of the first single-phase side bus 31 and a single-phase current for _{obtaining the} single-phase current command vector I _Kref. A command vector for the line voltage V ₁₂ (V _VW ) between the command vector calculation unit 63b and the first three-phase side bus 41 (V phase) and the second three-phase side bus 42 (W phase) that are directly connected A feedback control unit 63c in a subsequent stage for obtaining V _β (referred to as a second command vector V _β ) is provided.

As shown in detail in FIG. 4, the feedback control section 63a in the preceding stage as the above-mentioned component takes the deviation between the voltage E across the DC side capacitor 54 in the three-phase inverter 50 and a predetermined DC voltage command value E _ref, and Feedback control is performed so that the deviation is minimized infinitely, and the information obtained as a result is used as the single-phase current peak command value I _ref .

The single-phase current command vector calculation unit 63b as the above-mentioned constituent element includes a line voltage V ₁₂ (V _VW ) between the phase detection unit 61 and the first single-phase side bus 31 and the second single-phase side bus 32. The phase θ ₁₂ (θ _VW ) of is received, and the cosine function operation (cos operation) is applied to this to generate the cosine function cos θ ₁₂ (cos θ _VW ), and the single-phase current peak from the feedback control unit 63a in the previous stage. The command value I _ref is received, and this is multiplied by the cosine function cos θ ₁₂ (cos θ _VW ) to obtain the single-phase current command vector I _Kref ,
I _Kref =I _ref ·cos θ ₁₂ I _Kref =I _ref ·cos θ _VW
And is sent to the feedback control unit 63c in the subsequent stage.

The feedback control unit 63c at the latter stage as the above-mentioned constituent element _{divides the} single-phase current detection vector I _K on the first single-phase side bus 31 and the single-phase current command vector I _Kref received from the single-phase current command vector calculation unit 63b. The deviation is taken and feedback control is performed so that the deviation is minimized infinitely. As a result, the first three-phase side busbar 41 (V phase) and the second three-phase side busbar 42 (W phase) directly connected It has a function of _obtaining a command vector V _β (second command vector) for the line voltage V ₁₂ (V _VW ) between them. The second command vector V _β is
V _β =V ₁₂ ·cos θ ₁₂ That is, V _β =V _VW ·cos θ _VW
Becomes The second command vector V _β is sent to the switching control signal generation unit 64.

As a result of the calculation in the current control calculation unit 63, the line voltage between the first single-phase side bus 31 and the second single-phase side bus 32, which is the basis of the phase θ ₁₂ (θ _VW ). With respect to V ₁₂ (V _VW ), the single-phase current detection vector I _K in the first single-phase side bus 31 (or the same in the second single-phase side bus 32) is in phase, and the power factor is adjusted to 1. It will be. When the power factor is adjusted to 1, the phase of the line voltage vector between the single-phase side busbars and the phase of the single-phase current vector are maintained in the same phase, and the ratio of the magnitudes of these two vectors changes to the phase. Regardless, it is always kept constant.

Therefore, the relative relationship between the phase of the second command vector V _{β and} the phase of the first command vector V _α is that the voltage V ₃ (V _U of the non-directly connected third three-phase side bus 43 (U phase) ) Phase θ ₃ (θ _U ), the phase θ ₁₂ (θ _VW ) of the line voltage V ₁₂ (V _VW ) directly connected between the first and second three-phase side buses 41 and 42 (between V phase and W phase). Is equivalent to the relative relationship of.

The switching control signal generation unit 64, based on the first command vector V _α and the second command vector V _β obtained above, the first, second and third three-phase side buses 41, 42. , 43 has a function of generating and outputting switching control signals to the first to third switching arms 51, 52, 53 so that the output voltage vectors of the respective output voltage vectors have a predetermined magnitude and phase.

That is, the output voltage vector V _invU from the AC input/output terminal N3 of the third switching arm 53 (U phase) in the three-phase inverter 50 is controlled so as to match the command vector V _α, and at the same time, the first switching arm is controlled. 51 the output voltage vector V from the AC input terminal N1 of the (V-phase) _InvV and second switching arm 52 (W phase), respectively first the output voltage vector V _invW from the AC output terminal N2 of the command vector V Control is performed from _α and the second command vector V _β according to the following calculation (FIG. 5).

V _invU =V _α
V _invV =-(1/2)V _α +(√3/2)V _β
V _invW =-(1/2)V _α- (√3/2)V _β
The switching control signal generation unit 64 controls the high-side and low-side switching elements Q1a, Q1b, Q2a, in the first to third switching arms 51, 52, 53 so that these three vector operations are simultaneously established. It has a function of generating and outputting a PWM control signal for Q2b, Q3a, and Q3b. In the above formula, the notation “√3” means “square root of 3” (square root 3).

The first command vector V _α is
V _α =V _3ref · _{cosθ 3} That is, V _α =V _Uref · _{cosθ U}
Has become. The second command vector V _β is
V _β =V ₁₂ ·cos θ ₁₂ That is, V _β =V _VW ·cos θ _VW
Has become. The relationship between the phase θ ₃ (θ _U ) and the phase θ ₁₂ (θ _VW ) is as described above.
θ ₃ =θ ₁₂ +90° That is, θ _U =θ _VW +90°
Has become.

FIG. 6A shows a relative relationship between the first command vector V _α and the second command vector V _β using a vector diagram (complex number display). The horizontal axis is the real axis and the vertical axis is the imaginary axis. The phase θ _β of the second command vector V _β is deviated in the negative direction (counterclockwise direction) from the phase θ _α of the first command vector V _α . The shifted phase is 90°.

When the normalization of the first command vector V _{α along the} real axis is performed, the result is as shown in FIG. 6B, and the second command vector V _β is in a state along the imaginary axis (upper side).

In this state, the above equation,
V _invV =-(1/2)V _α +(√3/2)V _β
V _invW =-(1/2)V _α- (√3/2)V _β
FIG. 6C shows the output voltage vector V _invV from the first switching arm 51 (V phase) and the output voltage vector V _invW from the second switching arm 52 (W phase) according to the above. The output voltage vector from the third switching arm 53 (U phase) is V _invU =V _α .

The magnitudes of the V-phase output voltage vector V _invV and the W-phase output voltage vector V _invW are the same as the magnitude of the U-phase output voltage vector V _invU . Phase theta _InvV output voltage vector V _InvV the V phase has a delay of 120 ° from the phase theta _InvU output voltage vector V _InvU of U-phase, phase theta _invW output voltage vector V _invW the W-phase is the V phase output have a delay of 120 ° from the phase theta _InvV of the voltage vector V _invV (positive clockwise phase).

The vector of the line voltage V _invVW connecting the vector tip of the W-phase output voltage vector V _{invW to} the vector tip of the V-phase output voltage vector V _invV is parallel to the second command vector V _β along the imaginary axis, and U It has a vertical relationship with the vector of the phase output voltage vector V _invU . The magnitude of the vector of the line voltage V _invVW is √3 times the second command vector V _β .

The waveform of FIG. 7 shows the simulation result of the experiment of the system of this embodiment. Waveform #1 is a sine wave waveform of a single-phase voltage (V _VW ), waveform #2 is a sine wave waveform of a single-phase current (I _K ), waveform #3 is a sine wave waveform of a U-phase output voltage (V _invU ), The waveform #4 is a sine wave waveform of the V-phase output voltage (V _invV ), and the waveform #5 is a sine wave waveform of the W-phase output voltage (V _invW ).

The sine wave waveform #1 of the single-phase voltage (V _VW ) and the sine wave waveform #2 of the single-phase current (I _K ) are in phase with a power factor of 1. The sine wave waveform #3 of the U-phase output voltage (V _invU ), the sine wave waveform #4 of the V-phase output voltage (V _invV ) and the sine wave waveform #5 of the W-phase output voltage (V _invW ) have mutually amplitudes. Are equal and there is a phase difference of 120°.

As described above, according to the present embodiment, it is possible to convert a single-phase alternating current into a three-phase alternating current with high efficiency with a simple configuration in which the required number of three-phase inverters is only one and a transformer is not used. It is possible to realize downsizing, cost reduction and high efficiency of the AC power converter.

INDUSTRIAL APPLICABILITY The present invention is useful as a technique for reducing the size, reducing the cost, and improving the efficiency of an AC power conversion device that converts single-phase AC into three-phase AC.

30 Single-Phase AC System 31 First Single-Phase Side Bus Bar 32 Second Single-Phase Side Bus Bar 40 Three-Phase AC System 41 Directly Connected First Three-Phase Side Bus Bar (V-Phase)
42 Directly connected second three-phase side bus bar <W phase>
43 Non-directly connected third three-phase side bus bar (U phase)
50 three-phase inverter 51 1st switching arm 52 2nd switching arm 53 3rd switching arm 54 DC side capacitor 60 control part 61 phase detection part 62 voltage control calculation part 63 current control calculation part 64 switching control signal generation part N1 , N2, N3 AC input/output terminals

Claims (3)

A three-phase inverter is arranged between the input-side single-phase AC system and the output-side three-phase AC system,
The three-phase inverter is configured by connecting first to third switching arms and a DC side capacitor in parallel,
Two of the three three-phase side busbars of the three-phase AC system are respectively directly connected to the first and second two single-phase side busbars of the single-phase AC system. It is configured on the second three-phase side busbar,
The remaining one of the three three-phase side busbars is a non-directly connected third three-phase side busbar that is not directly connected to the two single-phase side busbars,
The first single-phase side busbar and the first three-phase side busbar directly connected are connected to the AC input/output terminals of the first switching arm,
The second single-phase side busbar and the directly connected second three-phase side busbar are connected to AC input/output terminals of the second switching arm,
The non-directly connected third three-phase side bus bar is connected to an AC input/output terminal of the third switching arm,
The control unit for switching control of the first to third switching arms performs current control on the first and second switching arms and voltage control on the third switching arm. Characteristic AC power converter. The control unit includes a phase detection unit, a voltage control calculation unit, a current control calculation unit, and a switching control signal generation unit,
The phase detector has a function of detecting a phase of a line voltage between the first single-phase side bus and the second single-phase side bus.
The voltage control calculation unit has a function of obtaining a command vector for the voltage of the non-directly connected third three-phase side busbar,
The current control calculation unit has a function of obtaining a command vector for a line voltage between the first and second three-phase side buses directly connected to each other,
The switching control signal generation unit, based on the command vector for the voltage of the third three-phase side bus bar and the command vector for the line voltage between the first and second three-phase side bus bar, the first, It has a function of generating and outputting a switching control signal for the first to third switching arms so that the output voltage vectors of the second and third three-phase side buses have predetermined magnitudes and phases. The AC power converter according to claim 1. The phase detection unit calculates the phase of the voltage of the non-directly connected third three-phase side bus bar by calculating from the phase of the line voltage between the first single-phase side bus bar and the second single-phase side bus bar. Seeking
The voltage control calculation unit is configured to perform a feedback control that minimizes a deviation between a detected voltage value of the non-directly connected third three-phase side bus bar and a predetermined target voltage value to the third non-directly connected three-phase side. A function of obtaining a voltage peak command value for the bus and obtaining a command vector for the voltage of the non-directly connected third three-phase side bus from the voltage peak command value and the phase of the voltage of the non-directly connected third three-phase side bus Have
The current control calculation unit obtains a single-phase current peak command value for the first single-phase side bus bar by feedback control that stabilizes the voltage across the DC side capacitor to a predetermined value. Feedback control for obtaining a single-phase current command vector from the phase of the line voltage and minimizing the deviation between the single-phase current detection vector and the single-phase current command vector in the first or second single-phase side bus The AC power converter according to claim 2, which has a function of performing the above and obtaining a command vector for a line voltage between the first and second three-phase side busbars that are directly connected.

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