JP5078144B2 - Power conversion method and power conversion device - Google Patents

Description

  The present invention relates to a power conversion device that performs power conversion between single-phase AC power and DC power, such as an AC-DC power conversion device that converts single-phase AC power into DC power having a constant voltage.

  In power conversion between alternating current and direct current, forward conversion from alternating current to direct current is performed by a conversion device called a converter, and reverse conversion from direct current to alternating current is performed by a conversion device called an inverter.

  When such power conversion is performed in a stationary coordinate system, there is a problem that it is difficult to control AC power at high speed and with high accuracy by a control deviation. Therefore, in three-phase alternating current, it is generally performed to convert the voltage / current value on the stationary coordinate to the d-axis and q-axis on the rotating coordinate synchronized with the phase of the AC input voltage and control with the direct current value. Yes.

  Even in single-phase alternating current, it has been proposed to obtain a signal whose phase is shifted by 90 ° with respect to the alternating current value, thereby converting it into a rotating coordinate synchronized with the alternating current input voltage. In the control of active power and reactive power of this single-phase alternating current, it is expected that the control of alternating current power will be performed at high speed and with high accuracy by calculating the control target such as current and voltage on the rotation coordinate (dq coordinate). The

  For example, Patent Documents 1 and 2 are known as those that perform single-phase AC power conversion control on rotating coordinates.

  In the single-phase voltage type PWM control inverter device of Patent Document 1, the detected voltage of the output of the inverter device and the auxiliary reference obtained by delaying the detected voltage by 90 ° are input to the rotary coordinate converter, and the d-axis component of the output voltage is It is disclosed that a q-axis component is calculated and an inverter device is controlled using the calculated d-axis component and q-axis component.

  In addition, the control circuit of the semiconductor power conversion device disclosed in Patent Document 2 detects a complex vector of instantaneous values of AC voltage and AC current using Hilbert transform, and rotates current and voltage necessary for controlling active power and reactive power. It is disclosed that calculation is possible on coordinates. Further, it is disclosed that an instantaneous phase angle of a complex vector of an AC power source obtained by Hilbert transform is used as a reference signal for synchronous operation. In the circuit configuration of Patent Document 2, an imaginary axis component is calculated by Hilbert transform, a real axis component compensated for group delay by Hilbert transform is calculated by a delay circuit, and dq is calculated using the calculated imaginary axis component and real axis component. Conversion is performed and calculation is performed on the rotating coordinates.

JP-A-1-209960 (page 2, upper right column, lines 17 to 19, page 2 lower left column, line 1 to lower right column, line 5, page 3, upper left column, lines 14 and 15) JP 2003-143860 A (paragraphs 0005, 0056, 0060, 0062) Patent No. 2509890 (page 2, column 4, lines 33-40)

  In a conventional single-phase converter having a full bridge configuration, when the harmonics are included in the AC input voltage during operation, harmonics are also generated in the AC input current. Depending on the harmonic level of the AC input voltage, an excessive peak current flows in the AC input current. An excessive peak current may damage a power converter such as a converter. Even when a sudden fluctuation occurs in the AC input voltage, an excessive current may instantaneously flow through the input due to a delay in the control response.

  Some power conversion devices have a function to protect the device from overcurrent in order to avoid damage due to such excess current. In this overcurrent protection, the apparatus is prevented from being damaged by stopping the apparatus when an excessive current is generated.

  On the other hand, the power conversion device is applied to, for example, an uninterruptible power supply, and is connected to a device such as a computer that does not allow an instantaneous power failure. Therefore, the power conversion device is required not to stop even when harmonics are included in the AC input voltage or when the AC input voltage fluctuates rapidly.

  In an AC / DC converter, it has been proposed to add an instantaneous value of a power supply voltage to a control output while maintaining an alternating current in order to cope with a sudden change or distortion of the power supply voltage. (For example, see Patent Document 3)

  FIG. 17 is a diagram for explaining the outline of the control mode of the AC / DC converter according to Patent Document 3. In the configuration example shown in FIG. 17, the AC power supply 102 is converted into DC by the converter 103 and supplied to the load 104. In this configuration, the control circuit 114 inputs the current value Is and voltage value Vs on the AC power supply 102 side detected by the detector 121 and the voltage value Vd on the load 104 side detected by the detector 122 to input a stationary coordinate system. The current control is performed to calculate the voltage correction amount, and the converter 103 is driven by the converter control unit 118 using this voltage correction amount. At this time, the voltage value Vs of the power supply voltage is added to the voltage correction amount.

  In this configuration, the instantaneous change of the power supply voltage is directly reflected on the output of the AC / DC converter by combining the instantaneous value of the power supply voltage with the AC side voltage correction amount to obtain the output voltage of the AC / DC converter as the AC amount.

  However, what is disclosed in Patent Document 3 described above is control performed on stationary coordinates in which an instantaneous value of a power supply voltage is added to a control output while being alternating current, and cannot be applied to control performed on rotating coordinates. .

  Therefore, in the power conversion performed in the rotating coordinate system, when the AC input voltage includes harmonics or when the AC input voltage fluctuates rapidly, the first object is to suppress the fluctuation of the AC input current.

  Further, in the current control using the rotating coordinate system, it is necessary to convert the voltage command value from the rotating coordinate system to the stationary coordinate system by inverse conversion. In this inverse conversion, the phase angle of the input voltage is required as a calculation parameter. In Patent Document 1 described above, the reference phase θ is used as the phase angle, but a specific method for forming the reference phase θ is not specified.

  Further, in Patent Document 2 described above, it is shown that the calculation is performed from the imaginary axis component obtained by the Hilbert transformer and the real axis component obtained by the delay circuit. In this configuration, a delay circuit is required to compensate for the group delay included in the Hilbert transformer, and there is a problem that the configuration for calculating the phase angle of the input voltage is complicated. Further, the imaginary axis component and the real axis component also include a problem that the phase angle value of the calculated input voltage may include an error when the output signals of the Hilbert transformer and the delay circuit fluctuate. .

  Therefore, in the power conversion performed in the rotating coordinate system, the second object is to detect the phase angle of the input voltage used for the conversion and the inverse conversion easily and with high accuracy.

  The purpose of suppressing the fluctuation of the first AC input current and the purpose of detecting the phase angle of the second input voltage simply and with high accuracy both solve the problems in performing power conversion in the rotating coordinate system. It solves the problem caused by the common factor of fluctuation of AC input voltage.

  In the power conversion in which the current control is performed on the single-phase power converter in the rotating coordinate system and the power conversion is performed between the single-phase AC power and the DC power, the input current value of the single-phase power converter is set to the stationary coordinate system. Is converted to a rotating coordinate system, current control is performed using the input current value converted to this rotating coordinate system, a voltage control value for controlling the single-phase converter is formed, and further, this voltage control value is added to the rotating coordinate system. The converted input voltage of the single-phase converter is added, and the single-phase converter is controlled using a voltage control value obtained by biasing the input voltage.

  According to the present invention, the current control is performed in the rotating coordinate system, and the fluctuation of the AC input current is performed by adding the input voltage of the single-phase converter converted into the rotating coordinate system to the voltage control value formed by the current control. Suppress.

  The fluctuation factor of the AC input current is due to the AC input voltage fluctuation such as harmonics included in the AC input voltage or abrupt fluctuation of the AC input voltage. The present invention suppresses the fluctuation of the AC input current by biasing the voltage fluctuation with respect to the voltage fluctuation of the AC input. The present invention can suppress fluctuations in the AC input current in the rotating coordinate system by adding the input voltage converted into the rotating coordinate system to a voltage control value obtained by controlling the current in the rotating coordinate system.

  The present invention can be applied to the form of the method and the form of the apparatus in the aspect of the converter that performs forward conversion from alternating current to direct current.

  In the form of the power conversion method of the present invention, in the power conversion method in which a single-phase converter is current-controlled in a rotating coordinate system and single-phase AC power is converted into DC power, the input current value to the single-phase converter is converted into the rotating coordinate system To convert the input current value of the rotating coordinate system into current control to form a voltage control value for controlling the single-phase converter, convert the input voltage to the single-phase converter into the rotating coordinate system, and convert the voltage control value to this voltage control value. The input voltage of the single-phase converter converted into the rotating coordinate system is biased, and the single-phase converter is controlled using the biased voltage control value.

  In the form of the power converter of the present invention, the single-phase converter that converts single-phase AC power into DC power, the rotating coordinate system control unit that performs current control in the rotating coordinate system, and the voltage value and current of the stationary coordinate system A first coordinate conversion unit that converts a value into a rotating coordinate system, a second coordinate conversion unit that converts a voltage value of the rotating coordinate system into a stationary coordinate system, and a phase of a detected value of a single-phase AC voltage and current And a phase shifter that shifts by + 90 ° or −90 °.

  FIG. 1 is a diagram for explaining a schematic configuration of a power converter according to the present invention.

  In FIG. 1, a power converter 1 converts a single-phase alternating current of a power source 2 into direct current by a converter 3 and supplies the direct current to a load 4. The converter 3 is controlled so that the voltage supplied to the load 4 becomes a predetermined voltage and the power factor becomes 1. In this converter control, a current on the input side of the converter 3 is detected, and this detected current is subjected to current control on the rotational coordinates in the rotational coordinate system control unit 13 to form a voltage control value for controlling the converter 3.

  Since the rotation coordinate system control unit 13 performs current control calculation on the rotation coordinates, the current value i and the voltage value e on the input side detected by the detector 21 are rotated from the stationary coordinate system by the first coordinate conversion unit 11. The voltage control value formed by the rotating coordinate system control unit 13 is converted from the rotating coordinate system to the stationary coordinate system by the second coordinate converting unit 12. As a result, the converter control unit 18 performs power conversion by controlling the converter 3 with the voltage control value of the stationary coordinate system.

  In order to control the converter 3, the rotating coordinate system control unit 13 includes a current control unit 14 that calculates a voltage control value and a current fluctuation suppression unit 15 that suppresses a current fluctuation due to an input voltage fluctuation. The current fluctuation suppressing unit 15 adds the input voltage e converted by the first coordinate conversion unit 11 to the voltage control value obtained by the current control unit 14. Note that the current fluctuation suppressing means 15 also has a configuration in which the current control means 14 also serves as an adder that outputs a voltage control value, and the input voltage e converted by the first coordinate conversion unit 11 is added to this adder. it can.

  In addition, since the calculation of the coordinate conversion performed by the first coordinate conversion unit 11 and the second coordinate conversion unit 12 requires a signal that is 90 ° out of phase, the phase shifter 16 detects the input side detected by the detector 21. The phases of the current value i and the voltage value e are shifted by 90 ° and sent to the current control means 14 of the rotating coordinate system control unit 13.

  Further, the phase detector 17 is connected to the phase shifter 16 and the phase angle ωt of the input voltage is obtained based on the output of the phase shifter 16. The phase angle ωt of the input voltage is used as a calculation parameter required for the coordinate conversion calculation performed by the first coordinate conversion unit 11 and the second coordinate conversion unit 12.

  In each of the above-described configurations, the current variation suppressing unit 15, the phase shifter 16, and each unit of the phase detection unit 17 using the output of the phase shifter 16 as a low-pass filter is a configuration that is characteristically provided by the present invention.

  The first coordinate conversion unit inputs a single-phase AC input current value and a current value obtained by shifting the input current value by 90 ° by the phase shifter and converts the input current value into a current value of the rotating coordinate system.

  Further, the rotating coordinate system control unit includes a current control unit and a current fluctuation suppressing unit, and any of the units can be performed by a calculation process on the rotating coordinate. The current control unit performs current control on the current value of the rotating coordinate system converted by the first coordinate conversion unit to form a voltage control value of the rotating coordinate system. The current fluctuation suppressing means adds the input voltage input to the single-phase converter to the voltage control value to suppress current fluctuation due to input voltage fluctuation.

The second coordinate conversion unit converts the voltage command value of the rotating coordinate system output from the rotating coordinate system control unit into a voltage command value of the stationary coordinate system. The single-phase converter converts AC power into DC power based on the voltage command value of the stationary coordinate system output from the second coordinate conversion unit .

The current fluctuation suppressing unit adds the voltage value of the rotating coordinate system converted by the first coordinate conversion unit to the voltage control value output by the current control unit.

  The current control means obtains the q-axis command current of the rotating coordinate system by zero, and obtains the d-axis command current of the rotating coordinate system by PI control in which the deviation between the output voltage of the single-phase converter and the voltage command value is zero. PI control is performed to set the value. By setting the q-axis command current of the rotating coordinate system to zero, the power factor can be improved and the power factor can be set to 1, and a single-phase PFC (Power Factor Correction) converter can be configured.

  The phase shifter of the present invention is a device that shifts the phase of a detected value of a single-phase AC voltage and current by + 90 ° or −90 °, and can be configured by a 90 ° advance circuit using an operational amplifier, for example. The 90 ° advance circuit using the operational amplifier provided in the present invention can be configured such that the feedback resistance of the operational amplifier is a parallel circuit of a first capacitor and a series resistor whose connection point is grounded via the second capacitor. . The frequency characteristic of the 90 ° advance circuit can be determined by adjusting the resistor and the capacitor. The frequency characteristic of the phase shifter is a characteristic having a predetermined gain at a predetermined frequency and a phase shift of 90 °. By setting the predetermined frequency as an AC frequency converted by the power conversion device, only the phase can be advanced by 90 ° without changing the magnitude in the frequency at which the power conversion is performed.

  The power conversion device of the present invention is not limited to a 90 ° advance circuit as a phase shifter, and may be configured using a 90 ° delay circuit. The 90 ° delay circuit can be configured, for example, by connecting a phase inversion circuit to the 90 ° advance circuit described above.

  The power conversion device of the present invention includes a first coordinate conversion unit that converts a voltage value and a current value of a stationary coordinate system into a rotation coordinate system in order to perform current control by calculation on the rotation coordinate. To control the single-phase converter using the voltage control value obtained by the current control on the rotating coordinate, the voltage control value on the rotating coordinate is set to the stationary coordinate in accordance with the single-phase converter driven on the stationary coordinate. It is necessary to convert back to the voltage control value above. The power conversion device of the present invention includes a second coordinate conversion unit for performing inverse conversion from the rotating coordinate system to the stationary coordinate system.

  The first coordinate conversion unit and the second coordinate conversion unit require the phase angle of the input voltage as a calculation parameter in order to perform the coordinate conversion calculation. The power converter of the present invention includes phase detection means for detecting the phase angle of the input voltage. This phase detection means uses the output of the phase shifter, and detects the phase angle of the input voltage with reference to the zero point of the low-pass filter output by the phase shifter.

  The phase shifter configured by a 90 ° advance circuit using the operational amplifier of the present invention has a low-pass filter characteristic in addition to the characteristic of advancing the phase of the input voltage by 90 °. Therefore, even when the input voltage signal includes a high frequency component and a peak component, the high frequency component and the peak component are removed by the characteristics of the low-pass filter, and the fundamental wave can be extracted.

  Further, by setting the gain with respect to the direct current component of the 90 ° advance circuit using the operational amplifier of the present invention to a finite value, saturation due to amplification of the offset voltage included in the input signal can be prevented.

  When detecting the phase angle based on the zero point at which the output of the phase shifter becomes zero, the phase detection means can prevent the zero point from being erroneously detected by removing the high frequency component and the peak component from the signal component. The phase angle can be detected with high accuracy.

  Further, according to the configuration of the present invention, the phase shifter provided for converting the input voltage value to the rotating coordinate system can be used for phase detection, so that the circuit configuration can be simplified and miniaturized.

  The single-phase converter included in the present invention may be configured by a single-phase bridge circuit in which a switch element in which a self-extinguishing element and a diode are connected in parallel is bridge-connected between an input terminal and an output terminal, for example. it can. AC power is converted to DC power by opening and closing each switch element according to a voltage command value.

  According to the aspect of the present invention, by adding the input voltage converted to the rotation coordinate system to the voltage command value on the rotation coordinate, it is possible to suppress the fluctuation of the AC input current due to the fluctuation of the AC input voltage. .

  According to the aspect of the present invention, by providing the phase shifter with the characteristics of a low-pass filter, it is possible to easily and accurately detect the calculation parameter of the phase angle used for coordinate conversion.

  According to the aspect of the present invention, the offset voltage included in the input voltage is amplified by using a 90 ° advance circuit using an operational amplifier as a phase shifter and setting the gain of the DC signal of this 90 ° advance circuit to a finite value. To prevent saturation.

  As described above, according to the power conversion device of the present invention, it is possible to solve the problem caused by the fluctuation of the AC input voltage.

  More specifically, according to the power conversion device of the present invention, in the power conversion performed in the rotating coordinate system, when the AC input voltage includes harmonics or when the AC input voltage fluctuates rapidly, the AC input current Variations can be suppressed.

  Further, in the power conversion performed in the rotating coordinate system, the phase angle of the input voltage used for the coordinate conversion of conversion and inverse conversion can be detected easily and with high accuracy.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a diagram for explaining a configuration example of the power conversion device of the present invention. FIG. 2 is a diagram showing in detail the schematic configuration shown in FIG.

  In FIG. 2, the power source 2 is an AC power source 2A, and the converter 3 is constituted by a single-phase bridge circuit formed by bridge-connecting switch elements 3a to 3d in which a self-extinguishing element and a diode are connected in parallel. An AC power source 2A is connected via an inductance L, and an output terminal is connected to a load 4 via a smoothing capacitor.

  The switching elements 3a to 3d are controlled in opening / closing timing and opening / closing interval by a control pulse signal from the control pulse generator 18b, and the AC power from the AC power source 2A is converted into DC power and supplied to the load 4.

  The current detection means 21A detects the input current value on the AC power supply 2A side, and the voltage detection means 21B detects the input voltage value on the AC power supply 2A side. The current detection unit 21A inputs the detected current value to the rotation coordinate conversion unit 11A constituting the first coordinate conversion unit 11 and also to the 90 ° advance circuit 16A constituting the phase shifter 16. In addition, the voltage detection unit 21B inputs the detected voltage value to the rotation coordinate conversion unit 11B constituting the first coordinate conversion unit 11 and to the 90 ° advance circuit 16B constituting the phase shifter 16.

  The 90 ° advance circuit 16A and the 90 ° advance circuit 16B can be configured by operational amplifiers, have a predetermined gain at a predetermined frequency, and have a frequency characteristic having a phase shift of 90 °. Details of the 90 ° advance circuit will be described later.

The rotating coordinate conversion unit 11A receives the AC input current i _a ′ of the stationary coordinate system from the current detection unit 21A, and receives the AC input current i _b ′ of the stationary coordinate system from the 90 ° advance circuit 16A. The AC input current i _b ′ is a signal whose phase is advanced by 90 ° with respect to the AC input current i _a ′. The rotating coordinate conversion unit 11A performs a coordinate conversion operation on the input AC input current i _a ′ and AC input current i _b ′ of the stationary coordinate system, and d-axis current i of the rotating coordinate system (dq coordinate conversion system). _d ′ and q-axis current i _q ′ are calculated.

The rotating coordinate conversion unit 11B receives the AC input voltage e _a ′ of the stationary coordinate system from the voltage detection unit 21B, and receives the AC input voltage e _b ′ of the stationary coordinate system from the 90 ° advance circuit 16B. The AC input voltage e _b ′ is a signal whose phase is advanced by 90 ° with respect to the AC input voltage e _a ′. The rotating coordinate conversion means 11B performs a coordinate conversion operation on the input AC input voltage e _a ′ and AC input voltage e _b ′ of the stationary coordinate system, and d-axis voltage e of the rotating coordinate system (dq coordinate conversion system). _d ′ and q-axis voltage e _q ′ are calculated.

Further, the phase detector 17 receives the AC input voltage e _b ′ of the stationary coordinate system from the 90 ° advance circuit 16B, and detects the time point at which the AC input voltage e _b ′ becomes zero to detect the phase angle of the input voltage. ωt is calculated. The rotation coordinate conversion means 11A and 11B perform coordinate conversion using the phase angle ωt obtained by the phase detection unit 17 as an operation parameter. The phase angle ωt is also sent to the rotating coordinate conversion unit 12 that performs inverse conversion from the rotating coordinate system to the stationary coordinate system.

The rotating coordinate system control unit 13 inputs a subtractor 31 for obtaining a deviation between the d-axis current i _d ′ and its target value i _d ^*, and (i _d ′ −i _d ^* ) obtained by the subtractor 31. , A PI controller 14a for controlling the d-axis current i _d ′ to the target value i _d ^* , a multiplier 14e for multiplying the q-axis current i _q ′ by ωL, an output of the multiplier 14e, and a PI controller 14a, a subtractor 33 for obtaining a deviation from the output 14a, a subtractor 32 for obtaining a deviation between the q-axis current i _q 'and its target value i _q ^* , and a subtracter 32 (i _q ' -i _q ^* ), the PI controller 14b for controlling the q-axis current i _q 'to the target value i _q ^* , the multiplier 14f for multiplying the d-axis current i _d ' by ωL, and the multiplier An adder 34 for adding the output of 14f and the output of the PI controller 14b is provided.

Further, the d-axis voltage e _d ′ from the rotation coordinate conversion unit 11B is added to the subtracter 33, and the q-axis voltage e _q ′ from the rotation coordinate conversion unit 11B is subtracted from the adder 34.

With this configuration, the d-axis control voltage v _d ′ is output from the subtractor 33 of the rotating coordinate system control unit 13, and the q-axis control voltage v _q ′ is output from the adder 34 of the rotating coordinate system control unit 13. .

The subtractor 33 and the adder 34 constitute current fluctuation suppressing means of the rotating coordinate system control unit 13. The current fluctuation suppression means by the subtractor 33 suppresses the current fluctuation due to the input voltage fluctuation by adding the d-axis voltage e _d ′ to the d-axis control voltage v _d ′ obtained by the current control. The current fluctuation suppression means by the adder 34 suppresses current fluctuation due to input voltage fluctuation by adding the q-axis voltage e _d ′ to the q-axis control voltage v _q ′ obtained by current control.

In the rotating coordinate system control unit 13, i _d ^* is input as a target value of the _d- axis current, and i _q ^* is input as a target value of the q-axis current.

The target value i _d ^* controls the rotating coordinate system control unit 13 so that the DC output voltage v _dc ′ of the single-phase converter 3 becomes the DC voltage command value v _dc ^* . The configuration for obtaining the target value i _d ^* includes a detector 22 that detects the DC output voltage v _dc ′ of the single-phase converter 3, designated voltage setting means 14 d that outputs a DC voltage command value v _dc ^* , and a DC output voltage. In order to hold the DC output voltage v _dc ′ constant by PI control of the subtractor 30 for obtaining the deviation between v _dc ′ and the DC voltage command value v _dc ^* and the obtained deviation (v _dc ^* −v _dc ′). And an output i _d ^* of the PI controller 14c is input as a target value to the subtractor 31 on the input side of the PI controller 14a.

On the other hand, the target value i _q ^* is a reactive current command, and the rotary coordinate system control unit 13 is controlled so that the reactive power becomes zero in the power conversion by the single-phase converter 3. The reactive current command sets the target value i _q ^* to “0” so that the reactive power is zero and the power factor is 1, and the target value i _q ^* = 0 is set as the target value on the input side of the PI controller 14b. Are input to the subtractor 32.

The coordinate conversion unit 12 inversely converts the control output of the d-axis control voltage v _d ′ and the q-axis control voltage v _q ′ obtained by the rotation coordinate system control unit 13 and reconverts from the rotation coordinate system to the stationary coordinate system. To do.

The control pulse generator 18 b generates a control pulse signal for controlling the single-phase converter 3 using the control voltage v _a ′ of the stationary coordinate system obtained by the re-conversion of the coordinate converter 12. The generation of the control pulse signal is performed, for example, by comparing the voltage value of the control voltage v _a ′ with a triangular waveform carrier signal.

  Hereinafter, in each component included in the above-described power conversion device, the configuration and operation of the 90 ° advance circuit will be described with reference to FIGS. 3 to 6, and current control performed on the rotation coordinates will be described with reference to FIGS. 7 to 10. The command value of current control will be described with reference to FIG. 11, the output of the PWM pulse will be described with reference to FIG. 12, and the embodiment of the present invention will be described with reference to FIGS.

[Configuration and operation of 90 ° lead circuit]
In the present invention, a circuit having a novel configuration using an operational amplifier is used as a circuit for forming a signal whose phase is shifted by 90 ° with respect to an AC voltage or an AC current. This 90 ° advance circuit has a frequency characteristic that outputs a signal whose phase is advanced by 90 ° at a certain frequency or higher, and at the frequency of the AC signal that is converted by the single-phase converter of the power converter, the input current signal or Advance the phase of the voltage signal by 90 °.

  In general, it is known to form a 90 ° advance circuit using an operational amplifier. FIG. 3 shows a configuration example of a 90 ° advance circuit using a general operational amplifier.

90 ° leading circuit having the circuit configuration shown in FIG. 3 is constructed by connecting the C ₁ to feedback resistor connected to R ₁ in the input resistance of the operational amplifier OP, the input signal e _a output signal e whose phase is shifted by 90 ° of Output _o .

The transfer function of this circuit is
e _o / e _a = − (1 / C ₁ R ₁ ) · (1 / s)
The gain for the direct current when the time has sufficiently passed, obtained by setting s → 0 in the above formula, is infinite. For this reason, the DC component of the offset voltage included in the input signal is integrated, and the output _eo is saturated.

Therefore, in the present invention, the 90 ° advance circuit has the circuit configuration shown in FIG. 4 to provide a predetermined frequency characteristic and solve the above-described saturation problem. The 90 ° advance circuit 40 shown in FIG. 4 has a first capacitor C ₁ as a feedback resistor connected to the operational amplifier OP and a series of resistors R _F1 and R _F2 whose connection point is grounded via the second capacitor C _2. In this configuration, a parallel circuit with a resistor is used.

In general, when an AC voltage is e _a of the formula (1), the AC input voltage e _b the phase advances 90 ° to this e _a is expressed by Equation (2).

The transfer function of the 90 ° advance circuit 40 shown in FIG. 4 is expressed by Equation (3). In equation (3), e _a is a 90 ° advance circuit input signal, and e _o is a 90 ° advance circuit output signal. Here, the input signal to the 90 ° advance circuit and the general expression of the AC voltage are both represented by ea which is _a common signal before the phase advance.

In the above formula (3), in a region where s satisfies the relationship of the following formula (4),
The transfer function (e _o / e _a ) shown in the equation (3) is expressed by the following equation (5) when an approximate equation is obtained by substituting ωt for s in the equation.

The region of s satisfying the equation (4) is a region in which the product of the frequency ω and the time t is sufficiently larger than 1 / (C ₁ (R _F1 + R _F2 + sC _F R _F1 R _F2 ), for example. The frequency ω represents a state after a sufficient time has elapsed, and the frequency ω represents a sufficiently large state when a predetermined time t has elapsed.

Here, each constant of R ₁ and C ₁ is selected so as to satisfy the following conditions.

Conditions of selection is the fundamental wave component in e _b of formula (2) (n = 1) is a region satisfying the equation (4), and those satisfying _{1 / R 1 C 1 ω 1} = 1 is there.

Note that the condition of 1 / R ₁ C ₁ ω ₁ = 1 represents a condition in which the gain is “1” in a region that satisfies Equation (4).

When the constants R ₁ and C ₁ satisfying the above conditions are selected, the amplitudes of the fundamental waves of the AC input voltages e _a and e _b can be approximated as E _b1 ≈E _a1 .

Therefore, from the relationship of this amplitude, the output signal of the 90 ° leading circuit e _o can be utilized as an output signal e _b that proceeded 90 ° phase, represented by the following equation (6).

Thus, the circuit configuration of the 90 ° leading circuit 40 shown in FIG. 4 of the present invention, an output signal e _o of the phase advanced by 90 ° of the input signal e _a.

  In the power conversion device 1 of the present invention shown in FIG. 2, the configuration example using the 90 ° advance circuit 40 as the phase shifter is shown, but the configuration example using the 90 ° delay circuit may be used. In this case, a 90 ° delay circuit having the configuration shown in FIG. 5 can be used in place of the 90 ° advance circuit shown in FIG.

The 90 ° delay circuit 42 shown in FIG. 5 can be configured by connecting a phase inverting circuit 41 to the output terminal of the 90 ° advance circuit 40 shown in FIG. The phase inversion circuit 41 can be configured, for example, by connecting an input resistor R ₂ and a feedback resistor R ₃ to the operational amplifier OP. The phase inversion circuit 41 inverts the phase of the output of the 90-degree advance circuit 40. Output signal e _b of 90 ° delay circuit 42 is expressed by the following equation (7).

  Hereinafter, the phase shifter included in the power conversion device of the present invention will be described using an example of a 90 ° advance circuit, but the same can be applied to a configuration using a 90 ° delay circuit.

An example of the 90 ° advance circuit shown in FIG. 4 used in the power conversion apparatus of the present invention will be described. Examples shown here, the fundamental wave is 50 Hz, the fundamental wave amplitude E _a1 of the input voltage e _a, substantially equal 90 ° output voltage advanced phase e _b amplitude E _b1 of the fundamental wave (E _a1 ≒ E _b1 ) The constants of C ₁ , C ₂ , R ₁ , R ₂ , R ₃ are selected.

In selecting this constant, the resistance ratio ((R _F1 + R _F2 ) / R ₁ ) between the feedback resistance (R _F1 + R _F2 ) and the input resistance R ₁ is set to about 4, for example, and the internal resistance of the operational amplifier OP is sufficiently set. Great value.

  FIG. 6 shows frequency characteristics when a 90 ° lead circuit is configured with the constants selected above, and shows simulation results calculated as a non-inverting circuit.

The 90 ° leading circuit, in the fundamental wave is 50 Hz, the amplitude of the fundamental wave of the input voltage e _a output voltage eb is set the gain to be substantially equal, the gain represents the 0dB around 50 Hz, The phase has a characteristic of maintaining −90 ° at a frequency of approximately 20 Hz or more.

According to the circuit configuration of the 90 ° advance circuit of the present invention, the gain of the DC component is (R _F1 + R _F2 ) / R _1.
Can be expressed as This gain can be obtained by setting s = 0 in equation (3).

  Therefore, since the gain of the DC component is finite, even if an offset voltage is generated in the input signal, the output signal is not saturated, as in the case of the circuit configuration of the 90 ° advance circuit shown in FIG. In addition, the problem that the output signal saturates with time does not occur.

For example, when a constant is selected as described above in the above circuit configuration, when an offset voltage of 5 mV is generated,
e _a × (R _F1 + R _F2 / R ₁ ) = 5 mV × 4 = 20 mV
Only a direct current component is output, and the problem that the output is saturated does not occur.

[Current control on rotating coordinates]
Next, converter current control performed on the rotational coordinates of the present invention will be described with reference to FIGS. FIG. 7 is a diagram for explaining the input / output relationship of the converter, FIG. 8 is a diagram for explaining the relationship between the stationary coordinate system and the rotating coordinate system, and FIG. 9 is a low-pass filter of a 90 ° phase advance circuit. FIG. 10 is a diagram for explaining the characteristics, and FIG. 10 is a diagram showing a current control block for controlling the current of the converter.

  In FIG. 7, the single-phase converter 3 includes a single-phase bridge circuit formed by bridge-connecting switch elements 3a to 3d in which a self-extinguishing element and a diode are connected in parallel between an input terminal and an output terminal. The An AC power source 2 </ b> A is connected to the input end of the single-phase converter 3 via an inductance L, and a smoothing capacitor and a load 4 are connected to the output end of the single-phase converter 3.

The switch elements 3 a to 3 d of the single-phase converter 3 are controlled to be opened and closed according to the voltage command value, convert AC power into DC power, and supply the DC power to the load 4. Note that e _a is an AC input voltage, i _a is an AC input current, and v _a is an input voltage of the converter.

In this single-phase converter, if the input voltage e _a is the real axis component of the rotation vector (indicated by the real axis (a axis) in FIG. 8), the voltage e _b whose phase is advanced by 90 ° is rotated by the 90 ° advance circuit. It can be represented by an imaginary axis component of the vector (indicated by an imaginary axis (b axis) in FIG. 8).

Further, the AC input current i _a and the input side voltage v _a are also used as the real axis components of the rotation vector, and the current i _b and the voltage v _b whose phase is advanced by 90 ° by the 90 ° advance circuit are used as the imaginary axis component of the rotation vector. Can be expressed as

The relationship between the voltages and currents of the real axis components e _a , i _a , and va and the imaginary axis components e _b , i _b , and v _b uses a matrix [C] represented by the following equation (8). Thus, it can be converted to a rotation coordinate (on the dq axis coordinate) synchronized with the input voltage. Further, the inverse matrix [C] ⁻¹ can be inversely transformed from the rotational coordinates to the stationary coordinates.

Here, the value of e _d (d-axis component) of the rotating coordinate of the AC input voltage (dq-axis coordinate), when e _q (q-axis component), the following equation by using the transformation matrix described above [C] It is represented by (9).

Similarly, the values on the rotational coordinates (dq-axis coordinates) of the AC input current are i _d (d-axis components) and i _q (q-axis components), and the rotational coordinates of the converter input voltage (dq-axis coordinates). Assuming that the upper values are v _d (d-axis component) and v _q (q-axis component), the above-described transformation matrix [C] is used to represent the following expressions (9) and (10), respectively.

  In order to perform the coordinate conversion described above, the phase angle ωt of the input voltage is necessary. In order to obtain an AC phase angle, ωt is generally determined based on the zero point of the voltage. However, when the input voltage waveform includes harmonics, zero crossing may be performed a plurality of times. As described above, when a plurality of zero crossings are performed, a zero point is detected for each zero cross, and a plurality of zero points that should be originally detected at one point are detected, and an erroneous phase is eventually detected. Become.

  On the other hand, the present invention removes harmonics included in the waveform of the input voltage by utilizing the characteristics of the low-pass filter provided in the phase shifter used to shift the phase by 90 ° for coordinate conversion, The phase angle ω is obtained from the output of the phase shifter.

  The 90 ° phase advance circuit provided in the present invention has the characteristics of a low-pass filter that attenuates harmonic components and removes noise and harmonics as shown in the frequency characteristics of FIG. In the circuit configuration, the phase shift is constant at approximately 90 ° with respect to a predetermined frequency such as 50 Hz or 60 Hz. Therefore, sinωt and cosωt are obtained with reference to the zero point for the output of the 90 ° phase advance circuit of this circuit configuration. Thus, the phase can be accurately detected.

  Further, this circuit configuration has an effect that it is not necessary to newly provide a filter circuit since a part of the circuit for coordinate conversion is diverted.

  FIG. 9 is a diagram for explaining the low-pass filter characteristics of the 90 ° phase advance circuit provided in the power converter of the present invention. According to the simulation results shown in FIGS. 9A and 9B, when an input voltage including a harmonic component is passed through a 90 ° phase advance circuit, an output voltage whose phase is shifted by 90 ° is output, and the input voltage The harmonic component contained in is removed.

  Here, in the circuit of FIG. 7, the relationship between the AC input voltage e, the AC input current i, and the input voltage v of the converter is expressed by the following equations (12) and (13).

Substituting Expressions (9), (10), and (11) into the AC input voltages e _a and e _b , the AC input currents i _a and i _b , and the converter input voltages v _a and v _b in Expression (13) above. Then, the following expression (14) is obtained in which the AC input voltage e, the AC input current i, and the input voltage v of the converter are expressed on rotation coordinates (dq axes).

From the equation (14), v _d (d axis) and v _q (q axis) representing the input voltage v of the converter in rotation coordinates (dq axis) are represented by the following equations (15) and (16).

Here, the control target value of the d-axis current i _d of the AC input current i is i _d ^* , the control target value of the q-axis current i _q of the AC input current i is i _q ^* , and the equations (15), (16 When the third term part of the right side of () is given a similar function by the PI controller, the expressions (15) and (16) are mapped to the following expressions (17) and (18) in the current control system on the rotating coordinates. can do. In the equations (17) and (18), the current control values are represented by adding “′” to each voltage (e, v) and current (i) on the main circuit of the converter.

  FIG. 10 is a current control block diagram showing the above equations (17) and (18).

Expression (17) shows generation of the input voltage v _d ′ of the inverter on the d axis in the current control of the rotating coordinate system. In Expression (17), the second term part on the right side and the third term part on the right side correspond to the current control means 14, and the first term part on the right side corresponds to the current fluctuation suppression means 15.

In the current control function, the second term part (ωLi _q ′) on the right side is generated by multiplying the q-axis current i _q ′ generated by the rotating coordinate conversion means 11A by (ωL), and the third term part on the right side. is _{(k p + k i / s} ) (i d * -i d ') was calculated by the subtracter 31 (i _d ^* -i _d' a) has a function _{(k p + k i / s} ) It is generated by passing it through a PI controller 14a, the generated (ωLi _q ') and _{(k p + k i / s} ) (i d * -i d') and is input to the subtracter 33 (ωLi _q ' ) from 'i'm subtracting), the control voltage v _d on the d-axis which performs the current _{control' (k p + k i /} s) (i d * -i d is obtained.

In the current fluctuation suppressing function, the first term portion of the right side, e _d ′, is obtained by adding the d-axis voltage e _d ′ generated by the rotating coordinate conversion means 11B to the subtractor 33 to obtain the control voltage v _d ′ as e. _This is done by biasing by _d ′.

On the other hand, Expression (18) shows generation of the input voltage v _q ′ of the inverter on the q axis in the current control of the rotating coordinate system. In Expression (18), the second term part on the right side and the third term part on the right side correspond to the current control means 14, and the first term part on the right side corresponds to the current fluctuation suppressing means 15.

In the current control function, the second term part (ωLi _d ′) on the right side is generated by multiplying the d-axis current i _d ′ generated by the rotating coordinate conversion means 11A by (ωL), and the third term part on the right side. (K _p + k _i / s) (i _q ^* −i _q ′) has a function of (k _p + k _i / s) calculated by the subtractor 32 (i _q ^* −i _q ′). The generated (ωLi _d ′) and (k _p + k _i / s) (i _q ^* −i _q ′) generated by passing through the PI controller 14 b are input to the adder 34 with the sign inverted. What i changing the sign control voltage v _q on the q axis to perform the current control 'is obtained by adding (ωLi _d') and _{(k p + k i / s} ) (i q * -i q ') Te .

The current variation suppressing function, the first term on the right side portion in which e _q 'is q-axis voltage e _q generated by the rotational coordinate conversion unit 11B' is added to the adder 34, the control voltage v _q 'to e _This is done by biasing by _q ′. As a result, control output values v _d ′, v _q ′ on the dq axis can be obtained.

[Command value for current control]
In the power conversion device of the present invention, the single-phase converter is intended to maintain a direct-current output voltage at a constant voltage and at the same time make an input current in phase with an alternating-current voltage to form a sine wave with a power factor of 1. If the q-axis current i _{q is set} to 0 on the rotating coordinates, the input current is in phase with the input voltage. By setting the q-axis current i _q command value i _q ^* = 0, the input current is in phase with the AC voltage. Can achieve the function.

On the other hand, the d-axis current i _d may be controlled to a current necessary for keeping the DC output voltage constant. Therefore, as shown in FIG. 11, the command value i _d ^* of the d-axis current i _d is a deviation (v _dc ^* −v _dc ′) between the detected value v _dc ′ of the DC output voltage and the command value v _dc ^*. Is input to the PI controller 14c, and the deviation (v _dc ^* −v _dc ′) is made zero by the PI controller 14c.

[PWM pulse output]
The d-axis control voltage v _d ′ and the q-axis control voltage v _q ′ obtained by the rotating coordinate system control unit 13 are transformed from the equation (13) using the inverse transformation matrix [C] ⁻¹ of the equation (8). Then, the AC values v _a ′ and v _b ′ on the stationary coordinates shown in FIG. 12 are restored. Of the AC values v _a ′ and v _b ′ obtained here, the b-axis is virtually provided, so that v _b ′ is not used as the control output, and only v _a ′ is used.

The control pulse generation unit 18b generates a control pulse for driving a switching element such as an IGBT of the single-phase converter 3 by comparing this v _a ′ with the triangular wave of the carrier frequency generated by the carrier triangular wave signal generation unit 18a. PWM pulse control is performed.

  Note that the generation of the control pulse signal is well known as PWM control, and a description thereof is omitted here.

[Example of Waveform of Power Converter of the Present Invention]
Examples of waveforms when power is converted by the power conversion device of the present invention will be described with reference to FIGS.

  13 and 14 show changes in the AC input current and changes in the DC output voltage when the input voltage suddenly changes, FIG. 13 shows an example of a waveform when current fluctuation suppression is not performed, and FIG. 14 shows current fluctuation suppression. The example of a waveform at the time of performing is shown.

The waveform example shown in FIG. 13 shows a case where the single-phase converter is controlled only by the control outputs v _d ′ and v _q ′ obtained by current control, and the waveform example shown in FIG. 14 shows the control output v obtained by current control. A case is shown in which a single-phase converter is controlled using a signal obtained by adding input voltages e _d ′ and e _q ′ to _d ′ and v _q ′.

  In both cases, the arrows in the figure indicate the time when the AC input voltage suddenly changes. When the input voltage suddenly changes, the AC input current and the DC output voltage shown in FIGS. 13 and 14 are compared, and it is confirmed that the fluctuation range is reduced when the current fluctuation is suppressed.

  15 and 16 show changes in the AC input current with respect to distortion of the input voltage, FIG. 15 shows an example of a waveform when current fluctuation suppression is not performed, and FIG. 16 shows a waveform when current fluctuation suppression is performed. An example is shown.

The waveform example shown in FIG. 15 shows a case where the single-phase converter is controlled only by the control outputs v _d ′ and v _q ′ obtained by current control, and the waveform example shown in FIG. 16 shows the control output v obtained by current control. A case is shown in which a single-phase converter is controlled using a signal obtained by adding input voltages e _d ′ and e _q ′ to _d ′ and v _q ′.

  Assuming that the same distortion is included in the input voltage, comparing the AC input currents of FIG. 15 and FIG. 16 confirms that the input current distortion rate is greatly reduced by suppressing the current fluctuation.

According to the embodiment of the converter of the present invention, the input current to the single-phase converter is controlled based on the command value from the DC constant voltage control system, and the input voltage fluctuates according to the control of the present invention. Even when _ed ', _eq ' added to the output of the PI controller for current control changes according to fluctuations in the input voltage, harmonics are included in the sudden change in the AC input voltage or in the input voltage. Even in this case, the voltage on the AC input side of the power converter can be changed in the same manner as the AC input voltage, and the transient fluctuation can be suppressed without waiting for the response of the PI controller.

  In addition, according to the phase shifter of the 90 ° advance circuit included in the power conversion device of the present invention, even when the input voltage contains harmonics by using the frequency characteristics having the low-pass filter characteristics, By removing the harmonics and detecting the voltage phase of the input voltage, errors in phase detection can be reduced, and current fluctuation after power conversion can be reduced.

  According to the power conversion device of the present invention, even when the quality of the input power supply is low, the operation rate of the device connected to this power supply is stabilized by stabilizing the output voltage and suppressing fluctuations in the output current. Can be improved.

  According to the power conversion device of the present invention, since fluctuations in the output current can be suppressed, it is possible to design the power conversion unit with a reduced overcurrent capability, and it is easy to reduce the size and cost.

  The present invention is not limited to the embodiments described above. Various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

  The current control unit of the power conversion device of the present invention can be performed with a digital signal and can perform software output on a computer.

  Moreover, a high power factor AC / DC converter can be comprised by connecting a DC / DC converter in the back | latter stage of the power converter device of this invention.

  Moreover, an uninterruptible power supply apparatus can be comprised by using the converter by the power converter device of this invention as a charging device of a storage battery, and making an electrical storage apparatus and a reverse conversion apparatus in a back | latter stage.

It is a figure for demonstrating schematic structure of the power converter device 1 of this invention. It is a figure for demonstrating the example of 1 structure of the power converter device of this invention. This is a configuration example of a 90 ° advance circuit using a general operational amplifier. It is a figure for demonstrating the circuit structure of the 90 degrees advance circuit with which the power converter device of this invention is provided. It is a figure for demonstrating the circuit structure of the 90 degree delay circuit with which the power converter device of this invention is provided. It is a figure which shows the frequency characteristic of the 90 degree advance circuit with which the power converter device of this invention is provided. It is a figure for demonstrating the input-output relationship of a converter. It is a figure for demonstrating the relationship between a stationary coordinate system and a rotation coordinate system. It is a figure for demonstrating the low-pass filter characteristic of a 90 degree phase advance circuit. It is a figure which shows the current control block which carries out current control of the converter. It is a figure for demonstrating the command value of electric current control. It is a figure for demonstrating the output generation of a PWM pulse. It is a figure which shows the change of an alternating current input current when an input voltage changes suddenly, and the change of a direct-current output voltage. It is a figure which shows the change of an alternating current input current when an input voltage changes suddenly, and the change of a direct-current output voltage. It is a figure which shows the change of alternating current input current with respect to distortion of input voltage. It is a figure which shows the change of alternating current input current with respect to distortion of input voltage. It is a figure for demonstrating the outline | summary of the control aspect of the conventional AC / DC converter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power converter 2 Power supply 2A AC power supply 2B DC power supply 3 Single phase converter 3a-3d Switch element 3a-3d Each switch element 4 Load 5 Inverter 11 Coordinate conversion part 11A, 11B Rotation coordinate conversion means 12 Coordinate conversion part 13 Rotation coordinate system Control unit 14 Current control means 14a Controller 14b Controller 14c Controller 14d Specified voltage setting means 14e Multiplier 14f Multiplier 15 Current fluctuation suppressing means 16 Phase shifter 16A circuit 16B circuit 17 Phase detection section 18 Converter control section 18a Carrier triangular wave signal Generation means 18b Control pulse generation means 19 Inverter control section 21 Detector 21A Current detection means 21B Voltage detection means 22 Detector 30 Subtractor 31 Subtractor 32 Subtractor 33 Subtractor 34 Adder 40 Circuit 41 Phase inversion circuit 42 Circuit 102 AC power Source 103 Converter 104 Load 114 Control circuit 118 Converter control unit 121 Detector 122 Detector C ₁ capacitor C ₂ capacitor

Claims (8)

In a power conversion method in which a single-phase power converter is current-controlled in a rotating coordinate system and power conversion is performed between single-phase AC power and DC power,
Form a voltage control value to control the single-phase converter by current control using the input current value of the single-phase power converter converted to the rotating coordinate system,
Bias the input voltage component of the single-phase converter converted to the rotary coordinate system to the voltage control value,
A power conversion method characterized by controlling a single phase converter using the voltage control value. In a power conversion method for current control of a single-phase converter in a rotating coordinate system and converting single-phase AC power to DC power,
Converting the input current value to the single-phase converter into a rotating coordinate system, forming a voltage control value for controlling the single-phase converter by controlling the input current value of the rotating coordinate system,
Convert the input voltage to the single-phase converter into a rotating coordinate system,
Add the input voltage of the single-phase converter converted to the rotating coordinate system to the voltage control value,
A power conversion method, wherein a single-phase converter is controlled using the added voltage control value. A single-phase converter that converts single-phase AC power into DC power;
A rotating coordinate system control unit for performing current control in the rotating coordinate system;
A first coordinate conversion unit that converts a voltage value and a current value of a stationary coordinate system into a rotating coordinate system;
A second coordinate converter that converts the voltage value of the rotating coordinate system into a stationary coordinate system;
A phase shifter that shifts the phase of the detected value of the voltage and current of the single-phase alternating current by + 90 ° or -90 °,
The first coordinate conversion unit inputs a single-phase AC input current value and a current value obtained by shifting the input current value by 90 ° by the phase shifter, and converts the input current value into a current value of a rotating coordinate system,
The rotating coordinate system control unit includes a current control unit configured to control a current value of the rotating coordinate system converted by the first coordinate converting unit to form a voltage control value of the rotating coordinate system;
Current fluctuation suppressing means for adding the input voltage input to the single-phase converter to the voltage control value and suppressing current fluctuation due to input voltage fluctuation;
The second coordinate conversion unit converts the voltage command value of the rotating coordinate system output from the rotating coordinate system control unit into a voltage command value of the stationary coordinate system,
The single-phase converter performs power conversion from AC power to DC power based on a voltage command value of a stationary coordinate system output from the second coordinate conversion unit . The said current fluctuation suppression means adds the voltage value of the rotating coordinate system converted by the said 1st coordinate conversion part to the voltage control value which the said current control means outputs, The Claim 3 characterized by the above-mentioned. Power conversion device. The current control means includes
The q-axis command current in the rotating coordinate system is set to zero, and the d-axis command current in the rotating coordinate system is set to a value obtained by PI control in which the deviation between the output voltage of the single-phase PFC converter and the voltage command value is set to zero. The power converter according to claim 3, wherein PI control is performed. The phase shifter is a 90 ° advance circuit using an operational amplifier,
The feedback resistor of the operational amplifier is configured as a parallel circuit of a first capacitor and a series resistor whose connection point is grounded via a second capacitor,
6. The resistor and the capacitor according to any one of claims 3 to 5, wherein the frequency characteristic of the phase shifter is a value having a predetermined gain at a predetermined frequency and a phase shift of 90 degrees. The power converter device as described in any one. Phase detection means for detecting the phase angle of the input voltage of single-phase AC power,
The phase detection means detects the phase angle of the input voltage with reference to the zero point of the low-pass filter output by the phase shifter,
The first coordinate conversion unit and the second coordinate conversion unit perform coordinate conversion using the phase angle of the input voltage detected by the phase detection unit as an operation parameter. The power conversion device according to one. The single-phase converter is a single-phase bridge circuit formed by bridge-connecting a switch element in which a self-extinguishing element and a diode are connected in parallel between an input terminal and an output terminal,
The power converter according to any one of claims 3 to 7, wherein AC power is converted into DC power by performing open / close control of each switch element in accordance with the voltage command value.