Control device, power conversion device, control method for power conversion device, and program

Abstract

A control device according to the present disclosure includes: a first conversion unit that performs two-phase three-phase conversion of a positive-phase d-axis current command value and a positive-phase q-axis current command value and outputs positive-phase current command values of three phases; a second conversion unit that performs two-phase three-phase conversion of a reverse-phase d-axis current command value and a reverse-phase q-axis current command value and outputs a reverse-phase current command values of three phases; an addition unit that adds the three-phase positive-phase current command values and the three-phase reverse-phase current command values and outputs current command values of three phases; an inverter control unit that controls an inverter on the basis of the three-phase current command values; and an amplitude correction unit. The amplitude correction unit calculates amplitude values of three phases from the positive-phase d-axis current command value, the positive-phase q-axis current command value, the reverse-phase d-axis current command value, and the reverse-phase q-axis current command value, and performs correction so that the amplitude of the three-phase current command values does not exceed a prescribed value when a maximum amplitude value among the amplitude values of three phases exceeds a predetermined prescribed value.

Description

Control device, power conversion device, and control method and program for power conversion device

[0001] The present disclosure relates to a control device, a power conversion device, a control method for a power conversion device, and a program.

[0002] Patent Document 1 discloses a power conversion device including a power conversion circuit configured to convert DC power into three-phase AC power in accordance with a switching control signal and a power conversion control circuit. The power conversion control circuit calculates a positive-phase current command signal based on a positive-phase voltage of a three-phase AC output voltage and a positive-phase current of a three-phase AC output current. The power conversion control circuit performs dq transformation on each of the measured values ​​of the three-phase AC output voltage and the three-phase AC output current. This calculates a first-axis negative-phase-sequence voltage value which is the d-axis component of the negative-phase-sequence voltage, a second-axis negative-phase-sequence voltage value which is the q-axis component of the negative-phase-sequence voltage, a first-axis negative-phase-sequence current value which is the d-axis component of the negative-phase-sequence current, and a second-axis negative-phase-sequence current value which is the q-axis component of the negative-phase-sequence current. The power conversion control circuit calculates a first-axis negative-phase-sequence current command value which is a d-axis component command of the negative-phase-sequence current based on the second-axis negative-phase-sequence voltage value, and calculates a second-axis negative-phase-sequence current command value which is a q-axis component command of the negative-phase-sequence current based on the first-axis negative-phase-sequence voltage value. The power conversion control circuit calculates a negative-sequence current command signal based on the first-axis negative-sequence current command value, the second-axis negative-sequence current command value, the first-axis negative-sequence current value, and the second-axis negative-sequence current value, and generates a switching control signal based on the positive-sequence current command signal and the negative-sequence current command signal.

[0003] Japanese Patent No. 6819818

[0004] In Patent Document 1, a signal obtained by adding a positive-phase current command signal and a negative-phase current command signal is used as a current command value for controlling a power conversion circuit. In this case, depending on the phase relationship between the positive and negative phases, the amplitude of the current command value after the addition may be excessively large.

[0005] An object of the present disclosure is to provide a control device, a power conversion device, a control method for a power conversion device, and a program that can limit the amplitude of a current command value to an arbitrary value.

[0006] a second conversion unit that performs two-phase to three-phase conversion between a negative-phase d-axis current command value and a negative-phase q-axis current command value and outputs the three-phase positive-phase current command values; an adder that adds the three-phase positive-phase current command values ​​and the three-phase negative-phase current command values ​​and outputs the three-phase current command values; an inverter control unit that controls an inverter based on the three-phase current command values; and an amplitude correction unit that calculates three-phase amplitude values ​​from the positive-phase d-axis current command value, the positive-phase q-axis current command value, the negative-phase d-axis current command value, and the negative-phase q-axis current command value, and when a maximum amplitude value among the three-phase amplitude values ​​exceeds a predetermined value, corrects the amplitudes of the three-phase current command values ​​so that they do not exceed the predetermined value.

[0007] A control method for a power conversion device according to the present disclosure includes: performing two-phase to three-phase conversion of a positive-phase d-axis current command value and a positive-phase q-axis current command value, and outputting three-phase positive-phase current command values; performing two-phase to three-phase conversion of a negative-phase d-axis current command value and a negative-phase q-axis current command value, and outputting the three-phase negative-phase current command values; adding the three-phase positive-phase current command values ​​and the three-phase negative-phase current command values ​​to output the three-phase current command values; controlling an inverter based on the three-phase current command values; calculating three-phase amplitude values ​​from the positive-phase d-axis current command value, the positive-phase q-axis current command value, the negative-phase d-axis current command value, and the negative-phase q-axis current command value; and, when a maximum amplitude value of the three-phase amplitude values ​​exceeds a predetermined specified value, performing a correction so that the amplitudes of the three-phase current command values ​​do not exceed the specified value.

[0008] A program according to the present disclosure is a program executed by a processor of a control device that controls a power conversion device, and the program is configured to cause the processor to execute the following: perform two-phase to three-phase conversion of a positive-phase d-axis current command value and a positive-phase q-axis current command value, and output three-phase positive-phase current command values; perform two-phase to three-phase conversion of a negative-phase d-axis current command value and a negative-phase q-axis current command value, and output the three-phase negative-phase current command values; add the three-phase positive-phase current command values ​​and the three-phase negative-phase current command values ​​to output the three-phase current command values; control an inverter based on the three-phase current command values; calculate three-phase amplitude values ​​from the positive-phase d-axis current command value, the positive-phase q-axis current command value, the negative-phase d-axis current command value, and the negative-phase q-axis current command value; and, when a maximum amplitude value of the three-phase amplitude values ​​exceeds a predetermined specified value, perform correction so that the amplitudes of the three-phase current command values ​​do not exceed the specified value.

[0009] In the control device power conversion device control method and program according to the present disclosure, correction is performed so that the amplitudes of the three-phase current command values ​​do not exceed specified values, thereby limiting the amplitudes of the current command values ​​to any desired value.

[0010] FIG. 1 is a diagram illustrating a configuration of a power conversion device according to embodiment 1. FIG. 2 is a diagram illustrating a configuration of a control device according to embodiment 1. FIG. 3 is a flowchart showing a method for correcting the amplitude of three-phase current command values ​​according to embodiment 1. FIG. 4 is a diagram illustrating a configuration of a control device according to a comparative example. FIG. 5 is a diagram illustrating an example of a hardware configuration of a processing circuit included in the control device according to embodiment 1. FIG. 6 is a diagram illustrating a configuration of a control device according to embodiment 2. FIG. 7 is a diagram illustrating a configuration of a control device according to embodiment 3. FIG. 8 is a diagram illustrating a configuration of a control device according to embodiment 4.

[0011] A control device, a power conversion device, a control method for a power conversion device, and a program according to each embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0012] First Embodiment. FIG. 1 is a diagram illustrating the configuration of a power conversion device 1 according to a first embodiment. The power conversion device 1 has an input terminal on the left side in FIG. 1 connected to a DC power source (not shown). The power conversion device 1 also has an output terminal on the right side in FIG. 1 connected to an AC power system (not shown). The power conversion device 1 converts DC power supplied from the DC power source into AC power and outputs the converted AC power to the AC power system. The power conversion device 1 in this embodiment is, for example, a power conversion device (PV-PCS: Photovoltaics-Power Conditioning System) for solar power generation (PV: Photovoltaics). In this case, the DC power source is, for example, a solar panel. The type of DC power source and the use of the power conversion device 1 are not limited.

[0013] The power conversion device 1 includes a DC switch 11, a DC capacitor 12, an inverter 13, an AC reactor 14, an AC capacitor 15, and an AC switch 16. The power conversion device 1 also includes a first current sensor 21, a first voltage sensor 22, a second current sensor 23, a second voltage sensor 24, a third current sensor 25, and a control device 30. Although the wiring of the control device 30 is omitted in Fig. 1, each element of the power conversion device 1 and the control device 30 are electrically connected.

[0014] The DC bus 2 connects the DC power source and the DC end of the inverter 13. The DC bus 2 supplies DC power to the inverter 13. On the DC bus 2, for example, a first current sensor 21, a DC switch 11, a first voltage sensor 22, and a DC capacitor 12 are arranged in this order from the DC power source toward the DC end of the inverter 13.

[0015] The AC circuit 3 connects the AC end of the inverter 13 to an AC power system. The AC circuit 3 is, for example, a three-phase, three-wire three-phase AC circuit. In a three-phase, three-wire three-phase AC circuit, three-phase AC power is supplied using three electric wires or cables, combining three systems of single-phase AC, with the current or voltage phases shifted from one another. The AC circuit 3 supplies the AC power converted by the inverter 13 to the AC power system. The AC circuit 3 includes, for example, a second current sensor 23, an AC reactor 14, an AC capacitor 15, an AC switch 16, a second voltage sensor 24, and a third current sensor 25, arranged in this order from the AC end of the inverter 13 toward the AC power system.

[0016] The AC power system is connected to the AC terminal of the inverter 13 via the AC circuit 3. The AC power system is also connected to a transformer (not shown). The AC power system is, for example, a system that integrates power generation, transformation, transmission, and distribution to supply AC power transformed by the transformer to power receiving equipment. The AC power system is connected to, for example, an unspecified load.

[0017] The DC switch 11 is a DC circuit breaker and is provided on the DC bus 2 between the first current sensor 21 and the first voltage sensor 22. The DC switch 11 connects or disconnects the DC bus 2 between the DC power supply and the inverter 13 in accordance with an on or off instruction from the control device 30 or an operator (not shown). When the DC switch 11 is opened, the DC power supplied from the DC power supply to the inverter 13 is cut off.

[0018] The DC capacitor 12 is provided on the DC bus 2 between the first voltage sensor 22 and the DC end of the inverter 13. The DC capacitor 12 is a smoothing capacitor that smoothes the DC voltage output from the DC power supply. When the DC switch 11 is closed, the voltage of the DC capacitor 12 is charged by DC power and rises, and when the DC switch 11 is open, the voltage of the DC capacitor 12 is discharged by a discharge circuit, a discharge resistor, etc. (not shown) and falls.

[0019] The inverter 13 has a DC end connected to the DC capacitor 12 and the DC switch 11 via the DC bus 2, and an AC end connected to the AC reactor 14. The inverter 13 is configured with a plurality of switching elements such as IGBTs (Insulated Gate Bipolar Transistors). The inverter 13 is controlled by, for example, a pulse width modulation signal that is a gate drive signal for the switching elements and is generated by a PWM (Pulse Width Modulation) control unit 65 (described later).

[0020] The inverter 13 receives DC power from a DC power source at one end, converts the received DC power into AC power under control of a pulse width modulation signal, and outputs the AC power from the other end, which is an output end, to be supplied to the AC power system. Note that the pulse width modulation signal will hereinafter also be referred to as a "PWM signal."

[0021] The AC reactor 14 is connected in series with the AC end of the inverter 13. The AC reactor 14 and, for example, an AC capacitor 15 connected in an L-shape via a branch point 15a, form an LC filter circuit. The LC filter circuit can reduce ripples that occur when the switching elements of the inverter 13 perform switching.

[0022] The AC capacitor 15 is an electronic component that stores and releases electric charge, and is connected in an L-type configuration to the AC reactor 14 via a branch point 15a. The AC capacitor 15 and the AC reactor 14 form a filter circuit, which can suppress harmonic currents from flowing out to the AC power grid.

[0023] The AC switch 16 is an AC circuit breaker and is provided in series between the AC capacitor 15 and the AC power system. The AC switch 16 connects or disconnects the AC circuit 3 between the inverter 13 and the AC power system in accordance with, for example, an on or off instruction from the control device 30 or an operator (not shown). When the AC switch 16 is opened, the AC power supplied from the inverter 13 to the AC power system is cut off.

[0024] The first current sensor 21 is, for example, a known DC ammeter or DC current sensor. The first current sensor 21 is disposed between the DC power supply and the DC switch 11, and detects the DC current i flowing from the DC power supply. ＤＣ The position where the first current sensor 21 is disposed is not limited to the position shown in FIG. ＤＣ The DC current i detected by the first current sensor 21 may be detected at any position. ＤＣ is acquired by the control device 30.

[0025] The first voltage sensor 22 is, for example, a known DC voltmeter or DC voltage sensor. The first voltage sensor 22 is disposed between the DC switch 11 and the DC capacitor 12, and detects the DC voltage v of the DC capacitor 12. ＤＣ The position where the first voltage sensor 22 is disposed is not limited to the position shown in FIG. ＤＣ The DC voltage v detected by the first voltage sensor 22 may be detected at any position. ＤＣ is acquired by the control device 30.

[0026] The second current sensor 23 is, for example, a known AC ammeter or AC current sensor. The second current sensor 23 is disposed between the inverter 13 and the AC reactor 14, and detects the inverter output current i, which is the output current of the inverter 13 and is a three-phase AC current. ＡＣ The position where the second current sensor 23 is disposed is not limited to the position shown in FIG. 1 , and the value of the inverter output current i ＡＣ The second current sensor 23 may be located at any position where the value of the inverter output current i ＡＣ is acquired by the control device 30.

[0027] The second voltage sensor 24 is, for example, a known AC voltmeter or AC voltage sensor. The second voltage sensor 24 is disposed between the AC switch 16 and the AC power system, and detects a system voltage v Ｇｒｉｄ The position where the second voltage sensor 24 is disposed is not limited to the position shown in FIG. ＧｒｉｄThe voltage sensor 24 may be located at any position where the value of the grid voltage v Ｇｒｉｄ is acquired by the control device 30.

[0028] The third current sensor 25 is, for example, a known AC ammeter or AC current sensor. The third current sensor 25 is disposed between the AC switch 16 and the AC power system, and detects a system current i, which is a three-phase AC current flowing in the AC power system. Ｇｒｉｄ The position where the third current sensor 25 is disposed is not limited to the position shown in FIG. Ｇｒｉｄ The third current sensor 25 may be located at any position where the value of the grid current i Ｇｒｉｄ is acquired by the control device 30.

[0029] The control device 30 controls the power conversion device 1. The control device 30 is provided, for example, inside or outside the power conversion device 1, and is connected to each component of the power conversion device 1, including the inverter 13, by wire or wirelessly. The control device 30 may be realized as a function of an inverter control circuit (not shown). The control device 30 may operate, for example, according to instructions from a higher-level device (not shown) or instructions from an operator via an operation unit (not shown). The higher-level device, for example, monitors and controls multiple power conversion devices 1 in an integrated manner, and is connected to each power conversion device 1 by wire or wirelessly.

[0030] The control device 30 has the configuration or functions of a PLL (Phase Locked Loop) control unit 41, a conversion unit 42, a conversion unit 43, and a power control unit 31. The control device 30 also has the configuration or functions of an MPPT (Maximum Power Point Tracking) control unit 55, a subtraction unit 56, and a DC voltage control unit 57. The control device 30 also has the configuration or functions of an adder 61, a conversion unit 32, a conversion unit 33, an integrator 34, a subtraction unit 63, a current control unit 64, and a PWM control unit 65.

[0031] The PLL control unit 41 is connected to the second voltage sensor 24 and the conversion units 42 and 43. The PLL control unit 41 detects the system voltage v ＧｒｉｄThe PLL control unit 41 acquires information on the system voltage v Ｇｒｉｄ PLL control is performed based on the system voltage v Ｇｒｉｄ The information on the reference phase θ synchronized with the phase difference θ is output to the converters 42 and 43 .

[0032] The converter 42 is connected to the second voltage sensor 24, the PLL controller 41, and the power controller 31. The converter 42 converts the system voltage v Ｇｒｉｄ and information on the reference phase θ output from the PLL control unit 41. The conversion unit 42 performs three-phase to two-phase conversion based on the acquired reference phase θ, and converts the system voltage v Ｇｒｉｄ into a positive-phase d-axis voltage value and a positive-phase q-axis voltage value. Three-phase to two-phase transformation is also called dq transformation. Note that the reference phase θ of the dq transformation is, for example, set so that the q-axis voltage component is 0. The transformation unit 42 outputs information on the value of the positive-phase d-axis voltage and information on the value of the positive-phase q-axis voltage to the power control unit 31.

[0033] The converter 42 is further connected to the second current sensor 23, the third current sensor 25, and the power control unit 31. The converter 42 converts the inverter output current i ＡＣ and the grid current i Ｇｒｉｄ and information on the reference phase θ output from the PLL control unit 41. The conversion unit 42 performs three-phase to two-phase conversion based on the acquired reference phase θ, and converts the inverter output current i ＡＣ and grid current i Ｇｒｉｄ and the positive-phase d-axis current value are converted into a positive-phase d-axis current value and a positive-phase q-axis current value, respectively. Note that the reference phase θ of the dq transformation is, for example, set so that the q-axis voltage component is 0. The conversion unit 42 outputs information on the value of the positive-phase d-axis current and information on the value of the positive-phase q-axis current to the power control unit 31. The value of the positive-phase d-axis current of the inverter output current corresponds to a positive-phase d-axis current measurement value Ipd_fbk, which will be described later, and the value of the positive-phase q-axis current corresponds to a positive-phase q-axis current measurement value Ipq_fbk, which will be described later.

[0034] The converter 43 is connected to the second voltage sensor 24, the PLL controller 41, and the power controller 31. The converter 43 converts the system voltage v Ｇｒｉｄ and information on the reference phase θ output from the PLL control unit 41. The conversion unit 43 performs three-phase to two-phase conversion based on the acquired reference phase θ, and converts the system voltage v Ｇｒｉｄinto the negative-phase-sequence d-axis voltage value and the negative-phase-sequence q-axis voltage value. The converter 43 outputs the information on the negative-phase-sequence d-axis voltage value and the information on the negative-phase-sequence q-axis voltage value to the power controller 31.

[0035] The converter 43 is further connected to the second current sensor 23, the third current sensor 25, and the power control unit 31. The converter 43 converts the inverter output current i ＡＣ and the grid current i Ｇｒｉｄ and information on the reference phase θ output from the PLL control unit 41. The conversion unit 43 performs three-phase to two-phase conversion based on the acquired reference phase θ, and converts the inverter output current i ＡＣ and grid current i Ｇｒｉｄ and the negative-phase-sequence d-axis current value and the negative-phase-sequence q-axis current value are converted by converter 43. Converter 43 outputs information on the negative-phase-sequence d-axis current value and information on the negative-phase-sequence q-axis current value to power controller 31. The value of the negative-phase-sequence d-axis current of the inverter output current corresponds to a negative-phase-sequence d-axis current measurement value Ind_fbk, which will be described later, and the value of the negative-phase-sequence q-axis current corresponds to a negative-phase-sequence q-axis current measurement value Inq_fbk, which will be described later.

[0036] Power control unit 31 is connected to converters 42 and 43, adder 61, and converters 32 and 33. Power control unit 31 acquires information on the values ​​of a positive-phase d-axis voltage, a positive-phase q-axis voltage, a positive-phase d-axis current, and a positive-phase q-axis current from converter 42. Power control unit 31 further acquires information on the values ​​of a negative-phase d-axis voltage, a negative-phase q-axis voltage, a negative-phase d-axis current, and a negative-phase q-axis current from converter 43. Based on the acquired information, power control unit 31 may determine values ​​of a positive-phase d-axis current command value Ipq_ref, a negative-phase d-axis current command value Ind_ref, and a negative-phase q-axis current command value Inq_ref, which will be described later.

[0037] The MPPT control unit 55 is connected to the first current sensor 21, the first voltage sensor 22, and the subtraction unit 56. The MPPT control unit 55 calculates the DC current i ＤＣ and the DC voltage v detected by the first voltage sensor 22. ＤＣ The MPPT control unit 55 acquires the information of the acquired DC current i ＤＣ Information on DC voltage V ＤＣBased on the information, for example, MPPT control based on the known hill-climbing method is performed to obtain the DC voltage command value v ＊ ＤＣ The limiter range of the MPPT control by the MPPT control unit 55 is determined for each device, for example.

[0038] The subtraction unit 56 is connected to the first voltage sensor 22 and the MPPT control unit 55. The subtraction unit 56 calculates the DC voltage v ＤＣ and the DC voltage command value v output from the MPPT control unit 55. ＊ ＤＣ The subtraction unit 56 obtains the DC voltage command value v ＊ ＤＣ DC voltage V ＤＣ The subtraction unit 56 outputs information about the calculated value to the DC voltage control unit 57.

[0039] The DC voltage control unit 57 is connected to the subtraction unit 56 and the addition unit 61. The DC voltage control unit 57 receives the DC voltage command value v ＊ ＤＣ DC voltage V ＤＣ The DC voltage control unit 57 controls the acquired information to calculate a positive-phase d-axis current command value. The DC voltage control unit 57 outputs information on the calculated positive-phase d-axis current command value to the adder 61.

[0040] The adder 61 is connected to the power control unit 31, the DC voltage control unit 57, and the converter 32. The adder 61 acquires information on the d-axis current command value output from the power control unit 31 and information on the d-axis current command value output from the DC voltage control unit 57. The adder 61 calculates a value obtained by adding the acquired d-axis current command values. The adder 61 outputs information on the added value to the converter 32 as a positive-phase d-axis current command value Ipd_ref.

[0041] Next, a method for calculating current command values ​​for three phases, U, V, and W, from the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref will be described with reference to Figures 1 to 3.

[0042] 1 , the converter 32 is connected to the power control unit 31, the adder 61, and the integrator 34. The converter 32 acquires information on the positive-phase q-axis current command value Ipq_ref output from the power control unit 31 and information on the positive-phase d-axis current command value Ipd_ref output from the adder 61. The converter 32 performs two-phase to three-phase conversion on the positive-phase d-axis current command value Ipd_ref and the positive-phase q-axis current command value Ipq_ref, and outputs three-phase positive-phase current command values.

[0043] The converter 33 is connected to the power control unit 31 and the integrator 34. The converter 33 acquires information on the negative-phase-sequence d-axis current command value Ind_ref and information on the negative-phase-sequence q-axis current command value Inq_ref output from the power control unit 31. The converter 33 performs two-phase to three-phase conversion on the negative-phase-sequence d-axis current command value Ind_ref and the negative-phase-sequence q-axis current command value Inq_ref, and outputs three-phase negative-phase-sequence current command values.

[0044] FIG. 2 is a diagram illustrating the configuration of the control device 30 according to the first embodiment. FIG. 2 illustrates the main components of the control device 30, with some components omitted. As shown in FIG. 2, an adder 35 is provided on the output side of the converters 32 and 33. The adder 35 adds the three-phase positive-phase current command values ​​and the three-phase negative-phase current command values ​​to output three-phase current command values. The three-phase current command values ​​are a U-phase current command value, a V-phase current command value, and a W-phase current command value. An integrator 34 is provided on the output side of the adder 35. The three-phase current command values ​​are input to the integrator 34.

[0045] Next, a method for correcting the amplitudes of the three-phase current command values ​​will be described. The power control unit 31 and the integrating unit 34 correspond to an amplitude correcting unit. The amplitude correcting unit calculates amplitude values ​​for three phases, i.e., the U phase, the V phase, and the W phase, from the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref. If the maximum amplitude value among the calculated three-phase amplitude values ​​exceeds a predetermined value, the amplitude correcting unit performs correction so that the amplitudes of the three-phase current command values ​​do not exceed the predetermined value. Specifically, the amplitude correcting unit performs correction by multiplying the three-phase current command values ​​output from the adding unit 35 by the reciprocal of the maximum amplitude value among the three-phase amplitude values.

[0046] FIG. 3 is a flowchart showing a method for correcting the amplitudes of three-phase current command values ​​according to the first embodiment. The amplitude calculation unit 31a of the power control unit 31 calculates three-phase amplitude values ​​from the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref (step 21). Specifically, the amplitude calculation unit 31a calculates the amplitudes of the U, V, and W phases. The amplitude calculation unit 31a then extracts the maximum amplitude value from the calculated three-phase amplitude values. Next, the comparison unit 31b of the power control unit 31 compares the maximum amplitude value with a specified value (step 22). The specified value is, for example, the rated value of the power conversion device 1. In the example of FIG. 2, the comparison unit 31b determines whether the maximum amplitude value exceeds 100%, assuming that the rated value is 100%. Note that the specified value is not limited to the rated value and may be set to any value.

[0047] If the maximum amplitude value is equal to or less than the specified value, the control is terminated. If the maximum amplitude value is greater than the specified value, the reciprocal calculation unit 31c of the power control unit 31 calculates the reciprocal of the maximum amplitude value and outputs it to the integrating unit 34 (step 23). The integrating unit 34 multiplies each of the three-phase current command values ​​by the reciprocal of the maximum amplitude value, and outputs the result as the corrected three-phase current command values ​​(step 24). This completes the correction of the amplitudes of the three-phase current command values.

[0048] Next, a method for calculating the three-phase amplitude values ​​will be described in detail. The three-phase current command values ​​can be expressed by Equation 1 using an inverse transformation formula for two-phase to three-phase transformation.

[0049]

[0050] where Iu, Iv, and Iw are three-phase current command values, Ipu, Ipv, and Ipw are three-phase positive-phase current command values, and Inu, Inv, and Inw are three-phase negative-phase current command values. ipd is a positive-phase d-axis current command value, ipq is a positive-phase q-axis current command value, ind is a negative-phase d-axis current command value, and inq is a negative-phase q-axis current command value. By converting Equation 1, the following Equation 2 is obtained.

[0051]

[0052] By using Equation 2, the amplitude values ​​of the three phases, U, V, and W, can be calculated from the positive-phase d-axis current command value ipd, the positive-phase q-axis current command value ipq, the negative-phase d-axis current command value ind, and the negative-phase q-axis current command value inq.

[0053] 1 and 2 differ in the number and location of integrators 34. In FIG. 1, integrators 34 are provided separately on the output sides of converters 32 and 33. In this manner, the amplitude correction unit may perform correction by multiplying the three-phase positive-sequence current command values ​​output by converter 32 and the three-phase negative-sequence current command values ​​output by converter 33 by the reciprocals of the maximum amplitude values. After multiplying the reciprocals, the corrected three-phase positive-sequence current command values ​​and the corrected three-phase negative-sequence current command values ​​are added by subtractor 63. This method also makes it possible to correct the amplitudes of the three-phase current command values ​​in a manner similar to that of the configuration in FIG. 2.

[0054] Next, the control of the inverter 13 using the corrected three-phase current command values ​​will be described with reference to Fig. 1. The subtraction unit 63 is connected to the second current sensor 23 and the integration unit 34. The subtraction unit 63 calculates the inverter output current i ＡＣ and the corrected three-phase current command value i ＊ ＡＣ As described above, the subtractor 63 acquires the corrected three-phase current command value i ＊ ＡＣ Instead of the three-phase current command values ​​i, the corrected three-phase positive-sequence current command values ​​and the corrected three-phase negative-sequence current command values ​​may be input. ＊ ＡＣ from inverter output current i ＡＣ The subtraction unit 63 outputs information about the calculated value to the current control unit 64.

[0055] The current control unit 64 is connected to the subtraction unit 63 and the PWM control unit 65. The current control unit 64 acquires information on the value output from the subtraction unit 63. The current control unit 64 controls the acquired information to calculate a voltage command value. The current control unit 64 outputs the calculated voltage command value to the PWM control unit 65.

[0056] The PWM control unit 65 is connected to the inverter 13 and the current control unit 64. The PWM control unit 65 acquires a voltage command value from the current control unit 64. The PWM control unit 65 performs PWM control based on the acquired voltage command value and generates a gate signal, which is a PWM signal. The PWM control unit 65 outputs the generated gate signal to the inverter 13 and controls the switching elements of the inverter 13 to comprehensively control the operation of the inverter 13. The PWM control unit 65 is an example of an inverter control unit that controls the inverter 13 based on three-phase current command values.

[0057] 4 is a diagram illustrating the configuration of a control device 830 according to a comparative example. The control device 830 according to the comparative example differs from the control device 30 according to the present embodiment in that amplitude correction is not performed. In this case, depending on the phase relationship between the positive and negative phase current command values, the amplitude of the three-phase current command values ​​after summing may become excessive. In other words, since the comparative example does not take into account the amplitude after summing the positive and negative phases, there is a possibility that a value exceeding the rated value may be output.

[0058] In contrast, in this embodiment, the amplitude values ​​of the three-phase current command values ​​are calculated from the positive-phase current command value and the negative-phase current command value. Then, if the current of the phase with the largest amplitude value among the three phases exceeds a specified value, the current command value can be corrected so that the current of the phase with the largest amplitude value matches the specified value. Therefore, the amplitude of the current command value can be limited to an arbitrary value. Furthermore, since the power conversion device 1 of this embodiment can use both the positive phase and the negative phase, this embodiment can also be applied to a system that requires a negative phase output, for example.

[0059] In the present embodiment, the correction is performed so that the current of the phase having the largest amplitude value coincides with the specified value. However, the present invention is not limited to this, and it is sufficient if the correction is performed based on the calculated three-phase amplitude values ​​so that the amplitudes of the three-phase current command values ​​do not exceed the specified value.

[0060] In the present embodiment, the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref have been described as being set based on measured values. However, the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref may be stored in advance by the power control unit 31 or the control device 30. The positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative d-axis current command value Ind_ref, and the negative q-axis current command value Inq_ref may be output by the power control unit 31 in response to a command from outside the power conversion device 1.

[0061] Furthermore, feedback control may be performed to cancel the difference between the positive-phase d-axis current command value Ipd_ref and the positive-phase d-axis current measurement value Ipd_fbk. A PI compensator may be used for the feedback control. In this case, the positive-phase d-axis current command value Ipd_ref shown in FIG. 2 may be a signal after feedback control. Similarly, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref may be signals after feedback control.

[0062] 5 is a diagram illustrating an example of the hardware configuration of a processing circuit included in the control device 30 according to the first embodiment. Each function of the control device 30 can be realized by the processing circuit. In one aspect, the processing circuit includes at least one processor 91 and at least one memory 92. In another aspect, the processing circuit includes at least one dedicated hardware 93.

[0063] When the processing circuit includes a processor 91 and a memory 92, each function is realized by software, firmware, or a combination of software and firmware. At least one of the software and firmware is written as a program. At least one of the software and firmware is stored in the memory 92. The processor 91 realizes each function by reading and executing the program stored in the memory 92. In other words, the control device 30 can also be realized by a computer and a program, and the program can be stored in a storage medium or provided over a network.

[0064] When the processing circuit includes dedicated hardware 93, the processing circuit may be, for example, a single circuit, a composite circuit, a programmed processor, or a combination of these. Each function may be realized by such hardware 93. Each function of the control device 30 may be partially or entirely configured by the hardware 93, or partially or entirely configured as a program executed by the processor 91.

[0065] It can be said that the program executed by the processor 91 is configured to cause the processor 91 to execute at least the following first to sixth processes. The first process is a process of performing two-phase to three-phase conversion on the positive-phase d-axis current command value Ipd_ref and the positive-phase q-axis current command value Ipq_ref to output three-phase positive-phase current command values. The second process is a process of performing two-phase to three-phase conversion on the negative-phase d-axis current command value Ind_ref and the negative-phase q-axis current command value Inq_ref to output three-phase negative-phase current command values. The third process is a process of adding the three-phase positive-phase current command values ​​and the three-phase negative-phase current command values ​​to output three-phase current command values. The fourth process is a process of controlling the inverter based on the three-phase current command values. The fifth process is a process for calculating three-phase amplitude values ​​from the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref. The sixth process is a process for correcting the amplitudes of the three-phase current command values ​​so that they do not exceed a predetermined value when the maximum amplitude value among the three-phase amplitude values ​​exceeds a predetermined value.

[0066] The processor 91 may be, for example, a central processing unit (CPU), a reduced instruction set computer (RISC), a digital signal processor (DSP), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or another processing unit, or may be a combination of two or more of these.

[0067] The memory 92 is a volatile or non-volatile storage medium such as a hard disk drive (HDD), a solid state drive (SSD), a dynamic random access memory (DRAM), or a semiconductor memory. The memory 92 may also be a combination of two or more of these. The memory 92 is connected to each unit of the control device 30 via, for example, a bus (not shown) so that various types of information can be input and output. The memory 92 stores, for example, programs required for the operation of each unit of the control device 30, and various types of information are written to and read from the memory 92 by each unit of the control device 30.

[0068] The memory 92 stores, for example, values ​​acquired by each sensor, such as the first current sensor 21. The memory 92 also stores, for example, the above-mentioned specified value, rated value, and programs for correcting amplitude. The memory 92 also stores, for example, calculation results by each unit, such as the power control unit 31. The memory 92 may be provided outside the control device 30 and connected to the control device 30 by wire or wirelessly, or may be an external storage medium, such as a memory card or a DVD (Digital Versatile Disc), or online storage.

[0069] The above-described modifications can be applied as appropriate to the control devices, power conversion devices, control methods for a power conversion device, and programs according to the following embodiments. Note that the control devices, power conversion devices, control methods for a power conversion device, and programs according to the following embodiments have many points in common with the first embodiment, so the following description will focus on the differences from the first embodiment.

[0070] Second Embodiment Fig. 6 is a diagram illustrating the configuration of a control device 230 according to a second embodiment. In the first embodiment, amplitude correction is performed after the conversion units 32 and 33. In contrast, the present embodiment differs from the first embodiment in that amplitude correction is performed before the conversion units 32 and 33. That is, in the present embodiment, an integrator 34 is provided on the input side of the conversion units 32 and 33. The other configurations are the same as those of the first embodiment.

[0071] As in the first embodiment, the power control unit 31 calculates three-phase amplitude values ​​from the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref (step 21). The amplitude calculation unit 31a further extracts the maximum amplitude value from the calculated three-phase amplitude values. Next, the comparison unit 31b of the power control unit 31 compares the maximum amplitude value with a specified value (step 22). If the maximum amplitude value is equal to or less than the specified value, the control is terminated. If the maximum amplitude value is greater than the specified value, the reciprocal calculation unit 31c of the power control unit 31 calculates the reciprocal of the maximum amplitude value and outputs it to the integrator 34 (step 23).

[0072] The integrator 34 multiplies each of the positive-phase d-axis current command value Ipd_ref and the positive-phase q-axis current command value Ipq_ref by the reciprocal of the maximum amplitude value, and outputs the result to the converter 32 (step 24). The integrator 34 also multiplies each of the negative-phase d-axis current command value Ind_ref and the negative-phase q-axis current command value Inq_ref by the reciprocal of the maximum amplitude, and outputs the result to the converter 33 (step 24).

[0073] The converter 32 performs two-phase to three-phase conversion between the corrected positive-phase d-axis current command value Ipd_ref and the corrected positive-phase q-axis current command value Ipq_ref, and outputs three-phase positive-phase current command values. The converter 33 performs two-phase to three-phase conversion between the corrected negative-phase d-axis current command value Ind_ref and the corrected negative-phase q-axis current command value Inq_ref, and outputs three-phase negative-phase current command values. The adder 35 adds the three-phase positive-phase current command values ​​and the three-phase negative-phase current command values, and outputs three-phase current command values. This completes the correction of the amplitudes of the three-phase current command values.

[0074] The amplitude correction unit of this embodiment performs correction by multiplying the positive-phase d-axis current command value Ipd_ref, the positive-phase q-axis current command value Ipq_ref, the negative-phase d-axis current command value Ind_ref, and the negative-phase q-axis current command value Inq_ref by the reciprocal of the maximum amplitude value among the three-phase amplitude values. In this case, too, the amplitudes of the three-phase current command values ​​can be corrected, and the amplitudes of the current command values ​​can be limited to any value.

[0075] 7 is a diagram illustrating the configuration of a control device 330 according to the third embodiment. The control device 330 of this embodiment further includes an amplitude calculation unit 31 d, a subtraction unit 31 e, a PI compensator 31 f, and an integration unit 36 ​​in addition to the components of the control device 30 of the first embodiment. The other components are the same as those of the first embodiment.

[0076] The amplitude calculation unit 31d calculates feedback amplitude values, which are the amplitude values ​​of the three-phase current measurements, from the positive-phase d-axis current measurement value Ipd_fbk, the positive-phase q-axis current measurement value Ipq_fbk, the negative-phase d-axis current measurement value Ind_fbk, and the negative-phase q-axis current measurement value Inq_fbk. At this time, by using the above-mentioned Equation 2, the feedback amplitude values ​​for the three phases (U phase, V phase, and W phase) can be calculated from the positive-phase d-axis current measurement value ipd, the positive-phase q-axis current measurement value ipq, the negative-phase d-axis current measurement value ind, and the negative-phase q-axis current measurement value inq.

[0077] The subtractor 31e receives the amplitudes of the corrected three-phase current command values ​​and the three-phase feedback amplitude values. The amplitudes of the corrected three-phase current command values ​​are corrected by integrating the reciprocals of the maximum amplitude values ​​using the same calculation as in the first embodiment. The PI compensator 31f outputs a signal for further correcting the amplitudes of the three-phase current command values ​​so as to cancel out the difference between the amplitudes of the corrected three-phase current command values ​​and the feedback amplitude values. The integrator 36 integrates the signal from the PI compensator 31f with each of the corrected three-phase current command values ​​output from the integrator 34.

[0078] In this way, the amplitude correction unit of the present embodiment further corrects the amplitudes of the three-phase current command values ​​by feedback control so as to cancel out the difference between the amplitudes of the three-phase current command values ​​after correction by the integrator 34 and the feedback amplitude values. In this embodiment, in addition to the effect of the first embodiment, the control deviation can be canceled out by the feedback control using the PI compensator 31f.

[0079] 8 is a diagram illustrating the configuration of a control device 430 according to a fourth embodiment. The control device 430 of this embodiment further includes the amplitude calculation unit 31d, subtraction unit 31e, PI compensator 31f, and integration unit 36 ​​described in the third embodiment, in addition to the control device 230 of the second embodiment. The other configurations are the same as those of the second embodiment.

[0080] As in the third embodiment, the amplitude calculation unit 31d calculates a feedback amplitude value from the positive-phase d-axis current measurement value Ipd_fbk, the positive-phase q-axis current measurement value Ipq_fbk, the negative-phase d-axis current measurement value Ind_fbk, and the negative-phase q-axis current measurement value Inq_fbk. The feedback amplitude value is the amplitude value of the three-phase current measurement values.

[0081] The subtractor 31e receives the amplitudes of the corrected three-phase current command values ​​and the three-phase feedback amplitude values. The amplitudes of the corrected three-phase current command values ​​are corrected by integrating the reciprocals of the maximum amplitude values ​​using the same calculation as in the second embodiment. The PI compensator 31f outputs a signal for further correcting the amplitudes of the three-phase current command values ​​so as to cancel out the difference between the amplitudes of the corrected three-phase current command values ​​and the feedback amplitude values. The integrator 36 integrates the signal from the PI compensator 31f with each of the corrected three-phase current command values ​​output from the adder 35.

[0082] In this manner, in this embodiment, the amplitudes of the three-phase current command values ​​are further corrected by feedback control so as to cancel out the difference between the amplitudes of the three-phase current command values ​​after correction by integrating the reciprocals of the amplitude values ​​and the feedback amplitude values. In this embodiment as well, the control deviation can be canceled out by feedback control using the PI compensator 31f.

[0083] The technical features described in each embodiment may be used in appropriate combination.

[0084] REFERENCE SIGNS LIST 1 Power conversion device, 2 DC bus, 3 AC circuit, 11 DC switch, 12 DC capacitor, 13 Inverter, 14 AC reactor, 15 AC capacitor, 15a Branch point, 16 AC switch, 21 First current sensor, 22 First voltage sensor, 23 Second current sensor, 24 Second voltage sensor, 25 Third current sensor, 30 Control device, 31 Power control unit, 31a Amplitude calculation unit, 31b Comparison unit, 31c Reciprocal calculation unit, 31d Amplitude calculation unit, 31e Subtraction unit, 31f PI compensator, 32 Conversion unit, 33 Conversion unit, 34 Integration unit, 35 Addition unit, 36 Integration unit, 41 PLL control unit, 42 Conversion unit, 43 Conversion unit, 55 MPPT control unit, 56 Subtraction unit, 57 DC voltage control unit, 61 Addition unit, 63 Subtraction unit, 64 Current control unit, 65 PWM control unit, 91 Processor, 92 Memory, 93 Hardware, 230 Control device, 330 Control device, 430 Control device, 830 Control device

Claims

1. a first conversion unit that performs two-phase to three-phase conversion on the positive-phase d-axis current command value and the positive-phase q-axis current command value to output three-phase positive-phase current command values; a second conversion unit that converts the negative-phase-sequence d-axis current command value and the negative-phase-sequence q-axis current command value into two-phase to three-phase command values ​​and outputs the three-phase negative-phase current command values; an adder unit that adds the three-phase positive-sequence current command values ​​and the three-phase negative-sequence current command values ​​to output the three-phase current command values; an inverter control unit that controls an inverter based on the three-phase current command values; An amplitude correction unit; Equipped with The amplitude correction unit calculating the three-phase amplitude values ​​from the positive-phase d-axis current command value, the positive-phase q-axis current command value, the negative-phase d-axis current command value, and the negative-phase q-axis current command value; a control device that, when a maximum amplitude value among the amplitude values ​​of the three phases exceeds a predetermined specified value, corrects the amplitudes of the current command values ​​of the three phases so that they do not exceed the specified value.

2. 2. The control device according to claim 1, wherein the amplitude correction unit performs the correction by multiplying the three-phase current command values ​​by a reciprocal of the maximum amplitude value.

3. 2. The control device according to claim 1, wherein the amplitude correction unit performs the correction by multiplying the three-phase positive-sequence current command values ​​and the three-phase negative-sequence current command values ​​by reciprocals of the maximum amplitude values.

4. 2. The control device according to claim 1, wherein the amplitude correction unit performs the correction by multiplying the positive-phase d-axis current command value, the positive-phase q-axis current command value, the negative-phase d-axis current command value, and the negative-phase q-axis current command value by reciprocals of the maximum amplitude values, respectively.

5. The amplitude correction unit calculating a feedback amplitude value, which is an amplitude value of the three-phase current measurement values, from the positive-phase d-axis current measurement value, the positive-phase q-axis current measurement value, the negative-phase d-axis current measurement value, and the negative-phase q-axis current measurement value; 5. The control device according to claim 1, further comprising: correcting amplitudes of the three-phase current command values ​​so as to cancel a difference between the amplitudes of the corrected three-phase current command values ​​and the feedback amplitude values.

6. A control device according to any one of claims 1 to 4; The inverter; A power conversion device comprising:

7. A method for controlling a power conversion device, comprising: performing two-phase to three-phase conversion on the positive-phase d-axis current command value and the positive-phase q-axis current command value to output three-phase positive-phase current command values; performing two-phase to three-phase conversion on the negative-phase d-axis current command value and the negative-phase q-axis current command value, and outputting the three-phase negative-phase current command values; adding the three-phase positive-sequence current command values ​​and the three-phase negative-sequence current command values ​​to output the three-phase current command values; Controlling an inverter based on the three-phase current command values; calculating the three-phase amplitude values ​​from the positive-phase d-axis current command value, the positive-phase q-axis current command value, the negative-phase d-axis current command value, and the negative-phase q-axis current command value; When a maximum amplitude value among the amplitude values ​​of the three phases exceeds a predetermined specified value, a correction is performed so that the amplitudes of the current command values ​​of the three phases do not exceed the specified value. A method for controlling a power conversion device comprising:

8. A program executed by a processor of a control device that controls a power conversion device, The program causes the processor to: performing two-phase to three-phase conversion on the positive-phase d-axis current command value and the positive-phase q-axis current command value to output three-phase positive-phase current command values; performing two-phase to three-phase conversion on the negative-phase d-axis current command value and the negative-phase q-axis current command value, and outputting the three-phase negative-phase current command values; adding the three-phase positive-sequence current command values ​​and the three-phase negative-sequence current command values ​​to output the three-phase current command values; Controlling an inverter based on the three-phase current command values; calculating the three-phase amplitude values ​​from the positive-phase d-axis current command value, the positive-phase q-axis current command value, the negative-phase d-axis current command value, and the negative-phase q-axis current command value; When a maximum amplitude value among the amplitude values ​​of the three phases exceeds a predetermined specified value, a correction is performed so that the amplitudes of the current command values ​​of the three phases do not exceed the specified value. A program configured to cause a computer to execute the above steps.