Power converter and control method for power converter

Abstract

The present invention provides a power converter and a control method for the power converter that can suppress errors in tracking control caused by the transmission characteristics of the output target. [Solution] This power converter 100 comprises a power conversion unit 10 that converts and outputs the input power, and a control unit 11 that controls the power conversion by the power conversion unit 10. The control unit 11 includes a command value generation unit 20, a phase correction unit 40, and a tracking signal output unit 50. The phase correction unit 40 calculates a command value I based on a phase correction amount δ calculated based on at least one of the output current Ia and a transfer function generated based on a model of the AC system 250. * Correct the phase.

Description

[Technical Field]

[0001] This invention relates to a power converter and a method for controlling a power converter, and more particularly to a power converter and a method for controlling a power converter that corrects the phase of a command value. [Background technology]

[0002] Conventionally, power conversion devices that correct the phase of command values ​​are known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a power converter that is connected to a power system and performs control to compensate for reactive power and harmonic power of the power system. This power converter corrects the detection phase of the voltage of the power system by a phase correction amount that is set in advance based on the detection time delay of the detector and the control calculation time delay in the control unit. In Patent Document 1, the corrected phase is used as the reference phase when generating the output current command value of the power converter, thereby suppressing errors in tracking control caused by the detection time delay of the detector and the control calculation time delay in the control unit. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2008-234298 [Overview of the project] [Problems that the invention aims to solve]

[0005] In power conversion devices like the one described in Patent Document 1, tracking control errors can occur not only due to delays in the detector detection time and control calculation time within the control unit, but also due to the transmission characteristics of the power system (output target). However, the power conversion device described in Patent Document 1 cannot suppress tracking control errors caused by the transmission characteristics of the output target. Therefore, there is a need for a power conversion device and a control method for a power conversion device that can suppress tracking control errors caused by the transmission characteristics of the output target.

[0006] This invention was made to solve the above-mentioned problems, and one objective of this invention is to provide a power converter and a control method for a power converter that can suppress errors in tracking control caused by the transmission characteristics of the output target. [Means for solving the problem]

[0007] To achieve the above objective, a power conversion device according to the first aspect of this invention comprises a power conversion unit that converts input power and outputs it to an output target, and a control unit that controls the power conversion by the power conversion unit, wherein the control unit includes a command value generation unit that generates a command value of the output current to be output to the outside, a phase correction unit that corrects the phase of the command value generated by the command value generation unit, and a tracking signal output unit that outputs a signal for controlling the output current to follow a corrected command value which is a command value whose phase has been corrected by the phase correction unit, wherein the phase correction unit corrects the phase of the command value based on a phase correction amount calculated based on at least one of the output current and a transfer function generated based on a model of the output target.

[0008] In the power conversion device according to the first aspect of this invention, as described above, the phase correction unit corrects the phase of the command value based on a phase correction amount calculated based on at least one of the output current and the transfer function generated based on the model of the output target. Here, the output current and the transfer function generated based on the model of the output target reflect the phase shift caused by the transfer characteristics of the output target. Therefore, by correcting the phase of the command value based on a phase correction amount calculated based on at least one of the output current and the transfer function generated based on the model of the output target as described above, the phase of the command value can be corrected based on a phase correction amount that includes the phase shift caused by the transfer characteristics of the output target. As a result, errors in tracking control caused by the transfer characteristics of the output target can be suppressed.

[0009] In the power conversion device according to the first aspect described above, preferably, the output target includes a power system, and the command value generation unit generates a command value based on the voltage in the power system and the output current. With this configuration, the power factor in the power system can be calculated based on the voltage in the power system and the output current of the power conversion device, so a command value for controlling the power factor in the power system to a desired value can be easily generated.

[0010] In the power conversion device according to the first phase described above, preferably, the phase correction unit calculates the phase correction amount based on the delay of the output current relative to the command value. With this configuration, the phase of the error in the tracking control that actually occurs can be accurately corrected.

[0011] In this case, preferably, the phase correction unit is configured to update the phase correction amount at predetermined intervals. With this configuration, even if the error in the tracking control changes over time, the phase correction amount can be updated in real time in accordance with the temporal change in the delay of the output current relative to the command value.

[0012] In the power conversion device according to the first aspect described above, preferably, the phase correction unit corrects the phase of the command value by calculating the sine and cosine of the phase correction amount based on the output current and the command value. With this configuration, the phase of the command value can be easily corrected by directly substituting the calculated sine and cosine of the phase correction amount into the calculation formula for correcting the phase of the command value.

[0013] In the power conversion device according to the first aspect described above, preferably, the transfer function includes a loop transfer function, and the phase correction unit calculates the phase correction amount based on the amount of phase shift from the initial phase of the phase corresponding to the operating frequency in the loop transfer function. With this configuration, the phase correction amount can be calculated in advance by generating the loop transfer function in advance based on the model of the output target.

[0014] In the power conversion device according to the first phase described above, preferably, the phase correction unit corrects the phase of the command value by the amount of the phase correction. With this configuration, errors in tracking control when the phase of the output current lags behind the command value can be easily suppressed.

[0015] In the power converter according to the first aspect described above, preferably, the tracking signal output unit includes a DC-type ACR that performs control to suppress the deviation between the correction command value and the output current on the d-axis and q-axis. With this configuration, tracking control can be performed on the d-axis and q-axis, which are relatively easy to control, thus preventing the control program of the power converter from becoming complicated. The d-axis represents the active component, and the q-axis represents the inactive component.

[0016] In the power converter according to the first aspect described above, preferably, the tracking signal output unit includes an AC-type ACR that performs control to suppress the deviation between the correction command value and the output current on the UVW axis. With this configuration, when the output current is AC, tracking control can be performed on the UVW axis without coordinate transformation of the detected output current, thereby reducing the time required to control the power converter. The UVW axis represents the components of each phase in a three-phase AC.

[0017] A control method for a power converter according to the second aspect of this invention is a control method for a power converter that converts input power and outputs it to an output target, comprising: a command value generation step of generating a command value of the output current to be output to the outside; a phase correction step of correcting the phase of the command value based on a phase correction amount calculated based on at least one of the output current and a transfer function generated based on a model of the output target; and a tracking signal output step of outputting a signal for controlling the output current so as to track a corrected command value, which is a command value whose phase has been corrected in the phase correction step.

[0018] The control method for a power converter according to the second aspect of this invention corrects the phase of the command value based on a phase correction amount calculated based on at least one of the output current and the transfer function generated based on the model of the output target, as described above. Here, the output current and the transfer function generated based on the model of the output target reflect the phase shift caused by the transfer characteristics of the output target. Therefore, by correcting the phase of the command value based on a phase correction amount calculated based on at least one of the output current and the transfer function generated based on the model of the output target, as described above, the phase of the command value can be corrected based on a phase correction amount that includes the phase shift caused by the transfer characteristics of the output target. As a result, it is possible to provide a control method for a power converter that can suppress errors in tracking control caused by the transfer characteristics of the output target. [Effects of the Invention]

[0019] According to the present invention, as described above, errors in tracking control caused by the transmission characteristics of the output target can be suppressed. [Brief explanation of the drawing]

[0020] [Figure 1] This is a block diagram showing the configuration of a power conversion device according to the first embodiment of the present invention. [Figure 2] This figure illustrates the delay between the output current and the command value according to the first embodiment of the present invention. [Figure 3] This is a block diagram illustrating the internal configuration of the tracking signal output unit according to the first embodiment of the present invention. [Figure 4] This flowchart shows the control process for the control method of a power conversion device according to the first embodiment of the present invention. [Figure 5] This is a block diagram showing the configuration of a power conversion device according to a second embodiment of the present invention. [Figure 6] This figure illustrates a method for calculating the sine and cosine of a phase correction amount based on an output current and a command value according to a second embodiment of the present invention. [Figure 7] This is a block diagram showing the configuration of a power conversion device according to a third embodiment of the present invention. [Figure 8] This is a Bode plot ((a): gain characteristics, (b): phase characteristics) illustrating a method for calculating a phase correction amount based on a loop transfer function according to a third embodiment of the present invention. [Figure 9] This is a block diagram showing the configuration of a power conversion device according to a fourth embodiment of the present invention. [Figure 10] This is a block diagram illustrating the internal configuration of the tracking signal output unit according to the fourth embodiment of the present invention. [Modes for carrying out the invention]

[0021] The following describes embodiments of the present invention based on the drawings.

[0022] [First Embodiment] The configuration of the power converter 100 according to the first embodiment will be described with reference to Figures 1 to 3.

[0023] (Configuration of power converter) As shown in Figure 1, the power converter 100 is configured to convert the DC power input from the DC power source 200 into AC power and supply (transmit) power to the AC system 250 via the reactor 210, reactor 220, capacitor 230, and resistor 240, etc. The DC power source 200 is, for example, a storage battery and a solar cell. The AC system 250 is an example of the "output target" and "power system" in the claims.

[0024] As shown in Figure 1, the power conversion device 100 comprises a power conversion unit 10 and a control unit 11.

[0025] The power conversion unit 10 is configured to convert the input DC power into AC power and output it to the AC system 250, which is the target of the output. The power conversion unit 10 includes a gate circuit 10a. The gate circuit 10a includes, for example, a switching element (not shown). The power conversion unit 10 is configured to control the AC power output from the power conversion unit 10 by controlling the switching operation of the switching element included in the gate circuit 10a by the control unit 11. Specifically, the AC power output from the power conversion unit 10 is controlled by the control unit 11 by controlling the gate signal F input to the gate terminal (not shown) of the switching element. By controlling the AC power output from the power conversion unit 10, it becomes possible to control the current, voltage, power factor, etc. in the AC system 250.

[0026] The control unit 11 is configured to control the power conversion performed by the power conversion unit 10. Functionally, the control unit 11 includes a command value generation unit 20, a phase detection unit 30, a phase correction unit 40, and a tracking signal output unit 50. In the control unit 11, the command value generation unit 20, the phase detection unit 30, the phase correction unit 40, and the tracking signal output unit 50 may be configured so that their respective functions are realized by software configuration, or they may be configured so that their respective functions are realized by a hardware circuit configuration that performs calculation processing. Alternatively, the control unit 11 may be configured so that their respective functions are realized by a combination of software and hardware.

[0027] The command value generation unit 20 generates a command value I for the output current that is output externally based on the system voltage Va in the AC system 250 and the output current Ia output from the power converter 100. * It is configured to generate a command value I * It is configured to generate the following. The output current Ia output from the power converter 100 is detected by a detector 260 consisting of a current sensor and output to the control unit 11 (power converter 100). The system voltage Va is detected by a detector 270 consisting of a voltage sensor and output to the control unit 11 (power converter 100). Command value I * This is the d-axis component I d * , and the q-axis component I q * Includes. Command value I * This is the command value for the output current output from the power conversion unit 10. Note that the system voltage Va is an example of "voltage in the power system" as defined in the claims.

[0028] The phase detection unit 30 is configured to detect the phase from the voltage. Specifically, the phase detection unit 30 detects the reference phase θ1 that serves as a reference during coordinate conversion from the system voltage Va. Then, the phase detection unit 30 outputs the detected reference phase θ1 to a phase correction unit 40 described later. The phase detection unit 30 is, for example, a phase detector such as a PLL (Phase Locked Loop).

[0029] The phase correction unit 40 corrects the phase of the command value I * and outputs it as a corrected command value I ** . Note that the command value I ** is the component of each of the U, V, and W axes, namely I U ** , I V ** and I W ** . The phase correction unit 40 includes a reference phase correction unit 41 and a coordinate conversion unit 42. The reference phase correction unit 41 corrects the reference phase θ1 output from the phase detection unit 30 by advancing it by the phase correction amount δ and outputs a corrected phase θ2. The arithmetic processing for advancing the reference phase θ1 by the phase correction amount δ is performed by the following formula (1).

Equation

number

[0030] In the first embodiment, the reference phase correction unit 41 (phase correction unit 40) is configured to calculate the phase correction amount δ at predetermined control cycles and update the phase correction amount δ.

[0031] The coordinate transformation unit 42 is configured to transform the coordinates of the input voltage or current from the d-axis and q-axis to the UVW-axis. Specifically, the coordinate transformation unit 42 in Figure 1 is configured to transform the command value I * Then, using the correction phase θ2, the coordinates are transformed from the d-axis and q-axis to the UVW-axis to obtain the correction command value I. ** It is configured to perform calculation processing to output the following. The calculation processing by the coordinate transformation unit 42 is performed by the following equation (3).

number

[0032] The tracking signal output unit 50 outputs a corrected command value I whose phase has been corrected by the phase correction unit 40. ** The system is configured to output a gate signal F for controlling the output current Ia in accordance with the current. As shown in Figure 3, the tracking signal output unit 50 includes a current control unit 51 and a tracking signal conversion unit 52. The gate signal F is an example of the "signal for controlling the output current" in the claims.

[0033] As shown in Figure 3, the current control unit 51 is configured to function as an ACR (Auto Current Regulator) that suppresses the deviation between the command value and the controlled amount of the current on the UVW axis and outputs a voltage. Note that when the frequency is constant, the current on the UVW axis is alternating current. In other words, the current control unit 51 corrects the command value I ** This is an AC-type ACR that performs control to suppress the deviation between the current and the output current Ia on the UVW axis. The current control unit 51 controls the correction command value I on the UVW axis. ** Control is performed to suppress the deviation D1 between the output current Ia and the current, and a tracking voltage V1 is output. Correction command value I ** Controls to suppress the deviation D1 between the current and the output current Ia include, for example, PI control, which performs proportional control (P control) and integral control (I control) with respect to the deviation, and PR control, which performs proportional control (P control) and resonant control (R control) with respect to the deviation.

[0034] The tracking signal output unit 50 is configured to add the tracking voltage V1 output from the current control unit 51 and the system voltage Va and input the command voltage Vb to the tracking signal conversion unit 52. The tracking signal conversion unit 52 is configured to convert the input voltage into a gate signal F for operating the gate circuit 10a (see Figure 1) by PWM (Pulse Width Modulation) control. Specifically, as shown in Figures 1 and 3, the tracking signal conversion unit 52 converts the command voltage Vb into a rectangular pulse signal (PWM wave) according to a predetermined carrier frequency and outputs the converted pulse signal as a gate signal F to the gate circuit 10a of the power conversion unit 10. The gate circuit 10a is configured to perform ON / OFF operations of a switching element according to the input gate signal F.

[0035] (Control method for power converters) Next, with reference to Figure 4, the control process of the control method for the power converter 100 of the first embodiment will be described. Note that the control processes in steps S1 to S3 in Figure 4 are executed by the control unit 11. Furthermore, the control processes in steps S1 to S3 are executed repeatedly at predetermined control cycles.

[0036] As shown in Figure 4, in step S1, the command value I * The following is generated. Specifically, in the first embodiment, the command value generation unit 20 generates a command value I of the output current that is output externally based on the system voltage Va in the AC system 250 and the output current Ia output from the power converter 100. * The following is generated. Step S1 is an example of the "command value generation step" in the claims. In the first embodiment, in step S1, the command value I of the output current Ia that is output to the outside is generated. * This is generated.

[0037] Next, in step S2, the command value I * The phase is corrected. Specifically, in the first embodiment, the phase correction unit 40 corrects the command value I generated by the command value generation unit 20. * The phase is corrected so that it advances by a phase correction amount δ. The phase correction unit 40 sets the phase correction amount δ to the command value I of the output current Ia, which is the control variable. * The delay τ relative to is detected, and the detected delay τ is converted into phase to calculate the value. Step S2 is an example of the "phase correction step" in the claims. In the first embodiment, in step S2, the command value I * The phase is corrected based on a phase correction amount δ calculated based on at least one of the output current Ia and the loop transfer function generated based on the model of the AC system 250 to be output. The loop transfer function generated based on the model of the AC system 250 will be described later.

[0038] Next, in step S3, a gate signal F for controlling the output current Ia is output. Specifically, in the first embodiment, the tracking signal output unit 50 outputs a corrected command value I whose phase has been corrected by the phase correction unit 40.** A gate signal F is output to control the output current Ia in accordance with this. Step S3 is an example of the "following signal output step" in the claims. In the first embodiment, in step S3, the correction command value I, whose phase has been corrected in step S2, is output. ** In accordance with this, a gate signal F is output to control the output current Ia.

[0039] (Effects of the first embodiment) Next, the effects of the first embodiment will be described.

[0040] In the first embodiment, as described above, the phase correction unit 40 sets a command value I based on the phase correction amount δ calculated based on the output current Ia. * The phase is corrected. Here, the output current Ia reflects the phase shift caused by the impedance characteristics, which are the transfer characteristics of the output device. Therefore, the command value I is calculated based on the phase correction amount δ calculated based on the output current Ia as described above. * By correcting the phase, the command value I is determined based on the phase correction amount δ, which includes the phase shift caused by the impedance characteristics, which are the transfer characteristics of the output target. * The phase can be corrected. As a result, errors in tracking control caused by the transfer characteristics of the output target can be suppressed.

[0041] Furthermore, in the first embodiment, as described above, the output target includes the AC system 250, and the command value generation unit 20 generates a command value I based on the system voltage Va and output current Ia in the AC system 250. * This generates a command value I for controlling the power factor in the AC system 250 to a desired value. This allows the power factor in the AC system 250 to be calculated based on the system voltage Va in the AC system 250 and the output current Ia of the power converter 100. * It can be easily generated.

[0042] Furthermore, in the first embodiment, as described above, the phase correction unit 40 controls the command value I of the output current Ia. *The phase correction amount δ is calculated based on the delay τ. This allows for accurate correction of the phase due to the actual tracking control error.

[0043] Furthermore, in the first embodiment, as described above, the phase correction unit 40 is configured to update the phase correction amount δ at predetermined intervals. This ensures that even when the error of the tracking control changes over time, the command value I of the output current Ia remains constant. * The phase correction amount δ can be updated in real time in response to the temporal change in the delay τ relative to the given value.

[0044] Furthermore, in the first embodiment, as described above, the phase correction unit 40 adjusts the command value I by the amount of the phase correction amount δ. * The phase is corrected to advance. This corrects the command value I * This makes it easy to suppress errors in tracking control when the phase of the output current Ia lags behind the other parameters.

[0045] Furthermore, in the first embodiment, as described above, the tracking signal output unit 50 outputs a correction command value I ** This includes an AC-type ACR that performs control to suppress the deviation between the detected output current Ia and the UVW axis. As a result, when the output current Ia is AC, tracking control can be performed on the UVW axis without coordinate transformation of the detected output current Ia, thereby reducing the time required to control the power converter 100.

[0046] [Second Embodiment] Next, the configuration of the power converter 300 according to the second embodiment will be described with reference to Figures 5 and 6. In the second embodiment, the phase correction unit 40 in the first embodiment is changed to a phase correction unit 340. The other configurations of the second embodiment are the same as those of the first embodiment. Components the same as those of the first embodiment are denoted by the same reference numerals and their description is omitted. The control processing of the control method of the power converter 300 in the second embodiment is the same as that of the first embodiment.

[0047] In the second embodiment, the output current Ia and the command value I *Based on the d-axis and q-axis components, the sine and cosine of the phase correction amount δ are calculated, and based on the sine and cosine of the phase correction amount δ, the sine and cosine of the corrected phase θ2 are calculated. Then, based on the calculated sine and cosine of the corrected phase θ2, the command value I is calculated. * Correct the phase.

[0048] (Configuration of the power converter according to the second embodiment) As shown in Figure 5, the power converter 300 according to the second embodiment comprises a power conversion unit 10 and a control unit 311. The control unit 311 functionally includes a command value generation unit 20, a phase detection unit 30, a phase correction unit 340, and a tracking signal output unit 50. The phase correction unit 340 includes a coordinate transformation unit 341, a reference phase correction unit 342, and a coordinate transformation unit 42, and, similar to the phase correction unit 40 according to the first embodiment (see Figure 1), it generates a command value I generated by the command value generation unit 20. * The phase is corrected, and the correction command value I ** It is configured to output as follows. The coordinate transformation unit 341 is configured to transform the coordinates of the input voltage or current from the UVW axis to the d axis and q axis. Specifically, the coordinate transformation unit 341 in Figure 5 is configured to perform calculation processing to transform the output current Ia from the UVW axis to the d axis and q axis using the reference phase θ1 and output the output current I. Note that the output current I is the d-axis component I d , and the I of the q-axis component q It includes the following. The calculation processing by the coordinate transformation unit 341 is performed by the following equation (4).

number

[0049] The reference phase correction unit 342 controls the command value I *The system is configured to output the sine and cosine of the correction phase θ2 based on the output current I output from the coordinate transformation unit 341. Specifically, as shown in Figure 6, the reference phase correction unit 342 is configured to output the d-axis component and the q-axis component of the output current I, which are I2, based on the output current I. d and I q And, command value I * And, command value I * I, which is the d-axis component and q-axis component of d * and I q * Based on this, the system is configured to calculate the sine and cosine of the phase correction amount δ using equations (5) and (6) below.

number

number

number

number

[0050] As described above, in the second embodiment, the phase correction unit 340 controls the output current Ia and the command value I * Based on this, the command value I is calculated by calculating the phase correction amount δ. * The phase is corrected. Specifically, in the second embodiment, the phase correction unit 340 corrects the output current Ia and the command value I * Based on this, the command value I is calculated by determining the sine and cosine of the phase correction amount δ. * The phase is being corrected.

[0051] In the second embodiment, the phase correction unit 340 is configured to calculate the phase correction amount δ (sine and cosine) at predetermined control cycles and update the phase correction amount δ (sine and cosine).

[0052] (Effects of the second embodiment) Next, the effects of the second embodiment will be described.

[0053] In the second embodiment, as described above, the phase correction unit 340 controls the output current Ia and the command value I * Based on this, the command value I is calculated by determining the sine and cosine of the phase correction amount δ. * The phase is corrected. This allows the sine and cosine of the calculated phase correction amount δ to be set to the command value I. * By directly substituting into the calculation formula for correcting the phase, the command value I * The phase can be easily corrected. Furthermore, the other effects of the second embodiment are the same as those of the first embodiment.

[0054] [Third Embodiment] Next, the configuration of the power converter 400 according to the third embodiment will be described with reference to Figures 7 and 8. In the third embodiment, the phase correction unit 40 in the first embodiment is changed to a phase correction unit 440. The other configurations of the third embodiment are the same as those of the first embodiment. Components the same as those of the first embodiment are denoted by the same reference numerals and their description is omitted. The control processing of the control method for the power converter 400 in the third embodiment is the same as that of the first embodiment.

[0055] In the third embodiment, the command value I is calculated based on a model of the AC system 250 that is the output target of the power converter 400, and a loop transfer function generated based on the model of the power converter 400. * The phase is being corrected.

[0056] (Configuration of the power converter according to the third embodiment) As shown in Figure 7, the power converter 400 according to the third embodiment comprises a power conversion unit 10 and a control unit 411. The control unit 411 functionally includes a command value generation unit 20, a phase detection unit 30, a phase correction unit 440, and a tracking signal output unit 50. The phase correction unit 440 includes a reference phase correction unit 441 and a coordinate transformation unit 42, and, similar to the phase correction unit 40 according to the first embodiment (see Figure 1), generates a command value I generated by the command value generation unit 20. * The phase is corrected, and the correction command value I ** It is configured to output as follows. The reference phase correction unit 441 has in advance a model of the AC system 250 that is the output target of the power converter 400, and a Bode plot of the loop transfer function generated based on the model of the power converter 400, as shown in Figures 8(a) and 8(b). The reference phase correction unit 441 is configured to acquire the gain G at the operating frequency FC based on the gain characteristic LG of the loop transfer function, as shown in Figure 8(a). The operating frequency FC is, for example, the frequency of the AC system 250 (system frequency). The reference phase correction unit 441 is also configured to acquire the amount of deviation δa between the initial phase P1 and the phase P2 corresponding to the operating frequency FC, as shown in Figure 8(b), based on the phase characteristic LP of the loop transfer function. The initial phase is the phase when the frequency is zero. For example, the initial phase P1 in the third embodiment is 0 [deg]. Here, the amount of deviation δa is caused by the impedance characteristics of the AC system 250 and the power converter 400. The reference phase correction unit 441 is configured to calculate the phase correction amount δ based on the calculated gain G and the shift amount δa using the following equation (9).

number

[0057] (Effects of the third embodiment) Next, the effects of the third embodiment will be described.

[0058] In the third embodiment, as described above, the phase correction unit 440 calculates a command value I based on the phase correction amount δ calculated based on the transfer function generated based on the model of the AC system 250 that is the target of output. * The phase is corrected. Here, the transfer function generated based on the model of the AC system 250 to be output reflects the phase shift caused by the transfer characteristics of the AC system 250 to be output. Therefore, the command value I is calculated based on the phase correction amount δ calculated based on the transfer function generated based on the model of the AC system 250 to be output as described above. * By correcting the phase, the command value I is determined based on the phase correction amount δ, which includes the phase shift caused by the transmission characteristics of the AC system 250 that is the target of the output. * The phase can be corrected. As a result, errors in tracking control caused by the transmission characteristics of the AC system 250, which is the output target, can be suppressed.

[0059] Furthermore, in the third embodiment, as described above, the transfer function includes a loop transfer function, and the phase correction unit 440 calculates the phase correction amount δ based on the amount of shift δa between the initial phase P1 and the phase P2 corresponding to the operating frequency FC in the loop transfer function. This makes it possible to calculate the phase correction amount δ in advance by generating the loop transfer function in advance based on the model of the AC system 250 that is the target of the output. Other effects of the third embodiment are the same as those of the first embodiment.

[0060] [Fourth Embodiment] Next, the configuration of the power converter 500 according to the fourth embodiment will be described with reference to Figures 9 and 10. In the fourth embodiment, the phase correction unit 40 and the tracking signal output unit 50 in the first embodiment are changed to a phase correction unit 540, a tracking signal output unit 550, and a coordinate transformation unit 341. The other configurations of the fourth embodiment are the same as those of the first embodiment. Components the same as those in the first embodiment are denoted by the same reference numerals and their description is omitted. The control processing of the control method for the power converter 500 in the fourth embodiment is the same as that of the first embodiment.

[0061] In the fourth embodiment, the correction command value I ** Unlike the first embodiment, which includes an AC-type ACR that performs control to suppress the deviation between the output current Ia and the correction command value I ** It is configured to include a DC-type ACR that performs control to suppress deviations between the output current Ia and the d-axis and q-axis.

[0062] (Configuration of the power converter according to the fourth embodiment) As shown in Figure 9, the power converter 500 according to the fourth embodiment comprises a power conversion unit 10 and a control unit 511. The control unit 511 functionally includes a command value generation unit 20, a phase detection unit 30, a coordinate transformation unit 341, a phase correction unit 540, and a tracking signal output unit 550.

[0063] The coordinate conversion unit 341 is configured to perform an arithmetic process of coordinate-converting the output current Ia from the UVW axes to the d-axis and q-axis using the reference phase θ1 and outputting the output current I, in the same manner as the coordinate conversion unit 341 (see FIG. 5) in the second embodiment. The output current I output from the coordinate conversion unit 341 is input to the tracking signal output unit 550.

[0064] The phase correction unit 540 corrects the phase of the command value I generated by the command value generation unit 20 and outputs it as the corrected command value I on the d-axis and q-axis. Note that the corrected command value I includes I of the d-axis component and I of the q-axis component. Specifically, the phase correction unit 540 corrects the phase of the command value I on the d-axis and q-axis by advancing it by the phase correction amount δ. The arithmetic process of advancing the phase of the command value I by the phase correction amount δ is performed by the following equation (10). * on the d-axis and q-axis as ** Note that the corrected command value I ** is I of the d-axis component d ** and I of the q-axis component q ** Specifically, the phase correction unit 540 corrects the phase of the command value I on the d-axis and q-axis by advancing it by the phase correction amount δ. * The arithmetic process of advancing the phase of the command value I by the phase correction amount δ is performed by the following equation (10). * is performed by the following equation (10).

Equation

[0065] The tracking signal output unit 550 is configured to output a gate signal F for controlling the output current Ia so as to track the corrected command value I whose phase has been corrected by the phase correction unit 5.AS shown in FIG. 10, the tracking signal output unit 550 includes a current control unit 551, a coordinate conversion unit 42, and a tracking signal conversion unit 52. ** Note that in the fourth embodiment, the phase correction unit 540 is configured to calculate the phase correction amount δ every predetermined control cycle and update the phase correction amount δ.

[0066] As shown in FIG. 10, the current control unit 551 performs control to suppress the deviation between the command value and the control amount of the current on the d-axis and q-axis, and is configured to function as an ACR (Auto Current Regulator) that outputs a voltage. When the frequency is constant, the current becomes direct current on the d-axis and q-axis. That is, the current control unit 551 ** is a DC type ACR that performs control to suppress the deviation on the d-axis and q-axis between the correction command value I ** and the output current Ia(I). The current control unit 551 performs control to suppress the deviation D2 between the correction command value I ** and the output current I on the d-axis and q-axis, and outputs a voltage V2. The control for suppressing the deviation D2 between the correction command value I

[0067] The coordinate conversion unit 42 is configured to perform coordinate conversion of the input voltage or current coordinates from the d-axis and q-axis to the UVW axis, similar to the coordinate conversion unit 42 (see FIG. 1) of the first embodiment. Specifically, the coordinate conversion unit 42 in FIG. 10 is configured to perform arithmetic processing for coordinate conversion of the voltage V2 from the d-axis and q-axis to the UVW axis using the reference phase θ1 and output the following voltage V1. The arithmetic processing by the coordinate conversion unit 42 in FIG. 10 is performed according to the following formula (11).

Equation

[0068] The tracking signal output unit 550 is configured to add the tracking voltage V1 output from the coordinate transformation unit 42 and the system voltage Va to input the command voltage Vb to the tracking signal conversion unit 52. The tracking signal conversion unit 52 is configured to convert the input voltage into a gate signal F for operating the gate circuit 10a (see Figure 9) by PWM (Pulse Width Modulation) control. Specifically, as shown in Figures 9 and 10, the tracking signal conversion unit 52 converts the command voltage Vb into a rectangular pulse signal (PWM wave) according to a predetermined carrier frequency and outputs the converted pulse signal as a gate signal F to the gate circuit 10a of the power conversion unit 10. The gate circuit 10a is configured to perform ON / OFF operations of a switching element according to the input gate signal F.

[0069] (Effects of the fourth embodiment) Next, the effects of the fourth embodiment will be described.

[0070] In the fourth embodiment, as described above, the tracking signal output unit 450 outputs a correction command value I ** This includes a DC-type ACR that performs control to suppress the deviation D2 between the output current I(Ia) and the power converter on the d-axis and q-axis. This allows tracking control to be performed on the d-axis and q-axis, which are relatively easy to control, thus preventing the control program of the power converter from becoming complicated. The other effects of the fourth embodiment are the same as those of the first embodiment.

[0071] According to the first to fourth embodiments, in the power conversion device of the present invention, the phase correction unit calculates a command value I based on a phase correction amount δ calculated based on at least one of the output current Ia and a loop transfer function generated based on a model of the AC system 250. * The phase is being corrected.

[0072] [Differentiation] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than by the description of the embodiments above, and further includes all modifications (exceptions) within the meaning and scope equivalent to the claims.

[0073] In the first to fourth embodiments described above, an example was shown in which an AC system 250 (power system) was applied as the output target of the power converter, but the present invention is not limited thereto. For example, in addition to the AC system 250, a reactor 210, a reactor 220, a capacitor 230, and a resistor 240 may be applied as the output target of the power converter. Alternatively, a load such as a motor may be applied as the output target of the power converter. When an AC motor is applied as the output target of the power converter, the operating frequency FC should be the rotation frequency of the AC motor. In any case, in the third embodiment, a loop transfer function is generated based on the applied output target.

[0074] Furthermore, while the first to fourth embodiments described above show an example where the power conversion unit 10 converts DC power to AC power, the present invention is not limited to this. For example, the power conversion unit 10 may also convert AC power to DC power.

[0075] Furthermore, in the first to fourth embodiments described above, the power conversion unit 10 is shown to supply (transmit) power from a DC power source 200 to an AC system 250, but the present invention is not limited to this. For example, the power conversion unit 10 may be configured to receive power from the AC system 250, or it may be configured to both transmit and receive power.

[0076] Furthermore, in the first to fourth embodiments described above, the command value generation unit 20 generates a command value I based on the system voltage Va and the output current Ia. * An example has been shown of a configuration to generate a command value I * You may generate this.

[0077] Furthermore, in the first, second, and fourth embodiments described above, the phase correction units 40, 340, and 540 are configured to calculate a phase correction amount δ at predetermined control cycles and update the phase correction amount δ, but the present invention is not limited thereto. For example, the phase correction amount δ calculated at the start of control may be used continuously until the end of control. Also, in the third embodiment, the phase correction amount δ may be calculated at predetermined control cycles and updated.

[0078] Furthermore, in the third embodiment described above, the phase correction unit 440 calculates a command value I based on the phase correction amount δ calculated based on the loop transfer function generated based on the model to be output. * An example of phase correction has been shown, but the present invention is not limited to this. For example, the phase correction unit 440 calculates a command value I based on the phase correction amount δ calculated based on the open-loop transfer function generated based on the model of the output target. * The phase may be corrected, or the command value I may be calculated based on the phase correction amount δ calculated based on the closed-loop transfer function generated based on the model to be output. * The phase may be corrected.

[0079] Furthermore, in the first to fourth embodiments described above, the command value I is equal to the phase correction amount δ. * An example of correcting the phase to advance it has been shown, but the present invention is not limited to this. For example, the command value I is corrected by the amount of the phase correction δ. * The phase may be corrected to delay it.

[0080] Furthermore, while the first to third embodiments described above show examples of calculating the phase correction amount δ by individually using different single calculation methods, the present invention is not limited thereto. For example, the phase correction amount δ may be calculated by combining each calculation method, such as calculating the phase correction amount δ based on the loop transfer function before control and then calculating and updating the phase correction amount δ based on the output current Ia during control. Alternatively, multiple phase correction amounts may be calculated using a single calculation method, and their average value may be calculated as the phase correction amount δ.

[0081] Furthermore, in the fourth embodiment described above, the phase correction amount δ is the command value I of the output current Ia, which is a controlled quantity, according to equation (2) above, similar to the first embodiment. * An example has been shown in which a delay τ relative to the current is detected and the detected delay τ is converted to phase to calculate the current, but the present invention is not limited to this. For example, similar to the second embodiment, the output current I and the d-axis and q-axis components of the output current I are used. d and I q And, command value I * And, command value I * I, which is the d-axis and q-axis component of d * and I q * Based on this, the phase correction amount δ may be calculated by calculating the sine and cosine of the phase correction amount δ using equations (5) and (6) above. [Explanation of Symbols]

[0082] 10 Power conversion unit 11, 311, 411, 511 Control Unit 20 Command Value Generation Unit 40, 340, 440, 540 Phase correction section 50, 550 Tracking signal output section 100, 300, 400, 500 Power Converters 250 AC systems (output target, power systems) Ia Output current Va System voltage (voltage in the power system) I * Command value I ** Correction command value τ delay (delay in output current relative to command value) F gate signal (a signal used to control the output current) δ Phase correction amount δa is the amount of phase shift (the amount of phase shift from the initial phase to the operating frequency in the loop transfer function). FC operating frequency P1 Initial Phase P2 Phase (Phase corresponding to operating frequency)

Claims

1. A power conversion unit that converts the input power and outputs it to the output target, The system comprises a control unit that controls the power conversion performed by the power conversion unit, The control unit, A command value generation unit that generates a command value for the output current to be output to the outside, A phase correction unit that corrects the phase of the command value generated by the command value generation unit, It includes a tracking signal output unit that outputs a signal for controlling the output current so as to follow the corrected command value, which is the command value whose phase has been corrected by the phase correction unit, The phase correction unit corrects the phase of the command value based on a phase correction amount calculated based on at least one of the output current and a transfer function generated based on the model of the output target, in a power conversion device.

2. The output target includes the power system, The power conversion device according to claim 1, wherein the command value generation unit generates the command value based on the voltage in the power system and the output current.

3. The power conversion device according to claim 1, wherein the phase correction unit calculates the phase correction amount based on the delay of the output current with respect to the command value.

4. The power conversion device according to claim 3, wherein the phase correction unit is configured to update the phase correction amount at predetermined intervals.

5. The power conversion device according to claim 1, wherein the phase correction unit corrects the phase of the command value by calculating the sine and cosine of the phase correction amount based on the output current and the command value.

6. The transfer function includes a loop transfer function, The power converter according to claim 1, wherein the phase correction unit calculates the phase correction amount based on the amount of deviation of the phase corresponding to the operating frequency in the loop transfer function from the initial phase.

7. The power conversion device according to claim 1, wherein the phase correction unit corrects the phase of the command value by the amount of the phase correction.

8. The power conversion device according to claim 1, wherein the tracking signal output unit includes a DC type ACR that performs control to suppress deviations between the correction command value and the output current on the d axis and q axis.

9. The power conversion device according to claim 1, wherein the tracking signal output unit includes an AC type ACR that performs control to suppress the deviation between the correction command value and the output current on the UVW axis.

10. A control method for a power converter that converts input power and outputs it to an output target, A command value generation step that generates a command value for the output current to be output to the outside, A phase correction step in which the phase of the command value is corrected based on a phase correction amount calculated based on at least one of the output current and the transfer function generated based on the model of the output target, A control method for a power converter, comprising: a tracking signal output step which outputs a signal for controlling the output current so as to follow the correction command value, which is the command value whose phase has been corrected in the phase correction step.

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