JP6264913B2 - Power converter control device and power conversion system - Google Patents

Description

  The present invention relates to a power converter, and more particularly to a technique for reducing the number of switching times of a switching element included in the power converter.

  A power conversion device is used as a device that outputs an alternating voltage. The power conversion device converts the input DC voltage into an AC voltage and outputs the AC voltage. Such a power converter is controlled based on a comparison between a carrier and a voltage command, for example. The voltage command is a command value for an AC voltage (hereinafter also referred to as an output voltage) output from the power converter.

  FIG. 4 shows an example of the voltage command V * and the carrier C1. Here, the switching signal S is activated when the voltage command V * is equal to or higher than the carrier C1. In the example of FIG. 4, since the voltage command V * becomes equal to or higher than the carrier C1 in the period t21, the switching signal S is activated in the period t21. Since the voltage command V * is smaller than the carrier C1 at the beginning of the period t22 following the period t21, the switching signal S becomes inactive, and the voltage command V * becomes equal to or higher than the carrier C1 during the period t22. The switching signal S becomes active again. Immediately after the period t22, since the voltage command V * is smaller than the carrier C1, the switching signal S is deactivated again.

  Patent Documents 1 to 3 are listed as techniques related to the present invention.

JP2012-110088A JP 2012-110087 A JP 2012-165515 A

  Frequent switching of the switching signal between active / inactive is undesirable because it increases the number of switching times, which in turn increases switching loss.

  Then, an object of this invention is to provide the control apparatus which suppresses the frequency | count of switching of a power converter device.

  A first aspect of a control device for a power conversion device according to the present invention includes a switching element connected in series between a pair of input terminals to which a DC voltage is applied, and converts the DC voltage into an AC voltage. A power converter (1) that controls the voltage command generator (31) that updates the voltage command (V *) for the AC voltage and a triangular wave carrier (C1) that is variable. A carrier generation unit (32) that generates a carrier cycle, and a switching signal generation unit (33) that generates a switching signal (S) based on the comparison between the voltage command and the carrier, and applies the switching signal to the switching element. The voltage command is updated from a first value (V1) greater than or equal to the peak value (Vc1) of the carrier to an intermediate value between the peak value and the bottom value (Vc2) of the carrier. After timing (t2), first the carrier When it is predicted at the first prediction timing (t1) before the first update timing that the rate of change with respect to time of the carrier is negative at the time when the intermediate value is taken, (i) the carrier generation The change of the carrier at a time when the carrier first takes the intermediate value after the first update timing by changing the carrier period in a part of the period after the first prediction timing. (Ii) the voltage command generation unit is configured to maintain the magnitude relationship between the voltage command and the carrier in a period in which the carrier cycle is changed. After the second update timing (t4) when the voltage command is determined and / or the voltage command is updated from the second value (V2) below the bottom value to the intermediate value, (Iii) when the carrier predicts that the rate of change of the carrier is positive at the second prediction timing (t3) prior to the second update timing The change of the carrier at a time when the carrier first takes the intermediate value after the second update timing by changing the carrier period in a part of the period after the second prediction timing. (Iv) the voltage command generator generates the carrier so that the rate is negative, and the voltage command generator is configured to maintain the magnitude relationship between the voltage command and the carrier in a period in which the carrier cycle is changed. Determine the voltage command.

  A second aspect of the control device for the power conversion device according to the present invention is the control device for the power conversion device according to the first aspect, wherein the carrier generation unit (32) includes the carrier in the partial period. Reduce the period.

  A third aspect of the power conversion device according to the present invention is the power conversion device according to the second aspect, wherein the voltage command takes a constant value every control cycle that is an integral multiple of a half cycle of the carrier, The part of the carrier that is subject to change of the carrier period is only one of a mountain-shaped part or a valley-shaped part with the carrier period as a unit, and the carrier generation unit (32) The carrier period is changed to half.

  A fourth aspect of the control device for the power conversion device according to the present invention is the control device for the power conversion device according to the first aspect, in which the carrier generation unit (32) includes the carrier in the partial period. Increase the period.

  A fifth aspect of the control device for the power conversion device according to the present invention is the control device for the power conversion device according to any one of the first to fourth aspects, wherein the carrier generation unit (32) In some periods, the carrier period is changed by changing the amplitude of the carrier (C1).

  The 6th aspect of the control apparatus of the power converter device concerning this invention is a control apparatus of the power converter device concerning any one of the 1st, 2nd, 4th, 5th aspect, Comprising: Of the said carriers The part to be changed of the carrier period is only one of a mountain-shaped part or a valley-shaped part with the carrier period as a unit.

  An aspect of the power conversion system according to the present invention includes the control device (3) for the power conversion device according to any one of the first to sixth aspects, and the power conversion device (1).

  According to the first and fourth aspects of the control device of the power conversion device and the power conversion system according to the present invention, the carrier and voltage command before and after the first update timing and / or before and after the second update timing. Can maintain a large and small relationship. Thereby, the frequency | count that switching of activation / inactivation of a switching signal can be reduced, and, thereby, the frequency | count of switching in a power converter device can be reduced.

  Moreover, this switching signal is generated by changing the carrier period. For example, both the first carrier that increases with the passage of time and the second carrier that decreases with the passage of time are generated, the first carrier is selected immediately after the first update timing, and immediately after the second update timing. It is not necessary to generate a plurality of carriers as compared with the case of selecting the second carrier. Therefore, the configuration of the carrier generation unit can be simplified.

  According to the 2nd aspect of the power converter device concerning this invention, since a carrier period is reduced, even if it estimates with the 1st prediction timing nearer the 1st update timing, the change of a carrier period can be made in time. . If the voltage command is changed and the first update timing is advanced within the time from the first prediction timing to the first update timing, a situation occurs in which the change of the carrier cycle is not in time. If this time can be shortened, the possibility of the situation occurring can be reduced. The same applies to the second update timing and the first prediction timing.

  According to the 3rd aspect of the control apparatus of the power converter device concerning this invention, it contributes to reduction of a calculation load.

  According to the 5th aspect of the control apparatus of the power converter device concerning this invention, the change of a carrier period is easy compared with the case where the change rate with respect to the time of a carrier is changed and a carrier period is changed.

  According to the 6th aspect of the control apparatus of the power converter device concerning this invention, compared with the case where the carrier frequency of several peak-shaped part or valley-shaped part is changed, the 1st prediction timing nearer to the 1st update timing Even if the prediction is performed at the second prediction timing closer to the second update timing, the carrier cycle can be changed in time.

1 is a diagram illustrating a conceptual configuration of a power conversion system. It is a figure which shows an example of a voltage command. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command, a carrier, and an output voltage. It is a figure which shows an example of a voltage command. It is a figure which shows an example of a voltage command.

<1. Overall configuration>
As shown in FIG. 1, the power conversion system includes a power conversion device 1 and a control device 3. The power converter 1 is connected to input terminals P1, P2 and output terminals Pu, Pv, Pw. A DC voltage is applied to the input terminals P1 and P2. Here, the potential applied to the input terminal P2 is lower than the potential applied to the input terminal P1.

  In the illustration of FIG. 1, the power converter device 1 is connected to three output terminals Pu, Pv, and Pw. That is, a three-phase power converter 1 that outputs a three-phase AC voltage is shown in FIG. However, the power conversion device 1 is not limited to three phases, and may be a single phase, or may be three or more phases. Below, the case where the power converter device 1 is a three-phase is taken and demonstrated as an example.

  The power converter 1 converts a DC voltage into an AC voltage, and outputs this AC voltage to the output terminals Pu, Pv, Pw. As an example of a more detailed structure, the power conversion device 1 is a voltage source inverter, and includes switching elements S1 to S6 and diodes D1 to D6. The switching elements S1 to S6 are, for example, insulated gate bipolar transistors or field effect transistors. Each of the switching elements S1 to S3 is provided between each of the output terminals Pu, Pv, and Pw and the input terminal P1. Below, each switching element S1-S3 is also called an upper switching element. Diodes D1-D3 are connected in parallel with switching elements S1-S3, respectively. The forward direction of the diodes D1 to D3 is a direction from the input terminal P2 toward the input terminal P1. Each of the switching elements S4 to S6 is provided between each of the output terminals Pu, Pv, Pw and the input terminal P2. Hereinafter, the switching elements S4 to S6 are also referred to as lower switching elements. Diodes D4 to D6 are connected in parallel with switching elements S4 to S6, respectively. The forward direction of the diodes D4 to D6 is a direction from the input terminal P2 toward the input terminal P1.

  The power conversion device 1 is controlled by the control device 3 using a PWM (pulse width modulation) method. Switching signals are given to the switching elements S1 to S6 from the control device 3, respectively. The switching elements S1 to S6 are turned on by the switching signal. When the control device 3 gives switching signals to the switching elements S1 to S6 at appropriate timing, the power conversion device 1 converts the DC voltage into an AC voltage. The power conversion device 1 can output an AC voltage having an arbitrary frequency / amplitude based on the switching signal, for example, a sine wave AC voltage, an AC voltage (overmodulation) in which the upper limit and the lower limit of the sine wave are limited, Alternatively, an alternating voltage having one pulse in one cycle can be output. In this embodiment, a control technique for outputting an alternating voltage having one pulse will be described.

  Note that, under the control of the control device 3, the switching elements S1 and S4 are exclusively connected to each other, the switching elements S2 and S5 are exclusively connected to each other, and the switching elements S3 and S6 are exclusively connected to each other. This is to prevent the input terminals P1 and P2 from being short-circuited and a large current from flowing through the switching element.

  The power converter 1 can drive the load 2, for example. The load 2 is connected to the output terminals Pu, Pv, Pw. The load 2 is, for example, a motor, and rotates according to the AC voltage applied by the power conversion device 1.

<2. Control unit>
The control device 3 includes a voltage command generator 31, a carrier generator 32, and a switching signal generator 33. First, each of these elements will be outlined.

  The voltage command generation unit 31 generates a voltage command V * for the AC voltage output from the power conversion device 1, and outputs this to the switching signal generation unit 33. In the illustration of FIG. 1, since the power converter device 1 outputs a three-phase AC voltage, the voltage command V * includes three phase voltage commands Vu *, Vv *, and Vw *.

  The carrier generation unit 32 generates a triangular wave (for example, isosceles triangular wave) carrier C <b> 1 with a variable carrier period, and supplies this to the switching signal generation unit 33.

  The switching signal generator 33 generates a switching signal to the switching elements S1 to S6 based on the comparison between the voltage command V * from the voltage command generator 31 and the carrier C1 from the carrier generator 32.

  Here, the control device 3 includes a microcomputer and a storage device. The microcomputer executes each processing step (in other words, a procedure) described in the program. The storage device is composed of one or more of various storage devices such as a ROM (Read Only Memory), a RAM (Random Access Memory), a rewritable nonvolatile memory (EPROM (Erasable Programmable ROM), etc.), and a hard disk device, for example. Is possible. The storage device stores various information, data, and the like, stores a program executed by the microcomputer, and provides a work area for executing the program. It can be understood that the microcomputer functions as various means corresponding to each processing step described in the program, or can realize that various functions corresponding to each processing step are realized. Further, the control device 3 is not limited to this, and various procedures executed by the control device 3 or various means or various functions to be realized may be realized by hardware.

  An example of the voltage command V * will be described in detail with reference to FIG. The voltage command V * has a constant value for each predetermined period (hereinafter referred to as a control period). Therefore, the voltage command V * changes stepwise in FIG. In the example of FIG. 2, periods t10 to t18 are shown as periods (hereinafter referred to as “control periods”) in which each has a control cycle and the voltage command V * is constant in each. In the example of FIG. 2, the voltage command V * rises from a value V2 (for example, 0) at the end of the period t10 (starting of the period t11), takes an intermediate value, and rises at the end of the period t11 (starting of the period t12). The value V1 (> intermediate value> V2) is taken. Hereinafter, the values V1 and V2 are also referred to as a first value V1 and a second value V2, respectively.

  The voltage command V * takes the first value V1 from the period t12 to the period t13, falls at the end of the period t13 (the start of the period t14), and the intermediate value (the difference between this and the intermediate value in the period t11 is irrelevant). And fall at the end of the period t14 (the start of the period t15) and take the second value V2. The voltage command V * takes the second value V2 from the period t15 to the period t16, rises again from the second value V2 at the end of the period t16 (the start of the period t17), and the intermediate value (intermediate between this and the periods t11 and t14). The difference from the value is unquestioned), and rises to the first value V1 at the end of the period t17 (the start of the period t18). Thereafter, the voltage command V * changes between the first value V1 and the second value V2 while providing a period for taking an intermediate value in the same manner as described above.

  In the example of FIG. 2, the shape of one voltage command V * is representatively shown. Actually, there are voltage commands V * corresponding to the number of AC voltages (phase voltages) output from the power converter 1. Here, since a three-phase AC voltage is output, phase voltage commands Vu *, Vv *, and Vw * exist.

  This voltage command V * is generated, for example, by correcting a pre-correction voltage command V ** (hereinafter also simply referred to as voltage command V **). In the example of FIG. 1, the voltage command generation unit 31 includes a voltage command calculation unit 311 and a voltage command correction unit 312. As is well known, the voltage command calculation unit 311 generates a voltage command V ** based on, for example, a command (for example, a rotation speed command) for the load 2 input from the outside. The voltage command V ** is a rectangular wave as shown in FIG. 2, and takes the maximum value V10 and the minimum value V20 alternately. However, unlike the voltage command V *, the voltage command V ** does not take an intermediate value between the maximum value V10 and the minimum value V20. The voltage command V ** does not always take a constant value during the control period. In other words, the interval between the timings when the voltage command V ** changes is not necessarily an integer multiple of the control period.

  Here, for simplicity, the first value V1 and the maximum value V10 are equal to each other, and the second value V2 and the minimum value V20 are equal to each other. In the example of FIG. 2, the voltage command V ** rises from the minimum value V20 and takes the maximum value V10 at a predetermined time point within the period t11 (see −150 ° in FIG. 2), and the predetermined time point within the period t14 ( 2), the minimum value V20 is taken from the maximum value V10. The voltage command V ** again rises from the minimum value V20 and takes the maximum value V10 at a predetermined time point (see 210 ° in FIG. 2) within the period t17.

  In the illustration of FIG. 1, since the power conversion device 1 outputs a three-phase AC voltage, the voltage command V ** includes three phase voltage commands Vu **, Vv **, and Vw **.

  The voltage command correction unit 312 corrects the voltage command V ** and generates a voltage command V *. For example, when the voltage command V ** does not change in each control period, the voltage command V ** is not corrected. That is, the voltage command V * is generated by directly adopting the value of the voltage command V **. For example, in FIG. 2, the voltage command V ** takes a constant value during the periods t10, t12 to t13, t15 to t16, and t18. Therefore, the voltage command V * coincides with the voltage command V ** during these control periods.

  When the voltage command V ** changes in the control period, the voltage command correction unit 312 corrects the voltage command V ** in the control period to an intermediate value between the maximum value V10 and the minimum value V20, and the voltage command Generate V *. For example, in FIG. 2, the voltage command V ** changes in the periods t11, t14, and t17. Therefore, during these periods, an intermediate value between the maximum value V10 and the minimum value V20 is adopted as the voltage command V *. A specific method for calculating the intermediate value will be described in detail later. The voltage command V * illustrated in FIG. 2 is generated by the above operation.

  With this operation, the switching signal generator 33 recognizes the voltage command V * for each control period and outputs the voltage command correction unit 312 regardless of whether the control period starts, ends, or is in the middle of the control period. The voltage command V * can be correctly recognized.

  The carrier generation unit 32 generates an isosceles triangular wave carrier C1 with a variable carrier period (see also FIG. 5). For example, the carrier generation unit 32 includes a counter circuit, and outputs a counter value from the counter circuit as a carrier C1. This counter circuit inputs a clock signal having a period sufficiently shorter than the carrier period. Then, the counter value is added or subtracted for each input of the clock signal. For example, every time a clock signal is input, the counter circuit continues to update by adding 1 to the counter value. Then, when the counter value matches the predetermined maximum value, or when a predetermined time elapses after the counter value matches the minimum value, the counting process of the counter circuit is switched from addition to subtraction. Each time a clock signal is subsequently input, 1 is subtracted from the counter value and the counter value is continuously updated. Then, when the counter value matches the minimum value, or when the predetermined time elapses from the timing when the count process is switched, the count process switches from subtraction to addition again. Thereafter, the same operation is repeated. As a result, an isosceles triangular wave carrier C1 is output. As is clear from this operation, the carrier C1 has a stepped shape strictly, but here, such a shape is also referred to as a triangular wave.

  In addition, the carrier generation unit 32 changes the carrier cycle of the carrier C1 in a part of the period based on the relationship between the carrier C1 and the voltage command V *. This point will be described in detail later.

<2-1. Carrier generation by carrier generation unit>
<2-1-1. Carrier generation when voltage command V * falls>
3 to 5 show examples of the voltage command V *, the carrier C1, and the switching signal S. Here, when the voltage command V * is equal to or higher than the carrier C1, the upper switching element of the corresponding phase is turned on, and the lower switching element of the corresponding phase is turned off. For example, when the u-phase phase voltage command Vu * is equal to or higher than the carrier C1, the u-phase upper switching element S1 is turned on and the u-phase lower switching element is turned off. When the voltage command V * for each phase is equal to or lower than the carrier C1, the switching element on the upper side of the corresponding phase is made non-conductive and the switching element on the lower side of the corresponding phase is made conductive.

  In the examples of FIGS. 3 to 5, the switching signal S of the upper switching element of the corresponding phase is shown. The switching signal of the lower switching element of the corresponding phase is obtained by inverting the switching signal S.

  3 to 5, the first value V1 of the voltage command V * is equal to the peak value Vc1 of the carrier C1, and the second value V2 is equal to the bottom value Vc2 of the carrier C1. 3 and 4, a fixed carrier cycle T1 is adopted as the carrier cycle of the carrier C1, and for example, the carrier cycle T1 is twice the control cycle. For example, the control cycle is a period between the time when the carrier C1 takes the peak value Vc1 and the time when the carrier C1 takes the bottom value Vc2.

  Referring to FIG. 3, in the control period in which voltage command V * takes first value V1, voltage signal V * is greater than or equal to carrier C1, and therefore switching signal S is activated. Therefore, in this period, the upper switching element becomes conductive.

  In the period t22 following the period t21 in which the voltage command V * takes the first value V1, the voltage command V * takes an intermediate value. In this period t22, the carrier C1 monotonously increases with time. Therefore, at this time, after the update timing t2 at which the voltage command V * is updated from the first value V1 to the intermediate value (this is the boundary between the periods t21 and t22), the carrier C1 first takes the intermediate value. The rate of change of carrier C1 with respect to time is positive. Here, the rate of change of the carrier C1 with respect to time is positive over a period t22 in which the voltage command V * is reduced to take an intermediate value.

  In this case, at the beginning of the period t22 (immediately after the update timing t2, the same applies hereinafter), the voltage command V * is larger than the carrier C1. Therefore, the voltage command V * continues to be equal to or higher than the carrier C1 before and after the boundary between the periods t21 and t22 (before and after the update timing t2, and so on). Therefore, the switching signal S remains active before and after the boundary between the periods t21 and t22. Therefore, the upper switching element maintains conduction before and after the boundary between the periods t21 and t22. Then, after the time point when the carrier C1 coincides with the voltage command V * (intermediate value), the voltage command V * becomes equal to or less than the value of the carrier C1, so that the switching signal S is inactive. Thereby, an upper side switching element switches from conduction | electrical_connection to non-conduction.

  In the example of FIG. 4 as well, the voltage command V * takes an intermediate value in the period t22 following the period t21 in which the voltage command V * takes the first value V1. However, in the illustration of FIG. 4, the carrier C1 monotonously decreases with time in the period t22. In other words, after the update timing t2, the rate of change of the carrier C1 is negative when the carrier C1 first takes an intermediate value. Here, the rate of change with respect to time of the carrier C1 is negative over a period t22 in which the voltage command V * is reduced to take an intermediate value.

  In this case, the voltage command V * is smaller than the value of the carrier C1 at the beginning of the period t22. Therefore, the switching signal S becomes inactive at the beginning of the period t22. Therefore, before and after the boundary between the periods t21 and t22, the upper switching element is switched from conducting to non-conducting. In addition, the switching signal S becomes active after the point in time t22 when the carrier C1 coincides with the voltage command V * (intermediate value). Therefore, the upper switching element is switched to conduction again. Since the voltage command V * falls to the second value V2 at the end of the period t22, the switching signal S is deactivated after the period t22. Therefore, the upper switching element switches to non-conduction again.

  As described above, in the illustration of FIG. 3, the switch state of the upper switching element is switched once, whereas in the illustration of FIG. 4, the switch state of the upper switching element is switched three times. Since switching loss occurs every time the switch state is switched, it is desirable that the number of times of switching is small.

  Therefore, after the update timing t2 when the voltage command V * decreases, the carrier generation unit 32 sets the polarity of the rate of change of the carrier C1 at the time when the carrier C1 first takes an intermediate value to the prediction timing t1 before the update timing t2. To predict. In other words, the increase / decrease of the carrier C1 in the period t22 is predicted at the prediction timing t1.

  When it is predicted at the prediction timing t1 that the carrier C1 is reduced in the period t22, the carrier generation unit 32 generates the carrier C1 as follows. That is, as illustrated in FIG. 5, for example, one carrier cycle after the prediction timing t1 and before the update timing t2 is changed. Thereby, after the update timing t2, the carrier C1 is generated so that the rate of change of the carrier C1 becomes positive at the time when the carrier C1 first takes the intermediate value.

  For example, in FIG. 4, the carrier period of the carrier unit C11 before the period t22 is changed to 1.5 times the carrier period T1, as shown in FIG. Here, the carrier unit portion is a portion of the carrier C1 in units of the carrier cycle, and an increasing slope portion that increases with the passage of time and a reduction that decreases continuously with the passage of time. It refers to a pair with an inclined part. For example, a portion having one mountain shape or a portion having one valley shape is grasped as the carrier unit portion. In the following, as an example, a portion having one mountain shape is grasped as the carrier unit portion.

  In the illustration of FIG. 5, the carrier period T2 of the carrier unit portion C11 is 1.5 times the carrier cycle T1 of other carrier unit portions. Thereby, the phase of the carrier C1 after the carrier unit C11 can be shifted by 180 ° from the carrier C1 of FIGS. Accordingly, the carrier C1 increases in the period t22 as shown in FIG.

  As a result, the switching signal S remains active before and after the boundary between the periods t21 and t22, as in the description with reference to FIG.

  However, in the illustration of FIG. 5, the amplitude of the carrier unit C11 is increased in order to increase the carrier period of the carrier unit C11. In this case, as shown in FIG. 5, it is necessary to increase the voltage command V * at the same increase rate or more. This is because the active / inactive state of the switching signal S changes if the magnitude relationship between the voltage command V * and the carrier unit C11 changes as the peak value increases. Therefore, in FIG. 5, the voltage command V * to be compared with the carrier unit C11 is equal to or higher than the peak value Vc1 of the increased carrier unit C11 so that the magnitude relationship between the voltage command V * and the carrier unit C11 does not change. It is updating to the value. FIG. 5 illustrates a case where the voltage command V * takes the value 1.5Vc1 in the carrier unit C11 in response to the carrier cycle T2 of the carrier unit C11 being 1.5 times the carrier cycle T1. Yes.

  As described above, during the period in which the voltage command V * takes the first value V1, the switching signal S remains active, and the switching signal S also remains active before and after the boundary between the periods t21 and t22. Therefore, the number of switching times can be reduced.

  Moreover, according to the present embodiment, it is not necessary to generate a plurality of types of carriers in advance in order to reduce the number of times of switching. As an aspect of generating a plurality of types of carriers in advance, for example, two counter circuits are used to generate a monotonically increasing sawtooth carrier and a monotonically decreasing sawtooth carrier, and either one of them is generated in each period. A mode in which is appropriately selected is conceivable. However, in this embodiment, since a plurality of counter circuits are not required, the configuration of the carrier generation unit 32 can be simplified.

  In the illustration of FIG. 5, the carrier period is increased by increasing the amplitude of the carrier unit C11. This can be realized, for example, by increasing a reference value (a maximum value for the counter value or a reference value for the elapsed time) when switching from addition to subtraction in the counter circuit.

  Of course, the carrier period may be increased by reducing the rate of change (degree of inclination) of the carrier C1. However, in order to reduce the rate of change of the carrier C1, it is necessary to lengthen the clock cycle of the clock signal input to the counter circuit. Such a change in the clock cycle requires the use of a frequency divider or the like. On the other hand, changing the reference value is simple because the voltage value or the like may be changed. Therefore, it is easier to change the carrier cycle if the peak value of the carrier unit C11 is changed.

  In the present embodiment, the first value V1 is described as being equal to the peak value Vc1, but the first value V1 may be larger than the peak value Vc1 of the carrier C1. Even in this case, since the voltage command V * is equal to or higher than the carrier C1 during the period in which the voltage command V * takes the first value V1, the switching signal S is activated during this period. Similarly, the second value V2 may be smaller than the bottom value Vc2 of the carrier C1.

  Moreover, in this Embodiment, the carrier production | generation part 32 changes a carrier period in the one part period after the prediction timing t1. Therefore, a sufficient time for changing the carrier cycle is required between the prediction timing t1 and the update timing t2. For example, in FIG. 5, the carrier period of one carrier unit C11 is changed to 1.5 times the carrier period T1. Therefore, the prediction timing t1 is before the update timing t2 by an amount equal to or more than the sum of the three control cycles (1.5 times the carrier cycle T1) and the time required for prediction. Assuming that the time required for prediction is shorter than the control cycle, the prediction timing t1 is at least four control cycles before the update timing t2.

  Hereinafter, an example of a specific operation of the control device 3 will be described in detail. For example, the carrier generation unit 32 has a control period (hereinafter referred to as a prediction control period: m = 4 in FIGS. 3 to 5) after the m control period (m = 4) for each control period. It is predicted whether or not a control period (hereinafter referred to as a voltage drop control period) in which * decreases and takes an intermediate value (in FIG. 3 and FIG. 4, the case where the predicted control period is the period t22 is illustrated, and the period t22 is A case corresponding to a voltage drop control period is exemplified).

  This prediction can be made based on, for example, the phase of voltage command V ** (hereinafter referred to as voltage phase command) δ * (0 ° ≦ δ * <360 °). Referring to FIG. 2, the voltage phase command δ * at the rising time of the rectangular wave voltage command V ** is, for example, 210 °, and the voltage phase command δ * at the falling time of the voltage command V ** is, for example, 30. Set to °. At this time, the voltage command V * takes an intermediate value in a period t14 including a time point when the voltage phase command δ * becomes 30 °. Therefore, the period t14 including the time point when the voltage phase command δ * becomes 30 ° corresponds to the period t22 in FIGS. Therefore, the carrier generation unit 32 predicts whether or not the prediction control period corresponds to the voltage drop control period by determining whether or not the time point when the voltage phase command δ * is 30 ° is included in the prediction control period. it can.

  Therefore, the carrier generator 32 inputs the phase δ * of the current voltage command V **. Then, the voltage phase command δ [n + m] * in the prediction control period is calculated. For example, as the voltage phase command δ *, a voltage phase corresponding to the central time point of each control period is employed. The voltage phase command δ [n] * (FIGS. 3 to 5) in the period starting from the predicted timing t1 is generated when the voltage command calculation unit 311 generates the voltage command V **. The voltage phase command δ [n + k] * (k = 1, 2, 3...) Is obtained by adding the phase (= k · Δδ) for k control cycles to the voltage phase command δ [n] *. be able to. Since one control cycle tt is a predetermined time, the phase Δδ for one control cycle can be obtained by obtaining the cycle TT of the voltage command V ** (Δδ = 360 · tt / TT). For example, the period of the voltage command V ** may be measured by measuring the period of the voltage command V ** one cycle before. As the phase Δδ, for example, the difference between the voltage phase commands δ [n−2] and δ [n−1] in the immediately preceding two control cycles may be adopted, or when the load 2 is a synchronous motor. The calculation may be performed in a known manner based on the rotation speed of the electric motor.

  When the voltage phase command δ [n + m] * satisfies the following expression (1), it is predicted that the predicted control period corresponds to the voltage drop control period. That is, when the expression (1) is satisfied, the time point when the voltage phase command δ [n + m] * is 30 ° is included in the prediction control period, so the prediction control period corresponds to the voltage reduction control period. It is predicted.

  30 ° −Δδ <δ [n + m] * <30 ° + Δδ (1)

  When it is predicted that the prediction control period corresponds to the voltage drop control period, the carrier generation unit 32 estimates the increase / decrease of the carrier C1 in the prediction control period. The increase / decrease of the carrier C1 in the control period after the even number of control cycles is the same as the increase / decrease of the carrier C1 in the current control period (the control period having the prediction timing t1 as a start), and the odd number The difference between the increase / decrease of the carrier C1 in the control period after the minute control cycle is opposite to the increase / decrease in the carrier C1 in the current control period. Therefore, the increase / decrease of the carrier C1 in the prediction control period can be predicted based on the increase / decrease of the carrier C1 in the current control period and the even / oddness of m.

  When the carrier C1 is predicted to increase in the voltage drop control period (shown as the period t22 in FIGS. 3 to 5), the carrier C1 is generated while maintaining the carrier period T1, as shown in FIG. On the other hand, when it is predicted that the carrier C1 is reduced in the voltage drop control period, the carrier generation unit 32 generates the carrier C1 by setting the carrier period of the carrier unit C11 to 1.5 times the carrier period T1. Moreover, the carrier generation part 32 returns a carrier period to the carrier period T1 again after the carrier unit part C11. Thereby, as shown in FIG. 5, the carrier C1 can be increased in the period t22.

  Here, the carrier cycle T1 is described as being twice the control cycle. However, in order to maintain the state of the switching signal before and after the update timing t2, the control cycle does not have to be twice the carrier cycle T1. In short, when (i) when the carrier C1 takes an intermediate value for the first time after the update timing t2, it is predicted at the prediction timing t1 that the rate of change of the carrier C1 is negative. (Ii) the update timing t2 After that, when the carrier C1 first takes the intermediate value, the carrier period is changed in a part of the period after the prediction timing t1 so that the rate of change of the carrier C1 becomes positive, and (iii) the carrier period The voltage command V * may be determined so as to maintain the magnitude relationship between the voltage command V * and the carrier C1 during the period when is changed.

<2-1-2. Carrier generation when voltage command V * rises>
6 to 8 show examples of the voltage command V *, the carrier C1, and the switching signal S. FIG. Referring to FIG. 6, in a period in which voltage command V * takes second value V2, voltage command V * is equal to or lower than carrier C1, and therefore switching signal S is deactivated. Therefore, in this period, the upper switching element is non-conductive.

  In the example of FIG. 6, the voltage command V * takes an intermediate value in a period t32 following the period t31 in which the voltage command V * takes the second value V2. Further, in this period t32, the carrier C1 monotonously decreases with time. Therefore, at this time, after the update timing t4 when the voltage command V * is updated from the second value V2 to the intermediate value, the rate of change of the carrier C1 is negative when the carrier C1 first takes the intermediate value. Here, the rate of change with respect to time of the carrier C1 is negative over a period t32 in which the voltage command V * increases and takes an intermediate value.

  In this case, at the beginning of the period t32 (immediately after the update timing t4, the same applies hereinafter), the voltage command V * is smaller than the carrier C1. Therefore, the voltage command V * continues to be equal to or lower than the carrier C1 before and after the boundary between the periods t31 and t32 (before and after the update timing t4, hereinafter the same). Therefore, the switching signal S remains inactive before and after the boundary between the periods t31 and t32. Therefore, the upper switching element maintains non-conduction before and after the boundary between the periods t31 and t32. Then, after the time point when the carrier C1 coincides with the voltage command V * (intermediate value), the switching signal S becomes active. As a result, the upper switching element is switched from non-conduction to conduction.

  In the example of FIG. 7 as well, the voltage command V * takes an intermediate value in the period t32 following the period t31 in which the voltage command V * takes the second value V2. However, in the illustration of FIG. 7, the carrier C1 monotonously increases with time in the period t32. In other words, after the update timing t4, the rate of change of the carrier C1 becomes positive when the carrier C1 first takes an intermediate value. Here, the rate of change of the carrier C1 with respect to time is positive over a period t32 in which the voltage command V * increases and takes an intermediate value.

  In this case, the voltage command V * is larger than the carrier C1 at the beginning of the period t32. Accordingly, the switching signal S becomes active at the beginning of the period t32. Therefore, the upper switching element is switched from non-conduction to conduction before and after the boundary between the periods t31 and t32. In addition, the switching signal S becomes inactive after the time point when the carrier C1 coincides with the voltage command V * (intermediate value) during the period t32. Therefore, the upper switching element switches to non-conduction again. Since the voltage command V * rises to the first value V1 at the end of the period t32, the switching signal S becomes active after the period t32. Therefore, the upper switching element is switched to conduction again.

  As described above, in the illustration of FIG. 6, the switch state of the upper switching element is switched once, whereas in the illustration of FIG. 7, the switch state of the upper switching element is switched three times.

  Therefore, after the update timing t4 when the voltage command V * increases, the carrier generation unit 32 predicts the polarity of the rate of change at the time when the carrier C1 first takes an intermediate value at the prediction timing t3 before the update timing t4. . In other words, the increase / decrease of the carrier C1 in the period t32 is predicted at the prediction timing t3.

  Then, when it is predicted that the change rate at the time point is positive, as shown in FIG. 8, for example, by changing one carrier cycle after the prediction timing t3, the change rate at the time point becomes negative. The carrier C1 is generated as follows. For example, in FIG. 7, the carrier cycle of the carrier unit C21 immediately before the period t32 is changed to 1.5 times the carrier cycle T1, as shown in FIG. In the example of FIG. 8 as well, the carrier period of the carrier unit portion C21 is increased by increasing the amplitude (for example, peak value) of the carrier unit portion C21, similarly to the carrier unit portion C11 of FIG.

  In FIG. 7, the carrier unit portion C21 decreases in the period t31 and increases in the period t32. However, as shown in FIG. Will be reduced over time. As a result, the voltage command V * falls below the carrier C1 at the beginning of the period t32. Therefore, the switching signal S remains inactive at the beginning of the period t32, and the upper switching element maintains non-conduction before and after the boundary between the periods t31 and t32.

  Thereby, the switching signal which reduced the frequency | count of switching can be produced | generated. Moreover, the configuration of the carrier generation unit 32 can be simplified as compared with the case where a plurality of types of carriers are generated.

  7 and 8, the carrier period of the carrier unit C21 immediately before the period t32 is increased. Therefore, the prediction timing t3 may be before the update timing t4 by an amount equal to or greater than the sum of the two control periods (carrier unit part C21) and the time required for prediction. In the illustration of FIG. 7, the prediction timing t3 is a timing three control cycles before the update timing t4.

  Hereinafter, an example of a specific operation of the control device 3 will be described in detail. First, the carrier generation unit 32 is a period in which the prediction control period after the n1 (n1 ≧ 3) control period takes an intermediate value by increasing the voltage command V * for each control period (hereinafter referred to as a voltage increase control period). It is predicted whether it corresponds to. 6 to 8 illustrate a case where the prediction control period and the voltage increase control period correspond to the period t32. Since this prediction is the same as the prediction of whether or not the prediction control period after the n1 control cycle corresponds to the voltage drop control period, repeated description is avoided.

  When it is predicted that the predicted control period after the n1 control cycle corresponds to the voltage increase control period, the increase / decrease of the carrier C1 in the predicted control period after the n control cycle is predicted. The increase / decrease of the carrier C1 in the prediction control period after the n1 control cycle can be predicted based on the increase / decrease of the carrier C1 in the current control period and the even / oddness of n1.

  When it is predicted that the carrier C1 will decrease in the voltage increase control period, the carrier C1 is generated while maintaining the carrier cycle T1, as shown in FIG. On the other hand, when it is predicted that the carrier C1 will increase in the voltage increase control period, the carrier generation unit 32 changes the carrier cycle of the carrier unit C21 after the prediction timing t3 to 1.5 times the carrier cycle T1, Carrier C1 is generated. Thereby, as shown in FIG. 8, the carrier C1 can be reduced in the voltage increase control period.

  Thereby, the frequency | count of switching can be reduced. In this embodiment, in short, (i) after the update timing t4, when the carrier C1 takes an intermediate value for the first time, it is predicted at the prediction timing t3 that the rate of change of the carrier C1 is positive. (Ii) After the update timing t4, the carrier cycle is changed in a part of the period after the prediction timing t3 so that the rate of change of the carrier C1 becomes negative at the time when the carrier C1 first takes an intermediate value. (Iii) The voltage command V * may be determined so as to maintain the magnitude relation between the voltage command V * and the carrier C1 during the period in which the carrier cycle is changed.

<2-2. Prediction timing>
In the above example, to determine the carrier C1 in the period t22, the period of at least 4 control periods ahead is predicted, and in order to determine the carrier C1 in the period t32, the period of at least 3 control periods ahead is predicted. Yes. Therefore, the carrier C1 is generated corresponding to both the periods t22 and t32 by always predicting whether or not the period ahead of at least four control cycles corresponds to the period t22 and whether it corresponds to the period t32. can do.

<2-3. Change of carrier unit amplitude>
<2-3-1. Changing the bottom value of the carrier unit>
In the example described above, by increasing the peak value of the carrier unit portion, the amplitude of the carrier unit portion is increased, and thus the carrier cycle is increased. However, the carrier period may be increased by reducing the bottom value of the carrier unit part to increase the amplitude of the carrier unit part. In this case, the carrier unit has a valley shape.

<2-3-2. Reduction of carrier unit amplitude>
In the example described above, the carrier period of the carrier unit portion is increased. However, the period of the carrier unit may be reduced.

  For example, when predicting that the rate of change of the carrier C1 in the period t22 is negative at the prediction timing t1 illustrated in FIG. 4, the carrier generation unit 32 determines the carrier period in a part of the period after the prediction timing t1 as follows: For example, it may be reduced as shown in FIG. More specifically, the carrier period of the carrier unit part C12 (carrier unit part of a set of periods t21 and t22) in FIG. 4 is changed to one half of the carrier period T1 as shown in FIG. Thereby, the carrier C1 can be increased in the period t22.

  Moreover, in this case, the carrier cycle can be changed in time even if the prediction timing t1 is closer to the update timing t2. More specifically, in FIGS. 4 and 9, a prediction timing t1 'that is two control cycles before the update timing t2 can be employed.

  It is preferable to bring the prediction timing closer to the update timing as described below. The period of the voltage command V * may be changed to change the rotation speed of the load 2. If the rise (or fall timing) of the voltage command V * is advanced at a timing between the prediction timing and the update timing, the carrier cycle may not be changed by the period t22 or the period t32. For example, in FIG. 9, if the fall of the voltage command V * is accelerated and the voltage command V * takes an intermediate value in the period t21, the carrier C1 cannot be generated appropriately. Therefore, in order to avoid such a situation, it is desirable that the time between the prediction timing and the update timing is short.

  Therefore, in terms of bringing the prediction timing closer to the update timing, it is desirable to reduce the carrier period rather than increasing it.

  In the present embodiment, the control cycle is a half cycle of the carrier cycle T1, and the point in time when the carrier C1 takes the peak value or the bottom value is the boundary between the control cycles. When the carrier period of the carrier unit part C12 is changed to one half of the carrier period T1, the boundary of the control period is different from the case where the carrier period T1 is changed to 1.5 times (FIG. 8). The time point at which the carrier C1 takes the peak value or the bottom value is maintained. More specifically, referring to FIG. 8, in the period corresponding to carrier unit C21, the boundary between the control periods corresponds to a value that is neither the peak nor the bottom of carrier unit C12. On the other hand, referring to FIG. 9, in the period corresponding to carrier unit C12, the boundary between the control periods corresponds to the bottom value of carrier unit C12.

  A voltage command generation unit 31 that calculates a voltage command V * for each control cycle is known on the assumption that the boundary between control cycles coincides with the time when the carrier C1 takes a peak value or a bottom value. As described above, when the carrier cycle T1 is changed to ½, the boundary between the control cycles coincides with the time point when the carrier C1 takes the peak value or the bottom value. The generation unit 31 can be used as it is. This leads to a reduction in calculation load.

  In addition, when detecting (sampling) various amounts of the load 2 (for example, current flowing through the load 2) for the calculation of the control command V **, the control cycle (sampling cycle) is constant. Contributes to improvement of performance.

<2-4. Changes in carrier cycle>
In the above example, the carrier period of only one carrier unit is changed. However, it is not always necessary to change the carrier period of one carrier unit, and the carrier periods of a plurality of carrier units may be changed.

  For example, as shown in FIG. 10, the carrier cycle of the two consecutive carrier unit parts C11 and C13 may be changed to 1.25 times the carrier cycle T1 to generate the carrier C1. This also makes it possible to shift the phase of the carrier C1 after the carrier unit parts C11 and C13 by 180 °. Therefore, the carrier C1 increases in the period t22.

  More generally, the carrier period of the N carrier units may be changed to (N + 0.5) / N times the carrier period T1. In this case, however, it is necessary to predict whether or not at least the (2 · N + 2) control period ahead corresponds to the period t22 (or the period t32) and whether the carrier C1 is increased or decreased. In the illustration of FIG. 10, it is 6 (= 2 · 2 + 2) control cycle before the update timing t2.

  Also, as shown in FIG. 10, when increasing the peak value of N carrier unit parts, the voltage command generation unit 31 determines that the voltage command V * corresponding to the N carrier unit parts is increased after the increase of the carrier unit parts. It is determined to be equal to or higher than the peak value.

  Now, when the number of carrier unit parts for which the carrier period is to be changed is increased, it is necessary to advance the prediction timing as described above. Therefore, in terms of bringing the prediction timing closer to the update timing, it is desirable that the carrier cycle change target is only one carrier unit.

<3. Calculation cycle>
In the above example, although prediction is performed for each control cycle, the present invention is not limited to this. For example, the prediction may be performed every twice the control cycle (hereinafter referred to as the calculation cycle). An example will be described.

  At this time, as the voltage phase command δ *, as illustrated in FIG. 11, the voltage phase at the center of the period for each calculation cycle is adopted. Further, in FIG. 11, the carrier C1 has a mountain shape in the period for each calculation cycle. As shown in FIG. 11, when included in the first half of the calculation period (period for each calculation period) at which the voltage phase reaches 30 °, the carrier C1 takes the intermediate value first after the update timing t2. The rate of change of the carrier C1 at the time becomes positive. Therefore, the switching frequency is small.

  On the other hand, as shown in FIG. 12, when the time point when the voltage phase becomes 30 ° is included in the latter half of the calculation period, the change of the carrier C1 at the time when the carrier C1 first takes the intermediate value after the update timing t2. The rate becomes negative.

  Therefore, after the update timing t2, is the first half of the calculation period included when the voltage phase becomes 30 ° in order to predict the polarity of the rate of change of the carrier C1 when the carrier C1 first takes an intermediate value? , Predict whether it will be included in the second half. This prediction can be performed based on the voltage phase command δ * for each calculation period. Here, the voltage phase command δ [n + 2] * in the calculation period two calculation cycles ahead is used. More specifically, when the phase Δδ1 for one calculation cycle is introduced, the voltage phase becomes 30 ° when the voltage phase command δ [n + 2] * is larger than 30 ° and smaller than (30 ° + Δδ1 / 2). When the time point can be predicted to be included in the first half of the calculation period two calculation cycles ahead, and the voltage phase command δ [n + 2] * is greater than (30 ° −Δδ1 / 2) and smaller than 30 °, the voltage phase Can be predicted to be included in the latter half of the calculation period two calculation cycles ahead.

  Then, when the voltage phase command δ [n + 2] * is larger than (30 ° −Δδ1 / 2) and smaller than 30 °, as shown in FIG. 13, the carrier generating unit 32, for example, of the carrier unit C11 Change the carrier period to 1.5 times.

<4. Example of specific generation method of voltage command V *>
Here, as a reference, a specific method for calculating the intermediate value Vmid of the voltage command V * will be described. For example, the voltage command V ** is a rectangular wave and falls at a voltage phase of 30 ° and rises at a voltage phase of 210 ° as shown in FIG. FIG. 14 shows an enlarged example of the voltage command V * and the voltage command V **. Here, the voltage command correction unit 312 corrects the voltage command V ** for each control cycle to calculate the voltage command V *. FIG. 14 shows the vicinity of the portion where the voltage command V ** falls.

  In FIG. 14, the time point at which the voltage phase becomes 30 ° is included in one period T among the periods for each control cycle. In FIG. 14, a period between the central time point of the period T and the time point when the voltage phase becomes 30 ° is indicated by a period Tv1.

  The voltage command correction unit 312 determines that the ratio of the amplitude (V10−V20) of the voltage command V ** and the difference between the intermediate value Vmid and the minimum value V20 (Vmid−V20) is equal to the period T and the voltage command V **. The intermediate value Vmid is calculated so that the ratios to the period in which the maximum value V10 is taken ((T / 2 + Tv1 in FIG. 11)) are equal to each other. Therefore, the intermediate value Vmid is expressed by the following formula.

  Vmid = V20 + (V10−V20) · (T / 2 + Tv1) / T (2)

  In FIG. 14, the voltage phase command δ [n] * at the center time point of the period T is smaller than 30 °. Assuming that the rotational speed is substantially constant at this time, the following equation is geometrically satisfied.

  δ [n] * − δ [n−1] *: 30 ° −δ [n] * = T: Tv1 (3)

  When the period Tv1 is obtained using Expression (3), the following expression is derived.

  Tv1 = T ・ (30 ° -δ [n] *) / (δ [n] *-δ [n-1] *) (4)

  Substituting equation (4) into equation (2) leads to the following equation:

  Vmid = V20 + (V10-V20) ・ {1/2 + (30 ° -δ [n] *) / (δ [n] *-δ [n-1] *)} (5)

  Maximum value V10 and minimum value V20 are set in advance, and voltage phase commands δ [n] * and δ [n−1] * are calculated by voltage command calculation unit 311. The voltage command correction unit 312 calculates the intermediate value Vmid based on the equation (5).

  FIG. 15 includes a time point at which the voltage phase becomes 30 ° in the period T, and the voltage phase command δ [n] * is larger than 30 °. In this case, the period during which the voltage command V ** takes the maximum value V10 is represented by (T / 2−Tv1). Therefore, equation (2) is transformed into the following equation.

  Vmid = V20 + (V10−V20) · (T / 2−Tv1) / T (6)

  Further, assuming that the rotation speed is substantially constant in FIG. 12, the following equation is geometrically satisfied.

  δ [n] * − δ [n−1] *: δ [n] * − 30 ° = T: Tv1 (7)

  When the period Tv1 is obtained using Expression (7), the following expression is derived.

  Tv1 = T · (δ [n] *-30 °) / (δ [n] *-δ [n-1] *) (8)

  Substituting equation (8) into equation (6) leads to the following equation:

  Vmid = V20 + (V10-V20) ・ {1 / 2- (δ [n] *-30 °) / (δ [n] *-δ [n-1] *)} (9)

  Expressions (9) and (5) are the same expression. Therefore, also in this case, the voltage command correction unit 312 may calculate the intermediate value Vmid based on the equation (5).

  In this example, although the voltage phase command δ * in the period for each control cycle is used, the voltage phase command δ * in a period twice the control cycle (calculation cycle) may be used. In this case, if it is noted that the difference between the voltage phase commands δ [n] * and δ [n−1] * corresponds to twice the control cycle, the voltage commands V * for two control cycles are similarly set. Can be calculated.

  The voltage command V * is assumed to fall at a voltage phase of 30 °, but may rise at an arbitrary electrical angle.

  The various embodiments described above can be appropriately combined as long as the functions of each other are not impaired.

DESCRIPTION OF SYMBOLS 1 Power converter 31 Voltage command generation part 32 Carrier generation part 33 Switching signal generation part C1 Carrier P1, P2 input terminal

Claims (7)

A device (3) for controlling a power converter (1) having a switching element connected in series between a pair of input terminals to which a DC voltage is applied, and converting the DC voltage into an AC voltage. ,
A voltage command generator (31) for updating the voltage command (V *) for the AC voltage;
A carrier generator (32) for generating a triangular wave carrier (C1) with a variable carrier period;
Based on the comparison between the voltage command and the carrier to generate a switching signal (S), comprising a switching signal generation unit (33) for providing the switching signal to the switching element,
First update timing (t2) at which the voltage command is updated from a first value (V1) equal to or higher than the peak value (Vc1) of the carrier to an intermediate value between the peak value and the bottom value (Vc2) of the carrier After that, when the carrier first takes the intermediate value, it is predicted at the first prediction timing (t1) before the first update timing that the rate of change of the carrier with respect to time is negative. In addition,
(i) The carrier generation unit changes the carrier cycle in a part of the period after the first prediction timing, so that the carrier first takes the intermediate value after the first update timing. Generating the carrier so that the rate of change of the carrier is positive at
(ii) The voltage command generation unit determines the voltage command so as to maintain a magnitude relationship between the voltage command and the carrier in a period in which the carrier cycle is changed,
And / or
After the second update timing (t4) when the voltage command is updated from the second value (V2) equal to or lower than the bottom value to the intermediate value, the carrier first takes the intermediate value when the carrier takes the intermediate value. When predicting that the rate of change is positive at the second prediction timing (t3) before the second update timing,
(iii) The carrier generation unit changes the carrier period in a part of the period after the second prediction timing, so that the carrier takes the intermediate value first after the second update timing. Generating the carrier such that the rate of change of the carrier is negative at
(iv) The control device for the power conversion device, wherein the voltage command generation unit determines the voltage command so as to maintain a magnitude relationship between the voltage command and the carrier in a period in which the carrier cycle is changed.   The control device for a power conversion device according to claim 1, wherein the carrier generation unit (32) reduces the carrier cycle in the partial period. The voltage command takes a constant value for each control cycle that is an integral multiple of a half cycle of the carrier,
The part of the carrier that is subject to change of the carrier period is only one of a mountain-shaped part or a valley-shaped part with the carrier period as a unit,
The control apparatus for a power conversion device according to claim 2, wherein the carrier generation unit (32) changes the carrier cycle to one half in the partial period.   The control device for a power conversion device according to claim 1, wherein the carrier generation unit (32) increases the carrier cycle in the partial period.   The power conversion according to any one of claims 1 to 4, wherein the carrier generation unit (32) changes the carrier cycle by changing an amplitude of the carrier (C1) in the partial period. Control device for the device.   The part of the carrier that is subject to change of the carrier period is only one of a mountain-like part or a valley-like part with the carrier period as a unit, and any one of claims 1, 2, 4, and 5 The control apparatus of the power converter device of description. A control device (3) for a power converter according to any one of claims 1 to 6;
A power conversion system comprising the power conversion device (1).

Images