Gate driver device

Abstract

A control device (1) for a rotating machine for applying an AC voltage based on a DC voltage from a DC power supply (13) to a rotating machine (16) through a power converter (14), comprising: a voltage command generator (10) that generates a voltage command value, a carrier wave generation unit (11), and a comparator (12) that determines the switching operation of the power converter using the voltage command value and the output of the carrier wave generation unit. The carrier wave generation unit (11) has a carrier wave corrector (20) for correcting the frequency of a carrier wave.Under a condition that an increase in the number of times of switching per period of the electrical angle is suppressed as much as possible, the switching is performed so that the peak current is not increased in a region where the magnitude of a current value in the current information about the rotating machine (16) is more than a predetermined magnitude, so that an increase in the peak current is suppressed without increasing the losses due to the switching operation, so that the rotating machine (16) and the power converter (14) are protected.

Description

Technical FieldThe present invention relates to a control device for a rotating machine.Prior ArtWhen a rotating machine controller performs pulse width modulation (PWM) control for the rotating machine in a high-speed rotation range, synchronous PWM control is generally used to ensure that the voltage pulses per period of the electrical angle are symmetrical. Regarding synchronous PWM control, a synchronous control with triangular wave comparison that determines the PWM duty by comparing a triangular wave with a modulation signal can maintain the symmetry of the voltage pulses with a simple configuration, and is thus widely used.Meanwhile, it is desirable that the number of times a shift is performed is made as small as possible to reduce losses due to the shift. Here, the number of times of switching is defined as the number of times that switching is performed by one converter per period of the electrical angle, i.e., the sum of the number of times of turning on and the number of times of turning off. For example, in the nine-pulse synchronized mode, the number of times of the switching operation is 18.In the six-pulse synchronized mode, the number of times of switching is 12, and when the number of times of switching is decreased, the voltage harmonics and the current harmonics increase, causing a problem that the peak of the phase current (hereinafter, peak current) is increased. In an application such as factory automation (FA), air conditioner, work machine, aircraft, train, and automobile in which a control device for a rotating machine is used, if increase in peak current cannot be sufficiently suppressed, demagnetization and element failure are caused. Consequently, it is desirable to achieve a reduction in both the number of times of switching and the peak current.For example, in Patent Document 1, in the asynchronous PWM control configuration in a triangular wave comparison method, the carrier wave frequency is increased in a range where the amplitude of the phase current is large, so that an increase in the peak current is suppressed. In Patent Document 2, in the configuration of synchronous PWM control using a triangular wave comparison method, the carrier wave frequency in a specific period of the carrier wave is multiplied by an integer, and the period in which the carrier wave frequency is multiplied by an integer does not span two periods, so that an increase in electromagnetic interference is suppressed.Literature DirectoryPatent DocumentsPatent Document 1: Japanese Patent Application Laid-Open JP-A-2-168 895Patent Document 2: Japanese Patent Application Laid-Open JP 2012-235 619 ASUMMARY OF THE INVENTIONProblem to be Solved by the InventionThe configuration according to Patent Document 1 or 2 can suppress the increase in the peak current, but has a problem that the number of times of switching increases. In addition, the number of patterns that can be used as the carrier waveform is small, and the effect of suppressing the increase in peak current is small. In addition, in order to reduce the peak current, when the carrier wave frequency is increased and the number of times of switching is increased, heat in a chip of an inverter which is a switching element becomes high, resulting in malfunction of the inverter.The present invention has been devised to solve the above problems. It is therefore an object of the present invention to suppress the increase in the peak current without increasing the losses due to switching operation, and to protect a rotating machine and a converter.Ways of Solving the ProblemA rotating machine control device according to the present invention is for applying an AC voltage from a DC voltage supplied from a DC power supply to a rotating machine through a converter, and includes: a voltage command generator that generates a voltage command value; a carrier wave generation unit that generates a carrier wave; and a comparator that determines a switching operation of the converter using the voltage command value and the output of the carrier wave generation unit, wherein the carrier wave generation unit includes a carrier wave corrector that corrects a frequency of a carrier wave as a reference and performs correction with respect to the frequency of the carrier wave as a reference, the carrier wave corrector, so that the frequency of the carrier wave is increased by a factor of more than 1.0, at least in a part of a range where the strength of a current value in current information about the rotating machine is more than a predetermined strength, and makes a correction so that the frequency of the carrier wave is decreased by a factor of 1.0 or less, at least in a part of a range where the strength of the current value in current information about the rotating machine is less than the predetermined strength, or the carrier wave corrector makes a correction so that the frequency of the carrier wave is increased by a factor of 1.0 or more, at least in a part of the range where the strength of the current value in current information about the rotating machine is more than a predetermined strength, and makes a correction, so that the frequency of the carrier wave is lowered by a factor smaller than 1.0 at least in a part of the range where the strength of the current value in the current information about the rotating machine is smaller than the predetermined strength.Effect of the inventionIn the rotating machine control device according to the present invention, under the condition that an increase in the number of times of switching per period of the electrical angle is suppressed as much as possible, the switching is performed so that the peak current is not increased in a range where the magnitude of the current value in the current information about the rotating machine is more than a predetermined magnitude, so that an increase in the peak current is suppressed without increasing the losses due to the switching operation, so that the rotating machine and the inverter can be protected.Brief Description of the DrawingsFIG. 1 is a hardware configuration diagram of a rotating machine control device according to Embodiment 1. FIG. 2 is a functional block diagram of the rotating machine control device according to Embodiment 1. FIG. 3 is a block diagram showing an internal configuration of a carrier wave generation unit according to Embodiment 1. FIG. 4 is a block diagram showing an internal configuration of a carrier wave corrector according to Embodiment 1. FIG. 5 is a block diagram showing an internal configuration of a carrier wave calculator according to Embodiment 1. FIG. 6 illustrates a carrier wave generated by a rotating machine control device in a comparative example. FIG. 7 illustrates a carrier wave obtained by correcting the carrier wave frequency in the rotating machine control device according to Embodiment 1. FIG. 8 illustrates a carrier wave obtained by correcting the carrier wave frequency and the carrier wave phase in the rotating machine control device according to Embodiment 1. FIG. 9 illustrates a carrier wave obtained by correcting the carrier wave frequency and the carrier wave phase in a case where the phase difference between voltage and current is large in the rotating machine control device according to Embodiment 1.DESCRIPTION OF EMBODIMENTSHereinafter, a preferred embodiment of the rotating machine control device according to the present invention will be described with reference to the drawings. The same or corresponding components and parts are denoted by the same reference numerals, and detailed description thereof will be omitted.Embodiment 1An example of the hardware of a rotating machine control device 1 of the present invention is shown in FIG. 1. The rotating machine control device 1 is formed of a processor 2 and a storage device 3. Although not illustrated, the storage device 3 includes a volatile storage device such as a random access memory and an auxiliary nonvolatile storage device such as a flash memory. The storage device 3 may also include an auxiliary storage device such as a hard disk instead of a flash memory.FIG. 2 is a functional block diagram of the rotating machine control device of the present embodiment. The rotating machine control device 1 includes a voltage command generator 10, a carrier wave generation unit 11, and a comparator 12. A gate signal for performing on / off control of a switching element of a converter 14 is transmitted from the comparator 12, and the voltage supplied from a DC power supply 13 is converted into AC voltage. The converted AC voltage is applied to a rotating machine 16 so that the rotating machine 16 is driven. Hereinafter, each configuration in the rotating machine control device 1 will be described in detail.The voltage command generator 10 generates a voltage command value, a voltage phase, a rotation speed, the number of pulses, and a torque command, on the basis of an input operation command and current information. Here, the operation command denotes a command torque, a command rotational speed, a current command, etc. which are input to the voltage command generator from the outside. The current information is detected from the currents for the respective phases of the rotating machine 16.As current information, a current detection value detected by a current detector 15, a current command value, or a current estimation value estimated or predicted from characteristics of the rotating machine may be used as described below. The generated voltage command value is output to the comparator 12. In addition, the voltage phase, the rotation speed, the number of pulses, and the torque command that have been generated are output to the carrier shaft generation unit 11. The current information is also input to the carrier wave generation unit 11. The voltage phase may be included as part of the information on the voltage command value.In a method of generating the voltage command value, for example, the operation command is converted into a current command, and current vectors thereof are controlled in a rotating coordinate system (d-q coordinate system), so that a three-phase voltage command value can be obtained. In addition, a three-phase voltage command value corresponding to a command rotation speed can be obtained as in a V / f constant control.The voltage phase is obtained from a rotor position that is detected or estimated by using a device such as a resolver or an encoder (not illustrated) that is a position detector mounted on the rotating machine 16 and the phases of the voltage vectors obtained from the three-phase voltage command value.As the rotational speed, a value obtained by calculation using the rotor position or a value detected by a speed detector is used.The number of pulses denotes the number of voltage pulses for performing the switching operations in one period of the electrical angle, and is also the number of carrier waves. The number of carrier waves is the number of carrier wave periods in one period of the electrical angle, and when the carrier wave is a triangular wave, it is equal to the number of upper and lower vertices thereof.The number of pulses is determined based at least on the rotational speed, and is determined in accordance with disturbances, harmonics, torque, vibrations, the calculation cycle, and the like regarding the shifting. As the number of pulses, for example, an odd number such as 15, 9, 5 or 3 is often selected because of the symmetry of the pulse waveform, but an even number such as 12 or 6 may also be selected, and a number including a decimal fraction may be selected in a case where the number of pulses is used in a plurality of periods of the electrical angle.For example, if the number of pulses per period of electrical angle is chosen to be 15.1; 9.8, or 6.5, the number of pulses will be 151, 98, or 65, respectively, over 10 periods of electrical angle.The carrier wave generation unit 11 includes a carrier wave corrector 20 and a carrier wave calculator 30, and generates a carrier wave on the basis of the current information and the voltage phase, the rotation speed, the number of pulses, and the torque command generated by the voltage command generator 10. The generated carrier wave is output to the comparator 12. The frequency of the carrier wave is generated as a product of a coefficient and the frequency of the voltage command value.The comparator 12 compares the magnitudes of the voltage command value and the carrier wave using the voltage command value generated by the voltage command generator 10 and the carrier wave generated by the carrier wave generation unit 11 so that a PWM waveform is generated, and outputs the gate signal to the inverter 14. That is, the switching operation of the inverter 14 is determined by the comparator 12 using the voltage command value and the carrier wave.The gate signal output from the comparator 12 of the rotating machine control device 1 is input to the inverter 14. The inverter 14 is connected to the DC power supply 13 and the rotating machine 16 via a wiring, and generates an AC voltage from the DC voltage supplied from the DC power supply 13 on the basis of the gate signal, and the AC voltage is applied to the rotating machine 16.As the rotational speed approaches 0, it goes without saying that the AC current and the AC voltage become a DC current and a DC voltage, and the AC current and the AC voltage include not only an AC component but also a DC component when an offset component is included.The current detector 15 detects currents iu, iv, iw for the respective phases, namely, the U phase, V phase, and W phase of the rotating machine 16. Instead of the current detected by the current detector 15, the current command value for a part or all of the respective phases may also be used, or a current estimator for predicting or estimating the current from characteristics of the rotating machine may be used, as represented by the following equation (1).In addition, the current may be detected on the side of a DC bus to calculate the currents for the respective phases. The current estimator is occasionally used as a substitute for the current detector 15 to reduce the cost. In a case where the current estimator is also used as a substitute, when the accuracy and the responsiveness of the current detector 15 are low, a current that transiently varies can be securely observed. Mathematical Expression 1Here, equation (1) is a voltage equation in fixed coordinates u, v, w on the rotating machine, and vu, vv, vw denote the phase voltages, R denotes the winding resistance, s denotes the differential operator, Lu, Lv, Lw denote the self inductances of the windings, Muv, Mvw, Mwu denote the mutual inductances between the windings, iu, iv, iw denote due phase currents, ωre denotes the angular electric velocity, φmag denotes the magnetic flux of permanent magnets, and θre denotes the angular electric position.The rotating machine 16 is assumed to be a three-phase synchronous motor or a three-phase induction motor, but may be, for example, a three-phase double winding motor, a motor such as a five-phase motor other than three-phase motors, or a field winding motor. In addition, the rotating machine 16 may be, for example, a synchronous reluctance motor, a switched reluctance motor, another synchronous motor, or a motor other than induction motors.FIG. 3 is a block diagram showing the configuration of the carrier wave generation unit 11. The carrier wave generation unit 11 includes the carrier wave corrector 20 and the carrier wave calculator 30.The carrier wave corrector 20 calculates a carrier wave frequency correction value and a carrier wave phase correction value on the basis of the current information from the current detector 15 and the information on the voltage phase, the rotation speed, and the torque command generated by the voltage command generator 10, and outputs the calculated values to the carrier wave calculator 30.The carrier wave calculator 30 corrects the carrier wave as a reference on the basis of the voltage phase, the rotation speed, and the number of pulses generated by the voltage command generator 10 on the basis of the carrier wave frequency correction value and the carrier wave phase correction value generated by the carrier wave corrector 20, and thus generates a carrier wave. The carrier wave as a reference denotes a carrier wave having a carrier wave frequency that is constant in one period of the electrical angle.FIG. 4 is a block diagram showing the internal configuration of the carrier wave corrector 20. The carrier wave corrector 20 includes a carrier wave frequency correction value calculator 21, a carrier wave phase correction value calculator 22, a correction determiner 23, and multipliers 24, 25.The carrier wave frequency correction value calculator 21 calculates the carrier wave frequency correction value on the basis of the voltage phase. With the carrier wave frequency correction value, correction is performed so that the carrier wave frequency is raised or lowered so that the number of times of switching (equivalent to the designation for the number of pulses or the number of carrier waves) in one period of the electrical angle is not changed or is not subjected to a change by 20% or more.That is, with respect to the carrier wave as a reference, correction is performed such that the frequency of the carrier wave is increased by a factor of more than 1.0, at least in a part of a range where the strength of the current value in the current information about the rotating machine 16 is more than a predetermined strength, and correction is performed such that the frequency of the carrier wave is decreased by a factor of 1.0 or less, at least in a part of a range where the strength of the current value in the current information about the rotating machine 16 is less than the predetermined strength, or correction is performed such that the frequency of the carrier wave is increased by a factor of 1.0 or more, at least in a part of the range, where the strength of the current value in the current information about the rotating machine 16 is more than the predetermined strength, and correction is performed so that the frequency of the carrier wave is lowered by a factor of less than 1.0, at least in a part of the range where the strength of the current value in the current information about the rotating machine 16 is less than the predetermined strength.Alternatively, with respect to the carrier wave as a reference, correction may be performed such that the frequency of the carrier wave is increased by a factor of more than 1.0, at least in a part of a range where the strength of the voltage command value for the rotating machine 16 is more than a predetermined strength, and correction may be performed such that the frequency of the carrier wave is decreased by a factor of 1.0 or less, at least in a part of a range where the strength of the voltage command value for the rotating machine 16 is less than the predetermined strength, or correction may be performed such that the frequency of the carrier wave is increased by a factor of 1.0 or more, at least in a part of the range where the strength of the voltage command value for the rotating machine 16 is more than the predetermined strength, Or correction may be performed so that the frequency of the carrier wave is lowered by a factor of less than 1.0, at least in a part of the range where the strength of the voltage command value for the rotating machine 16 is less than the predetermined strength.More specifically, in the present embodiment, the carrier wave frequency of the carrier wave as a reference is corrected to be raised so that the peak current becomes small at least in a part of a range where the amplitude of an AC waveform, which is current information, is large. The range where the amplitude in the current information is large denotes a range where the instantaneous value in the current information (AC waveform) is not less than a predetermined value with respect to a positive or negative peak value.For example, the value is not less than 90% of the peak value. The expression "at least in a part of the range" is used because it is not necessary that the carrier wave frequency is increased over the entire width of the range where the amplitude in the current information is large, and the correction need only be performed so as to increase the effect of reducing the peak current.In addition, the same applies to the case where the voltage command value is used instead of the current information. When the voltage command value is used, the voltage command value is input from the voltage command generator 10 to the carrier wave generation unit 11 shown in FIG. 2.Consequently, under the condition that an increase in the number of times of switching per period of the electrical angle is suppressed as much as possible, switching is performed so that the peak current is not increased in the range where the magnitude of the current value in the current information about the rotating machine is more than the predetermined magnitude, or switching is performed so that the peak current is not increased in the range where the magnitude of the voltage command value for the rotating machine is more than the predetermined magnitude, so that an increase in the peak current is suppressed without increasing the losses due to the switching operation, so that the rotating machine and the converter can be protected.When the carrier wave frequency is merely increased, the number of times of switching per period of the electrical angle is increased. Consequently, the correction is performed so that the carrier wave frequency of the carrier wave as a reference is lowered in a range where the peak current does not cause a problem, while the number of times of switching per period of the electrical angle is not increased or is not subjected to a change of 20% or more.Consequently, switching losses can be reduced. The number of times of switching is not subjected to a change by 20% or more because a numerical value such as 21, 15, 12, 9 or 6 is normally selected as a number of pulses and control is performed, but for example, when the number of times of switching is increased by 20% when control is performed with the number of pulses of 12, the number of times of switching is the same as when control is performed with the number of pulses of 15, so that the effect that the number of times of switching is not increased is reduced.As an implementation method such as a correction pattern that the peak current can be decreased without increasing the number of times of switching, may be stored in advance as a map or a function on operating points. Here, as described above, the carrier wave frequency correction value calculator 21 calculates a correction value based on the voltage phase, but it may also calculate the correction value based on the current phase, the rotor position, or the like instead of the voltage phase.The carrier wave phase correction value calculator 22 corrects the carrier wave phase and thus obtains a carrier wave phase for decreasing the peak current based on the rotation speed and the torque command. More specifically, such carrier wave phases for reducing the peak current are stored as a map or function related to operating points, so that the carrier wave phase correction value is calculated.Here, the carrier shaft phase correction value calculator 22 calculates the correction value based on the rotational speed and the torque command, but may perform the calculation based on the voltage command value, the current information, or the like. Consequently, the switching phase can be adjusted so that the effect of suppressing the increase in the peak current is improved.The carrier wave frequency correction value and the carrier wave phase correction value are designed not to merely decrease the peak current but to substantially maintain the symmetry of the PWM pulses as much as possible. More specifically, PWM pulses between 0° and 180° and PWM pulses between 180° and 360° in a voltage phase are designed to be point-symmetric, and if possible, it is preferable that PWM pulses between 0° and 90° and PWM pulses between 90° and 180°, as well as PWM pulses between 180° and 270° and PWM pulses between 270° and 360° are also designed to be line-symmetric.The correction determiner 23 determines whether or not to perform correction with correction values of the carrier wave frequency correction value calculator 21 and the carrier wave phase correction value calculator 22, on the basis of the rotational speed operating point, the torque command, the voltage command, or the like, or the peak current calculated from the current information on the current actually flowing in the rotating machine 16.For example, in a case of an operating point closer to where the peak current becomes a problem or a case where the peak current is closer to an overcurrent threshold than expected, "1" is output, for example, so that the carrier wave frequency or the phase is corrected. Conversely, in a case other than an operating point where the peak current becomes a problem or a case where the peak current is not closer to the overcurrent threshold than expected, for example, "0" is output so that the carrier wave frequency or the phase is not corrected. As described above, only one specific operating point needs to be targeted, so that it is unnecessary to perform correction at all operating points, and the control configuration can be simplified.The multiplier 24 multiplies the output of the carrier wave frequency correction value calculator 21 by the output of the correction determiner 23 and thus determines the carrier wave frequency correction value, and the multiplier 25 multiplies the output of the carrier wave phase correction value calculator 22 by the output of the correction determiner 23 and thus determines the carrier wave phase correction value. Although multipliers are used here, other means such as an adder-subtracter or a divider (e.g., a function or map) may be used instead of the multipliers.In the present configuration, correction is performed so that a carrier wave frequency and a phase are obtained so that the peak current is decreased. However, the carrier wave frequency and the phase may be corrected so that the current harmonics, the voltage harmonics, the vibration or the heat are reduced besides the peak current.FIG. 5 is a block diagram showing the internal configuration of the carrier wave calculator 30. The carrier wave calculator 30 comprises multipliers 31, 32, an adder 33, and a carrier wave generator 34.The multiplier 31 multiplies the rotational speed by the number of pulses generated from the voltage command generator 10, thus calculating a carrier wave frequency as a reference. The multiplier 32 multiplies the carrier wave frequency output from the multiplier 31 by the carrier wave frequency correction value calculated by the carrier wave frequency correction value calculator 21, and outputs a carrier wave frequency.The carrier wave frequency as a reference denotes a carrier wave frequency that is constant in one period of the electrical angle. In place of the multiplier 31, other means such as an adder-subtracter and a divider (e.g., a function or a map) may be used. The carrier wave frequency as a reference is the product of a coefficient and the frequency of the voltage command value. When the carrier wave frequency correction value is multiplied by the multiplier 32, the carrier wave frequency as a reference is further multiplied by a coefficient.The adder 33 adds the voltage phase generated from the voltage command generator 10 and the carrier wave phase correction value calculated by the carrier wave phase correction value calculator 22, and outputs a carrier wave phase synchronized with the voltage phase. In place of the adder 33, another means such as a subtracter, a divider or a multiplier (e.g., a function or a map) may be used.The carrier wave generator 34 generates and outputs a carrier wave synchronized with the voltage phase on the basis of the carrier wave frequency output from the multiplier 32 and the carrier wave phase output from the adder 33. A triangular wave is often used for the carrier wave, but a saw-tooth wave, a sine wave, or a square wave may also be used.FIG. 6 shows a voltage command value, the current, a carrier wave, and a carrier wave frequency in a rotating machine control device as a comparative example that does not include the carrier wave corrector 20. FIG. 6 shows an example in which a triangular wave is used as the carrier wave and the number of pulses is set to 9. The voltage command value and the carrier wave are synchronous with each other, and the carrier wave frequency is constant.In this comparative example, the PWM pulses are generated by comparing the strengths of the carrier wave and the voltage command value. The PWM pulses denote two values: a high value indicated when the strength of the voltage command value is larger than that of the carrier wave; and a low value indicated when the strength of the voltage command value is smaller than that of the carrier wave.In this case, the PWM pulse is in a high state in a certain portion in the vicinity of a positive peak of the current, and is in a low state in a certain portion in the vicinity of a negative peak of the current. That is, the PWM pulses are in a high-level state in the vicinity of the positive peak of the current and thus serve as a command to increase the current in the positive direction, and the PWM pulses are in a low-level state in the vicinity of the negative peak of the current and thus serve as a command to increase the current in the negative direction so that the peak current is increased.Meanwhile, FIG. 7 shows the voltage command value, the current, the carrier wave, and the carrier wave frequency in the rotating machine control device 1 of the present embodiment. Compared with FIG. 6, an example is shown in which the carrier wave frequency is corrected by using the carrier wave corrector 20.At this time, in a part of a range where the magnitude of the current value of the phase current is large, i.e., in the present embodiment, in a range of about 70° to 110° and a range of about 250° to 290°, the ranges of -20° to +20° are around the peak values, the carrier wave frequency is doubled and high. Therefore, as compared with FIG. 6, the portion (from about 80° to about 100°) that is near a positive peak of the current and in which PWM pulses are in a high level state and the portion (from about 260° to about 280°) that is near a negative peak of the current and in which PWM pulses are in a low level state can be shortened, so that an increase in the peak current can be suppressed.Meanwhile, in a part of a range where the strength of the current value is small, that is, in the present embodiment, ranges other than the above-described ranges are a range from 10° to 70°, a range from 110° to 170°, a range from 190° to 250°, and a range from 290° to 350°, the carrier wave frequency is 0.6 times and low.Consequently, the number of pulses and the number of carrier waves are not changed in one period of the electrical angle. In such a correction method, the peak current can be decreased without increasing the number of times of switching. Selection of a range where the current value is large and the carrier wave frequency is increased and selection of how much the frequency is increased are not limited to the above description, and any selection method may be used as long as increase of the peak current can be suppressed.Compared with the configuration in FIG. 7, FIG. 8 shows an example in which not only the carrier wave frequency but also the carrier wave phase is corrected. At this time, the correction of the carrier wave frequency is the same as that in FIG. 7, but the carrier wave phase is corrected by 180° compared with that in FIG. 7.When the carrier wave phase is corrected as shown in FIG. 8, the ranges in which the carrier wave frequency is increased are the same as those in FIG. 7, but the PWM pulses are in a low state in a certain portion (in the present embodiment, about a range of some degrees in the vicinity of 90°) in the vicinity of a positive peak of the current, and the PWM pulses are in a high level state in a certain portion (in the present embodiment, about a range of some degrees in the vicinity of 270°) in the vicinity of a negative peak of the current.This is based on the principle that the current in the increasing direction is changed when the PWM pulses are in a high level state, and the current in the decreasing direction is changed when the PWM pulses are in a low level state. Consequently, the configuration in FIG. 8 in which the carrier wave phase is corrected can further reduce the peak current than that in FIG. 7. as described above, not only the carrier wave frequency but also the carrier wave phase is corrected, so that the effect of reducing the peak current can be further improved. Each angle shown above is an example.FIG. 9 shows an example in which the carrier wave frequency and the carrier wave phase are corrected when the phase difference between voltage and current is large, for example, when the phase difference is 50°. Also, when the phase difference between voltage and current is large, the carrier wave frequency is corrected accordingly, so that as in FIG. 8, the carrier wave frequency is raised in portions in the vicinity of the peak values of the current, i.e., in FIG. 9 : 70° regions (from 80° to 150° and from 260° to 330°) around the peak value, and the carrier wave frequency is lowered in the remaining regions.The carrier wave phase is also corrected so that the PWM pulses in a low state in a certain portion (in the present embodiment, a range of some degrees in the vicinity of 130°) are near a positive peak of the current, and so that the PWM pulses in a high state in a certain portion (in the present embodiment, a range of some degrees in the vicinity of 310°) are near a negative peak of the current, so that the effect of reducing the peak current is improved. Each angle shown above is an example.In FIGS. 7, 8, and 9, the carrier wave frequency is corrected at a time point from its upper or lower peak, but the carrier wave frequency may be corrected at other times as well. In addition, since the correction values for the carrier wave frequency and the phase are examples, values different from those indicated in FIGS. 7, 8, and 9 may also be set.In FIGS. 7 and 8, the PWM pulse waveform of 0° to 180° in a voltage phase and the PWM pulse waveform of 180° to 360° in a voltage phase are offset point-symmetrically so that occurrence of even-order harmonics is suppressed, and the voltage pulses of 0° to 90° and the voltage pulses of 90° to 180°, and the voltage pulses of 180° to 270° and the voltage pulses of 270° to 360° are line-symmetrically set so that a waveform is expressed with a sine wave.In FIG. 9, the PWM pulse waveform from 0° to 180° in a voltage phase and the PWM pulse waveform from 180° to 360° in a voltage phase are designed to be point-symmetric, but the carrier wave frequency and the phase may also be corrected to not maintain symmetry.In FIGS. 7, 8, and 9, the correction value for the carrier wave frequency is a second-order component in one period of the electrical angle, but it may also be set as a third-order component or the like so that the carrier waveforms are identical between three phases.Although the invention has been described above in terms of exemplary embodiments, it is understood that the various features, aspects, and functionalities described in one embodiment are not limited in applicability to the particular embodiment with which they are described, but instead may be applied to embodiments of the invention, alone or in various combinations.It is therefore to be understood that numerous modifications may be utilized that are not described by way of example without departing from the scope of the present invention. For example, at least one of the components may be modified, added, or omitted.List of reference characters1 Rotating machine controller 2 Processor 3 Storage device 10 Voltage command generator 11 Carrier wave generation unit 12 Comparator 13 DC power supply 14 Inverter 15 Current detector 16 Rotating machine 20 Carrier wave corrector 21 Carrier wave frequency correction value calculator 22 Carrier wave phase correction value calculator 23 Correction determiner 24, 25 Multiplier 30 Carrier wave calculator 31, 32 Multiplier 33 Adder 34 Carrier wave generatorReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2-168 895 A

[0005] JP 2012-235 619 A

[0005]

Claims

A rotating machine control device for applying an AC voltage of a DC voltage from a DC power supply to a rotating machine through a converter, the rotating machine control device comprising: a voltage command generator that generates a voltage command value; a carrier wave generation unit that generates a carrier wave; and a comparator that determines a switching operation of the converter using the voltage command value and the output of the carrier wave generation unit, wherein the carrier wave generation unit comprises a carrier wave corrector that corrects a frequency of a carrier wave as a reference, and with respect to the frequency of the carrier wave as a reference, the carrier wave corrector performs correction so that the frequency of the carrier wave is raised by a factor of more than 1.0, Namely, at least in a part of a range where the magnitude of a current value in current information about the rotating machine is more than a predetermined magnitude and makes correction so that the frequency of the carrier wave is lowered by a factor of 1.0 or less, at least in a part of a range where the magnitude of the current value in current information about the rotating machine is less than the predetermined magnitude, or the carrier wave corrector makes correction so that the frequency of the carrier wave is raised by a factor of 1.0 or more, at least in a part of the range where the magnitude of the current value in current information about the rotating machine is more than a predetermined magnitude and makes correction so that the frequency of the carrier wave is lowered by a factor of less than 1.0, at least a part of the range where the magnitude of the current value in the current information about the rotating machine is less than the predetermined magnitude.A rotating machine control device for applying an AC voltage of a DC voltage from a DC power supply to a rotating machine through a converter, the rotating machine control device comprising: a voltage command generator that generates a voltage command value; a carrier wave generation unit that generates a carrier wave; and a comparator that determines a switching operation of the converter using the voltage command value and the output of the carrier wave generation unit, wherein the carrier wave generation unit comprises a carrier wave corrector that corrects a frequency of a carrier wave as a reference, and, with respect to the frequency of the carrier wave as a reference, the carrier wave corrector performs correction so that the frequency of the carrier wave is raised by a factor of more than 1.0, Namely, at least in a part of a range where the strength of a voltage command value for the rotating machine is more than a predetermined strength, and performs correction so that the frequency of the carrier wave is lowered by a factor of 1.0 or less, at least in a part of a range where the strength of the voltage command value for the rotating machine is less than the predetermined strength, or the carrier wave corrector performs correction so that the frequency of the carrier wave is raised by a factor of 1.0 or more, at least in a part of the range where the strength of the voltage command value for the rotating machine is more than a predetermined strength, and performs correction so that the frequency of the carrier wave is lowered by a factor of less than 1.0, at least in a part of the range, where the strength of the voltage command value for the rotating machine is less than the predetermined strength.The rotating machine control device according to claim 1 or 2, wherein the carrier wave corrector corrects the frequency of the carrier wave such that the number of times of the switching operation is constant in one period of the electrical angle or is not subjected to at least a change of 20% or more compared to the number of times of the switching operation before the correction.The rotating machine control device according to any one of claims 1 to 3, wherein the carrier shaft corrector corrects the phase of the carrier shaft so as to change the phase difference between the voltage command value and the carrier shaft, on the basis of one or more of at least the rotational speed of the rotating machine, a torque command, the voltage command value, and the current information about the rotating machine.The rotating machine control device according to any one of claims 1 to 4, wherein the carrier shaft corrector includes a correction determiner that determines whether or not to correct the frequency and the phase of the carrier shaft, and the correction determiner determines whether or not to perform the correction on the basis of one or more of at least the rotating speed of the rotating machine, the torque command, the voltage command value, and the current information about the rotating machine.The rotating machine control device according to any one of claims 1 to 5, wherein the carrier wave generation unit includes a carrier wave calculator, and the carrier wave calculator calculates the carrier wave on the basis of: the carrier wave frequency as a reference calculated from the rotational speed of the rotating machine and the number of pulses determined on the basis of the rotational speed and which is the product of a coefficient and the frequency of the voltage command value; and a correction value from the carrier wave corrector.The rotating machine control device according to any one of claims 1 to 6, wherein as current information about the rotating machine, a current detection value detected by a current detector, a current command value, or a current estimation value estimated or predicted from characteristics of the rotating machine is used.The rotating machine control device according to claim 1 or 2, wherein the range where the intensity is more than the predetermined intensity is a range from -20° to +20° in the vicinity of a peak value of the AC current flowing in the rotating machine.The rotating machine control device according to claim 1 or 2, wherein the range where the strength is more than the predetermined strength is a range in a 70° range around a peak value of the AC current flowing in the rotating machine when the phase difference between the voltage command value and current information is more than 50°.

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