Control device for a rotating machine

Abstract

A control device (1) for a rotating machine includes a switching command generation unit (2) for exchanging a DC voltage for AC voltages by means of an electrical converter (3) for applying these to a rotating machine (5), and also for commanding switching operations of PWM pulses in the electrical converter (3). The switching command generation unit (2) includes a command voltage generator (7) for generating a command voltage and a command voltage compensator (8) for compensating the aforementioned command voltage by means of the command voltage generator (7); and the command voltage compensator (8) compensates the aforementioned command voltage based on current-related information from the rotating machine (5), so that the current-related information does not exceed a predefined threshold value.

Description

Technical area

[0001] The invention of the present application relates to a control device for a rotating machine. State of the art

[0002] In a rotating machine control device or device, it is commonly known to use pulse-width modulation (PWM) technology, which uses the switching operations of an electrical power converter to apply a desired alternating current (AC voltage(s)) to a rotating machine. Since losses are generated in the switching operations described above, accompanying the switching events, it is desirable to reduce the number of switching events as much as possible.

[0003] However, if the number of switching events is reduced, there is a problem of causing an increase in voltage harmonics and an increase in current harmonics, and a problem of resulting increase in the peak value of the phase electric current (hereinafter also referred to as a "peak electric current"). If the peak electric currents increase, there is a fear that demagnetization or breakdown of the device may be caused, and therefore, it is desirable to ensure a reduction in the number of switching events and a reduction in peak electric currents while maintaining compatibility with each other.

[0004] As a configuration in which the increase of the peak electric currents is restrained, there is a configuration in which superposition of the sixth components (the fifth and seventh components in fixed coordinates) is performed on the electric current commands, and the electric currents are controlled so that those waveforms of the phase electric currents assume trapezoidal shapes (see, for example, Patent Document 1). State-of-the-art documentsPatent document

[0005] Patent Document 1: Japanese Patent JP 6 455 295 B2 Non-patent document

[0006] Non-Patent Document 1: Sugimoto et al., “Actualities of Theory and Design of AC Servo Systems” (sixth edition), Sogo Denshi Shuppan-Sha, August 2002, pp. 72–98 Summary of the inventionProblems to be solved by the invention

[0007] However, in a case where the number of switching events is reduced by the configuration according to Patent Document 1, it is not possible to appropriately control the harmonic currents (the sixth components), so there is a case where it results in the peak electric currents being increased, depending on the harmonic currents and their phases. Furthermore, in the configuration according to Patent Document 1, a PWM pulse (the pulse that has undergone pulse width modulation) cannot be manipulated immediately in the worst case, even if a peak electric current soon exceeds a predetermined value; thus, there is a problem that the peak electric current cannot be handled when it suddenly increases.

[0008] For example, in a case of FA (Factory Automation) in which the control device is used for a rotating machine, or in a case of an application such as an air conditioner, a machine tool, an aircraft, a railway vehicle or a railway track, an automobile vehicle and / or the like, a peak electric current suddenly increases so that the increase causes demagnetization of an electric power converter or the like and / or failure of its devices.

[0009] The present invention in this application is directed to disclosing technologies for solving the problems described above. Therefore, it is an object of the invention to reliably dampen the increase in the peak electric current flowing through a rotating machine and to protect the rotating machine and an electric power converter therefor when the number of switching events of the electric power converter is reduced and / or even when a harmonic current cannot be controlled to a desired value. Ways to solve the problems

[0010] In the rotating machine control device or apparatus disclosed according to the invention of the present application, which is a rotating machine control device comprising an electric power converter for converting a DC voltage into an AC voltage and for applying the AC voltage to a rotating machine, and comprising an electric current detector for detecting the electric current to be energized to the rotating machine, the rotating machine control device for controlling the rotating machine comprises: a switching command generating unit for generating a command voltage based on an operation-related command input from outside the switching command generating unit, and for outputting a switching command to the outside, according to the command voltage therefor, to the electric power converter, wherein the switching command generation unit comprises a command voltage generator for generating the command voltage and a command voltage compensator for compensating the command voltage generated by the command voltage generator; and the command voltage compensator compensates the command voltage so that current-related information including the value of the electrical detection current by the electrical current detector does not exceed a predetermined threshold value. Effects of the invention

[0011] In the control device for a rotating machine disclosed according to the invention of the present application, it is possible to reliably dampen the increase in the peak electric current flowing through a rotating machine and protect the rotating machine and the electric power converter therefrom when the number of switching events of the electric power converter is reduced and / or even when a harmonic current cannot be controlled to a desired value(s). Short description of the drawings Fig. 1 is a schematic diagram illustrating, by way of example, a control device for a rotating machine according to Embodiment 1; Fig. 2 is a block diagram for explaining the internal configuration of a switching command generating unit in the rotating machine control device according to Embodiment 1; Fig. 3 is a block diagram for explaining the internal configuration of a command voltage compensator in the rotating machine control device according to Embodiment 1; Fig. 4 is a block diagram for explaining the internal configuration of a hysteresis comparator in the rotating machine control device according to Embodiment 1; Fig. 5 is a block diagram for explaining the internal configuration of an allowable width setting unit in the rotating machine control device according to Embodiment 1; Fig. 6 is a diagram showing an operation example in a case where the compensation of a command voltage is not performed in the rotating machine control device according to Embodiment 1; Fig. 7 is a diagram showing an operation example in a case where the compensation of a command voltage is carried out in the rotating machine control device according to Embodiment 1; Fig. 8 is a diagram showing an operation example in a case where the compensation of a command voltage is not performed in the rotating machine control device according to Embodiment 1; Fig. 9 is a diagram showing an operation example in a case where the compensation of a command voltage is carried out in the rotating machine control device according to Embodiment 1; Fig. 10 is a diagram showing an operation example in a case where the compensation of a command voltage is not performed in the control device for a rotating machine according to Embodiment 1, and further the values ​​of the allowable widths are changed; and Fig. 11 is a hardware configuration diagram of the switching command generation unit in the rotating machine control device according to Embodiment 1. Embodiments for carrying out the inventionEmbodiment 1

[0012] Hereinafter, a detailed description will be given with reference to the drawings of a control device or apparatus of a rotating machine according to Embodiment 1 in the present invention of the present application.

[0013] Fig. 1 is a schematic diagram of a rotating machine control device according to Embodiment 1. The rotating machine control device 1 includes: a switching command generation unit 2; an electric power converter 3 to which a direct current (DC voltage from a DC power source 4) is applied, and with which AC voltages subjected to electrical energy conversion are applied to a rotating machine 5; and an electric power detector 6 for detecting an alternating current (AC current) output from the electric power converter 3.

[0014] The switching command generation unit 2 generates a reduction command voltage in the form of a pulse (hereinafter also referred to as a “voltage command”) based on a torque command or an operation-related command such as a command speed, an electric current command, or the like, and on the basis of an AC electric current, so that a switching command is output to the outside of the electric power converter 3.

[0015] The electric power converter 3 has switching devices 31, which form, for example, a full-bridge circuit, and is connected to the DC power source 4 and the rotating machine 5 by wiring. The electric power converter generates AC voltages from the DC voltage of the DC power source 4 according to a switching command(s) issued by the switching command generation unit 2 and applies the AC voltages to the rotating machine 5.

[0016] Note that, as the rotational speed approaches "0," the above-mentioned AC electric current and AC voltage become direct current (DC) and DC voltage, and, when an offset component is included, the above-mentioned AC electric current and AC voltage not only have an AC component but also naturally have a DC component. The electric current detector 6 detects electric currents iu, iv, and iw in each of the phases (U phase, V phase, and W phase) of the rotating machine 5, respectively.

[0017] As for the electric current detector 6, a predefined electric current command value may be used as a substitution for a part of the respective phases or all of the phases. Furthermore, an estimated electric current value obtained from characteristics of the rotating machine as specified in Expression (1) by an electric current estimator for predicting or estimating the electric current may be used as a substitution. Furthermore, a configuration in which the electric current is detected on a DC bus bar side and the electric current of each phase is calculated may be used as a substitution.

[0018] There is also a case where the electric current estimator can be used instead of an electric current sensor(s) to reduce costs. However, in a case where the accuracy or response of an electric current sensor is low, it is possible to reliably observe the electric current that changes transiently by using the electric current estimator as a replacement.

[0019] According to this arrangement, in a case where there is no electric current sensor and / or even in a case where the response of an electric current sensor is low, it is possible to reliably protect a rotating machine and / or an electric power converter. [Expression 1] [vuvvvw]=[R+sLusMuvsMwusMuvR+sLvsMvwsMwusMvwR+sLw][iuiviw]+ωreϕmag[−sinθre−sin(θre−23π)−sin(θre−43π)]

[0020] Here, expression (1) gives voltage equations on the fixed coordinates (uvw coordinates) of a rotating machine. Where: The symbols "Vu, Vv and Vw" respectively denote phase voltages; the symbol "R" denotes the winding resistance; the symbol "s" denotes the differential operator; the symbols "Lu, Lv and Lw" respectively denote the self-inductances of each winding; the symbols "Muv, Mwu and Mvw" respectively denote the mutual inductance between the respective windings; the symbols "iu, iv and iw" respectively denote the electrical phase currents; the symbol "ω re “ denotes the electrical angular velocity; the symbol “ϕ mag “ denotes the magnetic flux of the permanent magnet; and the symbol “θ re “ denotes the electrical angular position.

[0021] As for the rotating machine 5, a three-phase synchronous motor or a three-phase induction motor is assumed; however, the rotating machine may also be constituted, for example, by a three-phase double- or dual-winding motor or a motor other than a three-phase motor, such as a five-phase motor or a field-winding type motor; or the rotating machine may be constituted by another synchronous motor, such as a reluctance type synchronous motor or a switched reluctance type motor, or it may also be constituted by a motor other than the induction motor.

[0022] Next comes the description of Fig. 2. Fig. 2 is a block diagram for explaining the internal configuration of the switching command generation unit 2 according to Embodiment 1. The switching command generation unit 2 is composed of a command voltage generator 7 and a command voltage compensator 8.

[0023] The command voltage generator 7 generates an AC voltage command based on an operation-related command and an AC electric current by means of a publicly known scheme (see Non-Patent Document 1).

[0024] A configuration may be suitably used in which the AC voltage command is implemented such that the operation-related command is converted into an electric current command and an electric current vector is controlled on rotational coordinates (on the dq coordinates) so that the above-mentioned AC electric current follows the above-mentioned electric current command; or another configuration under constant V / f ratio control in which a three-phase voltage command is detected according to a command rotational speed may also be used.

[0025] In addition, although not specifically shown in the drawing, the position information of the rotor is detected at a time when the electric current vector control is performed by means of a position sensor such as a rotary encoder (resolver and / or encoder) and / or by means of a position estimator serving as a replacement for the position sensor, so that an AC voltage command is generated.

[0026] After the AC voltage command is generated, PWM pulses are generated to command the switching operations of the electric power converter 3. The PWM pulses are generated such that at least the fundamental wave components of the PWM pulses and the fundamental wave components of the AC voltage commands coincide with each other; and generally, the PWM pulses are calculated by comparing a triangular wave carrier with the AC voltage commands.

[0027] The triangular wave carrier is formed from a synchronous carrier (synchronous PWM) that is synchronous with the voltage phase or the speed, or it is formed from an asynchronous carrier (asynchronous PWM) that is not synchronous with the voltage phase or the speed.

[0028] As other schemes, not only as a comparison with the triangular wave carrier, the PWM pulses can also be calculated by means of a direct torque control and / or by means of an optimal pulse pattern scheme, a low-order harmonic elimination scheme, a position vector modulation scheme, a hysteresis comparator scheme and the like.

[0029] However, although the PWM pulses are calculated by any of the schemes described above, a tendency can be observed that voltage harmonics and electric current harmonics are reduced when the number of PWM pulses per an intermediate period in the electrical angle is large, and that the voltage harmonics and electric current harmonics are increased when the number of these PWM pulses is small.

[0030] Increasing the voltage and current harmonics will result in an increase in the peak electric current. If the peak electric current exceeds the upper current limit, there is a possibility of causing demagnetization and / or equipment failure. Consequently, control should be implemented so that the peak electric current flowing through a rotating machine never exceeds the upper current limit, if possible.

[0031] When considering switching losses, switching losses increase when the number of PWM pulses per intervening period in the electrical angle is large, whereas switching losses decrease when the number of these PWM pulses is small. And, in a case where switching losses increase, heat generation and efficiency decrease.

[0032] According to the above, the voltage harmonics and electric current harmonics and the switching losses show the relationship of trade-off between them, and consequently, it is generally desirable that the number of switching events be reduced so that a peak electric current does not exceed the upper limit of the electric current.

[0033] The command voltage compensator 8 corrects or compensates a PWM pulse according to a PWM pulse generated by the command voltage generator 7 and a detection electric current detected by the electric current detector 6; and the command voltage compensator generates a switching command input to the electric power converter 3.

[0034] Fig. 3 is a block diagram for explaining the internal configuration of the command voltage compensator 8 according to the rotating machine control device of Embodiment 1. The command voltage compensator 8 includes a switching occurrence number calculator 9, a hysteresis comparator 10, an allowable width setting means 11, a correction or compensation determiner 12, and a correction or compensation processing means 13.

[0035] The switching event number calculator 9 calculates the number of switching events based on switching commands generated by the compensation processing device 13 and inputs the number of switching events to the allowable width setting device 11.

[0036] The hysteresis comparator 10 makes a determination as to whether or not a PWM pulse generated by the command voltage generator 7 should be compensated based on the value of a detection electric current detected by the electric current detector 6 and on the basis of inverting and non-inverting threshold values ​​output from the allowable width setting means 11, and outputs a correction flag or compensation flag.

[0037] More specifically, an inverting threshold and a non-inverting threshold are specified with respect to the positive side of the AC electric current and its negative side, as shown in Fig. 4; when the amplitude of the AC electric current becomes larger than an inverting threshold (also referred to as a "first threshold"), a compensation flag is output, so that a PWM pulse (its positive or negative polarity) generated by the command voltage generator 7 is inverted (hereinafter: inverting processing).

[0038] The operations of inverting the PWM pulse(s) continue according to the compensation flag, and when the amplitude of the AC electric current becomes smaller than a non-inverting threshold (also referred to as a "second threshold"), the PWM pulse is not inverted (non-inverting); namely, the compensation flag is output so that the PWM pulse generated by the command voltage generator 7 is output as it is (hereinafter: non-inverting processing).

[0039] This means that the characteristics are used in which the phase electric current changes in the direction of the polarity of the PWM pulse (when the PWM pulse has a high level (Hi), the phase electric current increases in the positive direction; whereas when the PWM pulse has a low level (Low), the phase electric current increases in the negative direction), which means that in a case where a peak electric current is predicted and / or estimated so that the peak electric current exceeds an upper limit of the electric current, a PWM pulse is inverted so that the peak electric current is reduced.

[0040] With such a configuration, it is possible to manipulate a PWM pulse instantaneously even when the peak electric current is about to exceed a predetermined value; and consequently, control can be performed so that the peak electric current reliably does not exceed an upper limit of the electric current.

[0041] In addition, the PWM pulse is compensated in the configuration described above, so that it is possible to attenuate the increase of only a peak electric current that changes transiently without exerting a strong influence on the fundamental wave component of the command voltage generated by the command voltage generator 7 (it is not necessary to change the command to reduce the output).

[0042] Here, the case is mentioned in which, as an example, the peak value of the detection electric current exceeds a threshold value; however, it can also be mentioned in which, other than the peak value of the detection electric current, a targeted element focuses on the voltage and / or the electric current including their harmonics, the losses, the electric power, the torque, the number of revolutions, the position of the rotor, the temperature or the like (for example, the amplitude of a specific harmonic voltage, that of the electric current and / or the like; and the sum of these amplitudes or the like).

[0043] As explained above, the control device for a rotating machine according to Embodiment 1 is capable of controlling a switching command to compensate so that the peak value of the electric current flowing through a rotating machine does not exceed a predetermined threshold, and thus the rotating machine and / or an electric power converter can be reliably protected.

[0044] The allowable width setting device 11 makes a determination regarding inverting and non-inverting thresholds based on the number of switching events of the switching event number calculator 9 and on the basis of an upper limit of the number of compensation events, which is a counted number of compensating switching commands, and outputs the inverting and non-inverting thresholds to the hysteresis comparator 10.

[0045] As for the permissible or allowable width, it indicates the difference between a non-inverting threshold and an inverting threshold. The inverting threshold is set to a value such that a peak electrical current reliably does not exceed the upper limit of the electrical current during a period from the detection of the electrical current to a voltage output.

[0046] The non-inverting threshold is set to a value at which a PWM pulse compensated during inverting processing is not separated from a PWM pulse generated by the command voltage generator 7 to a large extent, and is also set to a value at which the number of switching events does not become excessively large as the number of inverting processing events increases excessively.

[0047] Specifically, if the difference between an inverting threshold and a non-inverting threshold (a permissible width therebetween) is made excessively large, this will result in a voltage command being generated that is separated from a PWM pulse generated by the command voltage generator 7, to a large extent, so that the control is not stabilized. On the other hand, if the permissible width is made excessively small, the "inverting" and "non-inverting" will be repeated more often than necessary, thus increasing switching losses more than necessary.

[0048] To deal with this, as in Fig. 5, an inverting threshold and a non-inverting threshold are preset so that a peak electric current reliably does not exceed an upper limit of the electric current, and also so that their values ​​are not significantly disturbed by a PWM pulse generated by the command voltage generator 7. Only in a case where the number of switching events becomes greater than necessary are the inverting threshold and the non-inverting threshold changed, and consequently, they are preset so that the allowable width between them becomes larger.

[0049] When the allowable width is made larger, inverting and / or non-inverting thresholds show difficulty in reaching them, and consequently it is possible to reduce the number of compensation events.

[0050] Regarding the inverting threshold and the non-inverting threshold, it is described that they are changed according to the number of switching events; however, it is also possible to change their values ​​not only according to the number of such switching events, but also according to one or more of situations among the number of revolutions, the electric current, the voltage, the torque, the position of the rotor, the temperature of the rotating machine, and the temperature of the electric power converter.

[0051] According to this arrangement, even in any of the situations (in a case where the influence due to heat is particularly large), it becomes possible to reliably and appropriately protect the rotating machine and the electric power converter.

[0052] By manipulating the allowable width, the following operations can also be performed. If the allowable width is set—whether intentionally or not—so as not to be larger than the required one, it becomes possible to increase the modulation factor of an AC voltage command generated by the command voltage generator 7. In this situation, if the amplitude of the AC voltage command can be made larger than that of a triangular wave carrier at the time a PWM pulse is generated, it is possible to implement an overmodulation drive, so that the frequency of such switching events can be reduced.

[0053] Overmodulation drive is a technology generally used to increase the utilization factor of an electric power converter's output; however, in a current configuration, overmodulation drive can be used to reduce the number of switching events. It should be understood that even when overmodulation drive is implemented, a phase electric current is controlled near its peak value by means of the hysteresis comparator 10 so that the phase electric current does not reach the upper current limit. Consequently, overmodulation drive can be implemented while maintaining the advantage of preventing the peak electric current from increasing more than necessary.

[0054] The compensation determiner 12 makes a determination regarding the presence or absence of compensation on a PWM pulse based on a compensation flag of the hysteresis comparator 10 and an upper limit of the number of compensation events, and outputs a compensation pulse.

[0055] The upper limit of the number of compensation events is an upper limit in which an upper limit of the number of compensation events during an intermediate period of the control period is defined, so that the upper limit is effective in preventing the increase in the number of switching events to a large extent.

[0056] In a case where the number of compensation events during an intermediate period of the control period does not reach an upper limit of the number of such compensation events according to a compensation flag, a compensation pulse is output so that compensation is permitted; whereas in a case where the number of compensation events exceeds an upper limit according to a compensation flag, there is a possibility that a peak electric current exceeds the upper limit of the electric current or that the number of switching events is excessively increased, and thus a change is caused so that the operations are stopped or so that the allowable width of the allowable width setting means 11 is set to an appropriate value.As described above, according to the rotating machine control device of Embodiment 1, it is possible to achieve the detection of an abnormal state.

[0057] The compensation processing means 13 generates a switching command by using a PWM pulse generated by the command voltage generator 7 and a compensation pulse generated by the compensation determiner 12, and outputs the switching command to the electric power converter 3.

[0058] As explained above, when the hysteresis characteristics are used with the presence or absence of compensation of a switching command, it is possible to prevent the occurrence of an event in which the number of switching compensation events is excessively increased.

[0059] Next, an explanation will be given of the operating or working effects by the control device 1 for a rotating machine.

[0060] Fig. 6A and Fig. 6B are diagrams each showing a result that an AC electric current waveform is enlarged in a case where such a command voltage compensator 8 was not provided, according to conventional PWM pulses. Fig. 6A shows electrical current characteristics, and Fig. 6B shows voltage characteristics (which are also shown in Fig. 7A to Fig. 10A and Fig. 7B to Fig. 10B are applicable, in a similar manner as described below).

[0061] In addition, Fig. 6B, the characteristics of a switching command are shown with the solid line; the characteristics of a modulation signal are shown with the broken lines; and the characteristics of a triangular wave carrier are shown with the alternating long and short dashed lines (which are similarly shown on Fig. 7B to Fig. 10B are applicable, as explained below).

[0062] As particularly in Fig. 6B, the following applies: When the number of switching events is small, a peak electrical current of the AC electrical current waveform will result in an exceedance of an upper limit of the electrical current (see the circular area shown in Fig. 6A is surrounded by the broken lines).

[0063] Fig. 7A and Fig. 7B are diagrams each showing a result in which an AC electric current waveform is enlarged, in a case where the command voltage compensator 8 was present and a PWM pulse was corrected or compensated. In the case shown above, a peak value of the AC electric current does not occur to reach an upper limit of the electric current; however, since the electric current increases and tends toward its upper limit, and since the increase, if continued as it does, the electric current could eventually exceed an inverting threshold value, which is a value smaller than the upper limit of the above-mentioned electric current (see Fig. 7A).

[0064] If the inverting threshold is exceeded, a PWM pulse is compensated by the command voltage compensator 8, so that a switching command is reversed or inverted (see Fig. 7B); and consequently, the peak electric current does not occur to reach the upper limit of the current (see Fig. 7A).

[0065] In addition, at a time when an AC electric current becomes smaller than a non-inverting threshold during the inverting processing, the inverting processing is released, and a PWM pulse is output from the command voltage generator 7, and thus stable control operations are enabled.

[0066] That is, a pulse waveform (switching signal(s)) is directly manipulated, and consequently the peak electrical current is protected with greater reliability.

[0067] Fig. 8A and Fig. 8B each indicate the processes in a case where the number of switching events is increased. In Fig. 8A - similar to the Fig. 6A - and also in Fig. 8B -similar to the Fig. 6B - explicitly shows a result of an electrical AC current waveform according to conventional PWM pulses; whereas in the Fig. 9A - similar to the Fig. 7A - and also in the Fig. 9B - similar to the Fig. 7B - a result is shown in which the PWM pulses have been corrected or compensated by means of the command voltage compensator 8, and in which the control has been performed so that a peak electric current has not reached the upper limit of the electric current.

[0068] As in Fig. As shown in Figure 9A, control is performed so that the peak electric current does not reach an upper limit; however, as described above, it is feared that the number of switching events will be excessively increased by correcting or compensating a PWM pulse. By setting the allowable or permissible widths larger than those in the case described in Fig. 9A and Fig. 9B, an overmodulation drive can be implemented so that it becomes possible to maintain a situation where a peak electric current does not reach an upper limit of the electric current and also to reduce the number of switching events (see Fig. 10A and Fig. 10B). This means that it is possible to prevent the increase in the number of switching events by means of the command voltage compensator.

[0069] According to the invention of the present application, it is described that a PWM pulse is compensated so that an electric current flowing through a rotating machine does not exceed an upper limit of the electric current, and thus, essentially, control is performed such that current-related information such as an electric current, an electric current command value, or an electric current estimate value does not exceed a threshold value; however, even in a case where the electric current inadvertently exceeds the threshold value (such as caused by a sampling error(s), a sensor error(s), and / or the like), similar effects can be achieved.Accordingly, the scope of implementation of the invention of the present application is not limited to the case where the electric current or the current-related information does not exceed a threshold value.

[0070] Furthermore, according to the above-described manner, it is described that a PWM pulse is directly compensated so that an electric current flowing through a rotating machine does not exceed an upper limit of the electric current; however, the configuration may also be used such that the amplitude of a command voltage for generating the PWM pulse and / or a phase of the command voltage therefor are compensated so that the PWM pulse is indirectly compensated.

[0071] More specifically, in a case where an electric current flowing through a rotating machine exceeds a first threshold, the amplitude of a command voltage and / or its phase are compensated so that the polarity of a PWM pulse is inverted; and, in a case where the electric current flowing through the rotating machine becomes smaller than a second threshold, a compensation amount of the amplitude of the command voltage and / or that of its phase is made smaller so that the polarity of the PWM pulse(s) is not inverted.

[0072] As another configuration, at a time when a PWM pulse is generated instead of the command voltage, the amplitude of a triangular wave carrier used and / or its phase are similarly compensated, and the PWM pulse is indirectly compensated, so that similar effects can be achieved even with such a configuration.

[0073] In addition, Fig. 11 illustrates an example of the hardware of the switching command generation unit 2 in the rotating machine control device 1 in the present invention of the present application. The switching command generation unit is composed of a processor 100 and a memory device 101; and the memory device 101 is provided with volatile storage means of a random access memory (RAM) or the like, and auxiliary non-volatile storage means of a flash memory or the like, which are not shown in the drawing. Furthermore, auxiliary storage means of a hard disk or the like may be provided instead of the flash memory.

[0074] Furthermore, in the invention of the present application, exemplary embodiments are described; however, the various features, aspects, and functions described in an embodiment are not necessarily limited to applications of a specific embodiment, but are applicable to an embodiment alone or in various combinations.

[0075] Therefore, unlimited modification examples not described by way of example can be used without departing from the scope of the technologies disclosed in the description of the present invention application. For example, there is a modification example included as a case where at least one component is modified or added to or omitted from a component of another embodiment. List of reference symbols 1 control device for a rotating machine 2 Switching command generation unit 3 electrical power converters 4 DC power source 5 rotating machine 6 Electric current detector 7 Command voltage generator 8 Command voltage compensator 9 Calculators for switching event count 10 Hysteresis comparator 11 Specification device for permissible width 12 compensation determiners 13 Compensation processing device 31 Switching device 100 processor and 101 Storage device. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6 455 295 B2

[0005] Cited non-patent literature

[0000] Sugimoto et al., “Actualities of Theory and Design of AC Servo Systems” (sixth edition), Sogo Denshi Shuppan-Sha, August, 2002, pp. 72-98

[0006]

Claims

[1] A control device for a rotating machine, comprising an electric power converter for converting a DC voltage into an AC voltage and for applying the AC voltage to a rotating machine, and comprising an electric current detector for detecting the electric current to be energised to the rotating machine, the control device for a rotating machine comprising the following for controlling the rotating machine: a switching command generating unit for generating a command voltage based on an operation-related command input from outside the switching command generating unit, and for outputting a switching command to the outside, according to the command voltage therefor, to the electric power converter, wherein the switching command generation unit comprises a command voltage generator for generating the command voltage and a command voltage compensator for compensating the command voltage generated by the command voltage generator; and wherein the command voltage compensator compensates the command voltage such that current-related information including the value of the electric detection current by the electric current detector does not exceed a predetermined threshold value. [2] A control device for a rotating machine according to claim 1, wherein the command voltage compensator operates to compensate the command voltage when the current-related information exceeds a first threshold value set in advance; and the command voltage compensator operates according to the operation by making a compensation amount in the command voltage smaller when the current-related information becomes smaller than a second threshold value set in advance. [3] A control device for a rotating machine according to claim 1 or 2, wherein the command voltage compensator is operated such that the polarity of a pulse width modulation pulse generated according to the command voltage is inverted when the current-related information exceeds a first threshold value set in advance; and the command voltage compensator is operated such that the polarity of a pulse width modulation pulse generated according to the command voltage is not inverted and the pulse width modulation pulse is output as it is when the current-related information becomes smaller than a second threshold value set in advance. [4] Control device for a rotating machine according to claim 2, wherein the command voltage compensator comprises a switching event count calculator for calculating a number of switching events; and wherein the command voltage compensator changes the first threshold and the second threshold such that the difference between the first threshold and the second threshold becomes larger when the number of switching events is larger than a threshold that is predetermined in advance. [5] A rotating machine control device according to any one of claims 2 to 4, wherein the first threshold value and the second threshold value are changed in values ​​according to one or more situations among a number of switching events, an electric current, a voltage, a torque, a position of a rotor, a temperature of the rotating machine, and a temperature of the electric power converter. [6] A control device for a rotating machine according to any one of claims 1 to 5, wherein the current-related information includes at least an electric current of the rotating machine, a value of a detection electric current detected by an electric current sensor, a command value for the electric current defined in advance, and a command value for the electric current estimated or predicted from a characteristic of the rotating machine. [7] Control device for a rotating machine according to one of claims 1 to 6, wherein the command voltage compensator comprises a compensation determiner for determining the presence or absence of compensation in the command voltage; and wherein the compensation determiner calculates a number of events for compensating the command voltage during an intermediate period predetermined in advance, an output of the compensation determiner is stopped when a number of events for compensating the command voltage exceeds an upper limit of a number of compensation events predetermined in advance.

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