PWM control device, and PWM control method

Abstract

To make it possible to detect abnormality of PWM CONTROL generated inside a PWM control device, while being able to detect abnormality even when a duty command is 0% or 100%.SOLUTION: A PWM control device 100 comprises output pulse width acquisition means 12 for acquiring an output pulse width Wact of a PWM control signal SW, command pulse width calculation means 13 for calculating a command pulse width Wref of a duty command Dref, and abnormality determination means 17 for determining presence / absence of abnormality of PWM control by comparing the output pulse width Wact with the command pulse width Wref. The output pulse width acquisition means 12 measures the output pulse width of the PWM control signal SW, and corrects a measured value of the output pulse width to make the corrected measured value of the output pulse width be the output pulse width Wact, when it is determined that there is no output pulse.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to a PWM control device and a PWM control method. [Background technology]

[0002] PWM (Pulse Width Modulation) control is widely used as a method for controlling a load device such as a flow control valve or a motor. In PWM control, a PWM control signal generated by a PWM control device is sent to a drive circuit, which generates a drive signal corresponding to the PWM control signal. The generated drive signal is sent to a load device, which is driven by the drive signal. In such PWM control, it is necessary to check whether there is an abnormality in the PWM control being executed. Here, as an abnormality detection device for a conventional control circuit, there is one that detects an abnormality by inputting a check pulse at a fixed period to an output transistor that controls the operation of the load, acquiring an inverted pulse of this check pulse, and comparing the pulse width of the check pulse with the pulse width of the inverted pulse (see, for example, Patent Document 1). There is also a method for detecting an abnormality in PWM control by successively comparing the level of a PWM control signal output from a PWM control device with the level of a drive signal output from a drive circuit (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 60-119480 Publication [Patent Document 2] Japanese Patent Application Publication No. 11-143530 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a technique similar to the anomaly detection device described in Patent Document 1 is applied to PWM control, when there is no apparent output pulse, such as when the duty command is 0% or 100%, it is not possible to obtain a pulse width for comparison and therefore not possible to detect an anomaly. Furthermore, in the method disclosed in Patent Document 2, which compares the level of the PWM control signal with the level of the drive signal, it is possible to detect an abnormality even when the duty command is 0% or 100%, but because the PWM control signal output from the PWM control device is used as the basis for abnormality detection, it is not possible to detect an abnormality within the PWM control device, and it is not possible to determine whether the PWM control signal is being output from the PWM control device in accordance with the duty command set by the PWM control device. The present application discloses technology for solving the above-mentioned problems, and aims to provide a PWM control device and a PWM control method that can detect abnormalities even when the duty command is 0% or 100%, and can detect PWM control abnormalities that occur within the PWM control device. [Means for solving the problem]

[0005] The PWM control device disclosed in the present application comprises a control command generating means for generating a PWM control command, a control signal generating means for generating a PWM control signal for controlling a controlled device based on the PWM control command, an output pulse width acquiring means for acquiring an output pulse width of the PWM control signal, a command pulse width calculating means for calculating a command pulse width which is the pulse width of the PWM control command, and an abnormality determining means for determining the presence or absence of an abnormality in the PWM control by comparing the output pulse width with the command pulse width, and the output pulse width acquiring means measures an output pulse width measurement value which is a measurement value of the width of the output pulse of the PWM control signal based on an edge of the PWM control signal, and when it is determined that there is no output pulse by determining the presence or absence of an output pulse of the PWM control signal, corrects the output pulse width measurement value and sets the corrected output pulse width measurement value as the output pulse width.

[0006] Another PWM control device disclosed in the present application is a PWM control device that outputs a PWM control signal to a controlled device having an electric motor that operates by being supplied with power according to the PWM control signal, and includes a control command generating means for generating a PWM control command, a control signal generating means for generating a PWM control command based on the PWM control command, at least one of an output pulse width acquiring means for acquiring an output pulse width of the PWM control command and a command pulse width calculating means for calculating a command pulse width which is the pulse width of the PWM control command, an abnormality determining means for determining whether or not there is an abnormality in the PWM control, and a rotation state acquiring means for acquiring the rotation state of the electric motor, and the abnormality determining means has a pulse width fixation time measuring unit for measuring a pulse width fixation time which is the time during which the output pulse width or the command pulse width continues to be a constant value, and determines whether or not there is an abnormality in the PWM control based on a comparison between the pulse width fixation time and the time determined based on the rotation state, and based on the presence or absence of a time fluctuation in the ideal value of the PWM control command.

[0007] Furthermore, the PWM control method disclosed in the present application includes a control command generating step of generating a PWM control command, a control signal generating step of generating a PWM control signal for controlling a controlled device based on the PWM control command, an output pulse width acquiring step of acquiring an output pulse width of the PWM control signal, a command pulse width calculating step of calculating a command pulse width which is the pulse width of the PWM control command, and an abnormality determination step of determining the presence or absence of an abnormality in the PWM control by comparing the output pulse width with the command pulse width. In the output pulse width acquiring step, an output pulse width measurement value which is a measurement value of the width of the output pulse of the PWM control signal is measured based on an edge of the PWM control signal, and when it is determined that there is no output pulse by determining the presence or absence of an output pulse of the PWM control signal, the output pulse width measurement value is corrected, and the corrected output pulse width measurement value is used as the output pulse width.

[0008] Another PWM control method disclosed in the present application is a PWM control method for outputting a PWM control signal to a controlled device having an electric motor that operates by being supplied with power according to the PWM control signal, and includes a control command generating step for generating a PWM control command, a control signal generating step for generating a PWM control command based on the PWM control command, at least one of an output pulse width acquiring step for acquiring an output pulse width of the PWM control command and a command pulse width calculating step for calculating a command pulse width which is the pulse width of the PWM control command, an abnormality determining step for determining whether or not there is an abnormality in the PWM control, and a rotation state acquiring step for acquiring the rotation state of the electric motor. In the abnormality determining step, a pulse width fixation time which is the time during which the output pulse width or the command pulse width continues to be a constant value is measured, and the presence or absence of an abnormality in the PWM control is determined based on the comparison between the pulse width fixation time and a time determined based on the rotation state, and on the presence or absence of a time fluctuation in the ideal value of the PWM control command. Effect of the Invention

[0009] According to the PWM control device or PWM control method disclosed in the present application, it is possible to detect an abnormality even when the duty command is 0% or 100%, and it is also possible to detect an abnormality in PWM control occurring within the PWM control device. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration of a PWM control device in accordance with a first embodiment. [Diagram 2] 2 is a block diagram showing a configuration of a control command generating means according to the first embodiment. FIG. [Diagram 3] 2 is a block diagram showing a configuration of an abnormality determination means according to the first embodiment. FIG. [Figure 4] 2 is a block diagram showing a configuration of an output pulse width acquiring means according to the first embodiment. FIG. [Diagram 5] FIG. 13 is a diagram showing the relationship between a PWM control signal and an output pulse width measurement value according to the first embodiment, and shows a case where the output pulse width measurement value is not corrected. [Figure 6A]FIG. 11 is a diagram showing the relationship between a PWM control signal and an output pulse width measurement value according to the first embodiment, and is a diagram showing a case where the output pulse width measurement value is corrected. [Figure 6B] 5 is a diagram illustrating a determination time for determining the absence of an output pulse in the first embodiment. FIG. [Figure 7] FIG. 2 is a diagram illustrating an example of a hardware configuration for implementing a control unit according to the first embodiment. [Figure 8] 4 is a flow chart showing the operation of the PWM control device in the first embodiment. [Figure 9] 4 is a flow diagram showing an output pulse width acquisition step according to the first embodiment. FIG. [Figure 10] FIG. 4 is a flow diagram showing an abnormality determination process according to the first embodiment. [Figure 11] FIG. 11 is a block diagram showing a configuration of a power conversion device according to a second embodiment. [Figure 12] FIG. 11 is a block diagram showing a configuration of a control unit according to the second embodiment. [Figure 13] FIG. 11 is a block diagram showing a configuration of a control command generating means according to the second embodiment. [Figure 14] FIG. 11 is a block diagram showing a configuration of a rotation state acquiring means according to the second embodiment. [Figure 15] FIG. 11 is a block diagram showing a configuration of an abnormality determination means according to the second embodiment. [Figure 16] FIG. 11 is a diagram comparing the time waveform of the electrical angle with the time waveform of the PWM control signal on the upper side of the U phase in the second embodiment. [Figure 17] 11 is a flowchart showing the operation of the PWM control device in the second embodiment. [Figure 18] FIG. 11 is a flow chart showing an abnormality determination process according to the second embodiment. [Figure 19] FIG. 11 is a block diagram showing a configuration of a control unit according to the third embodiment. [Figure 20] FIG. 11 is a block diagram showing a configuration of an abnormality determination means according to the third embodiment. [Figure 21] FIG. 11 is a flow chart showing the operation of the PWM control device in the third embodiment. [Figure 22] It is a flowchart showing the abnormality determination process according to Embodiment 3. [Figure 23] It is a block diagram showing the configuration of the abnormality determination means according to Embodiment 4. [Figure 24] It is a flowchart showing the abnormality determination process according to Embodiment 4.

Embodiments for Carrying Out the Invention

[0011] Embodiment 1. Hereinafter, the configuration and operation of the PWM control device according to Embodiment 1 of Embodiment 1 will be described with reference to FIGS. 1 to 10.

[0012] <Configuration of PWM Control Device> FIG. 1 is a block diagram showing the configuration of the PWM control device in Embodiment 1. The PWM control device 100 includes a control unit 10 and transmits the PWM control signal SW generated by the control unit 10 to the device under control 900. The device under control 900 is controlled according to the PWM control signal. The device under control 900 includes a drive circuit that generates a drive signal according to the PWM control signal and a load device such as an electric motor that operates by the drive signal, but the internal configuration of the device under control 900 is omitted in FIG. 1.

[0013] <Functional Blocks of Control Unit> The control unit 10 includes a control command generating means 11 which generates a duty command Dref as a PWM control command and outputs the duty command Dref to a command pulse width calculating means 13 and a control signal generating means 19, a control signal generating means 19 which generates a PWM control signal SW based on the duty command Dref and outputs the PWM control signal SW to the controlled device 900 and an output pulse width acquiring means 12, an output pulse width acquiring means 12 which acquires an output pulse width Wact, which is the pulse width of the PWM control signal SW, and outputs the output pulse width Wact to an abnormality determining means 17, a command pulse width calculating means 13 which calculates a command pulse width Wref based on the duty command Dref and outputs the command pulse width Wref to the abnormality determining means 17, and an abnormality determining means 17 which determines the presence or absence of an abnormality from a comparison result between the output pulse width Wact and the command pulse width Wref, and outputs the result as a state determination result ErrSt. The control unit 10 also includes an output stop instruction means 18 which receives the state determination result ErrSt from the abnormality determination means 17 and outputs a stop instruction signal Stp to the control signal generation means 19 in accordance with the state determination result ErrSt.

[0014] The control command generating means 11 will be described. Fig. 2 is a block diagram showing the configuration of the control command generating means according to the first embodiment. The control command generating means 11 has a duty command calculation unit 11a. The duty command calculation unit 11a calculates a duty command Dref for generating a PWM control signal SW based on a control command from a higher-level controller or a higher-level system (not shown), an input from a user, or feedback from the controlled device 900, and outputs the calculated duty command Dref.

[0015] The output pulse width acquisition means 12 will be described in detail later.

[0016] The command pulse width calculation means 13 calculates the desired pulse width of the PWM control signal SW. This "desired pulse width" is the command pulse width Wref, and the command pulse width calculation means 13 calculates the command pulse width Wref based on the duty command Dref.

[0017] The abnormality determination means 17 will be described. FIG. 3 is a block diagram showing the configuration of the abnormality determination means according to the first embodiment. The abnormality determination means 17 has a pulse width comparison unit 17a and a difference abnormality determination unit 17b. The command pulse width Wref and the output pulse width Wact are input to the pulse width comparison unit 17a. The pulse width comparison unit 17a compares the command pulse width Wref with the output pulse width Wact, calculates the difference WDiff between them, and outputs the difference WDiff to the difference abnormality determination unit 17b. The difference abnormality determination unit 17b determines whether the difference WDiff is equal to or greater than a threshold value Dth, and outputs a state determination result ErrSt based on the result. If the difference WDiff is equal to or greater than the threshold value Dth, the difference abnormality determination unit 17b determines that there is an abnormality in the PWM control, and sets the state determination result ErrSt to "abnormal". If the difference WDiff is less than the threshold value Dth, it determines that the PWM control is operating normally, and sets the state determination result ErrSt to "normal".

[0018] The output pulse width Wact is the pulse width of the PWM control signal SW output by the control signal generating means 19. The control signal generating means 19 transmits the generated PWM control signal SW to the output pulse width acquiring means 12 and the controlled device 900, respectively. Therefore, the PWM control signal SW received by the output pulse width acquiring means 12 does not pass through the inside of the controlled device 900, nor does it pass through the transmission path between the PWM control device 100 and the controlled device 900. Therefore, if there is a difference between the output pulse width Wact acquired by the output pulse width acquiring means 12 and the command pulse width Wref, the cause of this difference occurs within the PWM control device 100. Therefore, if the difference WDiff is large (greater than or equal to the threshold value Dth), it indicates that an abnormality has occurred within the PWM control device 100.

[0019] When determining whether or not there is an abnormality by comparing two "pulse widths" as in the abnormality determination means 17 of the first embodiment, there is no need to provide an additional dedicated circuit. However, when comparing two "signal levels" as in the technology described in Patent Document 2, additional hardware such as a dedicated circuit is required. Although it is possible to compare the signal levels using software without adding hardware, such a configuration has the problem of increasing the processing load of the arithmetic device. The abnormality determination means 17 of the first embodiment does not increase the processing load of the arithmetic device, and does not require the addition of a dedicated circuit or the like.

[0020] The output stop instruction means 18 stops the generation of the PWM control signal SW by the control signal generating means 19 according to the state of PWM control indicated by the state determination result ErrSt. The output stop instruction means 18 does nothing if the state determination result ErrSt is "normal", and outputs a stop instruction signal Stp to the control signal generating means 19 if the state determination result ErrSt is "abnormal". The control signal generating means 19 that has received the stop instruction signal Stp stops the generation and output of the PWM control signal SW.

[0021] The control signal generating means 19 generates and outputs a PWM control signal SW for controlling the controlled device 900 in response to the duty command Dref. The control signal generating means 19 also generates and outputs the PWM control signal SW, for example, with a PWM pulse period. The generation of the PWM control signal SW by the control signal generating means 19 is performed by comparing the duty command Dref with a carrier wave. More specifically, the PWM control signal SW is generated using, for example, a triangular wave comparison method in which a triangular wave having an isosceles triangle shape with equal rising and falling speeds is used as the carrier, or a sawtooth wave comparison method in which a sawtooth wave that periodically repeats linear increase and rapid drop is used as the carrier. As described above, when the stop instruction signal Stp is received from the output stop instruction means 18, the control signal generating means 19 stops generating and outputting the PWM control signal SW. The PWM pulse period may be determined in advance or may be set according to the state of the load device.

[0022] The following describes the output pulse width acquisition means 12. Fig. 4 is a block diagram showing the configuration of the output pulse width acquisition means according to the first embodiment. The output pulse width acquisition means 12 includes an output pulse edge detection unit 12a that notifies detection of the edge of the output pulse of the PWM control signal SW, an output pulse width measurement unit 12b that measures the output pulse width of the PWM control signal SW and outputs it to an output pulse width correction unit 12f as an output pulse width measurement value Wmon, an edge time acquisition unit 12c that acquires the time of the edge timing by a time counter and outputs it to a pulse presence / absence determination unit 12d as an edge time EdgT, a pulse presence / absence determination unit 12d that determines the presence or absence of an output pulse in the PWM pulse period and outputs the result as a pulse presence / absence determination result EdgR to the output pulse width correction unit 12f, a signal level acquisition unit 12e that acquires the signal level at the edge timing of the PWM control signal SW and outputs it to the output pulse width correction unit 12f as a signal level EdgLev, and an output pulse width correction unit 12f that corrects the output pulse width measurement value Wmon in accordance with the pulse presence / absence determination result EdgR or outputs it as the output pulse width Wact without correction.

[0023] The output pulse edge detection unit 12a receives the PWM control signal SW and detects the rising and falling edges (edges) of the output pulse of the PWM control signal SW. The output pulse edge detection unit 12a outputs the edge detection signal Edg at the timing (edge ​​timing) at which the edge of the PWM control signal SW is detected as described above. The edge detection signal Edg is input to the output pulse width measurement unit 12b, the edge time acquisition unit 12c, and the signal level acquisition unit 12e. In this manner, the output pulse edge detection unit 12a notifies the detection of the edge of the output pulse of the PWM control signal SW by outputting the edge detection signal Edg. The edge detection signal Edg is output at the edge timing, and the receiving side of the edge detection signal Edg receives the edge detection signal Edg at the edge timing.

[0024] The output pulse width measuring unit 12b receives the edge detection signal Edg, operates a counter at the edge timing of the PWM control signal SW, and measures the output pulse width of the PWM control signal SW from the count value from rising to falling. The output pulse width measuring unit 12b outputs the measured output pulse width as an output pulse width measurement value Wmon. Note that, although the output pulse width of the PWM control signal SW is measured from the count value from rising to falling in the first embodiment, the output pulse width of the PWM control signal SW may be measured from the count value from falling to rising.

[0025] When the control unit 10 is configured by, for example, a microcomputer, the output pulse edge detection unit 12a and the output pulse width measurement unit 12b can be realized by utilizing an input timer function of the microcomputer.

[0026] The edge time acquisition unit 12c receives the edge detection signal Edg, operates a time counter at the edge timing, and acquires the time of the edge timing. The edge time acquisition unit 12c outputs the acquired time as the edge time EdgT of the output pulse of the PWM control signal SW.

[0027] The pulse presence / absence determination unit 12d determines whether or not there is an output pulse of the PWM control signal SW based on the time elapsed since the last edge timing. More specifically, the pulse presence / absence determination unit 12d receives the edge time EdgT, and measures the time elapsed since the last edge timing, i.e., the last edge detection time, from the difference between the current time and the edge time EdgT. If the time elapsed since the last edge timing is equal to or longer than the PWM pulse period, the pulse presence / absence determination unit 12d determines that there is no output pulse. The pulse presence / absence determination unit 12d executes the above determination at the PWM pulse period. That is, the pulse presence / absence determination unit 12d determines the presence / absence of an output pulse for each PWM pulse period. The pulse presence / absence determination unit 12d outputs the result of the determination as a pulse presence / absence determination result EdgR.

[0028] The pulse presence / absence determining unit 12d may be operated at a period and timing different from the PWM pulse period. In this case, the period for determining the presence / absence of an output pulse (the period subject to determination) may be set to a value corresponding to the execution period and execution timing of the determination by the pulse presence / absence determining unit 12d. This allows the execution of determination by the pulse presence / absence determining unit 12d to be set without being limited to the PWM pulse period.

[0029] The signal level acquisition unit 12e receives the edge detection signal Edg, acquires the level of the PWM control signal SW at the edge timing as "high" or "low", and outputs the signal level EdgLev at the time of edge detection.

[0030] The output pulse width correction unit 12f receives the output pulse width measurement value Wmon, the pulse presence / absence determination result EdgR, and the signal level EdgLev at the time of edge detection. If it is determined that there is an output pulse (the pulse presence / absence determination result EdgR is "pulse present"), the output pulse width correction unit 12f does not correct the output pulse width measurement value Wmon and outputs it as it is as the output pulse width Wact. If it is determined that there is no output pulse (the pulse presence / absence determination result EdgR is "pulse absent"), the output pulse width correction unit 12f corrects the output pulse width measurement value Wmon and outputs it as the output pulse width Wact.

[0031] The output pulse width correction unit 12f corrects the output pulse width as follows: When the signal level EdgLev is "low", the output pulse width correction unit 12f corrects the output pulse width measurement value Wmon to zero and outputs the output pulse width Wact with "the value of the output pulse width Wact=0". When the signal level EdgLev is "high", the output pulse width correction unit 12f corrects the output pulse width measurement value Wmon to the same value as the PWM pulse period and outputs the output pulse width Wact with "the value of the output pulse width Wact=the PWM pulse period".

[0032] In addition, the signal level acquisition unit 12e in embodiment 1 acquires the level of the PWM control signal SW at the edge timing, but since the signal level EdgLev only needs to be acquired when the output pulse width is corrected, the signal level acquisition unit 12e may acquire the level of the PWM control signal SW when the output pulse width correction unit 12f performs the correction.

[0033] As described above, the PWM control device 100 in the first embodiment has two features in acquiring the output pulse width of the PWM control signal SW. The first feature is that the output pulse width is measured by detecting edges (rising and falling edges) of the output pulse of the PWM control signal SW in the output pulse width acquisition means 12, and the output pulse width measurement value Wmon is corrected when there is no output pulse of the PWM control signal SW.

[0034] The second is that, in correcting the output pulse width measurement value Wmon, the output pulse width measurement value Wmon is corrected to the PWM pulse period or zero depending on the level ("high" or "low") of the PWM control signal SW when the edge of the PWM control signal SW is detected (edge ​​timing). As a result, when there is no output pulse of the PWM control signal SW, the output pulse width Wact also becomes the PWM pulse period or zero depending on the level of the PWM control signal SW when the edge is detected.

[0035] The above-described operations from edge detection to correction of the output pulse width measurement value Wmon can be performed in the same manner as the operations performed in normal PWM control, i.e., there is no need to provide an additional dedicated circuit to realize the output pulse width acquisition means 12.

[0036] <Explanation of the effect of correcting the output pulse width measurement value> Correction of the output pulse width measurement value Wmon by the output pulse width correction unit 12f will be described in detail. First, as a comparative example, a case where no correction is performed will be described with reference to FIG. 5. In FIG. 5, the horizontal axis of the graph indicates time. The vertical axis of the upper graph indicates the level of the PWM control signal SW and the PWM generating triangular wave (carrier). The PWM control signal SW is "high" when it is "1" and "low" when it is "0". The vertical axis of the lower graph indicates the output pulse width measurement value Wmon.

[0037] In the first embodiment, the output pulse width measurement value Wmon is updated at the timing when the PWM generating triangular wave becomes a valley, and is updated to the final output pulse width at that time. For example, since the output pulse width is T1 around time 0.0164, the output pulse width measurement value Wmon is updated to T1 at time 0.0165 seconds. Also, since the output pulse width of the output pulse that falls at time 0.0166 seconds is T2, the output pulse width measurement value Wmon is updated to T2 at time 0.0167 seconds.

[0038] However, when there is no output pulse, such as in the area A surrounded by the dashed line in FIG. 5, the output pulse width measurement value Wmon is not updated. This means that when the duty command Dref is 0% or 100%, the edge of the output pulse is not detected and the output pulse width measurement value Wmon is not updated. When the output pulse width measurement value Wmon is not updated, the correct current output pulse width Wact cannot be obtained, and therefore, abnormality determination by comparing the command pulse width Wref and the output pulse width Wact cannot be performed correctly. This is also true when the output pulse width is converted into a duty output. In other words, when the output pulse width measurement value Wmon is not updated even though the duty command Dref is 0% or 100%, a difference occurs between the duty command and the duty output even though the PWM control is normal, and abnormality cannot be detected appropriately.

[0039] FIG. 6A is a diagram showing the relationship between the PWM control signal and the output pulse width measurement value according to the first embodiment, and is a diagram showing a case where the output pulse width measurement value is corrected. FIG. 6B is a diagram explaining the determination time for determining the absence of an output pulse in the first embodiment. In FIG. 6A, as in the example of FIG. 5, the output pulse width measurement value Wmon is updated to T2 at time 0.0167 seconds. Also, in the period included in the region A, there is no output pulse. On the other hand, in FIG. 6A, the signal level (low) of the PWM control signal SW at the last edge, that is, the falling edge F at time 0.0166 seconds, is obtained, and the output pulse width measurement value Wmon is corrected accordingly. In the graph at the bottom of FIG. 6A, the output pulse width measurement value Wmon (solid line) before correction and the output pulse width measurement value Wmon (dashed line) after correction are equal until time 0.0168 seconds, but correction is performed at time 0.0168 seconds, and the output pulse width measurement value Wmon after correction becomes zero.

[0040] The determination of the absence of an output pulse will be explained with reference to FIG. 6B. In FIG. 6B, the threshold th for determining the absence of an output pulse is set to 100 microseconds, which is the same as the PWM pulse period, and it is determined that there is no output pulse when the elapsed time from the last edge detection exceeds the threshold th. The elapsed time from the last edge detection is obtained by measuring the time count value as shown in the graph in the lower part of FIG. 6B. That is, the elapsed time is obtained from the difference dc (not shown) between the time count value at the current time Pt ​​and the time count value at the last edge detection time Ft. As can be seen from the graph in the upper part of FIG. 6B, the conversion from the time count value to the elapsed time (update of the elapsed time) is performed every 0.0001 seconds. In FIG. 6A and FIG. 6B, since the last edge detection time Ft is 0.0166 seconds, the elapsed time exceeds the threshold th at the time 0.0168 seconds. Therefore, it is determined that there is no output pulse at the time 0.0168 seconds, and the above-mentioned correction of the output pulse width measurement value Wmon is performed.

[0041] As described above, the output pulse width Wact can be accurately obtained by determining whether there is an output pulse based on the time elapsed since the last edge was detected and correcting the output pulse width measurement value Wmon to zero based on the level (low) of the PWM control signal SW when the last edge was detected. The same applies when the level of the PWM control signal SW when the last edge was detected was "high," in which case the output pulse width measurement value Wmon is corrected to the PWM pulse period. This means that even if the duty command is 0% or 100% and no edge of the output pulse is detected, the output pulse width Wact of the PWM control signal SW can be accurately obtained, and also that an abnormality can be correctly determined by comparing the command pulse width Wref and the output pulse width Wact.

[0042] 5 and 6A, the update timing of the output pulse width measurement value Wmon is set to the timing of the valley of the triangular wave for PWM generation, but the update timing is not limited to this. However, if the output pulse width measurement value Wmon is updated at the timing of the crest or valley of the triangular wave for PWM generation, the output pulse width measurement value Wmon is updated at the same timing as the update timing of general PWM control, which has the advantage that there is no need to provide a separate timer for updating the output pulse width measurement value Wmon.

[0043] <Hardware configuration of the control unit> Next, a hardware configuration for implementing the control unit according to the first embodiment will be described. FIG. 7 is a diagram showing an example of a hardware configuration for implementing the control unit according to the first embodiment. Each function of the control unit 10 is implemented by a processing circuit included in the control unit 10. Specifically, the control unit 10 includes an arithmetic processing unit 81 such as a CPU, a storage device 82 for storing data from the arithmetic processing unit 81 and for causing the arithmetic processing unit 81 to read the stored data, an input circuit 83 for inputting signals from an external device or the like to the arithmetic processing unit 81, and an output circuit 84 for outputting signals from the arithmetic processing unit 81 to the external device or the like. Data and signals are transmitted between the arithmetic processing unit 81, the storage device 82, the input circuit 83, and the output circuit 84 via a bus 85. Although not shown in the figure, when the control unit 10 is configured with a microcomputer as described above, the control unit 10 also includes a timer.

[0044] The arithmetic processing device 81 may be, for example, an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), or an FPGA (Field Programmable Gate Array). Alternatively, an arithmetic processing circuit formed by combining various logic circuits and signal processing circuits may be used. Furthermore, a configuration may be adopted in which a plurality of the above-mentioned arithmetic processing devices or arithmetic processing circuits are combined, and each arithmetic processing device and arithmetic processing circuit shares and executes each process.

[0045] The storage device 82 includes a RAM (Random Access Memory) configured to enable data to be read from and written to the arithmetic processing device 81, a ROM (Read Only Memory) configured to enable data to be read from the arithmetic processing device 81, and the like.

[0046] The input circuit 83 is connected to a sensor 71 and a switch 72 that monitor the state of the device 900 to be controlled, and inputs the output signals of the sensor 71 and the switch 72 to the arithmetic processing unit 81. It includes an AD conversion unit, an interface circuit of the input circuit, etc. (all are omitted in the figure).

[0047] The output circuit 84 is connected to the device 900 to be controlled, and includes an interface circuit (omitted in the figure) that converts and outputs the output signal from the arithmetic processing unit 81.

[0048] Each function provided by the control unit 10 is realized by the arithmetic processing unit 81 executing a software program stored in a storage device 82 such as a ROM and cooperating with other hardware of the control unit 10 such as the storage device 82, the input circuit 83, and the output circuit 84. Note that the setting data such as the threshold value used by the control unit 10 is stored in the storage device 82 such as a ROM as a part of the software program or as data separate from the software program.

[0049] Each function mounted inside the control unit 10 may be composed of software modules, or may be composed of a combination of software and hardware.

[0050] <Operation of the PWM control device> Next, the operation will be described. FIG. 8 is a flowchart showing the operation of the PWM control device in the first embodiment. First, a duty command Dref as a control command is generated (step ST101: control command generation step). As described above, the duty command Dref is generated based on a control command from a higher controller, an input from a user, or feedback from the device 900 to be controlled.

[0051] Next, a PWM control signal SW is generated according to the duty command Dref (step ST102: control signal generation step). As described above, the PWM control signal SW is generated by comparing the duty command Dref with a carrier wave (carrier).

[0052] Next, the output pulse width Wact of the PWM control signal SW is acquired (step ST103: output pulse width acquisition process). As described above, the output pulse width Wact is determined based on the output pulse width measurement value Wmon, which is measured by detecting the edges of the PWM control signal SW. Also, as described above, the output pulse width measurement value Wmon is corrected depending on the presence or absence of an output pulse. The output pulse width acquisition process will be described in detail later.

[0053] Next, a command pulse width Wref is calculated based on the duty command Dref (step ST104: command pulse width calculation step). Note that since the command pulse width Wref can be calculated if the duty command Dref is available, the command pulse width calculation step may be performed at any timing after the control command generation step and before the abnormality determination step described later.

[0054] Next, the output pulse width Wact is compared with the command pulse width Wref to determine whether or not there is an abnormality in the PWM control (step ST105: abnormality determination step). The abnormality determination step will be described later in detail.

[0055] Next, if it is determined in the anomaly determination step that there is an anomaly, the process proceeds to step ST107, and if it is determined that there is no anomaly, the process ends (step ST106).

[0056] If it is determined in the abnormality determination step that there is an abnormality, the generation and output of the PWM control signal SW is stopped (step ST107: output stop instruction step).

[0057] <Output pulse width acquisition process flow> The output pulse width acquisition step will be described below. Fig. 9 is a flow diagram showing the output pulse width acquisition step according to the embodiment 1. First, the edge of the PWM control signal SW is detected (step ST1031: output pulse detection step).

[0058] Next, the time counter is operated at the edge timing to obtain the edge time EdgT (step ST1032: edge time obtaining step).

[0059] Next, the signal level EdgLev of the PWM control signal SW at the edge timing is acquired as "high" or "low" (step ST1033: signal level acquisition step).

[0060] Next, the counter is operated at the edge timing, and the output pulse width measurement value Wmon is measured from the count value from the rising edge to the falling edge (or from the falling edge to the rising edge) (step ST1034: output pulse width measurement step).

[0061] Next, the presence or absence of an output pulse of the PWM control signal SW is determined based on the time elapsed since the last edge timing (step ST1035: output pulse presence / absence determination step). More specifically, the last edge timing, i.e., the time elapsed since the last edge detection time, is measured from the difference between the current time and the edge time EdgT, and if the time elapsed since the last edge timing is equal to or longer than the PWM pulse period, it is determined that there is no output pulse.

[0062] If it is determined that there is no output pulse, the process proceeds to step ST1037, and if it is determined that there is an output pulse, the output pulse width measurement value Wmon is set as the output pulse width Wact and the process ends (step ST1036).

[0063] If it is determined that there is no output pulse, the output pulse width measurement value Wmon is corrected, and the corrected output pulse width measurement value Wmon is set as the output pulse width Wact (step ST1037: output pulse width correction step). More specifically, if the signal level EdgLev is "low", the output pulse width measurement value Wmon is corrected to zero, and the "value of the output pulse width Wact=0". If the signal level EdgLev is "high", the output pulse width measurement value Wmon is corrected to the same value as the PWM pulse period, and the "value of the output pulse width Wact=PWM pulse period".

[0064] <Flow of the abnormality judgment process> The abnormality determination process will be described below. Fig. 10 is a flow chart showing the abnormality determination process according to the embodiment 1. First, a difference WDiff between the output pulse width Wact and the command pulse width Wref is calculated, and the difference WDiff is compared with a threshold value Dth (step ST1051: pulse width comparison process).

[0065] Next, if the difference WDiff is equal to or greater than the threshold value Dth, it is determined that there is an abnormality, and if the difference WDiff is less than the threshold value Dth, it is determined that there is no abnormality (normal) (step ST1052: difference abnormality determination step).

[0066] According to the first embodiment, even when the duty command is 0% or 100%, an abnormality can be detected, and an abnormality in PWM control occurring in the PWM control device can be detected. More specifically, the PWM control device includes an output pulse width acquisition means for acquiring an output pulse width of a PWM control signal, a command pulse width calculation means for calculating a command pulse width, which is the pulse width of the duty command, and an abnormality determination means for determining the presence or absence of an abnormality in PWM control by comparing the output pulse width with the command pulse width. The output pulse width acquisition means measures an output pulse width measurement value, which is a measurement value of the width of the output pulse of the PWM control signal, based on the edge of the PWM control signal, and when it is determined that there is no output pulse by determining the presence or absence of an output pulse of the PWM control signal, corrects the output pulse width measurement value and sets the corrected output pulse width measurement value as the output pulse width. When there is a difference between the output pulse width and the command pulse width that is greater than a threshold value, it indicates that some abnormality has occurred in the PWM control device. Therefore, an abnormality in PWM control occurring in the PWM control device can be detected.

[0067] Furthermore, if it is determined that there is no output pulse when acquiring the output pulse width, the output pulse width measurement value is corrected and the corrected output pulse width measurement value is set as the output pulse width. As a result, if there is an output pulse width, the output pulse width measurement value measured based on the edge is set as the output pulse width, and if there is no output pulse such as when the duty command is 0% or 100%, the corrected value of the last measured output pulse width measurement is set as the output pulse width. As a result, the output pulse width can be acquired even when the duty command is 0% or 100%, and an abnormality can be detected by comparing it with the command pulse width.

[0068] In addition, there is no need to provide an additional dedicated circuit or hardware for abnormality determination. More specifically, the abnormality determination means determines the presence or absence of an abnormality by comparing two pulse widths, and does not compare signal levels. Therefore, a dedicated circuit for comparing signal levels is not required.

[0069] In the first embodiment, an abnormality in PWM control is determined by comparing the command pulse width with the output pulse width. However, the output pulse width may be converted into a duty output according to the PWM pulse period, and an abnormality in PWM control may be determined by comparing the duty command with the duty output.

[0070] Embodiment 2 Next, a second embodiment will be described with reference to Fig. 11 to Fig. 18. In the second embodiment, the controlled device includes an electric motor, and the PWM control device is included in a power conversion device for operating the electric motor. That is, a PWM control device similar to that of the first embodiment is applied to the power conversion device for operating the electric motor. More specifically, the PWM control device of the second embodiment outputs a plurality of PWM control signals to control the electric motor, includes a rotation state acquisition means for acquiring the rotation state of the electric motor, performs an abnormality judgment and a normality judgment of the PWM control according to the rotation state of the electric motor, and sets a signal level for stopping the output of the PWM control according to the control state of the plurality of PWM control signals when an abnormality is judged.

[0071] The configuration and operation of the PWM control device of the second embodiment will be described below, focusing on the differences from the first embodiment. Note that the same or corresponding parts as those of the first embodiment are denoted by the same reference numerals.

[0072] <Configuration of power conversion device> 11 is a block diagram showing a configuration of a power conversion device according to embodiment 2. The power conversion device 1000 is a power conversion device that supplies AC power to an electric motor 901 to operate the electric motor 901, and includes a PWM control device 200 that generates a PWM control signal, and a drive circuit 903 that generates a drive signal for driving a three-phase inverter circuit 902 from the PWM control signal supplied from the PWM control device 200. The power conversion device 1000 also includes a three-phase (U-phase, V-phase, W-phase) AC bus 904 that connects the inverter circuit 902 and the electric motor 901, and a current sensor 905 that detects a current flowing through the AC bus 904 and outputs current detection values ​​of the respective phases (a U-phase current detection value Iu, a V-phase current detection value Iv, and a W-phase current detection value Iw, hereinafter referred to as three-phase current detection values ​​Iu, Iv, and Iw). Furthermore, the power conversion device 1000 includes a voltage sensor 906 that detects a DC voltage input from a DC power source 51 to a DC bus (not shown) of the inverter circuit 902 and outputs the detected DC voltage as an input voltage Vpn. The three-phase current detection values ​​Iu, Iv, Iw and the input voltage Vpn are input to a control unit 20 of the PWM control device 200. Note that the power conversion device 1000 is intended to be used in, for example, electric vehicles, plug-in hybrid vehicles, and other electrically powered vehicles, for driving an electric motor as a power source with power from a high-voltage battery.

[0073] The controlled device 900 is a control target of the PWM control device 200 as in the first embodiment, and some of the configuration overlaps with the power conversion device 1000. The controlled device 900 includes an electric motor 901, an inverter circuit 902, and a drive circuit 903. The electric motor 901 is an electric motor that rotates and drives a load (not shown) and can regenerate the rotational energy of the load as electric energy, and includes, for example, a permanent magnet three-phase AC synchronous motor or a three-phase brushless motor. The electric motor 901 is provided with a rotation angle sensor 907 that detects a rotor rotation angle θm of the electric motor 901. The rotation angle sensor 907 detects a rotor rotation angle θm of the rotor (not shown) of the electric motor 901 by a resolver, an encoder, or the like. The rotor rotation angle θm detected by the rotation angle sensor 907 is output to the control unit 20 of the PWM control device 200. The controlled device 900 also includes the AC bus 904, the current sensor 905, and the voltage sensor 906 described above.

[0074] The electric motor 901 operates by being supplied with an AC current by the inverter circuit 902. In addition, in a regenerative state of the electric motor 901, the generated regenerative power is charged to the DC power supply 51 via the inverter circuit 902. Note that the object to be controlled by the PWM control device 200 is not limited to an electric motor, and may be something other than an electric motor.

[0075] The inverter circuit 902 is connected to the DC power supply 51 by, for example, a DC bus on the positive electrode side and a DC bus on the negative electrode side (both not shown). It supplies driving power from the DC power supply 51 and supplies regenerative power to the DC power supply 51. Further, the inverter circuit 902 is connected to the motor 901 by the AC bus 904, supplies driving power to the motor 901, and receives regenerative power from the motor 901. Although not shown, the inverter circuit 902 is an inverter in which six generally well-known switching elements are connected in a full-bridge configuration, and has switching elements on the upper side of the U phase, the upper side of the V phase, the upper side of the W phase, the lower side of the U phase, the lower side of the V phase, and the lower side of the W phase. Each switching element is a semiconductor switching element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) with a built-in diode between the source and drain, for example. Note that the type and number of semiconductor switching elements are not limited to this, and semiconductor switching elements such as IGBT (Insulated Gate Bipolar Transistor) and SiC-MOSFET may be used.

[0076] The drive circuit 903 receives a PWM control signal from the control unit 20 of the PWM control device 200 and generates six drive signals (not shown) corresponding to the PWM control signal. Each switching element of the inverter circuit 902 is switched on and off by the drive signal generated by the drive circuit 903. The inverter circuit 902 converts the DC power supplied from the DC power supply 51 into AC by switching on and off each switching element, and supplies three-phase AC current to the motor 901.

[0077] <Configuration of the PWM control device> The PWM control device 200 includes a control unit 20, and transmits a PWM control signal generated by the control unit 20 to the controlled device 900. The control unit 20 generates PWM control signals corresponding to the switching elements of the inverter circuit 902, i.e., a PWM control signal SW_UH corresponding to the U-phase upper switching element, a PWM control signal SW_VH corresponding to the V-phase upper switching element, a PWM control signal SW_WH corresponding to the W-phase upper switching element, a PWM control signal SW_UL corresponding to the U-phase lower switching element, a PWM control signal SW_VL corresponding to the V-phase lower switching element, and a PWM control signal SW_WL corresponding to the W-phase lower switching element, and outputs the generated signals to a drive circuit 903.

[0078] In the following description, the six PWM control signals are collectively referred to as PWM control signal SW**. Also, a reference symbol followed by "_UH" indicates that it corresponds to a switching element on the upper side of the U phase of the inverter circuit 902, or a PWM control signal that controls a switching element on the upper side of the U phase. Similarly, a reference symbol followed by "_VH" corresponds to the upper side of the V phase, a reference symbol followed by "_WH" corresponds to the upper side of the W phase, a reference symbol followed by "_UL" corresponds to the lower side of the U phase, a reference symbol followed by "_VL" corresponds to the lower side of the V phase, and a reference symbol followed by "_WL" corresponds to the lower side of the W phase.

[0079] <Control unit function block> 12 is a block diagram showing a configuration of a control unit according to embodiment 2. The control unit 20 includes a control command generating means 21 that generates three-phase duty commands as control commands, i.e., a U-phase duty command Dref_u, a V-phase duty command Dref_v, and a W-phase duty command Dref_w (hereinafter, referred to as three-phase duty commands Dref_u, Dref_v, and Dref_w) and outputs the three-phase duty commands Dref_u, Dref_v, and Dref_w to a command pulse width calculating means 23 and a control signal generating means 29, and a PWM control signal SW** that is generated based on the three-phase duty commands Dref_u, Dref_v, and Dref_w and outputs the PWM control signal SW** to a controlled device 900 (not shown in FIG. 12) and an output pulse width acquiring means 22. the control signal generating means 29 acquiring an output pulse width Wact** (Wact_UH, Wact_VH, Wact_WH, Wact_UL, Wact_VL, Wact_WL) which is the pulse width of each PWM control signal SW** and outputting the output pulse width Wact** to the abnormality determination means 27; and a command pulse width calculating means 23 calculating a command pulse width Wref** (Wref_UH, Wref_VH, Wref_WH, Wref_UL, Wref_VL, Wref_WL) based on the three-phase duty commands Dref_u, Dref_v, Dref_w and outputting the command pulse width Wref** to the abnormality determination means 27.

[0080] The control unit 20 further includes an abnormality determination means 27 which determines the presence or absence of an abnormality in the PWM control from the comparison result between each output pulse width Wact** and each command pulse width Wref** and outputs the result as a state determination result ErrSt** (ErrSt_UH, ErrSt_VH, ErrSt_WH, ErrSt_UL, ErrSt_VL, ErrSt_WL), and an output stop instruction means 18 which receives the state determination result ErrSt** from the abnormality determination means 27 and outputs a stop instruction signal Stp to the control signal generation means 29 in accordance with the state determination result ErrSt**. The abnormality determination means 27 determines the presence or absence of an abnormality for each of the upper U phase, etc. by performing an abnormality determination by comparing the output pulse width Wact** with the command pulse width Wref** for each of the upper U phase, etc.

[0081] The control unit 20 also includes a rotation state acquisition means 25 that calculates an electrical angle θe and an electrical angle period Tω based on the rotor rotation angle θm, outputs the electrical angle θe to the control command generation means 21, and outputs the electrical angle period Tω to a normal control determination means 26, and a normal control determination means 26 that determines that the PWM control is operating normally based on the electrical angle period Tω and the state determination result ErrSt**.

[0082] The control command generating means 21 will be described. FIG. 13 is a block diagram showing the configuration of the control command generating means according to the second embodiment. Examples of control commands for controlling the electric motor 901 include a torque command, a current command, and a voltage command. In the second embodiment, the torque command Trq* is used as the control command as an example. The control command generating means 21 includes a current command generating unit 21a that generates a current command in the dq-axis coordinate system, i.e., a d-axis current command Id* and a q-axis current command Iq*, based on the torque command Trq*; a three-phase to two-phase conversion unit 21c that converts the three-phase current detection values ​​Iu, Iv, and Iw into current detection values ​​in the dq-axis coordinate system, i.e., the d-axis current detection value Id and the q-axis current detection value Iq; and a dq-axis current detection value Iq* that converts the dq-axis current detection value Id and the q-axis current detection value Iq, based on the deviation ΔId (not shown) between the d-axis current command Id* and the d-axis current detection value Id, and the deviation ΔIq (not shown) between the q-axis current command Iq* and the q-axis current detection value Iq. the voltage command generating unit 21b that generates voltage commands in a reference system, i.e., a d-axis voltage command Vdc and a q-axis voltage command Vqc; a two-phase to three-phase conversion unit 21d that converts the d-axis voltage command Vdc and the q-axis voltage command Vqc into three-phase voltage commands, i.e., a U-phase voltage command Vuc, a V-phase voltage command Vvc and a W-phase voltage command Vwc (hereinafter referred to as three-phase voltage commands Vuc, Vvc, Vwc); and a duty command calculation unit 21e that calculates three-phase duty commands Dref_u, Dref_v, Dref_w based on the three-phase voltage commands Vuc, Vvc, Vwc.

[0083] The current command generating unit 21a receives a torque command Trq* from a host controller or a host system (not shown) and generates a d-axis current command Id* and a q-axis current command Iq* based on the torque command Trq*. In the dq-axis coordinate system, the d-axis indicates the magnetic pole position of the electric motor 901, i.e., the direction of the magnetic flux, and the q-axis indicates a direction electrically perpendicular to the d-axis. The dq-axis coordinate system is a rotating coordinate system, and when the rotor of the electric motor 901 having a magnet rotates, the dq-axis coordinate system also rotates.

[0084] The voltage command generating unit 21b performs current feedback calculations on current commands in the dq-axis coordinate system, and generates a d-axis voltage command Vdc and a q-axis voltage command Vqc so that the deviation ΔId for the d-axis current and the deviation ΔIq for the q-axis current converge to zero, respectively.

[0085] The three-phase to two-phase conversion unit 21c receives the three-phase current detection values ​​Iu, Iv, Iw and the electrical angle θe from the current sensor 905 and the rotational state acquisition means 25, and converts the three-phase current detection values ​​Iu, Iv, Iw into a d-axis current detection value Id and a q-axis current detection value Iq, which are current detection values ​​in the dq-axis coordinate system, using the electrical angle θe.

[0086] The two-phase to three-phase conversion unit 21d receives the d-axis voltage command Vdc and the q-axis voltage command Vqc from the voltage command generation unit 21b and the electrical angle θe from the rotation state acquisition means 25, and converts the d-axis voltage command Vdc and the q-axis voltage command Vqc into three-phase voltage commands Vuc, Vvc, and Vwc using the electrical angle θe. It is preferable that the three-phase voltage commands Vuc, Vvc, and Vwc are set to be equal to or lower than the input voltage Vpn input to the inverter circuit 902.

[0087] The duty command calculation unit 21e receives the three-phase voltage commands Vuc, Vvc, and Vwc from the two-phase to three-phase conversion unit 21d and the input voltage Vpn from the voltage sensor 906, and generates three-phase duty commands Dref_u, Dref_v, and Dref_w from the three-phase voltage commands Vuc, Vvc, and Vwc and the input voltage Vpn. At this time, the duty command calculation unit 21e generates three-phase duty commands Dref_u, Dref_v, and Dref_w corresponding to the optimal correction control command. The duty command calculation unit 21e outputs the generated three-phase duty commands Dref_u, Dref_v, and Dref_w to the control signal generation means 29.

[0088] The output pulse width acquisition means 22 acquires the output pulse width Wact**. As described above, the output pulse width Wact** includes six output pulse widths. The acquisition of each output pulse width is similar to that of the output pulse width acquisition means 12 in the first embodiment.

[0089] The command pulse width calculation means 23 calculates the command pulse width Wref**. As described above, the command pulse width Wref** includes six command pulse widths. The calculation of each command pulse width is similar to that of the command pulse width calculation means 13 in the first embodiment.

[0090] The rotation state acquisition means 25 will be described. FIG. 14 is a block diagram showing the configuration of the rotation state acquisition means according to the second embodiment. The rotation state acquisition means 25 includes an electrical angle calculation unit 25a that receives a rotor rotation angle θm of the electric motor 901 from a rotation angle sensor 907 and converts the rotor rotation angle θm into an electrical angle θe based on the number of pole pairs of the electric motor 901, and an electrical angle period calculation unit 25b that calculates an electrical angle period Tω from the electrical angle θe. The electrical angle calculation unit 25a outputs the calculated electrical angle θe to the control command generation means 21 and the electrical angle period calculation unit 25b. The electrical angle period calculation unit 25b outputs the calculated electrical angle period Tω to the abnormality determination means 27 and the normal control determination means 26. The electrical angle period Tω is an example of a time determined based on the rotation state of the electric motor 901.

[0091] The normal control determination means 26 determines whether the PWM control is operating normally without the PWM control signal SW** being stuck, based on the determination result by the abnormality determination means 27 and the rotation state of the electric motor 901 acquired by the rotation state acquisition means 25. Here, "sticking" refers to the PWM control signal SW** continuing to maintain a "high" or "low" state in an unintended manner, and indicates an abnormal state in which the signal level of the PWM control signal SW** cannot be switched normally. The PWM control signal SW** may be stuck when an input from a sensor or the like cannot be taken in due to an abnormality in the input circuit of the PWM control device 200, when memory rewriting is not performed normally, when the arithmetic device is not operating normally, etc. In addition, when the control unit 20 is configured with a microcomputer, the PWM control signal SW** may also be stuck when there is an abnormality in the output circuit of the microcomputer (for example, when the register value of the output timer used for PWM control is not updated normally).

[0092] The normal control determination means 26 determines that the PWM control is normal when the state determination result ErrSt** by the abnormality determination means 27 described later is "normal" for more than half the electrical angle period Tω (hereinafter referred to as "Tω / 2"). The details of the normality determination of the PWM control will be described later.

[0093] The abnormality determination means 27 will be described. FIG. 15 is a block diagram showing the configuration of the abnormality determination means according to the second embodiment. The abnormality determination means 27 includes a pulse width comparison unit 27a that calculates a difference WDiff** (WDiff_UH, WDiff_VH, WDiff_WH, WDiff_UL, WDiff_VL, WDiff_WL) between a command pulse width Wref** and an output pulse width Wact**, a difference abnormality determination unit 27b that determines the presence or absence of an abnormality in the difference WDiff** and outputs the result as a difference abnormality determination result ErrD** (ErrD_UH, ErrD_VH, ErrD_WH, ErrD_UL, ErrD_VL, ErrD_WL), and a pulse width fixation time FixT** (FixT_UH, FixT_VH, FixT_WH, FixT_UL, FixT_VL, FixT_WL). ixT_WL), a rotation fluctuation determination unit 27d which determines whether or not there is a time fluctuation in the ideal value of the PWM control command, a control command abnormality determination unit 27e which determines whether or not there is an abnormality in the control command for PWM control and outputs the result as a control command abnormality determination result ErrR** (ErrR_UH, ErrR_VH, ErrR_WH, ErrR_UL, ErrR_VL, ErrR_WL), and an abnormality presence / absence determination unit 27f which determines whether or not there is an abnormality based on the difference abnormality determination result ErrD** and the control command abnormality determination result ErrR** and outputs the result as an abnormality determination result Err** (Err_UH, Err_VH, Err_WH, Err_UL, Err_VL, Err_WL).

[0094] The abnormality judgment means 27 also includes an on-stick judgment unit 27g that judges whether the output pulse of the PWM control signal SW** is stuck on and outputs the result as an on-stick judgment result FixON** (FixON_UH, FixON_VH, FixON_WH, FixON_UL, FixON_VL, FixON_WL), an off-stick judgment unit 27h that judges whether the output pulse of the PWM control signal SW** is stuck off and outputs the result as an off-stick judgment result FixOFF** (FixOFF_UH, FixOFF_VH, FixOFF_WH, FixOFF_UL, FixOFF_VL, FixOFF_WL), and a control state judgment unit 27i that judges the state of PWM control based on the abnormality judgment result Err**, the on-stick judgment result FixON** and the off-stick judgment result FixOFF** and outputs the result as a state judgment result ErrSt**.

[0095] The pulse width comparison unit 27a receives the command pulse width Wref** and the output pulse width Wact** from the command pulse width calculation means 23 and the output pulse width acquisition means 22, respectively. As described above, the command pulse width Wref** and the output pulse width Wact** include six command pulse widths and output pulse widths corresponding to each switching element of the inverter circuit 902, such as the upper side of the U phase. The pulse width comparison unit 27a calculates the difference between the corresponding command pulse width and output pulse width, and calculates the difference WDiff**. The pulse width comparison unit 27a outputs the difference WDiff** to the difference anomaly determination unit 27b.

[0096] The difference anomaly determination unit 27b determines whether each of the six differences included in the difference WDiff** is equal to or greater than the threshold value Dth. As a result, the difference anomaly determination result ErrD** indicates the presence or absence of a difference anomaly for each switching element, such as the upper side of the U phase. The difference anomaly determination unit 27b outputs the difference anomaly determination result ErrD** to the anomaly presence / absence determination unit 27f.

[0097] The pulse width fixation time measurement unit 27c receives the output pulse width Wact** from the output pulse width acquisition means 22, and measures the time during which the same value continues for each output pulse width included in the output pulse width Wact** as the pulse width fixation time. The pulse width fixation time measurement unit 27c outputs the pulse width fixation time FixT** to the control command abnormality determination unit 27e and the on-fixation determination unit 27g. Note that when the PWM pulse period is changed, the upper limit value of the output pulse width changes, so the pulse width fixation time measurement unit 27c also measures the time during which the upper limit value of the output pulse width continues as the fixation time.

[0098] The rotational fluctuation determination unit 27d determines whether or not there is a time fluctuation in the ideal value of the PWM control command (three-phase duty commands Dref_u, Dref_v, Dref_w) to be output. The rotational fluctuation determination unit 27d receives a torque command Trq* from a higher-level controller or higher-level system (not shown) and determines that there is no time fluctuation when the torque command Trq* is zero, and determines that there is a time fluctuation when the torque command Trq* is non-zero. The rotational fluctuation determination unit 27d outputs the above determination result as the time fluctuation presence / absence Ref_v to the control command abnormality determination unit 27e. In the second embodiment, the presence / absence of a time fluctuation in the ideal value of the PWM control command is determined according to the torque command Trq*, but the presence / absence of a time fluctuation in the ideal value of the PWM control signal SW** may be determined according to the duty command (three-phase duty commands Dref_u, Dref_v, Dref_w). For example, when the duty command is 50%, it may be determined that there is no time fluctuation.

[0099] The control command abnormality determination unit 27e receives the pulse width fixation time FixT** and the electrical angle period Tω from the pulse width fixation time measurement unit 27c and the rotation state acquisition means 25, and receives the time fluctuation Ref_v from the rotation fluctuation determination unit 27d. If the time fluctuation Ref_v is "time fluctuation present" and the pulse width fixation time FixT** is Tω / 2 or more, the control command abnormality determination unit 27e determines that "a control command abnormality exists," and if the above condition is not satisfied, that is, if the time fluctuation Ref_v is "no time fluctuation" or the pulse width fixation time FixT** is less than Tω / 2, it determines that "no control command abnormality exists."

[0100] The control command abnormality determination unit 27e may not perform the determination when the rotation speed of the motor 901 is equal to or lower than a predetermined rotation speed. In this case, the control command abnormality determination unit 27e performs the determination of the control command abnormality only when the rotation speed of the motor 901 is higher than the predetermined rotation speed. The values ​​of the three-phase duty commands Dref_u, Dref_v, and Dref_w are determined according to the electrical angle θe. However, the electrical angle θe changes according to the rotation of the motor 901. Therefore, if the motor 901 is not rotating, the electrical angle θe becomes a fixed value, and even if the PWM control is normal, the values ​​of the three-phase duty commands Dref_u, Dref_v, and Dref_w may continue to be the same. If the control command abnormality determination is performed only when the rotation speed of the motor 901 is higher than the predetermined rotation speed as described above, it is possible to prevent erroneous detection of an abnormality when the motor 901 is not rotating. The rotation speed of the electric motor 901 may be obtained by the rotation state obtaining means 25 by calculating the change in the rotor rotation angle θm over time.

[0101] Although the control command abnormality determination unit 27e in the second embodiment determines the presence or absence of a control command abnormality using the fixation time of the output pulse width Wact**, the control command abnormality may be determined using the fixation time of the command pulse width Wref**. In this case, the command pulse width Wref** is input to the pulse width fixation time measurement unit 27c, and the pulse width fixation time measurement unit 27c measures the time during which the same value continues for each command pulse width included in the command pulse width Wref** as the pulse width fixation time.

[0102] In addition, when the pulse width fixation time FixT** is equal to or greater than Tω / 2, it is determined that there is a control command abnormality. However, a time smaller than Tω / 2 may be used as the determination value in determining whether or not there is a control command abnormality. In this case, the control command abnormality is detected at an earlier stage.

[0103] The abnormality presence / absence determination unit 27f receives the difference abnormality determination result ErrD** and the control command abnormality determination result ErrR** from the difference abnormality determination unit 27b and the control command abnormality determination unit 27e, respectively, and determines that an abnormality exists when at least one of the difference abnormality determination result ErrD** and the control command abnormality determination result ErrR** is abnormal, and determines that no abnormality exists when neither is abnormal, and outputs the result as the abnormality determination result Err** to the control state determination unit 27i. The difference abnormality determination result ErrD** and the control command abnormality determination result ErrR** each include six determination results corresponding to each switching element of the inverter circuit 902. Therefore, the abnormality presence / absence determination unit 27f also determines the presence / absence of an abnormality for each. For example, if the difference abnormality judgment result for the upper U phase is "abnormality present" and "control command abnormality judgment result: no abnormality" and the difference abnormality judgment result for the upper V phase is "no abnormality" and "control command abnormality judgment result: no abnormality", the abnormality judgment result Err** will indicate "abnormality present" for the upper U phase and "no abnormality" for the upper V phase.

[0104] As described above, by combining the abnormality judgment based on the difference between the command pulse width and the output pulse width with the abnormality judgment regarding the control command, it is possible to detect abnormalities in PWM control even when memory rewriting is not performed normally within the control unit 20 or when the arithmetic device is not operating normally.

[0105] The on-fixed determination unit 27g receives the output pulse width Wact** and the pulse width fixation time FixT** from the output pulse width acquisition means 22 and the pulse width fixation time measurement unit 27c, respectively, and determines whether or not each switching element of the inverter circuit 902 is stuck on the on state based on the output pulse width Wact** and the pulse width fixation time FixT**, and outputs the result as the on-fixed determination result FixON** to the control state determination unit 27i. When the pulse width fixation time FixT** is equal to or longer than a predetermined time (for example, equal to or longer than Tω / 2) and the output pulse width Wact** is a PWM pulse period, the on-fixed determination unit 27g determines that the on-fixed state has occurred (the PWM control signal is unintentionally maintained at a high state). As described above, the determination of the presence or absence of the on-fixed state is performed for each switching element of the inverter circuit 902. For this reason, the on-fixed determination result FixON** includes six on-fixed determination results, such as the upper side of the U phase.

[0106] The off-fixed determination unit 27h receives the output pulse width Wact** and the pulse width fixation time FixT** from the output pulse width acquisition means 22 and the pulse width fixation time measurement unit 27c, respectively, and determines whether or not each switching element of the inverter circuit 902 is stuck off based on the output pulse width Wact** and the pulse width fixation time FixT**, and outputs the result as the off-fixed determination result FixOFF** to the control state determination unit 27i. When the pulse width fixation time FixT** is equal to or longer than a predetermined time (for example, equal to or longer than Tω / 2) and the output pulse width Wact** is zero, the off-fixed determination unit 27h determines that the off-fixed state has occurred (the PWM control signal is unintentionally maintained at a low state). As described above, the determination of the presence or absence of the off-fixed state is performed for each switching element of the inverter circuit 902. For this reason, the off-fixed determination result FixOFF** includes six off-fixed determination results, such as the U-phase upper side.

[0107] The control state determination unit 27i receives the abnormality determination result Err** from the abnormality presence / absence determination unit 27f, and receives the on-stick determination result FixON** and the off-stick determination result FixOFF** from the on-stick determination unit 27g and the off-stick determination unit 27h, respectively. The control state determination unit 27i determines the state of PWM control based on the abnormality determination result Err**, the on-stick determination result FixON**, and the off-stick determination result FixOFF**, and outputs the state determination result ErrSt** to the output stop instruction means 28 and the normal control determination means 26.

[0108] The state determination result ErrSt** includes "normal", "ON-fixed abnormality", "OFF-fixed abnormality" and "pulse abnormality". When the abnormality determination result Err** is "abnormal", the control state determination unit 27i determines the state determination result ErrSt** to be "normal". When the abnormality determination result Err** is "abnormal" and the ON-fixed determination result FixON** is "on-fixed", the state determination result ErrSt** is "ON-fixed abnormality". When the abnormality determination result Err** is "abnormal" and the OFF-fixed determination result FixOFF** is "off-fixed", the state determination result ErrSt** is "off-fixed abnormality". When the abnormality determination result Err** is "abnormal", and the ON-fixed determination result FixON** and the OFF-fixed determination result FixOFF** are "no ON-fixed" and "no OFF-fixed", respectively, the control state determination unit 27i determines the state determination result ErrSt** to be "pulse abnormality". As described above, "on-stuck abnormality" and "off-stuck abnormality" indicate what type of abnormality exists when the abnormality determination means 27 determines that there is an abnormality in the PWM control, and the determination of the presence or absence of an on-stuck state and the presence or absence of an off-stuck state may be performed separately from the determination of the presence or absence of an abnormality in the PWM control. For this reason, the on-stuck determination unit 27g and the off-stuck determination unit 27h do not necessarily need to be provided in the abnormality determination means 27. In addition, the pulse width fixation time measurement unit 27c also measures the pulse width fixation time of the output pulse width Wact** and does not itself perform abnormality determination, so it does not necessarily need to be provided in the abnormality determination means 27.

[0109] The state determination result ErrSt** also includes six state determination results corresponding to the respective switching elements of the inverter circuit 902, for example, the upper side of the U phase.

[0110] The output stop instruction means 28, like the output stop instruction means 18 in the first embodiment, stops the generation of the PWM control signal SW** by the control signal generating means 29 in accordance with the state of PWM control indicated by the state determination result ErrSt**. As described above, the state determination result ErrSt** includes six state determination results corresponding to each switching element of the inverter circuit 902, such as the state determination result of the upper side of the U phase. Therefore, the output stop instruction means 28 generates a stop instruction signal Stp in accordance with the state of each PWM control signal corresponding to each switching element.

[0111] In the second embodiment, the PWM control device 200 is applied to the power conversion device 1000 for operating the electric motor 901, and generates a stop instruction signal Stp for setting the level of the PWM control signal according to the control state of each of the multiple PWM control signals SW**. For example, in order to stop the phase current of the electric motor 901 in the inverter circuit 902 and prevent power from being regenerated on the input side of the inverter circuit 902, the output of the PWM control signal SW** may be stopped so as to turn on all of the upper switching elements or all of the lower switching elements of the inverter circuit 902 and to short-circuit the phases of the electric motor 901 with each other, creating a so-called three-phase short-circuit state.

[0112] For example, when the state determination result ErrSt_UH for the U-phase upper PWM control signal SW_UH is "stuck-off abnormal", even if an instruction is given to stop the output of the PWM control signal SW** so that all the upper switching elements of the inverter circuit 902 are turned on and all the lower switching elements are turned off to form a three-phase short circuit, the U-phase upper switching elements remain off, so that a three-phase short circuit cannot be formed. Therefore, the output stop instruction means 28 generates a stop instruction signal Stp according to the normal or abnormal state of the multiple PWM control signals SW** and outputs it to the control signal generation means 29.

[0113] If all the state determination results ErrSt** are "normal", the output stop instruction means 28 does not issue an instruction to stop output.

[0114] When the state determination result ErrSt** for any of the upper switching elements (for example, the upper side of the U phase) is "stuck on abnormality", the output stop instruction means 28 generates a stop instruction signal Stp that sets the signal levels of the PWM control signals for all the upper switching elements, i.e., the PWM control signals SW_UH, SW_VH, and SW_WH, to "high", and sets the signal levels of the PWM control signals for all the lower switching elements, i.e., the PWM control signals SW_UL, SW_VL, and SW_WL, to "low". The same applies when the state determination result ErrSt** for any of the lower switching elements is "stuck on abnormality".

[0115] When the state determination result ErrSt** for any of the upper switching elements (for example, the upper side of the U phase) is "stuck-off abnormality", the output stop instruction means 28 generates a stop instruction signal Stp that sets the signal levels of the PWM control signals for all the upper switching elements, i.e., the PWM control signals SW_UH, SW_VH, and SW_WH, to "low" and the signal levels of the PWM control signals for all the lower switching elements, i.e., the PWM control signals SW_UL, SW_VL, and SW_WL, to "high". The same applies when the state determination result ErrSt** for any of the lower switching elements is "stuck-off abnormality".

[0116] As described above, in the case of a "stuck-on abnormality", all PWM control signals for switching elements on the same side (upper or lower side) as the switching element determined to have an "stuck-on abnormality" are set to "high", and all PWM control signals for switching elements on the opposite side (lower or upper side) are set to "low". In the case of a "stuck-off abnormality", all PWM control signals for switching elements on the same side (upper or lower side) as the switching element determined to have an "stuck-off abnormality" are set to "low", and all PWM control signals for switching elements on the opposite side (lower or upper side) are set to "high". In this way, the output stop instruction means 28 sets the state of the switching elements when output is stopped according to the type of abnormality.

[0117] For the PWM control signal for the switching element whose state determination result ErrSt** is "abnormal pulse", the output stop instruction means 28 generates a stop instruction signal Stp for stopping the output of the PWM control signal.

[0118] The control signal generating means 29 generates and outputs a PWM control signal SW** for controlling the controlled device 900 according to the three-phase duty commands Dref_u, Dref_v, and Dref_w. The generation of the PWM control signal SW by the control signal generating means 29 is performed by comparing the three-phase duty commands Dref_u, Dref_v, and Dref_w with a carrier, similarly to the control signal generating means 19 in the first embodiment, but the control signal generating means 29 generates six PWM control signals SW** corresponding to the switching elements of the inverter circuit 902. When the control signal generating means 29 receives a stop instruction signal Stp from the output stop instruction means 28, the control signal generating means 29 stops the generation and output of part or all of the PWM control signals SW** according to the content of the stop instruction signal Stp. Alternatively, the control signal generating means 29 sets the level of the signal to "high" or "low".

[0119] With the above configuration, when the electric motor 901 is the control target, it is possible to instruct the output of the PWM control signal to be stopped in accordance with the control states of the multiple PWM control signals SW**, and to stop the electric motor 901 early if an abnormality occurs in the PWM control.

[0120] Three features of the PWM control device 200 in the second embodiment will be described. The first is the normality determination by the normal control determination means 26 described above. As described above, it is determined that the PWM control is normal based on the abnormality determination result by the abnormality determination means 27 and the rotation state (electrical angle period Tω) of the electric motor 901 acquired by the rotation state acquisition means 25. This makes it possible to confirm that the PWM control signal SW** is not stuck and that the PWM control is operating normally.

[0121] The second is that the abnormality determination means 27 determines an abnormality in the PWM control from the rotational state (electrical angle period Tω) of the electric motor 901 and the output pulse width Wact** acquired by the rotational state acquisition means 25, even if there is no difference between the output pulse width Wact** and the command pulse width Wref**.

[0122] The third point is that the abnormality determination means 27 determines whether the PWM control signal SW** is stuck on or off abnormally by measuring the time during which the output pulse width is constant, and the output stop instruction means 28 generates a stop instruction signal Stp according to the abnormal state of each PWM control signal SW** signal corresponding to each switching element.

[0123] In the second embodiment, as in the first embodiment, even when the duty command is 0% or 100%, an accurate output pulse width Wact** can be obtained by correcting the output pulse width measurement value Wmon. Therefore, as in the first embodiment, it is possible to correctly perform an abnormality determination based on the comparison result (difference WDiff**) between the command pulse width Wref** and the output pulse width Wact**.

[0124] However, when the PWM duty command is 0% or 100%, even if there is no difference between the command pulse width Wref** and the output pulse width Wact**, if there is a possibility that the PWM control signal SW** is stuck as described above, it is not certain whether the PWM control is actually operating according to the duty command. The normal control determination means 26 of the second embodiment determines that normal PWM control is being performed even in such a case. This will be explained below.

[0125] 16 is a diagram comparing the time waveform of the electrical angle with the time waveform of the PWM control signal on the upper side of the U phase in the second embodiment, where the upper graph shows the time waveform of the electrical angle θe, and the lower graph shows the PWM control signal SW_UH on the upper side of the U phase. As described above, the three-phase voltage commands Vuc, Vvc, and Vwc are calculated based on the d-axis voltage command Vdc and the q-axis voltage command Vqc, and the electrical angle θe, so that the three-phase duty commands Dref_u, Dref_v, and Dref_w calculated based on the three-phase voltage commands Vuc, Vvc, and Vwc, and the PWM control signal SW** generated based on the three-phase duty commands Dref_u, Dref_v, and Dref_w fluctuate with an electrical angle period Tω. In such a case, if the PWM control is operating normally, the state in which the duty command is 0% or 100% will not continue for more than Tω / 2. In other words, if the state determination result ErrSt**, which is the output of the abnormality determination means 27, continues to be in the "normal" state for Tω / 2 or more, the signal level of the PWM control signal SW** becomes "high" or " It can be said that the PWM control is operating normally without being stuck at "low." In FIG. 16, there is a period T3 in which there is no output pulse of the PWM control signal around time 0.017 seconds, but the period T3 never exceeds Tω / 2. This is why the normal control determination means 26 determines that the PWM control is normal when the state determination result ErrSt** remains "normal" for Tω / 2 or more.

[0126] Abnormality determination by the difference abnormality determination unit 27b, that is, abnormality determination based on a comparison between the command pulse width Wref** and the output pulse width Wact**, is premised on the command pulse width Wref** being correct, and therefore cannot detect abnormalities that occur up to the generation of the three-phase duty commands Dref_u, Dref_v, and Dref_w on which the command pulse width Wref** is calculated. When the PWM control device 200 is applied to the power conversion device 1000 for operating the electric motor 901 as in the second embodiment, it is necessary to detect abnormalities up to the generation of the three-phase duty commands Dref_u, Dref_v, and Dref_w. In the second embodiment, attention is paid to the fact that, if the PWM control is operating normally, the control commands (including the three-phase duty commands Dref_u, Dref_v, Dref_w) in the control unit 20 will not maintain the same value for more than Tω / 2, and if the output pulse width Wact** of the PWM control signal SW**, which is the output of the control unit 20, maintains the same value for more than Tω / 2, the control command abnormality judgment unit 27e, the on-stuck judgment unit 27g and the off-stuck judgment unit 27h judge that an abnormality has occurred in the control unit 20, such as the stop of calculation of the control commands or memory sticking.

[0127] However, there may be cases where the time variation width of the values ​​of the three-phase duty commands Dref_u, Dref_v, and Dref_w becomes small. In the second embodiment, the three-phase duty commands Dref_u, Dref_v, and Dref_w are generated based on the torque command Trq* input to the control command generating means 21. For example, when the torque command is zero, the value of the generated duty command becomes close to 50%, and may continue to have the same value even if the PWM control is operating normally. In such a case, it is sufficient not to perform an abnormality determination based on the pulse width fixation time FixT** of the output pulse width Wact**. This makes it possible to prevent erroneous detection of an abnormality.

[0128] As described above, the control command abnormality determination unit 27e in the second embodiment determines that "there is a control command abnormality" when the time variation Ref_v is "time variation" and the pulse width fixation time FixT** is Tω / 2 or more. When the torque command Trq* is zero, the time variation Ref_v is "no time variation" and the result is "no control command abnormality" regardless of the pulse width fixation time FixT**. This prevents erroneous detection of an abnormality when the time variation width of the values ​​of the above-mentioned three-phase duty commands Dref_u, Dref_v, and Dref_w becomes small.

[0129] As described above, when the PWM control device of the second embodiment is applied to a power conversion device for operating an electric motor, it is possible to confirm that the PWM control is operating normally without the PWM control signal being stuck. In addition, even when an abnormality such as a stop in the calculation of a control command or memory sticking occurs, it is possible to detect an abnormality in the PWM control. Furthermore, it is possible to appropriately instruct the stop of output of the PWM control signal according to the control states of a plurality of PWM control signals, and to stop the operation of the electric motor at an appropriate timing.

[0130] In the second embodiment, the PWM control signal SW** output from the PWM control device 200 is monitored to obtain the output pulse width of the PWM control signal SW**. Alternatively, the drive signal output from the drive circuit 903 may be monitored to obtain the output pulse width of the drive signal. In this case, the output pulse width of the drive signal is compared with the command pulse width Wref** in the abnormality determination, and an abnormality occurring in the transmission path from the PWM control device 200 to the motor 901 can be detected. In addition, when the state buffer IC or gate driver at the output destination of the microcomputer is broken, the drive signal output from the drive circuit 903 may be stuck. For this reason, by monitoring the drive signal output from the drive circuit 903 and obtaining the output pulse width of the drive signal, it is possible to determine whether the drive signal is stuck.

[0131] In addition, although the power conversion device according to Embodiment 2 has been described assuming an inverter that converts DC power into AC power, the type of the power conversion device is not limited to this, and any power conversion device that includes semiconductor switching elements and converts the output form of power may be used. For example, it may be an AC / DC converter (Alternate Current / Direct Current Converter) that converts AC power into DC power, or a DC / DC converter (Direct Current / Direct Current Converter) that changes the levels of the voltage and current of DC power and outputs them.

[0132] <Operation of PWM Control Device> Next, the operation will be described. FIG. 17 is a flowchart showing the operation of the PWM control device in Embodiment 2. First, the rotation state of the motor 901 is acquired (step ST201: rotation state acquisition step). More specifically, the rotor rotation angle θm of the motor 901 is acquired from the rotation angle sensor 907, and the electrical angle θe and the electrical angle period Tω are calculated based on the rotor rotation angle θm.

[0133] Next, three-phase duty commands Dref_u, Dref_v, and Dref_w as control commands are generated (step ST202: control command generation step).

[0134] Next, six PWM control signals SW** are generated according to the three-phase duty commands Dref_u, Dref_v, and Dref_w (step ST203: control signal generation step).

[0135] Next, the output pulse width Wact** of each of the PWM control signals SW** is acquired (step ST204: output pulse width acquisition step). The acquisition of each output pulse width Wact** is the same as the output pulse width acquisition step described in Embodiment 1.

[0136] Next, six command pulse widths Wref** are calculated based on the three-phase duty commands Dref_u, Dref_v, and Dref_w (step ST205: command pulse width calculation step).

[0137] Next, the presence or absence of an abnormality in the PWM control is determined (step ST206: abnormality determination step). The abnormality determination step will be described in detail later.

[0138] Next, if it is determined in the abnormality determination process that there is an abnormality, that is, if any of the six status determination results ErrSt** is "stuck on abnormality," "stuck off abnormality," or "pulse abnormality," proceed to step ST208, and if it is determined that there is no abnormality, that is, if all six status determination results ErrSt** are "normal," proceed to step ST209 (step ST207).

[0139] If it is determined in the abnormality determination step that there is an abnormality, the generation and output of the PWM control signal SW** is stopped (step ST208: output stop instruction step). As described above, in the second embodiment, the PWM control device 200 is applied to the power conversion device 1000 for operating the electric motor 901, and the output of the PWM control signal SW** is stopped according to the type of abnormality and the switching element in which the abnormality occurs, such as stopping the output of the PWM control signal SW** in a three-phase short-circuit state so as not to regenerate power on the input side. Details of the output stop of the PWM control signal SW** are as described above.

[0140] If it is determined that there is no abnormality in the abnormality determination step, it is determined that the PWM control is operating normally based on the rotation state (electrical angle period Tω) of the electric motor 901 (step ST209: normality determination step). More specifically, if the state in which all six state determination results ErrSt** are "normal" continues for Tω / 2 or more, it is determined that the PWM control is operating normally.

[0141] <Flow of the abnormality judgment process> The abnormality determination process in the embodiment 2 will be described. Fig. 18 is a flow diagram showing the abnormality determination process according to the embodiment 2. First, a difference WDiff** between each output pulse width included in the output pulse width Wact** and each command pulse width included in the command pulse width Wref** is calculated, and each difference WDiff** is compared with a threshold value Dth (step ST2061: pulse width comparison process).

[0142] Next, for each difference included in the difference WDiff**, if the difference is equal to or greater than the threshold Dth, it is determined that there is an abnormality, and if the difference WDiff is less than the threshold Dth, it is determined that there is no abnormality, thereby obtaining a difference anomaly determination result ErrD** as the determination result (step ST2062: difference anomaly determination process).

[0143] Next, for each output pulse width included in the output pulse width Wact**, the time during which the same value continues is measured as the pulse width fixation time FixT** (step ST2063: pulse width fixation time measurement process). When the PWM pulse period is changed, the upper limit value of the output pulse width changes, so the time during which the upper limit value of the output pulse width continues is also measured as the fixation time.

[0144] Next, based on the torque command Trq* output by a higher-level controller or system (not shown), the presence or absence of time fluctuation in the ideal value of the PWM control command (three-phase duty commands Dref_u, Dref_v, Dref_w) is judged, and the presence or absence of time fluctuation Ref_v is obtained as the judgment result (step ST2064: rotation fluctuation judgment process). In the rotation fluctuation judgment process, if the torque command Trq* is zero, it is judged as "no time fluctuation", and if the torque command Trq* is non-zero, it is judged as "there is a time fluctuation".

[0145] Next, the presence or absence of an abnormality in the control command is determined based on the pulse width fixation time FixT**, the electrical angle period Tω, and the presence or absence of time fluctuation Ref_v, and a control command abnormality determination result ErrR** is obtained as a determination result (step ST2065: control command abnormality determination step). In the control command abnormality determination step, if the presence or absence of time fluctuation Ref_v is "with time fluctuation" and the pulse width fixation time FixT** is Tω / 2 or more, it is determined that "there is an abnormality in the control command", and if the above condition is not satisfied, that is, if the presence or absence of time fluctuation Ref_v is "without time fluctuation" or the pulse width fixation time FixT** is less than Tω / 2, it is determined that "there is no abnormality in the control command". As described above, the control command abnormality determination step may not be performed when the rotation speed of the electric motor 901 is equal to or lower than a predetermined rotation speed. In this case, the control command abnormality determination step is performed only when the rotation speed of the electric motor 901 is higher than the predetermined rotation speed.

[0146] Next, the presence or absence of an abnormality is determined based on the difference abnormality determination result ErrD** and the control command abnormality determination result ErrR**, and an abnormality determination result Err** is obtained as the determination result (step ST2066: abnormality presence or absence determination step). In the abnormality presence or absence determination step, it is determined that an abnormality exists when at least one of the difference abnormality determination result ErrD** and the control command abnormality determination result ErrR** exists, and it is determined that no abnormality exists when neither exists. As described above, the difference abnormality determination result ErrD** and the control command abnormality determination result ErrR** each include six determination results corresponding to each switching element of the inverter circuit 902, and therefore the presence or absence of an abnormality is determined for each.

[0147] Next, based on the output pulse width Wact** and the pulse width fixation time FixT**, it is determined whether or not each switching element of the inverter circuit 902 is stuck on ON, and an ON-fixed determination result FixON** is obtained as the determination result (Step ST2067: ON-fixed determination process). In the ON-fixed determination process, if the pulse width fixation time FixT** is equal to or longer than a predetermined time (for example, equal to or longer than Tω / 2) and the output pulse width Wact** is equal to the PWM pulse period, it is determined that the ON-fixed state has occurred.

[0148] Next, based on the output pulse width Wact** and the pulse width fixation time FixT**, it is determined whether or not each switching element of the inverter circuit 902 is stuck in off, and a stuck-off determination result FixOFF** is obtained as the determination result (step ST2068: stuck-off determination step). In the stuck-off determination step, if the pulse width fixation time FixT** is equal to or longer than a predetermined time (for example, equal to or longer than Tω / 2) and the output pulse width Wact** is zero, it is determined that the stuck-off occurs.

[0149] Next, the state of PWM control is judged based on the abnormality judgment result Err**, the stuck-on judgment result FixON**, and the stuck-off judgment result FixOFF**, and a state judgment result ErrSt** is obtained as the judgment result (step ST2069: control state judgment step). As described above, the state judgment result ErrSt** includes "normal", "stuck-on abnormality", "stuck-off abnormality", and "pulse abnormality".

[0150] According to the second embodiment, it is possible to obtain the same effects as those of the first embodiment in a PWM control device applied to a power conversion device that controls an electric motor. In addition, the system is designed to detect abnormalities in the PWM control command based on the motor rotation state and the ideal value of the PWM control command (three-phase duty command).As a result, even if there is an abnormality in the command pulse width and it is not possible to correctly determine an abnormality in the PWM control by comparing only the output pulse width and the command pulse width, the system can detect abnormalities in the PWM control command and correctly determine the abnormality.

[0151] Furthermore, an abnormality is judged for each of the multiple PWM control signals, and when an abnormality is judged and an instruction is given to stop the output of the PWM control signal, the signal level at the time of output stop is set according to the type of abnormality and the PWM control signal in which the abnormality occurred, thereby making it possible to stop the electric motor appropriately.

[0152] Embodiment 3 Next, a third embodiment will be described with reference to Fig. 19 to Fig. 22. In the third embodiment, the configuration of the power conversion device and the overall configuration of the PWM control device are similar to those of the second embodiment, but the implementation of difference anomaly determination in the anomaly determination means is omitted, and the configurations of the control unit and the anomaly determination means are different from those of the second embodiment.

[0153] The configuration and operation of the PWM control device of the third embodiment will be described below, focusing on the differences from the second embodiment. Note that the same or corresponding parts as those of the second embodiment are denoted by the same reference numerals.

[0154] <Control unit function block> 19 is a block diagram showing the configuration of a control unit according to embodiment 3. In the control unit 30, the command pulse width calculation means 23 is omitted from the control unit 20 of embodiment 2. Therefore, the command pulse width Wref** is not input to the abnormality determination means 37.

[0155] The abnormality determination means 37 will be described. FIG. 20 is a block diagram showing the configuration of the abnormality determination means according to the third embodiment. The abnormality determination means 37 is obtained by omitting the pulse width comparison unit 27a and the difference abnormality determination unit 27b from the abnormality determination means 27 according to the second embodiment. The pulse width fixation time measurement unit 27c, the rotation fluctuation determination unit 27d, and the control command abnormality determination unit 27e are the same as those according to the second embodiment. The abnormality presence / absence determination unit 37f determines the presence / absence of an abnormality based only on the control command abnormality determination result ErrR**, and outputs the result to the control state determination unit 27i as the abnormality determination result Err**. The on-stuck determination unit 27g, the off-stuck determination unit 27h, and the control state determination unit 27i are the same as those according to the second embodiment.

[0156] <Operation of the PWM control device> Next, the operation will be described. FIG. 21 is a flowchart showing the operation of the PWM control device according to the third embodiment. As can be seen by comparing FIG. 17 and FIG. 21, in the operation of the PWM control device according to the third embodiment, the command pulse width calculation step is omitted. Steps ST301 to ST304 correspond to steps ST201 to ST204, and steps ST305 to ST308 correspond to steps ST206 to ST209, and each step is the same as that in the second embodiment.

[0157] <Flowchart of the abnormality determination step> The abnormality determination step in the third embodiment will be described. FIG. 22 is a flowchart showing the abnormality determination step according to the third embodiment. As can be seen by comparing FIG. 18 and FIG. 22, in the abnormality determination step according to the third embodiment, only the pulse width comparison step and the difference abnormality determination step are omitted, and steps ST3051 to ST3057 correspond to steps ST2063 to ST2069. For each step, the difference from step ST2066 is that in the abnormality presence / absence determination step of step ST3054, the presence / absence of an abnormality is determined based only on the control command abnormality determination result ErrR**, but the other steps are the same as those in the second embodiment.

[0158] According to the third embodiment, by not performing the determination of the difference abnormality, the calculation of the command pulse width is also omitted. Therefore, while simplifying the configuration compared to the second embodiment, it is possible to detect an abnormality in the PWM control by detecting an abnormality in the PWM control command.

[0159] In addition, in the third embodiment, the output pulse width Wact** is used to determine the abnormality of the control command, as well as the on-sticking and off-sticking. However, it is also conceivable to use the command pulse width Wref** instead of the output pulse width Wact**. In this case, it is necessary to add command pulse width calculation means to the control unit, but the output pulse width acquisition means can be omitted. That is, in the third embodiment, at least one of the output pulse width acquisition means 22 and the command pulse width calculation means 23 may be provided. Regarding the abnormality determination means 37, when using the command pulse width Wref**, the output pulse width Wact** in FIG. 20 may be replaced with the command pulse width Wref**. The same applies to the abnormality determination process.

[0160] Fourth Embodiment. Next, the fourth embodiment will be described with reference to FIGS. 23 and 24. The fourth embodiment is obtained by omitting the on-sticking determination unit and the off-sticking determination unit from the abnormality determination means of the third embodiment. FIG. 23 is a block diagram showing the configuration of the abnormality determination means according to the fourth embodiment. The abnormality determination means 47 omits the on-sticking determination unit 27g and the off-sticking determination unit 27h from the abnormality determination means 37 of the third embodiment. In addition, with the omission of the on-sticking determination unit 27g and the off-sticking determination unit 27h, the on-sticking determination result FixON** and the off-sticking determination result FixOFF** are also eliminated. Therefore, the state determination result ErrSt** has only "abnormality present" or "no abnormality", and is substantially the same as the abnormality determination result Err**. For this reason, the control state determination unit 27i is also omitted, and the presence / absence of abnormality determination unit 47f is configured to output the state determination result ErrSt**.

[0161] <Operation of the PWM control device (flow of the abnormality determination process)> Next, the operation will be described. Since the steps other than the abnormality determination step are the same as those in the third embodiment, only the flow of the abnormality determination step will be described. FIG. 24 is a flow diagram showing the abnormality determination step according to the fourth embodiment. As can be seen by comparing FIG. 22 with FIG. 24, in the abnormality determination step in the fourth embodiment, only the stuck-on determination step, the stuck-off determination step, and the control state determination step are omitted, and steps ST4051 to ST4054 correspond to steps ST3051 to ST3054. However, as described above, in the fourth embodiment, since the state determination result ErrSt** is substantially the same as Err**, the abnormality presence / absence determination step in step ST4054 also includes the control state determination in step ST3057. The other steps are the same as those in the third embodiment.

[0162] According to the fourth embodiment, by omitting the stuck-on judgment and stuck-off judgment, the configuration is further simplified compared to the third embodiment, while an abnormality in PWM control can be detected by detecting an abnormality in the PWM control command.

[0163] In the fourth embodiment, similarly to the third embodiment, it is possible to use a command pulse width Wref** instead of the output pulse width Wact**.

[0164] Although the present application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not exemplified are assumed within the scope of the technology disclosed in this application, including, for example, modifying, adding, or omitting at least one component, and further, extracting at least one component and combining it with a component of another embodiment.

[0165] For example, while the fourth embodiment is configured to only determine whether the control command is abnormal, it is also possible to consider a configuration in which an abnormality in PWM control is detected by determining whether only the control command is stuck on or only the control command is stuck off.

[0166] It is also possible to apply the normal control determination means as in the second embodiment to the first embodiment. In this case, a threshold value for normality determination is separately set, and if the state determination result, which is the result of the abnormality determination, indicates "normal" for a period of time that is equal to or longer than this threshold value, it is determined that the PWM control is operating normally.

[0167] In addition, for the on-sticking determination means and off-sticking determination means as shown in the second and third embodiments, the predetermined time for determining that "on-sticking exists" or "off-sticking exists" does not necessarily need to be based on a value indicating the rotation state of the motor. Therefore, even if the controlled device does not have an electric motor, it is possible to perform on-sticking determination and off-sticking determination. For example, it is possible to add a pulse width fixation time measurement unit, an on-sticking determination unit, and an off-sticking determination unit to the abnormality determination means of the first embodiment. In this case, when it is determined that there is an abnormality in the PWM control from the determination result of the difference abnormality determination, it is determined whether the abnormality is an "on-sticking abnormality" or an "off-sticking abnormality". As described above, when there is an abnormality in the PWM control but there is neither on-sticking nor off-sticking, it is determined as a "pulse abnormality".

[0168] Various aspects of the present disclosure are summarized below as appendices. (Appendix 1) A control command generating means for generating a PWM control command; A control signal generating means for generating a PWM control signal for controlling a controlled device based on the PWM control command; an output pulse width acquisition means for acquiring an output pulse width of the PWM control signal; A command pulse width calculation means for calculating a command pulse width which is a pulse width of the PWM control command; an abnormality determination means for determining whether or not there is an abnormality in PWM control by comparing the output pulse width with the command pulse width, and the output pulse width acquisition means a PWM control device that measures an output pulse width measurement value, which is a measurement value of the width of an output pulse of the PWM control signal, based on edges of the PWM control signal, and when it is determined that an output pulse of the PWM control signal is not present by determining the presence or absence of an output pulse of the PWM control signal, corrects the output pulse width measurement value and sets the corrected output pulse width measurement value as the output pulse width. (Appendix 2) The output pulse width acquisition means an output pulse edge detection unit for detecting the edge; an output pulse width measurement unit that measures the output pulse width measurement value based on the edge; a pulse presence / absence determination unit that determines the presence or absence of an output pulse of the PWM control signal; and an output pulse width correction unit that, when it is determined that there is no output pulse, corrects the output pulse width measurement value and sets the corrected output pulse width measurement value as the output pulse width. (Appendix 3) The output pulse width acquisition means further includes an edge time acquisition unit that acquires a detection time of the edge, 3. The PWM control device according to claim 2, wherein the pulse presence / absence determination unit determines the presence / absence of the output pulse based on a difference between a final edge detection time, which is the time when the edge was last detected, and a current time. (Appendix 4) The output pulse width acquisition means further includes a signal level acquisition unit that acquires a signal level of the PWM control signal, 4. The PWM control device according to claim 3, wherein the output pulse width correction unit corrects the output pulse width measurement value based on a signal level of the PWM control signal at the final edge detection time. (Appendix 5) The control signal generating means generates the PWM control signal according to a PWM pulse period; The PWM control device according to claim 4, wherein the output pulse width correction unit corrects the output pulse width measurement value to the PWM pulse period when the signal level of the PWM control signal at the final edge detection time is "high", and corrects the output pulse width measurement value to zero when the signal level of the PWM control signal at the final edge detection time is "low". (Appendix 6) The control signal generating means generates the PWM control signal according to a PWM pulse period; 5. The PWM control device according to claim 3, wherein the pulse presence / absence determining unit determines that the output pulse is absent when a difference between a current time and the final edge detection time is equal to or greater than the PWM pulse period. (Appendix 7) The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control device further includes a rotation state acquisition means for acquiring a rotation state of the electric motor, The PWM control device according to any one of Appendices 1 to 6, wherein the abnormality determination means has a pulse width fixation time measurement unit that measures a pulse width fixation time, which is a time during which the output pulse width or the command pulse width continues to have a constant value, and determines whether or not there is an abnormality in the PWM control based on a comparison between the time determined based on the rotation state and the pulse width fixation time, and based on whether or not there is a time fluctuation in the ideal value of the PWM control command. (Appendix 8) the rotation state acquisition means acquires at least an electrical angle period of the electric motor; 8. The PWM control device according to claim 7, wherein the abnormality determination means determines that there is an abnormality in the PWM control when there is a time fluctuation in the ideal value and the pulse width fixation time is equal to or longer than half of the electrical angle period. (Appendix 9) a pulse width fixation time measurement unit that measures a pulse width fixation time, which is a time during which the output pulse width or the command pulse width continues to have a constant value; When the abnormality determination means determines that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 7. The PWM control device according to claim 1, wherein the PWM control abnormality is determined to be a stuck-on abnormality when the constant value is a PWM pulse period, and the PWM control abnormality is determined to be a stuck-off abnormality when the constant value is zero. (Appendix 10) The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control device is A rotation state acquisition means for acquiring a rotation state of the electric motor; A normal control determination means for determining whether or not the PWM control by the PWM control device is operating normally is further provided, The PWM control device according to any one of claims 1 to 6, wherein the normal control determination means determines that the PWM control is operating normally when the determination result of the abnormality determination means indicates that there is no abnormality for a period of time determined based on the rotation state or longer. (Appendix 11) 11. The PWM control device according to claim 10, wherein the rotation state acquisition means acquires at least an electrical angle period of the motor, and the time determined based on the rotation state is half the electrical angle period. (Appendix 12) 12. The PWM control device according to any one of claims 1 to 11, further comprising an output stop instruction means for instructing the control signal generating means to stop outputting the PWM control signal when the abnormality determination means determines that there is an abnormality in the PWM control by the PWM control device. (Appendix 13) the control signal generating means generates a plurality of the PWM control signals; 13. The PWM control device according to claim 12, wherein the output stop instruction means sets a signal level of each of the PWM control signals when output of each of the PWM control signals is to be stopped in response to an abnormality in each of the PWM control signals. (Appendix 14) A PWM control device that outputs a PWM control signal to a controlled device having an electric motor that is operated by being supplied with power according to the PWM control signal, A control command generating means for generating a PWM control command; a control signal generating means for generating the PWM control signal based on the PWM control command; At least one of an output pulse width acquisition means for acquiring an output pulse width of the PWM control signal and a command pulse width calculation means for calculating a command pulse width which is a pulse width of the PWM control command; An abnormality determination means for determining whether or not there is an abnormality in the PWM control; A rotation state acquisition means for acquiring a rotation state of the electric motor, the abnormality determination means has a pulse width fixation time measurement unit that measures a pulse width fixation time, which is the time during which the output pulse width or the command pulse width continues to have a constant value, and determines whether or not there is an abnormality in the PWM control based on a comparison between the time determined based on the rotation state and the pulse width fixation time, and based on whether or not there is a time fluctuation in the ideal value of the PWM control command. (Appendix 15) When the abnormality determination means determines that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 15. The PWM control device according to claim 14, wherein the abnormality in the PWM control is determined to be a stuck-on abnormality when the constant value is a PWM pulse period, and the abnormality in the PWM control is determined to be a stuck-off abnormality when the constant value is zero. (Appendix 16) A control command generating step of generating a PWM control command; a control signal generating step of generating a PWM control signal for controlling a controlled device based on the PWM control command; an output pulse width acquisition step of acquiring an output pulse width of the PWM control signal; A command pulse width calculation step of calculating a command pulse width which is a pulse width of the PWM control command; and an abnormality determination step of determining whether or not there is an abnormality in PWM control by comparing the output pulse width with the command pulse width, wherein in the output pulse width acquisition step, a PWM control method comprising: measuring an output pulse width measurement value, which is a measurement value of the width of an output pulse of the PWM control signal, based on edges of the PWM control signal; and, when it is determined by determining whether or not an output pulse of the PWM control signal is present, correcting the output pulse width measurement value and setting the corrected output pulse width measurement value as the output pulse width. (Appendix 17) The output pulse width acquisition step includes an output pulse edge detection step of detecting the edge. an output pulse width measuring step of measuring the output pulse width measurement value based on the edge; an output pulse presence / absence determination step of determining whether or not an output pulse of the PWM control signal is present; and when it is determined that there is no output pulse, correcting the output pulse width measurement value and setting the corrected output pulse width measurement value as the output pulse width. (Appendix 18) The output pulse width acquisition step further includes an edge time acquisition step of acquiring a detection time of the edge, 18. The PWM control method according to claim 17, wherein in the output pulse presence / absence determining step, the presence / absence of the output pulse is determined based on the difference between a final edge detection time, which is the time when the edge was last detected, and a current time. (Appendix 19) The output pulse width acquisition step further includes a signal level acquisition step of acquiring a signal level of the PWM control signal, 19. The PWM control method according to claim 18, wherein in the output pulse width correcting step, the output pulse width measured value is corrected based on a signal level of the PWM control signal at the final edge detection time. (Appendix 20) In the control signal generating step, the PWM control signal is generated according to a PWM pulse period; 20. The PWM control method according to claim 19, wherein, in the output pulse width correcting step, if the signal level of the PWM control signal at the final edge detection time is "high", the output pulse width measurement value is corrected to the PWM pulse period, and if the signal level of the PWM control signal at the final edge detection time is "low", the output pulse width measurement value is corrected to zero. (Appendix 21) In the control signal generating step, the PWM control signal is generated according to a PWM pulse period; 20. The PWM control method according to claim 18, wherein in the output pulse presence / absence determining step, it is determined that the output pulse is absent if the difference between the current time and the final edge detection time is equal to or greater than the PWM pulse period. (Appendix 22) The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control method further includes a rotation state acquisition step of acquiring a rotation state of the electric motor, 22. The PWM control method according to any one of Appendices 16 to 21, wherein, in the abnormality determination step, a pulse width fixation time, which is a time during which the output pulse width or the command pulse width continues to have a constant value, is measured, and the presence or absence of an abnormality in the PWM control is determined based on a comparison between the pulse width fixation time and a time determined based on the rotation state, and based on the presence or absence of a time fluctuation in the ideal value of the PWM control command. (Appendix 23) In the rotation state acquisition step, at least an electrical angle period of the electric motor is acquired, 23. The PWM control method according to claim 22, wherein, in the abnormality determination step, if there is a time fluctuation of the ideal value and the pulse width fixation time is equal to or longer than half of the electrical angle period, it is determined that there is an abnormality in the PWM control. (Appendix 24) measuring a pulse width fixation time during which the output pulse width or the command pulse width continues to have a constant value; When it is determined in the abnormality determination step that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 22. The PWM control method according to claim 16, wherein the PWM control abnormality is determined to be a stuck-on abnormality when the constant value is a PWM pulse period, and the PWM control abnormality is determined to be a stuck-off abnormality when the constant value is zero. (Appendix 25) The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control method includes: a rotation state acquisition step of acquiring a rotation state of the electric motor; A normal control determination step of determining whether or not the PWM control according to the PWM control method is operating normally is further provided, 22. The PWM control method according to any one of claims 16 to 21, wherein in the normal control determination step, if the determination result in the abnormality determination step that there is no abnormality continues for a time period determined based on the rotation state or longer, it is determined that the PWM control is operating normally. (Appendix 26) 26. The PWM control method according to claim 25, wherein, in the rotation state acquisition step, at least an electrical angle period of the motor is acquired, and the time determined based on the rotation state is half the electrical angle period. (Appendix 27) The PWM control method according to any one of claims 16 to 26, wherein, when it is determined in the abnormality determination step that there is an abnormality in the PWM control performed by the PWM control method, output of the PWM control signal is stopped. (Appendix 28) A plurality of the PWM control signals are generated in the control signal generating step; 28. The PWM control method according to claim 27, wherein when stopping the output of the PWM control signals, the signal levels of the respective PWM control signals are set in accordance with an abnormality in the respective PWM control signals. (Appendix 29) A PWM control method for outputting a PWM control signal to a controlled device having an electric motor that is operated by being supplied with power according to the PWM control signal, comprising: A control command generating step of generating a PWM control command; a control signal generating step of generating the PWM control signal based on the PWM control command; At least one of an output pulse width acquisition step of acquiring an output pulse width of the PWM control signal and a command pulse width calculation step of calculating a command pulse width which is a pulse width of the PWM control command; an abnormality determination step for determining whether or not there is an abnormality in the PWM control; A rotation state acquisition step of acquiring a rotation state of the electric motor, a pulse width fixation time, which is the time during which the output pulse width or the command pulse width continues to be a constant value, is measured in the abnormality determination step, and the presence or absence of an abnormality in the PWM control is determined based on a comparison between the pulse width fixation time and a time determined based on the rotation state, and based on the presence or absence of a time fluctuation in the ideal value of the PWM control command. (Appendix 30) When it is determined in the abnormality determination step that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 30. The PWM control method according to claim 29, wherein the abnormality in the PWM control is determined to be a stuck-on abnormality when the constant value is a PWM pulse period, and the abnormality in the PWM control is determined to be a stuck-off abnormality when the constant value is zero. [Explanation of symbols]

[0169] 10, 20, 30 control unit, 11, 21 control command generating means, 11a, 21e duty command calculating unit, 12, 22 output pulse width acquiring means, 12a output pulse edge detecting unit, 12b output pulse width measuring unit, 12c edge time acquiring unit, 12d pulse presence / absence determining unit, 12e signal level acquiring unit, 12f output pulse width correcting unit, 13, 23 command pulse width calculating means, 17, 27, 37, 47 abnormality determining means, 17a, 27a pulse width comparing unit, 17b, 27b difference abnormality determining unit, 18, 28 output stop instruction means, 19, 29 control signal generating means, 25 rotation state acquiring means, 25b electrical angle period calculating unit, 27c pulse width fixation time measuring unit, 27e control command abnormality determining unit, 27f, 37f, 47f abnormality determining unit, 27g ON-stuck determination unit, 27h OFF-stuck determination unit, 100, 200 PWM control device, 900 controlled device, 901 electric motor, Dref duty command, Dref_u, Dref_v, Dref_w three-phase duty command, EdgLev signal level, EdgR pulse presence / absence determination result, EdgT edge time, ErrSt, ErrSt** state determination result, FixT** pulse width fixation time, Ft final edge detection time, Pt current time, Stp stop command signal, SW, SW_UH, SW_VH, SW_WH, SW_UL, SW_VL, SW_WL, SW** PWM control signal, Tω electrical angle period, Wact, Wact** output pulse width, Wref, Wref** command pulse width, Wmon output pulse width measurement value

Claims

1. A control command generating means for generating a PWM control command; A control signal generating means for generating a PWM control signal for controlling a controlled device based on the PWM control command; an output pulse width acquisition means for acquiring an output pulse width of the PWM control signal; a command pulse width calculation means for calculating a command pulse width which is a pulse width of the PWM control command; an abnormality determination means for determining whether or not there is an abnormality in PWM control by comparing the output pulse width with the command pulse width, and the output pulse width acquisition means a PWM control device that measures an output pulse width measurement value, which is a measurement value of the width of an output pulse of the PWM control signal, based on edges of the PWM control signal, and when it is determined by determining the presence or absence of an output pulse of the PWM control signal that the output pulse is not present, corrects the output pulse width measurement value and sets the corrected output pulse width measurement value as the output pulse width.

2. The output pulse width acquisition means an output pulse edge detection unit for detecting the edge; an output pulse width measurement unit that measures the output pulse width measurement value based on the edge; a pulse presence / absence determination unit that determines the presence or absence of an output pulse of the PWM control signal; 2. The PWM control device according to claim 1, further comprising an output pulse width correction unit that corrects the output pulse width measurement value when it is determined that the output pulse is not present, and sets the corrected output pulse width measurement value as the output pulse width.

3. The output pulse width acquisition means further includes an edge time acquisition unit that acquires a detection time of the edge, 3. The PWM control device according to claim 2, wherein the pulse presence / absence determining unit determines the presence / absence of the output pulse based on a difference between a last edge detection time, which is the time when the edge was last detected, and a current time.

4. The output pulse width acquisition means further includes a signal level acquisition unit that acquires a signal level of the PWM control signal, 4. The PWM control device according to claim 3, wherein the output pulse width correction unit corrects the output pulse width measurement value based on the signal level of the PWM control signal at the final edge detection time.

5. The control signal generating means generates the PWM control signal according to a PWM pulse period; 5. The PWM control device according to claim 4, wherein the output pulse width correction unit corrects the output pulse width measurement value to the PWM pulse period when the signal level of the PWM control signal at the final edge detection time is "high", and corrects the output pulse width measurement value to zero when the signal level of the PWM control signal at the final edge detection time is "low".

6. The control signal generating means generates the PWM control signal according to a PWM pulse period; 5. The PWM control device according to claim 3, wherein the pulse presence / absence determining unit determines that the output pulse is absent when a difference between a current time and the final edge detection time is equal to or greater than the PWM pulse period.

7. The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control device further includes a rotation state acquisition means for acquiring a rotation state of the electric motor, 6. The PWM control device according to claim 1, wherein the abnormality determination means has a pulse width fixation time measurement unit that measures a pulse width fixation time, which is a time during which the output pulse width or the command pulse width continues to have a constant value, and determines whether or not there is an abnormality in the PWM control based on a comparison between the time determined based on the rotation state and the pulse width fixation time, and based on whether or not there is a time fluctuation in the ideal value of the PWM control command.

8. the rotation state acquisition means acquires at least an electrical angle period of the electric motor; 8. The PWM control device according to claim 7, wherein the abnormality determination means determines that there is an abnormality in the PWM control when there is a time variation in the ideal value and the pulse width fixation time is equal to or longer than half of the electrical angle period.

9. a pulse width fixation time measurement unit that measures a pulse width fixation time, which is a time during which the output pulse width or the command pulse width continues to have a constant value; When the abnormality determination means determines that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 6. The PWM control device according to claim 1, wherein when the constant value is a PWM pulse period, the abnormality in the PWM control is determined to be an on-stuck abnormality, and when the constant value is zero, the abnormality in the PWM control is determined to be an off-stuck abnormality.

10. The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control device includes: A rotation state acquisition means for acquiring a rotation state of the electric motor; A normal control determination means for determining whether or not the PWM control by the PWM control device is operating normally, 6. The PWM control device according to claim 1, wherein the normal control determination means determines that the PWM control is operating normally when the state in which the determination result of the abnormality determination means is no abnormality continues for a time period determined based on the rotation state or longer.

11. 11. The PWM control device according to claim 10, wherein the rotation state acquisition means acquires at least an electrical angle period of the electric motor, and the time determined based on the rotation state is half the electrical angle period.

12. 6. The PWM control device according to claim 1, further comprising an output stop instruction means for instructing the control signal generating means to stop outputting the PWM control signal when the abnormality determination means determines that there is an abnormality in the PWM control by the PWM control device.

13. The control signal generating means generates a plurality of the PWM control signals, 13. The PWM control device according to claim 12, wherein the output stop instruction means sets a signal level of each of the PWM control signals when output of each of the PWM control signals is to be stopped in response to an abnormality in each of the PWM control signals.

14. A PWM control device that outputs a PWM control signal to a controlled device having an electric motor that is operated by being supplied with power according to the PWM control signal, A control command generating means for generating a PWM control command; a control signal generating means for generating the PWM control signal based on the PWM control command; at least one of an output pulse width acquisition means for acquiring an output pulse width of the PWM control signal and a command pulse width calculation means for calculating a command pulse width which is a pulse width of the PWM control command; An abnormality determination means for determining whether or not there is an abnormality in the PWM control; A rotation state acquisition means for acquiring a rotation state of the electric motor, the abnormality determination means has a pulse width fixation time measurement unit that measures a pulse width fixation time, which is the time during which the output pulse width or the command pulse width continues to have a constant value, and determines whether or not there is an abnormality in the PWM control based on a comparison between the time determined based on the rotation state and the pulse width fixation time, and based on whether or not there is a time fluctuation in the ideal value of the PWM control command.

15. When the abnormality determination means determines that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 15. The PWM control device according to claim 14, wherein when the constant value is a PWM pulse period, the abnormality in the PWM control is determined to be a stuck-on abnormality, and when the constant value is zero, the abnormality in the PWM control is determined to be a stuck-off abnormality.

16. a control command generating step of generating a PWM control command; a control signal generating step of generating a PWM control signal for controlling a controlled device based on the PWM control command; an output pulse width acquisition step of acquiring an output pulse width of the PWM control signal; a command pulse width calculation step of calculating a command pulse width which is a pulse width of the PWM control command; and an abnormality determination step of determining whether or not there is an abnormality in PWM control by comparing the output pulse width with the command pulse width, wherein in the output pulse width acquisition step, a PWM control method comprising: measuring an output pulse width measurement value, which is a measurement value of the width of an output pulse of the PWM control signal, based on edges of the PWM control signal; and, when it is determined by determining the presence or absence of an output pulse of the PWM control signal that the output pulse is not present, correcting the output pulse width measurement value and setting the corrected output pulse width measurement value as the output pulse width.

17. The output pulse width acquisition step includes an output pulse edge detection step of detecting the edge. an output pulse width measuring step of measuring the output pulse width measurement value based on the edge; an output pulse presence / absence determination step of determining whether or not an output pulse of the PWM control signal is present; The PWM control method according to claim 16, further comprising an output pulse width correcting step of correcting the output pulse width measurement value when it is determined that there is no output pulse, and setting the corrected output pulse width measurement value as the output pulse width.

18. The output pulse width acquisition step further includes an edge time acquisition step of acquiring a detection time of the edge, 18. The PWM control method according to claim 17, wherein in the output pulse presence / absence determining step, the presence / absence of the output pulse is determined based on a difference between a last edge detection time, which is the time when the edge was last detected, and a current time.

19. the output pulse width acquiring step further includes a signal level acquiring step of acquiring a signal level of the PWM control signal, 20. The PWM control method according to claim 18, wherein in the output pulse width correcting step, the output pulse width measurement value is corrected based on a signal level of the PWM control signal at the final edge detection time.

20. In the control signal generating step, the PWM control signal is generated according to a PWM pulse period; 20. The PWM control method according to claim 19, wherein, in the output pulse width correcting step, when the signal level of the PWM control signal at the final edge detection time is "high", the output pulse width measurement value is corrected to the PWM pulse period, and when the signal level of the PWM control signal at the final edge detection time is "low", the output pulse width measurement value is corrected to zero.

21. In the control signal generating step, the PWM control signal is generated according to a PWM pulse period; 20. The PWM control method according to claim 18, wherein in the output pulse presence / absence determining step, it is determined that the output pulse is absent when a difference between the current time and the final edge detection time is equal to or greater than the PWM pulse period.

22. The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control method further includes a rotation state acquisition step of acquiring a rotation state of the electric motor, 21. The PWM control method according to claim 16, wherein in the abnormality determination step, a pulse width fixation time, which is a time during which the output pulse width or the command pulse width continues to have a constant value, is measured, and the presence or absence of an abnormality in the PWM control is determined based on a comparison between the pulse width fixation time and a time determined based on the rotation state, and based on the presence or absence of a time fluctuation in the ideal value of the PWM control command.

23. In the rotation state acquisition step, at least an electrical angle period of the electric motor is acquired, 23. The PWM control method according to claim 22, wherein, in the abnormality determination step, it is determined that there is an abnormality in the PWM control when there is a time fluctuation of the ideal value and the pulse width fixation time is equal to or longer than half of the electrical angle period.

24. measuring a pulse width fixation time during which the output pulse width or the command pulse width continues to have a constant value; When it is determined in the abnormality determination step that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 21. The PWM control method according to claim 16, wherein when the constant value is a PWM pulse period, the abnormality in the PWM control is determined to be an ON-stuck abnormality, and when the constant value is zero, the abnormality in the PWM control is determined to be an OFF-stuck abnormality.

25. The controlled device has an electric motor that is supplied with power in response to the PWM control signal and operates, The PWM control method includes: a rotation state acquisition step of acquiring a rotation state of the electric motor; and a normal control determination step of determining whether or not the PWM control according to the PWM control method is operating normally.

21. The PWM control method according to claim 16, wherein in the normal control determination step, if the determination result in the abnormality determination step that there is no abnormality continues for a time period determined based on the rotation state or longer, it is determined that the PWM control is operating normally.

26. 26. The PWM control method according to claim 25, wherein in the rotation state obtaining step, at least an electrical angle period of the motor is obtained, and the time determined based on the rotation state is half the electrical angle period.

27. 21. The PWM control method according to claim 16, wherein, when it is determined in the abnormality determination step that there is an abnormality in the PWM control performed by the PWM control method, output of the PWM control signal is stopped.

28. A plurality of the PWM control signals are generated in the control signal generating step; 28. The PWM control method according to claim 27, further comprising the step of: setting a signal level of each of the PWM control signals in response to an abnormality in each of the PWM control signals when the output of the PWM control signals is stopped.

29. A PWM control method for outputting a PWM control signal to a controlled device having an electric motor that is operated by being supplied with power according to the PWM control signal, comprising: a control command generating step of generating a PWM control command; a control signal generating step of generating the PWM control signal based on the PWM control command; At least one of an output pulse width acquisition step of acquiring an output pulse width of the PWM control signal and a command pulse width calculation step of calculating a command pulse width which is a pulse width of the PWM control command; an abnormality determination step of determining whether or not there is an abnormality in the PWM control; A rotation state acquisition step of acquiring a rotation state of the electric motor, a pulse width fixation time, which is the time during which the output pulse width or the command pulse width continues to have a constant value, is measured in the abnormality determination step, and the presence or absence of an abnormality in the PWM control is determined based on a comparison between the pulse width fixation time and a time determined based on the rotation state, and based on the presence or absence of a time fluctuation in the ideal value of the PWM control command.

30. When it is determined in the abnormality determination step that there is an abnormality in the PWM control and the pulse width fixation time is equal to or longer than a predetermined time, 30. The PWM control method according to claim 29, wherein the abnormality in the PWM control is determined to be a stuck-on abnormality when the constant value is a PWM pulse period, and the abnormality in the PWM control is determined to be a stuck-off abnormality when the constant value is zero.

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