JP2008048504A - Controller for three-phase rotary machines - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for three-phase rotary machines wherein a current passing through a three-phase rotary machine can be appropriately acquired by taking in the output of a sensing means for sensing a current passing through the switching elements on the upper arm or the lower arm of an inverter. <P>SOLUTION: Shunt resistors Ru, Rv, Rw are connected in series with the switching elements 14, 18, 22 on the lower arm of the inverter 10. The current passed through a motor 4 is acquired by the amounts ru, rv, rw of voltage drop due to them. When a period for which all of the switching elements 14, 18, 22 are on is short, any of the switching elements 14, 18, 22 is held in on state to extend the period. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In order to control the output of the three-phase rotating machine, the present invention takes in the output of the sensing means that senses the current flowing through the switching elements on the upper and lower stages of the inverter arm and makes the output of the three-phase rotating machine desired. The present invention relates to a control device for a three-phase rotating machine that operates the inverter by pulse width modulation based on a comparison between a three-phase signal wave for control and a carrier wave.

  A control device for a three-phase motor that controls the amount of current flowing in the three-phase by pulse width modulation (PWM) to control the output of the three-phase motor as desired is well known. That is, on the basis of a comparison between the three-phase command voltage (signal wave) and the triangular carrier wave, the current flowing in the three-phase motor is controlled by turning on / off the switching element of the inverter. Here, the command voltage is normally calculated sequentially based on the required torque for the three-phase motor and the current flowing through the three-phase motor. A current sensor is usually used as a sensor for sensing the current flowing through the three-phase motor.

  By the way, in recent years, it has been proposed to use a shunt resistor connected in series to each upper or lower switching element of the inverter arm in order to reduce the size of the means for sensing the current flowing through the three-phase motor and simplify the structure. ing. According to this, as compared with the case of using a current sensor, the means for sensing current can be reduced in size and simplified.

  However, for example, when a shunt resistor is connected in series to each switching element in the lower stage of the arm, currents in all three phases can be sensed only during the generation period of the voltage vector V0 in which the lower switching elements in all phases are on. Therefore, the timing for taking in the voltage drop amount (current equivalent value) due to the shunt resistor is limited.

  Further, immediately after the voltage vector V0 generation period is reached, current ringing is large, so that current acquisition based on the voltage drop amount of the shunt resistor cannot be appropriately performed. Since the voltage vector V0 generation period decreases as the modulation rate by the PWM control increases as the command voltage increases, it is particularly difficult to acquire current during the voltage vector V0 generation period at a high modulation rate. Incidentally, as another control device for a three-phase rotating machine that acquires a current based on a shunt resistance, for example, there is one described in Patent Document 1 below.

It should be noted that the present invention is not limited to the one using the shunt resistor, and the one that acquires the current flowing through the three-phase rotating machine by taking in the output of the sensing means that senses the current flowing through the upper and lower switching elements of the inverter arm. In fact, such a situation that it is difficult to acquire a three-phase current is also generally common.
JP 2005-160147 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a three-phase rotating machine by taking in an output of a sensing means for sensing a current flowing through each switching element in an upper stage or a lower stage of an inverter arm. It is an object to provide a control device for a three-phase rotating machine that can appropriately acquire the current flowing through the motor.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  The invention according to claim 1 is characterized in that the carrier wave is selectively expanded to selectively extend either the period in which the two phases on the sensing means side of the switching element of the inverter are in the on state or the period in which the three phases are in the on state. By correcting the signal wave to be compared with the one-phase switching of the upper or lower stage of the inverter arm while maintaining the relative magnitude relationship between the signal waves over one period of the carrier wave A fixing means for fixing the element in an ON state, and an acquisition means for acquiring an electric current flowing through the three-phase rotating machine by capturing an output of the sensing means within the selectively expanded period. And

  In the above configuration, during the period when the three-phase switching element on the sensing means side is in the ON state, a three-phase current can be acquired based on the three outputs from the sensing means. Further, during the period in which the two-phase switching element on the sensing means side is in the ON state, a three-phase current can be obtained by using Kirchhoff's law based on two outputs from the sensing means. However, any of these periods can be shortened depending on the relationship between the three-phase signal wave and the carrier wave. When these periods are short, it becomes difficult to obtain an appropriate value as a three-phase current due to current ringing accompanying the start of the period. In this regard, in the above configuration, the period is expanded while maintaining the relative magnitude relationship between the signal waves. For this reason, it is possible to capture the output of the sensing means at a timing when the ringing is sufficiently attenuated while the current flowing through each phase of the rotating machine is set to a desired current assumed by the signal wave before correction. Therefore, an appropriate value can be acquired as the current flowing through the three phases.

  According to a second aspect of the present invention, in the first aspect of the invention, the carrier wave is a triangular wave having substantially the same ascending speed and descending speed, and the acquisition means is provided each time the carrier wave is near an upper limit value or a lower limit value. The output of the sensing means is captured.

  In the above configuration, the carrier wave has a substantially line symmetrical waveform with respect to the upper limit value and the lower limit value. For this reason, the operation mode of the switching element determined based on the comparison between the carrier wave and the signal wave is substantially symmetric with respect to the upper limit value and the lower limit value of the carrier wave. For this reason, the current flowing through the three phases in the vicinity of the upper limit value or the lower limit value of the carrier wave is substantially equal to the average value of the three-phase currents in the period of the carrier wave. In the above configuration, paying attention to this point, it is possible to easily obtain information on the average value of the current within the period of the carrier wave by capturing the output of the sensing means in the vicinity of the upper limit value or the lower limit value of the carrier wave.

  The invention according to claim 3 is the invention according to claim 2, wherein the signal wave is updated each time the carrier wave is near an upper limit value or near a lower limit value. The output of the sensing means is captured in the vicinity of an intermediate point in the update cycle.

  In the above configuration, since the signal wave is updated every time the carrier wave is near the upper limit value or near the lower limit value, the operation mode of the switching element determined based on the comparison between the carrier wave and the signal wave is at the intermediate point of the signal wave update cycle. On the other hand, it has a suitable symmetry. For this reason, the output of the sensing means at the intermediate point in the update period of the signal wave can be a value corresponding to the average value of the three-phase currents in the update period with high accuracy.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the fixing means fixes the one-phase switching element on the sensing means side to the on state, thereby fixing the one on the sensing means side. When the period during which the switching elements are in the all-phase ON state is equal to or greater than the threshold, the one-phase switching element on the sensing means side is fixed to the ON state.

  In the above configuration, when the period in which the three phases of the switching element on the sensing means side are in the ON state is equal to or greater than the threshold when the signal wave is corrected, the period in which the three phases are in the ON state is expanded. As a result, in the case of capturing the output of the sensing means when the three phases on the sensing means side are turned on, the influence of ringing caused by the three phases being turned on is sufficiently suppressed. Can be quantified by a threshold.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the fixing means includes a period in which the three phases on the sensing means side determined by a comparison between a signal wave to be corrected and the carrier wave are in an on state and an off state. When the sum in one period of the carrier wave for a period to be in a state is equal to or greater than a threshold value, the one-phase switching element on the sensing means side is fixed to the on state, and when the sum is less than the threshold value, the sensing means The one-phase switching element which is not on the side is fixed in the ON state.

  By fixing the one-phase switching element on the sensing means side to the ON state, the signal wave to be corrected and the carrier wave are in a period during which the switching element on the sensing means side is in the ON state in one cycle of the carrier wave. It is the sum of the period when the three phases on the sensing means side determined by the comparison are in the on state and the period when the three phases are determined by the comparison. In the above configuration, paying attention to this point, based on the above sum, the one-phase switching element on the sensing means side is fixed to the on state, so that the switching element on the sensing means side is in the all-phase on state within one cycle of the carrier wave. And a threshold value can be compared.

  Then, based on the comparison with the threshold value, the one-phase switching element on the sensing means side or the one-phase switching element not on the sensing means side is fixed to the on state, so that the three-phase or two-phase switching element on the sensing means side is The period during which the on state is maintained can be extended.

  According to a sixth aspect of the present invention, in the invention according to the fourth or fifth aspect, the threshold value is a period in which the two phases on the sensing means side determined by a comparison between the signal wave to be corrected and the carrier wave are in an ON state. It is characterized by being.

  In the above configuration, the threshold value is a period in which the two phases on the sensing means side are in the ON state under the assumption that the signal wave is not corrected. Therefore, by fixing the one-phase switching element on the sensing means side to the ON state, when the period during which the switching element on the sensing means side is in the ON state is less than the threshold value within one cycle of the carrier wave, Taking in the output of the sensing means during the period in which the three phases are in the on state is shorter than the period in which the two phases on the sensing means side are in the on state under the assumption that no correction is performed. It can be judged that it is not desirable from the viewpoint of suppression. For this reason, in the above configuration, it is possible to capture the output of the sensing means by preferentially using the period in which the three phases are turned on while suppressing the influence of ringing as much as possible.

  According to a seventh aspect of the present invention, in the invention according to the fourth or fifth aspect, the threshold value is a ringing of a current flowing through the three phases generated when the three-phase switching element on the sensing means side is turned on. It is characterized by being set to be longer than the settling time.

  In the above configuration, the ringing associated with the three phases being turned on is sufficiently attenuated during the period in which the three phases on the sensing means side are turned on. For this reason, the influence of ringing can be suppressed as much as possible when capturing the output of the sensing means during the period in which the three phases are in the ON state.

  According to an eighth aspect of the present invention, in the invention according to any one of the first to seventh aspects, a period during which the sensing element side switching element is turned on in the three-phase signal waves to be corrected by the fixing means. Based on the value of the signal wave of the shortest phase, further comprising a determination means for determining whether or not to correct the signal wave by the fixing means, the acquisition means when the correction is not made, Of the switching elements, the output of the sensing means is taken in either the period in which the two phases on the sensing means side are in the on state or the period in which the three phases are in the on state.

  When the one-phase switching element is fixed over one period of the carrier by the fixing means, the number of ON / OFF operations of the switching element within one period of the carrier is reduced. For this reason, compared with the case where it does not fix by a fixing means, the fluctuation amount of the electric current which flows through 3 phases becomes large.

  On the other hand, among the three-phase signal waves to be corrected, the period in which the three-phase is turned on when there is no correction is determined by the value of the signal wave of the shortest phase in which the switching element on the sensing means side is turned on. I can grasp it. For this reason, whether or not the period during which the three phases are in the ON state when there is no correction can sufficiently suppress the influence of ringing when capturing the output of the sensing means, depending on the value of the signal wave. Can be judged. In the above configuration, when the influence of the ringing can be sufficiently suppressed, the influence of the ringing at the time of taking in the output of the sensing means is suppressed by not fixing the switching element by the fixing means. However, the fluctuation amount of the current flowing through the three phases can be suppressed as much as possible.

  According to a ninth aspect of the present invention, in the invention according to the eighth aspect of the present invention, the determination means performs a three-phase switching on the sensing means side during a period in which the switching element on the sensing means side in the shortest phase is turned on. It is determined that the correction is performed when it is less than a settling time for ringing of the current flowing through the three phases that occurs when the element is turned on.

  As described above, it is possible to grasp the period in which the three-phase switching element on the sensing means side is turned on by performing no correction from the period in which the switching element on the sensing means side is turned on in the shortest phase. . Then, when the period during which the switching element on the sensing means side in the shortest phase is in the ON state is equal to or shorter than the settling time, the correction is performed, and the detection is performed during the period in which the three phases are in the ON state because no correction is performed. Even when the output of the means is taken in, the influence of ringing can be avoided.

(First embodiment)
Hereinafter, a first embodiment in which a control device for a three-phase rotating machine according to the present invention is applied to a control device for a three-phase rotating machine mounted on a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of an electric motor and its control system mounted on the hybrid vehicle.

  As illustrated, an inverter 10 is connected to three phases (U phase, V phase, and W phase) of the electric motor 4. This inverter 10 is a three-phase inverter, and switching elements 12 and 14 (U-phase arm) and switching elements 16 and 18 (V-phase) are connected to electrically connect each of the three phases to the positive electrode side or the negative electrode side of the battery 7. Arm) and switching elements 20 and 22 (W-phase arm) in parallel. Furthermore, the inverter 10 includes flywheel diodes 24 to 34 connected in antiparallel to the switching elements 12 to 22. A connection point for connecting the switching element 12 and the switching element 14 in series is connected to the U phase of the electric motor 4. A connection point for connecting the switching element 16 and the switching element 18 in series is connected to the V phase of the motor 4. Furthermore, a connection point for connecting the switching element 20 and the switching element 22 in series is connected to the W phase of the electric motor 4. Incidentally, these switching elements 12-22 are comprised by the insulated gate bipolar transistor (IGBT) in this embodiment.

  A smoothing capacitor 40 is connected to both ends of each pair of switching elements 12 and 14, switching elements 16 and 18, and switching elements 20 and 22 of the inverter 10.

  The electric motor 4 is provided with a position sensor 42 for detecting the rotation angle θ of the output shaft. On the other hand, a shunt resistor Ru for sensing a current flowing through the switching element 14 is connected in series with the switching element 14 between the low potential side of the battery 7 and the switching element 14. In addition, a shunt resistor Rv that senses a current flowing through the switching element 18 is connected in series with the switching element 18 between the low potential side of the battery 7 and the switching element 18. Further, a shunt resistor Rw that senses a current flowing through the switching element 22 is connected in series with the switching element 22 between the low potential side of the battery 7 and the switching element 22.

  On the other hand, the microcomputer (microcomputer 50) takes in the output of the position sensor 42 and the shunt resistors Ru, Rv, Rw (voltage drop amounts due to the shunt resistors Ru, Rv, Rw). The microcomputer 50 operates the switching elements 12 to 22 via the gate drive circuits 60 to 70 based on the rotation angle of the output shaft of the electric motor 4 and the currents flowing through the three phases.

  FIG. 2 shows a block diagram of processing performed by the microcomputer 50. In the present embodiment, basically, the load torque of the electric motor 4 is controlled to the required torque by triangular wave pulse width modulation (PWM) control.

  The current acquisition unit 80 takes in the outputs (voltage drop amounts ru, rv, rw) of the shunt resistors Ru, Rv, Rw, and calculates the actual currents iu, iv, iw flowing through the phases of the motor 4 based on the outputs. is there. The two-phase conversion unit 82 is a part that generates the actual current id and the actual current iq by converting the coordinates of the actual currents iu, iv, and iw into the dq axis. Incidentally, since the rotation angle of the electric motor 4 is used for this coordinate conversion, the rotation angle θ detected by the position sensor 42 is input to the two-phase conversion unit 82.

  On the other hand, the command current generator 84 is a part that generates the command currents iqc and idc according to the required torque, the rotational speed Nm as the time differential value of the rotation angle θ, and the like. These command currents iqc and idc are command values on the dq axis.

  The command voltage generator 86 calculates the d-axis command voltage vdc based on the difference between the command current idc and the actual current id, and based on the difference between the command current iqc and the actual current iq, the q-axis command voltage vqc. Is a part to calculate.

  The three-phase conversion unit 88 converts the d-axis command voltage vdc and the q-axis command voltage vqc, the U-phase command voltage basic value vub, the V-phase command voltage basic value vvb, and the W-phase command voltage basic value. This is the part that converts to vwb. These command voltage basic values vub, vvb, vwb are voltages to be applied to each phase when a command current is passed through each phase of the electric motor 4. These command voltage basic values vub, vvb, vwb are sine waves and the centers of the voltages are zero. Incidentally, since the rotation angle of the electric motor 4 is used for this coordinate conversion, the rotation angle θ detected by the position sensor 42 is input to the three-phase conversion unit 88.

  The three-phase modulation unit 90 is a part that modulates the command voltage basic values vub, vvb, and vwb to ensure that the command voltage basic values vub, vvb, and vwb are actually applied to each phase of the electric motor 4. Specifically, as shown in FIG. 3, the command voltages vucb, vvcb, and vwcb are calculated by multiplying the command voltage basic values vub, vvb, and vwb by “2 / √3”, respectively.

  The modulation method changing unit 92 corrects the command voltages vucb, vvcb, and vwcb on the basis of the rotation angle θ for the reason described later to obtain a final command voltage vuc. vvc. vwc is calculated. These final command voltages vuc, vvc, vwc are applied to the non-inverting input terminals of the comparators 96, 98, 100, respectively. Comparators 96, 98, 100 compare the command voltages vuc, vvc, vwc with the triangular carrier wave generated by the triangular wave generator 102. The output signals gu, gv, and gw of the comparators 96, 98, and 100 are obtained by pulse width modulation (PWM) of the command voltages vuc, vvc, and vwc, respectively. That is, the final command voltages vuc, vvc, vwc are signal waves to be compared with carriers in PWM control.

  The output signals gu, gv, gw and their inverted signals by the inverters 104, 106, 108 are taken into the Deadtime generator 110. The Deadtime generating unit 110 shapes the waveform of each of the output signals and the inverted signal corresponding to the signals so as to avoid the overlapping of the timings of the edge portions. The waveform-shaped signal includes an operation signal gup for operating the U-phase switching element 12, an operation signal gun for operating the U-phase switching element 14, and an operation signal gvp for operating the V-phase switching element 16, V-phase. The operation signal gvn for operating the switching element 18, the operation signal gwp for operating the W-phase switching element 20, and the operation signal gwn for operating the W-phase switching element 22.

  In this embodiment, as shown in FIG. 4, the calculation of the command voltages vuc, vvc, vwc and the acquisition of the voltage drop amounts ru, rv, rw are performed in synchronization with the carrier cycle. 4A shows the carrier according to the present embodiment, FIG. 4B shows the calculation timing (sampling timing) of the command voltages vuc, vvc, and vwc, and FIG. 4C shows the voltage drop amount. The capture timing (sampling timing) of ru, rv, and rw is shown. As shown in the drawing, the carrier according to the present embodiment is an isosceles triangular signal having the same ascending speed and descending speed. The command voltages vuc, vvc, vwc are calculated every time the carrier becomes the lower limit value. Further, each time the carrier becomes the upper limit value, the voltage drop amounts ru, rv, rw are taken. As a result, the voltage drop amounts ru, rv, rw can be amounts corresponding to the average value of the three-phase currents during the period from when the carrier reaches the lower limit value until it reaches the next lower limit value. This is due to the following reason.

  FIG. 5A shows an expanded carrier, FIG. 5B shows the transition of the output signal gu of the comparator 96, and FIG. 5C shows the transition of the output signal gv of the comparator 98. FIG. 5D shows the transition of the output signal gw of the comparator 100. As shown in the figure, the command voltages vuc, vvc, and vwc do not change over one period until the carrier becomes the next lower limit value from the lower limit value. For this reason, the magnitude relationship between the carrier and the command voltages vuc, vvc, and vwc is axisymmetric with respect to the timing at which the carrier becomes the upper limit value. Therefore, the output signals gu, gv, and gw are also line symmetric with respect to the timing when the carrier reaches the upper limit value, and the operation modes of the switching elements 12 to 22 are also line symmetric with respect to the timing when the carrier reaches the upper limit value. For this reason, the current flowing through each phase of the electric motor 4 is axisymmetric with respect to the timing at which the carrier reaches the upper limit value. Therefore, the current at each phase at the timing at which the carrier reaches the upper limit value is the current within the carrier cycle. The average value of

  The current acquisition unit 80 shown in FIG. 2 makes the calculation method of the actual currents iu, iv, iw variable according to the operation mode of the switching elements 12-22. This will be described below.

  The operation modes of the switching elements 12 to 22 are represented by eight voltage vectors shown in FIG. Here, the voltage vector V0 represents that all of the lower switching elements 14, 18, and 22 of the arms of each phase are in the ON state. Further, the odd voltage vectors V1, V3, and V5 represent that the upper switching element is in the ON state only for the one-phase arm. Further, the even voltage vectors V2, V4, and V6 represent that only the one-phase arm has the lower switching element on. The voltage vector V7 represents a state in which the upper switching elements 12, 16, and 20 of all the phase arms are in the ON state.

  Here, in the voltage vector V <b> 0, current flows through the switching elements 14, 18, and 22, so the voltage drop amounts of the shunt resistors Ru, Rv, and Rw represent currents that flow through the phases of the motor 4. In the odd voltage vectors V1, V3, and V5, since the lower switching element is in the on state in the two-phase arm, the voltage drop amount of the shunt resistors Ru, Rv, and Rw is the electric motor for these phases. 4 represents the amount of current flowing through 4. The remaining one phase can be estimated based on Kirchhoff's law. That is, for example, in the voltage vector V1, in the U-phase arm, since the lower switching element 14 is in the OFF state, the actual voltage iv, iw is calculated based on the actual currents iv, iw calculated from the voltage drop amounts of the shunt resistors Rv, Rw. The current iu can be estimated.

  In this way, the three-phase current flowing through the electric motor 4 can be acquired in the voltage vector V0 or the odd voltage vectors V1, V3, and V5. Then, in order to make the calculation method of the actual currents iu, iv, and iw variable according to the voltage vector, the modulation method changing unit 92 shown in FIG. 2 previously selects any one of the voltages based on the command voltages vucb, vvcb, and vwcb. A flag indicating whether to use the calculation method is output. That is, a three-phase detection flag that instructs to use the voltage drop amounts ru, rv, and rw of the shunt resistors Ru, Rv, and Rw for all three phases, a U-phase estimation flag that instructs to estimate one phase, and a V-phase estimation. Either Flag or W phase estimation Flag is output.

  This output is stored in the memory 112 shown in FIG. That is, the memory 112 stores the flag output from the modulation method changing unit 92 as shown in FIG. In the current acquisition unit 80 shown in FIG. 2, the calculation method is variably set based on the flag stored in the memory 112.

  FIG. 8 shows a procedure of current calculation processing by the current acquisition unit 80. This process is repeatedly executed by the microcomputer 50 at a predetermined cycle, for example.

  That is, if the three-phase detection flag is on (step S10: YES), the actual currents iu, iv, iw are calculated based on the voltage drop amounts ru, rv, rw of the shunt resistors Ru, Rv, Rw. Further, if any of the U-phase estimation flag, the V-phase estimation flag, and the W-phase estimation flag is on (YES in any of steps S14, S20, and S26), the voltage drop amount of the shunt resistor is set for the other phases. Use (steps S16, S22, S28) and estimate the corresponding phase (steps S18, S24, S30).

  By the way, with the operation of the switching elements 12 to 22, ringing noise is superimposed on the current flowing through each phase of the electric motor 4. Therefore, if the ringing noise is not sufficiently attenuated at the timing of taking in the voltage drops ru, rv, rw, the voltage drops ru, rv, rw to be taken in are average values of currents in one cycle of the carrier. The value is not appropriate. On the other hand, in a region where the modulation rate, which is a percentage of the amplitude of the command voltages vuc, vvc, vwc with respect to the carrier amplitude, is large, the command voltages vuc, vvc, vwc have more opportunities than the carrier. The period tends to be shorter.

  FIG. 9 <A> shows the transition of the command voltages vuc, vvc, vwc (in which the third harmonic is superimposed on the command voltages vucb, vvcb, vwcb) when the modulation factor is “96%”. In FIG. 9 <A>, the maximum value MAX of the command voltages vuc, vvc, vwc matches the upper limit value of the carrier, which corresponds to the voltage of the battery 7. In this case, the command voltages vuc, vvc, vwc at an electrical angle of 120 ° are as shown in FIG. 9A, and the output signals gu, gv, gw are as shown in FIGS. 9B to 9D. The voltage vector pattern at this time is as shown in FIG. Moreover, the induced voltage of each phase of the electric motor 4 at this time is as shown in FIG. Incidentally, the broken line in FIG. 9F indicates that the voltage of each phase is zero. At this time, the current flowing through each phase of the motor 4 (more precisely, the DC component excluding ringing) is as shown in FIG. In this example, since the generation period of the voltage vector V0 is short, within this period, as illustrated in FIG. 9 <B> for the W-phase actual current iw, at an intermediate point in the generation period of the voltage vector V0. The ringing noise is not attenuated enough. For this reason, the voltage drop amounts ru, rv, rw at the intermediate point in the generation period of the V0 vector, which is the timing at which the carrier reaches the upper limit value, are not appropriate values as the average value of the current in one cycle of the carrier.

  Here, a condition in which the period of the voltage vector V0 or the voltage vectors V1, V3, and V5 is sufficiently long will be considered.

  For example, in FIG. 10 <A>, when the command voltage vvc becomes the minimum value MIN, the switching element 18 in the lower stage of the V-phase arm is fixed to the ON state as shown in FIG. 10 <B> for one carrier period. Is done. For this reason, as shown in FIGS. 10A to 10G corresponding to the previous FIGS. 9A to 9G, the generation period of the voltage vector V0 is prolonged.

  Further, for example, in FIG. 11 <A>, when the command voltage vuc reaches the maximum value MAX, the switching element 12 in the upper stage of the U-phase arm is in the ON state as shown in FIG. 11 <B> for one carrier period. Fixed to. For this reason, as shown in FIGS. 11A to 11G corresponding to FIGS. 9A to 9G, the generation period of the voltage vector V1 is prolonged, and the voltage vector V1 The generation period includes the timing when the carrier becomes the upper limit value.

  In view of the above, in the present embodiment, the three-phase modulation unit 90 in FIG. 2 is expanded in order to expand the generation period of the voltage vector V0 or the generation period of the odd voltage vectors V1, V3, V5 at the timing of the carrier upper limit value. The command voltages vucb, vvcb, and vwcb output from are corrected.

  Specifically, in order to extend the generation period of the voltage vector V0, any one of the switching elements 14, 18, and 22 at the lower stage of the arm is used as a carrier while maintaining the relative magnitude relationship of the command voltages vucb, vvcb, and vwcb. The command voltages vucb, vvcb, and vwcb are corrected so as to be fixed to the ON state over one cycle of As a result, the interphase voltages determined by the final command voltages vuc, vvc, and vwc are equal to the interphase voltages determined by the command voltages vucb, vvcb, and vwcb. Therefore, the current flowing through the motor 4 is highly accurate to the command currents idc and iqc. Can be approximated. In addition, the generation period of the voltage vector V0 can be extended by fixing any one of the switching elements 14, 18, and 22 in the lower stage of the arm.

  Further, when the generation period of the voltage vector V0 cannot be sufficiently expanded by the above processing, the odd voltage vectors V1, V3, and V5 are expanded. That is, the command to fix one of the switching elements 12, 16, and 20 on the upper stage of the arm to the ON state over one cycle of the carrier while maintaining the relative magnitude relationship of the command voltages vucb, vvcb, and vwcb. The voltages vucb, vvcb, and vwcb are corrected. As a result, the interphase voltages determined by the final command voltages vuc, vvc, and vwc are equal to the interphase voltages determined by the command voltages vucb, vvcb, and vwcb. Therefore, the current flowing through the motor 4 is highly accurate to the command currents idc and iqc. Can be approximated. Moreover, the generation period of the voltage vectors V1, V3, and V5 can be expanded by fixing any one of the upper switching elements 12, 16, and 20 of the arm.

  FIG. 12 shows a processing procedure of the modulation method changing unit 92. This process is repeatedly executed by the microcomputer 50 in synchronization with the carrier cycle.

  In this series of processing, first, in step S30, based on the command voltages vucb, vvcb, and vwcb, the generation period of the zero voltage vector composed of the voltage vector V0 and the voltage vector V7 and the odd voltage vector V1 within one cycle of the carrier. , V3, V5 generation period. Here, the generation period of the odd voltage vectors V1, V3, V5 is calculated as a period in which any one of them is larger than the carrier based on the values of the command voltages vucb, vvcb, vwcb.

  In addition, the generation period of the zero voltage vector is based on the values of the command voltages vucb, vvcb, and vwcb, and is a period in which all of these are larger than the carrier and a period in which all of them are smaller than the carrier. Calculated as the sum. Here, the zero voltage vector generation period is a generation period of the voltage vector V0 realized by fixing any of the switching elements 14, 18, and 22 in the lower stage of the arm to the ON state. That is, for example, by fixing the W-phase command voltage vwc to the minimum value MIN in FIG. 9, the voltage vector V0 generation period shown in FIG. 9E is expanded and the generation period of the voltage vector V7 disappears. . The amount of expansion of the voltage vector V0 is the disappearance period of the voltage vector V7.

  In subsequent step S32, it is determined whether or not the zero voltage vector generation period is equal to or longer than the odd voltage generation period. This process determines whether or not to extend the generation period of the voltage vector V0. Here, in the odd voltage vector generation period, it is determined whether or not the generation period of the voltage vector V0 is sufficiently long by fixing any one of the switching elements 14, 18, and 22 to the on state. It is a threshold value. That is, even if the generation period of the voltage vector V0 is expanded, if it is shorter than the generation period of the odd voltage vectors V1, V3, V5, the voltage drop amounts ru, rv, rw are taken in the odd voltage vectors V1, V3, V5. However, it can be determined that the influence of ringing noise is small.

  When it is determined that the period is equal to or longer than the odd voltage generation period, the process proceeds to step S34 in order to extend the generation period of the voltage vector V0. In step S34, the 3 detection flag is turned on. This is because when any one of the switching elements 14, 18, and 22 at the lower stage of the arm is fixed to be in an ON state in order to extend the generation period of the voltage vector V0, the timing at which the carrier becomes the upper limit value is This is because it is included in the generation period.

  In the subsequent step S36, processing for correcting the command voltages vucb, vvcb, vwcb is performed. Here, among the command voltages vucb, vvcb, and vwcb, the minimum phase is fixed at the minimum value MIN. Then, the remaining two are corrected for decrease by a voltage correction amount Δ by setting the minimum phase to the minimum value MIN. Thereby, the interphase voltage determined by the command voltages vuc, vvc, and vwc can be made equal to the interphase voltage determined by the command voltages vucb, vvcb, and vwcb, and any one phase of the lower switching elements 14, 18, and 22 can be set. Can be fixed in the on state.

  On the other hand, when it is determined in step S32 that the period is less than the odd voltage vector generation period, the process proceeds to step S38 in order to extend the generation period of the odd voltage vectors V1, V3, and V5. Here, the generation period of the odd-numbered voltage vectors V1, V3, V5 is expanded because if the command voltages vucb, vvcb, vwcb are used as they are, the timing at which the carrier becomes the upper limit value may be included in the voltage vector V0. Because there is. In step S38, the three-phase detection flag is turned off. This is because when any one of the upper switching elements 12, 16, and 20 is fixed in an ON state so as to expand the odd voltage vectors V1, V3, and V5, the timing at which the carrier becomes the upper limit value is the odd voltage vector V1. , V3 and V5 are included in the generation period.

  In the subsequent step S40, processing for correcting the command voltages vucb, vvcb, vwcb is performed. Here, among these command voltages vucb, vvcb, and vwcb, the maximum phase is fixed at the maximum value MAX. Then, the remaining two are increased and corrected by a voltage correction amount Δ by setting the maximum phase to the maximum value MAX. As a result, the interphase voltage determined by the command voltages vuc, vvc, and vwc can be made equal to the interphase voltage determined by the command voltages vucb, vvcb, and vwcb, and any one of the switching elements 12, 16, and 20 in the upper stage can be set. Can be fixed in the on state.

  In subsequent steps S42 to S58, processing for turning on any of the U-phase estimation flag, the V-phase estimation flag, and the W-phase estimation flag is performed in order to give an instruction to estimate the current of the phase fixed in the on state. Do.

  According to the above processing, the period in which the timing at which the carrier reaches the upper limit value is included in the odd voltage vectors V1, V3, V5 or the voltage vector V0 and includes the timing at which the upper limit value is reached can be extended.

  FIG. 13 shows the relationship between the minimum value (minimum pulse width) of the generation period of the voltage vector V0 and the modulation rate (modulation rates of the command voltages vucb, vvcb, and vwcb) by the above processing. As shown in the figure, by correcting the command voltages vucb, vvcb, and vwcb, the minimum pulse width can be expanded as compared with the case where there is no correction shown as a conventional method by a one-dot chain line in the figure.

  FIG. 14 (a1) shows the transition of the command voltages vuc, vvc, vwc of this embodiment when the modulation rate of the command voltages vucb, vvcb, vwcb is 96%, and FIG. 14 (b1) shows the transition at that time. The generation periods of the voltage vector V0 and the odd voltage vector are shown. As shown in the figure, in this case, when the voltage vector V0 is generated (when it is not zero), the minimum value of the generation period can be set to about 6 μsec. On the other hand, FIG. 14A2 shows a case where the command voltages vucb, vvcb, and vwcb are not corrected (more precisely, the third harmonic is superimposed on the command voltages vucb, vvcb, and vwcb). In this case, as shown in FIG. 14 (b2), the minimum value of the generation period when the voltage vector V0 is generated is about 1 μsec. As long as the voltage vector V0 is generated, the timing at which the carrier reaches the upper limit value is included by the voltage vector V0. For this reason, when the voltage drop amounts ru, rv, rw are taken in, the influence of ringing is greatly affected.

  In FIG. 15, the command voltages vucb, vvcb, and vwcb are corrected so that any of the switching elements 12 to 22 is fixed at every electrical angle of 60 ° while maintaining the relative magnitude relationship between the command voltages vucb, vvcb, and vwcb. The conventional two-phase modulation method is compared with this embodiment. Note that FIG. 15A1 and FIG. 15B1 are the same as FIG. 14A1 and FIG. 14B1. As shown in FIG. 15 (b2), in the case of performing two-phase modulation every 60 °, when the voltage vector V0 is generated, the minimum interval is about 3 μsec. The occurrence period cannot be extended.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The voltage vector V0 generation period or the odd voltage vector generation period is expanded by fixing any one of the switching elements 12 to 22 over one cycle of the carrier, and the shunt resistor Ru is expanded in the expanded period. , Rv, Rw, voltage drop amounts ru, rv, rw were captured. As a result, the voltage drop amounts ru, rv, and rw can be captured at the timing when the ringing is sufficiently attenuated.

  (2) Voltage drops ru, rv, and rw were captured each time the carrier was a triangular wave having the same ascending speed and descending speed and the carrier reached the upper limit. Thereby, the information about the average value of the current within the carrier cycle can be easily obtained.

  (3) The command voltages vuc, vvc, vwc are updated each time the carrier becomes the lower limit value. As a result, the voltage drop amounts ru, rv, rw at the timing when the carrier reaches the upper limit value can be set to a value corresponding to the average value of the three-phase currents within the carrier cycle with high accuracy.

  (4) When any one of the switching elements 14, 18, and 22 is fixed in the on state, and the generation period of the voltage vector V0 is equal to or greater than the threshold value, any one of the above is fixed in the on state. Thereby, it is possible to quantify whether or not the voltage drop amounts ru, rv, rw can be taken in at the timing when the ringing caused by the generation of the voltage vector V0 is suppressed by the threshold value.

  (5) When the generation period of the zero voltage vector is equal to or greater than the threshold value, any one of the switching elements 14, 18, and 22 is fixed to the on state. Thereby, the threshold value can be compared with a period during which all of the switching elements 14, 18, and 22 are turned on within one carrier period.

  (6) The threshold value is an odd voltage generation period determined by comparison of the command voltages vucb, vvcb, and vwcb with the carrier. As a result, the voltage drop amounts ru, rv, and rw can be taken in with priority given to the period in which the three phases are turned on while suppressing the influence of ringing as much as possible. For this reason, it is possible to avoid the process of estimating the current of one phase from the currents of the other two phases as much as possible, and as a result, it is possible to suppress the estimation error caused by the minimum unit (LSB) of calculation.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, the threshold value used for determining whether or not to expand the voltage vector V0 generation period is settling time shown in FIG. FIG. 16A shows the generation period of the voltage vector V0, and FIG. 16B shows how ringing of the current (voltage drop amounts ru, rv, rw) flowing through the electric motor 4 occurs. In FIG. 16B, the value when there is no ringing for the current flowing through the electric motor 4 is shown as 1. The settling time is defined as the time during which the fluctuation range of the current due to ringing is within ± 5%.

  By setting the threshold value as the settling time, when the voltage drop amounts ru, rv, rw are captured within the generation period of the voltage vector V0, after the voltage vector V0 is generated, at least “½” of the settling time has elapsed. The voltage drop amounts ru, rv, rw are taken in. For this reason, the influence of ringing can be suppressed suitably.

  FIG. 17A1 shows the transition of the command voltages vuc, vvc, and vwc according to the present embodiment, and FIG. 17B1 shows the generation periods of the voltage vector V0 and the odd voltage vector. Note that FIG. 17 (a2) and FIG. 17 (b2) are the same as FIG. 15 (a2) and FIG. 15 (b2), and are shown for comparison. As shown in the figure, when the voltage vector V0 is generated also in this embodiment, the minimum period indicated by a two-dot chain line in the figure is compared with the examples shown in FIGS. 17 (a2) and 17 (b2). Can be enlarged.

  According to this embodiment described above, in addition to the effects (1) to (5) of the first embodiment, the following effects can be obtained.

  (7) The threshold is set to the settling time for the ringing of the current that occurs with the generation of the voltage vector V0. As a result, the influence of ringing can be suppressed as much as possible when the voltage drop amounts ru, rv, rw are taken in the generation period of the voltage vector V0.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  When the command voltages vucb, vvcb, and vwcb are corrected in the above-described manner, the number of times of switching within one cycle of the carrier is reduced as compared with the case where the command voltages vucb, vvcb, and vwcb are not corrected. For this reason, when the command voltages vucb, vvcb, and vwcb are corrected, the amount of fluctuation of the current flowing through the motor 4 becomes larger than when the command voltages are not corrected. When the current fluctuation amount increases, the output torque fluctuation amount of the electric motor 4 also increases. For this reason, it is desirable not to perform the correction of the command voltages vucb, vvcb, and vwcb from the viewpoint of suppressing fluctuations in output torque.

  Therefore, in the present embodiment, it is determined whether or not to perform correction based on the command voltages vucb, vvcb, and vwcb having the largest value. This is because the generation period of the voltage vector V0 is determined by the one having the largest value as shown in FIG. For this reason, in the present embodiment, the correction is performed when the largest value of the command voltages vucb, vvcb, and vwcb is equal to or greater than the threshold value β. Here, when the timing at which the carrier reaches the upper limit value is included in the voltage vector V0 generation period, the threshold value β sufficiently suppresses the influence of ringing associated with the generation of the voltage vector V0 at the timing at which the carrier reaches the upper limit value. It is set to a value that is assumed to be possible.

  FIG. 19 is a block diagram showing processing performed by the microcomputer 50 according to the present embodiment. In FIG. 19, the same reference numerals are assigned to the blocks corresponding to the blocks shown in FIG.

  As illustrated, the present embodiment includes a modulation method switching determination unit 120. FIG. 20 shows a procedure of processing performed by the modulation method switching determination unit 120. This process is repeatedly executed by the microcomputer 50 at the same cycle as the carrier cycle.

  In this series of processing, in step S60, it is determined whether or not the largest one of the command voltages vucb, vvcb, and vwcb is greater than or equal to the threshold value β. When it is determined that the value is equal to or greater than the threshold value β, the correction flag is turned on in step S62 to indicate that the command voltages vucb, vvcb, and vwcb are to be corrected. On the other hand, if it is less than the threshold value β, the correction flag is turned off in step S64 to give an instruction not to correct the command voltages vucb, vvcb, and vwcb.

  FIG. 21 shows a procedure of processing performed by the modulation method changing unit 92 in the present embodiment. This process is repeatedly executed by the microcomputer 50 at the same cycle as the carrier cycle. In FIG. 21, the same steps as those shown in FIG. 12 are given the same step numbers for the sake of convenience.

  In this series of processing, it is determined in step S70 whether or not the correction flag is off. If the correction flag is off, the 3 detection flag is turned on in step S72. Subsequently, in step S74, the third-order harmonic is superimposed on the command voltages vucb, vvcb, and vwcb, and this series of processes is temporarily terminated. On the other hand, if it is determined that the correction flag is not OFF, the processes of steps S30 to S58 in FIG. 12 are performed.

  According to this embodiment described above, the following effects can be obtained in addition to the effects (1) to (6) of the first embodiment.

  (8) Based on the largest value among the command voltages vucb, vvcb, and vwcb, it was determined whether or not to correct the command voltages vucb, vvcb, and vwcb. Thereby, the fluctuation amount of the current flowing through the three phases can be suppressed as much as possible while suppressing the influence of ringing when the voltage drop amounts ru, rv, rw are taken.

(Fourth embodiment)
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the third embodiment.

  In the present embodiment, the threshold value β is set as a ringing settling time accompanying the generation of the voltage vector V0. 22 (a) and 22 (b) are the same as FIGS. 16 (a) and 16 (b). Thereby, also by this embodiment, when the voltage vector V0 generate | occur | produces, the fluctuation amount of the electric current which flows through 3 phases can be suppressed as much as possible, ensuring the generation | occurrence | production period enough.

(Fifth embodiment)
Hereinafter, the fifth embodiment will be described with reference to the drawings with a focus on differences from the third embodiment.

  FIG. 23 shows the overall configuration of the electric motor 4 and its control system according to the present embodiment. In FIG. 23, members corresponding to those shown in FIG. 1 are given the same reference numerals for convenience.

  As shown in the figure, in this embodiment, shunt resistors Ru, Rv, and Rw that detect currents flowing through the switching elements 12, 16, and 20 are provided in series with the switching elements 12, 16, and 20, respectively. That is, a shunt resistor Ru that senses a current flowing through the switching element 12 is connected in series between the battery 7 and the switching element 12. In addition, a shunt resistor Rv that senses a current flowing through the switching element 16 is connected in series between the battery 7 and the switching element 16. Further, a shunt resistor Rw that senses a current flowing through the switching element 20 is connected in series between the battery 7 and the switching element 20. In this case, in the generation period of the voltage vector V7 or the even voltage vectors V2, V4, V6, the current flowing through the motor 4 can be calculated based on the voltage drop amounts ru, rv, rw.

  Therefore, in the present embodiment, as shown in FIG. 24, the sampling timing of the command voltages vuc, vvc, vwc is set as the timing at which the carrier reaches the upper limit value, and the sampling timing of the voltage drop amounts ru, rv, rw is set at the carrier. The timing is the lower limit. Further, as shown in FIG. 25, when the smallest one of the command voltages vucb, vvcb, and vwcb is equal to or less than the threshold value β, the command is generated to extend the generation period of the voltage vector V7 or the even voltage vectors V2, V4, and V6. The voltages vucb, vvcb, and vwcb are corrected. This is because in the present embodiment, the generation period of the voltage vector V7 is determined by the value of the smallest one of the command voltages vucb, vvcb, and vwcbb. In consideration of the fact that the generation period of the voltage vector V7 becomes shorter as the value of the smallest one of the command voltages vucb, vvcb, and vwcb is smaller, the threshold β is smaller than that shown in FIG. Is set to

  FIG. 26 shows a processing procedure of the modulation method switching determination unit 120 in the present embodiment. In FIG. 26, the same processing as the processing shown in FIG. 20 is given the same step number for convenience. In the present embodiment, in step S60a, it is determined whether or not the smallest value of the command voltages vucb, vvcb, and vwcb is equal to or less than the threshold value β. When it is equal to or less than the threshold value β, the process proceeds to step S62, and when it is greater than the threshold value β, the process proceeds to step S64.

  FIG. 27 shows a processing procedure of the modulation method changing unit 92 in the present embodiment. In FIG. 27, the same processing as the processing shown in FIG. 21 is given the same step number for convenience.

  In this series of processing, in step S30a, based on the command voltages vucb, vvcb, and vwcb, the generation period of the zero voltage vector and the generation periods of the even voltage vectors V2, V4, and V6 are calculated. The generation period of the even voltage vector may be calculated as a period in which two of the command voltages vucb, vvcb, and vwcb are larger than the carrier in one cycle of the carrier. In step S32a, it is determined whether the generation period of the zero voltage vector is equal to or longer than the generation period of the even voltage vector.

  If it is determined that the generation period of the even voltage vector is longer than the generation period, the process proceeds to step S36a through step S34. In step S36a, the maximum command voltage vucb, vvcb, vwcb is fixed to the maximum value MAX of the command voltage. Then, the value obtained by subtracting the maximum value from the maximum value MAX is set as a correction amount Δ, and the other two-phase command voltages are increased and corrected. On the other hand, when it is determined that it is shorter than the generation period of the even voltage vector, the process proceeds to step S40a through step S38. In step S40a, the smallest value among the command voltages vucb, vvcb, vwcb is fixed to the minimum value MIN of the command voltage. Then, the amount obtained by subtracting the minimum value MIN from the smallest value is used as the correction amount Δ, and the other two-phase command voltages are corrected to decrease by the correction amount Δ.

  According to the present embodiment described above, the same effect as in the third embodiment can be obtained.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In the second embodiment, the threshold value α may be twice the settling time. As a result, when the voltage drop amounts ru, rv, rw are captured during the generation period of the voltage vector V0, the settling time has already elapsed since the generation of the voltage vector V0. For this reason, the influence of ringing noise on the voltage drop amounts ru, rv, rw can be less than 5%. The setting of the threshold value α is not limited to this, and may be changed as appropriate.

  In the configuration shown in FIG. 1, the generation period of the voltage vector V0 tends to be shorter as the modulation rate is higher. In the configuration shown in FIG. 23, the generation period of the voltage vector V7 is higher as the modulation rate is higher. In view of the fact that the voltage tends to be short, it may be determined whether to correct the command voltages vucb, vvcb, and vwcb according to the modulation rate.

  The threshold value β setting method according to the third to fifth embodiments is not limited to those exemplified in these embodiments. For example, the threshold β in the fifth embodiment may be set such that the generation period of the voltage vector V7 is the settling time of the ringing of the current accompanying the generation of the voltage vector V7, as in the fourth embodiment. . The threshold β sufficiently suppresses the influence of ringing without correcting the command voltages vucb, vvcb, and vwcb when the voltage drops ru, rv, and rw are taken in the generation period of the voltage vector V0 and the voltage vector V7. What is necessary is just to set to the value which can judge whether it will be what was done.

  In the configuration shown in FIG. 23, the first embodiment may be applied. This can be realized by the processing of steps S30a to S58 in FIG.

  In the configuration shown in FIG. 23, the first embodiment may be applied. This is because the processing of steps S30a to S58 in FIG. 27 is performed and, instead of step S32a, the threshold value α to be compared with the zero voltage vector generation period is set as the ringing time of the current ringing accompanying the generation of the voltage vector V7. And it is sufficient. If the threshold value α is set to, for example, twice the settling time, the settling time has already elapsed from the generation of the voltage vector V7 when the voltage drop amounts ru, rv, rw are taken in the generation period of the voltage vector V7. It will be. For this reason, the influence of ringing on the voltage drops ru, rv, rw can be reduced to 5% or less.

  In each of the above embodiments, the zero voltage vector generation period is compared with the threshold value α (or even voltage vector generation period, odd voltage vector generation period), but the present invention is not limited to this. For example, in the first to fourth embodiments, the generation period of the voltage vector V0 and the threshold value α may be compared. For example, in the fifth embodiment, the generation period of the voltage vector V7 may be compared with the threshold value α.

  In each of the above embodiments, the switching elements 14, 18, and 22 in the lower arm are turned on when the carrier is larger than the command voltage. However, the present invention is not limited to this, and the lower arm in the lower arm when the carrier is smaller than the command voltage. The switching elements 14, 18, and 22 may be turned on. In this case, in the first to fourth embodiments, it is desirable that the command voltage is calculated every time the carrier becomes the upper limit value, and the voltage drop amount is taken in every time the carrier becomes the lower limit value. In the fifth embodiment, it is desirable to take in the voltage drop every time the carrier reaches the upper limit and calculate the command voltage every time the carrier reaches the lower limit.

  Even if the command voltage calculation timing is not the same as that in each of the above embodiments and the modifications thereof, the same effect as in each of the above embodiments can be obtained as long as the change in the command voltage within one carrier cycle is small. That is, for example, in FIG. 5, even if the command voltage is calculated every time the carrier reaches the upper limit value, if the change is small, the output signals gu, gv, and gw are substantially the same as the timing at which the carrier reaches the upper limit value. Since it becomes line symmetrical, the current flowing through the electric motor 4 at the timing when the carrier becomes the upper limit value can be set to about the average value within one cycle of the carrier.

  The carrier is not limited to an isosceles triangle shape in which the rising speed and the falling speed are the same. For example, a sawtooth shape may be used. Even in this case, expanding the generation period of the voltage vector V0 and the voltage vector V7 is effective in suppressing the influence of ringing when the voltage drop amount is taken in the generation period of the voltage vector V0 and the voltage vector V7. It is.

  The control device for the electric motor 4 is not limited to one that performs dq conversion. Further, the processes exemplified in the above embodiments are not limited to those realized by software processing of the microcomputer 50, and may be realized by dedicated hardware means.

  The sensing means for sensing the current flowing through the upper and lower switching elements of the inverter 10 is not limited to the shunt resistors Ru, Rv, Rw, and may be a current sensor, for example.

  -In this embodiment, although the electric motor 4 was applied as a rotary machine, not only this but a generator may be sufficient. Further, the present invention may be applied not only to a control device for a rotating machine mounted on a hybrid vehicle but also to a control device for a rotating machine mounted on an electric vehicle.

The figure which shows the structure of the electric motor concerning 1st Embodiment, and its control system. The functional block diagram which shows the process in the microcomputer concerning the embodiment. The flowchart which shows the process of the three-phase modulation part concerning the embodiment. The figure which shows the relationship between the carrier concerning each embodiment, and each sampling timing of command voltage and voltage drop amount. The time chart which shows the relationship between the carrier concerning the same embodiment, and the switching mode of each switching element of an inverter. The figure which shows a voltage vector. The flowchart which shows the process of the memory concerning the said embodiment. The flowchart which shows the process sequence of the electric current acquisition part concerning the embodiment. The figure which shows the problem of the electric current detection based on shunt resistance. The figure which shows the point of interest of the said embodiment. The figure which shows the point of interest of the embodiment. The flowchart which shows the process sequence of the modulation method modulation | alteration part of the embodiment. The figure which shows the generation | occurrence | production period of the voltage vector V0 by the embodiment. The figure which shows the generation | occurrence | production period of the voltage vector V0 by the embodiment. The figure which shows the generation | occurrence | production period of the voltage vector V0 by the embodiment. The figure which shows the setting aspect of the expansion determination threshold value of the generation | occurrence | production period of the voltage vector V0 concerning 2nd Embodiment. The figure which shows the generation | occurrence | production period of the voltage vector V0 concerning the embodiment. The figure which shows threshold value (beta) which judges the presence or absence of execution of the correction | amendment of the command voltage concerning 3rd Embodiment. The functional block diagram which shows the process in the microcomputer concerning 3rd Embodiment. 7 is a flowchart showing a processing procedure of a modulation method switching determination unit according to the embodiment. The flowchart which shows the process sequence of the modulation method change part of the embodiment. The figure which shows the setting aspect of threshold value (beta) which judges the presence or absence of execution of the correction | amendment of the command voltage concerning 4th Embodiment. The figure which shows the structure of the electric motor concerning 5th Embodiment, and its control system. The figure which shows the relationship between the carrier concerning each embodiment, and each sampling timing of command voltage and voltage drop amount. The figure which shows the setting aspect of threshold value (beta) which judges the presence or absence of execution of the correction | amendment of the command voltage concerning the embodiment. 7 is a flowchart showing a processing procedure of a modulation method switching determination unit according to the embodiment. The flowchart which shows the process sequence of the modulation method change part of the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 4 ... Electric motor (one embodiment of a three-phase rotating machine), 10 ... Inverter, 50 ... Microcomputer (one embodiment of a control apparatus of a three-phase rotating machine), 80 ... Current acquisition part (one embodiment of an acquisition means), 92 ... Modulation method changing section (one embodiment of fixing means).

Claims (9)

In order to control the output of the three-phase rotating machine, the output of the sensing means for sensing the current flowing through the upper and lower switching elements of the inverter arm is taken in, and the output of the three-phase rotating machine is controlled as desired. In a control device for a three-phase rotating machine that operates the inverter by pulse width modulation based on a comparison between a three-phase signal wave and a carrier wave,
The signal to be compared with the carrier wave in order to selectively expand either the period in which the two-phase on the sensing means side of the switching element of the inverter is on or the period in which the three-phase is on. Fixed to fix the on-state one-phase switching element of the upper or lower stage of the inverter arm while maintaining the relative magnitude relationship between the signal waves over one period of the carrier by correcting the wave Means,
3. A control device for a three-phase rotating machine, comprising: an acquisition unit that acquires an electric current flowing through the three-phase rotating machine by capturing an output of the sensing unit within the selectively expanded period. The carrier wave is a triangular wave having substantially the same rising speed and falling speed,
2. The control device for a three-phase rotating machine according to claim 1, wherein the acquisition unit captures the output of the sensing unit each time the carrier wave is in the vicinity of the upper limit value or the lower limit value. The signal wave is updated each time the carrier wave is near the upper limit value or the lower limit value,
3. The control device for a three-phase rotating machine according to claim 2, wherein the acquisition unit captures the output of the sensing unit in the vicinity of an intermediate point in the update period of the signal wave.   The fixing means fixes the one-phase switching element on the sensing means side in the ON state, and when the period during which the switching elements on the sensing means side is in the ON state is equal to or greater than a threshold value, The control device for a three-phase rotating machine according to any one of claims 1 to 3, wherein the one-phase switching element is fixed in an on state.   In the fixing means, the sum in one period of the carrier wave for the period in which the three phases on the sensing means side determined by the comparison between the signal wave to be corrected and the carrier wave are in the on state and in the off state is a threshold value. When the above is true, the one-phase switching element on the sensing means side is fixed in the ON state, and when the sum is less than the threshold value, the one-phase switching element on the non-sensing means side is fixed in the ON state. The three-phase rotating machine control device according to claim 4.   6. The three-phase rotating machine according to claim 4, wherein the threshold value is a period in which two phases on the sensing means side determined by a comparison between a signal wave to be corrected and the carrier wave are in an on state. Control device.   5. The threshold value is set to be equal to or longer than a settling time for ringing of a current flowing through the three phases generated when the three-phase switching element on the sensing means side is turned on. 5. A control device for a three-phase rotating machine according to 5. Based on the value of the signal wave having the shortest period during which the switching element on the sensing means side is turned on among the three-phase signal waves to be corrected by the fixing means, the signal waves are corrected by the fixing means. A judgment means for judging whether or not to perform,
When the correction is not performed, the acquisition means outputs the output of the sensing means during either the period when the two phases on the sensing means side of the switching elements of the inverter are in the on state or the period when the three phases are in the on state. The control device for a three-phase rotating machine according to any one of claims 1 to 7, wherein   The determination means includes a current flowing in the three phases that is generated when the switching element on the sensing means side is turned on during a period in which the switching element on the sensing means side in the shortest phase is turned on. 9. The control device for a three-phase rotating machine according to claim 8, wherein when it is equal to or less than a settling time for the ringing, it is determined that the correction is performed.

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