JP4715715B2 - Control device for three-phase rotating machine - Google Patents

Description

  The present invention relates to a control device for a three-phase rotating machine that controls the output of a three-phase motor by operating a switching element of an inverter.

  About an inverter provided with a switching element (IGBT) that conducts each of the three phases of a three-phase motor and either the positive electrode side or the negative electrode side of the power supply voltage and a flywheel diode (FWD) connected in reverse parallel thereto A control device for controlling the output torque of the electric motor by operating is well known. Also, at this time, there are those that operate the inverter based on duty control according to the command voltage so that the actual voltage applied to each phase of the three-phase motor becomes the command voltage having periodicity. It is well known. However, in such a control device, when the frequency of the command voltage is low, the average current of one IGBT of a specific arm is larger than the effective value when the maximum current flows through the IGBT at a high frequency. This may increase power loss due to the IGBT. An increase in power loss leads to an increase in the amount of heat generated, and as a result, a demand for a large-sized device such as an IGBT is generated.

Therefore, conventionally, as seen in Patent Document 1, for example, when the frequency of the command voltage is low, it has been proposed to correct the command voltages of the three phases with a predetermined offset voltage. Thereby, the power loss by IGBT with the largest power loss can be reduced.
JP 2002-272125 A

  By the way, when reducing the power loss of the IGBT by correcting the command voltage by the offset voltage, the power loss of the FWD connected in antiparallel with the IGBT increases. Furthermore, the total power loss in the inverter may increase due to the correction of the command voltage by the offset voltage.

  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 capable of operating an inverter more appropriately under a situation where the rotational speed of the three-phase rotating machine is low. There is.

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

In the invention according to claim 1, when the three-phase modulation processing means for operating each of the three-phase switching elements by the duty control and the command voltage for each phase having a maximum absolute value are positive, When the command voltage of each phase is corrected by an amount necessary to set the command voltage as the voltage of the positive electrode input terminal of the inverter, and the voltage having the maximum absolute value is negative, the command voltage is converted to the inverter When the rotation speed of the three-phase rotating machine is equal to or lower than a predetermined speed, two-phase modulation processing means for correcting the command voltage of each phase by an amount necessary for setting the voltage of the negative input terminal of In this case, a switching means that uses both of these processes by switching between the processing by the three-phase modulation processing means and the processing by the two-phase modulation processing means is provided. When the processing by the three-phase modulation processing unit Te is made, from that the command voltage according to the two-phase modulation processing means and correcting at opposite sign of the offset voltage.

  The two-phase modulation process usually has a smaller total power loss of the inverter than the three-phase modulation process. However, according to the two-phase modulation process, the power loss of the switching element fixed in the ON state tends to be larger than that in the three-phase modulation process. In this regard, in the above configuration, the inverter can be operated more appropriately by using these two processes in combination when the rotation speed of the three-phase rotating machine is equal to or lower than a predetermined speed. That is, for example, the total power loss of the inverter can be reduced as compared with the case of only the three-phase modulation processing. In addition, for example, when the switching element is an element that restricts the flow direction of current between the input terminal and the output terminal in one direction, and the rectifier is connected in reverse parallel to the switching element, only by the two-phase modulation processing As a result, the power loss of the rectifying means can be reduced.

According to a third aspect of the present invention, in the first or second aspect of the invention, the switching element is an element that regulates a current flow direction between the input terminal and the output terminal in one direction, and the inverter is the switching element. further characterized in that to obtain Bei rectifying means connected to the elements and reverse parallel.

In the above configuration, when the correction is performed as compared with the case where the command voltage is not corrected by the offset voltage, the phase is the phase where the absolute value is maximized and the element is different from the switching element where the power loss is maximized. The power loss of the rectifying means connected in antiparallel increases. In this regard, in the above configuration, by using the two-phase modulation process in combination, it is possible to reduce the power loss of the specific switching element and to suppress an increase in the power loss of the rectifying means.

  The “switching element that maximizes the power loss” is a switching element that maximizes the power loss determined by the command voltage before correction.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the switching means includes an element temperature of the inverter, the duty, the command voltage, and a rotation angle of the three-phase rotating machine. The processing time of the processing by the three-phase modulation processing means and the processing by the two-phase modulation processing means is variably set according to at least one of the actual current flowing through the three-phase rotating machine and the offset voltage. Features.

  The power loss of each switching element and the rectifying means due to the offset process and the two-phase modulation process varies depending on the element temperature, duty, command voltage, rotation angle, and offset voltage of the inverter. Further, since heat is generated due to the power loss, the power loss has a correlation with the element temperature. In the above configuration, the inverter is configured by variably setting each processing time based on the parameters for determining the power loss by the offset processing. It becomes possible to operate more appropriately.

(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 motor mounted on a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of the hybrid vehicle power transmission system.

  As shown in the figure, the power of the internal combustion engine 1 is distributed to the first motor generator (generator 4) and the second motor generator (electric motor 5) via the power split mechanism 3. Specifically, the power split mechanism 3 includes a planetary gear mechanism. The planetary gear 3p is an output shaft of the internal combustion engine 1, the sun gear 3s is a rotating shaft of the generator 4, and the ring gear 3r is an electric motor 5. Are connected to the rotating shafts of each. The generator 4 and the electric motor 5 are both constituted by DC brushless motors.

  The load torque of the generator 4 and the output torque of the electric motor 5 are controlled by the power control unit 6. A battery 7 is connected to the power control unit 6. Then, the generated energy of the generator 4 is charged into the battery 7 via the power control unit 6, and the electric motor 5 is operated by the electric power of the battery 7. The output torque of the electric motor 5 is transmitted to the drive wheels 8 of the vehicle.

  FIG. 2 shows a part related to the control of the electric motor 5 in the power control unit 6.

  As illustrated, an inverter 10 is connected to three phases (U phase, V phase, and W phase) of the electric motor 5. 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, 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 where the switching element 12 and the switching element 14 are connected in series is connected to the U phase of the electric motor 5. A connection point for connecting the switching element 16 and the switching element 18 in series is connected to the V phase of the electric motor 5. 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 5. Incidentally, in the present embodiment, these switching elements 12 to 22 use elements that regulate the flow direction of current between the input terminal and the output terminal in one direction. Specifically, the switching elements 12 to 22 are constituted by insulated gate bipolar transistors (IGBT).

  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.

  On the other hand, the controller 50 includes a position sensor 52 that detects the rotation angle of the output shaft of the electric motor 5, current sensors 54 and 56 that detect current flowing in the U phase and the V phase, and a voltage sensor 58 that detects the voltage of the battery 7. Capture detection results. Then, the controller 50 calculates the current flowing in the W phase from the current flowing in the U phase and the current flowing in the V phase based on Kirchhoff's law. Then, the controller 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 5 and the respective currents flowing through the three phases.

  FIG. 3 shows a block diagram of processing performed by the controller 50. In the present embodiment, the output torque of the electric motor 5 is controlled to the required torque by PWM control. Below, the process regarding PWM control at the time of normal among the processes shown in FIG. 3 is demonstrated first.

  The two-phase conversion unit 80 includes the actual current iu flowing through the U phase and the actual current iv flowing through the V phase detected by the current sensors 54 and 56, and the actual current iw flowing through the W phase calculated based on these. This is a part for generating the actual current id and the actual current iq by converting the coordinates to the dq axis. Incidentally, since the rotation angle θ of the electric motor 5 (more precisely, θ is an electrical angle) is used for this coordinate conversion, the two-phase conversion unit 80 has a rotation angle θ detected by the position sensor 52. Entered. On the other hand, the command current setting unit 82 is a part that generates command currents iqc and idc in accordance with the required torque and the like. The command currents iqc and idc are current command values on the dq axis.

  The command voltage setting unit 84 calculates the command voltage vdc based on the command current idc and the actual current id, and calculates the command voltage vqc based on the command current iqc and the actual current iq. Specifically, for example, the sum of the proportional term and the integral term based on the difference between the command current idc and the actual current id is set as the command voltage vdc, and the sum of the proportional term and the integral term based on the difference between the command current iqc and the actual current iq is used. The command voltage vqc may be calculated based on this.

  The three-phase converter 86 converts the d-axis command voltage vdc and the q-axis command voltage vqc into a U-phase command voltage vuc1, a V-phase command voltage vvc1, and a W-phase command voltage vwc1. These command voltages vuc1, vvc1, and vwc1 are voltages to be applied to each phase when a three-phase command current corresponding to the command currents idc and iqc is supplied to each phase of the electric motor 5. These command voltages vuc1, vvc1, and vwc1 are sine waves and the centers of the voltages are zero. The command current of each phase of the electric motor 5 means a command current in each of the three phases determined by the command currents idc and iqc.

  These command voltages vuc1, vvc1, and vwc1 are applied to the non-inverting input terminals of the comparators 90, 92, and 94 via the switching unit 88, respectively. Comparators 90, 92, and 94 compare the command voltages vuc, vvc, and vwc with the triangular carrier generated by the carrier generation unit 96. The output signals gu, gv, gw of these comparators 90, 92, 94 are pulse width modulation (PWM) signals.

  The output signals gu, gv, gw and their inverted signals by the inverters 96, 98, 100 are taken into the Deadtime generator 102. The deadtime generation unit 102 shapes the waveform of each of the output signals and the inverted signal corresponding to the output signals so as to avoid timing overlap between these 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.

  FIG. 4 shows the transition of the duty, which is the ratio of the on time to the on / off period of each of the switching elements 12 to 22 by the PWM control. Specifically, FIG. 4A shows the relationship between the command voltages vuc1, vvc1, and vwc1 and the carrier cs, FIG. 4B shows the transition of the output signal gu, and FIG. 4C shows the output. The transition of the signal gv is shown, and FIG. 4D shows the transition of the output signal gw. As shown in the figure, output signals gu, gv, and gw are applied to the motor 5 through the inverter 10 to apply the command voltages vuc1, vvc1, and vwc1 as the command voltages vuc1, vvc1, and vwc1 change periodically. Calculated. As a result, voltages corresponding to the command voltages vuc 1, vvc 1, vwc 1 are applied to the electric motor 5 via the inverter 10.

  By the way, when the rotational speed of the electric motor 5 decreases, the period of the rotational angle θ of the electric motor 5 becomes very long with respect to the period of the carrier cs, or the time differential value (rotational speed ω) of the rotational angle θ is zero. It becomes. In this case, as shown in FIG. 5, since the command voltages vuc1, vvc1, and vwc1 are substantially constant (or fixed), the duty of the output signals gu, gv, and gw is fixed, and thus each switching element. There is a concern that the switching duty of 12 to 22 may be fixed. At this time, the average current value flowing through the specific switching element becomes excessively large, and as a result, the power loss of the switching element may be excessively increased. In particular, since the electric motor 5 is connected to the drive wheel 8, for example, when traveling on a steep climbing lane or when the drive wheel 8 rides on a protrusion on the road surface, the rotational speed of the drive wheel 8 becomes substantially zero. In addition, the output torque of the electric motor 5 at that time may be the maximum output torque. At this time, since the time during which the maximum current flows in a specific phase of the electric motor 5 increases, an increase in power loss of the specific switching element becomes particularly significant.

  Therefore, in the present embodiment, as shown in FIG. 2, the offset processing unit 110 and the two-phase modulation unit 112 are provided, and when the rotation speed of the electric motor 5 is equal to or lower than a predetermined speed, processing by these is adopted when operating the inverter 10. To do.

  FIG. 6 shows the processing of the offset processing unit 110. This process is repeatedly executed at a predetermined cycle, for example.

  In this series of processing, first, in step S10, it is determined whether or not the sign of the command voltage vuc1, vvc1, vwc1 having the maximum absolute value is positive. This processing is performed between the switching element (switching elements 12, 16, and 20) for conducting the electric motor 5 and the positive electrode potential side of the inverter 10 and the switching element (switching elements 14, 18, and 22) for conducting the negative electrode potential and the electric motor 5. Of these, the one with the largest power loss is specified. When it is determined in step S10 that the sign is positive, the process proceeds to step S12. Here, it is assumed that the element with the largest power loss is a switching element that conducts the positive electrode potential side of the inverter 10 and the electric motor 5, and the command voltages vuc1, vvc1, and vwc1 are corrected to decrease. On the other hand, when it is determined that the sign is negative, the process proceeds to step S14. Here, the command voltage vuc1, vvc1, vwc1 is increased and corrected, assuming that the power loss is maximized as a switching element that connects the negative electrode potential side of the inverter 10 and the electric motor 5. When the processes in steps S12 and S14 are completed, this series of processes is temporarily terminated.

  FIG. 7 shows processing of the two-phase modulation unit 112. This process is repeatedly executed at a predetermined cycle, for example.

  In this series of processes, first, in step S20, it is determined whether or not the command voltage vuc1, vvc1, or vwc1 has the maximum absolute value is the U-phase command voltage vuc1. This process is for determining whether or not the phase having the switching element that maximizes the power loss is the U phase. When it is determined in step S20 that the command voltage is vuc1, the process proceeds to step S22 in order to fix the switching operation of the U-phase arm in the two-phase modulation process. In step S22, it is determined whether or not command voltage vuc1 is positive. This process is for identifying the switching elements 12 and 14 of the U-phase arm that are fixed in the on state and those that are fixed in the off state.

  When it is determined in step S22 that the command voltage vuc1 is positive, the process proceeds to step S24. Here, in order to fix the switching element 12 on the positive side of the inverter 10 in the on state and the switching element 14 on the negative side in the off state, the command voltage vuc1 is set to the voltage VB of the battery 7 that is the input voltage of the inverter 10. "1/2". At the same time, the command voltages vvc and vwc are corrected so as to maintain the interphase voltage determined by the command voltages vuc1, vvc1 and vwc1. Specifically, the command voltages vvc and vwc are corrected to a value obtained by adding the difference between the command voltage vuc1 and the command voltage vuc1 to the command voltages vvc1 and vwc1. On the other hand, when it is determined in step S22 that the command voltage vuc1 is negative, the process proceeds to step S26. Here, in order to fix the switching element 12 on the positive side of the inverter 10 in the off state and the switching element 14 on the negative side in the on state, the command voltage vuc1 is set to the voltage VB of the battery 7 which is the input voltage of the inverter 10. "-1/2". At the same time, the command voltages vvc and vwc are corrected so as to maintain the interphase voltage determined by the command voltages vuc1, vvc1 and vwc1.

  When a negative determination is made in step S20, it is determined in step S28 whether or not the command voltage vuc1, vvc1, or vwc1 has the maximum absolute value is the V-phase command voltage vvc1. This process determines whether or not the phase having the switching element that maximizes the power loss is the V phase. When it is determined in step S28 that the command voltage is vvc1, the processes in steps S30 to S34 are performed. The processes in steps S30 to S32 are processes in which the U phase and the V phase are switched in steps S22 to S26.

  When a negative determination is made in step S28, it is considered that the phase that fixes the switching operation is the W-phase arm in the two-phase modulation process. Therefore, steps S36 to S40 are performed. The processes in steps S36 to S40 are processes in which the U phase and the W phase are interchanged in the processes in steps S22 to S26.

  In addition, when the process of said step S24, S26, S32, S34, S38, S40 is completed, this series of processes will be once complete | finished.

  FIG. 8A shows power loss of the switching elements 12 to 22 and the flywheel diodes 24 to 34 due to the offset processing and the two-phase modulation processing. FIG. 8 shows switching of power loss (on loss) and on / off in the on state of the switching elements 12 to 22 having the largest power loss when the switching frequency is, for example, “1.25 kHz”. This power loss (switching loss) and the power loss of the flywheel diodes 24-34 are shown.

  As shown in the figure, when performing two-phase modulation, the power loss of the switching element that is turned on in the phase having the maximum absolute value among the command voltages vuc1, vvc1, and vwc1 is “900 W”. The power loss of this phase flywheel diode is zero. This is due to the following reason.

  9A and 9B show the case where the U-phase command voltage vuc is fixed to the positive potential side of the battery B when the power loss of the switching element 12 on the positive phase side of the U phase is maximized. Illustrated. As shown in the drawing, when the switching element 12 on the positive side of the U-phase arm is in the ON state, the switching element 12 is switched in the U-phase regardless of the operation mode of the switching elements 16 to 22 of the V-phase and the W-phase. Current flows through the other elements, and no current flows through the other elements. For this reason, the power loss of the flywheel diodes 24 and 26 of the U-phase arm is also zero. In the figure, the switching elements 16 and 20 on the positive side of the V-phase arm and the W-phase arm are illustrated as being on, and the switching elements 18 and 22 on the negative side are illustrated as being on. In some cases, the positive-side switching element and the negative-side switching element of either the V-phase arm or the W-phase arm are turned on. Further, even when the power loss of the U-phase switching element 14 is the maximum, or even when the power loss is the maximum in the V phase and the W phase, it can be basically considered in the same manner. I will omit the explanation.

  On the other hand, as shown in FIG. 8A, when the duty of the phase where the power loss is maximum is 52%, the switching element in which the largest current flows is the sum of the on loss and the switching loss. The power loss is “770 W”. On the other hand, when the duty is set to “30%”, the power loss of the switching element is reduced to “580 W”. However, in this case, the power loss of the flywheel diode increases from “460 W” to “670 W”. This is due to the following reason.

  9 (c) and 9 (d) both show that when the power loss of the switching element 12 on the positive side of the U phase is maximized, the duty is set at the offset voltage Δ in order to reduce the power loss of the switching element 12. The case where the reduction is corrected is shown. In this case, the on-time of the switching element 12 on the positive side of the U-phase arm decreases due to the offset, and when this is in the off state, a current flows through the flywheel diode 26 on the negative side of the U-phase arm. For this reason, although the power loss of the switching element 12 can be reduced, the power loss of the flywheel diode 26 increases.

  In this embodiment, when the rotational speed ω is equal to or lower than the predetermined speed, the two processes are alternately performed while switching between the two-phase modulation process and the offset process via the switching unit 88 shown in FIG. Do. Specifically, a process of periodically switching between these two processes is performed. Accordingly, it is possible to perform more appropriate processing while suppressing an excessive increase in power loss of a specific one of the switching elements 12 to 22. For example, as illustrated in FIG. 8B, by setting the two-phase modulation processing time and the offset processing time to the same time, the loss of the switching element that maximizes the power loss is reduced to “740 W”, and The loss of the flywheel diode in that phase can be reduced to “335 W”.

  The time distribution (ratio) of these two-phase modulation processing and offset processing can be appropriately determined according to the requirements at the time of designing the inverter 10 and the like. For example, in the existing inverter 10 that can withstand power loss at extremely low speed, when the design is given priority to downsizing of the switching element, the power loss of the flywheel diode may be the same as before. Therefore, the power loss of the switching element may be set to be reduced as much as possible under the condition that the maximum value of the power loss of the flywheel diode at the extremely low speed is less than the allowable maximum value of the power loss of the conventional flywheel diode.

  For this reason, the time distribution may be determined as shown in FIG. That is, for example, if the power loss of the flywheel diode due to normal duty control at extremely low speeds is maximum “460 W” at the duty “52%”, the loss of the flywheel diode caused by the combined use of the two-phase modulation processing and offset processing is The power loss of the switching element may be reduced as much as possible while setting the loss to “460 W” or less. Here, the loss of the flywheel diode increases as the duty decreases, and the power loss of the switching element decreases as the duty decreases. Therefore, the loss of the flywheel diode can be set to “460 W”. It is considered that the loss of the switching element can be reduced most when the time distribution is set to. Therefore, in FIG. 8C, the offset processing time ratio α is set so that the loss of the flywheel diode becomes the maximum value of normal duty control. Thereby, the loss of the switching element can be reduced to “679 W”.

  In practice, not only time distribution but also one period of time is set as appropriate. Here, for example, when the two-phase modulation processing time is excessively long, the temperature rise of the switching elements 12 to 22 becomes remarkable, and when the offset processing time is excessively long, the temperature increase of the flywheel diodes 24 to 34 is remarkable. In view of the above, the setting is made to avoid these situations.

  FIG. 10 shows a procedure of processing at an extremely low speed according to the present embodiment. This process is repeatedly executed in the controller 50 at a predetermined cycle, for example.

  In this series of processes, first, in step S50, it is determined whether or not the rotational speed ω is equal to or lower than a predetermined speed N. Here, the predetermined speed N is set according to a speed at which the power loss of a specific switching element is assumed to be excessive by fixing the duty. And if it is judged that it is below the predetermined speed N, it will transfer to step S52. In step S52, the counter I that counts the time from the start of the two-phase modulation process is incremented. In a succeeding step S54, it is determined whether or not the counter I is larger than the two-phase modulation processing time T2P. When it is determined that the time is equal to or shorter than the two-phase modulation processing time T2P, the process proceeds to step S56. In step S56, the two-phase modulation process shown in FIG. 7 is performed.

  On the other hand, when it is determined in step S54 that the counter I is greater than the two-phase modulation processing time T2P, the process proceeds to step S58. In step S58, it is determined whether counter I is longer than offset processing time Tcy. The offset processing time Tcy is actually the sum of the two-phase modulation processing time T2P and the time for offset processing. And when it is judged that it is below offset processing time Tcy, it shifts to Step S60. In step S60, the offset process shown in FIG. 6 is performed.

  On the other hand, when it is determined in step S50 that the rotational speed ω is greater than the predetermined speed N, or when it is determined in step S58 that it is longer than the offset processing time Tcy, the process proceeds to step S62. In step S62, the counter I is set to zero.

  When the processes in steps S56, S60, and S62 are completed, this series of processes is temporarily terminated.

  FIG. 11 illustrates an example of the above processing. Specifically, FIG. 11A shows the transition of the rotation angle θ, FIG. 11B shows the transition of the offset voltage, FIG. 11C shows the transition of the command voltage, and FIG. ) Shows the transition of the operation mode of the switching elements 12-22. Here, the case where the power loss of the switching element 12 on the positive electrode side of the U-phase arm is maximized is illustrated.

  In this case, in the two-phase modulation process, the command voltage vuc of the U-phase arm is fixed to the positive electrode side, and in the offset process, the duty is reduced. Thereby, in the two-phase modulation process and the offset process, the offset voltages for correcting the command voltages vuc1, vvc1, and vwc1 have opposite signs.

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

  (1) When the rotational speed ω is equal to or lower than the predetermined speed N, the power loss determined by the command voltages vuc1, vvc1, and vwc1 among the switching elements 12 to 22 is maximized. Offset processing for adding a predetermined offset voltage Δ to the command voltages vuc1, vvc1, and vwc1 was performed. Thereby, the ON time of the specific switching element can be reduced. Furthermore, by adding a common offset voltage Δ to the command voltages vuc1, vvc1, and vwc1, it is possible to maintain an interphase voltage determined by the command voltages vuc1, vvc1, and vwc1 before the addition of the offset voltage Δ.

  (2) When the rotational speed ω is equal to or lower than the predetermined speed N, the power loss is maximized by correcting the command voltages vuc1, vvc1, and vwc1 while maintaining the interphase voltages determined by the three-phase command voltages vuc1, vvc1, and vwc1. The on / off state of the phase switching element having the switching element is fixed. As a result, the power loss of the phase flywheel diode having the switching element that maximizes the power loss can be reduced. In addition, as shown in FIG. 8, the two-phase modulation processing tends to reduce the total power loss of the inverter 10 as compared with the normal processing and offset processing. The power loss of the inverter 10 can also be reduced.

  (3) When the rotational speed ω is equal to or lower than the predetermined speed N, the two processes of the two-phase modulation process and the offset process are periodically switched. Accordingly, it is possible to reduce the power loss of the switching element while suppressing an increase in the power loss of the phase flywheel diode having the switching element that maximizes the power loss.

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

  FIG. 12 is a block diagram showing processing performed by the controller 50 according to the present embodiment. In FIG. 12, members corresponding to those shown in FIG. 3 are given the same reference numerals for convenience.

  In this embodiment, the time distribution of the two-phase modulation process and the offset process is variably set according to at least one of the following parameters.

  Element temperature: This is a parameter used when determining the time distribution from the viewpoint that the optimal time distribution changes according to the temperature of the switching elements 12 to 22 and the flywheel diodes 24 to 34. Here, for example, the distribution of the two-phase modulation processing time may be increased as the temperature of the flywheel diodes 24 to 34 is higher, preferably as the maximum value of the temperature of the flywheel diodes 24 to 34 is higher. Further, for example, the higher the temperature of the switching elements 12 to 22, and preferably the higher the maximum temperature of the switching elements 12 to 22, the larger the distribution of the offset processing time may be.

  Duty: As the duty determined by the command voltages vuc1, vvc1, and vwc1 is farther from “50%”, the maximum value of the power loss still tends to be larger even by the offset voltage Δ. For this reason, for example, the distribution of the offset processing time may be increased as the duty is larger. Also, the magnitudes of power loss during the offset process may differ depending on the absolute values of the command voltages vuc, vvc, and vwc after correction using the offset voltage. For this reason, the distribution may be variably set according to the duty determined by the command voltages vuc, vvc, vwc after correction by the offset voltage.

  Command voltage: The maximum value of the power loss after the correction of the command voltage vuc1, vvc1, vwc1 by the offset voltage Δ tends to increase as the absolute value of the command voltage vuc1, vvc1, vwc1 becomes maximum. For this reason, for example, the distribution of the offset processing time may be increased as the maximum absolute value increases. Also, the magnitudes of power loss during the offset process may differ depending on the absolute values of the command voltages vuc, vvc, and vwc after correction using the offset voltage. For this reason, the distribution may be variably set according to the absolute values of the command voltages vuc, vvc, vwc after correction by the offset voltage.

  Offset voltage Δ... The degree of reduction in power loss during offset processing depends on the offset voltage Δ. For this reason, the distribution may be variably set according to the offset voltage Δ.

  Real currents iu, iv, iw... Power loss depends on the magnitudes of real currents iu, iv, iw. Therefore, the distribution may be variably set according to these.

  Rotation angle θ... Vuc1, vvc1, vwc1 and actual currents iu, iv, iw of each phase depend on the rotation angle θ. For this reason, the distribution may be variably set according to the rotation angle.

  By using these several parameters together, it is possible to set the distribution more appropriately. For example, when the offset voltage Δ is variably set according to the rotation angle θ or the like as in Patent Document 1, it is considered that the power loss can vary depending on the maximum absolute value of the command voltages vuc1, vvc1, and vwc1. Absent. For this reason, in order to take these into account, the distribution is variably set according to the maximum absolute value of the offset voltage Δ and the command voltages vuc1, vvc1, and vwc1, thereby performing more appropriate processing for reducing power loss. Can do.

  According to this embodiment described above, in addition to the effects (1) to (3) in the first embodiment, the following effects can be obtained.

  (4) Two-phase modulation processing and offset according to at least one of the element temperature of the inverter 10, the duty, the command voltage, the rotation angle θ of the motor 5, the actual currents iu, iv, iw flowing through the motor 5, and the offset voltage Δ The time allocation with the process was variably set. Thereby, inverter 10 can be operated more appropriately.

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

  In the second embodiment, according to at least one of the element temperature of the inverter 10, the duty, the command voltage, the rotation angle θ of the motor 5, the actual currents iu, iv, iw flowing through the motor 5, and the offset voltage Δ. Although the time distribution between the offset process and the two-phase modulation process is variably set, this is not restrictive. For example, based on these parameters, one processing time (one cycle) consisting of offset processing and two-phase modulation processing may be variably set.

  The processing time settings for the two-phase modulation process and the offset process are not limited to those exemplified in the above embodiments. For example, when it is desired to make the switching elements 12 to 22 as small as possible, the flywheel diodes 24 to 34 are enlarged, and the maximum power loss of the switching elements 12 to 22 is reduced as much as possible based on the allowable maximum power loss at this time. And it is sufficient. Further, for example, there is a restriction that the maximum power loss of the flywheel diodes 24 to 34 is limited to be equal to or less than the maximum power loss of the flywheel diodes 24 to 34 when the two-phase modulation processing and the offset processing are performed at times other than extremely low speed. Below, it is good also as a setting which reduces the maximum electric power loss of switching element 12-22 as much as possible.

  In each of the above embodiments, the two-phase modulation process and the offset process are used together, but this is not a limitation. Here, according to the two-phase modulation process, there is an advantage that the power loss of the inverter 10 can be reduced and the power loss of the flywheel diodes 24 to 34 can be reduced, but the power of the switching elements 12 to 22 is reduced. It is desirable to take into account the disadvantage of increased loss. For example, it is possible to reduce the power loss of the flywheel diodes 24 to 34 while suppressing the increase of the power loss of the switching elements 12 to 22 by combining two-phase modulation processing and normal processing, Power loss can be reduced.

  By combining the offset process that performs correction using the offset voltage Δ and the process that does not perform the correction, the degree of freedom of the process can be increased as compared with the case of using only the offset process. For example, in view of the characteristics shown in FIG. 8A, the process of reducing the power loss of the switching elements 12 to 22 while suppressing the increase of the power loss of the flywheel diodes 24 to 34 as much as possible by the combined use of the above processes. Etc.

  The switching element is not limited to the IGBT but may be a MOS transistor, for example. The rectifying means connected in antiparallel with the IGBT is not limited to a diode, and may be a thyristor, for example.

  The three-phase rotating machine is not limited to a three-phase motor, and may be a three-phase generator.

  In each of the above embodiments, the control device according to the present invention is mounted on the in-vehicle hybrid system. However, the present invention is not limited thereto, and may be mounted on, for example, an electric vehicle.

The figure which shows the whole structure of the vehicle-mounted hybrid system concerning 1st Embodiment. The figure which shows the whole structure of the control system of the electric motor concerning the embodiment. The block diagram which shows the process of the controller concerning the embodiment. The time chart which shows the aspect of a PWM modulation process. The time chart which shows the PWM modulation | alteration mode at the time of very low speed. The flowchart which shows the procedure of the offset process concerning the said embodiment. The flowchart which shows the procedure of the two-phase modulation process concerning the embodiment. The figure which shows combined use with the offset process and the two-phase modulation process concerning the embodiment. The figure which shows the flow aspect of the electric current in the offset process and 2 phase modulation | alteration process concerning the embodiment. The flowchart which shows the procedure of the switching process of the offset process and 2 phase modulation process concerning the embodiment. The time chart which shows the aspect of the said switching process. The block diagram which shows the process of the controller concerning 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 5 ... Electric motor, 12-22 ... Switching element, 24-34 ... Flywheel diode (one Embodiment of a rectification | straightening means), 50 ... Controller (control apparatus of a three-phase rotary machine).

Claims (4)

In a control device for a three-phase rotating machine that operates each switching element of the inverter by duty control according to a command voltage for each phase of the three-phase rotating machine,
Three-phase modulation processing means for operating each of the three-phase switching elements by the duty control;
When the command voltage with the maximum absolute value is positive among the command voltages for each phase, the command voltage for each phase is corrected by an amount necessary to use the command voltage as the voltage of the positive input terminal of the inverter. Two-phase modulation processing means for correcting the command voltage of each phase by an amount necessary for setting the command voltage to the voltage of the negative input terminal of the inverter when the absolute value is the maximum. ,
When the rotational speed of the three-phase rotating machine is equal to or lower than a predetermined speed, when the switching element is operated, switching between the processing by the three-phase modulation processing means and the processing by the two-phase modulation processing means is performed. Switching means that uses processing together,
When the processing by the three-phase modulation processing means is performed by switching by the switching means, the command voltage is corrected with an offset voltage having a reverse sign to that by the two-phase modulation processing means. Machine control device.   2. The control device for a three-phase rotating machine according to claim 1, wherein the switching by the switching means is performed in a shorter period than when the electrical angle of the three-phase rotating machine changes by “60 °”. The switching element is an element that regulates the flow direction of current between the input terminal and the output terminal in one direction,
The inverter control device of the three-phase rotary machine according to claim 1 or 2, wherein the obtaining further Bei the connected rectifying means in antiparallel with the switching element.   The switching unit is configured to perform the operation according to at least one of the element temperature of the inverter, the duty, the command voltage, the rotation angle of the three-phase rotating machine, the actual current flowing through the three-phase rotating machine, and the offset voltage. The control device for a three-phase rotating machine according to any one of claims 1 to 3, wherein each processing time of the processing by the phase modulation processing means and the processing by the two-phase modulation processing means is variably set.

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