JP2018125958A - Control apparatus of pole change electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control apparatus of a pole change electric motor capable of reducing a peak value of voltage to be generated in changing of the number of poles.SOLUTION: A control apparatus is applied to a system with: an electric motor capable of changing the number of poles; and an inverter electrically connected with the electric motor. The control apparatus gradually reduces command torque before change toward zero and gradually increases command torque after change toward a value larger than zero in a pole change period TC. The control apparatus performs at least one of processing of increasing excitation current corresponding to the number of poles after change and processing of reducing excitation current corresponding to the number of poles before change prior to start timing of the pole change period.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a motor control device capable of switching the number of poles.

  As this type of control device, as disclosed in Patent Document 1, there is known a device that suppresses torque shock of an electric motor at the time of switching the number of poles. Specifically, for example, when switching from 8 poles to 4 poles, this control device supports 8 poles while keeping the total command torque of the command torque corresponding to 8 poles and the command torque corresponding to 4 poles constant. The command torque to be gradually reduced and the command torque corresponding to the four poles is gradually increased.

JP-A-8-223999

  Even if the control method described in Patent Document 1 is used, there may be a problem that the peak value of the voltage generated in the electric motor becomes large at the time of switching the number of poles. For this reason, there is a restriction that the number of poles can be switched only when the load of the motor is low, for example. In order to eliminate this restriction, a method of reducing the total command torque at the time of switching the number of poles in order to reduce the peak value of the voltage can be considered. However, in this case, there may be a disadvantage that the actual generated torque of the electric motor does not satisfy the required torque.

  The main object of the present invention is to provide a control device for a pole number switching motor that can reduce the peak value of the voltage generated at the time of pole number switching while avoiding the above-mentioned inconvenience.

  The present invention is applied to a system including an electric motor (10) whose number of poles can be switched, and an inverter (20; 26A, 26B) electrically connected to the electric motor, and an integer of 3 or more is m, In the case where n is an integer of 2 or more, the motor has n sets of m-phase stator windings (12A to 12F), and in the case where A is an even number of 2 or more, the A pole and the n × A pole Is defined as the number of poles before switching, and the other is defined as the number of poles after switching.

  The present invention controls the pre-switching torque, which is the torque of the motor corresponding to the pre-switching pole number, to the pre-switching command torque, and the post-switching torque, which is the torque of the motor corresponding to the post-switching pole number In order to control the command torque after switching, the inverter operating unit (32 to 35) that operates the inverter, and in the pole switching period, the command torque before switching is gradually decreased toward 0, and A switching unit (31; 36) for gradually increasing the command torque after switching toward a value larger than 0, and the secondary magnetic flux of the motor corresponding to the number of poles before switching is the secondary magnetic flux before switching. Defined, the current flowing through the motor to generate the secondary magnetic flux before switching is defined as the pre-switching excitation current, and the secondary magnetic flux of the motor corresponding to the post-switching pole number is defined as the secondary magnetic flux after switching. Is, the current flowing through the electric motor to produce a secondary magnetic flux after the switching is defined as the post-switching exciting current. The switching unit performs at least one of a process of increasing the post-switching excitation current and a process of decreasing the pre-switching excitation current prior to the start timing of the pole number switching period.

  The present invention includes an inverter operation unit that operates an inverter to control the pre-switching torque to the pre-switching command torque and to control the post-switching torque to the post-switching command torque. In the present invention, in order to reduce the torque shock at the time of switching the number of poles, the command torque before switching is gradually decreased toward 0 and the command torque after switching is larger than 0 in the period of switching the number of poles. The switching part which increases gradually toward is provided.

  Here, as a configuration to be compared with the present invention, a configuration that starts increasing the post-switching excitation current together with the post-switching command torque at the start timing of the pole number switching period is referred to as Comparative Example 1.

  The torque of the electric motor is determined based on the torque current flowing through the electric motor and the secondary magnetic flux of the electric motor. The responsiveness of the rising change of the secondary magnetic flux after switching accompanying the rising change of the excitation current after switching is lower than the responsiveness of the torque current. For this reason, in Comparative Example 1, the post-switching excitation current is sharply increased from the start timing of the pole number switching period. However, as in the first comparative example, if the excitation current after switching is increased sharply from the start timing of the pole number switching period, the applied voltage of the motor is rapidly increased. As a result, the peak value of the voltage generated in the electric motor at the time of switching the number of poles becomes large.

  Therefore, the switching unit of the present invention performs a process of increasing the post-switching excitation current prior to the start timing of the pole number switching period. For this reason, before starting to increase the command torque after switching, it is possible to increase the secondary magnetic flux after switching by increasing the excitation current after switching. This eliminates the need to sharply increase the excitation current after switching as in Comparative Example 1. As a result, the peak value of the voltage generated in the electric motor can be reduced.

  Further, as a configuration to be compared with the present invention, at the start timing of the pole number switching period, the pre-switching excitation torque and the pre-switching torque current corresponding to the pre-switching command torque are reduced together with the pre-switching command torque. The starting configuration is referred to as Comparative Example 2.

  As in Comparative Example 2, if the pre-switching excitation current and the pre-switching torque current are to be decreased together with the pre-switching command torque from the start timing of the pole number switching period, the applied voltage of the motor is gently lowered. At the time of switching the number of poles, the peak value of the voltage generated by the motor becomes large because the voltage rises sharply due to the current fluctuation after switching under the situation where the slow voltage falling due to the current fluctuation before switching occurs. .

  Therefore, the switching unit of the present invention reduces the pre-switching excitation current prior to the start timing of the pole number switching period. By reducing the excitation current before switching, the peak value of the voltage generated in the motor can be reduced prior to the start timing of the pole number switching period. In addition, since the present invention includes a configuration for performing a process of increasing the pre-switching torque current along with the decrease of the pre-switching excitation current, it is possible to suppress a torque decrease due to the decrease of the pre-switching excitation current. Since the responsiveness of the lowering change of the secondary magnetic flux before switching accompanying the lowering change of the exciting current before switching is lower than the responsiveness of the torque current, the increase in the torque current before switching becomes smaller with respect to the decrease in the exciting current before switching. Thereby, the increase in the peak value of the current flowing through the electric motor can be suppressed.

1 is an overall configuration diagram of an in-vehicle motor control system according to a first embodiment. The figure which shows a stator winding | coil. The block diagram which shows the vector control which a control apparatus performs. The time chart which shows the process at the time of pole number switching. The time chart which shows the increase aspect of d-axis current. The time chart which shows the decreasing aspect of d-axis current. The time chart which shows the process at the time of the pole number switching in a comparison technique. The time chart which shows the reduction effect of peak values, such as a phase voltage. The block diagram which shows the vector control which the control apparatus which concerns on 2nd Embodiment performs. The whole block diagram of the vehicle-mounted motor control system which concerns on 3rd Embodiment. The time chart which shows the increase aspect of d-axis current which concerns on other embodiment.

(First embodiment)
Hereinafter, a first embodiment in which a control device according to the present invention is applied to a vehicle such as an electric vehicle or a hybrid vehicle including an electric motor as an in-vehicle main unit will be described with reference to the drawings.

  As shown in FIG. 1, the in-vehicle control system includes a motor 10, an inverter 20, and a control device 30.

  The motor 10 is an in-vehicle main machine and can transmit power to the drive wheels 40. In the present embodiment, the motor 10 is a squirrel-cage induction motor whose number of poles can be switched. Specifically, the motor 10 is configured to be able to switch the number of poles to either 4 or 8 poles. An induction motor whose number of poles can be switched is also called a pole change motor.

  In the present embodiment, the stator 11 of the motor 10 includes six-phase windings 12A to 12F. The windings 12A to 12F are provided on the stator 11 so as to be shifted by 60 degrees in electrical angle.

  In the present embodiment, as shown in FIG. 2, the stator 11 is provided with a first winding group and a second winding group. The first winding group includes an A-phase winding 12A, a C-phase winding 12C, and an E-phase winding 12E. The second winding group includes a B-phase winding 12B, a D-phase winding 12D, and an F-phase winding 12F. The first ends of the A-phase winding 12A, the C-phase winding 12C, and the E-phase winding 12E are connected at a first neutral point N1. The A-phase winding 12A, the C-phase winding 12C, and the E-phase winding 12E are provided on the stator 11 in a state that they are shifted from each other by 120 degrees in electrical angle. The first ends of the B-phase winding 12B, the D-phase winding 12D, and the F-phase winding 12F are connected at a second neutral point N2. The B-phase winding 12B, the D-phase winding 12D, and the F-phase winding 12F are provided on the stator 11 in a state where they are shifted from each other by 120 degrees in electrical angle. In the present embodiment, the first winding group and the second winding group are provided on the stator 11 so as to be shifted by 60 degrees in electrical angle. For this reason, each phase winding 12A-12F is provided in the stator 11 so that an electrical angle may change 60 degree | times in order of A, B, C, D, E, and F phase.

  Returning to the description of FIG. 1, the motor 10 is connected to a battery 21 as a DC power source via a six-phase inverter 20. The inverter 20 includes a series connection body of upper arm switches and lower arm switches for six phases. The second end of the A-phase winding 12A is connected to the connection point PA of the A-phase upper and lower arm switches SAp and SAn, and the connection point PB of the B-phase upper and lower arm switches SBp and SBn is connected to B The second end of the phase winding 12B is connected, and the second end of the C-phase winding 12C is connected to the connection point PC of the C-phase upper and lower arm switches SCp, SCn. The second end of the D-phase winding 12D is connected to the connection point PD of the D-phase upper and lower arm switches SDp and SDn, and the connection point PE of the E-phase upper and lower arm switches SEp and SEn is connected to E The second end of the phase winding 12E is connected, and the second end of the F-phase winding 12F is connected to the connection point PF of the F-phase upper and lower arm switches SFp, SFn.

  Each switch SAp to SFn may be a voltage-controlled semiconductor switching element such as an IGBT or an N-channel MOSFET. In addition, a diode is connected in antiparallel to each of the switches SAp to SFn.

  The control system includes a current sensor 22 and a speed sensor 23. The current sensor 22 detects each phase current flowing through the motor 10. In FIG. 1, detected values of currents flowing in the A, B, C, D, E, and F phases are indicated by Iar, Ibr, Icr, Idr, Ier, and Ifr. The speed sensor 23 detects the mechanical angular frequency ωr of the rotor that constitutes the motor 10. Detection values of the current sensor 22 and the speed sensor 23 are input to the control device 30.

  The control device 30 is mainly composed of a microcomputer, and operates the inverter 20 to feedback control the torque of the motor 10 to the total command torque Tr *. The total command torque Tr * is output to the control device 30 from a control device higher than the control device 30, such as a control device that controls vehicle traveling control.

  The torque control of the motor 10 performed by the control device 30 will be described with reference to FIG.

  The control device 30 includes a command value calculation unit 31, a 4-pole control unit 32, an 8-pole control unit 33, and a coordinate conversion unit 34.

  The command value calculation unit 31 acquires the total command torque Tr * input from the outside, and based on the acquired total command torque Tr * and the mechanical angular frequency ωr detected by the speed sensor 23, the first command torque T4 *, second command torque T8 *, first command secondary magnetic flux φ4 * and second command secondary magnetic flux φ8 * are calculated. In the present embodiment, the first command torque T4 * is a command torque corresponding to 4 poles, and the second command torque T8 * is a command torque corresponding to 8 poles. In addition, the command value calculation unit 31 calculates the command torques T4 * and T8 * so that the added value of the first command torque T4 * and the second command torque T8 * becomes the total command torque Tr *.

  In this embodiment, the command value calculation unit 31 sets the first command torque T4 * and the first command secondary magnetic flux φ4 * to 0 when the number of poles of the motor 10 is selected, and sets the number of poles of the motor 10 as 0. When the 4-pole is selected, the second command torque T8 * and the second command secondary magnetic flux φ8 * are set to zero.

  The 4-pole control unit 32 is a current control system of the motor 10 when 4 poles are selected as the number of poles of the motor 10. The 8-pole control unit 33 is a current control system of the motor 10 when 8 poles are selected as the number of poles of the motor 10.

  First, the 4-pole control unit 32 will be described. The first frequency calculation unit 32a calculates a first electrical angular frequency ω4r that is an electrical angular frequency of the motor 10 corresponding to four poles, based on the mechanical angular frequency ωr and the number of poles P4 in the case of four poles. .

  The first magnetic flux estimator 32b includes the phase currents Iar to Ifr detected by the current sensor 22, the phase command voltages Va * to Vf * calculated by the coordinate converter 34, and the first electrical angular frequency ω4r. Based on the above, the secondary magnetic flux vector of the motor 10 corresponding to the four poles is estimated. This secondary magnetic flux vector is composed of a d-axis component and a q-axis component in the dq coordinate system corresponding to the four poles. In the present embodiment, this d-axis component is referred to as a first secondary magnetic flux φ4r. The 1st magnetic flux estimation part 32b should just be comprised by the well-known magnetic flux observer, for example.

  The dq coordinate system corresponding to the four poles is an orthogonal two-dimensional rotational coordinate system that rotates at the primary angular frequency that is the rotational angular frequency of the output voltage vector of the inverter 20. In the present embodiment, the positive direction of the d-axis serving as the phase reference is set to the direction of the secondary magnetic flux vector corresponding to the four poles estimated by the first magnetic flux estimating unit 32b.

  In the present embodiment, the control device 30 performs torque control under the condition that the q-axis component of the secondary magnetic flux vector is zero. This is because the d and q axis command currents cannot be uniquely determined only by giving the command torque.

  The first magnetic flux estimation unit 32b calculates a first electrical angle θ4 that is an electrical angle of the motor 10 corresponding to the four poles based on the estimated first secondary magnetic flux φ4r.

  The first dq converter 32c converts the phase currents Iar to Ifr to the first d-axis current Id4r and the first q-axis current Iq4r on the dq axis corresponding to the four poles based on the first electrical angle θ4. Here, the d-axis current is an excitation current for generating a secondary magnetic flux, and the q-axis current is a torque current. Note that the conversion in the first dq conversion unit 32c may be performed based on the following equation (eq1), for example. Here, the first transformation matrix C1 on the right side of the following equation (eq1) is represented by the following equation (eq2).

第１トルク推定部３２ｄは、第１の２次磁束φ４ｒと、各相電流Ｉａｒ〜Ｉｆｒとに基づいて、４極に対応するモータ１０のトルクである第１実トルクＴ４ｒを推定する。

The first torque estimating unit 32d estimates the first actual torque T4r that is the torque of the motor 10 corresponding to the four poles based on the first secondary magnetic flux φ4r and the phase currents Iar to Ifr.

  The first torque control unit 32e uses the first q-axis command current Iq4 on the q-axis as an operation amount for feedback-controlling the first actual torque T4r estimated by the first torque estimation unit 32d to the first command torque T4 *. * Is calculated. The feedback control used in the first torque control unit 32e may be, for example, proportional integral control.

  The first magnetic flux control unit 32f uses the first d on the d axis as an operation amount for performing feedback control of the first secondary magnetic flux φ4r estimated by the first magnetic flux estimation unit 32b to the first command secondary magnetic flux φ4 *. An axis command current Id4 * is calculated. Note that the feedback control used in the first magnetic flux control unit 32f may be proportional integral control, for example.

  The first current control unit 32g is an operation amount for performing feedback control of the first d-axis current Id4r converted by the first dq conversion unit 32c to the first d-axis command current Id4 * calculated by the first torque control unit 32e. The first d-axis command voltage Vd4 * on the d-axis is calculated. The first current control unit 32g performs an operation for feedback control of the first q-axis current Iq4r converted by the first dq conversion unit 32c to the first q-axis command current Iq4 * calculated by the first torque control unit 32e. As a quantity, the first q-axis command voltage Vq4 * on the q-axis is calculated. Note that the feedback control used in the first current control unit 32g may be proportional integral control, for example.

  Next, the 8-pole control unit 33 will be described. The second frequency calculation unit 33a calculates a second electrical angular frequency ω8r that is an electrical angular frequency of the motor 10 corresponding to 8 poles based on the mechanical angular frequency ωr and the pole number P8 in the case of 8 poles. .

  The second magnetic flux estimator 33b has eight poles based on the phase currents Iar to Ifr, the phase command voltages Va * to Vf * calculated by the coordinate converter 34, and the second electrical angular frequency ω8r. The secondary magnetic flux vector of the corresponding motor 10 is estimated. This secondary magnetic flux vector is composed of a d-axis component and a q-axis component in the dq coordinate system corresponding to the octupole. In the present embodiment, this d-axis component is referred to as a second secondary magnetic flux φ8r. The second magnetic flux estimator 33b may be configured by a known magnetic flux observer, for example.

  The dq coordinate system corresponding to 8 poles is an orthogonal two-dimensional rotating coordinate system that rotates at the primary angular frequency corresponding to 8 poles. In the present embodiment, the positive direction of the d-axis serving as the phase reference is set to the direction of the secondary magnetic flux vector corresponding to the eight poles estimated by the second magnetic flux estimation unit 33b.

  The second magnetic flux estimator 33b calculates a second electrical angle θ8 that is the electrical angle of the motor 10 corresponding to the eight poles based on the estimated second secondary magnetic flux φ8r.

  The second dq converter 33c converts the phase currents Iar to Ifr to a second d-axis current Id8r and a second q-axis current Iq8r on the dq axis corresponding to the eight poles based on the second electrical angle θ8. Note that the conversion in the second dq conversion unit 33c may be performed based on the following equation (eq3), for example. Here, the second transformation matrix C2 on the right side of the following equation (eq3) is represented by the following equation (eq4).

ちなみに、第１ｄｑ変換部３２ｃ及び第２ｄｑ変換部３３ｃにおける処理を一括して実施することもできる。この場合、各相電流Ｉａｒ〜Ｉｆｒは、下式（ｅｑ５）に基づいて変換されればよい。下式（ｅｑ５）の右辺の変換行列Ｄは、下式（ｅｑ６）で表される。

Incidentally, the processes in the first dq conversion unit 32c and the second dq conversion unit 33c can also be performed collectively. In this case, each phase current Iar to Ifr may be converted based on the following equation (eq5). The transformation matrix D on the right side of the following equation (eq5) is represented by the following equation (eq6).

第２トルク推定部３３ｄは、第２の２次磁束φ８ｒと、各相電流Ｉａｒ〜Ｉｆｒとに基づいて、８極に対応するモータ１０のトルクである第２実トルクＴ８ｒを推定する。

The second torque estimating unit 33d estimates the second actual torque T8r that is the torque of the motor 10 corresponding to the eight poles, based on the second secondary magnetic flux φ8r and the phase currents Iar to Ifr.

  The second torque control unit 33e uses the second q-axis command current Iq8 on the q-axis as an operation amount for feedback-controlling the second actual torque T8r estimated by the second torque estimation unit 33d to the second command torque T8 *. * Is calculated. Note that the feedback control used in the second torque control unit 33e may be proportional integral control, for example.

  The second magnetic flux control unit 33f uses the second d on the d axis as an operation amount for performing feedback control of the second secondary magnetic flux φ8r estimated by the second magnetic flux estimation unit 33b to the second command secondary magnetic flux φ8 *. An axis command current Id8 * is calculated. Note that the feedback control used in the second magnetic flux control unit 33f may be proportional integral control, for example.

  The second current control unit 33g is an operation amount for performing feedback control of the second d-axis current Id8r converted by the second dq conversion unit 33c to the second d-axis command current Id8 * calculated by the second torque control unit 33e. The second d-axis command voltage Vd8 * on the d-axis is calculated. The second current control unit 33g performs an operation for feedback control of the second q-axis current Iq8r converted by the second dq conversion unit 33c to the second q-axis command current Iq8 * calculated by the second torque control unit 33e. As a quantity, the second q-axis command voltage Vq8 * on the q-axis is calculated. Note that the feedback control used in the second current control unit 33g may be proportional integral control, for example.

  The coordinate conversion unit 34 includes the first d and q command voltages Vd4 * and Vq4 * calculated by the first current control unit 32g, the first electrical angle θ4, and the second d and q commands calculated by the second current control unit 33g. Based on the voltages Vd8 *, Vq8 * and the second electrical angle θ8, the A, B, C, D, E, and F phase command voltages Va *, Vb *, Vc *, Vd * in the six-phase fixed coordinate system. , Ve *, Vf * are calculated. Note that the conversion in the coordinate conversion unit 34 may be performed based on, for example, a matrix represented by the following expression (eq7). Here, the transposed matrix of the transformation matrix D shown in the above equation (eq6) is included on the right side of the following equation (eq7). This transpose matrix is expressed by the following equation (eq8).

モータ１０の極数として４極が選択されている場合、座標変換部３４により算出される各相指令電圧Ｖａ＊〜Ｖｆ＊は、下式（ｅｑ９）に示すように、Ａ，Ｂ，Ｃ，Ｄ，Ｅ，Ｆ相の順で６０度ずつずれた波形となる。なお下式（ｅｑ９）において、Ｖｍ４は指令電圧の振幅を示し、ｔは時間を示し、ω４ｃは１次角周波数を示し、σ４は指令電圧の位相を示す。

When four poles are selected as the number of poles of the motor 10, the phase command voltages Va * to Vf * calculated by the coordinate conversion unit 34 are represented by A, B, C, The waveforms are shifted by 60 degrees in the order of D, E, and F phases. In the following equation (eq9), Vm4 represents the amplitude of the command voltage, t represents time, ω4c represents the primary angular frequency, and σ4 represents the phase of the command voltage.

一方、モータ１０の極数として８極が選択されている場合、座標変換部３４により算出される各相指令電圧Ｖａ＊〜Ｖｆ＊は、下式（ｅｑ１０）に示すように、Ａ，Ｂ，Ｃ，Ｄ，Ｅ，Ｆ相の順で１２０度ずつずれた波形となる。なお下式（ｅｑ１０）において、Ｖｍ８は指令電圧の振幅を示し、ω８ｃは１次角周波数を示し、σ８は指令電圧の位相を示す。

On the other hand, when eight poles are selected as the number of poles of the motor 10, the phase command voltages Va * to Vf * calculated by the coordinate conversion unit 34 are represented by A, B, The waveforms are shifted by 120 degrees in the order of C, D, E, and F phases. In the following equation (eq10), Vm8 represents the amplitude of the command voltage, ω8c represents the primary angular frequency, and σ8 represents the phase of the command voltage.

指令値算出部３１は、モータ１０の機械角周波数ωｒが閾値速度以下であると判定した場合にモータ１０の極数として８極を選択し、機械角周波数ωｒが閾値速度を超えると判定した場合にモータ１０の極数として４極を選択する。このため、座標変換部３４により算出される各指令電圧において、４極に対応する１次角周波数ω４ｃは、８極に対応する１次角周波数ω８ｃよりも低い値とされる。具体的には例えば、４極に対応する１次角周波数ω４ｃは、８極に対応する１次角周波数ω８ｃの約１／２倍の値とされる。

When the command value calculation unit 31 determines that the mechanical angular frequency ωr of the motor 10 is equal to or less than the threshold speed, the command value calculation unit 31 selects eight poles as the number of poles of the motor 10 and determines that the mechanical angular frequency ωr exceeds the threshold speed 4 is selected as the number of poles of the motor 10. For this reason, in each command voltage calculated by the coordinate conversion unit 34, the primary angular frequency ω4c corresponding to the four poles is set to a value lower than the primary angular frequency ω8c corresponding to the eight poles. Specifically, for example, the primary angular frequency ω4c corresponding to the 4-pole is set to a value that is about ½ times the primary angular frequency ω8c corresponding to the 8-pole.

  The operation signal generator 35 applies voltages applied to the phase windings 12A, 12B, 12C, 12D, 12E, and 12F from the inverter 20 to the phase command voltages Va *, Vb *, Vc *, Vd *, Ve *, and Vf. An operation signal for setting * is generated, and the generated operation signal is output to each switch of the inverter 20. For example, the operation signal generation unit 35 may generate an operation signal by PWM control based on a magnitude comparison between each phase command voltage and a carrier signal such as a triangular wave signal. Incidentally, in this embodiment, the 4-pole control unit 32, the 8-pole control unit 33, the coordinate conversion unit 34, and the operation signal generation unit 35 correspond to an “inverter operation unit”.

  When four poles are selected as the number of poles of the motor 10 by the control described above, the phase currents Ia4, Ib4 shown in the following equation (eq11) are applied to the phase windings 12A, 12B, 12C, 12D, 12E, 12F. Ic4, Id4, Ie4, If4 flows. In the following equation (eq11), Im4 represents the amplitude of the phase current, and α4 represents the phase of the phase current.

一方、モータ１０の極数として８極が選択された場合、各相巻線１２Ａ，１２Ｂ，１２Ｃ，１２Ｄ，１２Ｅ，１２Ｆに下式（ｅｑ１２）に示す各相電流Ｉａ８，Ｉｂ８，Ｉｃ８，Ｉｄ８，Ｉｅ８，Ｉｆ８が流れる。下式（ｅｑ１２）において、Ｉｍ８は相電流の振幅を示し、α８は相電流の位相を示す。

On the other hand, when eight poles are selected as the number of poles of the motor 10, each phase current Ia8, Ib8, Ic8, Id8, shown in the following equation (eq12) is applied to each phase winding 12A, 12B, 12C, 12D, 12E, 12F. Ie8 and If8 flow. In the following equation (eq12), Im8 represents the amplitude of the phase current, and α8 represents the phase of the phase current.

指令値算出部３１は、極数切替期間において、４極及び８極のうち一方から他方にモータ１０の極数を切り替えるための処理を行う。本実施形態において、指令値算出部３１が「切替部」に相当する。以下、図４を用いて、８極から４極に切り替える場合を例にして説明する。このため本実施形態では、８極が「切替前極数」に相当し、４極が「切替後極数」に相当し、第２指令トルクＴ８＊が「切替前指令トルク」に相当し、第１指令トルクＴ４＊が「切替後指令トルク」に相当する。また、第２指令２次磁束φ８＊が「切替前２次磁束」に相当し、第２ｄ軸指令電流Ｉｄ８＊が「切替前励磁電流」に相当し、第１指令２次磁束φ４＊が「切替後２次磁束」に相当し、第１ｄ軸指令電流Ｉｄ４＊が「切替後励磁電流」に相当する。なお図４（ａ）には、合計指令トルクＴｒ＊が一定とされている例を示す。

The command value calculation unit 31 performs processing for switching the number of poles of the motor 10 from one of the four poles and the eight poles to the other in the pole number switching period. In the present embodiment, the command value calculation unit 31 corresponds to a “switching unit”. Hereinafter, the case of switching from 8 poles to 4 poles will be described as an example with reference to FIG. For this reason, in this embodiment, 8 poles corresponds to the “number of poles before switching”, 4 poles corresponds to the “number of poles after switching”, the second command torque T8 * corresponds to “the command torque before switching”, The first command torque T4 * corresponds to “command torque after switching”. The second command secondary magnetic flux φ8 * corresponds to “secondary magnetic flux before switching”, the second d-axis command current Id8 * corresponds to “excitation current before switching”, and the first command secondary magnetic flux φ4 * is “ This corresponds to the “secondary magnetic flux after switching”, and the first d-axis command current Id4 * corresponds to “excitation current after switching”. FIG. 4A shows an example in which the total command torque Tr * is constant.

  As shown in FIG. 4A, the command value calculation unit 31 determines that the total value of the first command torque T4 * and the second command torque T8 * is the total command torque during the pole number switching period TC from time t2 to t3. The command torques T4 * and T8 * are calculated so as to be Tr *. Thereby, it is possible to suppress the torque of the motor 10 from deviating from the total command torque Tr * in the pole number switching period TC.

  The command value calculation unit 31 starts to decrease the second command torque T8 * from the total command torque Tr * toward 0 at the start timing t2 of the pole number switching period TC, and totals the first command torque T4 * from 0. It starts to increase toward the command torque Tr *. The command value calculation unit 31 gradually decreases the second command torque T8 * and gradually increases the first command torque T4 * in the pole number switching period TC. As a result, it is possible to suppress fluctuations in the phase current and phase voltage due to the decrease in the d-axis current, and to reduce the change rate of the secondary magnetic flux. As a result, the fluctuation of the q-axis current can be suppressed and the torque fluctuation of the motor 10 can be suppressed.

  The command value calculation unit 31 sets the second command torque T8 * to the total command torque Tr * and the first command torque T4 * to the total command torque Tr * at the end timing t3 of the pole number switching period TC.

  The phase command voltages Va * to Vf * in the pole number switching period TC are expressed by the following equation (eq13). Further, the currents Ias, Ibs, Ics, Ids, Ies, Ifs flowing in the A, B, C, D, E, and F phases in the pole number switching period TC are expressed by the following equation (eq14).

指令値算出部３１は、極数切替期間ＴＣにおいて相電圧及び相電流のピーク値の上昇を防止するために、図４（ｃ）に示すように、極数切替期間ＴＣの開始タイミングｔ２に先立つ時刻ｔ１において、第１指令２次磁束φ４＊を０から増加させ始める。指令値算出部３１は、第１指令２次磁束φ４＊を徐々に増加させる。これにより、第１ｄ軸指令電流Ｉｄ４＊が徐々に増加し、図４（ｂ）に示すように第１ｄ軸電流Ｉｄ４ｒも徐々に増加する。

The command value calculation unit 31 precedes the start timing t2 of the pole number switching period TC as shown in FIG. 4C in order to prevent the peak values of the phase voltage and phase current from increasing in the pole number switching period TC. At time t1, the first command secondary magnetic flux φ4 * starts to increase from zero. The command value calculation unit 31 gradually increases the first command secondary magnetic flux φ4 *. As a result, the first d-axis command current Id4 * gradually increases, and the first d-axis current Id4r also gradually increases as shown in FIG. 4B.

  In the present embodiment, the command value calculation unit 31 uses the first command secondary magnetic flux φ4 * and the first d in response to the time constant τ4 of the primary delay element in the motor 10 corresponding to the four poles that are the number of poles after switching. The axis command current Id4 * is gradually increased. As a result, the first secondary magnetic flux φ4r having low responsiveness can be appropriately raised by the time t2 when the first command torque T4 * starts to increase. Further, by gradually increasing the first d-axis command current Id4 *, the first d-axis current Id4r can be gradually increased, and the increase in the phase voltage and phase current due to the change in the first d-axis current Id4r is suppressed. it can. The time constant τ4 is determined by the characteristics of the rotor of the motor 10. The characteristics of the rotor include, for example, the winding resistance value of the rotor and the self-inductance of the rotor. FIG. 5 shows a time constant τ4 with respect to the step response of the first d-axis command current Id4 * at times t1 to t2.

  In order to prevent the peak value of the phase voltage and phase current from increasing in the pole number switching period TC, the command value calculation unit 31 performs the second command secondary magnetic flux φ8 at time t1, as shown in FIG. * Decrease toward 0. The command value calculation unit 31 gradually decreases the second command secondary magnetic flux φ8 *. As a result, the second d-axis command current Id8 * gradually decreases toward 0, and the second d-axis current Id8r also decreases gradually toward 0 as shown in FIG. 4 (e).

  In the present embodiment, the command value calculation unit 31 has the same responsiveness as the time constant τ8 of the primary delay element in the motor 10 corresponding to the 8-pole number before switching, and the second command secondary magnetic flux φ8 * and The second d-axis command current Id8 * is gradually decreased. Thus, the second secondary magnetic flux φ8r can be appropriately lowered by time t2 when the second command torque T8 * starts to decrease. Further, by gradually reducing the second d-axis command current Id8 *, the second secondary magnetic flux φ8r can be gradually reduced, and the fluctuation of the second q-axis current Iq8r can be suppressed. The time constant τ8 is determined by the characteristics of the rotor of the motor 10. FIG. 6 shows the time constant τ8 for the step response of the second d-axis command current Id8 * at times t1 to t2.

  In FIG. 4, the time from t1 to t2 is set to the time constant τ4 corresponding to the four poles that are the number of poles after switching. Thereby, the reduction effect of the phase voltage and phase current in pole number switching period TC can be heightened.

  The command value calculation unit 31 increases the second q-axis command current Iq8 * corresponding to the number of poles before switching from the second q-axis command current Iq8 * calculated by the second torque control unit 33e at time t1 to t2. Let As a result, it is possible to compensate for the torque decrease associated with the decrease in the second secondary magnetic flux φ8r from time t1. In addition, since the decrease change of the second secondary magnetic flux φ8r is delayed with respect to the decrease change of the second d-axis current Id8r, the increase amount of the second q-axis current Iq8r with respect to the decrease amount of the second d-axis current Id8r. Is small. For this reason, even if the second q-axis current Iq8r is increased, the peak values of the phase current and the phase voltage do not vary greatly.

  The above-described processing of the command value calculation unit 31 when switching from 8 poles to 4 poles can be similarly applied when switching from 4 poles to 8 poles. In this case, the command value calculation unit 31 changes the first q-axis command current Iq4 * corresponding to the number of poles before switching to the first q-axis command current Iq4 * calculated by the first torque control unit 32e at time t1 to t2. In contrast, it may be increased.

  Subsequently, a comparison technique for comparison with the present embodiment will be described with reference to FIG. FIG. 7 shows a case where switching from 8 poles to 4 poles is performed. In the comparative technique shown in FIG. 7, in order to start up the first secondary magnetic flux φ4r shown in FIG. 7C at the start timing t1 of the pole number switching period TC, the first d as shown in FIG. The shaft current Id4r is raised stepwise. Then, the first q-axis current Iq4r is gradually increased so that the torque of the motor 10 corresponding to the four poles follows the first command torque T4 *. Here, in the comparative technique, since the first d-axis voltage rises steeply in order to raise the first d-axis current Id4r stepwise, the peak of the phase voltage generated in the motor 10 as shown in FIG. The value becomes larger than the peak value of the phase voltage shown in FIG.

  Further, since the first d-axis current Id4r rises in a step shape, the peak value of the phase current is larger in the comparative technique than in the present embodiment as shown in FIG. FIG. 8 shows the simulation results of the comparative technique and this embodiment when switching from 8 poles to 4 poles. Trr in the column showing the torque waveform in FIG. 8 indicates the actual torque of the motor 10. 8 corresponds to the time t1 in FIG. 7, and t1 and t2 in the present embodiment in FIG. 8 correspond to the times t1 and t2 in FIG. .

  As shown in FIG. 8, according to the present embodiment, the increase in the first d-axis current Id4r can be moderated and the peak values of the phase current and the phase voltage can be reduced as compared with the comparative technique.

  Incidentally, in the present embodiment, the system includes a display unit 50 as shown in FIG. The display unit 50 is a display of a navigation device, for example. The control device 30 performs a process of displaying on the display unit 50 that the current time is within the pole number switching period. Thereby, the user of the vehicle can grasp that the number of poles of the motor 10 is being switched. Moreover, the control apparatus 30 performs the process which displays on the display part whether the present pole number of the motor 10 is 4 poles or 8 poles. Thereby, the user can grasp | ascertain the present pole number of the motor 10. FIG.

  In the present embodiment described above, the post-switching excitation current is increased prior to the start timing of the pole number switching period TC. This eliminates the need to rapidly increase the d-axis current corresponding to the number of poles after switching. As a result, the peak value of the phase voltage and phase current generated in the motor 10 can be reduced. Prior to the start timing of the pole number switching period TC, the excitation current before switching is reduced. Thereby, the peak value of a phase voltage and a phase current can be lowered by the start timing of the pole number switching period TC. As a result, the peak values of the phase voltage and phase current generated in the motor 10 in the pole number switching period TC can be reduced.

  According to the present embodiment, the number of poles can be switched regardless of the load state of the motor 10. For this reason, even when the load state of the motor 10 is a high load state, the number of poles can be switched without reducing the total command torque Tr *.

(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, as shown in FIG. 9, the torque control method of the control device 30 is changed to a method using a slip angular frequency. In FIG. 9, the same components as those shown in FIG. 3 are given the same reference numerals for the sake of convenience.

  The control device 30 includes a command value calculation unit 36. The command value calculation unit 36, based on the acquired total command torque Tr * and the mechanical angular frequency ωr, the first d-axis command current Id4 *, the first q-axis command current Iq4 *, the second d-axis command current Id8 *, the first A first slip angular frequency ωs4 that is a slip angular frequency corresponding to 2q-axis command current Iq8 * and 4 poles, and a second slip angular frequency ωs8 that is a slip angular frequency corresponding to 8 poles are calculated. The command value calculation unit 36 includes the torque of the motor 10 corresponding to four poles determined from the first d-axis command current Id4 * and the first q-axis command current Iq4 *, the second d-axis command current Id8 *, and the second q-axis command current Iq8 *. The first d-axis command current Id4 *, the first q-axis command current Iq4 *, the second d-axis command current Id8 *, and the added value with the torque of the motor 10 corresponding to the eight poles determined from The second q-axis command current Iq8 * is calculated.

  The 4-pole control unit 32 will be described. The first adder 32h adds the first slip angular frequency ωs4 calculated by the command value calculator 36 to the first electrical angular frequency ω4r calculated by the first frequency calculator 32a, and outputs the result.

  The first angle calculator 32i calculates the first electrical angle θ4 by integrating the output value of the first adder 32h. The calculated first electrical angle θ4 is input to the first dq converter 32c and the coordinate converter 34.

  The 8-pole control unit 33 will be described. The second adder 33h adds the second slip angular frequency ωs8 calculated by the command value calculator 36 to the second electrical angular frequency ω8r calculated by the second frequency calculator 33a, and outputs the result.

  The second angle calculation unit 33i calculates the second electrical angle θ8 by integrating the output value of the second addition unit 33h. The calculated second electrical angle θ8 is input to the second dq converter 33c and the coordinate converter 34.

  Next, the processing at the time of switching the number of poles according to the present embodiment will be described by taking the case of switching from 8 poles to 4 poles as an example.

  In the present embodiment, the command value calculation unit 36 starts increasing the first d-axis command current Id4 * from 0 instead of the first command secondary magnetic flux φ4 * prior to the start timing of the pole number switching period TC. The command value calculation unit 36 gradually increases the first d-axis command current Id4 *.

  Prior to the start timing of the pole number switching period TC, the command value calculation unit 36 starts to decrease the second d-axis command current Id8 * toward 0 instead of the second command secondary magnetic flux φ8 *. The command value calculation unit 36 gradually decreases the second d-axis command current Id8 *.

  According to the present embodiment described above, it is possible to obtain the same effect as that of the first embodiment.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment. In the present embodiment, as shown in FIG. 10, the system includes two three-phase inverters 26A and 26B corresponding to the number of winding groups. In FIG. 10, the same or corresponding components as those shown in FIG. 1 are given the same reference numerals for the sake of convenience. In FIG. 10, the display unit 50 is not shown.

  The first inverter 26A includes an A phase upper and lower arm switches SAp and SAn, a B phase upper and lower arm switches SBp and SBn, and a C phase upper and lower arm switches SCp and SCn. The second inverter 26B includes D-phase upper and lower arm switches SDp and SDn, E-phase upper and lower arm switches SEp and SEn, and F-phase upper and lower arm switches SFp and SFn.

  According to the present embodiment described above, it is possible to obtain the same effect as that of the first embodiment.

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

  Prior to the start timing of the pole number switching period, only one of the process of increasing the excitation current after switching and the process of decreasing the excitation current before switching may be performed. Even in this case, it is possible to obtain the effects according to the effects of the above embodiments.

  The method for gradually increasing and decreasing the excitation current is not limited to the method shown by the solid line in FIG. For example, it may be changed as shown by a one-dot chain line in FIG. 11, or may be changed into a ramp shape as shown by a broken line in FIG. FIG. 11 illustrates the case where the first d-axis command current Id4 * is increased.

  Further, the method of gradually changing the excitation current is not limited to the method of changing continuously as shown in FIG. 11, and may be a method of changing stepwise.

  -Prior to the start timing of the pole number switching period, the method of changing the excitation current after switching is not limited to the method of gradually changing, and may be a method of changing in a stepped manner.

  -A motor having four or more phases may be used. Further, three or more sets of stator windings may be provided on the stator. In this case, the number of phases of the inverter may be “number of sets of stator windings n” × “number of phases of motor m”. The inverter includes a set of upper and lower arm switches corresponding to the number of phases.

  When A is an even number of 2 or more, the number of poles that can be switched between the motors may be a pair of A poles and “n × A” poles. For this reason, the number of poles is not limited to a group of 4 and 8 poles. For example, when n = 2, a group of 2 and 4 poles, or a group of 8 and 16 poles may be used. .

  -The number of poles to which the motor can be switched is not limited to two and may be three or more. For example, in the case of a motor that can be switched to any of 4 poles, 8 poles, and 16 poles, when switching from one of the 4 poles and 8 poles to the other, and from one to the other of the 8 poles and 16 poles In some cases, a process for increasing the post-switching excitation current and a process for decreasing the pre-switching excitation current can be applied prior to the start timing of the pole number switching period.

  The motor is not limited to the one used as the in-vehicle main machine, but may be used as, for example, the in-vehicle auxiliary machine. Further, the system provided with the motor and the inverter is not limited to the one mounted on the vehicle.

  DESCRIPTION OF SYMBOLS 10 ... Motor, 20 ... Inverter, 30 ... Control apparatus.

Claims (10)

Applied to a system comprising an electric motor (10) capable of switching the number of poles, and an inverter (20; 26A, 26B) electrically connected to the electric motor,
In the case where m is an integer of 3 or more and n is an integer of 2 or more, the electric motor has n sets of m-phase stator windings (12A to 12F),
In the case where A is an even number of 2 or more, one of the A pole and the n × A pole is defined as the number of poles before switching, and the other is defined as the number of poles after switching,
The pre-switching torque, which is the torque of the motor corresponding to the pre-switching pole number, is controlled to the pre-switching command torque, and the post-switching torque, which is the torque of the motor corresponding to the post-switching pole number, is An inverter operation unit (32 to 35) for operating the inverter to control the torque;
A switching unit (31; 36) for gradually decreasing the pre-switching command torque toward 0 and gradually increasing the post-switching command torque toward a value larger than 0 in the pole number switching period; With
A secondary magnetic flux of the motor corresponding to the number of poles before switching is defined as a secondary magnetic flux before switching, and a current flowing through the motor to generate the secondary magnetic flux before switching is defined as an excitation current before switching, The secondary magnetic flux of the electric motor corresponding to the number of poles after switching is defined as secondary magnetic flux after switching, and the current flowing through the motor to generate the secondary magnetic flux after switching is defined as post-switching excitation current,
Prior to the start timing of the pole number switching period, the switching unit controls the pole number switching motor that performs at least one of a process of increasing the post-switching excitation current and a process of decreasing the pre-switching excitation current. apparatus.   2. The control apparatus for a pole number switching motor according to claim 1, wherein the switching unit performs a process of increasing a secondary magnetic flux after the switching before the start timing of the pole number switching period.   3. The control device for a pole number switching motor according to claim 2, wherein the switching unit performs a process of gradually increasing the secondary magnetic flux after the switching before the start timing of the pole number switching period.   The pole switching motor according to claim 3, wherein the switching unit performs a process of gradually increasing the secondary magnetic flux after switching with a response equivalent to a secondary time constant in the motor corresponding to the number of poles after switching. Control device.   The control device for a pole number switching motor according to any one of claims 1 to 4, wherein the switching unit performs a process of reducing the secondary magnetic flux before switching before the start timing of the pole number switching period.   6. The control device for a pole number switching motor according to claim 5, wherein the switching unit performs a process of gradually reducing the secondary magnetic flux before switching before the start timing of the pole number switching period.   The pole number switching motor according to claim 6, wherein the switching unit performs a process of gradually decreasing the secondary magnetic flux before switching with a response equivalent to a secondary time constant in the motor corresponding to the number of poles before switching. Control device.   The switching unit performs a process of decreasing a secondary magnetic flux before switching and increasing a torque current flowing through the motor corresponding to the pre-switching command torque prior to a start timing of the pole number switching period. The control apparatus of the pole number switching motor of any one of -7. The switching unit acquires a total command torque of the electric motor, and the switching is performed so that a total value of the pre-switching command torque and the post-switching command torque becomes the acquired total command torque in the pole number switching period. Set the pre-command torque and the post-switch command torque,
The switching unit gradually decreases the pre-switching command torque from the total command torque toward 0 and the post-switching command torque from 0 toward the total command torque during the pole number switching period. The control device for a pole number switching motor according to any one of claims 1 to 8, which is gradually increased.   The switching unit is configured to increase the post-switching excitation current at a timing prior to the pole number switching period by a secondary time constant of the motor corresponding to the post-switching pole number, and before the switching The control device for a pole number switching motor according to any one of claims 1 to 9, wherein at least one of the processes for reducing the excitation current is started.

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