Control method for an open-wound motor, and control system for an open-wound motor

Abstract

By devising an AC voltage command method, this invention provides a control method and control system for an open-wound motor that can drive two multi-phase motors while sharing switching elements. [Solution] The system includes an open-winding first motor 1 and a second motor 2, a first inverter 3 connected to one end of the winding of the first motor 1, a second inverter 4 connected to one end of the winding of the second motor 2, and a third inverter 5 connected in parallel to the other end of the winding of the first motor 1 and the other end of the winding of the second motor 2. The first to third inverters are controlled so that the sum of the first AC current output from the first inverter 3 and the second AC current output from the second inverter 4 becomes the third AC current input to the third inverter 5, thereby generating a phase difference between the first AC current and the second AC current.

Description

[Technical Field]

[0001] The present invention relates to a control method for an open-wound motor and a control system for an open-wound motor. [Background technology]

[0002] Patent Document 1 discloses a technology for reducing the number of elements by sharing switching elements for driving multiphase motors and DC motors. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-28472 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, Patent Document 1 does not describe a configuration for driving two multiphase motors, nor does it mention an AC voltage command method that addresses the region where the degree of freedom of voltage is reduced by sharing switching elements, making it impossible to apply the AC voltage as commanded.

[0005] The present invention aims to provide a control method for an open-wound motor and a control system for an open-wound motor that can drive two multi-phase motors while sharing switching elements by devising an AC voltage command method. [Means for solving the problem]

[0006] The control method for an open-winding motor according to the present invention includes a first motor and a second motor, both open-winding motors having multiple independent phase windings as stators; a first inverter connected to one end of the winding of the first motor; a second inverter connected to one end of the winding of the second motor; and a third inverter connected in parallel to the other end of the winding of the first motor and the other end of the winding of the second motor. The control method controls the first inverter, the second inverter, and the third inverter so that the sum of the first AC current output from the first inverter and the second AC current output from the second inverter becomes the third AC current input to the third inverter. In this control method, a phase difference is generated between the first AC current and the second AC current. [Effects of the Invention]

[0007] According to the present invention, by sharing the switching elements that constitute the inverter, it becomes possible to issue AC voltage commands corresponding to regions where the AC voltage cannot be applied as commanded due to a reduction in the degree of freedom of voltage, and furthermore, by generating a phase difference between the first AC current and the second AC current, the conduction loss of the switching elements can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows the first basic configuration of a motor drive device to which the control system for the open-wound motor of the first embodiment is applied. [Figure 2] Figure 2 shows a second basic configuration of a motor drive device to which the control system for the open-wound motor of the first embodiment is applied. [Figure 3] Figure 3 shows the relationship between the phase difference of the alternating current, the output of the first and second motors, and the maximum current of the third inverter. [Figure 4] Figure 4 shows the control configuration of the control system for an open-wound motor according to the first embodiment. [Figure 5]Figure 5 shows the control configuration of the PWM conversion unit that constitutes the control system of the open-wound motor according to the first embodiment. [Figure 6] Figure 6 shows the control configuration of the control system for an open-wound motor according to the second embodiment. [Figure 7] Figure 7 is a vector diagram for calculating the voltage command value of the first inverter, the voltage command value of the second inverter, and the voltage command value of the third inverter in the first U-phase inverter voltage calculation unit that constitutes the control system of the open-wound motor of the second embodiment. [Figure 8] Figure 8 is a vector diagram for calculating the voltage command value of the first inverter, the voltage command value of the second inverter, and the voltage command value of the third inverter in the second U-phase inverter voltage calculation unit that constitutes the control system of the open-wound motor of the second embodiment. [Figure 9] Figure 9 shows the control configuration of the control system for an open-wound motor according to the third embodiment. [Figure 10] Figure 10 shows the configuration in which the PWM conversion unit shown in Figure 9 calculates the correction coefficient. [Figure 11] Figure 11 shows the relationship between the phase difference between the AC voltage of the winding of the first motor and the AC voltage of the winding of the second motor, and the usable voltage of the first and second motors. [Figure 12] Figure 12 shows an example of inverter conduction loss in a control system for an open-wound motor of a comparative example. [Figure 13] Figure 13 shows a first example of the conduction loss of the inverter in the control system of an open-wound motor according to this embodiment. [Figure 14] Figure 14 shows a second example of the conduction loss of the inverter in the control system of the open-wound motor of this embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the attached drawings.

[0010] [Motor drive device] Figure 1 shows the first basic configuration of a motor drive device to which the control system for an open-wound motor of the first embodiment is applied. Figure 2 shows the second basic configuration of a motor drive device to which the control system for an open-wound motor of the first embodiment is applied.

[0011] The motor drive system includes an open-winding first motor 1 and a second motor 2, a first inverter 3, a second inverter 4, a third inverter 5, and a DC power supply 6. In the first basic configuration shown in Figure 1, the DC power supply 6 is independently attached to each inverter, while in the second basic configuration shown in Figure 2, all inverters are connected in parallel to a single DC power supply 6. The motor drive system is installed, for example, in an electric vehicle (or hybrid vehicle), where the first motor 1 drives the front wheels and the second motor 2 drives the rear wheels. In another embodiment, the first motor 1 drives the left front wheel (or left rear wheel) and the second motor 2 drives the right front wheel (or right rear wheel).

[0012] The first motor 1 and the second motor 2 are equipped with stator windings that allow for independent control of the voltage applied to the windings of each of the three or more phases.

[0013] One end of the winding of the first motor 1 is connected to the first inverter 3, and one end of the winding of the second motor 2 is connected to the second inverter 4. The other end of the winding of the first motor 1 and the other end of the winding of the second motor 2 are connected in parallel to the third inverter 5.

[0014] The motor drive device generates a phase difference between the first AC current flowing through the winding of the first motor 1 and the second AC current flowing through the winding of the second motor 2. However, it is not always necessary to generate a phase difference; they may be in phase. Also, even when a phase difference is generated, one AC current will have a leading phase and the other a lagging phase, but this can be reversed.

[0015] The first inverter 3, the second inverter 4, and the third inverter 5 are power conversion circuits that convert DC power supplied from a DC power source 6 into AC power. They are composed of switching elements typified by IGBTs and MOSFETs, and for example, include half-bridge circuits corresponding to the number of phases.

[0016] When driving the first motor 1 and the second motor 2 without restriction on the phase difference between the first AC current and the second AC current, the maximum value of the current flowing through the third inverter 5 is the sum of the maximum value of the current flowing through the first inverter 3 and the maximum value of the current flowing through the second inverter 4. Therefore, the current capacity of the third inverter 5 is the sum of the current capacity of the first inverter 3 and the current capacity of the second inverter 4 (see FIG. 13).

[0017] The voltage applied to the first motor 1 is the difference between the voltage output by the first inverter 3 and the voltage output by the third inverter 5. The voltage applied to the second motor 2 is the difference between the voltage output by the second inverter 4 and the voltage output by the third inverter 5.

[0018] The DC power source 6 is a device that supplies DC power including, for example, a laminated lithium-ion battery.

[0019] With the above configuration, the open-wound first motor 1 and second motor 2 can be controlled by the first inverter 3, the second inverter 4, and the third inverter 5.

[0020] [Phase Difference of AC Current and Outputs of First Motor 1 and Second Motor 2] FIG. 3 is a diagram showing the relationship between the phase difference (β diff ) of the AC current, the outputs of the first motor 1 and the second motor 2, and the maximum current of the third inverter 5.

[0021] A motor control controller 23 (FIG. 4), which will be described later, sets the maximum current (I max1 ) flowing through the first motor 1 and the maximum output requirement according to the system's requirements. Similarly, the motor control controller 23 (FIG. 4) sets the maximum current (I max2) and set the maximum output requirement.

[0022] In this embodiment, since the third inverter 5 is commonly used when supplying power to the first motor 1 and the second motor 2, the phase difference (β diff ) between the first alternating current and the second alternating current causes the maximum output that can be applied to each of the first motor 1 and the second motor 2 to change.

[0023] Therefore, as shown in FIG. 3, the phase difference (β diff ) between the first alternating current and the second alternating current, and the magnitudes of the currents flowing through the first motor 1 and the second motor 2 respectively cause the maximum outputs of the first motor 1 and the second motor 2 to change respectively.

[0024] The characteristic curves representing the maximum outputs of the first motor 1 and the second motor 2 shown in FIG. 3 monotonically decrease as the phase difference increases, but monotonically increase as the maximum current increases.

[0025] The characteristic curve representing the maximum current of the third inverter 5 shown in FIG. 3 monotonically decreases as the phase difference (β diff ) increases, but monotonically increases as the ratio between the maximum current (I max1 ) of the first motor 1 and the maximum current (I max2 ) of the second motor 2 increases. When the ratio is 1:1 and the phase difference is 180 [deg], the maximum current of the third inverter 5 becomes zero, and the third inverter 5 can stop operating.

[0026] As shown in FIG. 3, for example, set the maximum current (I max1 ) flowing through the first motor 1 to 1 [p.u.] (arbitrary unit, the same hereinafter), and set the maximum current (I max2 ) flowing through the second motor 2 to 4 [p.u.].

[0027] When the maximum output (the maximum output that can be instantaneously output) requirement of the first motor 1 is set to, for example, 1.5 [p.u.], point A is set as the operating point on the characteristic curve representing the maximum output. At this time, the phase difference (β diff ) is approximately 98 [deg].

[0028] When the maximum output requirement of the second motor 2 is set to, for example, 5.6 [pu], B is set as the operating point on the characteristic curve representing that maximum output, and at this time the phase difference (β) diff ) is approximately 90 degrees.

[0029] The motor control controller 23 (Figure 4), described later, simultaneously fulfills the maximum output requirements of the first motor 1 and the second motor 2 by using the two phase differences (β) diff The smaller of these values ​​(phase difference of operating point B (approximately 90 [deg])) is the phase difference (β diff The lower limit (β) diff_min Set to ). Therefore, the maximum current and phase difference (β) of the third inverter 5 shown in Figure 3 are set to ). diff C is set as the operating point in the characteristic curve (Imax1:Imax2=1:4) that represents the relationship with ).

[0030] At this time, the maximum current (I) flowing through the third inverter 5 max3 ) is the maximum current (I) set for the first motor 1. max1 ), the maximum current set for the second motor 2 (I max2 ), phase difference (β diff The lower limit (β) diff_min It is determined by (3) as shown.

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[0031] When the continuous rated output requirement for the first motor 1 (an output lower than the maximum output mentioned above, but a rated output that can be output steadily) is set to, for example, 1.1[pu], D is set as the operating point on the characteristic curve representing the continuous rated output, and at this time the phase difference (β) diff ) is approximately 150 [deg].

[0032] When the continuous rating requirement for the second motor 2 is set to, for example, 4.1[pu], E is set as the operating point on the characteristic curve representing the rated output, and at this time the phase difference (β) diff ) is approximately 158 degrees.

[0033] The motor control controller 23 (Figure 4), described later, simultaneously fulfills the continuous rated output requirements of the first motor 1 and the second motor 2 by setting the smaller of the two phase differences (phase difference at operating point D (approximately 150 [deg])) to the maximum value of the phase difference (β diff_max Set to ). Therefore, the characteristic curve (I) shown in Figure 3 represents the relationship between the maximum current (continuous rated current) and the phase difference of the third inverter 5. max1 :I max2 F is set as the operating point in the ratio (1:4).

[0034] Compared to the conventional configuration in which inverters are individually connected to both ends of each open-winding motor, in this embodiment, the first motor 1 and the second motor 2 are connected in parallel to the third inverter 5. In this embodiment, a phase difference (β) is set between the first AC current flowing through the winding of the first motor 1 and the second AC current flowing through the winding of the second motor 2. diff The conduction loss of the third inverter 5 can be reduced if ) is present. A detailed explanation will be given using Figures 13 and 14 below. In addition, the current capacity of the third inverter 5 can be reduced to the maximum extent while achieving the output required by the system. A detailed explanation will be given using Figure 14 below.

[0035] [Control system of the first embodiment] Figure 4 shows the control configuration of the control system for an open-wound motor according to the first embodiment. In this embodiment, the first motor 1 and the second motor 2 are configured to have three independent windings.

[0036] The control system in this embodiment includes a first motor 1, a second motor 2, a first inverter 3, a second inverter 4, a third inverter 5, a DC power supply 6, a first current detector 18 for detecting the current of the first motor 1, a second current detector 19 for detecting the current of the second motor 2, a first rotor angle detector 20 for detecting the rotor angle of the first motor 1, a second rotor angle detector 21 for detecting the rotor angle of the second motor 2, a voltage detector 22 for detecting the voltage of the DC power supply 6, and a motor control controller 23.

[0037] The motor control controller 23 controls the torques of the first motor 1 and the second motor 2 according to the required torque from a host controller or the like. To do so, based on the rotor angle (θ re1 ) and the phase current (i u1 , i v1 ) of the first motor 1, the rotor angle (θ re2 ) and the phase current (i u2 , i v2 ) of the second motor 2, and the voltage (V dc ) of the DC power supply 6, it controls the ON / OFF timings of the switching elements of the first inverter 3, the second inverter 4, and the third inverter 5.

[0038] The motor control controller 23 includes a first three-phase AC / d-q coordinate converter 24, a second three-phase AC / d-q coordinate converter 25, an angular velocity calculator 26, a torque command / current command converter 27, a first current control unit 28, a second current control unit 29, a first d-q coordinate / three-phase AC converter 30, a second d-q coordinate / three-phase AC converter 31, and a PWM converter 32.

[0039] The first three-phase AC / d-q coordinate converter 24 calculates first dq-axis currents (i u1 , i v1 ) that are the dq-axis currents of the first motor 1 based on the phase current (i re1 ) detected by the first current detector 18 and the rotor angle (θ d1 ) of the first motor 1 detected by the first rotor angle detector 20.

[0040] The second three-phase AC / d-q coordinate converter 25 calculates second dq-axis currents (i u2 , i v2 ) that are the dq-axis currents of the second motor 2 based on the phase current (i re2 ) detected by the second current detector 19 and the rotor angle (θ d2 ) of the second motor 2 detected by the second rotor angle detector 21.

[0041] The angular velocity calculator 26 calculates the rotor angle (θ​​​re1 Based on this, the rotor angular velocity (ω) of the first motor 1 re1 ) is calculated, and the rotor angle (θ) of the second motor 2 is calculated. re2 Based on this, the rotor angular velocity (ω) of the second motor 2 re2 Calculate ).

[0042] The torque command / current command conversion unit 27 receives the first torque command value (T1) commanded to the first motor 1. * ) and the first torque command value (T1) commanded toward the second motor 2 * ) is entered. First torque command value (T1 * ) and the second torque command value (T2 * The sum of these is the target torque (T * ) However, the first torque command value (T1 * ) and the second torque command value (T2 * The ratio of the size of the motor drive unit is set by a higher-level controller or the like based on the vehicle status or driver request of the electric vehicle (or hybrid vehicle) equipped with the motor drive unit.

[0043] The torque command / current command conversion unit 27 converts the first torque command value (T1 * ), rotor angular velocity of the first motor 1 (ω re1 ), DC voltage (V dc ), the first dq axis current command value (i) output toward the first motor 1 d1 * i q1 * The first map data has a relationship with the second torque command value (T2 * ), the rotor angular velocity of the second motor 2 (ω re2 ), DC voltage (V dc ), the second dq axis current command value (i) output to the second motor 2. d2 * i q2 * It has a second map data that has a relationship with ).

[0044] The torque command / current command conversion unit 27 converts the first torque command value (T1 * ), rotor angular velocity of the first motor 1 (ω re1 ), DC voltage (Vdc ) is input into the first map data to calculate the first dq-axis current command value (i d1 * , i q1 * ).

[0045] The torque command / current command conversion unit 27 inputs the second torque command value (T2 * ), the rotor angular velocity (ω re2 ) of the second motor 2, and the DC voltage (V dc ) into the second map data to calculate the second dq-axis current command value (i d2 * , i q2 * ).

[0046] The first current control unit 28 calculates the first dq-axis voltage command value (v d1 * , i q1 * ), the first dq-axis current (i d1 , i q1 ), and the rotor angular velocity (ω re1 ) of the first motor 1. d1 * , v q1 * ).

[0047] The second current control unit 29 calculates the second dq-axis voltage command value (v d2 * , i q2 * ), the second dq-axis current (i d2 , i q2 ), and the rotor angular velocity (ω re2 ) of the second motor 2. d2 * , v q2 * ).

[0048] The first dq-axis voltage command value (v d1 * , v q1 * ) and the second dq-axis voltage command value (v d2 * , vq2 * The first torque command value (T1) can generally be determined by the sum of voltages calculated by non-interference voltage control, which suppresses interference between the dq axes, and current feedback control, which is represented by PI control and PID control. However, in this embodiment, the first torque command value (T1) * The first dq axis voltage command value (v) follows the ) d1 * , v q1 * ) is calculated, and the second torque command value (T2 * The second dq-axis voltage command value (v) follows the second dq-axis voltage command value (v d2 * , v q2 * The configuration for calculating the torque command / current command is not limited to the torque command / current command conversion unit 27, the first current control unit 28, and the second current control unit 29.

[0049] The first d-q coordinate / three-phase AC converter 30 controls the first dq axis voltage command value (v d1 * , v q1 * Based on this, the first amplitude command value (v) of the three-phase voltage output toward the first motor 1 is determined. u1 * , v v1 * , v w1 * ) and the first phase command value (α u1 * , α v1 * , α w1 * Calculate ).

[0050] The second d-q coordinate / three-phase AC converter 31 controls the second dq axis voltage command value (v d2 * , v q2 * The second amplitude command value (v) of the three-phase voltage output to the second motor 2 is determined based on ). u2 * , v v2 * , v w2 * ) and the second phase command value (α u2 * , αv2 * , α w2 * Calculate ).

[0051] The PWM conversion unit 32 outputs a first amplitude command value (v) of the three-phase voltage toward the first motor 1. u1 * , v v1 * , v w1 * ) and the first phase command value (α u1 * , α v1 * , α w1 * ), the second amplitude command value (v) of the three-phase voltage output toward the second motor 2 u2 * , v v2 * , v w2 * ) and the second phase command value (α u2 * , α v2 * , α w2 * ), rotor angle (θ) of the first motor 1 re1 ), rotor angle (θ) of the second motor 2 re2 A DC voltage (Vdc) is input.

[0052] The PWM conversion unit 32 outputs a first PWM signal (D) to the switching element of the first inverter 3 based on the input information. u1 , D v1 , D w1 ) Duty cycle, second PWM signal (D) output to the switching element of the second inverter 4 u2 , D v2 , D w2 ) Duty cycle, third PWM signal (D) output to the switching element of third inverter 5 u3 , D v3 , D w3 Calculate the duty cycle for each of the following.

[0053] The PWM conversion unit 32 receives a first PWM signal (D) with a set duty cycle. u1 , Dv1 , D w1 The second PWM signal (D) with a set duty cycle is output to the switching element of the first inverter 3. u2 , D v2 , D w2 The ) is output to the switching element of the second inverter 4, and the third PWM signal (D) with the duty cycle set is output. u3 , D v3 , D w3 The signal is output to the switching element of the third inverter 5. A detailed explanation of the PWM conversion unit 32 will be given later.

[0054] [PWM conversion unit 32] Figure 5 shows the control configuration of the PWM conversion unit 32 that constitutes the control system of the open-wound motor according to the first embodiment.

[0055] As shown in Figure 5, the PWM conversion unit 32 includes a U-phase inverter voltage optimization calculation unit 33, an inverter instantaneous voltage 34 calculation unit, and a duty cycle calculation unit 35.

[0056] Here, the U-phase PWM signal (D u1 , D u2 , D u3 The calculation method for the V-phase PWM signal (D) will be explained in detail, but v1 , D v2 , D v3 ) and W-phase PWM signal (D w1 , D w2 , D w3 The same method can be used to calculate the same value.

[0057] The voltage applied to the winding of the first motor 1 is determined by the difference between the voltage output by the first inverter 3 and the voltage output by the third inverter 5, and the voltage applied to the winding of the second motor 2 is determined by the difference between the voltage output by the second inverter 4 and the voltage output by the third inverter 5. There are infinitely many combinations of these voltages if there are no constraints on the voltages of each inverter.

[0058] On the other hand, the maximum voltage that each inverter can output is the connected DC voltage (V dcBecause of the constraints imposed by the following, it is desirable that the motor voltage be applied to each inverter with high utilization efficiency.

[0059] Therefore, in this embodiment, the voltage command value for the first inverter 3 that achieves a high voltage utilization rate for each inverter is (v u_inv1 * , α u_inv1 * ), voltage command value for the second inverter 4 (v u_inv2 * , α u_inv2 * ), voltage command value (v) for the third inverter 5 u_inv3 * , α u_inv3 * Calculate ).

[0060] The U-phase inverter voltage optimization calculation unit 33 receives the amplitude command value (v u1 * , v u2 * ), phase command value (α u1 * , α u2 * ), DC voltage (V dc ), rotor angle (θ) of the first motor 1 re1 ), rotor angle (θ) of the second motor 2 re2 ) is entered.

[0061] The U-phase inverter voltage optimization calculation unit 33 calculates the voltage command value (v) for the first inverter 3 that satisfies equation (4). u_inv1 * , α u_inv1 * ), voltage command value for the second inverter 4 (v u_inv2 * , α u_inv2 * ), voltage command value (v) for the third inverter 5 u_inv3 * , α u_inv3 * The following is calculated and output to the inverter instantaneous voltage calculation unit 34.

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[0062] Here, equation (4) satisfies equations (5)-(10) below.

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[0063] The inverter instantaneous voltage calculation unit 34 calculates the input voltage command value (v) for the first inverter 3. u_inv1 * , α u_inv1 * ), voltage command value for the second inverter 4 (v u_inv2 * , α u_inv2 * ), voltage command value (v) for the third inverter 5 u_inv3 * , α u_inv3 * ), rotor angle (θ) of the first motor 1 re1 ), rotor angle (θ) of the second motor 2 re2 Based on this, the U-phase voltage (v) of each inverter u_inv1 , v u_inv2 , v u_inv3 The result is calculated as shown in equations (11)-(13) and output to the Duty Calculation Unit 35.

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[0064] From equations (4)-(17) above, once the voltages of the first motor 1, the second motor 2, and the third inverter 5 are determined, the voltages of the first inverter 3 and the second inverter 4 are also uniquely determined.

[0065] In this embodiment, the maximum value of each inverter voltage is the DC voltage (V) of the DC power supply 6. dc Because it is constrained by ), the U-phase voltage amplitude of the third inverter 5 (v) such that the voltages of each inverter are equal. u_inv3 * ), phase (α u_inv3 * By calculating this through optimization, the voltage of all inverters can be used with high utilization efficiency.

[0066] The duty cycle calculation unit 35 calculates the U-phase voltage (v) of each inverter. u_inv1 , v u_inv2 , v u_inv3) and DC voltage (V dc ) is entered.

[0067] The duty cycle calculation unit 35 calculates the U-phase voltage (v u_inv1 , v u_inv2 , v u_inv3 ) to DC voltage (V dc By dividing by ), the PWM signal of the U phase of each inverter (D u1 , D u2 , D u3 Calculate the (Duty command value).

[0068] Similarly, the Duty Calculation Unit 35 calculates the V-phase voltage (v v_inv1 , v v_inv2 , v v_inv3 ) to DC voltage (V dc By dividing by ), the PWM signal of the V phase of each inverter (D v1 , D v2 , D v3 ) calculate the W phase voltage (v w_inv1 , v w_inv2 , v w_inv3 ) to DC voltage (V dc By dividing by ), the W-phase PWM signal (D) of each inverter is calculated. w1 , D w2 , D w3 Calculate ).

[0069] [Second Embodiment] Figure 6 is a diagram showing the control configuration of the control system for an open-wound motor according to the second embodiment. Figure 7 shows the voltage command value (v) of the first inverter 3 in the first U-phase inverter voltage calculation unit 36 ​​that constitutes the control system for an open-wound motor according to the second embodiment. u_inv1_1 * , α u_inv1_1 * ), the voltage command value (v) of the second inverter 4 u_inv2_1 * , α u_inv2_1 * ), the voltage command value (v) of the third inverter 5 u_inv3_1 * , α u_inv3_1 *Figure 8 is a vector diagram for calculating the voltage command value (v) of the first inverter 3 in the second U-phase inverter voltage calculation unit 37 which constitutes the control system of the open-wound motor of the second embodiment. u_inv1_2 * , α u_inv1_2 * ), the voltage command value (v) of the second inverter 4 u_inv2_2 * , α u_inv2_2 * ), the voltage command value (v) of the third inverter 5 u_inv3_2 * , α u_inv3_2 * This is a vector diagram for calculating ).

[0070] In the first embodiment, each inverter voltage is calculated by optimization calculation by the U-phase inverter voltage optimization calculation unit 33 as described above. However, motor control generally requires that calculations be completed within a calculation cycle of several tens of microseconds to several hundred microseconds.

[0071] If the motor control controller 23 has low computing power, computing resources may be concentrated on the optimization calculation described above, or the calculation may not be completed within the calculation cycle. Therefore, the second embodiment is configured to determine the voltage command value of each inverter with fewer computing resources.

[0072] In the second embodiment, the electrical angular frequency (ω) of the AC voltage of the first motor 1 and the second motor 2 re1 , ω re2 ) coincide with each other, and the amplitude (v) of the AC voltage of the first motor 1 and the second motor 2 u1 * , v u2 * ) are also in agreement with each other, and the voltage command value (v) of the first inverter 3 is equal to each other. u_inv1 * , α u_inv1 * ), the voltage command value (v) of the second inverter 4 uinv2 * , α u_inv2 * ), the voltage command value (v) of the third inverter 5 u_inv3 *, α u_inv3 * This document describes a method for calculating ( ).

[0073] Figure 6, like Figure 5, details the method for determining the inverter voltage command value for the U phase, but the same method can be used to calculate the values ​​for the V and W phases.

[0074] As shown in Figure 6, the second embodiment includes a first U-phase inverter voltage calculation unit 36, a second U-phase inverter voltage calculation unit 37, a comparator 38, and a selection unit 39, instead of the U-phase inverter voltage optimization calculation unit 33 of the first embodiment.

[0075] The first U-phase inverter voltage calculation unit 36 ​​and the second U-phase inverter voltage calculation unit 37 calculate the first amplitude command value (v) from the first d-q coordinate / three-phase AC converter 30. u1 * ) and the first phase command value (α u1 * The second amplitude command value (v) is input, and the second d-q coordinate / three-phase AC converter 31 is used to obtain the second amplitude command value (v u2 * ) and the second phase command value (α u2 * ) is entered.

[0076] The first U-phase inverter voltage calculation unit 36 ​​calculates the phase difference (α) between the AC voltage of the first motor 1 and the AC voltage of the second motor 2. diff =θ re2 -θ re1 ) is 0 ≤ α diff Using the vector diagram in Figure 7, which assumes that the relationship <π / 2[rad] is satisfied, the voltage command value of the first inverter 3 (v u_inv1_1 * , α u_inv1_1 * ), the voltage command value (v) of the second inverter 4 uinv2_1 * , α u_inv2_1 * ), the voltage command value (v) of the third inverter 5 u_inv3_1 * , α u_inv3_1 * ) is calculated as shown in equation (18)-(21).

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[0077] (18) The rightmost side of equation "v u1 * " is the amplitude command value (v) for the first motor 1 and the second motor 1. u1 * , v u2 * )

[0078] The second U-phase inverter voltage calculation unit 37 calculates the phase difference (α) between the AC voltage of the first motor 1 and the AC voltage of the second motor 2. diff =θ re2 -θ re1 ) is π / 2 ≤ α diff Using the vector diagram in Figure 8, which assumes that the relationship <π[rad] is satisfied, the voltage command value of the first inverter 3 (v u_inv1_2 * , α u_inv1_2 * ), the voltage command value (v) of the second inverter 4 uinv2_2 * , α u_inv2_2 * ), the voltage command value (v) of the third inverter 5 u_inv3_2 * , α u_inv3_2 * ) is calculated as shown in equation (22)-(26).

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[0079] Comparator 38 has a phase difference (α diff =θ re2 -θ re1 The phase difference (α) and comparison value (π / 2 [rad]) are input. The comparator 38 receives the phase difference (α) diff ) is 0 ≤ α diff If the relationship <π / 2[rad] is satisfied, a LOW judgment signal is output to the selection unit 39, and the phase difference (α diff ) is π / 2 ≤ α diff A HIGH determination signal is output to the selection unit 39 if the relationship ≤ π [rad] is satisfied.

[0080] The selection unit 39 receives the output of the first U-phase inverter voltage calculation unit 36 ​​(voltage command value of the first inverter 3 (v u_inv1_1 * , α u_inv1_1 * ), the voltage command value (v) of the second inverter 4 uinv2_1 * , α u_inv2_1 * ), the voltage command value (v) of the third inverter 5 u_inv3_1 * , α u_inv3_1 * )), Output of the second U-phase inverter voltage calculation unit 37 (Voltage command value of the first inverter 3 (v u_inv1_2 * , α u_inv1_2 * ), the voltage command value (v) of the second inverter 4 uinv2_2 * , α u_inv2_2 * ), the voltage command value (v) of the third inverter 5 u_inv3_2 * , α u_inv3_2 * A judgment signal (LOW or HIGH) is input.

[0081] When a determination signal (LOW) is input, the selection unit 39 selects the output of the first U-phase inverter voltage calculation unit 36 ​​and sets it to the voltage command value (v) of the first inverter 3. u_inv1 * , α u_inv1 * ), the voltage command value (v) of the second inverter 4 uinv2 * , α u_inv2 * ), the voltage command value (v) of the third inverter 5 u_inv3 * , α u_inv3 * The output is sent to the inverter instantaneous voltage calculation unit 34 (Figure 5) as follows.

[0082] When a determination signal (HIGH) is input, the selection unit 39 selects the output of the second U-phase inverter voltage calculation unit 37 and sets it to the voltage command value (v) of the first inverter 3. u_inv1 * , α u_inv1 * ), the voltage command value (v) of the second inverter 4 uinv2 * , α u_inv2 * ), the voltage command value (v) of the third inverter 5 u_inv3 * , α u_inv3 * The output is sent to the inverter instantaneous voltage calculation unit 34 (Figure 5) as follows.

[0083] In the second embodiment, the phase difference (α) between the AC voltage of the winding of the first motor 1 and the AC voltage of the winding of the second motor 2 is... diff Because voltage can be applied to the windings with the minimum inverter voltage command, regardless of the inverter's settings, the voltage utilization rate of each inverter is improved.

[0084] [Third Embodiment] Figure 9 is a diagram showing the control configuration of the control system for an open-wound motor according to the third embodiment. Figure 10 shows the PWM conversion unit 32 shown in Figure 9 with a correction coefficient (T compThis figure shows the configuration for calculating the phase difference (α) between the AC voltage of the winding of the first motor 1 and the AC voltage of the winding of the second motor 2. diff This figure shows the relationship between the available voltages of the first motor 1 and the second motor 2.

[0085] DC voltage (V) applied to the first inverter 3, the second inverter 4, and the third inverter 5 dc When the same is true, as shown in Figure 11, the phase difference (α) between the AC voltage of the winding of the first motor 1 and the AC voltage of the winding of the second motor 2 diff When ) is zero, the applicable voltage (usable voltage range) for the first motor 1 and the second motor 2 is DC voltage (V dc ) becomes, but the phase difference (α diff As the ) increases, it decreases monotonically, and the phase difference (α) diff When the voltage reaches 180 degrees (π rads), the voltage is 0.5V. dc It decreases to that point.

[0086] In this situation, the voltage required for the motor may increase sharply, such as when the rotational speed of the motor (first motor 1 or second motor 2) increases rapidly, causing a sharp increase in induced voltage, or when an excessive disturbance is input. If the currently applied voltage is close to the voltage that can be applied to the motor, there may not be enough margin to apply the above voltage to the motor, and in the worst case, control divergence may occur. In response to this, the third embodiment is configured to improve robustness against voltage fluctuations in the control system of an open-wound motor.

[0087] The control system of the open-wound motor in the third embodiment has the same configuration as in the first embodiment, but the PWM conversion unit 32 reduces the current difference (torque difference) between the first motor 1 and the second motor 2 by a torque correction coefficient (T comp The system is configured to calculate the first torque command value (T1) to be output to the first motor 1, and this value is input to the torque command / current command conversion unit 27. * ) and the second torque command value (T2) output to the second motor 2 * The sum of ) is the target torque (T * )

[0088] As shown in Figure 10, the PWM conversion unit 32 of the third embodiment uses a torque correction coefficient (T comp The configuration for outputting the ) includes a maximum value selection unit 40, an available voltage calculation unit 41, a divider 42, and a torque correction coefficient calculation unit 43.

[0089] The maximum value selection unit 40 receives a three-phase voltage command value (v) output to the first motor 1. u1 * , v v1 * , v w1 * ) and the three-phase voltage command value (v) output toward the second motor 2. u2 * , v v2 * , v w2 * ) is input, and the voltage with the largest absolute value among them is the maximum value (v max ) is output to the divider 42.

[0090] The available voltage calculation unit 41 calculates the DC voltage (V dc ) and phase difference (α diff =θ re2 -θ re1 ) is entered.

[0091] The available voltage calculation unit 41 calculates the available voltage (V) according to equation (27). max ) is calculated and output to the divider 42.

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[0092] The divider 42 receives the maximum value (v) output by the maximum value selection unit 40. max ) and the available voltage (V) calculated by the available voltage calculation unit 41 max ) is entered.

[0093] The divider 42 calculates the maximum value (v max ) available voltage (V max By dividing by ), the available voltage (V maxMaximum value (v) max ) ratio (v max / V max The system calculates the following and outputs it to the torque correction coefficient calculation unit 43.

[0094] The torque correction coefficient calculation unit 43 calculates the ratio (v) input from the divider 42. max / V max If ) is less than or equal to the first predetermined value A1, the torque correction coefficient (T comp The output is (=1). Note that the first predetermined value A1 is the voltage command value output to the first motor 1, the voltage command value output to the second motor 2, and the voltage command value output to each inverter, which are DC voltages (V dc Set the value to one that does not exceed ).

[0095] The torque correction coefficient calculation unit 43 calculates the ratio (v) input from the divider 42. max / V max When ) becomes larger than the first predetermined value A1, the torque correction coefficient (T comp Set the ratio (v) to a value lower than 1, and max / V max The larger the torque correction coefficient (T) becomes, the larger the torque correction coefficient (T comp Set the ratio (v) to decrease monotonically. max / V max When the torque correction coefficient (T) reaches a second predetermined value A2 which is greater than the first predetermined value A1, the torque correction coefficient (T comp Set ) to the minimum value (e.g., zero).

[0096] In Figure 10, the torque correction coefficient (T comp The change in the torque correction coefficient (T) is shown linearly, but the change in the torque correction coefficient (T) is shown linearly. comp ) is the DC voltage (V dc It is sufficient to set the value not to exceed ), and the change may be curvilinear.

[0097] Also, the torque correction coefficient (T comp ) is the ratio (v max / V max Even if you store map data relating to ) in memory beforehand and refer to this map data to find the ratio (v max / Vmax It can also be obtained by creating a function that expresses the relationship between ( ) and and calculating it.

[0098] Torque correction coefficient (T) calculated by PWM conversion unit 32 comp ) is input to the torque command / current command conversion unit 27, and the difference in amplitude or phase difference (β) between the first AC current supplying power to the first motor 1 and the second AC current supplying power to the second motor 2 is input. diff Correct the value in a way that reduces at least one of the two values.

[0099] As described above, the torque command / current command conversion unit 27 has the relationship between current and torque as map data, and therefore outputs a first torque command value (T1) to the first motor 1. * ) and the second torque command value (T2) output to the second motor 2 * By reducing the difference between the first AC current and the second AC current, the difference in amplitude or phase difference (β) can be reduced. diff It is possible to reduce the size of ).

[0100] First torque command value (T1 * ) and the second torque command value (T2 * ) is the target torque (T * ), torque correction coefficient (T comp ), the difference between the first torque command value and the second torque command value (T diff * It can be expressed as in equation (28) using ).

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[0101] From equation (28), the torque correction coefficient (T comp If ) is 1, that is, if no torque correction is applied, the first torque command value (T1) output to the first motor 1 is * ) and the second torque command value (T2) output to the second motor 2 * The sum of ) is the target torque (T * ) becomes the first torque command value (T1 * ) and the second torque command value (T2 * The difference between ) is T diff* This is the result.

[0102] On the other hand, the torque correction coefficient (T comp When ) becomes less than 1, the above sum becomes the target torque (T * ) remains the same, and the above difference is T diff * It becomes smaller, and the torque correction coefficient (T comp When ) is 0, the above difference becomes zero. This creates a margin in the required voltage relative to the usable voltage range, improving robustness against voltage fluctuations and allowing the required torque to be output even when voltage fluctuations occur.

[0103] As shown in Figure 11, for example, the torque correction coefficient (T comp The phase difference (α) between the AC voltage applied to the winding of the first motor 1 before applying the AC voltage applied to the second motor 2 diff ) is 105[deg] and the AC voltage required for the first motor 1 and the second motor 2 is 0.57V dc When the first motor 1 and the second motor 2 are driven at the operating point G, the usable voltage at the same phase difference is 0.625V. dc Therefore, the voltage margin is 0.625V dc -0.57V dc =0.055V dc This is the result.

[0104] On the other hand, the torque correction coefficient (T) is applied to the operating point G. comp By applying ), the phase difference (α diff When the first motor 1 and the second motor 2 are driven at the operating point H where the phase difference is approximately 45 degrees, the usable voltage at the same phase difference is 0.93V. dc Therefore, the voltage margin is 0.93V dc -0.57V dc = 0.36V dc Therefore, by improving the voltage margin, the stability required to meet the demanded torque can be increased.

[0105] [Example of conduction loss] Figure 12 shows an example of the conduction loss of an inverter in a control system for an open-wound motor of a comparative example. Figure 13 shows a first example of the conduction loss of an inverter in a control system for an open-wound motor of this embodiment. Figure 14 shows a second example of the conduction loss of an inverter in a control system for an open-wound motor of this embodiment.

[0106] Figures 12-14 show only single-phase systems for simplicity, but in reality, they are composed of three or more phases.

[0107] The comparative example shown in Figure 12 has the first motor 1 and second motor 2 of this embodiment, but one end of the winding of the first motor 1 (MTR1) is connected to the first inverter 3 (INV1-1), and the other end of the winding of the first motor 1 (MTR1) is connected to the fourth inverter 5a (INV1-2). Also, one end of the winding of the second motor 2 (MTR2) is connected to the second inverter 4 (INV2-1), and the other end of the winding of the second motor 2 (MTR2) is connected to the fifth inverter 5b (INV2-2). The fourth inverter 5a (INV1-2) and the fifth inverter 5b (INV2-2) operate independently of each other. The current capacity of the first inverter 3, the second inverter 4, the fourth inverter 5a, and the fifth inverter 5b are all set to the same capacity (x [kW]).

[0108] The conduction loss of the fourth inverter 5a is the alternating current (i) flowing through the first motor 1 (MTR1). MTR1 ) That is, the alternating current (i) flowing through the fourth inverter 5a INV1-2 The conduction loss of the fifth inverter 5b is determined by the alternating current (i) flowing through the second motor 2 (MTR2). MTR2 ) That is, the alternating current (i) flowing through the fifth inverter 5b INV2-2 ) will be determined by.

[0109] Here, the alternating current (i INV1-2 ) and alternating current (i INV2-2If the maximum current values ​​of the two switching elements constituting the fourth inverter 5a are the same (i=1.0[pu]), and R is the resistance of the series circuit obtained by connecting the two switching elements constituting the fourth inverter 5a in series, then the conduction loss in the comparative example is Ri 2 +Ri 2 =2Ri 2 The total value will be, for example, 1.0[pu].

[0110] In this embodiment (Figures 13 and 14), one end of the winding of the first motor 1 (MTR1) is connected to the first inverter 3 (INV1), and one end of the winding of the second motor 2 (MTR2) is connected to the second inverter 4 (INV2). The other end of the winding of the first motor 1 (MTR1) and the other end of the winding of the second motor 2 (MTR2) are connected in parallel to the third inverter 5 (INV3). In the first example of this embodiment (Figure 13), the current capacity of the first inverter 3 and the second inverter 4 is set to x [kW], and the current capacity of the third inverter 5 is set to 2x [kW]. In the second example of this embodiment (Figure 14), the current capacity of the first inverter 3 and the second inverter 4 is set to x [kW], and the current capacity of the third inverter 5 is set to √2x [kW].

[0111] In Figures 13 and 14, the first alternating current (i) flowing through the first motor 1 MTR1 ) and the second alternating current (i) flowing to the second motor 2 MTR2 The maximum value of ) is 1.0 [pu].

[0112] In Figures 13 and 14, the first alternating current (i) flowing through the first motor 1 MTR1 ) and the second alternating current (i) flowing to the second motor 2 MTR2 ) are when the frequencies are the same and the phase difference (β) diff Although the value is 90 [deg], it is not limited to this, and the phase difference (β diff This is applicable when ) is greater than 0 [deg].

[0113] Figures 13 and 14 show the alternating current (i) flowing through the third inverter 5. INV3 ) is the first alternating current (i) flowing through the first motor 1. MTR1 ) and the second alternating current (i) flowing through the second motor 2 MTR2 The third alternating current (i) is the sum of the three currents. INV3 =i MTR1 +i MTR2 It is represented as follows:

[0114] Therefore, the phase difference (β) between the first AC current and the second AC current is diff If ) is greater than 0, there is a time period (i) in which the direction of the current flowing through one motor and the direction of the current flowing through the other motor are opposite. MTR1 and i MTR2 A period occurs in which one of the two is positive and the other is negative. During this period, according to Kirchhoff's current law, a current component is generated that flows directly back from one motor to the other, and furthermore, this current component generates a third alternating current (i INV3 A timing occurs when this becomes zero. Therefore, a timing also occurs when the conduction loss in the third inverter 5 becomes zero, and the average value of the conduction loss in the third inverter 5 is also reduced.

[0115] Furthermore, if the maximum current of the third inverter 5 (INV3) is the sum of the maximum currents of the first inverter 3 (INV1) and the second inverter 4 (INV2), it becomes equivalent to connecting the switching elements (series circuits) of the first inverter 3 (INV1) and the second inverter 4 (INV2) in parallel. As a result, the current flowing through the third inverter 5 (INV3) becomes equal to the current being divided among the switching elements, thus reducing the conduction loss of the third inverter 5 (INV3). Due to the effects of the above two points, the conduction loss of the inverter can be reduced in this embodiment.

[0116] The first alternating current (i MTR1 ) and second alternating current (i MTR2 The maximum current value (amplitude) of ) is the same (i=1.0[pu]), and the first AC current (i MTR1 ) and the second alternating current (i MTR2 When the phase difference with ) is 90 [deg], the third AC current (i INV3The maximum current value (amplitude) of ) is √i = √2 [pu].

[0117] In the first example shown in Figure 13, as described above, the current capacity of the third inverter 5 is 2x [kW], which is twice the current capacity of the first inverter 3 and the second inverter 4. Therefore, the equivalent circuit of the third inverter 5 includes two series circuits applied in the first inverter 3 or the second inverter 4, and each phase is assigned a circuit in which these two series circuits are connected in parallel.

[0118] Therefore, a current of (√2 / 2)i flows through one series circuit of the third inverter 5, and the average conduction loss of the third inverter 5 is R((√2 / 2)i). 2 +R((√2 / 2)i) 2 =Ri 2 This becomes 0.5[pu], which is half of the comparative example.

[0119] Figure 13 shows the instantaneous value of the conduction loss of the third inverter 5, and the third AC current (i INV3 When the current is at its maximum, the conduction loss is at its maximum (1[pu]), and the third AC current (i INV3 When ) is zero, the conduction loss is zero, but the average value of the conduction loss is 0.5 [pu] as described above.

[0120] In the second example shown in Figure 14, as described above, the current capacity of the third inverter 5 is √2x [kW], so the third inverter 5 includes two series circuits with a resistance of √2R, and each phase is assigned a circuit in which these two series circuits are connected in parallel.

[0121] Therefore, the conduction loss (average value) of the third inverter 5 is √2R((√2 / 2)i) 2 +√2R((√2 / 2)i) 2 =√2Ri 2 This results in 0.71[pu], which is 0.71 times that of the comparative example.

[0122] Figure 14, like Figure 13, shows the instantaneous value of the conduction loss of the third inverter 5, but the third AC current (iINV3 When ) is at its maximum, the conduction loss is at its maximum (√2[pu]), and the third AC current (i INV3 When ) is zero, the conduction loss is zero, but the average value of the conduction loss is 0.71 [pu] as described above.

[0123] [Effects of this embodiment] The control method for the open-winding motor of this embodiment includes an open-winding first motor 1 and a second motor 2 having independent multi-phase windings as stators, a first inverter 3 connected to one end of the winding of the first motor 1, a second inverter 4 connected to one end of the winding of the second motor 2, and a third inverter 5 in which the other end of the winding of the first motor 1 and the other end of the winding of the second motor 2 are connected in parallel, and a first AC current (i) output from the first inverter 3. MTR1 ) and the second AC current (i) output from the second inverter 4 MTR2 ) and the sum of the currents (i MTR1 +i MTR2 The third AC current (i) is input to the third inverter 5. INV3 A control method for an open-winding motor, which controls the first inverter 3, second inverter 4, and third inverter 5 so that the first AC current (i MTR1 ) and the second alternating current (i MTR2 ) and the phase difference (β diff This causes ) to occur.

[0124] By using the above method and sharing the switching elements that make up the inverter, it becomes possible to issue AC voltage commands that correspond to regions where the AC voltage cannot be applied as commanded due to a reduction in the degree of freedom of voltage, and furthermore, the first AC current (i MTR1 ) and the second alternating current (i MTR2 ) and the phase difference (β diff By generating ), the conduction loss of the switching element can be reduced.

[0125] In this embodiment, the maximum phase current of the first motor 1 is set to a predetermined first maximum current value (I max1 The maximum phase current of the second motor 2 is set to a predetermined second maximum current value (Imax2 It is set to ) and the first AC current (i MTR1 ) is the first maximum current value (I max1 ) when the phase difference (β) required to achieve the maximum output of the first motor 1 is achieved. diff The minimum value of ) and the second AC current (i MTR2 ) is the second maximum current value (I max2 When the phase difference (β) is such that the maximum output required for the second motor 2 is achieved, diff Of the minimum values ​​of ), the one with the lower value is the phase difference (β diff The minimum value of (β) diff_min Set it to ).

[0126] The above method makes it possible to achieve the maximum output required for the first motor 1 and the second motor 2. Also, the phase difference (β diff The minimum value of (β) diff_min By driving the first motor 1 and the second motor 2 with a current of ) or higher, the maximum output required for the first motor 1 and the second motor 2 is supplied to the third inverter 5 by the third AC current (i INV3 This can be achieved under the condition that ) is minimized.

[0127] In this embodiment, the maximum phase current of the first motor 1 is set to a predetermined first maximum current value (I max1 The maximum phase current of the second motor 2 is set to a predetermined second maximum current value (I max2 The output of the first motor 1 is set to a phase difference (β diff In a coordinate space where the coordinate axes are the output of (the first motor 1) and the phase difference (β diff The first characteristic curve (Figure 3) shows that the output (of the first motor 1) decreases monotonically as the first maximum current value (I) increases, and the first maximum current value (I) max1 The first operating point (e.g., operating point A) in the first characteristic curve (Figure 3) shows that the output (of the first motor 1) increases monotonically with increasing β, and the output of the second motor 2 is represented as the first operating point (e.g., operating point A) in coordinate space with a phase difference (β). diff The second characteristic curve (Figure 3) shows that the output (of the second motor 2) decreases monotonically as the second maximum current value (I) increases, and the second maximum current value (I) max2In the case where the output of the second motor 2 increases monotonically with the increase of the first AC current (i) is represented as the second operating point (e.g., operating point B) in the second characteristic curve (Figure 3), the first AC current (i) is represented as the second operating point (e.g., operating point B) in the second characteristic curve (Figure 3). MTR1 ) is the first maximum current value (I max1 The phase difference (β) represented by the first operating point (operating point A) that includes the maximum output required for the first motor 1 at that time diff ) and the second alternating current (i MTR2 ) is the second maximum current value (I max2 The phase difference (β) represented by the second operating point (operating point B) that includes the maximum output required for the second motor 2 at that time diff The phase difference (β) is the one with the lower value between ) and ). diff The minimum value of (β) diff_min Set it to ).

[0128] By the above method, the phase difference (β) that can achieve the maximum output required for the first motor 1 and the second motor 2 can be obtained. diff The minimum value of (β) diff_min ) can be set up in a simple way.

[0129] In this embodiment, the first maximum current value is I max1 And the second maximum current value is I max2 Let the phase difference (β diff The minimum value of ) is β diff_min The maximum current value of the third inverter 5 is set to I max3 In that case, I max3 Set it so that equation (29) is satisfied.

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[0130] By the above method, the phase difference (β) that can achieve the maximum output required for the first motor 1 and the second motor 2 can be obtained. diff The minimum value of (β) diff_min If ) is greater than 0, the first maximum current value (I max1 ) and the second maximum current value (I) flowing to the second motor 2 max2 The current capacity of the third inverter 5 can be reduced by the sum of ) (see Figure 14). Also, the first maximum current value (I max1 ) and the second maximum current value (Imax2 If ) is known, the current capacity of the third inverter 5 can be reduced to the maximum extent from equation (29).

[0131] In this embodiment, the maximum phase current of the first motor 1 is set to a predetermined first maximum current value (I max1 The maximum phase current of the second motor 2 is set to a predetermined second maximum current value (I max2 It is set to ) and the first AC current (i MTR1 ) is the first maximum current value (I max1 The minimum phase difference required to achieve the continuous rated output of the first motor 1 when ) and the second AC current (i MTR2 ) is the second maximum current value (I max2 When ) is the case, the lower of the minimum values ​​of the phase difference that realize the continuous rated output required for the second motor 2 is the phase difference (β diff The maximum value (β) diff_max Set it to ).

[0132] The above method makes it possible to achieve the continuous rated output required for the first motor 1 and the second motor 2. Also, the first AC current (i MTR1 ) and the second alternating current (i MTR2 ) Phase difference (β diff ) is the maximum value (β diff_max By driving the first motor 1 and the second motor 2 to the following conditions, the minimum required output of the first motor 1 and the second motor 2 can be constantly achieved.

[0133] In this embodiment, the maximum phase current of the first motor 1 is set to a predetermined first maximum current value (I max1 The maximum phase current of the second motor 2 is set to a predetermined second maximum current value (I max2 The output of the first motor 1 is set to a phase difference (β diff In a coordinate space where the coordinate axes are the output of (the first motor 1) and the phase difference (β diff The first characteristic curve (Figure 3) shows that the output (of the first motor 1) decreases monotonically as the first maximum current value (I) increases, and the first maximum current value (I) max1The first operating point (e.g., operating point D) in the first characteristic curve (Figure 3) shows that the output (of the first motor 1) increases monotonically with increasing β, and the output of the second motor 2 is represented as the first operating point (e.g., operating point D) in coordinate space with a phase difference (β). diff The second characteristic curve (Figure 3) shows that the output (of the second motor 2) decreases monotonically as the second maximum current value (I) increases, and the second maximum current value (I) max2 In the case where the output of the second motor 2 increases monotonically with the increase of the first AC current (i) is represented as the second operating point (e.g., operating point E) in the second characteristic curve (Figure 3), the first AC current (i) is represented as the second operating point (e.g., operating point E) in the second characteristic curve (Figure 3). MTR1 ) is the first maximum current value (I max1 ) The phase difference (β) represented by the first operating point (operating point D) which includes the continuous rated output required for the first motor 1 at that time diff ) and the second alternating current (i MTR2 ) is the second maximum current value (I max2 ) The phase difference (β) represented by the second operating point (operating point E) which includes the continuous rated output required for the second motor 2 at that time diff The phase difference (β) is the one with the lower value between ) and ). diff The maximum value (β) diff_max Set it to ).

[0134] By the above method, the first AC current (i) is generated to achieve the continuous rated output required for the first motor 1 and the second motor 2. MTR1 ) and the second alternating current (i MTR2 ) Phase difference (β diff The maximum value (β) diff_max ) can be set up in a simple way.

[0135] In this embodiment, the first inverter 3 sets the first voltage command value (v u_inv1 , v v_inv1 , v w_inv1 Based on this, power is exchanged between the first DC power supply (DC power supply 6) and the first motor 1, and the second inverter 4 controls the second voltage command value (v u_inv2 , v v_inv2 , v w_inv2 Based on this, power is exchanged between the second DC power supply (DC power supply 6) and the second motor 2, and the third inverter 5 controls the third voltage command value (v u_inv3 , v v_inv3 , v w_inv3Based on this, power is exchanged between the third DC power supply (DC power supply 6) and the first motor 1 and the second motor 2, and the first voltage command value (v u_inv1 , v v_inv1 , v w_inv1 ) and the second voltage command value (v u_inv2 , v v_inv2 , v w_inv2 ) between phase differences (α diff When generating ), the maximum value (v) of the output voltage of the first inverter 3 max The first voltage command value (v) is set such that the maximum output voltage of the second inverter 4 and the maximum output voltage of the third inverter 5 are each minimized. u_inv1 , v v_inv1 , v w_inv1 ), second voltage command value (v u_inv2 , v v_inv2 , v w_inv2 ), 3rd voltage command value (v u_inv3 , v v_inv3 , v w_inv3 Set ).

[0136] By using the above method, the voltage applied to the first motor 1 and the second motor 2 can be maximized with the minimum voltage command value, thereby improving the voltage utilization rate.

[0137] In this embodiment, the electrical angular frequencies (ω) of the first motor 1 and the second motor 2 are re1 , ω re2 ) and voltage amplitude (v u1 , v u2 ) match, and the first voltage command value (v u_inv1 ), second voltage command value (v u_inv2 ), 3rd voltage command value (v u_inv3 The electrical angular frequencies of ) match, and the phase difference (α diff When the phase difference (α) is less than or equal to π / 2, diff ) to α diff When this is the case, the phase (α) of the AC voltage applied to the first inverter 3 u_inv1 * ) is the voltage phase (θ) of the first motor 1 re1 ) against α diff / 2 delay ((19) equation), the phase (α) of the AC voltage applied to the second inverter 4 u_inv1 *) is the voltage phase (θ) of the second motor 2 re2 ) against α diff / 2 lead ((20) equation), the AC voltage applied to the third inverter 5 is in opposite phase (-α u_inv3 * ) is the voltage phase (θ) of the first motor 1 re1 ) against α diff Set it to advance by / 2 ((21) formula).

[0138] The above method improves the voltage utilization rate of each inverter by allowing voltage to be applied to the windings with the minimum inverter voltage command when the phase difference between the AC voltages of the first motor 1 and the second motor 2 is within 90 degrees. Furthermore, the voltage command can be determined with fewer computing resources.

[0139] In this embodiment, the electrical angular frequencies (ω) of the first motor 1 and the second motor 2 are re1 , ω re2 ) and voltage amplitude (v u1 , v u2 ) match, and the first voltage command value (v u_inv1 ), second voltage command value (v u_inv2 ), 3rd voltage command value (v u_inv3 The electrical angular frequencies of ) match, and the phase difference (α diff When the phase difference (α) is greater than π / 2, diff ) to α diff When this is the case, the phase (α) of the AC voltage applied to the first inverter 3 u_inv1 * ) is the voltage phase (θ) of the first motor 1 re1 ) for (π / 2)-(α diff / 2) Delay ((24) equation), the phase (α) of the AC voltage applied to the second inverter 4 u_inv2 * ) is the voltage phase (θ) of the second motor 2 re2 ) for (π / 2)-(α diff / 2) Advance, and the AC voltage applied to the third inverter 5 is in the opposite phase (-α) u_inv1 * ) is the voltage phase (θ) of the first motor 1 re1 ) against α diff Set it to advance by / 2.

[0140] The above method improves the voltage utilization rate of each inverter by allowing voltage to be applied to the windings with the minimum inverter voltage command when the phase difference between the AC voltages of the first motor 1 and the second motor 2 is greater than 90 degrees. Furthermore, it allows each voltage command value to be determined with fewer computing resources.

[0141] In this embodiment, the electrical angular frequencies (ω) of the first motor 1 and the second motor 2 are re1 , ω re2 ) and voltage amplitude (v u1 , v u2 ) match, and the first voltage command value (v u_inv1 ), second voltage command value (v u_inv2 ), 3rd voltage command value (v u_inv3 When the electrical angular frequencies of ) are the same, the phase difference (α diff ) to α diff When this is the case, the phase (α) of the AC voltage applied to the first inverter 3 u_inv1 * ) is the voltage phase (θ) of the first motor 1 re1 ) against α diff / 2 delay ((19) equation), the phase (α) of the AC voltage applied to the second inverter 4 u_inv2 * ) is the voltage phase (θ) of the second motor 2 re2 ) against α diff / 2 lead ((20) equation), the AC voltage applied to the third inverter 5 is in opposite phase (-α u_inv3 * ) is the voltage phase (θ) of the first motor 1 re1 ) against α diff The first state (decision signal LOW) is set to advance by 2 (equation (21)), and the phase (α) of the AC voltage applied to the first inverter 3 is set to advance by 2. u_inv1 * ) is the voltage phase (θ) of the first motor 1 re1 ) for (π / 2)-(α diff / 2) Delay ((24) equation), the phase (α) of the AC voltage applied to the second inverter 4 u_inv2 * ) is the voltage phase (θ) of the second motor 2 re2 ) for (π / 2)-(α diff / 2) Advance ((Equation 25)), the AC voltage applied to the third inverter 5 is in opposite phase (-α u_inv3 * ) is the voltage phase (θ) of the first motor 1 re1 ) against α diff When it is possible to switch between the first state (decision signal is HIGH) and the second state, which is set to advance by π / 2 (equation (26)), the first state is set when the phase difference (αdiff) is π / 2 or less, and the second state is set when the phase difference (αdiff) is greater than π / 2.

[0142] By the above method, the phase difference (β diff ) According to the first voltage command value (v u_inv1 ), second voltage command value (v u_inv2 ), 3rd voltage command value (v u_inv3 By switching the calculation method of the phase difference (β), diff Regardless of the inverter voltage command, voltage can be applied to the windings of the first motor 1 and the second motor 2 with the minimum inverter voltage command. This always improves the voltage utilization rate of each inverter. In addition, the voltage command values ​​can be determined with fewer computing resources.

[0143] In this embodiment, the power supply voltage (DC voltage (V) of the first DC power supply (DC power supply 6), the second DC power supply (DC power supply 6), and the third DC power supply (DC power supply 6) dc With the values ​​(T1) match, the torque of the first motor 1 (first torque command value (T1) * )) and the torque of the second motor 2 (second torque command value (T2 * The sum of )) is the target torque (T * The first voltage command value (v) is set to ) u_inv1 ), second voltage command value (v u_inv2 ), 3rd voltage command value (v u_inv3 When controlling the motor, the voltage phase difference between the first motor 1 and the second motor 2 is α diff The power supply voltage (DC voltage (V dc )) to V dc The maximum voltage that the first motor 1 and the second motor 2 can output is set to V max When V max The function is defined as shown in equation (30), and the maximum phase voltage of the first motor 1 and the second motor 2 is vmax The first voltage command value, the second voltage command value, and the third voltage command value are set to the V dc Let A1 be the gain set so as not to exceed v max >A1·V max In this case, the first alternating current (i MTR1 ) and the second alternating current (i MTR2 The difference in amplitude, or phase difference (α) diff ), correct in a way that reduces at least one of them.

number

[0144] By the above method, the first alternating current (i MTR1 ) and the second alternating current (i MTR2 The difference in amplitude of ) is reduced and the phase difference (α diff By reducing this value, a margin of voltage is created in the required voltage relative to the usable voltage range (voltage margin increases), improving robustness against voltage fluctuations and enabling the output of the required torque even when voltage fluctuations occur.

[0145] The control system for the open-winding motor of this embodiment includes a first motor 1 and a second motor 2, both open-winding motors having independent multi-phase windings as stators; a first inverter 3 connected to one end of the winding of the first motor 1; a second inverter 4 connected to one end of the winding of the second motor 2; a third inverter 5 connected in parallel to the other end of the winding of the first motor 1 and the other end of the winding of the second motor 2; and a first AC current (i) output from the first inverter 3. MTR1 ) and the second AC current (i) output from the second inverter 4 MTR2 ) and the sum of the currents (i MTR1 +i MTR2 The third AC current (i) is input to the third inverter 5. INV3 A control system for an open-winding motor, including a control unit (motor control controller 23) that controls the first inverter 3, second inverter 4, and third inverter 5 so that the first AC current (i MTR1) and the second alternating current (i MTR2 ) and the phase difference (β diff This causes ) to occur.

[0146] With the above configuration, by sharing the switching elements that make up the inverter, it becomes possible to issue AC voltage commands that correspond to regions where the AC voltage cannot be applied as commanded due to a reduction in the degree of freedom of voltage, and furthermore, the first AC current (i MTR1 ) and the second alternating current (i MTR2 ) and the phase difference (β diff By generating ), the conduction loss of the switching element can be reduced.

[0147] Although embodiments of the present invention have been described above, these embodiments represent only a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate. [Explanation of Symbols]

[0148] 1. First motor, 2. Second motor, 3. First inverter, 4. Second inverter, 5. Third inverter, 23. Motor control controller.

Claims

1. An open-winding type first motor and a second motor having independent multi-phase windings as stators, A first inverter connected to one end of the winding of the first motor, A second inverter connected to one end of the winding of the second motor, The third inverter includes the other end of the winding of the first motor and the other end of the winding of the second motor, connected in parallel. A control method for an open-winding motor, comprising controlling the first inverter, the second inverter, and the third inverter such that the sum of the first AC current output from the first inverter and the second AC current output from the second inverter becomes the third AC current input to the third inverter, A control method for an open-winding motor that generates a phase difference between the first AC current and the second AC current.

2. The maximum phase current of the first motor is set to a predetermined first maximum current value. The maximum phase current of the second motor is set to a predetermined second maximum current value. The minimum value of the phase difference that achieves the maximum output required for the first motor when the first AC current is the first maximum current value, The control method for an open-winding motor according to claim 1, wherein the minimum value of the phase difference that realizes the maximum output required for the second motor when the second AC current is the second maximum current value is set to the lower of the minimum values ​​of the phase difference.

3. The maximum phase current of the first motor is set to a predetermined first maximum current value. The maximum phase current of the second motor is set to a predetermined second maximum current value. The output of the first motor is represented as the first operating point in a first characteristic curve in a coordinate space where the phase difference and the output are the coordinate axes, where the output monotonically decreases with increasing phase difference, and where the output monotonically increases with increasing first maximum current value. When the output of the second motor is represented as the second operating point on the second characteristic curve in the coordinate space where the output monotonically decreases with increasing phase difference and the output monotonically increases with increasing second maximum current, The phase difference represented by the first operating point, which includes the maximum output required for the first motor when the first AC current is at its first maximum current value, The control method for an open-winding motor according to claim 1, wherein the lower of the following two values ​​is set as the minimum value of the phase difference: the phase difference represented by the second operating point which includes the maximum output required for the second motor when the second AC current is the second maximum current value, and the phase difference represented by the second operating point which includes the maximum output required for the second motor.

4. The above-mentioned first maximum current value is I ｍａｘ１ Let the second maximum current value be I ｍａｘ２ Let the minimum value of the phase difference be β. ｄｉｆｆ＿ｍｉｎ The maximum current value of the third inverter is set to I ｍａｘ３ In that case, the above I ｍａｘ３ A control method for an open-winding motor according to claim 2 or 3, wherein the motor is set to satisfy equation (1). [Math 1]

5. The maximum phase current of the first motor is set to a predetermined first maximum current value. The maximum phase current of the second motor is set to a predetermined second maximum current value. The minimum value of the phase difference that realizes the continuous rated output required for the first motor when the first AC current is the first maximum current value, The control method for an open-winding motor according to claim 1, wherein the lower of the minimum values ​​of the phase difference that realize the continuous rated output required for the second motor when the second AC current is the second maximum current value is set to the maximum value of the phase difference.

6. The maximum phase current of the first motor is set to a predetermined first maximum current value. The maximum phase current of the second motor is set to a predetermined second maximum current value. The output of the first motor is represented as the first operating point in a first characteristic curve in a coordinate space where the phase difference and the output are the coordinate axes, where the output monotonically decreases with increasing phase difference, and where the output monotonically increases with increasing first maximum current value. When the output of the second motor is represented as the second operating point on the second characteristic curve in the coordinate space where the output monotonically decreases with increasing phase difference and the output monotonically increases with increasing second maximum current, The phase difference represented by the first operating point, which includes the continuous rated output required for the first motor when the first AC current is at its first maximum current value, The control method for an open-winding motor according to claim 1, wherein the lower of the two values, the phase difference represented by the second operating point including the continuous rated output required for the second motor when the second AC current is the second maximum current value, and the maximum value of the phase difference, is set.

7. The first inverter exchanges power between the first DC power supply and the first motor based on the first voltage command value. The second inverter exchanges power between the second DC power supply and the second motor based on the second voltage command value. The third inverter exchanges power between the third DC power supply and the first motor and the second motor based on the third voltage command value. When generating the phase difference between the first voltage command value and the second voltage command value, The control method for an open-winding motor according to claim 1, wherein the first voltage command value, the second voltage command value, and the third voltage command value are set such that the maximum output voltage of the first inverter, the maximum output voltage of the second inverter, and the maximum output voltage of the third inverter are each minimized.

8. When the electrical angular frequencies and voltage amplitudes of the first motor and the second motor are the same, the electrical angular frequencies of the first voltage command value, the second voltage command value and the third voltage command value are the same, and the phase difference is π / 2 or less, the phase difference is α ｄｉｆｆ When that happens, The phase of the AC voltage applied to the first inverter is α relative to the voltage phase of the first motor. ｄｉｆｆ / 2 delay, The phase of the AC voltage applied to the second inverter is α relative to the voltage phase of the second motor. ｄｉｆｆ / Move 2, The reverse phase of the AC voltage applied to the third inverter is α with respect to the voltage phase of the first motor ｄｉｆｆ The control method of the open winding type motor according to claim 7, which is set to advance by α / 2

9. When the electrical angular frequencies and voltage amplitudes of the first motor and the second motor are the same, the electrical angular frequencies of the first voltage command value, the second voltage command value and the third voltage command value are the same, and the phase difference is greater than π / 2, the phase difference is α ｄｉｆｆ When that happens, The phase of the AC voltage applied to the first inverter is (π / 2) - (α) relative to the voltage phase of the first motor. ｄｉｆｆ / 2) Delay, The phase of the AC voltage applied to the second inverter is (π / 2) - (α) relative to the voltage phase of the second motor. ｄｉｆｆ / 2) Proceed, The opposite phase of the AC voltage applied to the third inverter is α relative to the voltage phase of the first motor. ｄｉｆｆ A control method for an open-winding motor according to claim 7, which is set to advance by 2.

10. When the electrical angular frequencies and voltage amplitudes of the first motor and the second motor are the same, and the electrical angular frequencies of the first voltage command value, the second voltage command value, and the third voltage command value are the same, The aforementioned phase difference is α ｄｉｆｆ When that happens, The phase of the AC voltage applied to the first inverter is α relative to the voltage phase of the first motor. ｄｉｆｆ / 2 delay, The phase of the AC voltage applied to the second inverter is α relative to the voltage phase of the second motor. ｄｉｆｆ / Move 2, The opposite phase of the AC voltage applied to the third inverter is α relative to the voltage phase of the first motor. ｄｉｆｆ The first state is set to move forward by / 2, The phase of the AC voltage applied to the first inverter is (π / 2) - (α) relative to the voltage phase of the first motor. ｄｉｆｆ / 2) Delay, The phase of the AC voltage applied to the second inverter is (π / 2) - (α) relative to the voltage phase of the second motor. ｄｉｆｆ / 2) Proceed, The opposite phase of the AC voltage applied to the third inverter is α relative to the voltage phase of the first motor. ｄｉｆｆ In a case where it is possible to switch between a second state, which is set to advance by 2, The first state is set when the phase difference is π / 2 or less. The control method for an open-wound motor according to claim 7, wherein the second state is set when the phase difference is greater than π / 2.

11. When the power supply voltages of the first DC power supply, the second DC power supply, and the third DC power supply are matched, and the first voltage command value, the second voltage command value, and the third voltage command value are controlled so that the sum of the torque of the first motor and the torque of the second motor equals the target torque, The voltage phase difference between the first motor and the second motor is α ｄｉｆｆ The power supply voltage is set to V ｄｃ The maximum voltage that the first motor and the second motor can output is set to V ｍａｘ When V ｍａｘ It is defined as in equation (2), The maximum phase voltage of the first motor and the second motor is v ｍａｘ The first voltage command value, the second voltage command value, and the third voltage command value are V ｄｃ Let A1 be the gain set so as not to exceed v ｍａｘ > A1・V ｍａｘ The control method for an open-winding motor according to claim 7, wherein, in the case of this, the difference in amplitude between the first AC current and the second AC current, or the phase difference, is corrected in a direction that reduces at least one of them. [Math 2]

12. An open-winding type first motor and a second motor having independent multi-phase windings as stators, A first inverter connected to one end of the winding of the first motor, A second inverter connected to one end of the winding of the second motor, A third inverter is provided, in which the other end of the winding of the first motor and the other end of the winding of the second motor are connected in parallel. A control system for an open-winding motor, comprising: a control unit that controls the first inverter, the second inverter, and the third inverter such that the sum of the first AC current output from the first inverter and the second AC current output from the second inverter becomes the third AC current input to the third inverter; The control unit, A control system for an open-winding motor that generates a phase difference between the first AC current and the second AC current.

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