Control device for synchronous motors

Abstract

The present invention provides a control device for a synchronous motor that can suppress the deterioration of battery life due to current ripple while also suppressing the deterioration of energy efficiency. [Solution] In the electronic control device 90 of a synchronous motor 20 equipped with a rotor 24 field-magnetized with permanent magnets 24m, (a) vector control is performed using an orthogonal vector coordinate system with a d-axis along the direction of the magnetic flux created by the magnetic poles of the rotor 24 and a q-axis electrically 90 degrees ahead in phase with respect to the d-axis, and (b) if any of the 6n-th order (n is a natural number) forcing forces F exceeds a predetermined allowable value F_jdg and the absolute value |Δf| of the difference between the frequency f of the 6n-th order and the electrical resonant frequency fr is less than or equal to a predetermined frequency difference Δf_jdg, a predetermined feedforward control based on the electrical angle θe is performed to suppress the current ripple of the synchronous motor 20, and otherwise the predetermined feedforward control is not performed.

Description

[[TECHNICAL FIELD]]

[0001] The present invention relates to a control device for a synchronous motor including a rotor that is field-excited by a permanent magnet. [[BACKGROUND ART]]

[0002] A technique is known for a control device for a synchronous motor, in which, in order to reduce loss of the synchronous motor within a specific rotational speed range, harmonic components are suppressed only for orders whose frequency at the specific rotational speed falls within a frequency range that causes an increase in loss occurring in the synchronous motor. For example, this is the case with the synchronous motor control device described in Patent Document 1. Factors causing generation of harmonic components in a synchronous motor include, for example, variation in the strength of permanent magnets that excite the rotor. [[PRIOR ART DOCUMENTS]] [[PATENT DOCUMENTS]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2016-136838 [[SUMMARY OF THE INVENTION]] [[Problem to be Solved by the Invention]]

[0004] Patent Document 1 describes that the synchronous motor can be controlled not only to avoid general noise frequency bands, but also to avoid device-specific resonance frequencies occurring in the synchronous motor system, but no detailed description is given. An electric circuit such as an inverter that drives a synchronous motor includes coils and capacitors, so there is a region where electrical resonance (i.e., so-called LC resonance) occurs, and Patent Document 1 does not provide control that sufficiently takes this point into consideration. For example, if current ripple is not suppressed and electrical resonance occurs in an electric circuit such as an inverter, the current flowing to a battery that supplies electric power to the inverter may fluctuate, which may shorten battery life. On the other hand, suppressing current ripple may also deteriorate power consumption, which is the energy efficiency of the battery.

[0005] The present invention was made against the above circumstances, and its objective is to provide a control device for a synchronous motor that can suppress the deterioration of energy consumption while suppressing the reduction of battery life due to current ripple. [Means for solving the problem]

[0006] The gist of the present invention is a control device for a synchronous motor equipped with a rotor field-fielded with permanent magnets, wherein (a) vector control is performed using an orthogonal vector coordinate system with a d-axis along the direction of the magnetic flux created by the magnetic poles of the rotor and a q-axis electrically 90 degrees ahead in phase with respect to the d-axis, and (b) if any of the 6nth electrical forcing forces (where n is a natural number) exceeds a predetermined allowable value and the absolute value of the difference between the frequency of the 6nth electrical force and the electrical resonant frequency is less than or equal to a predetermined frequency difference, a predetermined feedforward control is performed based on the electrical angle to suppress the current ripple of the synchronous motor, and otherwise the predetermined feedforward control is not performed. [Effects of the Invention]

[0007] According to the control device for a synchronous motor of the present invention, (a) vector control is performed using an orthogonal vector coordinate system with a d-axis aligned with the direction of the magnetic flux created by the magnetic poles of the rotor and a q-axis electrically 90 degrees ahead in phase with respect to the d-axis, and (b) if any of the 6nth order (n is a natural number) electrical forcing exceeds a predetermined allowable value and the absolute value of the difference between the frequency of the 6nth order electrical forcing and the electrical resonant frequency is less than or equal to a predetermined frequency difference, a predetermined feedforward control based on the electrical angle is performed to suppress the current ripple of the synchronous motor, and otherwise the predetermined feedforward control is not performed. When the predetermined feedforward control to suppress current ripple is performed, the occurrence of electrical resonance in electrical circuits such as inverters that drive the synchronous motor is suppressed, fluctuations in the current flowing to the battery that supplies power to the inverter are suppressed, and a decrease in battery life is suppressed. On the other hand, when the predetermined feedforward control is performed, the battery's energy efficiency deteriorates. In this invention, a predetermined feedforward control to suppress current ripple in a synchronous motor is performed only when any of the 6n-th order electrical forcing forces exceeds a predetermined allowable value and the absolute value of the difference between the frequency of the 6n-th order electrical force and the electrical resonant frequency is less than or equal to a predetermined frequency difference. This suppresses the deterioration of energy efficiency while also suppressing the reduction in battery life due to current ripple. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the schematic configuration of a vehicle equipped with the electronic control device according to Example 1. [Figure 2] This is an example of a flowchart illustrating the control operation of an electronic control unit. [Figure 3] (a) is an example of a forcing map used in step S10 of the flowchart in Figure 2, and (b) is a diagram illustrating an example of a current ripple suppression region within the drivable range of the electric motor 20, where the determination in step S30 is YES. [Figure 4] Figure 2 shows an example of a time chart when the control operation shown in the flowchart is performed. [Figure 5]This is an example of a flowchart illustrating the control operation of the electronic control device according to Example 2. [Figure 6] Figure 5 illustrates the non-applicable region of the high-frequency FF term in step S130 of the flowchart. [Modes for carrying out the invention]

[0009] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. Unless otherwise specified, the drawings in each embodiment have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily depicted accurately. [Examples]

[0010] Figure 1 is a diagram illustrating the schematic configuration of a vehicle 10 equipped with an electronic control device 90 of a synchronous motor 20 (hereinafter simply referred to as "motor 20") according to Embodiment 1. The reference numerals in parentheses in Figure 1 refer to those of Embodiment 2, which will be described later.

[0011] Vehicle 10 is, for example, an electric vehicle or a hybrid vehicle. The electric motor 20 is, for example, a power source for driving vehicle 10, and is a permanent magnet type motor generator having at least the electric motor function among the electric motor function and generator function. The electric motor 20 is a well-known three-phase synchronous motor comprising, for example, a stator 22 and a rotor 24 field-magnetized with permanent magnets 24m. In this embodiment, the rotor 24 has "8" poles and "4" pole pairs. "Number of pole pairs" refers to the number of pairs of magnetic poles in the circumferential direction of the rotor 24. The electric motor 20 is rotationally driven via an inverter 30 by power stored in a battery 40. The inverter 30 is a well-known inverter composed of switching elements. When the electric motor 20 is in operation, the inverter 30 generates three-phase alternating current of U-phase, V-phase, and W-phase. The inverter 30 is controlled by an electronic control device 90.

[0012] The electronic control unit 90 is configured to include, for example, a so-called microcomputer, and controls the inverter 30 by performing signal processing according to a pre-stored program. The electronic control unit 90 corresponds to the "control device" in the present invention.

[0013] The electronic control unit 90 receives various signals based on values ​​detected by various sensors (for example, current sensor 50, rotational speed sensor 52, accelerator pedal position sensor 80, vehicle speed sensor 82, etc.). These signals include, for example, the drive current Img [A] of the electric motor 20, the motor rotational speed Nmg [rpm] which is the rotational speed of the electric motor 20, the rotation angle θmg [rad] which represents the rotational position of the rotor 24 of the electric motor 20, the accelerator pedal position θacc [%] which represents the amount of accelerator operation by the driver, and the vehicle speed V [km / h]. The rotational speed sensor 52 is a resolver that can detect the phase representing the rotational position of the rotor 24 of the electric motor 20, that is, it can detect the rotation angle θmg and the electric motor rotational speed Nmg. Once the rotation angle θmg (mechanical angle) is determined, the electrical angle θe [rad] of the electric motor 20 is determined.

[0014] The electronic control unit 90 outputs a motor control signal Smg to the inverter 30 to control the driving state of the motor 20. The electronic control unit 90 performs, for example, pulse width modulation control by turning the switching elements of the inverter 30 on and off.

[0015] Figure 2 is an example of a flowchart illustrating the control operation of the electronic control unit 90. The flowchart in Figure 2 is executed repeatedly at predetermined control cycles, for example, while the vehicle is in motion. Figure 3 shows (a) an example of a forcing force map used in step S10 (the step is omitted hereafter) in the flowchart of Figure 2, and (b) an example of a current ripple suppression region within the drivable range of the electric motor 20, where the determination in S30 is YES. The electronic control unit 90 performs vector control using an orthogonal vector coordinate system with a d-axis along the direction of the magnetic flux created by the magnetic poles of the rotor 24 and a q-axis electrically advanced by 90 degrees relative to the d-axis. Vector control includes well-known feedback control.

[0016] First, in S10, a predetermined electrical 6n-th order (where n is a natural number) forcing force F[N·m] is estimated. The "predetermined electrical 6n-th order" refers to an order that has been experimentally or design-defined in advance, assuming that the forcing force F described later may exceed a predetermined allowable value F_jdg among the natural number n. The forcing force F is estimated, for example, by applying the actual torque command value Tcom to a forcing force map, which is a predetermined experimental or design-defined relationship between the torque command value Tcom[N·m] and the forcing force F. The "forcing force F" is an electrical resonance forcing force, and as will be described later, it increases as the torque command value Tcom increases. Since the command value of the drive current increases or decreases in accordance with the increase or decrease of the torque command value Tcom, the torque command value Tcom and the command value of the drive current are synonymous. The target value of the drive torque, the required drive torque Trdem[N·m], is determined, for example, by the accelerator opening θacc and the vehicle speed V. The torque command value Tcom is determined based on the required drive torque Trdem. In accordance with this torque command value Tcom, the d-axis current command value id_com[A] and the q-axis current command value iq_com[A] are set, respectively. As shown in Figure 3(a), the forcing force map has a relationship in which the forcing force F increases as the torque command value Tcom increases. After the execution of S10, in S20, the predetermined 6n-th order electrical frequencies f[Hz] are calculated. For example, the frequency f is calculated by the following equation (1). f=Nmg×logarithm of pole pairs×6n / 60 ··· (1)

[0017] After execution of S20, in S30, it is determined whether the excitation force F exceeds a predetermined allowable value F_jdg at any of the predetermined 6n-th electrical order, and whether the absolute value of the difference between the frequency f and the resonance frequency fr[Hz], |Δf|(=|f-fr|), is equal to or less than a predetermined frequency difference Δf_jdg. The resonance frequency fr is an electrical resonance frequency that is predetermined by design based on the circuit constants of coils and capacitors in an electric circuit such as the inverter 30 that drives the electric motor 20. The predetermined frequency difference Δf_jdg is a predetermined frequency difference that is predetermined experimentally or by design, at which resonance at the resonance frequency fr occurs. For example, when the electric motor 20 is driven within the current ripple suppression region shown in FIG. 3(b), the determination in S30 is YES. FIG. 3(b) shows an example where when the electric motor rotation speed Nmg is in the range of speed values 0 to N1, the determination in S30 is YES due to the 6-th electrical order excitation force F; when the electric motor rotation speed Nmg is in the range of speed values N1 to N2, the determination in S30 is YES due to the 12-th electrical order excitation force F; and when the electric motor rotation speed Nmg is in the range of speed values N2 to N3, the determination in S30 is YES due to the 18-th electrical order excitation force F. When the electric motor rotation speed Nmg is in the range of speed values N1 to N2, compared to the range of speed values 0 to N1 and the range of speed values N2 to N3, the current ripple suppression region is formed even when the torque command value Tcom is relatively low. This is because, in the example of FIG. 3(b), the influence of the 12-th electrical order excitation force F is greater compared to the 6-th and 18-th electrical orders.

[0018] If the result of S30 is YES, in S40 the ripple suppression check is turned ON and the flag FLG is set to "1". If the result of S30 is NO, in S42 the ripple suppression check is turned OFF and the flag FLG is set to "0". After the execution of S40 and S42, in both cases, in S50 it is determined whether the flag FLG is "0" and the reflection rate α is "0". The reflection rate α is a coefficient to prevent the d-axis high-frequency FF term Vd_FF_hf[V] and the q-axis high-frequency FF term Vq_FF_hf, which will be described later, from changing abruptly. If the result of S50 is YES, both the d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf are set to zero. If the result of S50 is NO, in S54 the d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf are calculated. In this specification, "FF term" refers to a feedforward term. The d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf are feedforward terms set in the voltage command values ​​on the d-axis and q-axis, respectively, to suppress harmonic components, i.e., to suppress current ripple. The d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf are calculated, for example, by applying the actual electrical angle θe to the high-frequency FF term map for current ripple suppression. The high-frequency FF term map for current ripple suppression is a predetermined relationship between the electrical angle θe and the d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf, determined by experiment, analysis, or machine learning, in order to suppress current ripple. In S80, described later, when the d-axis FF term Vd_FF and the q-axis FF term Vq_FF are calculated, if the product of the d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf is multiplied by the reflection rate α, then the "predetermined feedforward control" in this invention is executed in S90.

[0019] After execution of S54, in S60, it is determined whether the flag FLG is "1". If the determination in S60 is YES, in S62, the reflection rate α is increased by a predetermined value, and in S64, it is determined whether the reflection rate α exceeds "1". If the determination in S64 is YES, in S66, the reflection rate α is set to "1". If the determination in S60 is NO, in S72, the reflection rate α is decreased by a predetermined value, and in S74, it is determined whether the reflection rate α is less than "0". If the determination in S74 is YES, in S76, the reflection rate α is set to "0". The "predetermined value" is a value predetermined experimentally or by design such that the uncomfortable feeling perceived by the driver due to increase and decrease of the reflection rate α falls within an allowable range. In S62 to S66 and S72 to S76, the reflection rate α is increased or decreased within a range that does not exceed the predetermined value for each control cycle. That is, a sudden change in the reflection rate α is avoided.

[0020] After execution of S52, when the determination in S64 is NO, after execution of S66, when the determination in S74 is NO, and after execution of S76, in all cases in S80, a d-axis feedforward term Vd_FF and a q-axis feedforward term Vq_FF are calculated. The d-axis feedforward term Vd_FF is calculated as the sum of the normal d-axis feedforward term Vd_FF_gen [V] and the product of the high-frequency d-axis feedforward term Vd_FF_hf multiplied by the reflection rate α {=Vd_FF_gen+Vd_FF_hf×α}. The q-axis feedforward term Vq_FF is calculated as the sum of the normal q-axis feedforward term Vq_FF_gen [V] and the product of the high-frequency q-axis feedforward term Vq_FF_hf multiplied by the reflection rate α {=Vq_FF_gen+Vq_FF_hf×α}. The d-axis feedforward term Vd_FF and the q-axis feedforward term Vq_FF are feedforward terms set to voltage command values on the d-axis and the q-axis, respectively. The normal d-axis feedforward term Vd_FF_gen and the normal q-axis feedforward term Vq_FF_gen are feedforward terms set to voltage command values on the d-axis and the q-axis, respectively, which are determined based on the torque command value Tcom and the motor rotation speed Nmg.

[0021] After the execution of S80, in S82, the d-axis FB term Vd_FB[V] and the q-axis FB term Vq_FB[V] are calculated. In this specification, "FB term" refers to a feedback term. The d-axis FB term Vd_FB and the q-axis FB term Vq_FB are feedback terms set for the voltage command values ​​in the d-axis and q-axis, respectively. The d-axis FB term Vd_FB is calculated based on the value obtained by multiplying the difference Δid (=id_com-id_real) between the d-axis current command value id_com and the actual d-axis current id_real[A] by the PI gain. The q-axis FB term Vq_FB is calculated based on the value obtained by multiplying the difference Δiq (=iq_com-iq_real) between the q-axis current command value iq_com and the actual q-axis current iq_real[A] by the PI gain. The PI gain is the gain due to the well-known proportional and integral terms. The d-axis actual current id_real and the q-axis actual current iq_real are calculated by transforming the drive current Img to the d-axis and q-axis coordinates. After the execution of S82, in S84, the d-axis voltage command value Vd_com and the q-axis voltage command value Vq_com are calculated. The d-axis voltage command value Vd_com is calculated as the sum of the d-axis FF term Vd_FF and the d-axis FB term Vd_FB. The q-axis voltage command value Vq_com is calculated as the sum of the q-axis FF term Vq_FF and the q-axis FB term Vq_FB. After the execution of S84, in S90, the d-axis voltage command value Vd_com and the q-axis voltage command value Vq_com are used as voltage command values ​​and transformed to the U-phase, V-phase, and W-phase coordinates to execute switching control of the inverter 30. After the execution of S90, the program returns.

[0022] Figure 4 is an example of a time chart when the control operation shown in the flowchart of Figure 2 is performed. The horizontal axis of Figure 4 represents time t [s].

[0023] Prior to time t1, the state in S30 where the judgment is NO (i.e., FLG = "0") is maintained. At time t1, the state in S30 where the judgment is NO changes to the state where it is YES. As a result, the flag FLG is set to "1", and in S62, current ripple suppression control is executed as the applicable range for the reflection rate increase, where the reflection rate α is gradually increased. At time t2 (>t1), the reflection rate α reaches "1", and current ripple suppression control with a reflection rate of "1" is executed. At time t3 (>t2), the state in S30 where the judgment is NO changes. As a result, the flag FLG is set to "0", and in S72, current ripple suppression control is executed as the applicable range for the reflection rate decrease, where the reflection rate α is gradually decreased. At time t4 (>t3), the reflection rate α reaches "0", and current ripple suppression control is not executed.

[0024] According to this embodiment, (a) vector control is performed using an orthogonal vector coordinate system with a d-axis aligned with the direction of the magnetic flux created by the magnetic poles of the rotor 24 and a q-axis electrically 90 degrees ahead in phase with respect to the d-axis. (b) If any of the 6n-th order (n is a natural number) electrical forcing forces F exceed a predetermined allowable value F_jdg and the absolute value |Δf| of the difference between the 6n-th order electrical frequency f and the electrical resonant frequency fr is less than or equal to a predetermined frequency difference Δf_jdg, a predetermined feedforward control based on the electrical angle θe is performed to suppress the current ripple of the motor 20. Otherwise, the predetermined feedforward control is not performed. When the predetermined feedforward control to suppress current ripple is performed, the occurrence of electrical resonance in electrical circuits such as the inverter 30 is suppressed, fluctuations in the current flowing to the battery 40 that supplies power to the inverter 30 are suppressed, and a decrease in battery life is suppressed. On the other hand, when the predetermined feedforward control is performed, the power consumption of the battery 40 deteriorates. In this embodiment, predetermined feedforward control is performed only when any of the 6n-th order electrical forcing forces F exceeds a predetermined allowable value F_jdg and the absolute value |Δf| of the difference between the 6n-th order electrical frequency f and the electrical resonant frequency fr is less than or equal to a predetermined frequency difference Δf_jdg. This suppresses the deterioration of energy efficiency while also suppressing the reduction in battery life due to current ripple. [Examples]

[0025] Figure 5 is an example of a flowchart illustrating the control operation of the electronic control device 190 according to Embodiment 2. Figure 6 is a diagram illustrating the non-applicable region of the high-frequency FF term (d-axis high-frequency FF term Vd_FF_hf and q-axis high-frequency FF term Vq_FF_hf) in S130 of the flowchart in Figure 5. The electronic control device 190 according to this embodiment has substantially the same configuration as the electronic control device 90 according to Embodiment 1 described above, but the control operation is different. Therefore, in this embodiment, the explanation will focus on the parts that differ from Embodiment 1, and parts that are substantially common in function with Embodiment 1 will be given the same reference numerals and their explanations will be omitted as appropriate.

[0026] The flowchart shown in Figure 5 is substantially the same as the flowchart in Figure 2 in the previously described Embodiment 1. First, in S130, it is determined whether or not the high-frequency FF term is applicable. Whether or not the high-frequency FF term is applicable is determined, for example, using a high-frequency FF term application map. As shown in Figure 6, for example, the high-frequency FF term application map is region A, which is the non-applicable region of the high-frequency FF term, when the motor rotation speed Nmg is less than or equal to a predetermined first speed determination value Nmg_jdg1 and the torque command value Tcom is less than or equal to a predetermined command determination value Tcom_jdg. The predetermined command determination value Tcom_jdg and the predetermined first speed determination value Nmg_jdg1 are predetermined determination values ​​that are experimentally or design-wise determined in advance, assuming that drivability does not deteriorate even without applying the high-frequency FF term and that the voltage command value can track the current command value using only the FB term. Preferably, as shown in Figure 6, when the motor rotation speed Nmg exceeds a predetermined first speed determination value Nmg_jdg1 and is less than or equal to a predetermined second speed determination value Nmg_jdg2 (>Nmg_jdg1), and the torque command value Tcom is less than or equal to a predetermined command determination value Tcom_jdg, the region B is the applicable region for the high-frequency FF term. Within the drivable range of the motor 20, the region that is neither region A nor region B is region C. In region A, the reflection rate α is steadily set to "0", in region B, the reflection rate α is steadily set to "1", and in region C, torque ripple suppression control is not performed. In other words, in region A, torque ripple suppression control is performed using FB terms (d-axis FB term Vd_FB and q-axis FB term Vq_FB) and normal FF terms (d-axis normal FF term Vd_FF_gen and q-axis normal FF term Vq_FF_gen), and in region B, torque ripple suppression control is performed by adding high-frequency FF terms (d-axis high-frequency FF term Vd_FF_hf and q-axis high-frequency FF term Vq_FF_hf) to these. Note that in region A, torque ripple suppression control may be performed using only FB terms (d-axis FB term Vd_FB and q-axis FB term Vq_FB).

[0027] To suppress torque ripple as a countermeasure against vehicle vibration and noise, control that adjusts the current command value is commonly performed. In this case, it is necessary to set the voltage command value so that it can follow the current command value. To make it easier for the voltage command value to follow the current command value, it is conceivable to add an FF term (feedforward term) to the FB term (feedback term). However, the ratio of the high-frequency FF term among the FF terms increases as the rotational speed of the motor 20 decreases. If the motor rotational speed Nmg changes abruptly in the low-speed range of the motor 20, a discrepancy occurs between the motor rotational speed Nmg recognized by the electronic control device 190 based on the sensor detection value and the actual motor rotational speed Nmg, and the high-frequency FF term is not calculated correctly. On the other hand, even if the motor rotational speed Nmg changes abruptly in the low-speed range, drivability does not deteriorate, and the voltage command value can be made to follow the current command value with only the FB term.

[0028] If the determination in S130 is YES, S140 is executed; if the determination in S130 is NO, S142 is executed. Here, the ripple suppression determination in S140 and S142 in this embodiment is a determination of whether or not to suppress torque ripple. In addition, the d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf in S154 and S152 are calculated, for example, by applying the actual electrical angle θe to the high-frequency FF term map for torque ripple suppression. The high-frequency FF term map for torque ripple suppression is a predetermined relationship between the electrical angle θe and the d-axis high-frequency FF term Vd_FF_hf and the q-axis high-frequency FF term Vq_FF_hf, determined by experiment, analysis, or machine learning, in order to suppress torque ripple.

[0029] According to this embodiment, (a) vector control is performed using an orthogonal vector coordinate system with respect to the d axis and q axis, and (b) when the motor rotation speed Nmg is less than or equal to a predetermined first speed determination value Nmg_jdg1, a predetermined feedforward control based on the electrical angle θe is not performed in order to suppress torque ripple of the motor 20. As a result, torque ripple is suppressed while deterioration of drivability is suppressed.

[0030] The above-described examples are embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, without departing from its spirit. [Explanation of Symbols]

[0031] 20: Synchronous motor, 24: Rotor, 24m: Permanent magnet, 90: Electronic control unit (control device), f: Frequency, fr: Resonant frequency, F: Forcing force, F_jdg: Prescribed allowable value, Nmg: Motor rotational speed (rotational speed of synchronous motor), Tcom: Torque command value, |Δf|: Absolute value of difference (absolute value of the difference between the 6th order electrical frequency and the electrical resonant frequency), Δf_jdg: Prescribed frequency difference, θe: Electrical angle

Claims

[Claim 1] A control device for a synchronous motor equipped with a rotor field-fielded with permanent magnets, Vector control is performed using an orthogonal vector coordinate system with a d-axis aligned with the direction of the magnetic flux created by the magnetic poles of the rotor and a q-axis electrically 90 degrees ahead in phase with respect to the d-axis. If any of the 6nth electrical forcing forces (where n is a natural number) exceeds a predetermined allowable value and the absolute value of the difference between the frequency of the 6nth electrical forcing force and the electrical resonant frequency is less than or equal to a predetermined frequency difference, a predetermined feedforward control based on the electrical angle is executed to suppress the current ripple of the synchronous motor; otherwise, the predetermined feedforward control is not executed. A control device for a synchronous motor, characterized by the following features.

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