CN111713004A

CN111713004A - Motor control system and power steering system

Info

Publication number: CN111713004A
Application number: CN201980012985.0A
Authority: CN
Inventors: 远藤修司; 馆胁得次; 上田智哉; 绵引正伦; 森智也
Original assignee: Nidec Corp; Nidec Elesys Corp
Current assignee: Nidec Corp
Priority date: 2018-02-20
Filing date: 2019-02-13
Publication date: 2020-09-25
Anticipated expiration: 2039-02-13
Also published as: WO2019163589A1; JPWO2019163589A1; CN111713004B

Abstract

The motor control system includes: an inverter that drives the motor; and a control calculation unit that performs feedback control on the inverter, the control calculation unit including: a voltage control calculation unit that calculates a voltage command value indicating a voltage applied from the inverter to the motor based on a current deviation between the current command value and the actual current detection value; and a torque ripple compensation calculation unit that adds a compensation value for compensating for torque ripple in the motor to a signal value on a downstream side of a signal flow through the voltage control calculation unit, the torque ripple compensation calculation unit including: a phase compensation unit that calculates a compensation value component of the voltage control calculation unit based on an actual angular velocity value indicating an angular velocity of rotation of the motor; and an inverse characteristic calculation processing unit that calculates a compensation value component for compensating for the torque ripple, based on an inverse characteristic of an electrical characteristic of the motor.

Description

Motor control system and power steering system

Technical Field

The present disclosure relates to a motor control system and a power steering system.

Background

Conventionally, as a motor control technique, a method is known in which a control device feedback-controls a motor using a command value. For example, a control device is known that feeds back a current command value that is in an opposite phase to a torque ripple and adds the current command value to a basic command value. In such a configuration, a method is known in which the control device superimposes a current command value of a harmonic component of a current value on a basic command value to compensate for torque ripple (for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 4019842

Disclosure of Invention

Problems to be solved by the invention

However, the feedback control in the conventional structure has the following problems: although it functions efficiently in a frequency domain where the current controller can respond at a sufficiently fast speed, it does not function in a high frequency domain where the response of the current controller lags. In general, the responsiveness of a current controller is designed to a degree that the current controller can respond to a frequency band of a fundamental wave (sine wave) in which a current that is a practical basis can be obtained. In addition, a general torque ripple is a harmonic component of a sine wave of a fundamental current. Therefore, in the current controller designed as described above, the responsiveness of the current controller is insufficient, and torque ripple compensation cannot be sufficiently performed.

Accordingly, it is an object of the present invention to provide a motor control system that achieves low operating noise.

Means for solving the problems

An exemplary motor control system according to the present invention drives a motor having a number of phases n of 3 or more, the motor control system including: an inverter that drives the motor; and a control calculation unit that calculates a current command value indicating a current supplied from the inverter to the motor based on a target current command value supplied as a control target of the motor from outside, and feeds back an actual current detection value indicating a current actually supplied from the inverter to the motor to the current command value to perform feedback control of the inverter, the control calculation unit including: a voltage control calculation unit that calculates a voltage command value indicating a voltage applied from the inverter to the motor, based on a current deviation between the current command value and the actual current detection value; and a torque ripple compensation calculation unit that adds a compensation value that compensates for torque ripple in the motor to a signal value on a downstream side of a signal flow through the voltage control calculation unit, the torque ripple compensation calculation unit including: a phase compensation unit that calculates a compensation value component of the voltage control calculation unit based on an actual angular velocity value indicating an angular velocity of rotation of the motor; and an inverse characteristic calculation processing unit that calculates a compensation value component that compensates for the torque ripple, based on an inverse characteristic of an electrical characteristic of the motor.

An exemplary power steering system of the present invention includes: the motor control system; a motor controlled by the motor control system; and a power steering mechanism driven by the motor.

Effects of the invention

According to the exemplary embodiments of the present invention, a motor control system that realizes low operating sound can be provided.

Drawings

Fig. 1 is a schematic diagram of a motor control system of a first embodiment.

Fig. 2 is a schematic diagram of a control arithmetic unit according to the first embodiment.

Fig. 3 is a plan view of the first motor of the present embodiment.

Fig. 4 is a plan view of the second motor of the present embodiment.

Fig. 5 is a schematic view of the electric power steering apparatus.

Fig. 6 is a conceptual diagram of a motor unit having a traction motor.

Fig. 7 is a side schematic view of the motor unit.

Detailed Description

Hereinafter, embodiments of a controller, a motor control system having the controller, and an electric power steering system having the motor control system according to the present disclosure will be described in detail with reference to the accompanying drawings. However, in order to avoid unnecessarily long descriptions below, it is easy for those skilled in the art to understand that the detailed descriptions above may be omitted. For example, detailed descriptions of known matters and repetitive descriptions of substantially the same structure may be omitted.

< first embodiment >

A motor control system according to a first embodiment will be described, in which the output of the torque ripple compensation calculation unit is a "voltage value". The motor control system according to the first embodiment is a control system that controls a 3-phase brushless motor, for example. Hereinafter, for convenience, a case where the d-axis current Id and the q-axis current Iq are positive with each other, that is, a case where the rotation is in one direction will be described. In the motor control system of the present embodiment, torque ripple can be mainly reduced.

Generally, the q-axis current Iq has a larger influence than the d-axis current Id with respect to the generation of torque in the 3-phase motor. Therefore, to reduce the torque ripple, it is preferable to mainly control the q-axis current Iq to apply the present control system. In addition, even in the case of a control system that reduces Back Electromotive Force (BEMF), feedback control can be performed by the same configuration as the present invention. That is, in the control method of the present invention, only the q-axis current may be used as the command value, or both the q-axis current Iq and the d-axis current Id may be used as the command value. In this specification, the description of the control method related to the d-axis current Id is omitted.

Fig. 1 is a schematic diagram of a motor control system according to a first embodiment, and fig. 2 is a schematic diagram of a control arithmetic unit according to the first embodiment. As shown in fig. 1, the motor control system 5 includes a motor rotation angle sensor 51, an inverter 52, and a control calculation unit 53. The control arithmetic unit 53 functions as a so-called current controller. As shown in fig. 2, the control arithmetic unit 53 includes a torque ripple compensation arithmetic unit 531, a current limit arithmetic unit 532, a voltage control arithmetic unit 533, an induced voltage compensation arithmetic unit 534, a 2-axis/3-phase conversion unit 535, a dead time compensation arithmetic unit 536, and a PWM control arithmetic unit 537.

The motor control system 5 controls the motor 1 via the inverter 52. The motor 1 includes a rotor 3, a stator 2, and a motor rotation angle sensor 51. The motor rotation angle sensor 51 detects the rotation angle of the rotor 3 of the motor 1. The detected rotation angle of the rotor is expressed in arbitrary angular units, and is appropriately converted from a mechanical angle to a motor electrical angle θ or from the motor electrical angle θ to a mechanical angle. The relationship between the mechanical angle and the motor electrical angle θ is expressed by a relational expression of the motor electrical angle θ ═ mechanical angle × (number of magnetic poles ÷ 2). Further, instead of the rotation angle sensor, an angular velocity sensor, for example, may be provided as a sensor for detecting the rotation of the motor.

The motor control system 5 of the present embodiment performs control of feeding back a current value (actual q-axis current value IQR) flowing through the inverter 52. Although not shown, the motor control system 5 may also perform known arithmetic processing such as field weakening control. The motor control system 5 can suppress torque variation of the motor 1 by performing field weakening control.

The target q-axis current Iq _ target is input to the motor control system 5 from the outside. The increase or decrease of the motor output is externally instructed by the increase or decrease of the target q-axis current Iq _ target. The present motor control system 5 current-limits the input target q-axis current Iq _ target. The current limit is processed by the current limit calculation unit 532. The current limit calculation unit 532 receives an input of the target q-axis current Iq _ target and performs adaptive control, thereby limiting the target q-axis current Iq _ target (output value) to a predetermined current value or less.

When the target q-axis current Iq _ target is not limited to exceed the predetermined current value, the motor applied voltage may be saturated as a result of the processing described later. When the motor applied voltage is saturated in this way, there is no room for adding the compensation current for suppressing the motor torque variation to the target q-axis current Iq _ target. As a result, the following problems occur: the torque fluctuation is increased sharply, and the working sound is generated. In order to avoid this problem, it is effective to limit the target q-axis current Iq _ target by the current limit calculation unit 532 so as to make a margin for the compensation current. The saturation of the motor applied voltage occurs depending on both the motor current and the motor rotation angular velocity. Therefore, the current limit calculation unit 532 of the present embodiment limits the motor current (target q-axis current Iq _ target) using a function having the motor rotation angular velocity as a parameter. By such current limitation, a margin for compensating for torque ripple at ordinary times (when the voltage is not saturated) is secured. Therefore, quiet and smooth rotation of the motor is achieved.

More specifically, the adaptive control of the current limit calculation unit 532 reduces the range using a function having a motor rotation angular velocity as a parameter. This function is a continuous function for the input target q-axis current Iq _ target. That is, the current limit calculation unit 532 does not perform discontinuous limitation such as peak off of the current, but performs continuous range reduction in which the current is limited more greatly as the input current value is larger. The function used for the range reduction in the current limit calculation unit 532 may be a function that exhibits linear reduction or a function that exhibits nonlinear (and continuous) reduction.

The reduction range of the range reduction is such that the reduction range of current value i is reduced so as to satisfy the following inequality.

Vsat＞(Ls+R)i+keω···(1)

Here, Vsat is a saturation voltage, Ls is an inductance of the motor, R is a resistance of the motor, and ke ω is an induced voltage accompanying the rotation of the motor.

In the adaptive control of the current limit calculation unit 532, the limit value of the current based on the range reduction is a limit value corresponding to the battery voltage Vbat when the driving is performed by the battery power supply. The battery power is used in the case where the supply amount of the alternator is insufficient. Since the battery power supply has an internal resistance, the internal resistance changes with the deterioration of the battery power supply, and the effective output voltage changes. Therefore, adaptive control is performed in accordance with the battery voltage Vbat.

The motor control system 5 feeds back an actual q-axis current value IQR flowing in the inverter (or the motor), subtracts the actual q-axis current value IQR from a command value of the q-axis current, and calculates a current deviation IQ _ err of the q-axis current. That is, the present motor control system 5 performs feedback control for calculating the current deviation IQ _ err.

Then, the present motor control system 5 performs voltage control on the current deviation IQ _ err obtained by the feedback control. The voltage control is performed by the voltage control operation unit 533. In the present embodiment, PI control is used as the voltage control. The voltage control is not limited to PI control, and other control methods such as PID control may be employed. In the voltage control operation unit 533, the Q-axis PI control unit 5331 calculates a Q-axis voltage command value VQ1 from the current deviation IQ _ err of the Q-axis current, and adds the Q-axis voltage command value VQ1 to the non-interference element COR _ Q output from the non-interference processing unit 5332 to calculate a Q-axis voltage command value VQ 2. The non-interference element COR _ Q is a current element applied to avoid interference between a d-axis current (voltage) and a Q-axis current (voltage), for example.

Then, the motor control system 5 performs induction voltage compensation on the q-axis voltage command value VQ 2. The induced voltage compensation operation unit 534 performs induced voltage compensation. When the motor is driven, the motor is controlled in consideration of the influence of the induced voltage of the motor in addition to the current flowing through the motor. The induced voltage compensation calculation unit 534 performs advance angle control based on the reciprocal of the induced voltage (BEMF) generated by the motor, and compensates the induced voltage (BEMF).

That is, the induced voltage compensation calculation unit 534 obtains the reciprocal of the induced voltage (BEMF) generated by the motor, and calculates a compensation value for performing compensation of the advance angle of the adjustment voltage (or current) (advance angle compensation) based on the reciprocal. In the present embodiment, the induced voltage compensation arithmetic unit 534 calculates a q-axis voltage command value VQ3 by adding a compensation value for induced voltage compensation to the q-axis voltage command value VQ 2. In addition, if a compensation value based on the inverse of the induced voltage model is used, the compensation value may be subtracted from the q-axis voltage command value VQ2 instead of being added to the compensation value. The compensation value may be added to the voltage value of each phase converted from 2-axis/3-phase.

The motor control system 5 performs torque fluctuation compensation control in accordance with the angular velocity ω. The torque ripple compensation control is processed by the torque ripple compensation arithmetic unit 531. The torque ripple compensation calculation unit 531 includes a phase compensation unit 5311 and an inverse characteristic calculation unit 5312. The torque ripple compensation calculation unit 531 first calculates an adjustment value for advance control for adjusting the phase of the voltage from the angular velocity ω of the rotor in the phase compensation unit 5311. The angular velocity ω is calculated from the rotation angle of the rotor 3 (motor electrical angle θ) detected by the motor rotation angle sensor 51. Then, the torque ripple compensation calculation unit 531 calculates a torque ripple compensation value for suppressing torque ripple by performing calculation based on a transfer function (inverse transfer function) as an inverse characteristic for the plant element p(s) based on the adjustment value in the inverse characteristic calculation unit 5312. The plant element p(s) is the transfer function of the motor and inverter coupling.

Here, the device element p(s) in the first embodiment is expressed by the following equation (2) with the induced voltage ke ω in the voltage equation V ═ Ls + R) i + ke ω regarded as interference. Lq is the q-axis inductance in the motor, and Rq is the q-axis component of the motor's resistance.

[ mathematical formula 1]

Therefore, the inverse transfer function g(s) of the device element p(s) is represented by the following expression (3). T1 is a transfer function of a noise filter disposed at least one of before and after the inverse characteristic arithmetic processing unit 5312 and coupled thereto.

[ mathematical formula 2]

The torque ripple compensation calculation unit 531 calculates a torque ripple compensation value in the inverse characteristic calculation processing unit 5312 based on the inverse transfer function g(s) derived as described above. The obtained torque ripple compensation value is added to the q-axis voltage command value VQ3 output from the induced voltage compensation operation unit 534, and the q-axis voltage command value VQ4 is calculated. By adding the compensation value for the torque ripple to the voltage value, there is an advantage that the arithmetic processing is faster than the case of adding the current value. The inverse transfer function g(s) may be obtained from a transfer function of the device elements p(s) for each product obtained by individual measurement before shipment of the product, or may be obtained from a transfer function of the device elements p(s) obtained by simulation based on design values or the like, for example. Alternatively, as the inverse transfer function g(s), for example, the transfer characteristics of the plant elements p(s) may be measured as a representative value or an average value for the same type of motor 1 and the motor control system 5, and the inverse transfer function g(s) calculated based on the transfer characteristics may be commonly used for the same type of motor 1. Whether in the case of a measurement-based inverse transfer function g(s) or in the case of a calculated inverse transfer function g(s), the decision may be made taking into account certain errors or approximations. Further, the correction may be performed using adaptive control or the like. By adopting the configuration in which the torque ripple compensation value is calculated using the inverse transfer function g(s), there is an advantage that design at the time of manufacturing such as substrate design is simplified.

Then, the motor control system 5 performs 2-axis/3-phase conversion on the q-axis voltage command value VQ 4. The 2-axis/3-phase conversion is performed by the 2-axis/3-phase conversion calculation unit 535 according to the motor electrical angle θ. The 2-axis/3-phase conversion arithmetic unit 535 calculates the corresponding q-axis voltage and d-axis voltage from the q-axis voltage command value VQ3, and converts the q-axis voltage and d-axis voltage into 3-phase voltage command values for U, V, W phases.

Then, the motor control system performs dead time compensation based on the voltage command value for each phase output from the 2-axis/3-phase conversion arithmetic unit 535. The dead time compensation is performed by the dead time compensation operation unit 536. First, in the dead time compensation calculation unit 536, the midpoint modulation unit 5363 performs a calculation based on midpoint modulation in which a harmonic (for example, a third harmonic) that is n times a fundamental wave of a voltage is superimposed. n is a positive integer. By performing the midpoint modulation, the waveform of the voltage approaches a trapezoidal waveform from a sinusoidal waveform. This increases the effective voltage rate of the inverter 52.

Next, the dead time compensation operation unit 536 compensates for the dead time. The above-described processing for the current deviation IQ _ err is performed up to the midpoint modulation section 5363, and the voltage component for reducing the current deviation IQ _ err is calculated. On the other hand, the target q-axis current IQ _ target is input to the target IQ 2-axis/3-phase conversion unit 5362, and the voltage command value corresponding to the target q-axis current IQ _ target is subjected to 2-axis/3-phase conversion. That is, the target IQ 2-axis/3-phase conversion section 5362 calculates a q-axis voltage and a d-axis voltage corresponding to the target q-axis current IQ _ target, and converts them into U, V, W-phase 3-phase voltage command values for the respective phases.

In the 2-axis/3-phase conversion by the target IQ 2-axis/3-phase conversion section 5362, the motor electrical angle is used for the calculation, as in the 2-axis/3-phase conversion by the 2-axis/3-phase conversion calculation section 535. However, in the motor control system 5 of the present embodiment, the motor electrical angle θ 2 obtained by phase-compensating the motor electrical angle θ detected by the sensor is used as the motor electrical angle input to the target IQ 2 axis/3 phase conversion unit 5362. The phase compensation is performed by the correction phase compensation section 5361, and the phase offset of the voltage caused by the motor rotation is compensated by the phase compensation.

Finally, the motor control system performs PWM control based on the voltage command value output from the dead time compensation arithmetic unit 536. The PWM control command value is calculated by a PWM control calculation unit 537. The PWM control calculation unit 537 controls the voltage of the inverter 52 based on the calculated command value. By this PWM control, a current corresponding to the current command value flows to the motor 1. In addition, as described above, the actual q-axis current value IQR flowing in the inverter 52 is fed back.

In the present system, the above-described processing such as PI control, induced voltage compensation, 2-axis/3-phase conversion, dead time compensation, PWM control, and the like is not limited to the above-described example, and known techniques may be applied. In the present system, these compensation and control may not be performed, if necessary.

< other embodiments >

Here, a motor that can be controlled by the above-described embodiment will be described in outline. Fig. 3 is a plan view of the first motor of the present embodiment, and fig. 4 is a plan view of the second motor of the present embodiment. The motor 1 shown in fig. 3 and 4 has a stator 2 and a rotor 3. As shown in fig. 3 and 4, the motor 1 is of an inner rotor configuration. In addition, as the motor 1, an outer rotor structure may be adopted in addition to the inner rotor structure. The first motor 1 shown in fig. 3 is an IPM (Interior Permanent Magnet) motor, and the second motor 1 shown in fig. 4 is an SPM (Surface Permanent Magnet) motor.

The stator 2 has a cylindrical outer shape extending in the axial direction. The stator 2 is disposed radially outward of the rotor 3 with a predetermined gap from the rotor 3. The stator 2 includes a stator core 21, an insulator 22, and a coil 23. The stator core 21 is a cylindrical member extending in the axial direction. The stator core 21 is formed by laminating a plurality of magnetic steel plates in the axial direction. The stator core 21 has a core back 21a and teeth (not shown). The core back 21a is a circular ring-shaped portion. The teeth extend radially inward from the inner circumferential surface of the core back 21 a. The teeth are arranged at predetermined intervals in the circumferential direction. In addition, the gap between adjacent teeth is referred to as a slot S. In the motor 1 shown in fig. 3 and 4, for example, 12 grooves S are provided.

The rotor 3 has a cylindrical outer shape extending in the axial direction. The rotor 3 is disposed radially inward of the stator 2 with a predetermined gap from the stator 2. The rotor 3 includes a shaft 31, a rotor core 40, and a magnet 32. The rotor 3 rotates about a shaft 31 extending in the vertical direction (direction perpendicular to the paper surface of fig. 3 and 4). The rotor core 40 is a cylindrical member extending in the axial direction. The shaft 31 is inserted into a hole 41d located at a radially central portion of the rotor core 40. The rotor core 40 is formed by laminating a plurality of magnetic steel plates in the axial direction. The magnet 32 is disposed inside the rotor core 40 in the first motor 1 shown in fig. 3, and is attached to the surface of the rotor core 40 in the second motor 1 shown in fig. 4. A plurality of magnets 32 are arranged at predetermined intervals in the circumferential direction. In the motor 1 shown in fig. 3 and 4, for example, 8 magnets 32 are provided. That is, in the motor 1 shown in fig. 3 and 4, the number of poles P is 8.

The magnetic characteristics of the motor are different depending on the number of poles P and the number of slots S. Here, the factors that generate the operating sound include radial force and torque ripple. In the case of the motor of 8P12S in which the number of poles P is 8 and the number of slots S is 12, the radial force, which is the radial component of the electromagnetic force generated between the rotor and the stator, cancels each other, and thus torque ripple becomes a cause of a main operating sound. That is, the operating sound of the motor of 8P12S is efficiently reduced by compensating only the torque ripple by the above-described motor control system. Accordingly, the motor control system of the present invention is particularly useful in motors of 8P 12S.

The motor control system of the present invention is particularly useful in SPM motors because the cancellation of radial forces is particularly effective in SPM motors. More specifically, in the SPM motor, reluctance torque is not generated, and only magnet torque acts. Therefore, by adopting the present invention, only the magnet torque is compensated, thereby achieving vibration reduction. Conversely, the cancellation of the radial force is not limited to the effect produced in the SPM motor and the motor of 8P12S, but is also produced in the IPM motor or, for example, the 10P12S motor, and therefore the motor control system of the present invention is also useful in the IPM motor or, for example, the 10P12S motor.

Next, an outline of the electric power steering apparatus will be explained. As shown in fig. 5, in the present embodiment, a column-type electric power steering apparatus is exemplified. The electric power steering apparatus 9 is mounted on a steering mechanism of a wheel of an automobile. The electric power steering device 9 is a column type power steering device that directly reduces a steering force by the power of the motor 1. The electric power steering apparatus 9 includes a motor 1, a steering shaft 914, and an axle 913.

The steering shaft 914 transmits an input from a steering wheel 911 to an axle 913 having wheels 912. The power of the motor 1 is transmitted to the axle 913 via the ball screw. The motor 1 employed in the column-type electric power steering apparatus 9 is disposed inside an engine room (not shown). In addition, the electric power steering apparatus 9 shown in fig. 5 is of a column type as an example, but the power steering apparatus of the present invention may be of a rack type.

Here, in an application requiring low torque ripple and low operating sound like the electric power steering device 9, the following effects are provided: by controlling the motor 1 by the motor control system 5 described above, a compromise between low torque ripple and low operating sound is achieved. The reason for this is that torque ripple having a frequency exceeding the response of current control is compensated for by compensating the response of the current controller without using a high-pass filter for amplifying noise, thereby producing an effect of torque ripple compensation. Therefore, the present invention is particularly useful in a power steering apparatus.

The present invention is also useful for applications other than power steering devices. The present invention is useful for motors requiring a reduction in operating noise, such as a traction motor (a motor for running), a motor for a compressor, and a motor for an oil pump.

Hereinafter, a motor unit having a traction motor will be described.

In the following description, unless otherwise specified, a direction parallel to the motor axis J2 of the motor 102 is simply referred to as "axial direction", a radial direction with the motor axis J2 as a center is simply referred to as "radial direction", and a circumferential direction with the motor axis J2 as a center, that is, a direction around the motor axis J2 is simply referred to as "circumferential direction". However, the "parallel direction" also includes a substantially parallel direction. Fig. 6 is a conceptual diagram of the motor unit 100 having the traction motor, and fig. 7 is a side schematic diagram of the motor unit 100.

The motor unit 100 is mounted on a vehicle having a motor as a power source, such as a Hybrid Electric Vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an Electric Vehicle (EV), and is used as a power source. The motor unit 100 of the present embodiment includes a motor (main motor) 102, a gear portion 103, a housing 106, and a motor control system 5.

As shown in fig. 6, the motor 102 includes a rotor 120 that rotates about a motor axis J2 extending in the horizontal direction, and a stator 130 located radially outward of the rotor 120. A housing space 180 for housing the motor 102 and the gear portion 103 is provided inside the housing 106. The housing space 180 is divided into a motor chamber 181 housing the motor 102 and a gear chamber 182 housing the gear portion 103.

The motor 102 is housed in a motor chamber 181 of the housing 106. The motor 102 has a rotor 120 and a stator 130 located radially outward of the rotor 120. The motor 102 is an inner rotor type motor, and includes a stator 130 and a rotor 120 rotatably disposed inside the stator 130.

The rotor 120 is rotated by supplying electric power from a battery, not shown, to the stator 130 via the motor control system 5. The rotor 120 includes a shaft (motor shaft) 121, a rotor core 124, and a rotor magnet (not shown). The rotor 120 (i.e., the shaft 121, the rotor core 124, and the rotor magnet) rotates about a motor axis J2 extending in the horizontal direction. The torque of the rotor 120 is transmitted to the gear portion 103.

The shaft 121 extends with a motor axis J2 extending in the horizontal direction and the width direction of the vehicle as the center. The shaft 121 rotates about a motor axis J2.

The shaft 121 extends across the motor chamber 181 and the gear chamber 182 of the housing 106. One end portion of the shaft 121 protrudes to the gear chamber 182 side. A first gear 141 is fixed to an end of the shaft 121 protruding into the gear chamber 182.

The rotor core 124 is formed by laminating silicon steel plates (magnetic steel plates). The rotor core 124 is a cylindrical body extending in the axial direction. A plurality of rotor magnets are fixed to the rotor core 124.

The stator 130 surrounds the rotor 120 from the radially outer side. In fig. 11, a stator 130 has a stator core 132 and a coil 131. The stator 130 is held by the housing 106. Although not shown, the stator core 132 has a plurality of magnetic pole teeth radially inward from the inner circumferential surface of the annular yoke. A coil wire (not shown) is wound between the magnetic pole teeth to form a coil 31.

The gear portion 103 is housed in a gear chamber 182 of the housing 106. The gear portion 103 is connected to the shaft 121 on one axial side of the motor axis J2. The gear portion 103 has a reduction gear 104 and a differential gear 105. The torque output from the motor 102 is transmitted to the differential device 105 via the reduction gear 104.

The reduction gear 104 is connected to the rotor 120 of the motor 102. The reduction gear 104 has the following functions: the rotation speed of the motor 102 is reduced, and the torque output from the motor 102 is increased according to the reduction ratio. The reduction gear 104 transmits the torque output from the motor 102 to the differential 105.

The reduction gear 104 has a first gear (intermediate drive gear) 141, a second gear (intermediate gear) 142, a third gear (final drive gear) 143, and an intermediate shaft 145. The torque output from the motor 102 is transmitted to a ring gear (gear) 151 of the differential device 105 via a shaft 121 of the motor 102, a first gear 141, a second gear 142, an intermediate shaft 145, and a third gear 143.

The differential device 105 is connected to the motor 102 via the reduction gear 104. The differential device 105 is a device for transmitting the torque output from the motor 102 to the wheels of the vehicle. The differential device 105 has the following functions: the speed difference of the left and right wheels is absorbed when the vehicle turns, and the torque is transmitted to the axles 155 of the left and right wheels.

The motor control system 5 is electrically connected to the motor 102. The motor control system 5 supplies electric power to the motor 102 through an inverter. The motor control system 5 controls the current supplied to the motor 2. By compensating for the torque fluctuation with the motor control system 5, the operating sound of the motor 102 is reduced.

While the embodiment and the modification of the present invention have been described above, the configurations and combinations thereof in the embodiment and the modification are merely examples, and addition, omission, replacement, and other modifications of the configurations can be made within the scope not departing from the gist of the present invention. The present invention is not limited to the embodiments.

Industrial applicability

Embodiments of the present invention can be widely applied to various apparatuses having various motors, such as a dust collector, a dryer, a ceiling fan, a washing machine, a refrigerator, and a power steering apparatus.

Description of the reference symbols

1: a motor; 2: a stator; 3: a rotor; 5: a motor control system; 31: a shaft; 31. 32: a magnet; 40: a rotor core; 51: a motor rotation angle sensor; 52: an inverter; 53: a control calculation unit; 531: a torque ripple compensation calculation unit; 5312: an inverse characteristic calculation processing unit; 532: a current limit calculation unit; 533: a voltage control calculation unit; 534: an induced voltage compensation operation unit; 535: a 2-axis/3-phase converting section; 536: a dead time compensation calculation unit; 537: a PWM control operation unit; 9: an electric power steering apparatus; 100: a motor unit.

Claims

1. A motor control system for driving a motor having a number of phases n of 3 or more,

the motor control system includes:

an inverter that drives the motor; and

a control calculation unit that calculates a current command value indicating a current supplied from the inverter to the motor based on a target current command value externally supplied as a control target of the motor, and controls the inverter by feedback control in which an actual current detection value indicating a current supplied from the inverter to the motor is fed back to the current command value,

the control calculation unit includes:

a voltage control calculation unit that calculates a voltage command value indicating a voltage applied from the inverter to the motor, based on a current deviation between the current command value and the actual current detection value; and

a torque ripple compensation operation section that adds a compensation value that compensates for torque ripple in the motor to a signal value on a downstream side of a signal flow via the voltage control operation section,

the torque ripple compensation calculation unit includes:

a phase compensation unit that calculates a compensation value component of the voltage control calculation unit based on an actual angular velocity value indicating an angular velocity of rotation of the motor; and

and an inverse characteristic calculation processing unit that calculates a compensation value component that compensates for the torque ripple, based on an inverse characteristic of an electrical characteristic of the motor.

2. The motor control system of claim 1,

the motor control system drives the motor of 8P 12S.

3. The motor control system according to claim 1 or 2, wherein,

the motor control system drives an SPM motor equipped with a magnet on the surface of a rotor.

4. The motor control system according to any one of claims 1 to 3,

the motor control system drives a motor for vehicle travel.

5. A power steering system, having:

a motor control system as claimed in any one of claims 1 to 3;

a motor controlled by the motor control system; and

and a power steering mechanism driven by the motor.