JP2008253005A - Motor apparatus and driving method of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve high speed rotation of a magnet motor without demagnetizing the permanent magnet of the magnet motor irreversibly. <P>SOLUTION: A motor unit (7) comprises a motor (3) having a rare earth permanent magnet, and a motor drive (4) for setting the lead phase of motor current for a speed electromotive voltage generated by the magnetic flux of a permanent magnet not to cause irreversible demagnetization of the permanent magnet depending on the speed electromotive voltage of the motor (3) and the amount of magnetic flux of the permanent magnet and driving the motor (3) based on the lead phase. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor device and a motor driving method including a magnet motor having a rare earth permanent magnet and a driving device thereof.

  Conventionally, a motor has been used as a drive source for a pump, a compressor, and the like, and an example thereof is a magnet motor disclosed in Patent Document 1.

This magnet motor is a brushless motor in which a winding is wound around a stator and a rotor has a permanent magnet.
JP 2001-199355 A

  By the way, depending on the operating state of a pump, a compressor, or the like that is a target for driving the magnet motor, the magnet motor may be required to rotate at high speed. However, in the above-described magnet motor such as a brushless motor, when the magnet motor is rotated, a speed electromotive force is generated in the winding. When the rotational speed of the magnet motor increases, the difference between the output voltage of the inverter and the speed electromotive voltage cannot be sufficiently obtained, and current does not flow to the winding.

  Therefore, it is conceivable to suppress the speed electromotive force by advancing the phase of the motor current energized in the winding in the direction of weakening the magnetic flux of the permanent magnet of the magnet motor. By doing so, the difference between the output voltage of the inverter and the speed electromotive voltage can be secured, and the magnet motor can be rotated at a higher speed.

  However, the magnetic flux of the permanent magnet has a characteristic that fluctuates with temperature changes. And when the magnetic flux is decreasing due to the temperature change of the permanent magnet, as described above, when the control for advancing the phase of the motor current is performed, the magnetic field acts on the permanent magnet in the direction of further decreasing the magnetic flux, There is a risk that the permanent magnet will be irreversibly demagnetized.

  This invention is made | formed in view of this point, The place made into the objective is to implement | achieve high-speed rotation of a magnet motor, without irreversibly demagnetizing the permanent magnet of a magnet motor.

  In the present invention, when the phase of the motor current is advanced with respect to the speed electromotive force and the speed electromotive force is suppressed, the advance phase is set in consideration of the amount of magnetic flux of the permanent magnet.

  Specifically, the motor device according to the first aspect of the present invention relates to a magnet motor (3) having a rare earth permanent magnet and the phase of the motor current with respect to the speed electromotive force generated by the magnetic flux of the permanent magnet. Is set according to the speed electromotive voltage of the magnet motor (3) and the amount of magnetic flux of the permanent magnet so that irreversible demagnetization does not occur in the motor, and drives the magnet motor (3) based on the advance phase It shall be provided with a drive device (4).

  In the case of the above-described configuration, the speed electromotive force generated as a whole in the magnet motor (3) can be suppressed by advancing the phase of the motor current in accordance with the speed electromotive force due to the magnetic flux of the permanent magnet. ) Can be rotated to a higher rotation range. At this time, by setting the lead phase of the motor current in accordance with the amount of magnetic flux of the permanent magnet, the lead phase can be set to a value in a range where irreversible demagnetization does not occur in the permanent magnet. Magnetism can be prevented.

  According to a second invention, in the first invention, the apparatus further comprises temperature detection means (31) for detecting a physical quantity related to the temperature of the permanent magnet, and the motor driving device (4) is responsive to the amount of magnetic flux of the permanent magnet. The advance phase is set based on the detection result of the temperature detection means (31).

  Since the amount of magnetic flux of the permanent magnet varies depending on the temperature of the permanent magnet, the amount of magnetic flux can be estimated from the temperature of the permanent magnet. Therefore, in the case of the above-described configuration, instead of directly measuring the magnetic flux amount of the permanent magnet, the temperature detection means (31) detects a value related to the temperature of the permanent magnet, and the detection result is used for the magnetic flux amount of the permanent magnet. Instead, it is used to set the lead phase. By doing so, it is possible to realize the setting of the lead phase in consideration of the amount of magnetic flux of the permanent magnet with a simple configuration including the temperature detecting means (31).

  In a third aspect based on the second aspect, the motor drive device (4) determines the advance phase determined according to the speed electromotive force of the magnet motor (3) as the temperature of the permanent magnet of the magnet motor (3). When the temperature of the permanent magnet of the magnet motor (3) is low, it is set to be large when the temperature is high.

  In the rare earth permanent magnet, the amount of magnetic flux decreases as the temperature increases, and the possibility of irreversible demagnetization increases. Therefore, in the above configuration, the permanent magnet can be prevented from being irreversibly demagnetized by setting the advance phase to be small when the temperature of the permanent magnet is high.

  In addition, when the temperature of the permanent magnet is high, the amount of magnetic flux is small, and as a result, the speed electromotive force of the magnet motor (3) is also small. Therefore, if the advance phase is not corrected based on the temperature of the permanent magnet, As a result, the phase is advanced more than necessary, and the drive efficiency of the motor is lowered, or the drive of the motor cannot be accurately controlled in a desired operation state. Therefore, in the above configuration, by setting the advance phase to be small when the temperature of the permanent magnet is high, the advance phase is set according to the fluctuation of the speed electromotive force of the magnet motor (3) due to the temperature change of the permanent magnet. The magnet motor (3) can be driven and controlled with high accuracy as desired.

  The fourth invention is directed to a motor driving method for driving a magnet motor (3) having a rare earth permanent magnet. The lead phase of the motor current with respect to the speed electromotive force generated by the magnetic flux of the permanent magnet is set so that the speed electromotive force of the magnet motor (3) and the amount of magnetic flux of the permanent magnet are such that no irreversible demagnetization occurs in the permanent magnet. And the magnet motor (3) is driven based on the advance phase.

  In the case of the above-described configuration, the speed electromotive force generated as a whole in the magnet motor (3) can be suppressed by advancing the phase of the motor current in accordance with the speed electromotive force due to the magnetic flux of the permanent magnet. ) Can be rotated to a higher rotation range. At this time, by setting the lead phase of the motor current in accordance with the amount of magnetic flux of the permanent magnet, the lead phase can be set to a value in a range where irreversible demagnetization does not occur in the permanent magnet. Magnetism can be prevented.

  According to a fifth aspect, in the fourth aspect, the advance phase is set according to the amount of magnetic flux of the permanent magnet based on the temperature of the permanent magnet.

  In the case of the above-described configuration, the advance phase is set using the temperature of the permanent magnet instead of directly measuring the amount of magnetic flux of the permanent magnet. Since it is easier to measure the temperature of the permanent magnet or related temperature than to measure the amount of magnetic flux of the permanent magnet, it is possible to realize the setting of the lead phase in consideration of the amount of magnetic flux of the permanent magnet with a simple configuration. it can.

  In a sixth aspect based on the fifth aspect, the lead phase required in accordance with the speed electromotive voltage of the magnet motor (3) is set to be small when the temperature of the permanent magnet of the magnet motor (3) is high. On the other hand, when the temperature of the permanent magnet of the magnet motor (3) is low, it is set larger.

  In the case of the above configuration, the permanent magnet can be prevented from being irreversibly demagnetized by setting the lead phase to be small when the temperature of the permanent magnet is high. Also, by setting the lead phase to be small when the temperature of the permanent magnet is high, the lead phase can be set according to the fluctuation of the speed electromotive force of the magnet motor (3) due to the temperature change of the permanent magnet, The magnet motor (3) can be driven with high accuracy as desired.

  According to the present invention relating to the motor device, by setting the advance phase of the motor current with respect to the speed electromotive force generated by the magnetic flux of the permanent magnet according to the speed electromotive force of the magnet motor (3) and the amount of magnetic flux of the permanent magnet, An appropriate lead phase corresponding to the speed electromotive force can be set within the range where the permanent magnet is not irreversibly demagnetized, and the magnet motor (3) can be rotated at high speed while preventing irreversible demagnetization of the permanent magnet. Can do.

  According to the second invention, by providing the temperature detection means (31) for detecting the value related to the temperature of the permanent magnet of the magnet motor (3), the amount of magnetic flux of the permanent magnet can be easily estimated. The present invention can be realized with a simple configuration as compared with a configuration in which the amount of magnetic flux is directly measured.

  According to the third aspect of the present invention, the irreversible demagnetization of the permanent magnet can be prevented by correcting and setting the lead phase to be small when the temperature of the permanent magnet is high according to the rare earth permanent magnet. In addition, it is possible to realize accurate drive control of the magnet motor (3) according to the temperature characteristics of the magnetic flux amount of the permanent magnet and, consequently, the temperature characteristics of the speed electromotive voltage of the magnet motor (3).

  Further, according to another aspect of the present invention relating to the motor driving method, the advance phase of the motor current with respect to the speed electromotive force generated by the magnetic flux of the permanent magnet is determined according to the speed electromotive force of the magnet motor (3) and the amount of magnetic flux of the permanent magnet. By setting it, it is possible to set an appropriate advance phase according to the speed electromotive force in a range where the permanent magnet does not irreversibly demagnetize, and prevent the irreversible demagnetization of the permanent magnet, while rotating the magnet motor (3) at high speed. Can be realized.

  According to the fifth aspect of the present invention, the present invention has a simple configuration as compared with the configuration in which the amount of magnetic flux of the permanent magnet is directly measured by estimating the amount of magnetic flux of the permanent magnet from the temperature of the permanent magnet of the magnet motor (3). Can be realized.

  According to the sixth aspect of the present invention, the irreversible demagnetization of the permanent magnet can be prevented by correcting and setting the lead phase to be small when the temperature of the permanent magnet is high according to the rare earth permanent magnet. In addition, it is possible to realize accurate drive control of the magnet motor (3) according to the temperature characteristics of the magnetic flux amount of the permanent magnet, and consequently the temperature characteristics of the speed electromotive voltage of the magnet motor (3).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 2, the motor unit (7) according to the embodiment of the present invention is employed in a power steering device (2) provided in the steering mechanism (1).

  The steering mechanism (1) includes a steering wheel (11) operated by a driver, a steering shaft (12) coupled to the steering wheel (11), tie rods (not shown) and knuckle (not shown) at both ends. And a rack and pinion mechanism (14) for connecting the steering shaft (12) and the rack shaft (13) to each other. I have. In other words, when the driver rotates the steering wheel (11), the rotation is transmitted as a linear motion along the axial direction to the rack shaft (13) via the rack and pinion mechanism (14), and the steering is performed. Wheels (15,15) steer.

  The power steering device (2) is a device for assisting the operation of the steering wheel (11) by the driver. Specifically, the power steering device (2) includes a power cylinder (20) that supplies auxiliary steering force to the rack shaft (13), and a hydraulic mechanism (21) that operates the power cylinder (20). .

  The power cylinder (20) includes a piston (20a) provided integrally with the rack shaft (13) and an internal space partitioned into a right chamber (20c) and a left chamber (20d) by the piston (20a). Cylinder (20b).

  The hydraulic mechanism (21) includes a hydraulic pump (23) for supplying hydraulic oil in the reservoir tank (22) to the power cylinder (20), and a power cylinder (20) according to the operation of the steering wheel (11). A control valve (24) for adjusting the oil amount and hydraulic pressure to the motor and a motor unit (7) for driving the hydraulic pump (23) are provided.

  A suction pipe (23a) and a discharge pipe (23b) are connected to the hydraulic pump (23). The upstream end of the suction pipe (23a) is connected to the reservoir tank (22), while the downstream end of the discharge pipe (23b) is connected to the control valve (24). The hydraulic pump (23) is driven by the motor (3) to suck up the hydraulic oil in the reservoir tank (22) via the suction pipe (23a), and discharge the hydraulic oil to the discharge pipe (23b) and Supply to the power cylinder (20) through the control valve (24).

  The control valve (24) is configured such that the rotation of the steering shaft (12) is input directly or indirectly, and the rotation of the steering shaft (12), that is, the steering wheel (11) Adjust the oil amount, hydraulic pressure, and supply direction of the hydraulic oil supplied from the hydraulic pump (23) according to the operation, and connect the right chamber (20c) of the power cylinder (20) or through the piping (25a, 25b) Supply hydraulic fluid to the left chamber (20d). Specifically, when the steering wheel (11) is rotated in one direction, the control valve (24) allows the hydraulic oil pumped from the hydraulic pump (23) to pass through the cylinder (25a, 25b) through the cylinder. Supply to one of the right chamber (20c) and the left chamber (20d) of (20b). In addition, when the steering wheel (11) is rotated in the other direction, the control valve (24) allows the hydraulic oil pumped from the hydraulic pump (23) to pass through the other of the pipes (25a, 25b) through the cylinder ( 20b) is supplied to the other of the right chamber (20c) and the left chamber (20d). The hydraulic oil that has returned from the power cylinder (20) to the control valve (24) via one of the pipes (25a, 25b) is returned to the reservoir tank (22) via the pipe (24a).

  Thus, when the hydraulic oil is supplied to either the right chamber (20c) or the left chamber (20d) of the cylinder (20b), the power cylinder (20) applies hydraulic pressure to the piston (20a), and the rack shaft A steering assist force acts on the portion (13).

  The motor unit (7) includes a brushless DC motor (hereinafter also simply referred to as a motor) (3) that drives a hydraulic pump (23), and a motor drive device (4) that drives the motor (3). Yes.

  Although not shown, the motor (3) includes a rotor provided with a permanent magnet, and a stator disposed around the rotor and having a winding. The permanent magnet of this rotor is a rare earth magnet. The motor (3) is driven by supplying a three-phase alternating current to the winding from the motor driving device (4). This motor (3) constitutes a magnet motor.

  As shown in FIG. 1, the motor drive device (4) includes an inverter output unit (5) for supplying a three-phase alternating current to the motor (3), and a control unit (6) for controlling the inverter output unit (5). And.

  The inverter output unit (5) has a plurality of switching elements, and outputs three-phase alternating current to the motor (3) by switching on / off of the switching elements by PWM control. This motor drive device (4) constitutes a drive device.

  The control unit (6) includes a speed command value setting unit (60) for calculating the rotation speed command value ω * of the motor (3), a speed detection unit (61) for determining the rotation speed ω of the motor (3), A proportional-plus-integral calculator (62) that calculates a current command value Ia * from a deviation between the rotational speed command value ω * and the rotational speed ω, and d representing the current command value Ia * in dq coordinates based on the rotational speed ω. A dq current command value calculation unit (63) for obtaining an axis current command value id * and a q axis current command value iq *, and correcting the d axis current command value id * according to the temperature of the motor (3) A d-axis current id and a q-axis current representing, in dq coordinates, any two-phase AC of the three-phase AC supplied to the motor (3) and the correction unit (64) that outputs the current correction value id * ' a coordinate converter (65) for converting to iq, a deviation between the d-axis current correction value id * ′ and the d-axis current id, and the q-axis current command value a proportional-plus-integral calculator (66) for obtaining the d-axis voltage command value vd * and the q-axis voltage command value vq * based on the deviation between q * and the q-axis current iq, respectively, and the d-axis voltage command values vd * and q A space vector modulator (67) for space vector modulating the shaft voltage command value vq * and outputting a three-phase voltage command value to be applied to the three phases of the motor (3).

  The speed command value setting unit (60) is a rotational speed of the motor (3) required to drive the hydraulic pump (23) based on at least the rotation (rotation amount, rotational speed, etc.) of the steering shaft part (12). Is calculated and output as a rotational speed command value ω *.

  The speed detector (61) receives the output signal of the encoder (32), and obtains and outputs the current rotational speed ω of the motor (3) by differentiating the output signal. For example, the encoder (32) outputs a pulse signal synchronized with the rotation of the rotor of the motor (3), and the speed detector (61) determines the rotational speed of the motor (3) based on the interval of this pulse signal. ω is calculated.

  The proportional integral calculator (62) receives a deviation between the rotational speed command value ω * set by the speed command value setting unit (60) and the rotational speed ω detected by the speed detection unit (61), Based on the deviation, a current command value Ia * is obtained and output.

  The dq current command value calculation unit (63) receives the current command value Ia * calculated by the proportional integration calculator (62) and the rotation speed ω detected by the speed detection unit (61), and the current command value Ia Based on * and the rotational speed ω, a d-axis current command value id * and a q-axis current command value iq * are obtained and output.

  Specifically, the dq current command value calculation unit (63) first determines whether or not to advance the phase of the current command value Ia * based on the current command value Ia * and the rotation speed ω. Specifically, the difference between the output voltage that can be output from the inverter output section (5) and the speed electromotive voltage generated in the motor (3) when the motor (3) is driven at the rotational speed ω is the current command value Ia Determine whether * is enough to energize the motor (3). When the difference between the output voltage of the inverter output section (5) and the speed electromotive voltage of the motor (3) is not sufficient, the difference is a value sufficient to pass the current command value Ia * to the motor (3). The lead phase of the current command value Ia * is set so that The advance phase may be set by the dq current command value calculation unit (63) from a map of the current command value Ia *, the rotation speed ω, and the advance phase, or the current command value Ia * and the rotation speed ω You may calculate from the function showing the relationship with a lead phase. After the dq current command value calculation unit (63) sets the advance phase in this manner, the dq current command value id * that is the d-axis component and the q-axis current command value iq that is the q-axis component are set to the current command value Ia *. * Decomposes.

  The correction unit (64) receives the detection signal of the temperature sensor (31) that detects the temperature of the motor (3), and the d-axis current command value id * calculated by the dq current command value calculation unit (63). Is corrected based on the detection signal from the temperature sensor (31). The temperature sensor (31) can be attached to an arbitrary location such as a housing (not shown) or a stator of the motor (3) as long as the temperature of the permanent magnet of the rotor can be estimated.

  Specifically, the correction unit (64) holds a correction map representing the correlation between the motor temperature and the d-axis current, and d input from the dq current command value calculation unit (63) in accordance with this correction map. The shaft current command value id * is corrected and the d-axis current correction value id * ′ is output. That is, the amount of magnetic flux of the permanent magnet of the motor (3) varies according to the temperature change of the permanent magnet, and the temperature of the permanent magnet can be estimated from the detection signal of the temperature sensor (31). As will be described in detail later, the magnitude of the lead phase of the current command value Ia * can be adjusted by adjusting the magnitude of the d-axis current command value id *. That is, correcting the d-axis current command value id * according to the correction map based on the detection signal of the temperature sensor (31) and outputting the d-axis current correction value id * ′ means that the motor current advance phase. Is corrected according to the amount of magnetic flux of the permanent magnet. The correction of the d-axis current command value id is not limited to the correction map, but may be configured to calculate from a function representing the relationship between the motor temperature and the d-axis current.

  The coordinate converter (65) includes any two-phase AC current (in this embodiment, U-phase current iu and W-phase current iw) of the three-phase AC supplied to the motor (3) and an encoder (32 ) Is input, and the two-phase currents iu and iw are converted into a d-axis current id and a q-axis current iq expressed in dq coordinates and output.

  The proportional-plus-integral calculator (66) includes a deviation between the d-axis current correction value id * ′ corrected by the correction unit (64) and the d-axis current id converted by the coordinate converter (65), and a dq current command. The deviation between the q-axis current command value iq * calculated by the value calculation unit (63) and the q-axis current iq converted by the coordinate converter (65) is input, and the d-axis voltage command value vd * and the q-axis voltage are input. The command value vq * is obtained and output.

  The space vector modulator (67) receives the d-axis voltage command value vd * and q-axis voltage command value vq * obtained by the proportional-plus-integral calculator (66) and the output signal of the encoder (32). The voltage command value vd * and the q-axis voltage command value vq * are subjected to space vector modulation to obtain a three-phase voltage command value to be applied to the motor (3) and output it to the inverter output unit (5).

  The inverter output unit (5) receives the three-phase voltage command value output from the space vector modulator (67), creates a pulse signal subjected to PWM modulation, and inputs the pulse signal to each switching element. Thus, three-phase alternating current corresponding to the three-phase voltage command value is output to the motor (3). In the present embodiment, a 180-degree energization method is adopted. By doing so, torque pulsation can be suppressed and vibration can be reduced, and generation of harmonics can be suppressed and loss can be reduced.

  The current phase control by the motor drive device (4) configured as described above will be described in more detail.

  First, the case where current phase control is not performed will be described with reference to FIG.

In the dq coordinate, the magnetic flux Φm of the permanent magnet of the motor (3) is expressed so as to extend in the positive direction on the d-axis, and the motor current supplied to the winding of the motor (3) is directed in the positive direction on the q-axis. Expressed to extend. The winding to which the motor current is supplied creates a magnetic flux Lqiq in the same direction as the motor current Ia. As a result, a combined magnetic flux Φ ₀ is created by the magnetic flux Φm of the permanent magnet and the magnetic flux Lqiq created by the winding. Then, a speed electromotive voltage ωΦm by magnetic flux Φm of permanent magnets that advances 90 ° the phase by multiplying omega flux Φm permanent magnets (extending in the positive direction of the q-axis), multiplied by a synthetic magnetic flux [Phi ₀ omega The phase advanced by 90 ° is the speed electromotive force ωΦ ₀ generated in the entire motor (3). The terminal voltage Va is obtained by adding the voltage drop RaIa of the winding resistance to the speed electromotive force ωΦ ₀ of the entire motor (3).

Here, as the rotational speed ω of the motor (3) increases, the speed electromotive force ωΦ ₀ increases. On the other hand, the terminal voltage Va cannot be increased beyond the maximum output voltage of the inverter output section (5). Therefore, when the rotational speed ω is too fast, the difference between the output voltage and the speed electromotive voltage Omegafai ₀ of the inverter output section (5) is not sufficiently achieved, making it impossible to energize the winding. Thus, the motor (3) is the rotation speed ω of being restricted upper limit in relation to the speed electromotive voltage ωΦ _0.

  Therefore, the motor drive device (4) causes the dq current command value calculation unit (63) to change the phase of the motor current Ia from the speed electromotive force ωΦm due to the magnetic flux Φm of the permanent magnet according to the rotational speed ω of the motor (3). I am trying to proceed.

Specifically, as shown in FIG. 4, the phase of the motor current Ia is advanced by the phase β with respect to the speed electromotive force ωΦm caused by the magnetic flux Φm of the permanent magnet. By doing so, the combined magnetic flux Φ ₀ is reduced, and the speed electromotive force ωΦ _{0 of the} entire motor (3) is also reduced. As a result, a sufficient difference between the terminal voltage Va and the speed electromotive force ωΦ ₀ can be secured. That is, a larger motor current Ia can be applied, and the motor (3) can be rotated to a higher rotation range.

  Thus, when the phase of the motor current Ia is advanced, the d-axis current id which is the d-axis component is included in the motor current Ia. The d-axis magnetic flux Ldid due to this d-axis current id acts in the direction of weakening the magnetic flux Φm of the permanent magnet. That is, if the d-axis magnetic flux Ldid becomes too large, the permanent magnet may be irreversibly demagnetized. Therefore, the lead phase β of the motor current Ia is set in a range where the d-axis magnetic flux Ldid does not irreversibly demagnetize the magnetic flux Φm of the permanent magnet (reversible demagnetization range).

  However, the amount of magnetic flux of a permanent magnet changes depending on its temperature, and the range of reversible demagnetization also changes. Therefore, even if the lead phase β is supposed to be set in a range that does not cause irreversible demagnetization, depending on the temperature of the permanent magnet, a d-axis magnetic flux Ldid that can cause the permanent magnet to irreversibly demagnetize may be generated. is there.

Further, when the magnetic flux Φm of the permanent magnet changes with temperature, the speed electromotive force ωΦ ₀ also changes, and as a result, the required advance phase β also changes. That is, there is a possibility that the advance phase β calculated by the dq current command value calculation unit (63) is excessively advanced or insufficient in the actual magnetic flux Φm of the permanent magnet. If the phase of the motor current Ia is excessively advanced, the drive efficiency of the motor (3) is reduced. On the other hand, if the phase of the motor current Ia is not sufficient, the permanent magnet may be irreversibly demagnetized. Is also not preferable.

  Therefore, the motor drive device (4) calculates the advance phase β of the motor current Ia at a predetermined reference temperature in the dq current command value calculation unit (63), and then calculates the advance phase β in the correction unit (64) as a permanent magnet. Is corrected based on the temperature (specifically, the temperature detected by the temperature sensor (31)). Specifically, the amount of magnetic flux of the rare earth magnet decreases as the temperature increases, as shown in FIG. Accordingly, the correction unit (64) advances the phase β so that the advance phase β decreases as the detection temperature of the temperature sensor (31) increases, while the advance phase β increases as the detection temperature of the temperature sensor (31) decreases. Correct. By doing so, it is possible to prevent irreversible demagnetization of the permanent magnet and to set the advance phase β that matches the actual magnetic flux Φm of the permanent magnet.

  Therefore, according to the present embodiment, the phase of the motor current is changed according to the speed electromotive voltage of the entire motor (3) (specifically, the magnitude of the motor current and the target rotational speed of the motor (3)). By controlling the speed electromotive force due to the magnetic flux of the motor, the speed electromotive force of the entire motor (3) is suppressed and the motor (3) is rotated in a higher rotation range without increasing the size of the motor (3). be able to. At this time, the permanent phase of the permanent magnet is prevented from being irreversibly demagnetized by correcting the lead phase of the motor current according to the amount of magnetic flux of the permanent magnet (specifically, the temperature of the motor (3)). In addition, the motor (3) can be driven and controlled accurately with a desired behavior by setting a lead phase that matches the magnetic flux of the permanent magnet that varies with temperature.

  In addition, when correcting the lead phase of the motor, the amount of magnetic flux of the permanent magnet is not actually measured, but based on the temperature of the permanent magnet, specifically, the temperature of the motor (3). Thus, it is possible to realize the advance phase correction based on the amount of magnetic flux of the permanent magnet with a simple configuration of the temperature sensor (31).

  Furthermore, by adopting a rare earth magnet as the permanent magnet of the motor (3), the motor (3) can be rotated at high speed without irreversibly demagnetizing the permanent magnet even when the permanent magnet is at a low temperature. can do. That is, when a ferrite magnet is used as a permanent magnet, the amount of magnetic flux decreases as the temperature of the ferrite magnet decreases, and irreversible demagnetization is likely to occur. It is necessary to set so that the advance phase becomes smaller as the temperature of the permanent magnet becomes lower. However, since the viscosity of the hydraulic oil in the hydraulic mechanism of the power steering device (2) decreases at a low temperature, the motor (3) requires a higher torque than at a high temperature. However, as described above, in the case of a motor having a ferrite magnet, it is easy to irreversibly demagnetize at low temperatures, and there is a limit even if the phase of the motor current is advanced to prevent irreversible demagnetization. Therefore, there is a possibility that the motor (3) cannot be driven with sufficient torque. On the other hand, in the case of a motor (3) having a rare earth magnet, the amount of magnetic flux is large and the holding power is large at low temperatures where high torque is required, and the motor current phase is sufficiently increased. Torque can be generated.

<< Other Embodiments >>
The present invention may be configured as follows with respect to the embodiment.

  That is, after the motor drive device (4) calculates the d-axis current command value id * and the q-axis current command value iq * of the motor current Ia to which the advance phase is added by the dq current command value calculation unit (63), The d-axis current command value id * is corrected by the correction unit (64), but is not limited to this. For example, even if the dq current command value calculation unit (63) corrects the advance phase when obtaining the motor current Ia with the advance phase based on the magnetic flux amount of the permanent magnet (specifically, the motor temperature). Good. In other words, any configuration can be adopted as long as the lead phase is set according to the speed electromotive force of the motor and the amount of magnetic flux of the permanent magnet.

  The motor drive device (4) estimates the temperature of the permanent magnet and the amount of magnetic flux of the permanent magnet based on the detection result of the temperature sensor (31) provided in the motor (3). It is not limited. For example, the discharge temperature of the hydraulic oil discharged from the hydraulic pump (23) may be measured, and the temperature of the permanent magnet and the amount of magnetic flux may be estimated from the measured temperature. Alternatively, the temperature of the permanent magnet may be estimated by calculating the amount of heat generated in the motor (3) by integrating the motor current over time, and the amount of magnetic flux may be estimated. That is, any configuration can be adopted as long as the amount of magnetic flux of the permanent magnet can be estimated.

  Furthermore, the motor (3) is not limited to a brushless motor, and any motor can be employed as long as it has a permanent magnet and generates a speed electromotive force by its rotation.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a motor device and a motor driving method including a magnet motor having a rare earth permanent magnet and a driving device thereof.

It is a block diagram which shows the structure of the motor unit which concerns on embodiment of this invention. It is the schematic which shows the structure of a steering mechanism. It is a current vector diagram of a motor current when current phase control is not performed. It is a current vector diagram of a motor current when performing current phase control. It is a graph which shows the correlation with the magnetic flux amount and temperature of a rare earth magnet.

Explanation of symbols

3 Motor (Magnet motor)
4 Motor drive device
31 Temperature sensor (temperature detection means)
63 dq current command value calculation unit (phase setting unit)
64 Correction section (Phase setting section)
7 Motor unit (motor unit)

Claims (6)

A magnet motor (3) having a rare earth permanent magnet;
The lead phase of the motor current with respect to the speed electromotive force generated by the magnetic flux of the permanent magnet is set to the speed electromotive force of the magnet motor (3) and the amount of magnetic flux of the permanent magnet so that irreversible demagnetization does not occur in the permanent magnet. A motor device comprising: a motor driving device (4) that is set according to the driving phase and drives the magnet motor (3) based on the advance phase. In claim 1,
A temperature detecting means (31) for detecting a physical quantity related to the temperature of the permanent magnet;
The motor drive device (4) sets the advance phase according to the amount of magnetic flux of the permanent magnet based on the detection result of the temperature detection means (31). In claim 2,
The motor drive device (4) sets the advance phase required according to the speed electromotive force of the magnet motor (3) to be small when the temperature of the permanent magnet of the magnet motor (3) is high, while the magnet A motor device characterized in that it is set larger when the temperature of the permanent magnet of the motor (3) is low. A motor driving method for driving a magnet motor (3) having a rare earth permanent magnet,
The lead phase of the motor current with respect to the speed electromotive force generated by the magnetic flux of the permanent magnet depends on the speed electromotive force of the magnet motor (3) and the amount of magnetic flux of the permanent magnet so that irreversible demagnetization does not occur in the permanent magnet. And driving the magnet motor (3) based on the advance phase. In claim 4,
A motor driving method comprising setting a lead phase according to a magnetic flux amount of the permanent magnet based on a temperature of the permanent magnet. In claim 5,
The advance phase required according to the speed electromotive force of the magnet motor (3) is set to be small when the temperature of the permanent magnet of the magnet motor (3) is high, while the permanent magnet of the magnet motor (3) A motor driving method characterized in that the motor driving method is set to be increased when the temperature is low.

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