JP2007259610A - Synchronous motor driving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synchronous motor driving apparatus capable of smoothly actuating and accelerating a synchronous motor in speed sensorless and position sensorless, and suppressing inversion. <P>SOLUTION: This synchronous motor driving apparatus controls the magnitude of an output voltage, a frequency and a phase, adds a predetermined phase correction value to the phase in activating the synchronous motor, changes the phase correction value one or more times, and corrects the frequency or the phase on the basis of a detection value of an output current. Further, in changing the phase correction value, it is increased, for example, at each angle of not more than 90° so that the phase can be increased in the positive rotation direction of the motor. Further, in initially changing the predetermined phase correction value, a time when the initial phase correction value is set is made to be shorter than a time when the changed phase correction value is set. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor driving device that performs variable speed operation of a synchronous motor, and more particularly to a motor driving device that starts and accelerates a synchronous motor without using a speed and position sensor.

In the speed and position sensorless control of a synchronous motor, the inductance (Ld, Lq) on the magnetic flux axis (d axis) and the axis (q axis) perpendicular to the magnetic flux axis is conventionally superimposed on the output current or output voltage. There is a method of detecting the speed and magnetic pole position using the difference between the two. FIG. 10 shows the technique of Patent Document 1 as a conventional technique. In FIG. 10, the synchronous motor is a permanent magnet type synchronous motor, but the operation is the same even with a wound type synchronous motor with a field device. The speed control unit 103 calculates the torque command value τ ^* using the speed command value ωr ^* and the speed estimation value ωr ^ calculated by the speed estimation unit 112. The torque command value τ ^* includes harmonic components for harmonic superposition described later, and passes through the notch filter unit 104 to remove the harmonic components. The current command calculation unit 105 calculates a torque current command It ^* and an excitation current command Im ^* based on the torque command value τ ^* . Here, in the vector control of the synchronous motor, as shown in FIG. 11, the phase difference Δφ of the m-axis (axis perpendicular to the torque current) and the t-axis (axis parallel to the torque current) is zero with respect to the d-axis and the q-axis. Need to be controlled. Next, the harmonic current generator 113 generates a current harmonic ΔIm ^* having a predetermined amplitude and frequency. The current harmonic ΔIm ^* is added to the excitation current command Im ^* , and the current control unit 106 outputs a three-phase AC voltage command using the phase θ by the phase calculation unit 109 and the current detection value from the current detector 107. The current control unit 106 calculates a t-axis voltage command Vt ^* and an m-axis voltage command Vm ^* , and calculates a three-phase AC voltage command by coordinate conversion using the phase θ. The power converter unit 101 applies a voltage to the synchronous motor 102 based on the AC voltage command. The voltage detector 108 detects the voltage, and the harmonic voltage detector 110 extracts the harmonic component Vh perpendicular to the m-axis and having the same frequency as ΔIm. Then, the speed error detector 111 calculates a speed error Δω ^ using the harmonic components Vh and ΔIm. The prior art uses the structure of the motor or the saliency of the magnetic flux. For example, when there is a relationship of Lq> Ld, the speed error Δω ^ has a relationship as shown in (Expression 1). ωh is the frequency of the harmonic component.

Δω ^ = − (positive constant) · sin (2 · Δφ) · ωh · (Lq−Ld) (Equation 1)
In the equation (1), Δω ^ <0 when Δφ> 0, and Δω ^> 0 when Δφ <0. The speed estimation unit 112 outputs the speed error Δω ^ as a speed estimation value ωr ^ by a proportional integration circuit. Thereby, when the m-axis is delayed from the d-axis (Δφ <0), the speed estimated value ωr ^ is increased (Δω ^> 0), and when the m-axis is advanced from the d-axis (Δφ> 0) Performs the speed estimation by slowing down the speed estimation value ωr ^ (Δω ^ <0). Although FIG. 10 superimposes harmonics on the current and detects the voltage, as another method, the harmonic voltage is superimposed on the voltage command, and the superimposed voltage and the current detection value are used similarly. I can do things.

Japanese Patent No. 3484058 (Description of paragraphs (0011) to (0019))

  However, in the prior art, because of harmonic superimposition, torque ripple occurs, and there is a concern about the influence of mechanical resonance and the like, making it difficult to start smoothly. In addition, when using saliency, for example, in the case of a synchronous motor having a damper winding, the saliency becomes small due to the influence of the damper winding, making it difficult to apply the conventional technique. Further, when voltage detection is necessary, it is easily affected by a voltage detection error at a low speed. Furthermore, the motor may reverse due to the control phase error due to the harmonics or voltage detection error, and a problem arises when the angle that can be reversed is limited due to mechanical constraints. Furthermore, the design of the speed control system and speed estimation system requires electric motor and mechanical system constants, and it is difficult to apply to those that are not clearly understood.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a synchronous motor drive device that has a simple configuration, smoothly starts without torque ripple, and has a reduced reverse angle when starting a synchronous motor without speed and position sensors.

  The synchronous motor driving device of the present invention controls the magnitude, frequency, and phase of the output voltage, and drives the synchronous motor. At the time of startup, the synchronous motor driving device adds a predetermined phase correction value to the phase, and the phase correction value Is changed once or more, and the frequency or phase is corrected based on the detected current value. Further, when changing the predetermined phase correction value, it is increased by, for example, 90 ° or less so as to increase the phase in the forward rotation direction of the electric motor. In addition, when the predetermined phase correction value is first changed, the time for setting the first phase correction value is set shorter than the time for setting the phase correction value after the change. The torque current command value of the motor is a predetermined value that does not exceed the rated current value, and the torque current command value before the predetermined phase correction value is first changed is the value after the first change of the phase correction value. Make it smaller than the torque current command value. The frequency correction value or the phase correction value based on the current detection value is calculated based on the current detection value that vibrates at the same frequency as the vibration of the rotation speed of the electric motor.

  According to the present invention, when starting and accelerating a synchronous motor without speed and position sensors, it is possible to suppress the reverse rotation with a simple configuration and no torque ripple. For this reason, it can be applied to a case where the mechanical system is not burdened and the electric motor and the machine constant are unknown.

  The details of the present invention will be described below with reference to the drawings.

With respect to the induction motor driving apparatus of the present embodiment, parts different from the prior art of FIG. 10 will be described using FIGS. 1 to 3. Note that these relate to a control method from startup to acceleration to a predetermined speed. In the torque command value setting unit 1, for example, about 60% of the rated torque is set as the torque command value τ ^* , corresponding to acceleration torque + load torque. Next, the current command calculation unit 105 sets the torque current command It ^* = predetermined value and the excitation current command Im ^* = 0. Since a magnetic flux is separately generated by the field current of the field device, generally, Im = 0 is controlled. At this time, the currents Id and Iq, the magnetic fluxes Φd and Φq, and the generated torque τm of the synchronous motor 102 are as shown in Expressions (2) to (6), respectively. The phase difference Δφ is the phase shift between the d-axis and the m-axis shown in FIG. 11, and Md, If, and P are the d-axis mutual inductance, the field current, and the number of poles of the motor, respectively.

Id = −sin (Δφ) · It ^* (Equation 2)
Iq = cos (Δφ) · It ^* (Equation 3)
Φd = Ld · Id + Md · If (Equation 4)
Φq = Lq · Iq (Equation 5)
τm = 3 · (P / 2) · (Φd · Iq−Φq · Id) (Equation 6)
Here, the generated torque τm and the phase difference Δφ have a relationship as shown in FIG. 2. For example, as shown in FIG. 2, when the torque required for starting the motor is 30% of the rated torque, as shown in FIG. There are a range of phase difference Δφ that can be activated and an impossible range, and there is a range that is reversed even if activated. When starting the motor, since the initial position of the motor magnetic flux is unknown, the phase difference Δφ varies depending on how the control phase is set, and it is not known which range is included.

  Therefore, the phase correction unit 2 changes the phase correction value Δθ from, for example, phase correction value Δθ = −180 ° → −90 ° → 0 °. The phase correction value Δθ is added to the phase θ and used for coordinate conversion in the current control unit 106 and the coordinate conversion unit 4. As a result, even if the phase difference Δφ = 90 ° ± 20 °, 270 ° ± 20 ° at the start impossible range is initially entered, the startable range is entered by shifting the phase by 90 °, and the motor rotates. The child starts up. Note that the rotor easily rotates in the forward direction by increasing the phase correction value Δθ in the forward direction.

FIG. 3 shows the relationship between the torque current command It ^* , the speed command value ωr ^* , and the phase correction value Δθ. The torque current command It ^* gives a predetermined value. In FIG. 3, the value is initially increased from zero to a predetermined value, but may be a predetermined value from the beginning. The phase correction value Δθ is increased by 90 ° in the range of alignment 1, 2, and 3. In the present embodiment, the phase correction value Δθ is changed twice. However, it is sufficient that the phase correction value Δθ is once or more. The speed command value ωr ^* is increased from a predetermined value, for example, zero. The speed command value ωr ^* may be increased from the beginning. At this time, if the predetermined value of the speed command value ωr ^* is zero, the magnetic pole position (d-axis) of the rotor is parallel to the current axis (t-axis) (phase difference Δφ = 90 ° or 270 °). It tries to make the generated torque τm = 0. As a result, the d-axis rotates toward the phase difference Δφ = 270 °, and initially oscillates there. At this time, a reverse case occurs.

Therefore, the frequency correction value calculation unit 3 detects the rotation speed vibration of the motor from the current detection value, calculates the frequency correction value Δω, and corrects the output frequency, thereby suppressing the rotation vibration and reducing the reverse rotation. To do. The frequency correction value calculation unit 3 is, for example, a proportional circuit and receives ImFB. Since the q axis is aligned with the m axis in FIG. 11 due to the phase difference Δφ = 270 ° at startup, when Iq vibrates due to the influence of the vibration component of the rotor, the vibration component is strong in ImFB. This is because it appears. Therefore, ImFB is used to control the frequency, suppress the vibration of the rotational speed, and reduce the reverse rotation. Further, when a predetermined time has elapsed, the speed command value ωr ^* is increased to accelerate. Also in this case, when the rotational speed vibrates due to the influence of the phase difference Δφ, the frequency correction value Δω is calculated using the current detection value having the same vibration component as the vibration frequency of the rotational speed, and the frequency is controlled. In this case, it is possible to use ItFB without using ImFB in FIG. 1, and the frequency correction value calculation unit 3 is configured by a proportional or proportional integration or incomplete differentiation circuit. As a result, the vibration of the rotational speed can be suppressed during acceleration as well as during startup. Further, the phase θ that is the control phase is calculated by integrating the sum of the speed command value ωr ^* and the frequency correction value Δω by the phase calculation unit 109. As a result, the speed estimation value is not used, so that it is not affected by the speed estimation error due to voltage, current detection error, or the like.

  As described above, in this embodiment, when starting the synchronous motor without the speed and position sensor, the phase that can be started is set, and the reverse rotation is simultaneously reduced. As a result, smooth start-up and acceleration can be performed with simple settings, and the mechanical system is not burdened.

  In the present embodiment, parts different from the first embodiment will be described. In this embodiment, the phase correction value Δθ is changed by 90 ° or less, for example, 90 °, 45 °, 30 °, 10 °, or the like. This makes the rotation more smooth.

  This embodiment will be described with reference to FIG. 4 for differences from the first and second embodiments. In FIG. 4, the time t1 when the phase correction value Δθ is set to the first set value is shorter than the times t2-t1 and t3-t2 at which the phase correction value Δθ is changed thereafter, as compared to FIG. 3 of the first embodiment. To do. In FIG. 11, when the t-axis (current axis) starts from a position that is shifted 180 ° from the d-axis (magnetic pole axis), the start-up is impossible and the demagnetization is caused by the t-axis current. This is because when Δθ changes and the t-axis (m-axis) moves, it may not be activated due to demagnetization. What can be activated within t1 is within the range that can be activated when the phase correction value Δφ is close to 0 and the phase correction value Δθ moves 90 ° next time, so demagnetization at the first phase correction value Δθ. Can be prevented. In this embodiment, the initial phase correction value Δθ is shortened to suppress demagnetization and facilitate startup.

This embodiment will be described with reference to FIG. 5 for differences from the first to third embodiments. In FIG. 5, the torque current command It ^* in the period (positioning 1) where the phase correction value Δθ is initially set is the same as the period (positioning 2, position 3) in which the phase correction value Δθ is changed. It is made smaller than the torque current command It ^* . For example, the alignment 1 is set to 40% of the rated current and 60% after that, so that both do not become overcurrent. This is to reduce the initial torque current command It ^* so that demagnetization is not performed first as in the third embodiment, and it is easy to start up as in the third embodiment.

This embodiment will be described with reference to FIG. 6 for differences from the first to fourth embodiments. In FIG. 6, at the timing when the phase correction value Δθ is changed, the torque current command It ^* is once set to zero and then restored. This is because the phase correction value Δθ can suppress a transient increase in current due to a phase change and prevent overcurrent when the phase correction value Δθ is changed.

  This embodiment will be described with reference to FIG. 7 for differences from the first to fifth embodiments. In FIG. 7, with respect to FIG. 1, the frequency correction value Δω obtained by the frequency correction value calculation unit 3 is integrated by the integration unit 5, corrected to the phase, and the phase θ is corrected. This is equivalent to the first embodiment, and the same effect as the first embodiment can be obtained.

This embodiment will be described with reference to FIG. 8 for differences from the first to sixth embodiments. In FIG. 8, a current command switching unit 11 is provided instead of the phase correction value setting unit 2 with respect to FIG. In the current command switching unit 11, when it is desired to increase the phase θ by 90 ° from the initial value as in the first embodiment, for example, the torque current command It ^* , It ^** and Im ^** are calculated from the excitation current command Im ^* .

It ^** = sin (90 °) · Im ^* + cos (90 °) · It ^* (Expression 7)
Im ^** = cos (90 °) · Im ^* −sin (90 °) · It ^* (Equation 8)
When the excitation current command Im ^* = 0, It ^** = 0 and Im ^** =-It ^* . Next, when it is desired to increase the phase θ by 180 ° from the initial value as in the first embodiment, in the current command switching unit 11, the 90 ° of the formulas (7) and (8) is set to 180 °. It ^** can be calculated as It ^** and Im ^** . This is equivalent to rotating the t-axis and m-axis by a predetermined angle without actually changing the phase θ, and the same effect as in the first embodiment can be obtained.

  This embodiment will be described with reference to FIG. 9 for differences from the first to seventh embodiments. In FIG. 9, an activation availability detection unit 121 is installed with respect to FIG. 1, and it is identified whether activation and acceleration are successfully performed using the current detection value. For example, when the current detection value flows more than a predetermined current, it is regarded as start-up / acceleration failure. Although omitted in FIG. 9, in this embodiment, a voltage detection value or a voltage command value may be used in addition to the current detection value. When the activation / acceleration failure is detected, the speed command resetting unit 124 returns the speed command value to the initial value in order to restart. Further, the phase correction value resetting unit 122 resets the phase correction value (including the number of times of changing the value and the phase) to a value different from that when the activation fails. Further, the current command resetting unit 123 resets the current command value (including the value and the number of times of change) to a value different from that when the activation fails. The value may be changed by at least one of the phase correction value and the current command value. For example, by making the phase correction value smaller than the previous value, the rotation becomes smoother as in the second embodiment. Further, if the current command value is made larger than the previous value, the torque becomes larger and it is easy to start and accelerate.

It is a block diagram of the synchronous motor drive device of Example 1. It is a figure which shows the relationship between phase difference (DELTA) phi and generated torque regarding Example 1. FIG. It is a figure which shows the relationship of It ^* , (omega ⁾ r ^* , (DELTA ⁾ (theta) in connection with Example 1. FIG. It is a figure which shows the relationship of It ^* , (omega ⁾ r ^* , (DELTA ⁾ (theta) in connection with Example 3. FIG. It is a figure which shows the relationship of It ^* , (omega ⁾ r ^* , (DELTA ⁾ (theta) in connection with Example 4. FIG. It is a figure which shows the relationship of It ^* , (omega ⁾ r ^* , (DELTA ⁾ (theta) in connection with Example 5. FIG. FIG. 10 is a configuration diagram of a synchronous motor driving device according to a sixth embodiment. FIG. 10 is a configuration diagram of a synchronous motor driving device according to a seventh embodiment. FIG. 10 is a configuration diagram of a synchronous motor drive device according to an eighth embodiment. It is a block diagram of the induction motor drive device of a prior art. It is a figure which shows the reference axis of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Torque command value setting part, 2 ... Phase correction value setting part, 3 ... Frequency correction value calculating part, 4 ... Coordinate conversion part, 5 ... Integration part, 11 ... Current command switching part, 101 ... Power converter part, 102 DESCRIPTION OF SYMBOLS ... Synchronous motor, 103 ... Speed control part, 104 ... Notch filter part, 105 ... Current command calculating part, 106 ... Current control part, 107 ... Current detector, 108 ... Voltage detector, 109 ... Phase calculating part, 110 ... Harmonic Wave voltage detector, 111 ... speed error detector, 112 ... speed estimator, 113 ... harmonic current generator, 121 ... activation availability detector, 122 ... phase correction value resetter, 123 ... current command resetter, 124: Speed command resetting unit.

Claims (18)

In the motor drive device that controls the magnitude, frequency, and phase of the output voltage and drives the synchronous motor,
When starting the synchronous motor, add a predetermined phase correction value to the phase,
An electric motor drive device that changes the phase correction value at least once, calculates the correction value of the frequency based on a detected value of the output current, and corrects the frequency of the output voltage. In claim 1,
When starting the synchronous motor,
An electric motor drive device characterized in that an initial value of a speed command value is set to a predetermined value, and the phase and frequency are corrected before the speed command value is increased. In claim 1,
When changing the predetermined phase correction value, the motor driving device increases the phase in the normal rotation direction of the synchronous motor. In claim 1,
When the predetermined phase correction value is changed for the first time, the time for setting the first phase correction value is shorter than the time for setting the phase correction value after change. In claim 1,
The motor drive device according to claim 1, wherein a torque current command value of the synchronous motor is a predetermined value that does not exceed a rated current value of the synchronous motor. In claim 5,
An electric motor drive device characterized in that a torque current command value before the predetermined phase correction value is first changed is smaller than a torque current command value after the predetermined phase correction value is changed. In claim 5,
Before changing the predetermined phase correction value, the torque current command value is set to zero at a predetermined rate so that the torque current command value becomes zero while the predetermined phase correction value is changed. After the phase correction value is changed, the torque current command value is returned to the original value at a predetermined rate. In the motor drive device that controls the magnitude, frequency, and phase of the output voltage and drives the synchronous motor,
When starting the synchronous motor, add a predetermined phase correction value to the phase,
The predetermined phase correction value is changed once or more, and a phase correction value calculated based on a detected value of output current is added to the phase. In claim 8,
When starting the synchronous motor,
An electric motor drive device characterized in that the phase correction is performed before the speed command value is set to a predetermined value and the speed command value is increased. In claim 8,
When changing the predetermined phase correction value, the motor driving device increases the phase in the normal rotation direction of the synchronous motor. In claim 8,
When the predetermined phase correction value is changed for the first time, the time for setting the first phase correction value is shorter than the time for setting the phase correction value after change. In claim 8,
The motor drive device according to claim 1, wherein a torque current command value of the synchronous motor is a predetermined value that does not exceed a rated current value of the synchronous motor. In claim 12,
An electric motor drive device characterized in that a torque current command value before the predetermined phase correction value is first changed is smaller than a torque current command value after the predetermined phase correction value is changed. In claim 12,
Before changing the predetermined phase correction value, the torque current command value is set to zero at a predetermined rate so that the torque current command value becomes zero while the predetermined phase correction value is changed. After the phase correction value is changed, the torque current command value is returned to the original value at a predetermined rate. In a motor drive device that sets a t-axis current command value parallel to a torque current and an m-axis current command value perpendicular to the t-axis, controls the magnitude, frequency, and phase of the output voltage and drives a synchronous motor ,
At the time of starting the synchronous motor, the value of the t-axis current command value and the m-axis current command value is changed at least once or more, and the frequency correction value is calculated based on the detected value of the output current, An electric motor drive device that corrects a frequency. In claim 15,
When starting the synchronous motor,
The initial value of the speed command value is set to a predetermined value, and the t-axis current command value and the m-axis current command value are changed and the frequency is corrected before the speed command value is increased. An electric motor drive device. In a motor drive device that sets a t-axis current command value parallel to a torque current and an m-axis current command value perpendicular to the t-axis, controls the magnitude, frequency, and phase of the output voltage and drives a synchronous motor ,
At the time of starting the synchronous motor, the t-axis current command value and the m-axis current command value are changed at least once or more, and the phase correction value calculated based on the detected output current is set to the phase An electric motor drive device characterized by being added to the motor drive device. In claim 17,
When the synchronous motor is started, the speed command value initial value is set to a predetermined value, and the t-axis current command value and the m-axis current command value are changed before the speed command value is increased, and the current detection value An electric motor drive device that performs phase correction that adds a phase correction value calculated based on the above to the phase.

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