JP2015126598A - Motor control device and motor control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stability of an activation period of a synchronization motor.SOLUTION: A motor control device 100 comprises: a magnetic flux estimation part 108 estimating a motor magnetic flux; and a switching part 133 performing control of switching from an activation synchronous operation of supplying a synchronization current required to activate a synchronous motor 102 to the synchronous motor 102, to a position sensorless operation executed while referring to the estimated phase of the motor magnetic flux and of setting a command amplitude so that an amplitude of the motor magnetic flux converges to a target amplitude, independently of the phase of the motor magnetic flux. The motor control device 100 adjusts at least one of the synchronization current before the switching of the operation mode by the switching part 133 and the command amplitude after the switching of the operation mode by the switching part 133, to reduce a difference between the amplitude of the motor magnetic flux and the target amplitude consecutively or in a stepwise manner before or after the switching of the operation mode by the switching part 133.

Description

  The present invention relates to a motor control device and a motor control method.

  Conventionally, direct torque control (DTC) is known as a method for driving a synchronous motor. In general direct torque control, first, the phase current and phase voltage of a synchronous motor connected to an inverter are detected. Next, the armature flux linkage and torque of the synchronous motor are obtained from the phase current and phase voltage. Next, a command magnetic flux vector is obtained from the obtained torque, command torque, command amplitude, and armature linkage magnetic flux phase. The command amplitude is an amplitude that the amplitude of the armature flux linkage should follow. The command torque and the command amplitude are obtained by a speed control device, for example. Next, a voltage vector to be applied from the inverter to the synchronous motor is determined from the command magnetic flux vector and the armature linkage magnetic flux. Next, switching of the inverter is controlled so that the determined voltage vector is applied to the synchronous motor.

  The drive algorithm for direct torque control is simple. Further, position sensors such as encoders and resolvers can be omitted.

  Non-Patent Document 1 describes an example of a motor control device using direct torque control.

Inoue and three others, "Torque ripple reduction, and flux-weakening control for interior permanent magnet synchronous motor based on direct torque control", 2006 Electric Proceedings of National Conference of the Society, The Institute of Electrical Engineers of Japan, March 2006, 4th volume, 4-106, p. 166

  The conventional motor control device using direct torque control has room for improving the stability in the start-up period (period including the start time). The present invention has been made in view of such circumstances.

That is, this disclosure
A magnetic flux estimator for estimating a motor magnetic flux that is a magnetic flux of the synchronous motor;
Regardless of the phase of the motor magnetic flux, while referring to the phase of the motor magnetic flux estimated by the magnetic flux estimator from the start synchronous operation for supplying the synchronous current necessary for starting the synchronous motor to the synchronous motor A position sensorless operation that is executed, and a switching unit that controls switching to a position sensorless operation that sets a command amplitude that the amplitude of the motor magnetic flux should follow so that the amplitude of the motor magnetic flux converges to a target amplitude; ,
With
By adjusting at least one of the synchronous current before switching of the operation mode by the switching unit and the command amplitude after switching of the operation mode by the switching unit, switching of the operation mode by the switching unit is performed. A motor control device is provided that reduces the difference between the amplitude of the motor magnetic flux and the target amplitude continuously or stepwise before or after.

  According to the motor control device described above, the stability during the startup period of the synchronous motor is improved.

Block diagram of the motor control device of the first embodiment Diagram for explaining dq coordinate system and αβ coordinate system The block diagram of the synchronous control part of 1st Embodiment The block diagram of the position sensorless control part of 1st Embodiment The figure for explaining the method of specifying the estimated magnetic flux when starting synchronous operation is executed The block diagram of the switching part of 1st Embodiment Configuration diagram of the PWM inverter of the first embodiment Time chart for explaining a method of starting a synchronous motor in the first embodiment The graph which shows the result of the simulation for explaining the problem at the time of starting a synchronous motor using the conventional motor control device A graph obtained by enlarging a part of the graph shown in FIG. 9A The graph which shows the result of the simulation for confirming the effect of 1st Embodiment The graph which expanded a part of graph shown to FIG. 10A Block diagram of motor control apparatus of second embodiment The block diagram of the position sensorless control part of 2nd Embodiment The block diagram of the synchronous control part of 2nd Embodiment The flowchart which shows the control method of the synchronous control part of 2nd Embodiment Time chart for explaining a method of starting a synchronous motor in the second embodiment The graph which shows the result of the simulation for confirming the effect of 2nd Embodiment The graph which expanded a part of graph shown to FIG. 16A

  In position sensorless operation using direct torque control or the like, the magnetic flux (motor magnetic flux) applied to the synchronous motor is estimated. The greater the difference (amplitude deviation) between the command amplitude and the estimated motor magnetic flux amplitude, the greater the voltage applied to the synchronous motor.

  In the position sensorless operation as described above, the motor magnetic flux cannot be estimated with sufficient accuracy when the rotational speed of the synchronous motor is low. For this reason, in the starting period of a synchronous motor, it is possible to increase the rotation speed of a synchronous motor by synchronous operation and to switch to position sensorless operation after that. When starting the synchronous motor in this way, the motor magnetic flux is estimated even during the period in which the synchronous operation is performed, and the difference between the command amplitude and the motor magnetic flux amplitude estimated by the synchronous operation is changed when the operation mode is switched. Can be used as a temporary amplitude deviation.

  In typical synchronous operation, a current (synchronous current) that is significantly larger than the current supplied to the synchronous motor during position sensorless operation is supplied to the synchronous motor. This means that the amplitude of the motor magnetic flux estimated during the period in which the synchronous operation is performed is significantly larger than the command amplitude used in the position sensorless operation. For this reason, the temporary amplitude deviation described above is significantly larger than the amplitude deviation in the steady state of the position sensorless operation. As a result, a remarkably large voltage is applied to the synchronous motor (voltage surge occurs) when the operation mode is switched. Further, with the occurrence of the voltage surge, torque pulsation occurs or the synchronous motor steps out.

  In view of such circumstances, the present inventor has studied to improve the stability of the synchronous motor during the startup period.

That is, the first aspect of the present disclosure is:
A magnetic flux estimator for estimating a motor magnetic flux that is a magnetic flux of the synchronous motor;
Regardless of the phase of the motor magnetic flux, while referring to the phase of the motor magnetic flux estimated by the magnetic flux estimator from the start synchronous operation for supplying the synchronous current necessary for starting the synchronous motor to the synchronous motor A position sensorless operation that is executed, and a switching unit that controls switching to a position sensorless operation that sets a command amplitude that the amplitude of the motor magnetic flux should follow so that the amplitude of the motor magnetic flux converges to a target amplitude; ,
With
(I) The synchronous current is decreased continuously or stepwise before switching the operation mode by the switching unit, and / or (ii) the amplitude of the motor magnetic flux at the time of switching the operation mode by the switching unit The command amplitude is set so that the difference between the amplitude of the motor magnetic flux and the command amplitude is smaller than the difference from the target amplitude, and then the command amplitude is made to approach the target amplitude continuously or stepwise. A motor control device is provided.

  According to the 1st aspect, generation | occurrence | production of the voltage surge at the time of switching of an operation mode can be suppressed.

  According to a second aspect of the present disclosure, in addition to the first aspect, the motor control device causes the motor magnetic flux amplitude and the command amplitude to be larger than the difference between the motor magnetic flux amplitude and the target amplitude when the operation mode is switched. The motor control device includes a delay filter that sets the command amplitude so that the difference between the command amplitude and the target amplitude gradually approaches the target amplitude.

  According to a third aspect of the present disclosure, in addition to the second aspect, the delay filter provides a motor control device that is a low-pass filter or a filter based on a weight function.

  If the motor control device of the second mode or the third mode is used, the difference (temporary amplitude deviation) between the command amplitude at the time of switching the operation mode and the amplitude of the motor magnetic flux estimated by the synchronous operation can be reduced. Thereby, generation | occurrence | production of the voltage surge at the time of switching of an operation mode is suppressed. Further, according to the motor control device of the second aspect or the third aspect, when the position sensorless operation starts, the amplitude of the motor magnetic flux gradually approaches the target amplitude. Thereby, generation | occurrence | production of the voltage surge at the time of making the amplitude of a motor magnetic flux approach target amplitude is suppressed.

  According to a fourth aspect of the present disclosure, in addition to any one of the first to third aspects, the motor control device reduces the synchronous current continuously or stepwise before switching the operation mode. I will provide a. If the motor control device according to the fourth aspect is used, the amplitude of the motor magnetic flux decreases before the operation mode is switched. For this reason, the above-mentioned temporary amplitude deviation can be reduced. Therefore, the occurrence of a voltage surge when switching the operation mode is suppressed.

  According to a fifth aspect of the present disclosure, in addition to any one of the first to fourth aspects, the motor control device includes: a synchronous control unit that executes the startup synchronous operation; and a position sensorless control unit that executes the position sensorless operation. And the synchronous control unit converts a phase current on the three-phase AC coordinate in the synchronous motor into a first axial current on the first two-phase coordinate. And a first voltage command calculation unit that generates a first axis voltage on the first two-phase coordinates corresponding to a voltage vector to be applied to the synchronous motor from the first axis current. The position sensorless control unit includes a second three-phase two-phase coordinate conversion unit that converts the phase current into a second axis current on a second two-phase coordinate; the second axis current; From the second axis voltage on the second two-phase coordinate corresponding to the voltage vector, the mode From the magnetic flux estimation unit that estimates magnetic flux, the second shaft current, and the estimated motor magnetic flux, the torque calculation unit that estimates the motor torque, and the estimated motor torque and the motor torque follow. A magnetic flux command calculation unit that specifies a command magnetic flux vector that the motor magnetic flux should follow from the torque deviation between the command torque to be performed, the estimated phase of the motor magnetic flux, and the command amplitude; and the command magnetic flux A second voltage command calculation unit that specifies the second shaft voltage from a magnetic flux deviation between the vector and the estimated motor magnetic flux, and the motor control device executes the start-up synchronous operation The motor magnetic flux is estimated using the magnetic flux estimator in the position sensorless controller based on the second axial current and the first axial voltage during the current period. To provide a motor controller configured to.

  The motor control device of the fifth aspect can be simply configured. In addition, you may comprise the motor control apparatus using only the one part structure of the motor control apparatus of a 5th aspect. For example, the motor control device may be a device including the above-described synchronization control unit. The motor control device may be a device including the above-described position sensorless control unit. The magnetic flux estimation unit may belong to the synchronization control unit, may belong to the position sensorless unit, or may be independent of these. The first two-phase coordinates and the second two-phase coordinates may be the same or different. When the motor control device of the fifth aspect is realized by software, each component of the motor control device is not clearly distinguished.

The sixth aspect of the present disclosure is:
Estimating a motor magnetic flux that is a magnetic flux of the synchronous motor;
Position sensorless, which is executed while referring to the estimated phase of the motor magnetic flux from the start synchronous operation that supplies the synchronous motor with the synchronous current necessary for starting the synchronous motor regardless of the phase of the motor magnetic flux. A step of switching the operation mode to a position sensorless operation for setting a command amplitude that the amplitude of the motor magnetic flux should follow so that the amplitude of the motor magnetic flux converges to a target amplitude;
Including
i) decreasing the synchronous current continuously or stepwise before switching the operation mode, and / or (ii) from the difference between the amplitude of the motor magnetic flux and the target amplitude at the time of switching the operation mode Also provided is a motor control method in which the command amplitude is set so that the difference between the amplitude of the motor magnetic flux and the command amplitude is small, and then the command amplitude is made to approach the target amplitude continuously or stepwise.

The seventh aspect of the present disclosure is:
A magnetic flux estimator for estimating a motor magnetic flux that is a magnetic flux of the synchronous motor;
Regardless of the phase of the motor magnetic flux, while referring to the phase of the motor magnetic flux estimated by the magnetic flux estimator from the start synchronous operation for supplying the synchronous current necessary for starting the synchronous motor to the synchronous motor A position sensorless operation that is executed, and a switching unit that controls switching to a position sensorless operation that sets a command amplitude that the amplitude of the motor magnetic flux should follow so that the amplitude of the motor magnetic flux converges to a target amplitude; ,
With
By adjusting at least one of the synchronous current before switching of the operation mode by the switching unit and the command amplitude after switching of the operation mode by the switching unit, switching of the operation mode by the switching unit is performed. Provided is a motor control device that reduces the difference between the amplitude of the motor magnetic flux and the target amplitude continuously or stepwise before or after.

  According to the sixth aspect and the seventh aspect, the same effect as that obtained by the first aspect can be obtained.

  The technology related to the motor control device can be applied to a motor control method. The technology related to the motor control method can be applied to a motor control device.

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

(First embodiment)
As illustrated in FIG. 1, the motor control device 100 includes a first current sensor 105 a, a second current sensor 105 b, a synchronization control unit 131, a position sensorless control unit 132, a switching unit 133, and a duty generation unit 103. The motor control device 100 is connected to the PWM inverter 104 and the synchronous motor 102.

  The synchronization control unit 131 is configured to execute the startup synchronous operation of the synchronous motor 102. The position sensorless control unit 132 is configured to execute a position sensorless operation of the synchronous motor 102. The start-up synchronous operation is an operation for ensuring that the rotational speed (rotational speed) of the rotor of the synchronous motor 102 matches the rotational speed (synchronous speed) of the motor magnetic flux applied to the synchronous motor 102. In the present embodiment, the rotational speed of the rotor of the synchronous motor 102 matches the synchronous speed even during the period when the position sensorless operation is being performed. The position sensorless operation is an operation that does not use a position sensor such as an encoder or a resolver. However, in the present embodiment, the position sensor is not used even during the period in which the start-up synchronous operation is performed. In the present specification, for convenience of explanation, an operation for controlling the motor magnetic flux without using the estimated phase of the motor magnetic flux is referred to as a start synchronous operation. An operation for controlling the motor magnetic flux using the estimated phase of the motor magnetic flux is referred to as a position sensorless operation. The motor magnetic flux is a concept including both the armature linkage magnetic flux on the three-phase AC coordinates applied to the synchronous motor 102 and the magnetic flux obtained by coordinate conversion of the armature linkage flux. In this specification, “amplitude” may simply refer to magnitude (absolute value).

  Some or all of the elements of the motor control device 100 may be provided by a control application executed in a DSP (Digital Signal Processor) or a microcomputer. The DSP or microcomputer may include peripheral devices such as a core, a memory, an A / D conversion circuit, and a communication port. Further, some or all of the elements of the motor control device 100 may be configured by a logic circuit.

(Outline of control by the motor control device 100)
The motor control device 100 generates the duties D _u , D _v , and D _w from the command rotation speed ω _ref ^* and the phase currents i _u and i _w . The PWM inverter 104 generates voltage vectors v _u , v _v , v _w to be applied to the synchronous motor 102 from the duties D _u , D _v , D _w . The command rotational speed ω _ref ^* is given to the motor control device 100 from the host control device. The command rotational speed ω _ref ^* represents the rotational speed that the synchronous motor 102 should follow.

An outline of the operation of the motor control device 100 will be described with reference to FIG. The phase currents i _u and i _w are detected by the current sensors 105a and 105b. When the start synchronous operation is executed, the command voltage vectors v _1u ^* , v _1v ^* , v _1w ^* are generated from the command rotation speed ω _ref ^* and the phase currents i _u , i _w by the synchronous control unit 131. The Each component of the command voltage vectors v _1u ^* , v _1v ^* , v _1w ^* corresponds to a U-phase voltage, a V-phase voltage, and a W-phase voltage on a three-phase AC coordinate, respectively. When the position sensorless operation is being executed, the position sensorless control unit 132 generates the command voltage vectors v _2u ^* , v _2v ^* , v _2w ^* from the command rotation speed ω _ref ^* and the phase currents i _u , i _w. Is done. Each component of the command voltage vectors _v2u ^* , _v2v ^* , _v2w ^* corresponds to a U-phase voltage, a V-phase voltage, and a W-phase voltage on a three-phase AC coordinate, respectively. When the start-up synchronous operation is being executed, the command voltage vectors v _1u ^* , v _1v ^* , v _1w ^* are selected as the command voltage vectors v _u ^* , v _v ^* , v _w ^* by the switching unit 133, Is output. While running position sensorless operation, the switching unit 133, the command voltage vector ^{_{v 2u *, v 2v *,}} v 2w * is, the command voltage vector ^{_{v u *, v v *,}} v is selected as _w ^*, Is output. The duty generation unit 103, the command voltage vector _{v u} ^*, v v ^*, the v _w ^*, the duty D _u, D _v, D _w is generated. Duty D _u, D _v, D _w is inputted to the PWM inverter 104. By such control, the synchronous motor 102 is controlled such that the rotational speed follows the command rotational speed ω _ref ^* .

  Hereinafter, the motor control device 100 may be described based on dq coordinates (first two-phase coordinates). Further, the motor control device 100 may be described based on α-β coordinates (second two-phase coordinates). FIG. 2 shows dq coordinates and α-β coordinates. The α-β coordinates are fixed coordinates. The α-β coordinates are also referred to as stationary coordinates and AC coordinates. The α axis is set as an axis extending in the same direction as the U axis (omitted in FIG. 2). The dq coordinates are rotational coordinates. θ is the advance angle of the d-axis viewed from the U-axis. θ is also referred to as the rotor position.

(Outline of control by the synchronization control unit 131)
The synchronization control unit 131 executes a start-up synchronous operation for supplying the synchronization motor 102 with a synchronization current necessary to start up the synchronization motor 102 regardless of the phase of the motor magnetic flux.

  As shown in FIG. 3, the synchronization control unit 131 includes a synchronization current command unit 124, a voltage command calculation unit (first voltage command calculation unit) 125, a d, q / u, v, w conversion unit (first 2 Phase three-phase coordinate conversion unit) 126, u, w / d, q conversion unit (first three-phase two-phase coordinate conversion unit) 127 and integrator 128.

In the synchronization control unit 131, the rotor position θ is specified by the integrator 128 from the command rotational speed ω _ref ^* . The rotor position θ represents the position of the rotor of the synchronous motor 102. The rotor position θ corresponds to the phase of the motor magnetic flux. The u, w / d, q conversion unit 127 converts the phase currents i _u , i _w into axial currents i _d , i _q (first axial current). In this conversion, the rotor position θ is used. The shaft currents i _d and i _q are a summary of the d-axis current i _d and the q-axis current i _q on the dq coordinate of the synchronous motor 102. The synchronous current command unit 124 generates command axis currents i _d ^* , i _q ^* . The command shaft currents i _d ^* and i _q ^* are shaft currents that the shaft currents i _d and i _q should follow. The command axis currents i _d ^* and i _q ^* collectively describe the d axis command axis current i _d ^* and the q axis command axis current i _q ^* on the dq coordinate of the synchronous motor 102. The voltage command calculation unit 125 generates command axis voltages v _d ^* , v _q ^* (first axis voltage) from the command axis currents i _d ^* , i _q ^* and the axis currents i _d , i _q . The command axis voltages v _d ^* and v _q ^* collectively describe the d axis command voltage v _d ^* and the q axis command voltage v _q ^* on the dq coordinate of the synchronous motor 102. d, q / u, v, by w conversion unit 126, the command-axis voltage v _d ^*, v _q ^* is the command voltage vector _{v 1u} ^*, v _1v ^*, it is converted to v _{1 w} ^*. In this conversion, the rotor position θ is used. In the start-up synchronous operation, the rotation speed follows the command rotation speed ω _ref ^* and the shaft currents i _d and i _q follow the command shaft currents i _d ^* and i _q ^* by such control.

(Outline of control by position sensorless control unit 132)
The position sensorless control unit 132 performs position sensorless operation for setting the command amplitude so that the amplitude of the motor magnetic flux converges to the target amplitude. The position sensorless operation is executed with reference to the phase of the motor magnetic flux estimated by the magnetic flux calculation unit (magnetic flux estimation unit). The target amplitude is the amplitude that the motor magnetic flux amplitude should finally reach. The command amplitude is an amplitude that the amplitude of the motor magnetic flux should follow.

  As shown in FIG. 4, the position sensorless control unit 132 includes a u, w / α, β conversion unit (second three-phase two-phase coordinate conversion unit) 106, a voltage command calculation unit (second voltage command calculation unit). 107, magnetic flux calculation unit (magnetic flux estimation unit) 108, torque calculation unit 109, speed / position calculation unit 110, torque command calculation unit 121, torque deviation calculation unit 111, amplitude command generation unit 122, amplitude command correction unit 123, magnetic flux command A calculation unit 112, an α-axis magnetic flux deviation calculation unit 113a, a β-axis magnetic flux deviation calculation unit 113b, and an α, β / u, v, w conversion unit (second two-phase three-phase coordinate conversion unit) 114 are provided.

In the position sensorless control unit 132, the u, w / α, β conversion unit 106 converts the phase currents i _u , i _w into axial currents i _α , i _β (second axial current). The axial currents i _α and i _β are collectively described as the α-axis current i _α and the β-axis current i _β on the α-β coordinate of the synchronous motor 102. The magnetic flux calculation unit 108 estimates the motor magnetic flux (estimated magnetic flux Ψ _s is obtained). The α-axis component and β-axis component of the estimated magnetic flux ψ _s are described as estimated magnetic fluxes ψ _α and ψ _β , respectively. The speed-position calculating unit 110, the estimated magnetic flux [psi _s, synchronous speed and motor flux of the phase of the motor 102 is estimated (phase theta _s estimated rotation speed omega _r and the estimated magnetic flux [psi _s is determined). The torque calculator 109 estimates the motor torque from the estimated magnetic flux Ψ _s and the shaft currents i _α and i _β (the estimated torque _Te is obtained). The torque command calculation unit 121 generates a command torque T _e ^* from the estimated rotation speed ω _r and the command rotation speed ω _ref ^* . The command torque _Te ^* represents the torque that the motor torque should follow. The amplitude command generating unit 122, the command torque T _e ^* from the command amplitude | Ψ _s ^* | is generated. The amplitude command correcting unit 123 corrects the command amplitude | Ψ _s ^* | to the command amplitude | Ψ _s ^** |. A torque deviation calculation unit 111 obtains a deviation (torque deviation) ΔT between the estimated torque _Te and the command torque _Te ^* . The magnetic flux command calculation unit 112 obtains the command magnetic flux vector ψ _s ^* from the command amplitude | ψ _s ^** |, the torque deviation ΔT, and the phase θ _s . The α-axis component and β-axis component of the command magnetic flux vector ψ _s ^* are described as α-axis command amplitude ψ _α ^* and β-axis command amplitude ψ _β ^* , respectively. the alpha-axis magnetic flux deviation calculation unit 113a, alpha axis command amplitude [psi _alpha ^* and the estimated flux [psi _alpha and deviation (the magnetic flux deviation) [Delta] [Psi] _alpha is obtained. the beta-axis magnetic flux deviation calculation unit 113b, beta axis command amplitude [psi _beta ^* and the estimated flux [psi _beta and deviation (the magnetic flux deviation) [Delta] [Psi] _beta is obtained. The command command calculation unit 107 obtains command shaft voltages v _α ^* and v _β ^* (second shaft voltages) from the magnetic flux deviations ΔΨ _α and ΔΨ _β and the shaft currents i _α and i _β . The command axis voltages v _α ^* and v _β ^* are a summary of the α axis command voltage v _α ^* and the β axis command voltage v _β ^* on the α-β coordinate of the synchronous motor 102. alpha, beta / u, v, by w conversion unit 114, the command-axis voltage v α ^_*, v β ^* are command voltage vector v _2u ^*, v _2v ^*, is converted into v _2w ^*.

In the position sensorless operation, by such control, the rotation speed follows the command rotation speed ω _ref ^* , the motor torque follows the command torque T _e ^* , and the motor magnetic flux amplitude changes to the command amplitude | Ψ _s ^** | The motor magnetic flux follows the command magnetic flux vector Ψ _s ^* . Further, the amplitude of the motor magnetic flux finally converges to the command amplitude | Ψ _s ^* |. As described above, when the expression “the position sensorless control unit 132 executes the position sensorless operation for setting the command amplitude so that the amplitude of the motor magnetic flux converges to the target amplitude”, the “target amplitude” This corresponds to the command amplitude | Ψ _s ^* |. Considering this, hereinafter, the command amplitude | Ψ _s ^* | may be referred to as a target amplitude | Ψ _s ^* |. When expressed in this way, the “command amplitude” corresponds to the command amplitude | Ψ _s ^** |.

When the position sensorless operation is being executed, as shown in FIG. 4, the estimated magnetic flux Ψ _{s is} calculated from the axial currents i _α and i _β and the command axial voltages v _α ^* and v _β ^* using the magnetic flux calculation unit 108. Ask for. Further, when the start-up synchronous operation is being executed, the estimated magnetic flux Ψ is calculated using the magnetic flux calculation unit 108 based on the shaft currents i _α , i _β and the command voltage vectors v _1u ^* , v _1v ^* , v _1w ^*. _{Find s} . Specifically, as shown in FIG. 5, the command voltage vectors v _1u ^* , v _1v ^{* are} obtained using a u, v, w / α, β converter (third two-phase three-phase coordinate converter) 150 ^. , V _1w ^* are converted into reference shaft voltages v _α ′, v _β ′. Thereafter, the magnetic flux calculation unit 108 obtains the estimated magnetic flux Ψ _s from the axial currents i _α and i _β and the reference axial voltages v _α ′ and v _β ′.

“Start-up synchronous operation for supplying synchronous current to the synchronous motor 102” is not an expression intended to use the command axis current in the start-up synchronous operation. The start-up synchronous operation can be executed without using the command axis current. For example, a command axis voltage may be used. Since details of the start-up synchronous operation in this case are obvious to those skilled in the art, description thereof is omitted. In short, in the start synchronous operation of the present embodiment, a command that is not the command torque _Te ^* is used. Then, when the operation is switched to the position sensorless operation, control using the command torque _Te ^* is started.

In this specification, the shaft currents i _d and _iq mean current values transmitted as information, not currents actually flowing through the synchronous motor 102. Command shaft currents i _d ^* , i _q ^* , command shaft voltages v _d ^* , v _q ^* , command rotational speed ω _ref ^* , rotor position θ, and command voltage vectors v _1u ^* , v _1v ^* , v _1w ^* are also used as information. Means the value to be transmitted. Shaft currents i _α , i _β , command shaft voltages v _α ^* , v _β ^* , estimated magnetic flux Ψ _s , phase θ _s , estimated torque _Te , command torque _Te ^* , command amplitude | Ψ _s ^* | (target amplitude | Ψ _s ^* |), command amplitude | Ψ _s ^** |, command magnetic flux vector Ψ _s ^* , command voltage vectors v _2u ^* , v _2v ^* , v _2w ^* , command voltage vectors v _u ^* , v _v ^* , v _w ^The same applies to ^{* and the} like.

  The components of the synchronization control unit 131 shown in FIG. 3 will be described below.

(Integrator 128)
The integrator 128 obtains an instruction rotational speed omega _ref ^*, accumulating (integrating) the command rotation speed omega _ref ^*. In this way, the integrator 128 determines the rotor position θ. Specifically, the integrator 128 calculates the rotor position θ according to the equation (1). s is a Laplace operator. The integrator 128 is a known integrator.

(U, w / d, q converter 127)
The u, w / d, q conversion unit 127 acquires the rotor position θ and converts the phase currents i _u and i _w into the shaft currents i _d and i _q using the rotor position θ. Specifically, the u, w / d, q conversion unit 127 converts the phase currents i _u , i _w into the axial currents i _d , i _{q according} to the equations (2) and (3), and the axial currents i _d , i _q is output.

(Synchronous current command section 124)
Synchronous current command section 124, the command-axis current i _d ^*, generates the i _q ^*, the command-axis current i _d ^*, and outputs the i _q ^*. The command axis currents i _d ^* and i _q ^* correspond to the synchronous current to be supplied to the synchronous motor 102. In the present embodiment, the command axis currents i _d ^* and i _q ^* are predetermined currents. The command axis currents i _d ^* and i _q ^* are currents having a constant magnitude. In the present embodiment, the d-axis command axis current i _d ^* is zero. Specifically, the synchronization current command section 124, the command-axis current i _d ^* by equation (4), to generate the i _q ^*, the command-axis current i _d ^*, and outputs the i _q ^*.

(Voltage command calculation unit 125)
The voltage command calculation unit 125 generates command shaft voltages v _d ^* and v _q ^* from the shaft currents i _d and i _q and the command shaft currents i _d ^* and i _q ^* . Command-axis voltage v _d ^*, v _q ^*, the axis current i _d, i _q is the command-axis current i _d ^*, are identified to follow the i _q ^*. Specifically, the voltage command calculation unit 125 generates and outputs command axis voltages v _d ^* and v _q ^{* according} to equations (5) and (6). K _cdP and K _cqP in equations (5) and (6) are proportional gains. K _cdI and K _cqI are integral gains. The voltage command calculation unit 125 is a known PI compensator.

(D, q / u, v, w converter 126)
d, q / u, v, w conversion unit 126 uses the rotor position theta, command-axis voltage v _d ^*, v _q ^* the command voltage vector ^{_{v 1u *, v 1v *,}} v is converted to _{1 w} ^*. Specifically transformation, d, q / u, v , w conversion unit 126, the command-axis voltage v _d ^* by the formula (7), v _q ^* the command voltage vector ^{_{v 1u *, v 1v *,}} v to _{1 w} ^* and, the command voltage vector ^{_{v 1u *, v 1v *,}} v outputs a _1w ^*.

Note that the synchronization control unit 131 can be configured such that the rotor position θ can be obtained by a method other than integrating the command rotational speed ω _ref ^* by the integrator 128. The rotor position θ may be a value given from the outside. For example, the rotor position θ can be given to the synchronization control unit 131 from the host control device.

  The components of the position sensorless control unit 132 shown in FIG. 4 will be described below.

(U, w / α, β converter 106)
The u, w / α, β converter 106 converts the phase currents i _u , i _w into axial currents i _α , i _β . Specifically, the u, w / α, β conversion unit 106 converts the phase currents i _u , i _w into the axial currents i _α , i _β by the equations (8), (9), and the axial current i _α. , I _β .

(Magnetic flux calculator 108)
When performing the position sensorless operation, the magnetic flux calculation unit 108 calculates the estimated magnetic flux ψ _s (estimated magnetic flux ψ _α , ψ _β ) from the shaft currents i _α and i _β and the command shaft voltages v _α ^* and v _β ^*. Ask for. Specifically, the magnetic flux calculation unit 108 obtains the absolute values | Ψ _s | of the estimated magnetic fluxes ψ _α , Ψ _β , and the estimated magnetic flux ψ _s using the equations (10), (11), and (12). In equations (10) and (11), ψ _{α | t = 0} and ψ _{β | t = 0} are initial values of the estimated magnetic fluxes ψ _α and ψ _β , respectively. R in the equations (10) and (11) is the winding resistance of the synchronous motor 102. When the magnetic flux calculation unit 108 is incorporated in a digital control device such as a DSP or a microcomputer, the integrator required for the calculation in the equations (10) and (11) can be configured as a discrete system. In this case, a value derived from the current control cycle may be added to or subtracted from the estimated magnetic fluxes ψ _α , ψ _β before one control cycle.

The magnetic flux calculation unit 108 is also used when the start-up synchronous operation is being executed. In this case, the magnetic flux calculation unit 108 cooperates with the u, v, w / α, β conversion unit 150 (FIG. 5), and the axial currents i _α , i _β and the command voltage vectors v _1u ^* , v _1v ^* , Estimated magnetic fluxes Ψ _α and Ψ _β are obtained based on v _1w ^* . Specifically, the u, v, w / α, β conversion unit 150 uses the equations (13) and (14) to convert the command voltage vectors v _1u ^* , v _1v ^* , v _1w ^* into reference shaft voltages. Convert to v _α ′, v _β ′. The magnetic flux calculator 108 obtains estimated magnetic fluxes ψ _α , ψ _β from the shaft currents i _α , i _β and the reference shaft voltages v _α ′, v _β ′. When the estimated magnetic fluxes Ψ _α and Ψ _β are obtained, an expression in which the command axis voltages v _α ^* and v _β ^* in the expressions (10) and (11) are replaced with reference axis voltages v _α ′ and v _β ′ is obtained. Used. The shaft currents i _α and i _β are specified from the current sensors 105 a and 105 b and the u, w / α and β conversion unit 106 as in the case where the position sensorless operation is performed.

(Torque calculation unit 109)
Torque computing section 109, the axial current i _alpha, i _beta and the estimated magnetic flux [psi _s (estimated magnetic flux Ψ _α, Ψ _β) obtaining the estimated torque T _e from. Specifically, the torque calculation unit 109, using Equation (15) determines the estimated torque T _e. P _n in equation (15) is the _number of pole pairs of the synchronous motor 102.

(Speed / position calculation unit 110)
The speed / position calculation unit 110 obtains the phase θ _s of the estimated magnetic flux ψ _s from the estimated magnetic flux ψ _s (estimated magnetic flux ψ _α , ψ _β ). Specifically, the speed / position calculation unit 110 obtains the phase θ _s of the estimated magnetic flux Ψ _s by Expression (16). Further, the speed / position calculation unit 110 uses the phase θ _s (n) obtained in the current control cycle and the phase θ _s (n−1) obtained in the previous control cycle according to the equation (17). The estimated rotational speed ω _r is obtained. The speed / position calculation unit 110 is a known phase estimator. Here, T _s means a control cycle (sampling cycle) in this control. n is a time step.

(Torque command calculation unit 121)
Torque command computation unit 121, the command rotational speed omega _ref ^* and the estimated rotational speed omega _r, determining the command torque T _e ^*. Specifically, the torque command calculation unit 121 obtains the command torque _Te ^{* according} to the equation (18). K _sP in equation (18) is a proportional gain. K _sI is an integral gain. The torque command calculation unit 121 is a known PI compensator.

(Amplitude command generator 122)
Amplitude command generator 122, the command torque T _e ^*, instruction amplitude | Ψ _s ^* | Request (target amplitude | | Ψ _s ^*). The amplitude command generator 122 can be configured using a lookup table, an operator storing a calculation formula (approximation formula), or the like. When using a look-up table, a look-up table representing the correspondence relationship between the command torque _Te ^* and the target amplitude | Ψ _s ^* | may be prepared in advance. Calculation formulas for operators can also be prepared in advance. Such a lookup table and calculation formula can be set based on measurement data or theory performed in advance. The specific method for specifying the target amplitude | Ψ _s ^* | is known literature (Yoji Takeda, Shigeo Morimoto, Nobuyuki Matsui, Yukio Honda, “Design and Control of an Embedded Magnet Synchronous Motor”, Ohm Corporation, 2001. Reference is made to October 25, etc.). In this embodiment, the relationship between the torque and the magnetic flux satisfying the maximum torque / current control (MTPA) that can generate the maximum torque with the minimum current is used.

(Amplitude command correction unit 123)
The amplitude command correcting unit 123 corrects the command amplitude | Ψ _s ^* | (target amplitude | Ψ _s ^* |) to the command amplitude | Ψ _s ^** |. The amplitude command correcting unit 123 is a delay filter. In the present embodiment, the amplitude command correction unit 123 is a primary low-pass filter that functions as an integrator. The amplitude command correcting unit 123 obtains the command amplitude | Ψ _s ^** | by using the equation (19). In Expression (19), g is a cutoff frequency.

(Torque deviation calculator 111)
Torque deviation calculation unit 111, the command torque T _e ^* and the estimated torque T _e and the deviation (torque deviation ΔT: T _e ^* -T _e) Request. A known operator may be used as the torque deviation calculation unit 111.

(Magnetic flux command calculation unit 112)
The magnetic flux command calculation unit 112 obtains a command magnetic flux vector ψ _s ^* (command amplitudes ψ _α ^* , ψ _β ^* ) from the command amplitude | Ψ _s ^** |, the torque deviation ΔT, and the phase θ _s . Specifically, the rotation amount Δθ _s of the motor magnetic flux is obtained from the equation (20). Using the equation (21), the phase θ _s ^* of the command magnetic flux vector Ψ _s ^* is obtained. Using the equations (22) and (23), the command amplitudes ψ _α ^* and ψ _β ^* are obtained. K _θP in equation (20) is a proportional gain. K _θI is an integral gain. The magnetic flux command calculation unit 112 brings the torque deviation ΔT close to zero. In this respect, it can be said that the magnetic flux command calculation unit 112 constitutes a torque compensation mechanism. When the magnetic flux command calculation unit 112 is incorporated in a digital control device such as a DSP or a microcomputer, the integrator required for the calculation in Expression (20) can be configured as a discrete system.

(Α-axis magnetic flux deviation calculator 113a, β-axis magnetic flux deviation calculator 113b)
The α-axis magnetic flux deviation calculating unit 113a obtains the command amplitude Ψ _α ^* and the estimated magnetic flux Ψ _α and obtains the deviation (magnetic flux deviation ΔΨ _α : Ψ _α ^* −Ψ _α ). The β-axis magnetic flux deviation calculation unit 113b obtains the command amplitude Ψ _β ^* and the estimated magnetic flux Ψ _β and obtains these deviations (magnetic flux deviation ΔΨ _β : Ψ _β ^* −Ψ _β ). As the magnetic flux deviation calculators 113a and 113b, known operators may be used.

(Voltage command calculation unit 107)
The voltage command calculation unit 107 obtains command shaft voltages v _α ^* and v _β ^* from the magnetic flux deviations ΔΨ _α and ΔΨ _β and the shaft currents i _α and i _β . Specifically, the voltage command calculation unit 107 obtains the α-axis command voltage v _α ^* using Expression (24). Moreover, the voltage command calculating part 107 calculates | requires (beta) axis command voltage v ( _beta) ^* using Formula (25).

(Α, β / u, v, w converter 114)
α, β / u, v, w conversion unit 114, the command-axis voltage v _alpha ^*, the v _beta ^*, the command voltage vector ^{_{v 2u *, v 2v *,}} v is converted to _2w ^*. Specifically, α, β / u, v , w conversion unit 114, by the equation (26), the command-axis voltage v α ^_*, v β ^* the command voltage vector ^{_{v 2u *, v 2v *,}} v to _2w ^* conversion to the command voltage vector ^{_{v 2u *, v 2v *,}} v and outputs the _2w ^*.

  Returning to FIG. 1, the remaining components of the motor control device 100 and the components connected to the motor control device 100 will be described below.

(First current sensor 105a, second current sensor 105b)
A known current sensor can be used as the first current sensor 105a and the second current sensor 105b. In the present embodiment, the first current sensor 105a is provided to measure the phase current i _u flowing through the u phase. The second current sensor 105b is provided to measure the phase current i _w flowing through the w phase. However, the first current sensor 105a and the second current sensor 105b may be provided so as to measure a two-phase current of a combination other than the u-phase and w-phase two phases.

(Switching unit 133)
Switching unit 133, the command voltage vector _{^{v 1u *, v 1v *,}} v 1w * and the command voltage vector _{^{v 2u *, v 2v *,}} v 2w * While selecting the command voltage vector v _u one selected ^* , V _v ^* , v _w ^* . That is, the switching unit 133 controls switching from the start synchronous operation to the position sensorless operation. The switching unit 133 is, for example, an analog switch or a multiplexer. FIG. 6 shows a configuration diagram of the switching unit 133.

(Duty generator 103)
Duty generation unit 103, the command voltage vector _{v u} ^*, v v ^*, the v _w ^*, the duty D _u, D _v, to produce a D _w. In the present embodiment, the duty generation unit 103 converts each component of the command voltage vectors v _u ^* , v _v ^* , and v _w ^* into the duty _Du , D _v , and D _w of each phase. Duty D _u, D _v, as the method of generating the D _w, the method may be used for use in general voltage-source PWM inverter. For example, the duties D _u , D _v , and D _w are obtained by dividing the command voltage vectors v _u ^* , v _v ^* , and v _w ^* by half the voltage value V _dc of the DC power supply 118 (FIG. 7). You may ask for it. In this case, the duty _Du is 2 ^* _vu ^* / _Vdc . The duty D _v is 2 × v _v ^* / V _dc . The duty D _w is 2 × v _w ^* / V _dc . Duty generation unit 103, duty D _u, D _v, and outputs the D _w.

(PWM inverter 104)
As shown in FIG. 7, the PWM inverter 104 includes a switching circuit 119a, 119b, 119c, 119d, 119e, 119f and a conversion circuit, a base driver 116, in which freewheeling diodes 120a, 120b, 120c, 120d, 120e, 120f are paired. A smoothing capacitor 117 and a DC power supply 118. The DC power supply 118 represents an output rectified by a diode bridge or the like. In the present specification, a configuration in which the conversion circuit and the smoothing capacitor 117 are combined is described as an inverter.

The PWM inverter 104 applies a voltage vector to the synchronous motor 102 by PWM control. Specifically, the power supply to the synchronous motor 102 is performed from the DC power source 118 via the switching elements 119a to 119f. More specifically, first, the duty D _u, D _v, D _w is input to the base driver 116. Then, the duty D _u, D _v, D _w is converted into a drive signal for electrically driving the switching elements 119A～119f. Next, each of the switching elements 119a to 119f operates according to the drive signal.

  In the present embodiment, the PWM inverter 104 is a three-phase switching circuit using switching elements 119a to 119f. Examples of the switching elements 119a to 119f include a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor).

(Synchronous motor 102)
The synchronous motor 102 is a control target of the motor control device 100. A voltage vector is applied to the synchronous motor 102 by the PWM inverter 104. “A voltage vector is applied to the synchronous motor 102” means that a voltage is applied to each of the three phases (U phase, V phase, W phase) on the three-phase AC coordinate in the synchronous motor 102. In the present embodiment, each of the three phases (U phase, V phase, W phase) is selected from two types: a high voltage phase having a relatively high voltage and a low voltage phase having a relatively low voltage. The synchronous motor 102 is controlled so as to be one of the following.

  The synchronous motor 102 is, for example, a permanent magnet synchronous motor. Examples of the permanent magnet synchronous motor include IPMSM (Interior Permanent Magnet Synchronous Motor) and SPMSM (Surface Permanent Magnet Synchronous Motor). The IPMSM has a saliency in which the d-axis inductance Ld and the q-axis inductance Lq are different (generally, a reverse saliency such that Lq> Ld), and a reluctance torque can be used in addition to the magnet torque. For this reason, the driving efficiency of the IPMSM is extremely high. As the synchronous motor 102, a synchronous reluctance motor can also be used.

(Starting method of synchronous motor 102 by motor control device 100 and its effect)
A method of starting the synchronous motor 102 by the motor control device 100 and its effect will be described with reference to FIG. In FIG. 8, the first period is a period including the starting point of the synchronous motor 102. The second period is a period following the first period. In the first period, the start synchronous operation is executed. In the second period, position sensorless operation is executed. In the following description, the time point when the start synchronous operation is switched to the position sensorless operation is referred to as operation mode switching. In FIG. 8, the switching of the operation mode corresponds to the time point when the operation period is switched from the first period to the second period.

In the first period, the start-up synchronous operation is executed while estimating the motor magnetic flux. However, in the start synchronous operation, the estimated phase of the motor magnetic flux is not referred to. In the start synchronous operation, the command rotational speed ω _ref ^* is gradually increased. Accordingly, the rotational speed of the synchronous motor 102 gradually increases and reaches a rotational speed at which position sensorless operation can be performed. The amplitude of the motor magnetic flux of the synchronous motor 102 also gradually increases and reaches the maximum amplitude ψ1. The maximum amplitude Ψ1 is the maximum amplitude of the motor magnetic flux during the period in which the start-up synchronous operation is performed.

  After the rotational speed of the synchronous motor 102 reaches the rotational speed at which the position sensorless operation can be performed, the start synchronous operation is switched to the position sensorless operation. That is, the second period starts. The second period may be started, for example, when the rotational speed of the synchronous motor 102 reaches the threshold rotational speed. The threshold rotation speed may be set to a rotation speed at which the magnetic flux calculation unit 108 can estimate the motor magnetic flux with high accuracy so as not to hinder the position sensorless operation. The threshold rotational speed may be, for example, about a fraction of the rated rotational speed to a few tenths.

The position sensorless operation is started using the motor magnetic flux estimated in the first period. Specifically, at the start time of the second period, the command amplitude | Ψ _s ^** | is set to the absolute value | Ψ _s | of the estimated magnetic flux Ψ _s at the end time of the first period (in this embodiment, the amplitude Ψ1). To do. That is, the amplitude command correcting unit 123 sets the initial value | Ψ _s ^** (t = 0) | of the command amplitude | Ψ _s ^** | as shown in Expression (27).

  The motor magnetic flux is estimated also in the position sensorless operation. In the position sensorless operation, the command amplitude that the motor amplitude should follow is determined so that the amplitude of the motor magnetic flux converges to the target amplitude. In the position sensorless operation, the estimated phase of the motor magnetic flux is referred to.

In the present embodiment, the amplitude command generator 122 continues to output the amplitude ψ2 as the target amplitude | ψ _s ^* |. The amplitude Ψ2 is relatively small because it is derived from the MTPA control. The amplitude ψ2 is continuously input to the amplitude command correcting unit 123. When the operation mode is switched, the initial value of the command amplitude | Ψ _s ^** | in the amplitude command correction unit 123 is set to the amplitude Ψ1. The amplitude Ψ1 is relatively large because it is derived from the start-up synchronous operation. That is, at the start time of the second period, a relatively small amplitude ψ2 is input to the amplitude command correcting unit 123, and a relatively large amplitude ψ1 is output from the amplitude command correcting unit 123 as a command amplitude | ψ _s ^** |. The After the start time of the second period, the output of the amplitude command correcting unit 123 approaches the input amplitude Ψ2. However, since the amplitude command correcting unit 123 is a low-pass filter (integrator), the command amplitude | Ψ _s ^** | gradually decreases from the amplitude Ψ1 to the amplitude Ψ2 (FIG. 8). As understood from FIG. 8, in this example, the amplitude of the motor magnetic flux changes in a time-differentiable manner during the period from when the operation mode is switched until the amplitude of the motor magnetic flux converges to the amplitude Ψ2.

The effect based on the amplitude command correction unit 123 will be described with reference to FIGS. 9A to 10B. 10A and 10B show simulation results when the motor control device 100 is used. 9A and 9B show simulation results when the amplitude command correcting unit 123 is removed from the motor control device 100 (conventional example). The first row from the top of FIGS. 9A to 10B represents the temporal change of the axial currents i _α and i _β . The second stage represents the time change of the shaft voltages v _α and v _β . The third stage represents the time change of the target amplitude | Ψ _s ^* | and the absolute value | Ψ _s | of the estimated magnetic flux Ψ _s . The fourth level represents the time change of the phase θ _s of the estimated magnetic flux ψ _s . In this simulation, the start synchronous operation is switched to the position sensorless operation around 0.48 s.

  9A and 9B, it can be seen that a surge voltage of 10 V or more is generated when the amplitude command correcting unit 123 is not used. On the other hand, it can be seen from FIGS. 10A and 10B that when the amplitude command correcting unit 123 is used, the voltage fluctuation is suppressed to about 2V. From the first stage of FIGS. 9A to 10B, when the amplitude command correction unit 123 is used, it is understood that the current fluctuation accompanying the switching of the operation mode from the start synchronous operation to the position sensorless operation is suppressed, and the torque It is understood that pulsation can be suppressed.

In the present embodiment, the command amplitude is set so that the difference between the motor magnetic flux amplitude and the command amplitude is smaller than the difference between the motor magnetic flux amplitude and the target amplitude when the operation mode is switched, and then the command amplitude is set to the target amplitude. Continuously approach the amplitude. Thereby, the surge voltage accompanying the switching of the operation mode by the switching unit is suppressed. Specifically, when the operation mode is switched, the command amplitude | Ψ _s ^** | is set to the absolute value | Ψ _s | of the estimated magnetic flux Ψ _s when the operation mode is switched. That is, at the time of switching the operation mode, the command amplitude | Ψ _s ^** | and the absolute value | Ψ _s | of the estimated magnetic flux Ψ _s are both Ψ1 = 3.8 Wb, and the difference between them is substantially zero. For this reason, unlike a conventional motor control device, a voltage surge due to a large difference (temporary amplitude deviation) between the command amplitude and the amplitude of the motor magnetic flux estimated by the start-up synchronous operation is unlikely to occur. Further, as can be seen from FIGS. 10A and 10B, since the amplitude command correcting unit 123 is a low-pass filter, it can take a long time for the motor magnetic flux to converge in the second period. This also suppresses the occurrence of voltage surges. The voltage surge is significantly suppressed when the amplitude command correcting unit 123 is used (FIGS. 10A and 10B) compared to when the amplitude command correcting unit 123 is omitted (FIGS. 9A and 9B). It is thought to be a thing. The command amplitude is set so that the difference between the motor magnetic flux amplitude and the command amplitude is smaller than the difference between the motor magnetic flux amplitude and the target amplitude when the operation mode is switched, and then the command amplitude is set to the target amplitude. May be close to each other.

Instead of the low-pass filter, another delay filter such as a filter based on a weight function may be used. The filter based on the weight function can also be configured such that the time change rate of the command amplitude | Ψ _s ^** | decreases linearly with time. Further, at the time of switching the operation mode, the command amplitude | Ψ _s ^** | does not have to be increased to the absolute value | Ψ _s | of the estimated magnetic flux Ψ _s at the time of switching the operation mode. In short, the amplitude command correcting unit 123 sets the command amplitude so that the difference between the motor magnetic flux amplitude and the command amplitude is smaller than the difference between the motor magnetic flux amplitude and the target amplitude when the operation mode is switched, and then It may be a delay filter that gradually brings the command amplitude closer to the target amplitude.

(Second Embodiment)
Hereinafter, a motor control device according to a second embodiment of the present invention will be described. Note that in the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  A motor control device 200 illustrated in FIG. 11 includes a synchronization control unit 231 and a position sensorless control unit 232 instead of the synchronization control unit 131 and the position sensorless control unit 132.

(Position sensorless control unit 232)
The position sensorless control unit 232 does not have the amplitude command correction unit 123 as shown in FIG. Therefore, the magnetic flux command computation unit 112, instruction amplitude | instead of instruction amplitude _{^{| | Ψ s ** Ψ s *}} | ( target amplitude | [psi _s ^* |) is used. The position sensorless control unit 232 operates so that the amplitude of the motor magnetic flux follows the target amplitude | Ψ _s ^* | immediately after the start of the position sensorless operation. When expressed as “the position sensorless control unit 232 performs position sensorless operation for setting the command amplitude so that the amplitude of the motor magnetic flux converges to the target amplitude”, the “command amplitude” is the same as the “target amplitude”. Both of these correspond to the command amplitude | Ψ _s ^* | (target amplitude | Ψ _s ^* |). The position sensorless control unit 232 obtains the command amplitude | Ψ _s ^* | even during the period in which the start-up synchronous operation is being performed.

(Synchronization control unit 231)
As shown in FIG. 13, the synchronization control unit 231 includes a synchronization current command unit 224 instead of the synchronization current command unit 124. The synchronous current command unit 224 outputs command axis currents i _d ^* and i _q ^* . The command axis currents i _d ^* and i _q ^* are generated by a method different from that in the first embodiment (see FIG. 14).

  A method of switching from the start synchronous operation to the position sensorless operation will be described with reference to FIG.

Step S101 is a step of setting the command axis currents i _d ^* and i _q ^* to initial values. In the present embodiment, in step S101, the d-axis command axis current i _d ^{* is set} to zero, and the q-axis command axis current i _q ^* is set to I _{q_douki} .

Step S102 is a step of acquiring the command rotational speed ω _ref ^* .

Step S103 is a step of determining whether or not the command rotational speed ω _ref ^* is greater than or equal to the threshold rotational speed. If it is determined in step S103 that the command rotational speed ω _ref ^* is greater than or equal to the threshold rotational speed, the process proceeds to step S104. If it is determined in step S103 that the command rotational speed ω _ref ^* is less than the threshold rotational speed, the process returns to step S102. In the initial stage of the start-up synchronous operation, the command rotational speed ω _ref ^* gradually increases from zero. Steps S102 and S103 are repeated until the command rotational speed ω _ref ^* reaches the threshold rotational speed. The threshold rotational speed is set to a rotational speed at which the magnetic flux calculation unit 108 can estimate the motor magnetic flux with high accuracy so as not to hinder the position sensorless operation. The threshold rotational speed may be, for example, about a fraction of the rated rotational speed to a few tenths.

Step S104 is a step of obtaining the command amplitude | Ψ _s ^* |.

Step S105 is a step of obtaining the absolute value | ψ _s | of the estimated magnetic flux ψ _s .

Step S106 is a step of determining whether or not the difference between the command amplitude | Ψ _s ^* | and the absolute value | Ψ _s | (amplitude deviation | Ψ _s | − | Ψ _s ^* |) is smaller than an allowable value. . In step S106, when it is determined that the amplitude deviation | Ψ _s | − | Ψ _s ^* | is smaller than the allowable value, the start-up synchronous operation is switched to the position sensorless operation. If it is determined in step S106 that the amplitude deviation | Ψ _s | − | Ψ _s ^* | is equal to or greater than the allowable value, the command axis current i _q ^* is decreased (step S107), and the process returns to step S104. Until the amplitude deviation | Ψ _s | − | Ψ _s ^* | becomes less than the allowable value, Steps S104 to S107 are repeated, and the command axis current i _q ^* and the absolute value | Ψ _s | gradually decrease.

In the start-up synchronous operation of the present embodiment, not only the estimated magnetic flux Ψ _s but also the calculation of the command amplitude | Ψ _s ^* | is necessary. In this embodiment, the estimated magnetic flux Ψ _s is obtained as described with reference to FIG. The torque control section 109, the estimated flux [psi _s and axis current i _alpha, and a i _beta, estimated torque T _e is determined. The amplitude command generating unit 122, instruction amplitude from the command torque T _e ^* rather than estimated torque T _e | Ψ _s ^* | is generated.

  Note that the operation based on steps S101 to S107 shown in FIG. 14 may be assigned to any element shown in the figure, or may be assigned to another element not shown. These operations can be performed by the switching unit 133, for example.

(Starting method of synchronous motor 102 by motor control device 200 and its effect)
A method of starting the synchronous motor 102 by the motor control device 200 and its effect will be described with reference to FIG. In FIG. 15, the first period is a period including the starting point of the synchronous motor 102. The second period is a period following the first period. In the first period, the start synchronous operation is executed. In the second period, position sensorless operation is executed.

In the first period, the start-up synchronous operation is executed while estimating the motor magnetic flux. However, in the first period, the estimated phase of the motor magnetic flux is not referred to. In the start synchronous operation, the command rotational speed ω _ref ^* and the rotational speed of the synchronous motor 102 are gradually increased to reach the threshold rotational speed. The amplitude of the motor magnetic flux of the synchronous motor 102 (the absolute value | Ψ _s | of the estimated magnetic flux Ψ _s ) gradually increases and reaches the maximum amplitude Ψ 1.

If the amplitude deviation | Ψ _s | − | Ψ _s ^* | is equal to or greater than the allowable value when the command rotational speed ω _ref ^* reaches the threshold rotational speed, the amplitude deviation | Ψ _s | − | Ψ _s ^* | The q-axis command axis current i _q ^* gradually decreases until it becomes less than the value.

When the amplitude deviation | Ψ _s | − | Ψ _s ^* | becomes less than the allowable value, the position sensorless operation is started. That is, the second period starts. The amplitude command generator 122 performs MTPA control. For this reason, the amplitude command generator 122 outputs a relatively small amplitude ψ 2 as the command amplitude | ψ _s ^* | (target amplitude | ψ _s ^* |). In the present embodiment, the amplitude Ψ 2 is input to the magnetic flux command calculation unit 112 as it is. For this reason, the amplitude of the motor magnetic flux decreases to the amplitude ψ2 immediately after the start of the second period.

In the example shown in FIG. 15, the motor flux, over time t _p decreases gradually from the amplitude Ψ1 to amplitude? 3. t _p is about several tens of ms to several hundreds of ms. As can be understood from FIG. 15, in this example, the motor magnetic flux changes in a time-differentiable manner during the period until the motor magnetic flux decreases from the amplitude ψ1 to the amplitude ψ3.

  If the amplitude of the motor magnetic flux increased to the amplitude ψ1 is maintained until the switching of the operation mode, the amplitude of the motor magnetic flux is greatly reduced immediately after the start of the second period. On the other hand, in the present embodiment, the amplitude of the motor magnetic flux increased to the amplitude ψ1 is decreased to the amplitude ψ3 in the first period. Therefore, the decrease width of the amplitude of the motor magnetic flux immediately after the start of the second period is reduced.

The effect based on this embodiment is demonstrated using FIG. 16A and 16B. 16A and 16B show simulation results when the motor control device 200 is used. The first row from the top of FIGS. 16A and 16B represents the temporal change of the axial currents i _α and i _β . The second stage represents the time change of the shaft voltages v _α and v _β . The third stage represents the time change of the command amplitude | Ψ _s ^* | (target amplitude | Ψ _s ^* |) and the absolute value | Ψ _s | of the estimated magnetic flux Ψ _s . The fourth level represents the time change of the phase θ _s of the estimated magnetic flux ψ _s . In this simulation, the q-axis command axis current i _q ^* starts decreasing in the vicinity of 0.3 s, and the start-up synchronous operation is switched to the position sensorless operation in the vicinity of 0.56 s.

  From FIG. 16A and FIG. 16B, it turns out that voltage fluctuation is suppressed to about 2V in this embodiment. From FIG. 16A and FIG. 16B, it is understood that the current fluctuation accompanying the switching from the start synchronous operation to the position sensorless operation is suppressed, and it is understood that the torque pulsation is suppressed.

  In this embodiment, the synchronous current is continuously reduced before the operation mode is switched. Thereby, the amplitude of the motor magnetic flux is reduced to the amplitude Ψ2. In the present embodiment, the amount of decrease in the amplitude of the motor magnetic flux when the operation mode is switched is thus reduced. For this reason, the voltage surge accompanying the large difference (temporary amplitude deviation) between the command amplitude and the motor magnetic flux estimated by the start synchronous operation is suppressed. This is the reason why the voltage surge is greatly suppressed in the case of using the motor control device 200 (FIGS. 16A and 16B) compared to the case of using the conventional motor control device (FIGS. 9A and 9B). It is believed that there is. Note that the synchronous current may be decreased stepwise before switching the operation mode.

  The technique described in the first embodiment can be combined with the technique described in the second embodiment. That is, (i) the synchronous current is decreased continuously or stepwise before switching of the operation mode by the switching unit, and (ii) the motor magnetic flux amplitude and the target amplitude at the time of switching of the operation mode by the switching unit. A configuration may be employed in which the command amplitude is set so that the difference between the motor magnetic flux amplitude and the command amplitude is smaller than the difference, and then the command amplitude is made to approach the target amplitude continuously or stepwise.

  In addition, a motor control device having a configuration other than the configurations described in the first embodiment and the second embodiment can be used. In short, the motor control device according to the present disclosure adjusts at least one of the synchronous current before switching of the operation mode by the switching unit and the command amplitude after switching of the operation mode by the switching unit. Before or after the switching of the operation mode by, the difference between the motor magnetic flux amplitude and the target amplitude is decreased continuously or stepwise.

  The present invention can be applied to synchronous motors such as SPMSM and IPMSM. Those synchronous motors are suitable for a heat pump refrigeration apparatus used in an air conditioner or a water heater.

100, 200 Motor controller 102 Synchronous motor 104 PWM inverter 105a First current sensor 105b Second current sensor 106 u, w / α, β converter 107 Voltage command calculator 108 Magnetic flux calculator 109 Torque calculator 110 Speed / position calculation Unit 111 torque deviation calculation unit 112 magnetic flux command calculation unit 113a α-axis magnetic flux deviation calculation unit 113b β-axis magnetic flux deviation calculation unit 114 α, β / u, v, w conversion unit 116 base driver 117 smoothing capacitor 118 DC power supply 119a to 119f switching Elements 120a to 120f Freewheeling diode 121 Torque command calculation unit 122 Amplitude command generation unit 123 Amplitude command correction unit 124, 224 Synchronous current command unit 125 Voltage command calculation unit 126 d, q / u, v, w conversion unit 127 u, w / d, q converter 128 integrator 131, 231 synchronous control Parts 132 and 232 position sensorless control unit 133 switching unit 150 u, v, w / d, q conversion unit

Claims (7)

A magnetic flux estimator for estimating a motor magnetic flux that is a magnetic flux of the synchronous motor;
Regardless of the phase of the motor magnetic flux, while referring to the phase of the motor magnetic flux estimated by the magnetic flux estimator from the start synchronous operation for supplying the synchronous current necessary for starting the synchronous motor to the synchronous motor A position sensorless operation that is executed, and a switching unit that controls switching to a position sensorless operation that sets a command amplitude that the amplitude of the motor magnetic flux should follow so that the amplitude of the motor magnetic flux converges to a target amplitude; ,
With
(I) The synchronous current is decreased continuously or stepwise before switching the operation mode by the switching unit, and / or (ii) the amplitude of the motor magnetic flux at the time of switching the operation mode by the switching unit The command amplitude is set so that the difference between the amplitude of the motor magnetic flux and the command amplitude is smaller than the difference from the target amplitude, and then the command amplitude is made to approach the target amplitude continuously or stepwise. , Motor control device.   The motor control device sets the command amplitude so that a difference between the motor magnetic flux amplitude and the command amplitude is smaller than a difference between the motor magnetic flux amplitude and the target amplitude when the operation mode is switched. Thereafter, the motor control device according to claim 1, further comprising a delay filter that gradually brings the command amplitude closer to the target amplitude.   The motor control device according to claim 2, wherein the delay filter is a low-pass filter or a filter based on a weight function.   The motor control device according to claim 1, wherein the motor control device decreases the synchronous current continuously or stepwise before switching the operation mode. The motor control device includes a synchronous control unit that executes the startup synchronous operation, and a position sensorless control unit that executes the position sensorless operation,
The synchronization control unit
A first three-phase two-phase coordinate converter for converting a phase current on the three-phase AC coordinate in the synchronous motor into a first axis current on the first two-phase coordinate;
A first voltage command calculation unit that generates a first axis voltage on the first two-phase coordinates corresponding to a voltage vector to be applied to the synchronous motor from the first axis current;
The position sensorless controller is
A second three-phase two-phase coordinate converter for converting the phase current into a second axial current on a second two-phase coordinate;
The magnetic flux estimator for estimating the motor magnetic flux from the second axial current and the second axial voltage on the second two-phase coordinates corresponding to the voltage vector;
A torque calculator for estimating the motor torque from the second shaft current and the estimated motor magnetic flux;
A command magnetic flux vector that the motor magnetic flux should follow from the estimated torque deviation between the motor torque and the command torque that the motor torque should follow, the estimated phase of the motor magnetic flux, and the command amplitude. A magnetic flux command calculation unit for identifying
A second voltage command calculation unit that specifies the second shaft voltage from a magnetic flux deviation between the command magnetic flux vector and the estimated motor magnetic flux,
The motor control device uses the magnetic flux estimator in the position sensorless controller based on the second axis current and the first axis voltage during the start-up synchronous operation. The motor control device according to claim 1, wherein the motor control device is configured to estimate a motor magnetic flux. Estimating a motor magnetic flux that is a magnetic flux of the synchronous motor;
Position sensorless, which is executed while referring to the estimated phase of the motor magnetic flux from the start synchronous operation that supplies the synchronous motor with the synchronous current necessary for starting the synchronous motor regardless of the phase of the motor magnetic flux. A step of switching the operation mode to a position sensorless operation for setting a command amplitude that the amplitude of the motor magnetic flux should follow so that the amplitude of the motor magnetic flux converges to a target amplitude;
Including
(I) reducing the synchronous current continuously or stepwise before switching the operation mode; and / or (ii) difference between the amplitude of the motor magnetic flux and the target amplitude at the time of switching the operation mode. A motor control method in which the command amplitude is set so that a difference between the amplitude of the motor magnetic flux and the command amplitude becomes smaller, and then the command amplitude is made to approach the target amplitude continuously or stepwise. A magnetic flux estimator for estimating a motor magnetic flux that is a magnetic flux of the synchronous motor;
Regardless of the phase of the motor magnetic flux, while referring to the phase of the motor magnetic flux estimated by the magnetic flux estimator from the start synchronous operation for supplying the synchronous current necessary for starting the synchronous motor to the synchronous motor A position sensorless operation that is executed, and a switching unit that controls switching to a position sensorless operation that sets a command amplitude that the amplitude of the motor magnetic flux should follow so that the amplitude of the motor magnetic flux converges to a target amplitude; ,
With
By adjusting at least one of the synchronous current before switching of the operation mode by the switching unit and the command amplitude after switching of the operation mode by the switching unit, switching of the operation mode by the switching unit is performed. A motor control device that reduces the difference between the amplitude of the motor magnetic flux and the target amplitude continuously or stepwise before or after.

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