Motor control device and motor control method

Abstract

This makes it easier to control the motor's d-axis current without having to perform any specific actions on the motor. [Solution] The motor control device includes: an induction current estimation unit that estimates the induced current generated by the operation of the motor based on a speed command value notified from an external source or the actual speed detected by a speed detection unit that detects the rotational speed of the motor; a suppressable current estimation unit that estimates a suppressable current that flows in a direction that suppresses the d-axis component of the induced current based on the q-axis component of the induced current and the q-axis current command value; a suppressable current calculation unit that calculates a suppressable current whose absolute value is smaller than the suppressable current based on predetermined parameters; and a d-axis current command value calculation unit that calculates a d-axis current command value based on the d-axis component of the induced current and the suppressable current.

Description

[Technical Field]

[0001] This disclosure relates to a motor control device and a motor control method. [Background technology]

[0002] Patent Document 1 discloses a calculation device that easily and accurately adjusts parameters used for field weakening control in an electric motor. This calculation device includes means for acquiring a set of values ​​including the rotational speed when the rotational speed is increased while maintaining the torque of the electric motor at a predetermined value, the value of the q-axis current and the value of the d-axis current in the excitation circuit of the electric motor, a command value for the q-axis voltage to generate the q-axis current in the excitation circuit, and a command value for the d-axis voltage to generate the d-axis current in the excitation circuit; means for acquiring circuit parameters of the excitation circuit by applying a model equation determined by a set of values ​​in the range of rotational speeds in which the value of the q-axis current is constant to a theoretical equation that satisfies the rotational speed of the electric motor, the q-axis current, the d-axis current, the q-axis voltage, the d-axis voltage, and the circuit parameters of the excitation circuit; and means for determining parameters for adjusting the current value of the d-axis current when rotating the electric motor based on the acquired circuit parameters. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-119473 [Overview of the project] [Problems that the invention aims to solve]

[0004] This disclosure was devised in view of the conventional circumstances described above, and aims to provide a motor control device and a motor control method that can more easily control the d-axis current of a motor without requiring the motor to perform any specific operations. [Means for solving the problem]

[0005] This disclosure provides a motor control device comprising: an induction current estimation unit that estimates an induced current generated by the operation of the motor based on a speed command value notified from an external source or an actual speed detected by a speed detection unit that detects the rotational speed of the motor; a suppressable current estimation unit that estimates a suppressable current that flows in a direction that suppresses the d-axis component of the induced current based on the q-axis component of the induced current and a q-axis current command value; a suppressable current calculation unit that calculates a suppressable current whose absolute value is smaller than the suppressable current based on predetermined parameters; and a d-axis current command value calculation unit that calculates a d-axis current command value based on the d-axis component of the induced current and the suppressable current.

[0006] Furthermore, this disclosure provides a motor control method that estimates the induced current generated by the operation of the motor based on a speed command value notified from an external source or the actual speed detected by a speed detection unit that detects the rotational speed of the motor; estimates a suppressable current that flows in a direction that suppresses the d-axis component of the induced current based on the q-axis component of the induced current and a q-axis current command value; calculates a suppression current whose absolute value is smaller than the suppressable current based on predetermined parameters; and calculates a d-axis current command value based on the d-axis component of the induced current and the suppression current. [Effects of the Invention]

[0007] According to this disclosure, it is possible to more easily control the d-axis current of a motor without having to perform any specific operations on the motor. [Brief explanation of the drawing]

[0008] [Figure 1] Block diagram showing an example configuration of the motor device according to this embodiment. [Figure 2] This figure shows an example of the relationship between the rotor, torque current, and reactive current of the motor according to this embodiment. [Figure 3] Block diagram showing an example configuration of the current command calculation unit according to this embodiment. [Figure 4] This figure shows an example of the relationship between the required torque current and the induced current according to this embodiment. [Figure 5]Diagram illustrating the suppression current according to this embodiment. [Figure 6] A diagram illustrating the suppressable current and suppressed current according to this embodiment: (a) a diagram including the q-axis component, (b) a diagram including only the d-axis component, and (c) a diagram showing the suppressable current and suppressed current. [Figure 7] A flowchart showing an example of a motor control method according to this embodiment. [Modes for carrying out the invention]

[0009] (Background leading to this disclosure) It is known that the current flowing through the windings of a motor consists of a q-axis current, which generates rotational torque in the motor, and a d-axis current, also known as reactive current. This d-axis current generates a magnetic field parallel to the magnet, resulting in zero rotational torque and thus wasted current, which should be reduced as much as possible. On the other hand, when the motor is operating at high speed, the d-axis current generated by the back electromotive force cannot be completely suppressed by the applied voltage, and a certain degree of it must be tolerated. Calculating how much this tolerable d-axis current can be reduced is difficult because many parameters are involved, making it challenging to set them. These parameters are not limited to the q-axis current command value, the voltage supplied to the motor, and the motor's operating (i.e., rotation) speed, but also include winding characteristics and rotor characteristics, among others. In particular, winding characteristics and rotor characteristics, such as resistance, inductance, electromotive force constant, temperature characteristics, and hysteresis, cannot be directly measured. Furthermore, the induced current that flows with the rotation of the motor cannot be directly measured and can only be estimated from the aforementioned parameters.

[0010] For example, according to the arithmetic unit of Patent Document 1, in calculating the d-axis current of a motor, it is necessary to adjust parameters regarding winding characteristics and rotational characteristics based on the behavior when the motor executes a specific operation (for example, load or speed). However, when the motor is incorporated into a robot (for example, an industrial robot) used in a factory or the like, it is difficult to cause the motor to perform the above-described specific operation for calculating the d-axis current, and from the viewpoint of safety when using the robot, such parameter adjustment is difficult. Thus, although it is conceivable to adjust each parameter individually while measuring the actual behavior of the motor, in practice, it is difficult to adjust because there are many parameters.

[0011] Therefore, an object of the present disclosure is to provide a motor control device and a motor control method that can more easily control the d-axis current of a motor without causing the motor to perform a specific operation or the like.

[0012] Hereinafter, embodiments specifically disclosing the motor control device and the motor control method according to the present disclosure will be described in detail with reference to the drawings as appropriate. However, a more detailed description may be omitted as necessary. For example, detailed descriptions of already well-known matters or duplicate descriptions for substantially the same configuration may be omitted. This is to avoid making the following description unnecessarily redundant and to facilitate understanding by those skilled in the art. The attached drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and it is not intended to limit the subject matter described in the claims thereby.

[0013] (Embodiment 1) 1. Regarding the motor device First, referring to FIGS. 1 and 2, an example of the motor device 100 according to the present embodiment will be described. FIG. 1 is a block diagram showing an example of the configuration of the motor device 100 according to the present embodiment. FIG. 2 is a diagram showing an example of the relationship between the rotor, torque current, and reactive current of the motor 18 according to the present embodiment. The motor device 100 includes at least a position controller 10, a speed controller 11, a current controller 101, an inverter 17, a motor 18, a position detector 21, and a storage unit 102.

[0014] The position controller 10 calculates the deviation between the position command of the rotor input from a higher-level device (not shown) such as a Programmable Logic Controller (PLC) and the position (detection position) of the rotor of the motor 18 detected by the position detector 21. The position controller 10 calculates a speed command including a speed command value by multiplying the calculated deviation by a position deviation gain.

[0015] The speed controller 11 multiplies the integral component of the deviation between the speed command calculated by the position controller 10 and the detected speed detected by the speed detector 22 by a speed integral gain, and multiplies the sum of the calculation result and the speed deviation by a speed proportional gain to calculate a torque command and input it to the current controller 101. The speed controller 11 also inputs the speed command calculated by the position controller 10 to the current controller 101.

[0016] The inverter 17 generates an AC voltage for each phase of a three-phase AC based on a voltage command from the current controller 101 (specifically, an on-off signal from a PWM calculation unit 16 described later), applies it to the motor 18, and drives the motor 18. The inverter 17 is also called a power amplifier. Information (signal) regarding the supply voltage to the inverter 17 is input to the current command calculation unit 12 of the current controller 101.

[0017] Motor 18 is called an AC synchronous motor, and among Permanent Magnet (PM) motors that have permanent magnets on the rotor, it is a Surface Permanent Magnet Synchronous Motor (SPMSM), which is a motor with low saliency in which the permanent magnets are attached to the surface of the rotor.

[0018] The position detector 21 is a sensor that informs the current controller 101 of the rotation angle of the motor 18. The position detector 21 is also called a rotary encoder.

[0019] The current controller 101 is configured using, for example, a Central Processing Unit (CPU) or a Field Programmable Gate Array (FPGA), and works in cooperation with the memory unit 102 to perform various processes and controls. Specifically, the current controller 101 refers to the programs and data held in the memory unit 102 and executes those programs to realize control of the q-axis current and d-axis current supplied to the rotor of the motor 18.

[0020] The memory unit 102 includes, for example, Random Access Memory (RAM) used as work memory when executing each process of the current controller 101, and Read Only Memory (ROM) which stores programs and data that define the operation of the current controller 101. The RAM temporarily stores data or information generated or acquired by the current controller 101. The ROM contains a program that defines the operation of the current controller 101. This program may be a motor control program.

[0021] Here, the details of the configuration of the current controller 101 will be explained. The current controller 101 generates a current command value so that the motor 18 can exert the commanded torque with the smallest possible current, based on the torque command calculated by the speed controller 11, the voltage supplied to the inverter 17 (supply voltage), and the detected speed detected by the speed detector 22. The current controller 101 generates a voltage command corresponding to the deviation between the generated current command value and the magnitude of the current actually flowing through the rotor of the motor 18 detected by the current detector 19 (detected current), and inputs it to the inverter 17. Typically, a PI controller is used as the current controller 101.

[0022] The current controller 101 comprises at least a current command calculation unit 12, a d-axis current controller 13, a q-axis current controller 14, a voltage coordinate transformation unit 15, a PWM calculation unit 16, a current detector 19, a current coordinate transformation unit 20, and a speed detector 22.

[0023] The current command calculation unit 12 receives the torque command calculated by the speed controller 11 and uses the speed command from the speed controller 11 or the actual rotor speed information of the motor 18 detected by the speed detector 22 to calculate and generate a d-axis current command including the command value of the d-axis current after field weakening (Id_ref) and a q-axis current command including the command value of the q-axis current corresponding to the rotational torque based on the torque command. A detailed configuration example of this current command calculation unit 12 will be described later with reference to Figure 3.

[0024] The command value (Id_ref) of the d-axis current generated by the current command calculation unit 12 is input to a differencer (e.g., an adder) that calculates the difference between the command value (Id_ref) of the d-axis current and the current value (Id) of the d-axis current. This differencer calculates the difference between the command value (Id_ref) of the d-axis current and the current value (Id) of the d-axis current from the current coordinate transformation unit 20. This calculated difference value is input to the d-axis current controller 13.

[0025] The d-axis current controller 13 calculates a d-axis voltage value (Vd) to supply a d-axis current that reduces or eliminates the difference value (see above) input from the differencer, so that the error between the command value (Id_ref) of the d-axis current indicated by the d-axis current command from the current command calculation unit 12 and the actual current d-axis current value (Id) becomes zero. The d-axis current controller 13 generates a d-axis voltage command, which is a command for the calculated d-axis voltage value (Vd), and inputs it to the voltage coordinate transformation unit 15.

[0026] The q-axis current controller 14 calculates a q-axis voltage value (Vq) to supply a q-axis current that reduces or eliminates the difference value (see above) input from the differencer, so that the error between the command value (Iq_ref) of the q-axis current indicated by the q-axis current command from the current command calculation unit 12 and the actual current q-axis current value (Iq) becomes zero. The q-axis current controller 14 generates a q-axis voltage command, which is a command for the calculated q-axis voltage value (Vq), and inputs it to the voltage coordinate transformation unit 15.

[0027] The q-axis current, as shown in Figure 2, is the torque current, which generates rotational torque by creating a magnetic field perpendicular to the rotor (e.g., the magnet) of the motor 18. On the other hand, the d-axis current is what is known as reactive current, which is generated by the rotation of the rotor of the motor 18. In other words, the d-axis current generates a magnetic field parallel to the rotor (e.g., the magnet) of the motor 18, resulting in zero rotational torque. That is, the d-axis current is a wasted current for the rotation of the rotor of the motor 18, and if reactive currents like the d-axis current become large, it can cause burnout of the motor 18 windings, so it should be suppressed as much as possible.

[0028] The voltage coordinate transformation unit 15 uses the d-axis voltage value (Vd) from the d-axis current controller 13 and the q-axis voltage value (Vq) from the q-axis current controller 14 to calculate the command values ​​(Vu, Vv, Vw) for the voltage of each phase of the three-phase AC, and inputs them to the PWM calculation unit 16.

[0029] The PWM calculation unit 16 calculates the duty cycle in pulse width modulation (PWM) based on the ratio of the command values ​​(Vu, Vv, Vw) of the voltage of each phase from the voltage coordinate conversion unit 15 to the maximum DC voltage, and inputs an on / off signal based on the calculated duty cycle to the inverter 17.

[0030] The current detector 19 detects the current values ​​(Iu, Iv, Iw), which are the magnitudes of the current actually flowing through each phase of the rotor of the motor 18.

[0031] The current coordinate transformation unit 20 performs a three-phase to two-phase conversion based on the current values ​​(Iu, Iv, Iw) from the current detector 19, and detects the d-axis current value (Id), which is the actual value of the current d-axis current flowing through the rotor of the motor 18, and the q-axis current value (Iq), which is the actual value of the current q-axis current.

[0032] The speed detector 22 calculates the detected speed, which is the rotational speed of the rotor of the motor 18, by differentiating the detected position from the position detector 21 with respect to time.

[0033] 2. Current command calculation unit Next, the detailed configuration of the current command calculation unit 12 will be described with reference to Figures 3 to 6. Figure 3 is a block diagram showing an example of the configuration of the current command calculation unit according to this embodiment. Figure 4 is a diagram showing an example of the relationship between the required torque current and the induced current according to this embodiment. Figure 5 is a diagram illustrating the suppression current according to this embodiment. Figure 6 is a diagram illustrating the suppressable current and the suppression current according to this embodiment, and includes (a) a diagram including the q-axis component, (b) a diagram including only the d-axis component, and (c) a diagram showing the suppressable current and the suppression current. As shown in Figure 3, the current command calculation unit 12 comprises a q-axis current command calculation unit 121, an induced current estimation unit 122, a suppressable current estimation unit 123, a suppression current calculation unit 124, and a d-axis current command value calculation unit 125.

[0034] The q-axis current command calculation unit 121 receives the torque command calculated by the speed controller 11 and calculates and generates a q-axis current command that includes a command value (Iq_ref) for the q-axis current corresponding to the rotational torque based on the torque command. This q-axis current command is input to the differencer (see above) and also to the suppressable current estimation unit 123.

[0035] The induced current estimation unit 122 estimates the q-axis and d-axis components of the induced current (see Figure 4) generated by the change in the magnetic field within the motor winding due to the rotational movement of the magnets on the rotor of the motor 18, based on the speed command value input to the speed controller 11 or the actual rotor speed detection value of the motor 18 detected by the speed detector 22. The induced current is expressed as a vector having a q-axis component and a d-axis component, and the q-axis component of the induced current is i q induced Let the d-axis component of the induced current be i d induced (See equation (1)). The induced current increases as the rotational speed of the motor 18's rotor increases.

[0036] The induced current is calculated as shown in equation (1) below. The matrix portion on the right side of equation (1) represents admittance, and the column vector on the right side of equation (1) represents the induced voltage. In equation (1), r is the phase resistance, and L d,q ω is the inductance of the d-axis and q-axis, and ω is the rotational speed (detection speed) of the rotor of motor 18, and d / dt(i a ) is the time derivative of the a-axis current, where a is d and q respectively. The q-axis component of the induced current is input to the suppressable current estimation unit 123, and the d-axis component of the induced current is input to the d-axis current command value calculation unit 125.

[0037]

number

[0038] The suppressable current estimation unit 123 estimates a suppressable current that will cause the d-axis component of the induced current (see Figure 6(b)) to flow in a direction that suppresses or reduces it, based on the detected or fixed value of the supply voltage to the inverter 17, using the q-axis component of the induced current from the induced current estimation unit 122 and the command value of the q-axis current indicated by the q-axis current command from the q-axis current command calculation unit 121.

[0039] Now, referring to Figure 4, we will explain the voltage application required to deliver the necessary torque current.

[0040] As shown in Figure 4, the aforementioned induced current is generated as the rotor of the motor 18 rotates, relative to the command value (Iq_ref) of the q-axis current generated by the q-axis current command calculation unit 121. Therefore, as shown in Figure 4, it is necessary to apply a voltage in such a way as to achieve the command value of the q-axis current while suppressing or reducing the d-axis component of the induced current.

[0041] However, as shown in Figure 5, there are actually conditions for the supply voltage that can be supplied to the motor device 100. In other words, the supply voltage that can be supplied limits the voltage that the inverter 17 can apply to the motor 18, and the range of current that can flow is limited to within the circle CIR1 in Figure 5. The suppressable current corresponds to the d-axis component from the center O1 of circle CIR1 shown in Figure 5 to the intersection with the line of the q-axis current command. Note that the radius length of this circle CIR1 has the characteristic that it becomes shorter when the supply voltage is low and when the rotational speed of the rotor of the motor 18 increases. Also, the center O1 of circle CIR1 is the position indicated by the induced current vector. This means that when the inverter does not apply voltage, only induced current flows. As shown in Figure 5, if the radius length of circle CIR1 is insufficient, the range of current that can flow (in other words, the magnitude) will be limited to a portion of the d-axis component of the induced current so that the current can achieve the command value of the q-axis current. That is, if the supply voltage is not sufficiently high, it becomes necessary to allow reactive current (d-axis current) as necessary reactive current. As a result, it is found that in order to drive the motor 18 with both high speed and high torque, it is necessary to control the reactive current (d-axis current) in the current command calculation unit 12.

[0042] Therefore, as shown in Figures 6(a) to (c), it is necessary to estimate the suppressable current.

[0043] The suppressable current is the current component that suppresses or reduces the absolute value of the d-axis current, which is the reactive current. In other words, Figure 6(a) is the same as Figure 5, and shows the case where the suppressable current can be estimated as the ideal suppression current. That is, the suppressable current can be used as the suppression current itself.

[0044] Figure 6(b) extracts only the d-axis component from Figure 6(a). In this case, if the estimation of the suppressable current in Figure 6(a) is strictly correct, it will remain within the circle CIR1, which represents the range of current that can be supplied by the inverter 17's supply voltage. However, since there will inevitably be variations in the estimation, it is better to allow for some margin. Therefore, the suppression current calculation unit 124 calculates a suppression current, as shown in Figure 6(c), whose absolute value is smaller than the suppressable current calculated as shown in Figure 6(b), based on an adjustment parameter whose value ranges from 0 to 1.

[0045] The adjustment parameter should be set based on at least one of the following: the rotor speed command value of motor 18, the speed detection value which is the actual speed of the rotor of motor 18, and the q-axis current command value of motor 18. The adjustment parameter, which is a multiplier (in other words, a coefficient) used when calculating the suppressed current from the suppressable current, can be a multiplier greater than 0 (no suppression) and less than 1 (total suppression). A smaller multiplier emphasizes the stability of motor 18's rotation, while a larger multiplier emphasizes preventing winding burnout. Specifically, the d-axis current command is obtained by multiplying the minimum d-axis current command, calculated from the required torque, supply voltage, operating speed, and roughly adjusted motor characteristic values, by an adjustment multiplier of 0.0 to 1.0, excluding the d-axis current that flows when the control voltage is 0V.

[0046] Specifically, the suppressable current estimation unit 123 calculates the suppressable current as shown in equation (2) below. The calculated suppressable current value is input to the suppressable current calculation unit 124. Vis the voltage condition radius and corresponds to the radius length of the circle CIR1 shown in FIG. 5 or FIGS. 6(a) to (c).

[0047] [Number]

[0048] The suppression current calculation unit 124 multiplies the suppression current i, which is the result calculated by the suppressible current estimation unit 123, suppressible by, for example, the adjustment parameter r suppressible (specifically, a value in the range from 0 to 1) to calculate the suppression current i suppressing along Equation (3). The calculated value of the suppression current is input to the d-axis current command value calculation unit 125.

[0049] [Number]

[0050] The d-axis current command value calculation unit 125 adds the suppression current i, which is the result calculated by the suppression current calculation unit 124, suppressing and the d-axis component of the induced current from the induced current estimation unit 122 to generate a d-axis current command including the command value of the d-axis current along Equation (4). The command value of the d-axis current is the sum of the suppression current i suppressible multiplied by an adjustment parameter (greater than 0 and less than 1) and the d-axis component of the induced current.

[0051] [Number]

[0052] Note that the current controller 101 may further include a voltage detection unit that detects the voltage supplied to the inverter 17 that controls the AC voltage applied to the motor 18 and inputs the detected voltage value to the suppressible current estimation unit 123. In this case, the suppressible current estimation unit 123 may calculate the suppressible current based on the q-axis component of the induced current, the q-axis current command value, and the detected voltage value.

[0053] Each of the above equations (1) to (4) is merely an example of a calculation formula. In other words, in a normal SPMSM, the inductance is the same for the d axis and the q axis, so in equation (1), the inductance L of the d axis is used. d and the inductance L of the q axis q This is identical to the previous formula. However, in various situations, such as when different inductances are used, when the time derivative component of the current is ignored (which may result in high computational costs), or when there are different variations in the conversion of three-phase (UVW) current to two-phase (dq) current (absolute conversion / relative conversion), the following formula may become a different formula.

[0054] Here, we assume that the current commands id, iq, and their derivatives are independent. Furthermore, obtaining accurate derivatives is usually difficult in numerical calculations, and it is common to obtain them simply using the following method, which is acceptable. Let Id = Iq = 0 (because ψω is dominant in the high-velocity range). The derivative of the past values ​​of Id and Iq is obtained by applying a first-order high-pass filter. The derivative is the backward difference between the past values ​​of Id and Iq. The differential value is calculated by taking the back difference of the low-pass filter applied to the past values ​​of Id and Iq (for noise reduction).

[0055] Furthermore, the adjustment parameters do not need to be limited to fixed values ​​and may change according to the rotational speed of the motor 18 rotor or the commanded value of the q-axis current. For example, it is understandable and possible to substitute for the inability to operate at high speed / high torque, but it is not understandable or possible to substitute for the inability to operate at low speed / low torque. Substitution here means that it is possible to take measures such as reducing the speed, reducing the acceleration, or changing the posture of the robot. Therefore, the adjustment parameters may be changed such as lowering them to approach 0 at low speed / low torque (emphasizing stable operation) and raising them to approach 1 at high speed / high torque (emphasizing the prevention of burnout).

[0056] In this way, the current command calculation unit 12 takes into account the d-axis component of the induced current and the suppression current to determine the command value of the d-axis current, making it easier to control the d-axis current of the motor 18 without having to perform any specific operations on the motor 18. In detail, as mentioned above, there are many parameters that affect the calculation of the d-axis current of the motor 18, making parameter setting difficult. However, while both too much and too little d-axis current cause problems, the degree of impact differs. Therefore, in this embodiment, the d-axis current is calculated with each parameter in a roughly adjusted state, and the increase or decrease of the d-axis current can be adjusted with a single parameter. As mentioned above, if the d-axis current is too high, the risk of failure such as winding burnout increases, and if the d-axis current is too low, the risk of control failure (inability to exert the required torque) due to exceeding the voltage condition range increases.

[0057] 3. Motor control method Next, the motor control method using the motor device 100 will be described with reference to Figure 7. Figure 7 is a flowchart showing an example of the motor control method according to this embodiment. The flowchart shown in Figure 7 is mainly executed by the current command calculation unit 12 (see Figure 3) of the current controller 101.

[0058] In Figure 7, the current command calculation unit 12 receives the speed command value input to the speed controller 11 or the actual rotor speed detection value of the motor 18 detected by the speed detector 22 (ST1). Based on the speed command value input to the speed controller 11 or the actual rotor speed detection value of the motor 18 detected by the speed detector 22, the current command calculation unit 12 estimates the q-axis and d-axis components of the induced current (see equation (1)) generated by the change in the magnetic field in the motor winding due to the rotational movement of the magnets on the rotor of the motor 18 (ST2).

[0059] The current command calculation unit 12 receives the torque command calculated by the speed controller 11 and calculates and generates a q-axis current command that includes a command value (Iq_ref) for the q-axis current corresponding to the rotational torque based on the torque command (ST3). The current command calculation unit 12 acquires the supply voltage of the inverter 17 (for example, a detected value corresponding to an actual measured value, or a fixed value) (ST4). Based on the detected or fixed value of the supply voltage of the inverter 17, the current command calculation unit 12 uses the q-axis component of the induced current from the induced current estimation unit 122 and the command value of the q-axis current indicated by the q-axis current command from the q-axis current command calculation unit 121 to estimate a suppressable current (see equation (2)) for causing the d-axis component of the induced current (see Figure 6(b)) to flow in a direction that suppresses or reduces it (ST5). The current command calculation unit 12 acquires adjustment parameters by referring to the storage unit 102 (ST6).

[0060] The current command calculation unit 12 calculates a suppression current (see equation (3)) whose absolute value is smaller than the suppression current by multiplying the suppression current estimated in step ST5 by the adjustment parameter obtained in step ST6 (ST7). The current command calculation unit 12 generates a d-axis current command (see equation (4)) which includes a command value for the d-axis current by adding the suppression current calculated in step ST7 and the d-axis component of the induced current estimated in step ST2 (ST8). As a result, the motor device 100 can more easily and appropriately control the d-axis current flowing through the rotor of the motor 18, taking into account the supply voltage supplied by the inverter 17 to the motor 18 and the rotational speed of the rotor of the motor 18, without having to make the motor perform any specific operation.

[0061] (Note) Based on the descriptions of the embodiments described above, the following technologies are disclosed.

[0062] (Item 1) An induction current estimation unit (122) estimates the induced current generated by the operation of the motor (18) based on a speed command value notified from an external source or the actual speed detected by a speed detector (22) that detects the rotational speed of the motor (18), A suppressable current estimation unit (123) estimates a suppressable current that flows in a direction that suppresses the d-axis component of the induced current, based on the q-axis component of the induced current and the q-axis current command value, A suppression current calculation unit (124) calculates a suppression current whose absolute value is smaller than the suppressable current based on predetermined parameters, The system includes a d-axis current command value calculation unit (125) that calculates a d-axis current command value based on the d-axis component of the induced current and the suppression current. Motor control device (101). This makes it easier for the motor control device to control the motor's d-axis current without requiring the motor to perform any specific actions.

[0063] (Item 2) The predetermined parameter is set based on at least one of the speed command value, the actual speed, and the q-axis current command value. Motor control device (101) as described in item 1. This allows the motor control device to more easily and effectively control the motor's d-axis current without requiring the motor to perform any specific actions.

[0064] (Item 3) The system further includes a voltage detection unit that detects the voltage supplied to the inverter (17) that controls the motor (18) and outputs the detected voltage value to the suppressable current estimation unit (123), The suppressable current estimation unit calculates the suppressable current based on the q-axis component of the induced current, the q-axis current command value, and the detected voltage value. A motor control device (101) as described in item 1 or 2. This makes it easier for the motor control device to control the motor's d-axis current without requiring the motor to perform any specific actions, even when detecting the voltage supplied to the inverter that controls the motor.

[0065] (Item 4) The predetermined parameters are set to values ​​in the range of 0 to 1, depending on the rotational speed and rotational torque required for the motor and at least one of the speed command value, the actual speed, and the q-axis current command value. Motor control device (101) as described in item 2. This allows the motor control device to appropriately set adjustment parameters for estimating the suppression current according to the rotational speed and rotational torque required for the motor and at least one of the speed command value, the actual speed, and the q-axis current command value.

[0066] (Item 5) Based on the speed command value notified from an external source or the actual speed detected by the speed detection unit that detects the rotational speed of the motor (18), the induced current generated by the operation of the motor (18) is estimated. Based on the q-axis component of the induced current and the q-axis current command value, the suppressable current that flows in the direction of suppressing the d-axis component of the induced current is estimated. Based on predetermined parameters, a suppression current is calculated whose absolute value is smaller than the suppressable current. Based on the d-axis component of the induced current and the suppression current, the d-axis current command value is calculated. Motor control method. This makes it easier to control the motor's d-axis current without having to perform any specific actions on the motor. [Industrial applicability]

[0067] This disclosure is useful as a motor control device and motor control method that makes it easier to control the d-axis current of a motor without having to perform specific operations on the motor. [Explanation of Symbols]

[0068] 11 Speed ​​controller 12 Current command calculation section 13 d-axis current controller 14. Q-axis current controller 15 Voltage Coordinate Transformation Unit 16 PWM calculation section 17 Inverter 18 Motors 19 Current detector 20 Current Coordinate Transformation Unit 21 Position detector 22 Speed ​​detector 100 Motor device 101 Current Controller 102 Storage section 121 q-axis current command calculation section 122 Induced current estimation section 123 Suppressable current estimator 124 Suppression current calculation section 125 d-axis current command value calculation unit

Claims

1. An induction current estimation unit estimates the induced current generated by the operation of the motor based on a speed command value notified from an external source or the actual speed detected by a speed detector that detects the rotational speed of the motor. A suppressable current estimation unit estimates a suppressable current that flows in a direction that suppresses the d-axis component of the induced current, based on the q-axis component of the induced current and the q-axis current command value. A suppression current calculation unit calculates a suppression current whose absolute value is smaller than the suppressable current based on predetermined parameters, The system includes a d-axis current command value calculation unit that calculates a d-axis current command value based on the d-axis component of the induced current and the suppression current. Motor control device.

2. The predetermined parameter is set based on at least one of the speed command value, the actual speed, and the q-axis current command value. The motor control device according to claim 1.

3. The system further includes a voltage detection unit that detects the voltage supplied to the inverter controlling the motor and outputs the detected voltage value to the suppressable current estimation unit, The suppressable current estimation unit calculates the suppressable current based on the q-axis component of the induced current, the q-axis current command value, and the detected voltage value. The motor control device according to claim 1 or 2.

4. The predetermined parameters are set to values ​​in the range of 0 to 1, depending on the rotational speed and rotational torque required for the motor and at least one of the speed command value, the actual speed, and the q-axis current command value. The motor control device according to claim 2.

5. Based on the speed command value notified from an external source or the actual speed detected by the speed detection unit that detects the motor's rotational speed, the induced current generated by the motor's operation is estimated. Based on the q-axis component of the induced current and the q-axis current command value, the suppressable current that flows in the direction of suppressing the d-axis component of the induced current is estimated. Based on predetermined parameters, a suppression current is calculated whose absolute value is smaller than the suppressable current. Based on the d-axis component of the induced current and the suppression current, the d-axis current command value is calculated. Motor control method.

Images