Motor control device

Abstract

Provided is a motor control device in which both shortening of the time required for designing and adjusting the correction amounts of an amplitude and a phase according to a response characteristic and securing a torque ripple suppression effect can be achieved. A motor control device 1 drives a motor 5 by means of an inverter 4. The motor control device 1 comprises: a harmonic control command value calculation unit 8 for obtaining a first harmonic control command value i* dqh, φ* dqh from a torque command value τ* and an electrical angle θe of the motor 5; a response compensation unit 9 for calculating a second harmonic control command value i ** dqh, φ** dqh obtained by performing response characteristic compensation corresponding to the rotational speed of the motor 5 on the first harmonic control command value i* dqh; and a voltage command calculation unit 3 for calculating a voltage command value v* dq on the basis of a control command for outputting the torque of the torque command value τ * and a second harmonic control command value i ** dqh, φ** dqh.

Description

Motor control device

[0001] The present invention relates to a motor control device that suppresses torque ripple generated from a motor during motor control.

[0002] Motors are becoming increasingly powerful for use in applications with limited loading space, such as automobiles. This has led to motors being used in an area where magnetic saturation occurs. In the magnetic saturation area, torque ripple increases, inducing vibration and noise, so torque ripple suppression control is particularly necessary.

[0003] A conventional device for suppressing motor torque ripple to reduce vibration is disclosed, for example, in Patent Document 1. The device described in Patent Document 1 creates a table relating to the amplitude and phase of torque ripple according to the torque generated by the motor, and by referring to this table, calculates a torque ripple compensation value corrected so as to suppress the amplitude and phase of the torque ripple, and superimposes this value on the command value. This correction makes it possible to suppress torque ripple at frequencies beyond the torque control band.

[0004] Patent No. 5784787

[0005] When correcting the amplitude and phase of the torque ripple compensation amount to be superimposed according to the rotation speed, it is necessary to know the response characteristics of the torque.

[0006] However, generally, the design response value of the FB controller and the actual torque response value will deviate due to changes in the motor constant caused by magnetic saturation at high torque, reducing the accuracy of torque ripple suppression.

[0007] Therefore, to ensure accuracy, it was necessary to adjust or measure the response characteristics for each operating condition, such as torque or current, which made designing the controller time-consuming.

[0008] The object of this invention is to provide a motor control device that can shorten the time required to design and adjust the amount of amplitude and phase correction according to the response characteristics while ensuring torque ripple suppression. The present invention uses a control system in the FB controller that has a robust response to changes in the motor constants, and individually corrects the phase and amplitude according to the rotation speed for the d- and q-axis harmonic command values.

[0009] In order to achieve the above object, the present invention is configured as follows.

[0010] A motor control device that drives a motor using an inverter includes: a harmonic control command value calculation unit that determines a first harmonic control command value from a torque command value and an electrical angle of the motor; a response compensation unit that calculates a second harmonic control command value by performing response characteristic compensation on the first harmonic control command value in accordance with the rotation speed of the motor; and a voltage command calculation unit that calculates a voltage command value based on a control command for outputting torque of the torque command value and the second harmonic control command value.

[0011] The present invention can provide a motor control device that can shorten the time required to design and adjust the amount of correction of amplitude and phase according to response characteristics, while also ensuring the effect of suppressing torque ripple.

[0012] It is a schematic block diagram of a motor control device according to a first embodiment of the present invention. It is a diagram showing a difference between an actual current and a detected current caused by a current detection delay. It is a schematic block diagram of a motor control device according to a second embodiment of the present invention. It is a diagram explaining conversion from current to magnetic flux. It is a diagram explaining conversion from current to magnetic flux.

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0014] First Embodiment FIG. 1 is a functional block diagram showing the configuration of a motor control device 1 according to a first embodiment of the present invention.

[0015] In the following description, the term "dq axes" refers to the "d axis and q axis." Furthermore, with respect to the subscripted parameters X (such as "i" and "v") described below, unless otherwise specified, "Xdq" refers to a "vector quantity (Xd, Xq)" and "Xuvw" refers to a "vector quantity (Xu, Xv, Xw)." Here, "uvw" refers to the three phases of AC, i.e., the "U phase, V phase, and W phase."

[0016] In FIG. 1, a motor control device 1 controls the speed and torque of a motor 5 by controlling the switching of an inverter 4 that supplies AC power to the motor 5 .

[0017] In the first embodiment, the motor control device 1 is configured by a processing unit such as a microcomputer, and functions as each unit by executing a predetermined program.

[0018] In this embodiment 1, the inverter 4 is a three-phase inverter having a three-phase full-bridge circuit as a main circuit, which is made up of semiconductor switching elements such as IGBTs and MOSFETs.

[0019] In the first embodiment, the motor 5 is a three-phase AC synchronous motor, which is a rotating machine, such as a permanent magnet synchronous motor.

[0020] The motor 5 is not limited to a synchronous machine, but may be an induction machine. The motor 5 is also not limited to a rotating machine, but may be a linear motor. The motor 5 may have a power generation function.

[0021] As shown in FIG. 1, the motor control device 1 calculates a torque command value 10 (τ ＊ ) is input, and the dq axis current command value 2 (i ＊ ｄｑ ), a voltage command calculation unit 3, an electrical angle detection unit 6, an electrical angular velocity calculation unit 7, a harmonic control command value calculation unit 8, a response compensation unit 9, a voltage command superposition unit 10, a voltage command value dq / three-phase axis converter 11, and a measurement current three-phase / dq axis converter 12.

[0022] The torque command value 10 is given from a higher-level controller or operation system.

[0023] The dq-axis current command value 2 is calculated as the dq-axis current required to output the torque of the given torque command from the motor 5. Generally, it is determined so that the torque output per current is maximized (MTPA), but the present invention is effective for any current.

[0024] The voltage command calculation unit 3 calculates the d-axis current detection value i ｄｑ and the dq axis current command value i ＊ ｄｑ The dq axis current detection value i ｄｑ is the dq axis current command value i ＊ ｄｑ The voltage command value v＊ ｄｑ Generate.

[0025] In the first embodiment, the voltage command calculation unit 3 is configured to connect integrators in series to the d and q axes of the motor inverse model of the following equation (1), and calculates the d and q axis current command value i ＊ ｄｑ (d-axis current command value i ＊ ｄ and the q-axis current command value i ＊ ｑ ) to obtain the voltage command value v ＊ ｄｑ is calculated. However, variables with a t at the end of the L subscript, which represents inductance, represent dynamic inductance, while variables without a t represent static inductance. Static inductance is a value determined by the ratio of the dq-axis current to the dq-axis magnetic flux, and dynamic inductance indicates the rate of change in magnetic flux near the reference current. When there is no magnetic saturation, the dynamic inductance and static inductance are the same, but when there is magnetic saturation, the dynamic inductance and static inductance do not match.

[0026]

[0027] In equation (1), Vd is the d-axis voltage of the motor 5, Vq is the q-axis voltage of the motor 5, R is the resistance value of the windings of the motor 5, Ld is the d-axis inductance of the motor 5, Lq is the q-axis inductance of the motor 5, Ldq and Lqd are the interference inductances between the d-axis and q-axis of the motor 5, Ke is the induced voltage constant, Ldt is the d-axis dynamic inductance of the motor 5, Lqt is the q-axis dynamic inductance of the motor 5, Ldqt and Lqdt are the dynamic interference inductances between the d-axis and q-axis of the motor 5, and i ＊ ｄ is the d-axis current command value, i ＊ ｑ is the q-axis current command value, ω ｅ is the electrical angular velocity of the motor 5.

[0028] The voltage command calculation unit 3 is not limited to the configuration of the first embodiment, and may use a control configuration obtained by equivalent transformation, or an approximation model that ignores terms with little influence. For example, if use in the magnetic saturation region is not expected, dynamic inductance and static inductance may be treated as equivalent values, or an integrator and a motor inverse model may be combined to form a PI controller and a decoupling controller.

[0029] The electrical angle detector 6 detects the electrical angle θ based on a rotation position signal from a rotation sensor (not shown) provided in the motor 5. ｅ The rotation sensor calculates and outputs the mechanical angle (θ ｍ ), the electrical angle detector 6 detects the number of pole pairs (p) of the motor 5 and the electrical angle θ ｅ and mechanical angle θ ｍ and the number of pole pairs (p) (θ ｅ = p θ ｍ ) to obtain the electrical angle θ ｅ Calculate.

[0030] The rotation sensor may be a mechanical angle resolver, a hall sensor, a rotary encoder, etc. Alternatively, a general position sensorless control method may be used to estimate the electrical angle from the current or voltage.

[0031] Similar to the electrical angle calculation unit 6, the electrical angular velocity calculation unit 7 calculates the electrical angular velocity ω based on a rotation position signal from a rotation sensor (not shown) provided in the motor 5. ｅ The electrical angle calculation unit 7 calculates and outputs the number of pole pairs (p) of the motor 5 and the electrical angle θ ｅ and mechanical angle θ ｍ and the relationship between p (θ ｅ = p θ ｍ ) and electrical angle θ ｅ and electrical angular velocity ω ｅ The relationship between (ω ｅ = dθ ｅ / dt) to obtain the electrical angular velocity ω ｅ The electrical angle velocity calculation unit 7 calculates the electrical angle θ output by the electrical angle calculation unit 6. ｅ Differentiate the electrical angular velocity ω ｅ It may also be comprised of a differentiator that calculates:

[0032] The harmonic control command value calculation unit 8 calculates the torque command value τ ＊ to the first harmonic control command value i ＊ ｄｑｈ Output.

[0033] The response compensation unit 9 includes a response compensation table or a response compensation function, and calculates the electrical angular velocity ω ｅ The first harmonic control command value i is calculated by the phase and amplitude correction amounts calculated from the response compensation table or response compensation function. ＊ ｄｑｈ The second harmonic control command value i ＊＊ ｄｑｈ Output.

[0034] The voltage command value dq / three-phase axis converter 11 (shown as dq / uvw in FIG. 1) is a voltage command value v output from the voltage command calculation unit 3. ＊ ｄｑ electrical angle θ ｅ The inverter 4 generates a signal for controlling the switching of the inverter 4 by converting the signal into a three-phase voltage according to the electrical angle θ ｅ Instead of θ, a delay time required for the voltage command value to be reflected in the inverter 4 is compensated. ｅｃ may also be used.

[0035] The measurement current three-phase / dq axis converter 12 converts the three-phase current detected by the current sensor into θ ｅ The dq axis current i ｄｑ In this case, θ ｅ Instead of θ, which takes into account the current detection delay ｅｄ may also be used.

[0036] The operation of the motor control device 1 will be described below, while the function of the present invention will be described.

[0037] First, the torque command value τ ＊ The harmonic control command value calculation unit 8 receives the input of the first harmonic control command value i as shown in the following equation (2): ＊ ｄｑｈ where n represents the order of the torque ripple.

[0038]

[0039] At this time, the dq axis current I ｄｑ, θ ｄｑ is calculated in advance by analysis or testing, and the torque command value τ ＊ It can be calculated using a table with θ as an argument. ｄｅｌａｙ is a manipulated variable that advances the phase by the delay time that occurs between the detected current and the current that actually flows through the motor 5, and the delay time is T ｄｅｌａｙ Then, nT ｄｅｌａｙ ω ｅ This operation allows the response and dead time of the FB controller to be separated, and the response compensation table described later can be designed as a simple first-order lag function.

[0040] If the delay is not corrected, even if the detected current and the current command value match, the actual current will deviate from the detected current as shown in Figure 2, causing a current with a phase different from the desired timing to flow, resulting in a degradation of performance. Note that in Figure 2, the detected current and the current command value are perfectly matched, but are deviated from each other for the sake of illustration.

[0041] dq axis current detection value I ｄｑ , θ ｄｑ By storing the coefficients as complex coefficients, it is possible to avoid phase discontinuity when referencing the table.

[0042] The response compensator 9 calculates the first harmonic control command value i ＊ ｄｑｈ For nω ｅ Furthermore, nω is calculated from the two-dimensional table of amplitude correction and electrical angle frequency, and the two-dimensional table of phase correction and each electrical frequency. ｅ The amplitude correction amount I corresponding to ｍｏｄ and the phase correction amount θ ｍｏｄ These two-dimensional tables can also be implemented as a function of the following equation (3) since the response is designed to be a first-order delay system in the first embodiment. However, in equation (3), ω ａｃｒ is the control response angular frequency.

[0043]

[0044] At this time, the second harmonic control command value i ＊＊ ｄｑｈ is calculated by the following equation (4).

[0045]

[0046] The voltage command calculation unit 3 calculates the second harmonic control command value i ＊＊ ｄｑｈ and the dq axis current command value i ＊ ｄｑ The final current command value calculated from the current measurement value and the voltage command value v ＊ ｄｑ Calculate.

[0047] When the control response angular frequencies of the d-axis and q-axis are designed to be different values, the torque response characteristics require the maintenance of a correction table for amplitude and phase for each combination of the control response characteristics of the d-axis and q-axis, which takes time to design. On the other hand, in the case of compensation for current, the response characteristics are determined for each axis, so different control response angular frequencies ω ａｃｒ It is only necessary to prepare a correction table or function for amplitude and phase for each, thereby reducing the number of design steps and ensuring the torque ripple suppression effect.

[0048] In addition, in this embodiment 1, the torque ripple of a single frequency is targeted in order to explain the operation, but it is also possible to deal with cases in which torque ripple of multiple frequencies is included by performing the same operation for each arbitrary order and adding up the results of all orders at the output stage of the response compensation unit 9. In this case, the response compensation unit 9 calculates the amplitude correction amount I ｍｏｄ and the phase correction amount θ ｍｏｄ is calculated for each order.

[0049] According to the first embodiment, it is possible to provide a motor control device that can shorten the time required to design and adjust the amount of correction of amplitude and phase according to response characteristics, while also ensuring the torque ripple suppression effect.

[0050] Second Embodiment Next, a second embodiment will be described.

[0051] The difference between the first embodiment and the second embodiment will be explained using the block diagram of the second embodiment shown in FIG.

[0052] In the second embodiment, the torque command value 10 (τ ＊ ), the control command calculation unit 13 outputs the dq axis current command value 2(i ＊ ｄｑ ) and calculate the dq axis current command value 2(i＊ ｄｑ ) is the magnetic flux command value φ ｄｑ and a converter 100 for converting the measured current i ｄｑ The measured magnetic flux value φ ｄｑ and a converter 101 for converting a torque command value 10 (τ ＊ ) by the following equation (5) from the harmonic current command value corresponding to ＊ ｄｑｈ is recorded, and the torque command value 10 (τ ＊ ) to the first harmonic control command value φ ＊ ｄｑｈ a harmonic control command value calculation unit 8 that outputs a first harmonic control command value φ ＊ ｄｑｈ and electrical angular velocity ω ｅ to the second harmonic control command value φ ＊＊ ｄｑｈ and a response compensator 9 for calculating a second harmonic control command value φ ＊＊ ｄｑｈ and the measured magnetic flux value φ ｄｑ (d-axis magnetic flux measurement value φ ｄ , q-axis magnetic flux measurement value φ ｑ ) to obtain the voltage command value v ＊ ｄｑ The voltage command calculation unit 3 calculates the voltage command.

[0053] The first harmonic control command value φ in the second embodiment ＊ ｄｑｈ and the second harmonic control command value φ ＊＊ ｄｑｈ The physical quantity of is a magnetic flux, unlike the current in the first embodiment. ｄ is the relationship between current and magnetic flux found by prior analysis, testing, etc., and is a function that depends on the currents on the d and q axes, as shown in Figures 4A and 4B. In this configuration, the converters 100 and 101 may use the same function, or in the case of tables, tables with different resolutions may be used depending on the required accuracy for the command value and the measured value.

[0054]

[0055]

[0056] In equation (6), Vd is the d-axis voltage of the motor 5, Vq is the q-axis voltage of the motor 5, R is the resistance value of the winding of the motor 5, Ld is the d-axis inductance of the motor 5, Lq is the q-axis inductance of the motor 5, Ldq and Lqd are the interference inductances between the d-axis and q-axis of the motor 5, Ke is the induced voltage constant, φ ｄ is the measured magnetic flux value of the d-axis, φ ｑ is the measured magnetic flux value of the q-axis, ω ｅ is the electrical angular velocity of the motor 5.

[0057] The operation of the second embodiment will be explained in comparison with the first embodiment. By using magnetic flux instead of current, the inverse model of the motor can reduce the number of variables as shown in equation (6) compared to equation (1) for current. This not only provides the same effect as the first embodiment, but also makes it possible to reduce the number of searches and the number of constant tables while taking into account nonlinearity due to magnetic saturation.

[0058] Furthermore, as with the first embodiment, the motor inverse model of equation (6) is not limited to the configuration of the second embodiment, and may be a control configuration obtained by equivalent transformation, or an approximate model that ignores terms with little influence.

[0059] 1... Motor control device, 2... dq axis current command value, 3... Voltage command calculation unit, 4... Inverter, 5... Motor, 6... Electrical angle detection unit, 7... Electrical angular velocity calculation unit, 8... Harmonic control command value calculation unit, 9... Response compensation unit, 10... Torque command value, 11... Voltage command value dq / three-phase axis converter, 12... Measurement current three-phase / dq axis converter, 13... Control command calculation unit, 100, 101... Converter, i ＊ ｄｑｈ , φ ＊ ｄｑｈ ...first harmonic control command value, i ＊＊ ｄｑｈ , φ ＊＊ ｄｑｈ ...second harmonic control command value, ω e ...electrical angular velocity

Claims

1. A motor control device that drives a motor using an inverter, comprising: a harmonic control command value calculation unit that determines a first harmonic control command value from a torque command value and the electrical angle of the motor; a response compensation unit that calculates a second harmonic control command value by performing response characteristic compensation on the first harmonic control command value in accordance with the rotation speed of the motor; and a voltage command calculation unit that calculates a voltage command value based on a control command for outputting torque of the torque command value and the second harmonic control command value.

2. A motor control device according to claim 1, wherein the harmonic control command value calculation unit calculates the first harmonic control command value for each order.

3. A motor control device according to claim 1, wherein the response compensation unit corrects the amplitude and phase of the first harmonic control command value for each order.

4. A motor control device according to claim 1, wherein the voltage command calculation unit calculates the following mathematical expression (1), where Vd is the d-axis voltage of the motor, Vq is the q-axis voltage of the motor, R is the resistance value of the motor windings, Ld is the d-axis inductance of the motor, Lq is the q-axis inductance of the motor, Ldq and Lqd are interference inductances between the d-axis and q-axis of the motor, Ke is an induced voltage constant, Ldt is the dynamic inductance of the motor's d-axis, Lqt is the dynamic inductance of the motor's q-axis, Ldqt and Lqdt are dynamic interference inductances between the d-axis and q-axis of the motor, i*d is the d-axis current command value, i*q is the q-axis current command value, and ωe is the electrical angular velocity of the motor. The motor control device according to claim 1, wherein the voltage command value is calculated using the above formula.

5. A motor control device according to claim 1, wherein the voltage command calculation unit calculates the following equation (6), where Vd is the d-axis voltage of the motor, Vq is the q-axis voltage of the motor, R is the resistance value of the motor windings, Ld is the d-axis inductance of the motor, Lq is the q-axis inductance of the motor, Ldq and Lqd are interference inductances between the d-axis and q-axis of the motor, Ke is an induced voltage constant, φd is the magnetic flux measurement value of the motor on the d-axis, φq is the magnetic flux measurement value of the motor on the q-axis, and ωe is the electrical angular velocity of the motor. The motor control device according to claim 1, wherein the voltage command value is calculated using the above formula.

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