Motor control device and electric power steering device

Abstract

This motor control device controls energization of a motor by vector control, and is provided with: a current command value calculation unit that generates a current command value in a dq coordinate system on the basis of a command value of the motor; a current command value limiting unit that limits the current command value of the dq coordinate system generated by the current command value calculation unit, and outputs a current limit command value that is the limited current command value of the dq coordinate system; and a controller that calculates a voltage command value for the motor by feedback control of the current limit command value, and the current command value limiting unit limits the current command value in the dq coordinate system on the basis of the DC bus voltage and the voltage command value. The operating point has the set voltage margin with respect to the voltage limit circle of the dq coordinate system.

Description

Technical Field

[0001] The present disclosure relates to a motor control device and an electric power steering device. Background Art

[0002] In recent years, a technique for suppressing abnormal noise and vibration of a motor by correcting a current command value so that the voltage is not saturated in current feedback control of a motor control device is known (for example, see Patent Document 1). In such a motor control device, by calculating the voltage saturation amount based on the target d-axis voltage and q-axis voltage, abnormal noise and vibration of the motor caused by voltage saturation can be appropriately suppressed even when three-phase modulation or two-phase modulation is performed. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent No. 6260502 Summary of the invention Technical problem to be solved by the invention

[0004] In the above-mentioned conventional motor control device, in order to suppress voltage saturation, the voltage command value is corrected so that the magnitude of the voltage vector is below the voltage protection value. That is, in the conventional motor control device, when the voltage protection value is exceeded, the shape of the voltage command value is forcibly corrected to the voltage protection value to suppress voltage saturation.

[0005] However, for example, when a certain voltage disturbance occurs near the voltage protection value and the voltage command value for suppressing the voltage disturbance exceeds the voltage protection value, in the conventional motor control device, the shape of the voltage command value is distorted to be below the voltage protection value, and it is difficult to suppress the voltage disturbance that occurs. In the conventional motor control device, there is a problem of abnormal noise and vibration of the motor caused by the voltage disturbance that occurs in this case.

[0006] The present disclosure is completed to solve the above-mentioned problems, and its purpose is to provide a motor control device and an electric power steering device that can suppress abnormal noise and vibration of the motor caused by voltage disturbance even when some voltage disturbance occurs at an operating point near a limited current command value. Technical means for solving technical problems

[0007] In order to solve the above-mentioned problems, one aspect of the present disclosure is a motor control device, which controls the power supply to the motor through vector control, including: a current command value calculation unit, which generates a current command value of a dq coordinate system based on the command value of the motor; a current command value limiting unit, which limits the current command value of the dq coordinate system generated by the current command value calculation unit, and outputs the current command value of the dq coordinate system after limitation, i.e., the current limiting command value; and a controller, which calculates a voltage command value for the motor through feedback control of the current limiting command value, and the current command value limiting unit limits the current command value of the dq coordinate system based on the DC bus voltage and the voltage command value, so that the action point has a set voltage margin relative to the voltage limit circle of the dq coordinate system.

[0008] In addition, one aspect of the present disclosure is an electric power steering device, comprising: the motor control device described above; the motor for assisting the steering of the steering gear; and a torque sensor for detecting the steering torque of the steering gear, the motor control device controlling the motor by using the assist instruction of the steering gear corresponding to the steering torque detected by the torque sensor as the instruction value of the motor. Effects of the Invention

[0009] According to the present disclosure, even when some voltage disturbance occurs at an operating point near a limited current command value, abnormal noise and vibration of the motor caused by the voltage disturbance can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a block diagram showing an example of the motor control device according to the first embodiment. Figure 2 1 is a block diagram showing an example of a current command value limiting unit in the first embodiment. Figure 3 This is the first diagram for explaining the operation of the motor control device in the first embodiment. Figure 4 This is a second diagram for explaining the operation of the motor control device in the first embodiment. Figure 5 This is a third diagram for explaining the operation of the motor control device in the first embodiment. Figure 6 This is a fourth diagram for explaining the operation of the motor control device in the first embodiment. Figure 7 This is a block diagram showing an example of a motor control device according to the second embodiment. Figure 81 is a block diagram showing an example of a current command value limiting unit in the second embodiment. Fig. 9 It is a diagram for explaining the operation of the motor control device in the third embodiment. Fig.10 This is a block diagram showing an example of an electric power steering device according to a fourth embodiment. Fig.11 This is a flowchart showing an example of the operation of the electric power steering device according to the fourth embodiment. DETAILED DESCRIPTION

[0011] Hereinafter, a motor control device and an electric power steering device according to an embodiment of the present disclosure will be described with reference to the drawings.

[0012] [Implementation Method 1] Figure 1 This is a block diagram showing an example of the motor control device according to the first embodiment. like Figure 1 As shown, the motor control device 1 includes a motor control unit 110, a motor position detector 2 and an inverter 5.

[0013] In the motor control device 1 , a DC power supply 3 is connected to a motor 10 , and energization of the motor 10 is controlled by vector control. The DC power source 3 is, for example, a battery, a DC-DC converter, a diode rectifier, a PWM (Pulse Width Modulation) rectifier, etc., and outputs a DC bus voltage Vdc to an inverter 5 described later. The DC power source 3 includes all devices that output a DC voltage.

[0014] The motor 10 is a multi-phase brushless motor, for example, a brushless motor having three-phase windings (U, V, W). The motor 10 is, for example, a permanent magnet synchronous motor, a film-wire synchronous motor, an induction motor, a synchronous reluctance motor, or the like.

[0015] The motor position detector 2 detects the motor position θ of the motor 10 using, for example, a resolver, an encoder, an MR sensor, or the like.

[0016] The inverter 5 applies an AC voltage to three-phase windings (U, V, W) of the motor 10 based on the DC bus voltage Vdc output from the DC power supply 3. The inverter 5 applies a three-phase AC voltage to the motor 10 based on the switching signals GS1 to GS6 as control signals.

[0017] Furthermore, the inverter 5 includes switching elements 51 to 56 . Each of the switching elements 51 to 56 is a semiconductor switch such as an IGBT (Insulated Gate Bipolar Transistor), a bipolar transistor, or a MOS (Metal Oxide Semiconductor) power transistor. In addition, a diode (or body diode) is connected in reverse parallel to each of the switching elements 51 to 56.

[0018] The switching elements 51 , 53 , and 55 are switching elements of the upper arm (high potential side), and the switching elements 52 , 54 , and 56 are switching elements of the lower arm (low potential side).

[0019] In addition, the above-mentioned switching signal GS1, switching signal GS3 and switching signal GS5 are control signals for turning on and off (making them in a conducting state or a non-conducting state) the switching elements 51, 53 and 55 of the upper arm (high potential side).

[0020] In addition, the above-mentioned switching signal GS2, switching signal GS4 and switching signal GS6 are control signals for turning on and off (making them in a conducting state or a non-conducting state) the switching elements 52, 54 and 56 of the lower arm (low potential side).

[0021] To each of the switching element 52 , the switching element 54 , and the switching element 56 as the switching elements of the lower arm, the shunt resistors 41 to 43 connected in series are connected.

[0022] Shunt resistors 41 to 43 are current detection resistors, and output voltages VRu, VRv, and VRw proportional to currents iu, iv, and iw flowing through the motor 10. Here, voltages VRu, VRv, and VRw are represented by the following equation (1).

[0023] [Mathematical formula 1] In addition, each of the resistance value Ru, the resistance value Rv, and the resistance value Rw represents the resistance value of the shunt resistors 41 to 43 . The shunt resistors 41 to 43 output the voltages VRu, VRv, and VRw shown in the equation (1) to the motor control unit 110 . Furthermore, the inverter 5 may be integrated with the electric motor 10 .

[0025] The motor control unit 110 receives as input the torque command T_ref (an example of the command value of the motor 10) as a control command from the outside, the voltage VRu, the voltage VRv, the voltage VRw, and the motor position θ, and outputs the switching signals GS1 to GS6. The motor control unit 110 is, for example, a PWM controller that outputs the switching signals GS1 to GS6 through a discrete time operator such as a microcomputer or a DSP (digital signal processor).

[0026] The motor control unit 110 includes a DC bus voltage detection unit 6, a current command value calculation unit 7, a current command value limiting unit 8, a speed calculator 9, a three-phase / two-phase coordinate converter 11, a controller 12, a current detector 13, a two-phase / three-phase coordinate converter 14, a correction voltage generator 15, a PWM signal generator 16 and a voltage margin calculation unit 17.

[0027] The DC bus voltage detection unit 6 detects the DC bus voltage Vdc using, for example, a voltage sensor, a resistor divider, etc. By detecting the DC bus voltage Vdc by the DC bus voltage detection unit 6, the motor control unit 110 can perform motor control corresponding to the DC bus voltage fluctuation.

[0028] Furthermore, for the purpose of reducing costs by reducing the number of sensors for detection, the DC bus voltage detection unit 6 may output the DC bus voltage Vdc as a fixed value (for example, Vdc=12 V).

[0029] The speed calculator 9 detects the rotational angular velocity ω of the motor 10 based on the motor position θ of the motor 10 detected by the motor position detector 2 . The speed calculator 9 outputs the detected rotational angular velocity ω to the current command value calculation unit 7 .

[0030] The current command value calculation unit 7 generates the current command value (d-axis current command value Id* and q-axis current command value Iq*) of the dq coordinate system based on the command value of the motor 10. The current command value calculation unit 7 calculates the q-axis current command value Iq* and the d-axis current command value Id* using the command value of the motor 10, i.e., the torque command T_ref as a control command, the DC bus voltage Vdc detected by the DC bus voltage detection unit 6, the motor position θ, and the rotational angular velocity ω of the motor 10 output by the speed calculation unit 9.

[0031] In order to ensure a specific voltage margin set with respect to the voltage limit circle R1 based on the DC bus voltage Vdc, the voltage margin calculation unit 17 (an example of a voltage margin setting unit) outputs the voltage utilization coefficient K as a value representing the voltage margin to the current command value limiting unit 8. Here, the voltage limit circle R1 is a voltage limit circle in the dq coordinate system, and the size of the voltage limit circle R1 is expressed by the following formula (2).

[0032] [Mathematical formula 2] Furthermore, using the voltage utilization factor K, the voltage margin is defined by the following equation (3).

[0034] [Mathematical formula 3] The voltage margin calculation unit 17 sets the voltage utilization coefficient K to set the voltage margin according to the equation (3). The voltage utilization coefficient K may be a variable value between 0 and 1, for example. As shown in equation (3), the voltage margin is variably set according to the DC bus voltage Vdc. That is, the voltage margin calculation unit 17 variably changes the voltage utilization coefficient K to variably set the voltage margin.

[0036] The current command value limiting unit 8 limits the current command value (d-axis current command value Id* or / and q-axis current command value Iq*) of the dq coordinate system generated by the current command value calculation unit 7, and outputs the current limit command value (limited d-axis current command value Id** or / and limited q-axis current command value Iq**) as the limited current command value of the dq coordinate system. For example, the current command value limiting unit 8 limits the current command value (d-axis current command value Id* or / and q-axis current command value Iq*) of the dq coordinate system based on the DC bus voltage Vdc detected by the DC bus voltage detection unit 6, the voltage utilization coefficient K output by the voltage margin calculation unit 17, and the voltage command value (voltage command value Vd* and voltage command value Vq*) obtained from the controller 12, so that the operating point has a set voltage margin with respect to the voltage limit circle R1 of the dq coordinate system.

[0037] That is, the current command value of the dq coordinate system includes the d-axis current command value and the q-axis current command value. The current command value limiting unit 8 limits at least one of the d-axis current command value Id* and the q-axis current command value Iq* based on the DC bus voltage Vdc detected by the DC bus voltage detection unit 6 and the voltage command value (voltage command value Vd* and voltage command value Vq*) so that the operating point has a voltage margin with respect to the voltage limit circle R1. Here, we will refer to Figure 2 The configuration of the current command value limiting unit 8 will be described in detail.

[0038] Figure 2 : is a block diagram showing an example of the current command value limiting unit 8 in the present embodiment. like Figure 2As shown, the current command value limiting unit 8 includes a dq axis voltage calculator 81 , a limit voltage calculator 82 , subtractors ( 83 , 85 , 86 ), an integration calculator 84 , a current command value limiter 87 , and a current command value limiter 88 .

[0039] The dq axis voltage calculator 81 calculates the magnitude Vdq* of the composite voltage vector based on the voltage command value Vd* and the voltage command value Vq*. The magnitude Vdq* of the composite voltage vector is expressed by the following equation (4).

[0040] [Formula 4]

[0041] That is, the dq-axis voltage calculator 81 calculates the magnitude Vdq* of the composite voltage vector using equation (4). The dq-axis voltage calculator 81 outputs the calculated magnitude Vdq* of the composite voltage vector to the subtractor 83 .

[0042] The voltage limiting calculator 82 calculates the size of the voltage limiting circle R2 based on the voltage utilization coefficient K and the DC bus voltage Vdc. The voltage limiting circle R2 is a voltage limiting circle in the dq coordinate system, and the size of the voltage limiting circle R2 is expressed by the following equation (5).

[0043] [Mathematical formula 5]

[0044] That is, the limit voltage calculator 82 calculates the size of the voltage limit circle R2 using the equation (5). The limit voltage calculator 82 outputs the calculated size of the voltage limit circle R2 to the subtractor 83.

[0045] The subtractor 83 calculates the difference (deviation ΔVdq) between the output of the dq axis voltage calculator 81 and the output of the limit voltage calculator 82. That is, the subtractor 83 calculates the difference (deviation ΔVdq) between the magnitude Vdq* of the combined voltage vector and the magnitude of the voltage limit circle R2, and outputs it to the integrator 84.

[0046] The integral operator 84 outputs the d-axis current integral value Id_sum and the q-axis current integral value Iq_sum obtained by integrating the deviation ΔVdq based on the deviation ΔVdq output by the subtractor 83. The integral operator 84 feeds back and adds the delayed values ​​of the d-axis current integral value Id_sum and the q-axis current integral value Iq_sum to the output obtained by multiplying the deviation ΔVdq output by the subtractor 83 by the integral gain Kid and the integral gain Kiq in the respective axis directions of the dq axis. In addition, the integral operator 84 outputs the d-axis current integral value Id_sum and the q-axis current integral value Iq_sum by current limiting the added value. The integrator operator 84 includes an amplifier 841 , an amplifier 845 , an adder 842 , an adder 846 , a current limiter 843 , a current limiter 847 , a delay element 844 , and a delay element 848 .

[0047] The amplifier 841 amplifies the deviation ΔVdq with an integral gain Kid and outputs it to the adder 842 . The adder 842 adds the output of the delay element 844 and the output of the amplifier 841 , and outputs the result to the current limiter 843 .

[0048] The current limiter 843 is a current limiter for the d-axis, and limits the upper limit of the output of the adder 842 to the d-axis current upper limit value Id_MAX and the lower limit to the d-axis current lower limit value Id_MIN, and outputs a d-axis current integrated value Id_sum. Furthermore, the delay element 844 delays the output of the current limiter 843 (the d-axis current integrated value Id_sum), and outputs the delay to the adder 842 .

[0049] In this way, the integral operator 84 generates the d-axis current integrated value Id_sum obtained by integrating the deviation ΔVdq using the amplifier 841 , the adder 842 , the current limiter 843 , and the delay element 844 . In addition, the amplifier 845 amplifies the deviation ΔVdq using the integral gain Kid and outputs it to the adder 846 . The adder 846 adds the output of the delay element 848 and the output of the amplifier 845 , and outputs the result to the current limiter 847 .

[0051] The current limiter 847 is a current limiter for the q-axis, and limits the upper limit of the output of the adder 846 to the q-axis current upper limit value Iq_MAX and the lower limit to the q-axis current lower limit value Iq_MIN, and outputs the q-axis current integrated value Iq_sum. Furthermore, the delay element 848 delays the output of the current limiter 847 (the q-axis current integrated value Iq_sum), and outputs the delay to the adder 846 .

[0052] In this way, the integral operator 84 generates the q-axis current integrated value Iq_sum obtained by integrating the deviation ΔVdq using the amplifier 845 , the adder 846 , the current limiter 847 , and the delay element 848 .

[0053] The subtractor 85 calculates the difference between the d-axis current upper limit value Id_MAX of the dq axis and the d-axis current integrated value Id_sum outputted from the integral calculator 84 , and outputs the difference as the d-axis current limit value Id_limit to the current command value limiter 87 .

[0054] The subtractor 86 calculates the difference between the dq-axis q-axis current upper limit value Iq_MAX and the q-axis current integrated value Iq_sum output by the integral calculator 84 , and outputs the difference as the q-axis current limit value Iq_limit to the current command value limiter 88 .

[0055] The current command value limiter 87 limits the d-axis current command value Id* based on the d-axis current limit value Id_limit output by the subtracter 85, and outputs the limited d-axis current command value Id**. When limiting the d-axis current command value Id*, the current command value limiter 87 limits the upper limit to the d-axis current limit value Id_limit and the lower limit to the d-axis current lower limit value Id_MIN.

[0056] The current command value limiter 88 limits the q-axis current command value Iq* based on the q-axis current limit value Iq_limit outputted from the subtracter 86, and outputs the limited q-axis current command value Iq**. When limiting the q-axis current command value Iq*, the current command value limiter 88 limits the upper limit to the q-axis current limit value Iq_limit and limits the lower limit to the negative value (-Iq_limit) of the q-axis current limit value Iq_limit.

[0057] Back to Figure 1 As described above, the current detector 13 detects the detection current (ius, ivs, iws) using the voltage (VRu, VRv, VRw) across the shunt resistor (41, 42, 43) of each of the switching elements (52, 54, 56) connected in series to the lower arm of the inverter 5 and the switching signals GS1 to GS6. The current detector 13 outputs the detected detection current (ius, ivs, iws) to the three-phase / two-phase coordinate converter 11.

[0058] The three-phase / two-phase coordinate converter 11 converts the detected current (ius, ivs, iws) detected by the current detector 13 and the motor position θ detected by the motor position detector 2 into dq axis coordinates, and calculates the d-axis detected current Id and the q-axis detected current Iq. The three-phase / two-phase coordinate converter 11 outputs the calculated d-axis detected current Id and q-axis detected current Iq to the controller 12.

[0059] The controller 12 calculates the voltage command values ​​(voltage command value Vd* and voltage command value Vq*) on the dq axes of the motor 10 by feedback control of the current limit command values ​​(limited d-axis current command value Id** and limited q-axis current command value Iq**). For example, the controller 12 calculates the voltage command value Vd* and voltage command value Vq* based on the limited d-axis current command value Id** and limited q-axis current command value Iq**, the d-axis detection current Id, and the q-axis detection current Iq.

[0060] Furthermore, the controller 12 includes subtractors 121 and 123 , a d-axis controller 122 , and a q-axis controller 124 .

[0061] The subtractor 121 calculates a deviation (d-axis current deviation) between the voltage command value Vd* outputted from the current command value limiting unit 8 and the d-axis detection current Id. The subtractor 121 outputs the deviation (d-axis current deviation) to the d-axis controller 122 .

[0062] The subtractor 123 calculates a deviation (q-axis current deviation) between the voltage command value Vq* outputted from the current command value limiting unit 8 and the q-axis detection current Iq. The subtractor 123 outputs the deviation (q-axis current deviation) to the q-axis controller 124 .

[0063] The d-axis controller 122 calculates the voltage command value Vd* by using a control method such as P control or PI control so that the d-axis current deviation becomes “0” (zero). The d-axis controller 122 outputs the calculated voltage command value Vd* to the current command value limiting unit 8 and the two-phase / three-phase coordinate converter 14 .

[0064] The q-axis controller 124 calculates the voltage command value Vq* by using a control method such as P control or PI control so that the q-axis current deviation becomes “0” (zero). The q-axis controller 124 outputs the calculated voltage command value Vq* to the current command value limiter 8 and the two-phase / three-phase coordinate converter 14 .

[0065] The two-phase / three-phase coordinate converter 14 performs coordinate conversion based on the voltage command value Vd* and the voltage command value Vq* and the motor position θ detected by the motor position detector 2, and calculates the voltage command values ​​on the three-phase coordinates (u-phase voltage command value vu, v-phase voltage command value vv, w-phase voltage command value vw). The two-phase / three-phase coordinate converter 14 outputs the calculated voltage command values ​​on the three-phase coordinates (u-phase voltage command value vu, v-phase voltage command value vv, w-phase voltage command value vw) to the correction voltage generator 15.

[0066] The correction voltage generator 15 switches the u-phase voltage command value vu, the v-phase voltage command value vv and the w-phase voltage command value vw output by the two-phase / three-phase coordinate converter 14 to improve the voltage utilization rate to (2 / 3 1 / 2 ) times the modulation method is used to equally add the offset voltage Voffset to the three phases, thereby generating the correction voltage command values ​​(u-phase correction voltage command value vu', v-phase correction voltage command value vv', w-phase correction voltage command value vw'). The correction voltage generator 15 outputs the generated correction voltage command values ​​(u-phase correction voltage command value vu', v-phase correction voltage command value vv', and w-phase correction voltage command value vw') to the PWM signal generator 16.

[0067] In addition, since the modulation method that can improve the voltage utilization rate by applying the offset voltage Voffset in the correction voltage generator 15 is a known technology, its description is omitted here. In addition, when the motor control unit 110 is configured not to include the correction voltage generator 15, Figure 2 The limit voltage calculator 82 shown can calculate the size of the voltage limit circle R2 using the following equation (6).

[0068] [Mathematical formula 6]

[0069] The PWM signal generator 16 generates switching signals GS1 to GS6 for driving the inverter 5 based on the correction voltage command values ​​(u-phase correction voltage command value vu', v-phase correction voltage command value vv', w-phase correction voltage command value vw') output by the correction voltage generator 15. The PWM signal generator 16 outputs the switching signals GS1 to GS6 as control signals for PWM control to the inverter 5.

[0070] Next, the operation of the motor control device 1 according to the present embodiment will be described with reference to the drawings. Figure 3 and Figure 4 1 is a diagram showing an example of the operation of the motor control device 1 according to the present embodiment. Figure 3 and Figure 4 A phasor diagram based on a known voltage equation of a motor is shown, and for simplicity of explanation, the explanation will be made assuming a state in which the current command value is limited for each axis.

[0071] Figure 3 The phasor diagram shown in FIG. 1 shows an operating point P1 where no current command value limitation is performed. Figure 4 The phasor diagram shown shows the operating point P2 when the q-axis current command value Iq* is limited to the q-axis current command value Iq**, so that Figure 3 The operating point P1 of the voltage regulator becomes an operating point with a set voltage margin. Figure 3 and Figure 4 Comparison of the two graphs shows that by limiting the q-axis current command value Iq* to the limited q-axis current command value Iq**, the vector of the terms (ωLqIq*, RIq*) related to the q-axis current command value Iq* is shortened.

[0072] Thus, in the motor control device 1 of this embodiment, by limiting the q-axis current command value Iq* to the limited q-axis current command value Iq**, the operating point can be changed from the operating point P1 to the operating point P2, and the operating point can be made an operating point having a set voltage margin.

[0073] also, Figure 5 and Figure 6 1 is a diagram showing another example of the operation of the motor control device 1 according to the present embodiment. Figure 5 and Figure 6 A phasor diagram based on a known voltage equation of a motor is shown, and for simplicity of explanation, the explanation will be made assuming a state in which the current command value is limited for each axis. Figure 5 The phasor diagram shown in FIG. 1 shows an operating point P3 where no current command value limitation is performed. Figure 6 The phasor diagram shown shows an operating point P4 when the d-axis current command value Id* is limited to the limited d-axis current command value Id**, so that Figure 5 The operating point P3 shown becomes an operating point having a set voltage margin. Figure 5 and Figure 6 Comparison of the two graphs shows that by limiting the d-axis current command value Id* to the limited d-axis current command value Id**, the vector of the terms (ωLdId*, RId*) related to the d-axis current command value Id* is extended.

[0075] Thus, in the motor control device 1 of this embodiment, by limiting the d-axis current command value Id* to the limited d-axis current command value Id**, the operating point can be changed from the operating point P3 to the operating point P4, and the operating point can be made an operating point having a set voltage margin.

[0076] In addition, in the motor control device 1 of the present embodiment, as described above, not only one of the d-axis and the q-axis can be changed, but also both the d-axis and the q-axis can be restricted to change the operating point. In this case, the change of the operating point is the above Figure 4 and Figure 6 combination.

[0077] As described above, the motor control device 1 of the present embodiment is a motor control device that controls the energization of the motor 10 by vector control, and includes a current command value calculation unit 7, a current command value limiting unit 8, and a controller 12. The current command value calculation unit 7 generates a current command value (d-axis current command value Id* and q-axis current command value Iq*) of the dq coordinate system based on a command value (e.g., a torque command T_ref) of the motor 10. The current command value limiting unit 8 limits the current command value (d-axis current command value Id* and q-axis current command value Iq*) of the dq coordinate system generated by the current command value calculation unit 7, and outputs a current limit command value (limited d-axis current command value Id** and limited q-axis current command value Iq**) as the limited current command value of the dq coordinate system. The controller 12 calculates a voltage command value (voltage command value Vd* and voltage command value Vq*) for the motor 10 by feedback control of the current limit command value (limited d-axis current command value Id** and limited q-axis current command value Iq**). The current command value limiting unit 8 limits the current command value of the dq coordinate system (d-axis current command value Id* and / or q-axis current command value Iq*) based on the DC bus voltage Vdc and the voltage command value (voltage command value Vd* and voltage command value Vq*) so that the operating point has a set voltage margin relative to the voltage limit circle R1 of the dq coordinate system.

[0078] Thus, the motor control device 1 of the present embodiment limits the current command value (d-axis current command value Id* and q-axis current command value Iq*) so that the operating point has a voltage margin relative to the voltage limit circle R1, so that voltage saturation does not occur within the range of the voltage margin from the operating point. In addition, even if some voltage disturbance occurs at the operating point near the limited current command value, the motor control device 1 of the present embodiment does not need to perform correction to make the voltage below the voltage protection value as in the prior art, but can ensure the fluctuation amplitude as the voltage margin. Therefore, in the motor control device 1 of the present embodiment, the shape of the voltage command value that can suppress the voltage disturbance that occurs can be maintained. As a result, the motor control device 1 of the present embodiment can not only suppress voltage saturation, but also suppress abnormal noise and vibration of the motor caused by voltage disturbance even if some voltage disturbance occurs at the operating point near the limited current command value.

[0079] In addition, the motor control device 1 of the present embodiment includes a DC bus voltage detection unit 6 for detecting a DC bus voltage Vdc. The current command value of the dq coordinate system includes a d-axis current command value Id* and a q-axis current command value Iq*. The current command value limiting unit 8 limits at least one of the d-axis current command value Id* and the q-axis current command value Iq* based on the DC bus voltage Vdc detected by the DC bus voltage detection unit 6 and the voltage command value (voltage command value Vd* and voltage command value Vq*) so that the operating point has a voltage margin relative to the voltage limit circle R1. Therefore, since the motor control device 1 of this embodiment limits at least one of the d-axis current command value Id* and the q-axis current command value Iq* based on the DC bus voltage Vdc, it can respond appropriately when the DC bus voltage Vdc changes, thereby suppressing abnormal noise and vibration of the motor caused by voltage interference.

[0081] In addition, in the present embodiment, the controller 12 outputs the voltage command value (voltage command value Vd* and voltage command value Vq*) of the dq coordinate system as the voltage command value. The current command value limiting unit 8 limits at least one of the d-axis current command value and the q-axis current command value based on the deviation ΔVdq between the magnitude of the voltage vector represented by the voltage command value (voltage command value Vd* and voltage command value Vq*) of the dq coordinate system and the calculated value calculated based on the DC bus voltage Vdc and the value K representing the voltage margin.

[0082] Thus, in the motor control device 1 of the present embodiment, by using the voltage command values ​​of the dq coordinate system (voltage command value Vd* and voltage command value Vq*) as voltage command values, abnormal noise and vibration of the motor caused by voltage disturbance can be suppressed by a simple method.

[0083] Furthermore, in the present embodiment, the current command value limiting unit 8 limits at least one of the d-axis current command value and the q-axis current command value based on the integrated value of the deviation ΔVdq.

[0084] Therefore, the motor control device 1 of this embodiment can suppress a sudden change in the current limit command value (the limited d-axis current command value Id** and the limited q-axis current command value Iq**) by limiting using the integral value, and can more appropriately suppress abnormal noise and vibration of the motor 10.

[0085] The motor control device 1 of the present embodiment includes a voltage margin calculation unit 17 (voltage margin setting unit) that variably sets a voltage margin. The current command value limiter 8 limits the current command value in the dq coordinate system based on the voltage margin set by the voltage margin calculation unit 17 .

[0086] Thus, the motor control device 1 of the present embodiment can more appropriately suppress abnormal noise and vibration of the motor 10 by variably setting the voltage margin according to the operating state of the motor 10 , for example.

[0087] Furthermore, in the present embodiment, the voltage margin is set based on the DC bus voltage Vdc (see the above-mentioned equation (3)). Thus, in the motor control device 1 of the present embodiment, the voltage margin is set based on the DC bus voltage Vdc, and therefore the voltage margin can be appropriately changed and set in accordance with the DC bus voltage Vdc.

[0088] [Implementation Method 2] Next, a motor control device 1 a according to Embodiment 2 will be described with reference to the drawings.

[0089] Figure 7 This is a block diagram showing an example of a motor control device 1 a according to the second embodiment. like Figure 7 As shown, the motor control device 1a includes a motor control unit 110a, a motor position detector 2, and an inverter 5. The motor control unit 110a includes a DC bus voltage detection unit 6, a current command value calculation unit 7, a current command value limiter 8a, a speed calculator 9, a three-phase / two-phase coordinate converter, a controller 12a, a current detector 13, a PWM signal generator 16, and a voltage margin calculation unit 17.

[0090] The present embodiment is different from the first embodiment in that the processing of the current command value limiting unit 8 a is different; and the controller 12 a includes a two-phase / three-phase coordinate converter 14 and a correction voltage generator 15 a . In addition, Figure 7 In the above Figure 1 The same structures are given the same reference numerals, and their description is omitted.

[0091] The controller 12a outputs as voltage command values ​​the phase voltage command values ​​corresponding to the respective phases of the three-phase windings (U, V, W) of the motor 10. The controller 12a outputs as phase voltage command values ​​the corrected voltage command values ​​(u-phase corrected voltage command value vu', v-phase corrected voltage command value vv', w-phase corrected voltage command value vw').

[0092] Furthermore, the controller 12 a includes subtractors 121 and 123 , a d-axis controller 122 , a q-axis controller 124 , a two-phase / three-phase coordinate converter 14 , and a correction voltage generator 15 a .

[0093] The correction voltage generator 15a switches the u-phase voltage command value vu, the v-phase voltage command value vv and the w-phase voltage command value vw output by the two-phase / three-phase coordinate converter 14 to a voltage command value that can improve the voltage utilization rate to (2 / 3 1 / 2 ) times the modulation method is used to equally add the offset voltage Voffset to the three phases. The correction voltage generator 15a further equally adds the compensation voltage Vcomp for a certain interference voltage to the three phases, thereby generating correction voltage command values ​​(u-phase correction voltage command value vu', v-phase correction voltage command value vv', w-phase correction voltage command value vw').

[0094] Here, the compensation voltage Vcomp is, for example, a dead time compensation voltage or a compensation voltage for suppressing a specific order component. The correction voltage generator 15 a outputs the generated correction voltage command values ​​(u-phase correction voltage command value vu′, v-phase correction voltage command value vv′, and w-phase correction voltage command value vw′) to the PWM signal generator 16 .

[0095] The current command value limiting unit 8a limits the current command value (d-axis current command value Id* or / and q-axis current command value Iq*) of the dq coordinate system generated by the current command value calculation unit 7, and outputs the current limit command value (limited d-axis current command value Id** or / and limited q-axis current command value Iq**) as the limited current command value of the dq coordinate system. For example, the current command value limiting unit 8a limits the current command value (limited d-axis current command value Id** or / and limited q-axis current command value Iq**) of the dq coordinate system based on the DC bus voltage Vdc detected by the DC bus voltage detection unit 6, the voltage utilization coefficient K output by the voltage margin calculation unit 17, and the corrected voltage command value (u-phase corrected voltage command value vu', v-phase corrected voltage command value vv', w-phase corrected voltage command value vw') obtained from the controller 12a so that the operating point has a set voltage margin with respect to the voltage limit circle R1 of the dq coordinate system. Here, we will refer to Figure 8 The configuration of the current command value limiting unit 8a will be described in detail.

[0096] Figure 8 2 is a block diagram showing an example of the current command value limiting unit 8 a in the present embodiment. like Figure 8 As shown, the current command value limiting unit 8a includes a dq axis voltage calculator 81a, a limit voltage calculator 82, subtractors (83, 85, 86), an integration calculator 84, a current command value limiter 87 and a current command value limiter 88.

[0097] The dq axis voltage calculator 81a calculates the magnitude Vdq* of the composite voltage vector based on the correction voltage command values ​​(u-phase correction voltage command value vu', v-phase correction voltage command value vv' and w-phase correction voltage command value vw'). The magnitude Vdq* of the composite voltage vector is expressed by the following equation (7). [Mathematical formula 7]

[0099] That is, the dq-axis voltage calculator 81 a calculates the magnitude Vdq* of the composite voltage vector using equation (7). The dq-axis voltage calculator 81 a outputs the calculated magnitude Vdq* of the composite voltage vector to the subtractor 83 . The other configurations are the same as those of the current command value limiting unit 8 in the first embodiment, and therefore description thereof will be omitted here.

[0100] As described above, in the present embodiment, the controller 12a outputs as voltage command values ​​the phase voltage command values ​​(u-phase corrected voltage command value vu', v-phase corrected voltage command value vv', w-phase corrected voltage command value vw') corresponding to each phase of the three-phase winding (U, V, W) of the motor 10. The current command value limiting unit 8a limits at least one of the d-axis current command value Id* and the q-axis current command value Iq* based on the deviation ΔVdq between the magnitude of the composite voltage vector of each inter-phase voltage calculated based on each corresponding phase voltage command value (u-phase corrected voltage command value vu', v-phase corrected voltage command value vv', w-phase corrected voltage command value vw'). Therefore, the motor control device 1a of this embodiment uses the phase voltage command values ​​of each phase (u-phase corrected voltage command value vu', v-phase corrected voltage command value vv', w-phase corrected voltage command value vw') as the voltage command value. Even when voltage interference occurs or a compensation voltage is applied after, for example, two-phase / three-phase coordinate conversion, it is possible to limit the current command value taking these factors into account.

[0102] [Implementation method 3] Next, a motor control device 1 (1a) according to Embodiment 3 will be described with reference to the drawings. In this embodiment, a modification example in which the voltage utilization coefficient K calculated by the voltage margin calculation unit 17 is made variable in the motor control device 1 (1a) according to Embodiments 1 and 2 will be described.

[0103] Fig. 9 It is a diagram for explaining the operation of the motor control device 1 ( 1 a ) according to the third embodiment. exist Fig. 9In FIG. 1 , a waveform W1 represents a change in the DC bus voltage Vdc, and a waveform W2 represents a change in the voltage utilization factor K. In addition, the horizontal axis of each graph represents time.

[0104] like Fig. 9 As shown, the voltage margin calculation unit 17 of the present embodiment changes the value indicating the voltage margin (voltage utilization coefficient K) based on the DC bus voltage Vdc. For example, in Fig. 9 At time t1, when the DC bus voltage Vdc is lower than the abnormality determination value Vab (is lower than the abnormality determination value Vab), the voltage margin calculation unit 17 smoothly changes the voltage utilization coefficient K from the preset specific value K1 to "1.0".

[0105] Furthermore, when changing the voltage utilization factor K, the voltage margin calculation unit 17 provides a transition period to change the voltage margin (voltage utilization factor K) so that the voltage margin (voltage utilization factor K) changes smoothly.

[0106] Here, “smoothly” does not mean taking discrete values ​​such as “0” or “1”, but means, for example, changing continuously between “0” and “1”.

[0107] In addition, Fig. 9 When the DC bus voltage Vdc exceeds the abnormality determination value Vab at time t2, the voltage margin calculation unit 17 smoothly changes the voltage utilization coefficient K from "1.0" to a preset specific value K1.

[0108] As described above, in the present embodiment, the voltage margin calculation unit 17 (voltage margin setting unit) changes the voltage margin (voltage utilization coefficient K) based on the DC bus voltage Vdc. Thus, the motor control device 1 (1a) of the present embodiment can appropriately change the voltage margin (voltage utilization factor K) according to the DC bus voltage Vdc. For example, when the DC bus voltage Vdc decreases and an abnormality is detected, the voltage margin calculation unit 17 can substantially invalidate the operation of the current command value limiter 8 (8a) by changing the voltage utilization factor K to "1.0", thereby ensuring the motor output even when the DC bus voltage Vdc decreases. Furthermore, in the present embodiment, the voltage margin calculation unit 17 changes the voltage margin by providing a transition period so as to change the voltage margin smoothly. Therefore, the motor control device 1 (1a) of this embodiment can suppress the sudden change of the current limiting command value (the d-axis current command value Id** and the q-axis current command value Iq** after limitation) by smoothly changing the voltage utilization coefficient K, and can suppress the abnormal noise and vibration of the motor caused by the change of the voltage utilization coefficient K.

[0110] [Implementation Method 4] Next, an electric power steering device 100 according to a fourth embodiment will be described with reference to the drawings. Fig.10 This is a block diagram showing an example of an electric power steering device 100 according to the fourth embodiment.

[0111] like Fig.10 As shown, the electric power steering device 100 includes a motor 10, a steering wheel 101, a torque sensor 102, a steering shaft 103, a wheel 104, a rack and pinion 105, a gear 106, and a control device 107. In addition, the control device 107 includes the above-mentioned motor control device 1 (1a), an abnormality detection unit 108, and a vehicle speed information communicator 109.

[0112] The torque sensor 102 detects a steering torque of a driver (not shown). The wheel 104 is a wheel (for example, a front wheel) that is a steering target of a vehicle such as an automobile. In the electric power steering device 100, the steering torque applied by the driver to the steering wheel 101 passes through the torsion bar of the torque sensor 102 and the steering shaft 103, and is transmitted to the rack via the rack and pinion 105. Thus, the electric power steering device 100 steers the wheels 104. The vehicle speed information communicator 109 measures the vehicle speed and notifies the motor control device 1 (1a) of the vehicle speed via the network.

[0113] In addition, the motor 10 is driven by the motor control device 1 (1a) of the control device 107, and generates an assist force as an output. The assist force is transmitted to the steering shaft 103 via the gear 106, thereby reducing the steering torque applied by the driver when steering. The control device 107 calculates an assist command for adjusting the assist force based on the driver's steering torque and the vehicle speed detected by the torque sensor 102. For example, the control device 107 calculates the assist command as a value proportional to the driver's steering torque. In addition, the control device 107 sets the assist command as a torque command, which becomes a command value of the motor 10.

[0114] The abnormality detection unit 108 monitors abnormalities in the electric power steering device 100 (control of the electric motor 10 ), and when a functional failure is detected, outputs an abnormality signal to the electric motor control device 1 ( 1 a ) to start control processing at the time of abnormality.

[0115] In addition, when an abnormality is detected in the control of the motor 10, the voltage margin calculation unit 17 of the present embodiment changes the voltage margin according to the detected abnormality. For example, when receiving an abnormality signal output by the abnormality detection unit 108, the voltage margin calculation unit 17 changes the voltage utilization coefficient K to "1.0".

[0116] In addition, the voltage margin calculation unit 17 in the present embodiment changes the voltage margin according to the speed of the vehicle on which the motor control device 1 (1a) is mounted. For example, when the vehicle speed received by the vehicle speed information communicator 109 exceeds a predetermined specific vehicle speed, the voltage margin calculation unit 17 changes the voltage utilization factor K to "1.0". In addition, for example, when the vehicle speed received by the vehicle speed information communicator 109 does not exceed a predetermined specific vehicle speed, the voltage margin calculation unit 17 changes the voltage utilization factor K to a specific value.

[0117] Next, we will refer to Fig.11 The operation of the electric power steering device 100 according to the present embodiment will be described.

[0118] exist Fig.11 In the following, an example of the operation of the voltage margin calculation unit 17 of the electric power steering device 100 will be described. Fig.11 Processing shown.

[0119] exist Fig.11 In the present embodiment, the voltage margin calculation unit 17 first determines whether an abnormal signal is detected (step S101). The voltage margin calculation unit 17 determines whether an abnormal signal is detected based on whether an abnormal signal output from the abnormality detection unit 108 is received. When an abnormal signal is detected (step S101: Yes), the voltage margin calculation unit 17 advances the process to step S103. In addition, when no abnormal signal is detected (step S101: No), the voltage margin calculation unit 17 advances the process to step S102. In step S102, the voltage margin calculation unit 17 determines whether the vehicle speed exceeds a specific vehicle speed. The voltage margin calculation unit 17 determines, for example, whether the vehicle speed received from the vehicle speed information communicator 109 exceeds the specific vehicle speed. When the vehicle speed exceeds the specific vehicle speed (step S102: Yes), the voltage margin calculation unit 17 advances the process to step S103. In addition, when the vehicle speed is below the specific vehicle speed (step S102: No), the voltage margin calculation unit 17 advances the process to step S104.

[0121] In step S103, the voltage margin calculation unit 17 changes the voltage utilization coefficient K to "1.0" (K=1.0). After the process of step S103, the voltage margin calculation unit 17 ends the process.

[0122] In step S104 , the voltage margin calculation unit 17 changes the voltage utilization coefficient K to a specific value (K=specific value). After the process of step S104 , the voltage margin calculation unit 17 ends the process.

[0123] As described above, the electric power steering device 100 of the present embodiment includes the above-mentioned motor control device 1 (1a), the motor 10 and the torque sensor 102. The motor 10 assists the steering of the steering gear. The torque sensor 102 detects the steering torque of the steering gear. The motor control device 1 (1a) controls the motor 10 by using the assist command of the steering gear corresponding to the steering torque detected by the torque sensor 102 as the command value of the motor 10.

[0124] Thus, the electric power steering device 100 of this embodiment has the same effect as the motor control device 1 (1a), and can suppress abnormal noise and vibration of the motor caused by voltage disturbance even when some voltage disturbance occurs at an operating point near the limited current command value.

[0125] In addition, when an abnormality is detected in the control of the motor 10, the voltage margin calculation unit 17 of the present embodiment changes the voltage margin (voltage utilization coefficient K) according to the detected abnormality. For example, when an abnormality is detected, the voltage margin calculation unit 17 changes the voltage margin by changing the voltage utilization coefficient K to "1.0".

[0126] Thus, the electric power steering device 100 (motor control device 1 (1a)) of the present embodiment can appropriately respond when an abnormality occurs in the control of the motor 10. For example, when the electric power steering device 100 (motor control device 1 (1a)) detects an abnormality, in order to continue to output the assist torque corresponding to the steering torque as much as possible, the voltage utilization coefficient K can be changed to "1.0", thereby invalidating the current command value limitation. Thus, the electric power steering device 100 of the present embodiment can suppress the reduction of the motor output caused by a certain functional failure, and can ensure the motor output even when an abnormality occurs.

[0127] In addition, the voltage margin calculation unit 17 in the present embodiment changes the voltage margin according to the speed of the vehicle on which the motor control device 1 (1a) is mounted. For example, when the vehicle speed exceeds a specific vehicle speed, the voltage margin calculation unit 17 changes the voltage margin by changing the voltage utilization coefficient K to "1.0". In addition, for example, when the vehicle speed is below a specific vehicle speed, the voltage margin calculation unit 17 changes the voltage utilization coefficient K to a specific value (a value less than 1.0) to change the voltage margin.

[0128] Thus, the electric power steering device 100 (motor control device 1 (1a)) of the present embodiment can ensure voltage margin by changing the voltage utilization factor K, thereby suppressing abnormal noise and vibration of the motor 10. For example, in the electric power steering device 100 (motor control device 1 (1a)) of the present embodiment, when the vehicle is traveling at high speed, that is, when the vehicle speed is high, in order to make an emergency avoidance, the voltage margin can be eliminated by changing the voltage utilization factor K, so that the motor output can be maximized, thereby ensuring the motor output.

[0129] In addition, the present disclosure is not limited to the above-mentioned embodiments, and can be modified within the scope not departing from the gist of the present disclosure. Each of the above-mentioned embodiments may be implemented independently, or a part of or each of the above-mentioned embodiments may be implemented in combination.

[0130] Although examples of using the integrator 84 are described in the above-mentioned embodiments, the present invention is not limited to this, and a proportional operator, a differential operator, etc. may be used instead of the integrator 84, or at least one of the proportional operator, the integrator and the differential operator may be used for operations.

[0131] In the above-mentioned third embodiment, an example using the abnormality of the DC bus voltage Vdc has been described in this embodiment, but this embodiment is not limited to this, and the voltage utilization coefficient K may be changed according to a parameter used in the motor control.

[0132] In the above-mentioned fourth embodiment, an example of changing the voltage utilization factor K based on the abnormal signal and the vehicle speed is described, but the present invention is not limited thereto. The voltage utilization factor K can be changed based on a signal used in other electric power steering, that is, the steering state of the driver, such as the steering torque Ts, the steering speed calculated from the rotation speed of the motor 10, etc. In addition, as an example of the driving state, the state of stopping and driving is used, but other driving states, such as the yaw rate indicating the turning state, the lateral acceleration signal, etc., can also be used.

[0133] In addition, each structure of the motor control device 1 (1a) includes a computer system inside. Moreover, a program for realizing the functions of each structure of the motor control device 1 (1a) can be recorded in a computer-readable recording medium, and the processing in each structure of the motor control device 1 (1a) can be performed by reading the program recorded in the recording medium into the computer system and executing the program. Here, "reading the program recorded in the recording medium into the computer system and executing it" includes installing a program in the computer system. The "computer system" mentioned here includes hardware such as OS and peripheral devices. In addition, the "computer system" may include a plurality of computer devices connected via a network including a communication line such as the Internet, WAN, LAN, and a dedicated line. In addition, the "computer-readable recording medium" refers to a portable medium such as a floppy disk, a magneto-optical disk, a ROM, a CD-ROM, and a storage device such as a hard disk built into the computer system. In this way, the recording medium storing the program may also be a non-temporary recording medium such as a CD-ROM.

[0134] In addition, the recording medium also includes an internal or external recording medium that can be accessed from a distribution server to distribute the program. In addition, the program may be divided into multiple parts, and after the program is downloaded at different time intervals, the structures incorporated in the various structures of the motor control device 1 (1a) may be different, or the distribution servers used to distribute the divided programs may be different. In addition, the so-called "computer-readable recording medium" also includes a medium that keeps the program for a certain period of time, such as a volatile memory (RAM) inside a computer system that becomes a server or client when sending a program via a network. In addition, the above-mentioned program may also be a program for realizing a part of the above-mentioned functions. And, it may also be a so-called differential file (differential program) that can realize the above-mentioned functions by combining with a program already recorded in the computer system. Description of symbols 1, 1a motor control device, 2 motor position detector, 3 DC power supply, 5 inverter, 6 DC bus voltage detection unit, 7 current command value calculation unit, 8, 8a current command value limiter, 9 speed calculator, 10 motor, 11 three-phase / two-phase coordinate converter, 12, 12a controller, 13 current detector, 14 two-phase / three-phase converter, 15, 15a correction voltage generator, 16 PWM signal generator, 17 voltage margin calculator, 41, 42, 43 shunt resistor, 51, 52, 53, 54, 55, 56 switching element, 81, 81a dq axis voltage operator, 82 limit voltage operator, 83, 85, 86, 121, 123 subtractor, 84 integral operator, 87, 88 current command value limiter, 100 electric power steering device, 101 steering wheel, 102 torque sensor, 103 steering shaft, 104 wheel, 105 rack and pinion, 106 gear, 107 control device, 108 abnormality detection unit, 109 vehicle speed information communicator, 110 motor control unit, 122 d axis controller, 124 q axis controller, 841, 845 amplifier, 842, 846 adder, 843, 847 current limiter, 844, 848 delay element.

Claims

1. A motor control device for controlling the energization of a motor by vector control, the motor control device comprising: a current command value calculation unit that generates a current command value in a dq coordinate system based on a command value of the motor; a current command value limiting unit that limits the current command value of the dq coordinate system generated by the current command value calculation unit and outputs the current command value of the dq coordinate system after the limit, that is, the current limit command value; as well as a controller that calculates a voltage command value for the motor by feedback control of the current limit command value, The current command value limiting unit limits the current command value of the dq coordinate system based on the DC bus voltage and the voltage command value so that an operating point has a set voltage margin with respect to a voltage limit circle of the dq coordinate system.

2. The motor control device according to claim 1, characterized in that: comprising a DC bus voltage detection unit, the DC bus voltage detection unit detecting the DC bus voltage, The current command value of the dq coordinate system includes a d-axis current command value and a q-axis current command value. The current command value limiting unit limits at least one of the d-axis current command value and the q-axis current command value based on the DC bus voltage detected by the DC bus voltage detecting unit and the voltage command value so that the operating point has the voltage margin with respect to the voltage limit circle.

3. The motor control device according to claim 2, characterized in that: The controller outputs a voltage command value of a dq coordinate system as the voltage command value, The current command value limiting unit limits at least one of the d-axis current command value and the q-axis current command value according to a deviation between a calculated value calculated based on the DC bus voltage and a value representing the voltage margin and a magnitude of a voltage vector represented by a voltage command value in the dq coordinate system.

4. The motor control device according to claim 2, characterized in that: The controller outputs a phase voltage command value corresponding to each of three phases of the motor as the voltage command value. The current command value limiting unit limits at least one of the d-axis current command value and the q-axis current command value according to a deviation between a magnitude of a composite voltage vector of the phase-to-phase voltages calculated based on the DC bus voltage and a value representing the voltage margin and based on the phase voltage command values ​​corresponding to the phases.

5. The motor control device according to claim 3 or 4, characterized in that: The current command value limiting unit limits at least one of the d-axis current command value and the q-axis current command value according to an integrated value of the deviation.

6. The motor control device according to any one of claims 1 to 5, characterized in that: comprising a voltage margin setting unit configured to variably set the voltage margin, The current command value limiting unit limits a current command value of the dq coordinate system based on the voltage margin set by the voltage margin setting unit.

7. The motor control device according to claim 6, characterized in that: The voltage margin setting unit changes the voltage margin by providing a transition period so that the voltage margin changes smoothly.

8. The motor control device according to claim 6 or 7, characterized in that: When an abnormality is detected in the control of the electric motor, the voltage margin setting unit changes the voltage margin according to the detected abnormality.

9. The motor control device according to any one of claims 6 to 8, characterized in that: The voltage margin setting unit changes the voltage margin according to a speed of a vehicle on which the motor control device is mounted.

10. The motor control device according to any one of claims 1 to 9, characterized in that: The voltage margin is set based on the DC bus voltage.

11. An electric power steering device, characterized in that: include: The motor control device according to any one of claims 1 to 10; The electric motor is used to assist the steering of the steering gear; as well as a torque sensor for detecting a steering torque of the steering gear, The motor control device controls the motor by using an assist command of the steering gear corresponding to the steering torque detected by the torque sensor as a command value of the motor.

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