AC motor control device, electric vehicle, and AC motor control method

Abstract

Provided is an AC motor control device for driving and controlling an AC motor by means of voltage phase control, the AC motor control device being capable of suppressing the reverse response of a current and enabling the overall response to be at a high speed. The AC motor control device converts direct current into alternating current on the basis of a voltage phase command output from a voltage phase control unit and outputs the alternating current to an AC motor, and is characterized in that the voltage phase control unit includes a change amount limiting unit that limits the amount of change in the voltage phase.

Description

Technical Field

[0001] The present invention relates to a structure of an AC motor control device for driving and controlling an AC motor and a control method thereof, and in particular to an effective technology applicable to an AC motor for an electric vehicle requiring both high responsiveness and vibration suppression. Background Art

[0002] The drive system of electric vehicles such as EVs (Electric Vehicles) requires lightweight, compact, and low-cost, as well as low noise and vibration. In particular, when rotating at high speeds, there are technical problems such as significant vibration and energy loss of the motor, and various technologies are being developed to suppress the vibration of the motor during high-speed rotation.

[0003] On the other hand, in the control of AC motors based on voltage phase control (rectangular wave drive, etc.), application of pulse-saving control (for example, 1-pulse control) is being studied in order to improve voltage utilization in a high-speed region.

[0004] As background technology in this technical field, there is a technology such as Patent Document 1. In Patent Document 1, in order to achieve a voltage close to the output voltage limit of the inverter, a voltage phase control is proposed to control the voltage phase angle in a manner that the torque is consistent with the command value. In this control, in order to prevent the voltage phase angle from reaching outside the specified range and causing control failure, a limiter is given to the voltage phase angle.

[0005] Furthermore, Patent Document 2 proposes a control for suppressing the d-axis current value from deviating from a normal control range by performing an annealing process on the calculation of the torque estimation value. Prior art literature Patent Literature

[0006] Patent Document 1: Japanese Patent No. 3746377 Patent Document 2: Japanese Patent Application Publication No. 2010-183661 Summary of the invention Technical problem to be solved by the invention

[0007] However, in the voltage phase control of the AC motor to which the above-mentioned pulse saving control (e.g., 1-pulse control) is applied, when the response is accelerated, there is a case where the response is too fast and the current reverses. Since this reverse response may cause vibration of the AC motor, it is necessary to limit the response as a whole so as not to make a reverse response.

[0008] However, if the response is limited overall, the response becomes too slow.

[0009] Figure 1 This shows an example of the reverse response of the current in voltage phase control. Figure 1 , the response of the actual current value 63 to the input of the current command value 61 is shown.

[0010] In voltage phase control, if the response is accelerated, Figure 1 As shown, there are cases where the current responds in the direction opposite to the change in the command value and then follows the reverse response characteristic of the command value.

[0011] Such a reverse response cannot be suppressed even if a voltage phase angle is limited by the voltage phase control of Patent Document 1.

[0012] In addition, in Patent Document 2, the d-axis current can be suppressed when it performs reverse response, but it does not assume that the q-axis current performs reverse response. The situation where reverse response occurs is particularly problematic when the reverse response occurs at the maximum current and becomes an overcurrent, and when the d-axis current becomes a current in the positive direction from the negative direction that is the normal range under reverse response. Patent Document 2 is a countermeasure for the latter and does not work for the former.

[0013] As described above, the conventional technology does not envision the situation where the q-axis current performs a reverse response and becomes an overcurrent.

[0014] Therefore, an object of the present invention is to provide an AC motor control device and an AC motor control method, in which, in an AC motor control device for driving and controlling an AC motor by voltage phase control, the reverse response of the current can be suppressed and the response speed can be increased as a whole. Technical solutions to technical problems

[0015] In order to solve the above technical problems, the present invention is an AC motor control device, which converts DC power into AC power based on a voltage phase instruction output from a voltage phase control unit, and outputs the AC power to the AC motor, characterized in that the voltage phase control unit includes a change amount limiting unit that imposes a limit on the change amount of the voltage phase.

[0016] Furthermore, the present invention is an AC motor control method for controlling the driving of the AC motor, characterized in that a limit is imposed on a change amount of a voltage phase command output from a voltage phase control unit. Effects of the Invention

[0017] According to the present invention, an AC motor control device and an AC motor control method can be realized, in which the reverse response of the current can be suppressed and the response can be accelerated as a whole in the AC motor control device that drives and controls the AC motor by voltage phase control.

[0018] This can contribute to vibration suppression and improvement of riding comfort in high-speed areas of electric vehicles such as EVs.

[0019] Technical problems, structures, and effects other than those described above will become more apparent through the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a diagram schematically showing an example of the reverse response of the current in the voltage phase control. Figure 2 This is a block diagram showing the overall configuration of an AC motor control device according to the first embodiment of the present invention. Figure 3 Yes means Figure 2 A block diagram of an example of a rectangular wave generating unit 15. Figure 4 Yes means Figure 2 A block diagram of an example of a voltage phase control unit 13 is shown. Figure 5 FIG. 2 is a diagram schematically showing the movement trajectory of the current based on the stability term. Figure 6 This is a diagram showing an example of a situation in which a reverse response of the current occurs during forward rotation. Figure 7 This is a diagram showing an example of a situation in which a reverse response of a current is generated during inversion. Figure 8 This is a block diagram showing the overall configuration of an AC motor control device according to a second embodiment of the present invention. Fig. 9 Yes means Figure 8 A block diagram of an example of a voltage phase control unit 13B. Fig.10 Yes means Fig. 9 FIG. 4 is a diagram showing an example of a correspondence table between input and output of the limit value calculation unit 49. Fig.11 2 is a diagram showing a modified example of the correspondence table between the input and output of the limit value calculation unit 49 . Fig.12 2 is a diagram showing a modified example of the correspondence table between the input and output of the limit value calculation unit 49 . Fig.13 2 is a diagram showing a modified example of the correspondence table between the input and output of the limit value calculation unit 49 . Fig.14 This is a diagram showing a schematic structure of an electric vehicle according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0021] Hereinafter, the embodiments of the present invention will be described using the drawings. In addition, in each of the drawings, the same reference numerals are given to the same structures, and the detailed description of the repeated parts is omitted.

[0022] In the following description, a permanent magnet synchronous motor (PMSM) is used as the object, but the present invention is not limited to the permanent magnet synchronous motor, and the same effect can be obtained if it is a synchronous motor such as a synchronous reluctance motor, a permanent magnet synchronous generator, and a winding type synchronous motor.

[0023] Furthermore, the semiconductor switching element of the inverter device is assumed to be an IGBT (Insulated Gate Bipolar Transistor), but the present invention is not limited thereto, and may be a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) or other power semiconductor element. Example 1

[0024] Reference Figures 2 to 7 , the AC motor control device involved in Example 1 of the present invention is described.

[0025] Figure 2 1 is a block diagram showing the overall configuration of an AC motor control device 10 according to the present embodiment. Figure 3 Yes means Figure 2 A block diagram of an example of a rectangular wave generating unit 15, Figure 4 Yes means Figure 2 A block diagram of an example of a voltage phase control unit 13 is shown. Figure 5 FIG. 2 is a diagram schematically showing the movement trajectory of the current based on the stability term. Figure 6 1 is a diagram showing an example of a situation in which a reverse response of a current is generated during forward rotation. Figure 7 This is a diagram showing an example of the reverse response of the current when the inversion occurs.

[0026] like Figure 2 As shown, the AC motor control device 10 of this embodiment has a power converter 2, a phase current detection unit 3, a magnetic pole position detector 4, a frequency calculation unit 5, a coordinate conversion unit 7, a torque calculation unit 11, a voltage phase control unit 13, and a rectangular wave generation unit 15 as main structures.

[0027] The power converter 2 converts direct current from a direct current voltage source 9 (eg, a battery) into alternating current according to a gate signal (eg, a rectangular wave pulse signal) described later, to drive a permanent magnet synchronous motor (PMSM) 1 .

[0028] The phase current detection unit 3 is composed of a Hall CT (Current Transformer) or the like, and detects current waveforms Iuc, Ivc, and Iwc of three phases, namely, U-phase, V-phase, and W-phase, flowing from the power converter 2 to the PMSM 1 .

[0029] The magnetic pole position detector 4 is constituted by a resolver or the like, detects the magnetic pole position of the PMSM 1 , and outputs magnetic pole position information θ*.

[0030] The frequency calculation unit 5 outputs speed information ω1* by, for example, differential calculation based on the magnetic pole position information θ* detected by the magnetic pole position detector 4 .

[0031] The coordinate conversion unit 7 performs coordinate conversion on Iuc, Ivc, and Iwc detected by the phase current detection unit 3 using the magnetic pole position information θ* detected by the magnetic pole position detector 4 , and outputs dq axis current detection values ​​Idc and Iqc.

[0032] The torque calculation unit 11 uses the dq axis current detection values ​​Idc and Iqc to calculate the torque T. The torque calculation unit 11 performs the calculation using, for example, equation (1).

[0033] [Mathematical formula 1] T=N((L d -L q )I dc +φ m )I qc …(1)

[0034] Here, Ld and Lq represent dq-axis inductances, respectively, φm represents the magnetic flux coefficient, and N represents the number of pole pairs.

[0035] Alternatively, calculations may be performed using a lookup table instead of a mathematical expression.

[0036] The voltage phase control unit 13 outputs a voltage phase angle θv so that the torque T matches the torque command value T*. This function is a function that is the essence of the invention and will be described in detail later.

[0037] The rectangular wave generating unit 15 is, for example, Figure 3 As shown, the voltage phase angle θv and π / 2 are added to the magnetic pole position information θ* by an adder 81 to generate a voltage phase signal, and the remainder obtained by dividing by 2π is calculated by a remainder operation unit 87. Then, π is subtracted by a subtractor 93, and the sign (positive or negative) of the output of the subtractor 93 is determined by a sign determiner 96, and the pulse signal Su is calculated based on the sign.

[0038] Similarly, 4π / 3 and 2π / 3 are added to the voltage phase signal by adders 83 and 85, respectively, and remainders obtained by dividing by 2π are calculated by remainder calculation units 89 and 91, respectively, and then π is subtracted by subtractors 94 and 95, respectively, and signs (positive and negative) are determined by sign determination units 97 and 98 for the outputs of subtractors 94 and 95, and pulse signals Sv and Sw are calculated based on the signs. Taking the dead time into consideration, gate signals are generated and output from pulse signals Su, Sv, and Sw.

[0039] Next, the voltage phase control unit 13, which is the inventive point of the present invention, will be described in detail.

[0040] Figure 4 An example of the voltage phase control unit 13 is shown.

[0041] The difference between the torque command value T* and the torque T is calculated by a subtractor 51, and the gain taking the response into consideration is multiplied by a gain 53, and the change amount Δθv of the voltage phase angle is output to a limiter 55. On the other hand, a limit value Δθlim obtained by multiplying the speed information ω1* calculated by the frequency calculation unit 5 by a gain 52 is output to the limiter 55.

[0042] The limiter 55 limits the output so that the change amount Δθv of the voltage phase angle is within the range of ±Δθlim.

[0043] The integrator 57 integrates the amount of change Δθv of the voltage phase angle limited by the limiter 55 and outputs the integrated amount to the limiter 59 .

[0044] The limiter 59 limits the output voltage phase angle θv so as not to enter the unstable region.

[0045] Next, the principle of voltage phase control by the voltage phase control unit 13 will be described.

[0046] dq axis voltage δv d ,δv q The voltage phase operation amount δθ v The response is formula (2).

[0047] [Mathematical formula 2]

[0048] dq axis current δi d ,δi q For dq axis voltage δv d ,δv q The response is formula (3).

[0049] [Mathematical formula 3]

[0050] According to equations (2) and (3), the dq axis current δi d ,δi q The voltage phase operation amount δθ v The response is given by equation (4). However, since R<<Lqω1, the resistance R is ignored.

[0051] [Formula 4]

[0052] According to the stability term shown in equation (5) with s=0 in equation (4), the current 32 follows Figure 5 The constant pressure ellipse 31 shown moves, and according to the transition term shown in equation (6), it moves away from the constant pressure ellipse 31.

[0053] [Formula 5]

[0054] [Mathematical formula 6]

[0055] Here, we focus on the transition term that acts in a direction that deviates from the assumed operation, and when the current is substituted for the voltage, we obtain equation (7).

[0056] [Formula 7]

[0057] According to the formula of Id, since φm and Ld are positive, Id is near 0, and the d-axis current responds in the positive direction when Δθv (= s×θv) is positive in the forward rotation (ω1>0), that is, when rotating in the direction of torque reduction. When Id increases in the negative direction, Id0+φm / Ld decreases, so due to the change in the voltage phase angle Δθv (= s×θv), the effect of the d-axis current acting in the direction of departure from the constant pressure ellipse 31 becomes smaller.

[0058] On the other hand, according to the formula of Iq, when Δθv (= s × θv) is positive in the forward rotation (ω1>0), that is, when the rotation is in the direction of torque reduction, it acts in the direction of Iq increase. In this case, when Iq is positive, overcurrent may be generated. On the other hand, when Δθv (= s × θv) is negative in the forward rotation (ω1>0), that is, when the rotation is in the direction of torque increase, it acts in the direction of Iq decrease. In this case, when Iq is negative, overcurrent may be generated.

[0059] In summary, if Figure 6 shown. Figure 6 This is a diagram showing an example of the reverse response of the current during forward rotation. In the diagram, "step" indicates when the torque command changes (especially when the change is in a step shape), and "zero crossing" indicates when the torque passes through 0. Figure 6 As shown, a total of 6 modes are considered as the case where the reverse response occurs largely.

[0060] Figure 7 This is the result of the same study in the reverse rotation (ω1<0). Regarding Iq, since ΔIq is generated in the direction of torque change, it will not be a reverse response. Regarding Id, in contrast to the forward rotation, when rotating in the direction of increasing torque (when Δθv is negative), a reverse response may occur.

[0061] Here, it can be seen that in order to suppress the reverse response, it is sufficient to limit the change amount Δθv of the voltage phase angle. In addition, since the amount of reverse response is inversely proportional to the speed ω1, the limit value Δθlim of the change amount Δθv of the voltage phase angle can be determined in proportion to the speed ω1.

[0062] Furthermore, the gain to be multiplied by the gain 52 is determined based on the equation (7). Assuming that the change amount limit value of the d-axis current is ΔId_lim, the change amount Δθv of the voltage phase angle when Id=0 is represented by the equation (8).

[0063] [Mathematical formula 8]

[0064] On the other hand, assuming that the change amount limit value of the q-axis current is ΔIq_lim, the change amount Δθv of the voltage phase angle limit value Δθlim is expressed by equation (9).

[0065] [Mathematical formula 9]

[0066] Iq0 may use the current Iq or may be calculated based on the q-axis current at the time of maximum torque. Alternatively, a value obtained by adding a filter that takes response into consideration to the q-axis current command value may be used.

[0067] In the above equations (8) and (9), if the smaller value is used as the gain used in the calculation of Δθlim, it can be suppressed within the change amount limit values ​​ΔId_lim and ΔIq_lim assuming the reverse response.

[0068] As described above, the AC motor control device 10 of this embodiment is an AC motor control device that converts DC power into AC power and outputs the AC power to PMSM1 based on the voltage phase command output from the voltage phase control unit 13, and the voltage phase control unit 13 has a change amount limiting unit that imposes limits on the change amount of the voltage phase command.

[0069] Then, the variation limiting unit performs control so that the variation of the voltage phase command falls within a predetermined range.

[0070] Furthermore, the variation limiting unit changes the limitation amount of the variation amount of the voltage phase command in proportion to the rotation speed ω1 of the PMSM 1 .

[0071] Furthermore, the variation limiting unit determines whether to impose a restriction on the variation of the voltage phase command based on the current command value or the current detection value detected by the phase current detection unit 3 , and changes the restriction amount of the variation.

[0072] Furthermore, the variation limiting unit determines whether or not to limit the variation of the voltage phase command based on the rotation direction of the PMSM 1 , and changes the limit amount of the variation.

[0073] The gain multiplied by the gain 52 may not be determined by a mathematical formula but may be adjusted based on a step response through an actual device test or simulation.

[0074] In this embodiment, the limit value Δθlim of the voltage phase angle change Δθv is set so that the d-axis current does not reach the positive region due to the reverse response and the q-axis current does not become an overcurrent due to the reverse response, but it can also be used to suppress either event.

[0075] In addition, in the present embodiment, an example of a method of operating the voltage phase angle θv to make the torque T consistent with the torque command value T* is shown, but the present invention can also be applied if the voltage phase angle θv is operated such as operating the voltage phase angle θv to make the q-axis current consistent with the q-axis current command value or operating the voltage phase angle θv to make the d-axis current consistent with the d-axis current command value.

[0076] In the present embodiment, an example of one-pulse control is shown as pulse-saving control, but the present invention can be applied even to three-pulse control or the like as long as a torque control method for operating the voltage phase angle θv is adopted. Example 2

[0077] Reference Figures 8 to 13 , an AC motor control device according to a second embodiment of the present invention is described.

[0078] Figure 8 1 is a block diagram showing the overall configuration of the AC motor control device 20 according to the present embodiment. Fig. 9 Yes means Figure 8 A block diagram of an example of a voltage phase control unit 13B. Fig.10 Yes means Fig. 9 FIG. 4 is a diagram showing an example of a correspondence table between input and output of the limit value calculation unit 49. Figures 11 to 13 Each of them is a diagram showing an example of a correspondence table of the relationship between input and output of the limit value calculation unit 49 .

[0079] In this embodiment, the description will focus on the differences in structure from the first embodiment.

[0080] like Figure 8 As shown, the AC motor control device 20 of this embodiment is different from that of the embodiment 1 ( Figure 2 ) is different from the AC motor control device 10 in that the dq axis current detection values ​​Idc and Iqc from the coordinate conversion unit 7 are added as inputs to the voltage phase control unit 13B.

[0081] Fig. 9 The detailed structure of the voltage phase control unit 13B is shown.

[0082] In the limit value calculation unit 49, according to Fig.10 The condition table calculates the voltage phase change limit +Δθlim in the positive direction and the voltage phase change limit -Δθlim in the negative direction based on the dq axis current detection values ​​Idc, Iqc and the speed information ω1*.

[0083] Fig.10 based on Figure 6 , Figure 7 As well as equations (8) and (9), the voltage phase change limit value that can suppress the reverse response is shown according to the rotation direction and current conditions.

[0084] Idset is set to 0, for example, and voltage phase change amount limits +Δθlim and -Δθlim are set to suppress the d-axis current Idc from making a reverse response to the positive region when it is greater than Idset.

[0085] In addition, Iqset is set to, for example, 90% of the maximum value of the q-axis current Iqc, and voltage phase change limits +Δθlim and -Δθlim are set to suppress the occurrence of reverse response and overcurrent when it is greater than Iqset.

[0086] Thus, the reverse response can be suppressed by limiting the change amount Δθv of the voltage phase angle only when a reverse response occurs, and the response can be accelerated by not limiting the change amount Δθv of the voltage phase angle in other regions.

[0087] In this embodiment, although the conditions are changed by forward rotation and reverse rotation, when only the motor for forward rotation is basically used, in order to simplify the software, for example, Fig.11 In the condition table shown, the voltage phase change amount limits +Δθlim and -Δθlim are calculated, and the reverse rotation condition is ignored, so the judgment can be made only by the forward rotation.

[0088] In addition, Fig.10In the example, the voltage phase change limit +Δθlim and -Δθlim are changed in the positive and negative directions, but in order to simplify the software, for example, according to Fig.12 In the condition table shown, voltage phase change amount limits +Δθlim and -Δθlim are calculated, and the voltage phase change amount limit value, which is the stricter limit condition, is set in both positive and negative directions.

[0089] Alternatively, in equations (8) and (9), equation (10) represents the ratio of the change limit value ΔId_lim to the d-axis current required to weaken the magnetic flux, and equation (11) represents the ratio of the change limit value ΔIq_lim to the current current. Therefore, for example, according to Fig.13 In the condition table shown, the voltage phase change amount limits +Δθlim and -Δθlim are calculated, and the constant K can be set to, for example, 10% (0.1).

[0090] [Formula 10]

[0091] [Mathematical formula 11]

[0092] In addition, in the present embodiment, the dq axis currents Idc and Iqc are used, but values ​​that take into account the delay of the current control may be used as the dq axis current command values.

[0093] In the present embodiment, the q-axis current Iqc is used for determination. However, instead of using the q-axis current Iqc for determination, determination may be made t seconds after a step response of a change ΔT* in the torque command value is added to the torque command value T*.

[0094] Alternatively, it may be determined that it is not the torque command value T* but t seconds after the step response of the q-axis current command value Iq* is added.

[0095] Alternatively, it may be determined that the q-axis current Iqc changes by the amount ΔIq from the time the step response is added until the time when the q-axis current Iqc changes in the direction of the step response.

[0096] In addition, in the present embodiment, the current is used to determine the situation in which the reverse response occurs, but the magnetic flux proportional to the current may be used instead of the current.

[0097] As described above, as long as it can represent the Figure 6 , Figure 7With such judgment conditions for the condition that produces a reverse response of the current, no matter which method is used, it is possible to judge that the condition can produce a reverse response, and the reverse response can be suppressed by setting a limit on the change in the voltage phase angle Δθv. In addition, the limit on the change in the voltage phase angle Δθv can be removed outside the condition that can produce a reverse response, thereby speeding up the response.

[0098] In addition, in the present embodiment, an example of a method of operating the voltage phase angle θv to make the torque T consistent with the torque command value T* is shown, but the present invention can be applied if the voltage phase angle θv is operated such as operating the voltage phase angle θv to make the q-axis current consistent with the q-axis current command value or operating the voltage phase angle θv to make the d-axis current consistent with the d-axis current command value.

[0099] In the present embodiment, an example of one-pulse control is shown as pulse-saving control, but the present invention can be applied even to three-pulse control or the like as long as a torque control method for operating the voltage phase angle θv is adopted. Example 3

[0100] Reference Fig.14 , describing the electric vehicle involved in Example 3 of the present invention.

[0101] Fig.14 1 is a diagram showing a schematic configuration of an electric vehicle according to this embodiment. The electric vehicle according to this embodiment uses the AC motor control device described in the first or second embodiment as a motor control device 300 .

[0102] As described in the first and second embodiments, the motor control device 300 controls the power supplied from the power converter (inverter) 2 to the permanent magnet synchronous motor (PMSM) 1 .

[0103] A DC voltage source (eg a battery) 9 supplies power to the inverter 2 .

[0104] The PMSM 1 is connected to the transmission 301 .

[0105] Transmission 301 is connected to drive shaft 305 via differential gear 303, and supplies power to wheels 307. Alternatively, transmission 301 may be omitted and directly connected to differential gear 303, or PMSM 1 and inverter 2 may be applied to the front and rear wheels, respectively.

[0106] In automotive motors, high-speed torque response is required to suppress vibration and control idling, so high-speed response in voltage phase control is required compared to other applications. In addition, due to miniaturization, the margin for overcurrent is small, so reverse response needs to be suppressed.

[0107] Therefore, it can be said that the effect of the present invention is significantly manifested in the application. Similarly, railway vehicles are also mobile bodies like automobiles, and since idling control is required, they are also applications where the effect of the present invention is easily manifested. By applying the present invention, the reverse response can be suppressed in automobiles and railway vehicles, so the response can be improved as a whole. As a result, the riding comfort of the driver or passengers can be improved.

[0108] The present invention is not limited to the above-mentioned embodiments, but also includes various modified examples. For example, the above-mentioned embodiments are detailed descriptions for the purpose of facilitating the understanding of the present invention, and are not limited to all structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of other embodiments, and the structure of other embodiments can also be added to the structure of a certain embodiment. In addition, with respect to a part of the structure of each embodiment, other structures can also be added, deleted, or replaced. Description of symbols

[0109] 1Permanent Magnet Synchronous Motor (PMSM) 2 Power converter (inverter) 3-phase current detection unit 4-pole magnetic position detector 5Frequency calculation unit 7Coordinate conversion unit 9 DC voltage source (battery) 10, 20 AC motor control device 11Torque calculation unit 13. 13B Voltage phase control unit 15 Rectangular wave generating unit 31 Constant Pressure Ellipse 32 Current 49 Limit value calculation unit 51, 93, 94, 95 subtractors 52, 53 gain 55, 55A, 59 limiters 57 Integrator 61 Current command value 63 Actual current value 81, 83, 85 adders 87, 89, 91 remainder operation unit 96, 97, 98 symbol determiner 300 Motor Control Device 301 Transmission 303 Differential gear 305 Drive shaft 307 wheels.

Claims

1. An AC motor control device, which converts DC power into AC power based on a voltage phase command output from a voltage phase control unit and outputs the AC power to an AC motor, characterized in that: The voltage phase control unit includes a change amount limiting unit that limits the change amount of the voltage phase.

2. The AC motor control device according to claim 1, characterized in that: The variation limiting unit performs control so that the variation of the voltage phase falls within a predetermined range.

3. The AC motor control device according to claim 1, characterized in that: The variation limiting unit changes the limitation amount of the variation of the voltage phase in proportion to the rotation speed of the AC motor.

4. The AC motor control device according to claim 1, characterized in that: comprising a current detection unit, the current detection unit detecting the current of the AC motor, The change amount limiting unit determines whether to impose a limit on the change amount of the voltage phase based on a current command value or a current detection value detected by the current detection unit, and changes a limit amount of the change amount.

5. The AC motor control device according to claim 4, characterized in that: The variation limiting unit determines whether to impose a restriction on the variation of the voltage phase based on the rotation direction of the AC motor, and changes a restriction amount of the variation.

6. The AC motor control device according to claim 1, characterized in that: A power converter is provided for converting direct current into alternating current based on a voltage phase command output from the voltage phase control unit. The power converter uses rectangular wave pulses.

7. An electric vehicle, characterized in that: The device comprises the AC motor control device as claimed in any one of claims 1 to 6.

8. An AC motor control method, which controls the driving of the AC motor, characterized in that: A restriction is imposed on the amount of change of the voltage phase command output from the voltage phase control unit.

9. The AC motor control method according to claim 8, characterized in that: Control is performed so that the change amount of the voltage phase command falls within a prescribed range.

10. The AC motor control method according to claim 8, characterized in that: The limit amount of the change amount of the voltage phase command is changed in proportion to the rotation speed of the AC motor.

11. The AC motor control method according to claim 8, characterized in that: Based on the current command value or the current detection value of the AC motor, it is determined whether to impose a limit on the amount of change of the voltage phase command, and the limit amount of the amount of change is changed.

12. The AC motor control method according to claim 11, characterized in that: Based on the rotation direction of the AC motor, it is determined whether to impose a limit on the amount of change of the voltage phase command, and the limit amount of the amount of change is changed.

13. The AC motor control method according to claim 8, characterized in that: The direct current is converted into alternating current using rectangular wave pulses and supplied to the AC motor.

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