Actuating device and driving method thereof

Abstract

The present invention discloses an actuator and a driving method thereof, which comprises: an AC motor, the AC motor receiving a driving voltage; a driver; when the driver is in a first mode, the driver is used to set a first voltage margin as the set voltage margin according to the command signal; and to generate the set magnetic flux according to the mechanical command and the speed information of the AC motor; when the driver is in a second mode, the driver is used to set a second voltage margin as the set voltage margin according to the command signal, the first voltage margin being less than the second voltage margin; and to make the set magnetic flux equal to the rated magnetic flux. The switching of the control mode can be adjusted in real time in different processing environments, effectively improving performance, energy saving and stability.

Description

Technical Field

[0001] The present invention relates to an actuating device and a driving method thereof, and in particular to an actuating device and a driving method thereof which can improve performance and efficiency. Background Art

[0002] In the past, in the energy-saving control of induction motors, the operating points of the motors were mostly calculated in different ways, and there was no real-time adjustment of the control mode switching for different usage environments and during the processing process. Therefore, the applicable environment will be limited and may only be applicable to no-load or low-load environments. If there is a light load but high-precision environment during the entire operation process, it will not provide the best response due to the low operating flux. In addition, in the design of voltage margin, there has been no method for switching voltage margin during processing in the past, so in order to have good acceleration and deceleration performance, the voltage margin is usually set lower. If fine processing is required at this time, it will be easy to reach the upper limit of the voltage due to insufficient voltage margin, resulting in poor stability.

[0003] In the past, patents that used commands from a higher-level controller to control energy-saving functions were mostly applied to multiple workpiece processing or multiple processing steps. For example, some motors were originally kept in a standby state during certain processing steps, but a power-off command was inserted before the standby state began, and the motors were restarted before the processing was needed to save energy during the standby state. However, this method cannot save energy during the processing action. Summary of the invention

[0004] In view of this, an object of the present invention is to provide an actuator and a driving method thereof in order to overcome the deficiencies of the prior art, which can dynamically switch between different modes during processing while improving performance, energy saving and stability.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: an actuating device, which comprises:

[0006] an AC motor, the AC motor receiving a driving voltage;

[0007] a driver driving the AC motor, the driver switching between a first mode and a second mode according to a command signal, generating a torque command according to a force command, generating a current voltage command according to the torque command, a set magnetic flux, a set voltage margin and a previous voltage command, and generating the driving voltage according to the current voltage command;

[0008] When the driver is in the first mode, the driver is used to:

[0009] setting the first voltage margin as the set voltage margin according to the command signal; and,

[0010] generating the set magnetic flux according to the mechanical command and the speed information of the AC motor;

[0011] When the driver is in the second mode, the driver is used to:

[0012] setting a second voltage margin as the set voltage margin according to the command signal, the first voltage margin being smaller than the second voltage margin; and,

[0013] The set magnetic flux is made equal to the rated magnetic flux.

[0014] Optimally, the driver is used to generate speed error information according to the mechanical command and the speed information of the AC motor, and to generate the torque command according to the speed error information.

[0015] Optimally, the driver obtains the excitation axis current information according to the set voltage margin, the set flux and the previous voltage command, obtains the torque axis current information according to the torque command, and generates the current voltage command according to the excitation axis current information and the torque axis current information.

[0016] Optimally, the driver further comprises determining whether the driving voltage generated by the current voltage command is greater than a maximum driving voltage, and when the driving voltage is greater than the maximum driving voltage, making the driving voltage equal to the maximum driving voltage.

[0017] Optimally, corresponding to the same AC motor speed information, the power consumption of the actuator in the first mode is less than or equal to the power consumption in the second mode.

[0018] Optimally, the driver also operates in a third mode which is a general mode according to the command signal; corresponding to the same AC motor speed information, the power consumption of the actuator in the first mode is less than its power consumption in the third mode.

[0019] Another object of the present invention is to provide a driving method of the above-mentioned actuator for driving an AC motor, which comprises the following steps:

[0020] switching between a first mode and a second mode according to a command signal;

[0021] Generate torque command according to mechanical command;

[0022] generating a current voltage command according to the torque command, the set magnetic flux, the set voltage margin and the previous voltage command; and,

[0023] generating a driving voltage for driving the AC motor according to the current voltage command;

[0024] When the driver is in the first mode, the driver is used to:

[0025] setting the first voltage margin as the set voltage margin according to the command signal; and,

[0026] generating the set magnetic flux according to the mechanical command and the speed information of the AC motor;

[0027] When the driver is in the second mode, the driver is used to:

[0028] setting a second voltage margin as the set voltage margin according to the command signal, the first voltage margin being smaller than the second voltage margin; and,

[0029] The set magnetic flux is made equal to the rated magnetic flux.

[0030] Optimally, the step of generating a torque command according to a mechanical command comprises:

[0031] generating speed error information according to the mechanical command and the speed information of the AC motor; and,

[0032] The torque command is generated according to the rotation speed error information.

[0033] Optimally, the step of generating a current voltage command according to the torque command, setting the magnetic flux, setting the voltage margin and the previous voltage command comprises:

[0034] obtaining exciting shaft current information according to the set voltage margin, the set magnetic flux and the previous voltage command; and,

[0035] Torque shaft current information is obtained according to the torque command.

[0036] Optimally, it also includes the following steps:

[0037] Determining whether the driving voltage generated by the current voltage command is greater than a maximum driving voltage; and,

[0038] When the driving voltage is greater than the maximum driving voltage, the driving voltage is made equal to the maximum driving voltage.

[0039] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: the actuator proposed by the present invention can control the driver to switch between the first mode and the second mode according to the command signal by setting the AC motor and the driver, and matching the driving method, and then generate a torque command according to the mechanical command, so as to generate a current voltage command according to the torque command, the set magnetic flux, the set voltage margin and the previous voltage command, and generate a driving voltage according to the current voltage command to drive the AC motor. The switching of the control mode can be adjusted in real time in different processing environments, effectively improving performance, energy saving and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A system schematic diagram of an actuating device according to an embodiment of the present invention;

[0041] Figure 2 is an action flow chart of the actuating device according to an embodiment of the present invention;

[0042] Figure 3A This is a schematic diagram of the operation of the intelligent energy-saving mode according to an embodiment of the present invention;

[0043] Figure 3B It is a schematic diagram of the action of the fine-tuning mode according to an embodiment of the present invention;

[0044] Figure 4A is an action waveform diagram of an actuator according to an embodiment of the present invention;

[0045] Figure 4B is an action waveform diagram of an actuator according to an embodiment of the present invention;

[0046] Figure 5 FIG. 4 is a block diagram of a driving method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention will be described in detail below.

[0048] like Figure 1 As shown, Figure 1 FIG. 1 is a schematic diagram of a system of an actuating device according to an embodiment of the present invention. Figure 1 In the embodiment, the actuator 100 includes a driver 101 and an AC motor 102. In this embodiment, the actuator 100 can be coupled to an external host. The external host is used to control the actuator 100 to perform a processing control action. The AC motor 102 in this embodiment can be an induction motor.

[0049] In this embodiment, the external host can be a host controller or an external device with input and output functions, and there is no fixed restriction. The driver 101 can be an arithmetic unit with computing capabilities, such as a central processing unit (CPU) or other programmable general-purpose or special-purpose microprocessor (Microprocessor), digital signal processor (DSP), programmable controller, application specific integrated circuits (ASIC), programmable logic device (PLD) or other similar devices or combinations of these devices, which can load and execute computer programs to complete corresponding operating functions. In one embodiment, the driver can also implement various operating functions in a hardware circuit manner, and its detailed steps and implementation methods can be sufficiently taught, suggested and implemented by the general knowledge in the relevant technical field.

[0050] Regarding the operation of the actuator 100 of this embodiment, please also refer to Figure 1 as well as Figure 2 ,in Figure 2 The flowchart of the actuating device of the embodiment of the present invention is shown. In the embodiment, steps S210 and S220 can be executed by an external host, steps S230 to S250 are executed by the driver 110 , and step S260 is executed by the AC motor 102 .

[0051] In step S210 , the external host starts to execute the processing action of the load, and in step S220 , the external host sends a command signal CS and a mechanical command Cmd to the driver 110 .

[0052] In this embodiment, the command signal CS may be provided by an external electronic device. The command signal CS may be a mode switching command provided by an input / output (I / O) function of an external host. In other embodiments, the command signal CS may be a machining instruction (such as a G / M code) in a computer numerical control (CNC) software. The mechanical command Cmd may be a speed command, a position command, an acceleration command, or other commands related to the action of the motor. The interface for signal transmission may be any input interface without fixed restrictions.

[0053] In this embodiment, in step S230, the driver 101 can switch the working mode between the first mode and the second mode according to the command signal CS, wherein the first mode and the second mode can be the smart energy saving mode and the fine-tuning mode respectively.

[0054] Incidentally, the driver 101 of the embodiment of the present invention can also work in other modes, not limited to the above two modes. For example, the driver 101 can also work in the general mode (third mode) according to the command signal CS, wherein under the corresponding same speed information of the AC motor 102, the power consumption of the actuator 100 in the smart energy-saving mode can be lower than the power consumption in the general mode.

[0055] In the smart energy-saving mode, the driver 101 performs step S241 to set the voltage margin to the first voltage margin according to the command signal CS, generates a torque command according to the force command Cmd, and generates a magnetic flux according to the torque command and the speed information of the AC motor 102 .

[0056] In the fine-tuning mode, the driver 101 passes through step S242 to set the voltage margin to the second voltage margin and the magnetic flux to the rated magnetic flux according to the command signal CS.

[0057] In this embodiment, in step S250 , the driver 101 calculates and generates a driving voltage Vout, and then outputs the driving voltage Vout to the AC motor 102 . In step S260 , the AC motor 102 operates according to the driving voltage Vout output by the driver 101 .

[0058] In this embodiment, under the same rotation speed information of the AC motor 102 , the power consumption of the actuating device 100 in the smart energy-saving mode may be lower than the power consumption in the fine-tuning mode.

[0059] The detailed process of the driver 101 generating the driving voltage Vout will be described in detail in the subsequent implementation method.

[0060] In this embodiment, the actuator 100 can also select an applicable processing mode according to the requirements of various processing scenarios. Please refer to Table 1 below, which shows the processing modes that can be applied under different loads and different processing application scenarios according to the requirements of various scenarios. Among them, when the actuator 100 performs the cutting action of the object, light load means a situation where the external force is small, such as a lighter cutting force, and heavy load means a situation where a larger cutting force is required. When doing rough processing, the intelligent energy-saving mode can be used to reduce unnecessary excitation current when the load is light, so as to achieve energy saving; and when the load is heavy, the acceleration and deceleration performance of the AC motor 102 can be improved by reducing the set voltage margin. In contrast, when the load is light and fine processing is performed, the fine-tuning mode can be used to increase the sufficient set voltage margin and improve the working stability of the AC motor 102. Among them, the classification of precision and load in Table 1 is only an example and is not intended to limit the scope of implementation of the present invention.

[0061] Table 1

[0062]

[0063] Please note that in this embodiment, the actuator 100 can switch between the above-mentioned intelligent energy-saving mode and the finishing mode during the processing. For example, in one embodiment, the original processing flow is to first perform a transverse rough turning process (roughing) and then perform a finishing process. If the implementation method of the present invention is adopted, the intelligent energy-saving mode can be selected before starting the processing to the finishing process. During the roughing process, since the set voltage margin can be adjusted to a lower level, the AC motor 102 can have better acceleration and deceleration performance when working, and can save power consumption, thereby achieving energy-saving effects. Then, before performing the finishing process, the actuator 100 can receive a command signal CS to switch to the finishing mode. During the finishing process, since the set voltage margin can be increased and the AC motor 102 can be controlled to work at the rated operating point, the AC motor 102 can have higher stability when working to meet the requirements of the finishing process. Finally, after the finishing process is completed, the actuator 100 can also receive the command signal CS again to switch back to the intelligent energy-saving mode.

[0064] From the above description, it can be known that the actuator 100 of the embodiment of the present invention can switch between the intelligent energy-saving mode and the fine-tuning mode according to actual processing requirements, and can achieve the effects of saving power consumption, improving processing action performance and improving the working stability of the AC motor 102, thereby effectively improving the overall efficiency of the system.

[0065] About the Invention Figure 2 For details of the operation of the intelligent energy-saving mode in the embodiment, please refer to Figure 3A . Figure 3A A schematic diagram of the operation of the intelligent energy-saving mode according to an embodiment of the present invention is shown. Figure 3A In the embodiment, the external host 303_1 is used to send a command signal CS and a mechanical command Cmd to the driver 301_1, and the driver 301_1 is used to send a driving voltage Vout to drive the AC motor 302_1.

[0066] In this embodiment, the driver 301_1 sets the voltage margin to the first voltage margin VL according to the command signal CS, and generates the speed error information Verr according to the mechanical command Cmd and the speed information of the AC motor 302_1. In this embodiment, the mechanical command Cmd may be a speed command.

[0067] On the other hand, the first voltage margin VL may be the difference between the maximum driving voltage that the driver 301_1 can apply to the AC motor 302_1 and the voltage value at which the driver 301_1 determines to enter the weak magnetic control. When the mechanical command Cmd is a speed command, the speed error information Verr may be the difference between the mechanical command Cmd and the current speed information of the AC motor 302_1. When the mechanical command Cmd is a position command, the speed error information Verr may be the difference between the position command and the position feedback, and the speed command obtained after calculation.

[0068] The driver 301_1 generates a torque command Tcmd according to the speed error information Verr, and then generates a set magnetic flux Φ and torque axis current information Iq according to the torque command Tcmd. In this embodiment, the set magnetic flux Φ can be an energy-saving magnetic flux.

[0069] At the first time point t1 , the driver 301_1 generates the excitation axis current information Id according to the first voltage margin VL and the set magnetic flux Φ, and generates the current voltage command Vdq(t1) according to the excitation axis current information Id and the torque axis current information Iq.

[0070] Then, at the second time point t2, the voltage command Vdq(t1) becomes the previous voltage command. At this time, the driver 301_1 generates the current voltage command Vdq(t2) according to the excitation axis current information Id, the torque axis current information Iq and the previous voltage command Vdq(t1).

[0071] On the other hand, taking the second time point t2 as an example, the driver 301_1 can determine whether the current voltage command Vdq(t2) is greater than the maximum driving voltage that the driver 301_1 can apply to the AC motor 302_1, and when the current voltage command Vdq(t2) is greater than the maximum driving voltage, the current driving voltage Vout is made the maximum driving voltage.

[0072] In this embodiment, the driver 301_1 generates a driving voltage Vout according to the current voltage command Vdq(t2) and is used to drive the AC motor 302_1. Incidentally, the driver 301_1 can compare the current voltage command Vdq(t2) with the maximum driving voltage of the driver 301_1 to generate the driving voltage Vout. On the other hand, the driver 301_1 can select the smaller voltage value between the current voltage command Vdq(t2) and the maximum driving voltage of the driver 301_1 as the driving voltage Vout.

[0073] In this embodiment, when the actuator 100 is in a light-load processing situation, the driver 301_1 can be switched to the intelligent energy-saving mode, so that the AC motor 302_1 can work at different speeds with energy-saving effects. For example, the speed of the AC motor 302_1 can be set at 150 to 6000 revolutions (RPM). When the driver 301_1 is switched to the intelligent energy-saving mode, the value of the working current of the AC motor 302_1 can be reduced by 44% to 91% compared with the general mode, the value of the working voltage can be reduced by 63% to 91% compared with the general mode, and the value of the working power can also be increased by 80% to 99% compared with the general mode, which can successfully achieve the effect of energy saving.

[0074] About the Invention Figure 1 For details on the actions in the refinement mode in the implementation method, please refer to Figure 3B . Figure 3B A schematic diagram of the operation of the refinement mode according to an embodiment of the present invention is shown. Figure 3B and Figure 3A The operation process is similar, but the difference is that in this embodiment, the driver 301_2 sets the voltage margin to the second voltage margin VH according to the command signal CS, generates the speed error information Verr according to the mechanical command Cmd, and sets the magnetic flux Φ to the rated magnetic flux. It is worth noting that in the fine-tuning mode, the rated magnetic flux is independent of the mechanical command Cmd. In this embodiment, the mechanical command Cmd can be a speed command, and the second voltage margin VH can be a relatively high voltage margin (the second voltage margin VH>the first voltage margin VL). For other implementation methods, please refer to Figure 3A In this embodiment, because the setting voltage margin of the driver 301_2 can be increased, the AC motor 302_2 can have better stability during operation.

[0075] Regarding the selection of setting voltage margin when the above actuator works in intelligent energy-saving mode and fine-tuning mode, please also refer to Figure 4A and Figure 4B . Figure 4A , Figure 4B The operation waveform diagrams of the actuating devices according to different embodiments of the present invention are shown.

[0076] Please refer to Figure 4A .exist Figure 4A In the embodiment, the driver has a maximum driving voltage V3. When the AC motor operates under the condition of high voltage margin, the operating voltage is shown as waveform 401. When the AC motor operates under the condition of low voltage margin, the operating voltage is shown as waveform 402.

[0077] In the process of reaching time t1, both waveform 401 and waveform 402 will reach the rated speed of the AC motor. According to waveform 401 (under the condition of high voltage margin), the working voltage is maintained at working voltage V1 after time t1. According to waveform 402 (under the condition of low voltage margin), voltage saturation is reached at time t2, and the working voltage is maintained at working voltage V2 after time t2. Among them, the working voltages V1 and V2 are both less than the maximum driving voltage V3, and the working voltage V1 is less than the working voltage V2. Since the working voltage V2 is greater than the working voltage V1, after time t1, the low voltage margin will have a better acceleration. For example, the low voltage margin can reach the maximum speed at time t3, while the high voltage margin can only reach the maximum speed at time t4, and the time point when time t3 occurs is earlier than time t4.

[0078] Please note that in this embodiment, under the premise that the working voltage of the AC motor is stable during the acceleration process, and under the premise that the working voltage V1 is less than the working voltage V2, the waveform 401 has a relatively high voltage margin relative to the waveform 402.

[0079] Please also refer to Figure 4A and Figure 4B . Figure 4B for Figure 4A At the operating point after time t2, waveforms 403 and 404 are the voltage waveform changes when subjected to external disturbances. Waveform 403 shows that when the AC motor operates under the condition of high voltage margin and the AC motor is maintained at the rated maximum speed, its operating voltage is V4. Waveform 404 shows that when the AC motor operates under the condition of low voltage margin and the AC motor is maintained at the rated maximum speed, its operating voltage is V5. In the fine-tuning mode, because the voltage margin is higher, when subjected to external force disturbances, it will not be limited by the voltage upper limit (V3), and there will be enough voltage for correction; while the low voltage margin is easily limited by reaching the maximum voltage of the driver.

[0080] Therefore, based on the control embodiments of the above-mentioned intelligent energy-saving mode and fine-tuning mode, the actuator of the present invention can switch the working mode between the intelligent energy-saving mode and the fine-tuning mode according to the command signal and the mechanical command sent by the external host. In the intelligent energy-saving mode, the set voltage margin of the driver can be adjusted to a low voltage margin, so that the AC motor has better acceleration and deceleration performance when working. On the other hand, the torque command can be generated according to the mechanical command to determine the set magnetic flux for the best efficiency control, which can reduce the unnecessary loss caused by the excitation current when the load is light, and achieve the effect of improving performance and energy saving at the same time. In the fine-tuning mode, the set voltage margin of the driver can be adjusted to a high voltage margin to reduce the voltage when entering the weak magnetic control, so that the AC motor has better stability when working, and when it is disturbed by the outside world, it is less likely to be affected by the maximum driving voltage of the driver. On the other hand, before the driving voltage of the driver is not saturated, the set magnetic flux can be set to the rated magnetic flux to control the AC motor under the rated excitation current, so that the AC motor has a better working response.

[0081] Please refer to Figure 5 . Figure 5 A block diagram of a driving method according to an embodiment of the present invention is shown, and the driving method can be implemented by the aforementioned actuator. In step S510, the actuator receives a command signal and a mechanical command. In step S520, the operating mode can be switched between the first mode and the second mode according to the command signal.

[0082] In this embodiment, in step S520, when the first mode is switched according to the command signal, step S530 is entered, and step S530 includes step S531 and step S532. In step S531, the set voltage margin can be set to the first voltage margin, and in step S532, the set magnetic flux is generated according to the mechanical command and the speed information of the AC motor.

[0083] In this embodiment, in step S520, when the second mode is switched according to the command signal, step S540 is entered, and step S540 includes step S541 and step S542. In step S541, the set voltage margin can be set to the second voltage margin, and in step S542, the set magnetic flux can be set to the rated magnetic flux.

[0084] After executing step S530 or step S540, step S550 is entered to generate a torque command according to the mechanical command. In step S560, a current voltage command is generated according to the torque command, the set magnetic flux, the set voltage margin and the previous voltage command. Finally, in step S570, a driving voltage for driving the AC motor is generated according to the current voltage command.

[0085] The implementation details of the above steps have been described in detail in the aforementioned multiple embodiments and will not be elaborated here.

[0086] In summary, the actuator device proposed in the present invention can be applied to induction motors and different processing scenarios through a driver with an open switching control mode, so that the external device can dynamically switch between the intelligent energy-saving mode and the fine-tuning mode during the processing. Among them, the intelligent energy-saving mode can reduce the set voltage margin and have good acceleration and deceleration performance. When applied under different loads, the set magnetic flux can also be reduced to achieve energy-saving effects. When used in transient heavy loads and acceleration and deceleration requirements, the set magnetic flux control operation can also be adjusted in real time to exceed the rated point of the motor, with lower losses. In contrast, the fine-tuning mode can increase the set voltage margin and can be used in low-load environments requiring high stability. Therefore, the actuator device and driving method proposed in the present invention can simultaneously improve the performance, energy saving and stability of the processing action by dynamically switching the above two driver modes.

[0087] Explanation of symbols:

[0088] 100: actuating device;

[0089] 101, 301_1, 301_2: driver;

[0090] 102, 302_1, 302_2: AC motor;

[0091] 303_1, 303_2: external host;

[0092] 401, 402, 403: waveform;

[0093] CS: command signal;

[0094] Cmd: mechanics command;

[0095] Id, Iq: current information;

[0096] S210-S260, S510-S570: steps;

[0097] t1, t2: time;

[0098] Tcmd: torque command;

[0099] V1~V4, Vout: voltage;

[0100] Vdq(t1), Vdq(t2): voltage command;

[0101] Verr: speed error information;

[0102] VH, VL: voltage margin;

[0103] Φ: Set magnetic flux.

[0104] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. An actuating device, characterized in that: It includes: an AC motor, the AC motor receiving a driving voltage; a driver driving the AC motor, the driver switching between a first mode and a second mode according to a command signal, generating a torque command according to a force command, generating a current voltage command according to the torque command, a set magnetic flux, a set voltage margin and a previous voltage command, and generating the driving voltage according to the current voltage command; When the driver is in the first mode, the driver is used to: setting the first voltage margin as the set voltage margin according to the command signal; and, generating the set magnetic flux according to the mechanical command and the speed information of the AC motor; When the driver is in the second mode, the driver is used to: setting a second voltage margin as the set voltage margin according to the command signal, the first voltage margin being smaller than the second voltage margin; and, The set magnetic flux is made equal to the rated magnetic flux.

2. The actuating device according to claim 1, characterized in that: The driver is used for generating speed error information according to the mechanical command and the speed information of the AC motor, and generating the torque command according to the speed error information.

3. The actuating device according to claim 1, characterized in that: The driver obtains the excitation axis current information according to the set voltage margin, the set magnetic flux and the previous voltage command, obtains the torque axis current information according to the torque command, and generates the current voltage command according to the excitation axis current information and the torque axis current information.

4. The actuating device according to claim 1, characterized in that: The driver further includes determining whether the driving voltage generated by the current voltage command is greater than a maximum driving voltage, and making the driving voltage equal to the maximum driving voltage when the driving voltage is greater than the maximum driving voltage.

5. The actuating device according to claim 1, characterized in that: When corresponding to the same rotation speed information of the AC motor, the power consumption of the actuator in the first mode is less than or equal to the power consumption in the second mode.

6. The actuating device according to claim 1, characterized in that: The driver also operates in a third mode which is a general mode according to the command signal; corresponding to the same AC motor speed information, the power consumption of the actuator in the first mode is less than its power consumption in the third mode.

7. A driving method for causing a driver to drive an AC motor, characterized in that: It includes the following steps: switching between a first mode and a second mode according to a command signal; Generate torque command according to mechanical command; generating a current voltage command according to the torque command, the set magnetic flux, the set voltage margin and the previous voltage command; as well as, generating a driving voltage for driving the AC motor according to the current voltage command; When the driver is in the first mode, the driver is used to: setting the first voltage margin as the set voltage margin according to the command signal; and, generating the set magnetic flux according to the mechanical command and the speed information of the AC motor; When the driver is in the second mode, the driver is used to: setting a second voltage margin as the set voltage margin according to the command signal, the first voltage margin being smaller than the second voltage margin; and, The set magnetic flux is made equal to the rated magnetic flux.

8. The driving method according to claim 7, characterized in that: The steps of generating a torque command according to a mechanical command include: generating speed error information according to the mechanical command and the speed information of the AC motor; and, The torque command is generated according to the rotation speed error information.

9. The driving method according to claim 7, characterized in that: The steps of generating a current voltage command according to the torque command, setting the magnetic flux, setting the voltage margin and the previous voltage command include: obtaining exciting shaft current information according to the set voltage margin, the set magnetic flux and the previous voltage command; and, Torque shaft current information is obtained according to the torque command.

10. The driving method according to claim 7, characterized in that: It also includes the following steps: Determining whether the driving voltage generated by the current voltage command is greater than a maximum driving voltage; and, When the driving voltage is greater than the maximum driving voltage, the driving voltage is made equal to the maximum driving voltage.

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