Servo driver current loop bandwidth expansion method and servo driver
By measuring the maximum calculation time of each ring in the servo driver current ring, determining the trigger point and conditions, and realizing multiple current ring calculations and duty cycle updates, the problem of insufficient response speed of the traditional current ring is solved, and the dynamic performance and control accuracy of the servo system are significantly improved.
Patent Information
- Application Number
- CN202411975530.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-04-15
AI Technical Summary
The response speed of the current loop of the traditional servo driver is limited, resulting in insufficient tracking capability for rapidly changing current instructions, affecting the dynamic response performance and control accuracy of the servo system.
By measuring the maximum calculation time of the position ring, speed ring and current ring offline, determining the trigger point and trigger conditions during the control cycle, multiple current ring calculations and duty cycle updates are realized, thereby eliminating the inherent delay in the control cycle.
It effectively expands the bandwidth of the current loop, improves the tracking ability of rapidly changing current instructions, significantly improves the dynamic response performance and control accuracy of the servo system, and reduces response time and steady-state error.
Smart Images
Figure CN119834684A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of servo motor control, and specifically relates to a servo driver current loop bandwidth expansion method and a servo driver. Background Art
[0002] The control structure of a servo drive usually includes a position loop, a speed loop, and a current loop, which work in series. As the innermost control loop, the current loop directly responds to the given current command and regulates the actual current of the motor, which is crucial to the dynamic response performance of the servo system, especially for the fast and accurate response to the position command.
[0003] In order to improve the position response performance of the servo drive, widening the bandwidth of the current loop is the key. Traditionally, in each PWM (pulse width modulation) cycle, the system samples the current and electrical angle information once, and calculates a new duty cycle value through the controller and applies it at the beginning of the next PWM cycle, but this method limits the response speed of the current loop. Summary of the invention
[0004] In order to solve the above problems, the main purpose of the present application is to provide a servo drive current loop bandwidth expansion method and a servo drive. The present application aims to expand the servo drive current loop bandwidth while solving the problems existing in the prior art.
[0005] To achieve the above objectives, this application provides the following technical solutions:
[0006] A method for expanding the bandwidth of a current loop of a servo drive comprises: for a current control cycle, measuring the maximum calculation time of a position loop, a speed loop and a current loop respectively offline; determining a trigger point and a corresponding trigger condition in the current control cycle based on the obtained maximum calculation time of each control loop; triggering current loop calculation in the current control cycle based on the trigger point and the corresponding trigger condition, and immediately updating and applying the duty cycle of a control signal in the current control cycle according to the calculation result.
[0007] Optionally, based on the obtained maximum calculation time of each control loop, the trigger point and the corresponding trigger condition in the current control cycle are determined, including: setting a first trigger point at the trough moment of the control signal and determining a first trigger condition corresponding to the first trigger point, and setting a second trigger point at the peak moment of the control signal and determining a second trigger condition corresponding to the second trigger point.
[0008] Optionally, determining the first trigger condition corresponding to the first trigger point includes: setting a first control signal count value and a second control signal count value; when the control signal count value counts down to equal the first control signal count value, collecting the position of the servo motor and triggering the position loop and speed loop calculation of the servo drive; when the control signal count value counts down to equal the second control signal count value, collecting the phase current of the servo motor and triggering the current loop calculation.
[0009] Optionally, determining a second trigger condition corresponding to the second trigger point includes: setting a third control signal count value; when the control signal count value counts up to equal the third control signal count value, collecting the phase current of the servo motor again and triggering the current loop calculation with electrical angle delay compensation.
[0010] Optionally, after the phase current of the servo motor is collected and the current loop calculation is triggered, the first duty cycle of the control signal is obtained according to the calculation result.
[0011] Optionally, after the phase current of the servo motor is collected again and the current loop calculation with electrical angle delay compensation is triggered, the first duty cycle of the control signal is updated according to the calculation result to obtain the second duty cycle of the control signal.
[0012] The present application also provides a servo drive, which includes: a measurement module, which is used to offline measure the maximum calculation time of the position loop, the speed loop and the current loop for the current control cycle; a determination module, which is used to determine the trigger point and the corresponding trigger condition within the current control cycle based on the obtained maximum calculation time of each control loop; a calculation and update module, which is used to trigger the current loop calculation within the current control cycle based on the trigger point and the corresponding trigger condition, and immediately update and apply the duty cycle of the control signal of the current control cycle according to the calculation result.
[0013] Optionally, the determination module includes: a first determination submodule, used to set a first trigger point at the trough moment of the control signal and determine a first trigger condition corresponding to the first trigger point; a second determination submodule, used to set a second trigger point at the peak moment of the control signal and determine a second trigger condition corresponding to the second trigger point.
[0014] Optionally, the calculation and update module includes: a first calculation and update submodule, which is used to obtain a first duty cycle of the control signal according to the calculation result after collecting the phase current of the servo motor and triggering the current loop calculation.
[0015] Optionally, the calculation and update module also includes: a second calculation and update sub-module, which is used to update the first duty cycle of the control signal according to the calculation result after the phase current of the servo motor is collected again and the current loop calculation with electrical angle delay compensation is triggered to obtain the second duty cycle of the control signal.
[0016] The present application can bring the following beneficial effects: The present application effectively eliminates the inherent delay of half or one control cycle by setting multiple trigger points in each control cycle and performing two current loop calculations and corresponding duty cycle updates based on these trigger points. The present application not only realizes the effective expansion of the current loop bandwidth and improves the current loop's tracking capability for rapidly changing current instructions, but also significantly improves the dynamic response performance and control accuracy of the servo system, which is specifically manifested in shortened response time, increased current loop bandwidth, reduced steady-state error, and reduced current overshoot, thereby enhancing the position tracking capability and stability of the servo drive. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 It is a flow chart of a method for expanding the bandwidth of a servo drive current loop provided by an embodiment of the present application;
[0018] Figure 2 is a schematic diagram of a PWM control cycle timing sequence provided by another embodiment of the present application;
[0019] Figure 3 is a schematic diagram of a q-axis current step response curve provided by another embodiment of the present application;
[0020] Figure 4 It is a structural schematic diagram of a servo driver provided in another embodiment of the present application. DETAILED DESCRIPTION
[0021] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0022] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0023] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.
[0024] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.
[0025] Figure 1 FIG. 1 is a flow chart of a method for expanding the current loop bandwidth of a servo drive according to an embodiment of the present application, such as Figure 1 As shown, the method comprises the following steps:
[0026] S100: for a current control cycle (eg, a PWM control cycle), using a DSP (digital signal processor) to measure the maximum calculation time of the position loop, the speed loop, and the current loop of the servo drive in an offline state;
[0027] In this step, after obtaining the maximum calculation time of the position loop and the speed loop offline, a certain safety margin needs to be added on this basis (for example, adding 5% on the basis of the maximum calculation time of the position loop and the speed loop) to obtain the final calculation time of the position loop and the speed loop, which is recorded as t a Similarly, after obtaining the maximum calculation time of the current loop offline, it is necessary to add a certain safety margin on this basis (for example, add 5% on the basis of the maximum calculation time of the current loop) to obtain the final calculation time of the current loop, which is recorded as t bIt should be noted that the reason why a certain safety margin needs to be added to the maximum calculation time of each loop is to ensure that in actual operation, there is enough buffer time to cope with possible changes or fluctuations, so as to ensure that the position loop, speed loop and current loop calculations can be completed before a specific time point in the control cycle.
[0028] It should be noted that the maximum calculation time refers to the maximum time required for the position loop, speed loop and current loop to complete a complete calculation. Specifically:
[0029] The maximum calculation time of the position loop refers to the longest time required from obtaining the position information fed back by the position sensor to completing the position error calculation, position controller operation (such as PID control), and outputting the speed command to the speed loop.
[0030] The maximum calculation time of the speed loop is the longest time required from receiving the speed command of the position loop, through speed error calculation, speed controller operation, and then outputting the current command to the current loop.
[0031] The maximum calculation time of the current loop refers to the maximum time from receiving the current command from the speed loop, performing phase current sampling, current error calculation, current controller operation, and finally updating the duty cycle of the control signal within the control cycle and acting on the motor.
[0032] The reason for offline measurement of the maximum calculation time of each control loop is to ensure that in the actual control process, each control loop can complete its calculation task before the next control cycle arrives, and has enough time margin to deal with possible calculation delays or fluctuations, which helps to ensure the real-time and stability of the system and avoid performance degradation or system instability caused by untimely calculation. By understanding the maximum calculation time of each control loop, the trigger point and the corresponding trigger conditions can be reasonably arranged so that the current loop calculation can be effectively triggered in each control cycle, and the duty cycle of the control signal can be updated instantly according to the calculation results. The purpose of this is to eliminate the inherent delay of half or one control cycle, thereby achieving effective expansion of the current loop bandwidth, improving the current loop's ability to track rapidly changing current instructions, and improving the dynamic response performance and control accuracy of the servo drive.
[0033] S200: Determine a trigger point and a corresponding trigger condition within a current control cycle based on the obtained maximum calculation time of each control loop;
[0034] S300: Based on the trigger point and the corresponding trigger condition, trigger the current loop calculation in the current control cycle, and immediately update and apply the duty cycle of the control signal in the current control cycle according to the calculation result.
[0035] This application measures the maximum calculation time of the position loop, speed loop and current loop offline, and sets different trigger points and corresponding trigger conditions in each control cycle based on these times, so that the current loop can be triggered multiple times in each control cycle to calculate and update the duty cycle of the control signal in real time. This application can effectively eliminate the inherent delay of half or one control cycle, thereby significantly improving the current loop's ability to track rapidly changing current instructions.
[0036] In another exemplary embodiment, in step S200, the trigger point and the corresponding trigger condition in the current control cycle are determined based on the obtained maximum calculation time of each control loop, including: setting a first trigger point at the trough moment of the control signal and determining a first trigger condition corresponding to the first trigger point, and setting a second trigger point at the peak moment of the control signal and determining a second trigger condition corresponding to the second trigger point.
[0037] In this embodiment, in each control cycle, Figure 2 As shown, the present application records the time when the trough of the control signal (such as the PWM signal) appears as t n , and set it as the first trigger point at this moment; in addition, the moment when the control signal peak appears is recorded as t n+1 , and set it as the second trigger point at this moment.
[0038] Specifically, at the first trigger point (trough time t n ), it is necessary to set the corresponding first trigger condition, which includes: setting CMPB (i.e., in advance of the trough time t n The time point is denoted as t n -(t a +t b )) is the first control signal count value (CMPB is used to ensure that the calculation of the position loop and the speed loop can be completed before the trough moment within the control cycle to avoid affecting the start of the next cycle). When the control signal count value counts down (starting from a preset maximum value, the counter gradually decreases until it reaches 0 or a minimum value. In the down counting mode, when the count value is equal to the comparison value corresponding to the preset duty cycle, the PWM output switches from a high level to a low level, and the counter continues to decrease until a cycle ends) is equal to CMPB, the P value of the servo motor position is collected. n And trigger the calculation of the position loop and speed loop of the servo drive. And set CMPC (i.e., in advance of the trough time t n The time point is denoted as t n -t b ) is the second control signal count value. When the control signal count value is counted down to CMPC, the phase current of the servo motor is collected and the current loop calculation is triggered.
[0039] At the second trigger point (peak time t n+1 ), it is necessary to set the corresponding second trigger condition, which includes: setting CMPD (i.e., in advance of the peak time t n+1 The time point is denoted as t n+1 -t b ) is the count value of the third control signal. When the count value of the control signal counts up (starting from 0 or a minimum value, the counter gradually increases until it reaches the preset maximum value. In the up-counting mode, when the count value is equal to the comparison value corresponding to the preset duty cycle, the PWM output switches from a low level to a high level, and the counter continues to increase until a cycle ends) is equal to CMPD, the phase current of the servo motor is collected again and the current loop calculation with electrical angle delay compensation is triggered.
[0040] In another exemplary embodiment, in step S300, when the control signal count value is counted down to CMPC, the phase current of the servo motor is immediately acquired, and the current loop calculation is triggered, and the first duty cycle D of the control signal is obtained according to the calculation result. n .
[0041] In this embodiment, the first duty cycle D is obtained according to the calculation result. n , specifically including the following steps:
[0042] First, the difference between the expected current value and the actual measured phase current, that is, the error, is calculated, which is specifically expressed as follows:
[0043] e(t)=I cmd (t)-I actual (t)
[0044] Where e(t) is the error signal, which indicates the difference between the expected current and the actual current at time t, I cmd (t) represents the expected current, I actual (t) represents the actual measured phase current.
[0045] Secondly, the error is processed using a PID (proportional-integral-derivative) controller or other type of controller to generate a control signal. This control signal will be used to adjust the voltage applied to the motor, thereby changing the motor's current. The output of the PID controller can be expressed as:
[0046]
[0047] Where u(t) represents the controller output, that is, the duty cycle increment that needs to be adjusted, K p Represents the proportional gain coefficient, K i Indicates the integral gain coefficient, K d represents the differential gain coefficient, e(t) represents the error signal, is the integral term, which represents the cumulative sum of all errors from the starting time to the current time. is the differential term, which represents the rate of change of error over time.
[0048] Finally, the duty cycle is calculated based on the output of the controller, as follows:
[0049] D n =D old +ΔD
[0050] Among them, D n Denotes the first duty cycle, D old represents the current duty cycle, and ΔD represents the duty cycle increment.
[0051] In another exemplary embodiment, in step S300, when the control signal count value is counted up to be equal to CMPD, the phase current of the servo motor is collected again, and the current loop calculation with electrical angle delay compensation is triggered, and the first duty cycle D is calculated according to the calculation result. n Update to obtain a new duty cycle, i.e., the second duty cycle D n+1 .
[0052] In this embodiment, the second duty cycle D n+1 and the first duty cycle D n The calculation process is similar, both of which are based on the current loop controller (such as PID controller) processing the error signal to obtain a new control signal, and update the duty cycle of the control signal accordingly.
[0053] However, it should be noted that the second duty cycle D n+1 and the first duty cycle D n The difference is: First, the sampling time is different: First, the duty cycle D n It is calculated before the trough moment of the control cycle. At this time, the position of the servo motor is collected and the position loop and speed loop calculation are triggered. Then the phase current is collected and the current loop calculation is triggered. The second duty cycle D n+1 It is calculated by collecting the phase current again and triggering the current loop with electrical angle delay compensation before the peak moment in the same control cycle. n It is calculated at or near the beginning of the control cycle and used for the current control cycle. n+1 It is calculated at a later time in the same control cycle and is immediately applied to the remainder of the current control cycle, thus reducing the inherent delay of half a control cycle.
[0054] The electrical angle delay compensation is calculated based on the following formula:
[0055] θ cmp_n =(p n -p n-2 ) / 2*n p
[0056] Among them, p n-2 The position of the servo motor obtained in the last cycle, n p is the number of motor pole pairs.
[0057] It should be noted that the present application can more accurately predict and compensate for the current response delay caused by mechanical inertia and electromagnetic inertia by triggering the current loop calculation with electrical angle delay compensation, thereby improving the dynamic performance and control accuracy of the control system. Specifically: In a servo drive system, when a new position or speed command is given, the actual current response of the motor may be delayed to a certain extent due to the existence of mechanical inertia and electromagnetic inertia. This delay will affect the current loop's tracking effect on command changes, and thus affect the response speed and accuracy of the entire servo system. By introducing electrical angle delay compensation, the present application can take these delay factors into account in advance when calculating the current loop, so that the calculation results are closer to the actual situation.
[0058] In the traditional method, the duty cycle D n It is usually calculated at the trough moment of a control cycle, but is applied at the peak moment or the trough moment of the next control cycle, resulting in an update delay of half or one control cycle, making it difficult for the servo control system to respond to changes in the motor current in a timely manner, thereby limiting the bandwidth of the current loop. n The time point before (t n -t b -t a ) Obtain the motor position and phase current data in advance, and immediately perform current loop calculation and obtain the duty cycle D of the control signal n , then at the next trough time t n The duty cycle is applied immediately, and at the peak time t of the same control cycle n+1 The time point before (t n+1 -t b ) collects phase current data again, triggers the current loop calculation and applies half-cycle electrical angle delay compensation to obtain and n+1 Immediately applied relative to the duty cycle D n Updated duty cycle D n+1That is, the present application performs two current loop calculations by setting trigger points before the trough and peak moments within a control cycle, and immediately applies the corresponding duty cycle update within the current control cycle, essentially doubling the update frequency, allowing the servo control system to adjust the drive signal more frequently in response to current changes, thereby improving the response speed of the current loop.
[0059] In addition, the present application can more accurately predict and compensate for the current response delay caused by mechanical inertia and electromagnetic inertia by performing current loop calculation with electrical angle delay compensation at the trigger point before the peak moment, thereby further improving the control accuracy.
[0060] In summary, by repeatedly executing the above steps, the present application can perform two current loop calculations and corresponding duty cycle updates in each control cycle, which not only eliminates the inherent delay of half or one control cycle, but also achieves effective expansion of the current loop bandwidth. The effective expansion of the current loop bandwidth means that the current loop can better track rapidly changing current commands, so that the servo drive can respond to changes in position commands more quickly, thereby improving the dynamic performance and control accuracy of the control system.
[0061] Below, in order to more intuitively demonstrate the advantages of the method described in this application over the traditional method, this application is specifically explained through the following examples: the above two different current loop control strategies are applied in the servo control system of an industrial robot joint. The test environment is set as follows: Motor type: permanent magnet synchronous motor (PMSM); Controller hardware: servo drive equipped with DSP chip; Test conditions: The robot joint performs position tracking tasks under a fixed load, using the same mechanical structure and load conditions. Assuming that this joint needs to quickly and accurately track changes in position instructions, Table 1 is the test data obtained based on this method and the traditional method:
[0062] Table 1
[0063] index Traditional methods This method Response time (ms) 20 15 Current loop bandwidth (kHz) 1 1.5 Steady state error (degrees) ±0.5 ±0.2 q-axis current overshoot (%) 20％ 10％
[0064] In Table 1, compared with the traditional method, the method described in the present application triggers two current loop calculations before the trough and before the peak in each control cycle, and immediately applies the corresponding duty cycle update, thereby eliminating the inherent delay of half or one control cycle, and reducing the response time from 20ms to 15ms, so that the robot joint can track the changes in position instructions more quickly. Through Bode diagram analysis, the current loop bandwidth obtained by the traditional method is about 1kHz, while the current loop bandwidth obtained by the present method is increased to 1.5kHz, thereby improving the dynamic response capability of the robot joint. In addition, due to more frequent and timely current adjustment, compared with the traditional method, the steady-state error of the present method is reduced to ±0.2 degrees. In addition, the present method significantly reduces the current overshoot, reducing the overshoot from 20% to 10%, thereby improving the accuracy and smoothness of the robot joint position control.
[0065] Figure 3 is a schematic diagram of the q-axis current step response curve under the traditional method and this method, Figure 3 It can be seen that: 1. The curve under this method shows a faster rising edge, indicating that the system can respond to changes in position commands in a shorter time; 2. The current waveform peak under this method is lower, proving that the overshoot phenomenon is effectively suppressed; 3. The current under this method reaches the steady-state value faster and has almost no oscillation, showing better stability.
[0066] In summary, Figure 3 This clearly reflects the significant advantages of the method described in this application over the traditional method in q-axis current step response. By increasing the current loop bandwidth, reducing response delay, reducing overshoot and shortening stabilization time, this method can significantly improve the dynamic performance and control accuracy of the servo control system.
[0067] In another exemplary embodiment, Figure 4 As shown, the present application also provides a servo drive, including: a measurement module 100, used to measure the maximum calculation time of the position loop, the speed loop and the current loop offline for the current control cycle; a determination module 200, used to determine the trigger point and the corresponding trigger condition within the current control cycle based on the obtained maximum calculation time of each control loop; a calculation and update module 300, used to trigger the current loop calculation within the current control cycle based on the trigger point and the corresponding trigger condition, and immediately update and apply the duty cycle of the control signal of the current control cycle according to the calculation result.
[0068] Optionally, the determination module includes: a first determination submodule, used to set a first trigger point at the trough moment of the control signal and determine a first trigger condition corresponding to the first trigger point; a second determination submodule, used to set a second trigger point at the peak moment of the control signal and determine a second trigger condition corresponding to the second trigger point.
[0069] Optionally, the calculation and update module includes: a first calculation and update submodule, which is used to obtain a first duty cycle of the control signal according to the calculation result after collecting the phase current of the servo motor and triggering the current loop calculation.
[0070] Optionally, the calculation and update module also includes: a second calculation and update sub-module, which is used to update the first duty cycle of the control signal according to the calculation result after the phase current of the servo motor is collected again and the current loop calculation with electrical angle delay compensation is triggered to obtain the second duty cycle of the control signal.
[0071] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.
[0072] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.
Claims
1. A method for expanding the bandwidth of a servo drive current loop, characterized in that: The method comprises: For the current control cycle, the maximum calculation time of the position loop, speed loop and current loop is measured offline respectively; Based on the obtained maximum calculation time of each control loop, determining the trigger point and the corresponding trigger condition in the current control cycle; Based on the trigger point and the corresponding trigger condition, the current loop calculation is triggered in the current control cycle, and the duty cycle of the control signal in the current control cycle is immediately updated and applied according to the calculation result.
2. A servo drive current loop bandwidth expansion method according to claim 1, characterized in that: The determining of the trigger point and the corresponding trigger condition in the current control cycle based on the obtained maximum calculation time of each control loop includes: A first trigger point is set at a trough moment of the control signal and a first trigger condition corresponding to the first trigger point is determined, and a second trigger point is set at a peak moment of the control signal and a second trigger condition corresponding to the second trigger point is determined.
3. A servo drive current loop bandwidth expansion method according to claim 2, characterized in that: Determining the first trigger condition corresponding to the first trigger point includes: Setting a first control signal count value and a second control signal count value; When the control signal count value is counted down to equal the first control signal count value, the position of the servo motor is collected and the position loop and speed loop calculation of the servo drive are triggered; When the control signal count value is counted down to equal the second control signal count value, the phase current of the servo motor is collected and the current loop calculation is triggered.
4. A servo drive current loop bandwidth expansion method according to claim 2, characterized in that: Determining a second trigger condition corresponding to the second trigger point includes: Setting a third control signal count value; When the control signal count value counts up to equal the third control signal count value, the phase current of the servo motor is collected again and the current loop calculation with electrical angle delay compensation is triggered.
5. A servo drive current loop bandwidth expansion method according to claim 3, characterized in that: After the phase current of the servo motor is collected and the current loop calculation is triggered, the first duty cycle of the control signal is obtained according to the calculation result.
6. A servo drive current loop bandwidth expansion method according to claim 4, characterized in that: After the phase current of the servo motor is collected again and the current loop calculation with electrical angle delay compensation is triggered, the first duty cycle of the control signal is updated according to the calculation result to obtain the second duty cycle of the control signal.
7. A servo driver, characterized in that: The servo drive comprises: A measurement module is used to measure the maximum calculation time of the position loop, the speed loop and the current loop offline for the current control cycle; A determination module, used to determine a trigger point and a corresponding trigger condition within a current control cycle based on the obtained maximum calculation time of each control loop; The calculation and update module is used to trigger the current loop calculation in the current control cycle based on the trigger point and the corresponding trigger condition, and immediately update and apply the duty cycle of the control signal of the current control cycle according to the calculation result.
8. A servo driver according to claim 7, characterized in that: The determination module comprises: A first determining submodule, configured to set a first trigger point at a trough moment of the control signal and determine a first trigger condition corresponding to the first trigger point; The second determining submodule is used to set a second trigger point at the peak moment of the control signal and determine a second trigger condition corresponding to the second trigger point.
9. A servo driver according to claim 7, characterized in that: The calculation and update module includes: The first calculation and update submodule is used to obtain a first duty cycle of the control signal according to the calculation result after collecting the phase current of the servo motor and triggering the current loop calculation.
10. A servo driver according to claim 7, characterized in that: The calculation and update module also includes: The second calculation and update submodule is used to update the first duty cycle of the control signal according to the calculation result after the phase current of the servo motor is collected again and the current loop calculation with electrical angle delay compensation is triggered to obtain the second duty cycle of the control signal.