Current protection method for motor control

Abstract

The invention provides a current protection method for motor control, and relates to the technical field of motor control, and the method comprises the steps: carrying out the filtering processing of a bus current; judging whether the bus current is greater than an over-current threshold value or not, if so, performing the next step, and if not, not performing current protection; converting the bus current value into a speed equivalent value; the speed equivalent value serves as a feedback item to be introduced into speed closed-loop control, and a motor control instruction is obtained; and according to the motor control instruction, adjusting the motor speed and reducing the bus current. According to the method, a bus current signal is converted into a speed correction value and the like, the speed correction value and the like are introduced into a speed closed loop in a feedback term mode, the bus current change can be pre-judged in advance, current protection is achieved in a closed loop mode, and the accuracy of current protection and the safety of motor control are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular provides a current protection method for motor control. Background Art

[0002] With the development of all-electric aircraft, a large number of high-voltage motors are used to control the landing gear, wing surfaces and other mechanisms of all-electric aircraft. For motor control, current protection is the most critical protection measure, which ensures the safety of motors and motor controllers. The current protection method commonly used for motor control is to monitor the bus current or phase current in real time, and cut off the motor control output when the bus current or phase current is greater than the overcurrent threshold.

[0003] According to the use scenario of retracting and extending the landing gear of an all-electric aircraft, the operating condition that may cause motor overcurrent during use is the jamming of the landing gear retraction mechanism. At this time, the motor is in a high-speed and high-current working state. When the landing gear retraction mechanism is stuck, it will cause the bus current to increase rapidly. At this time, the commonly used overcurrent protection method cannot effectively and timely suppress the bus current. It is necessary to predict the bus current change in advance and suppress the continuous rise of the bus current in advance, thereby preventing the current from overcurrent.

[0004] In the prior art, the current protection measures commonly used in all-electric aircraft are to monitor the bus current or phase current of the motor in real time, and set the overcurrent threshold. When the bus current or phase current of the motor exceeds the overcurrent threshold, the current protection mechanism is triggered to suppress the increase of current by cutting off the motor control output and the motor drive power supply, thereby protecting the safety of the motor and the drive circuit. However, the method of only monitoring the bus current and phase current of the motor and cutting off the motor control output and the motor drive power supply when the bus current or phase current is greater than the overcurrent threshold has the following technical disadvantages: a) causing the motor to stop suddenly, causing damage to the motor and related mechanisms; b) transient overcurrent cannot be monitored, and no protection can be provided for the motor controller and the motor. Summary of the invention

[0005] The purpose of this application is to protect the current during motor operation, prevent the motor current from overcurrent causing damage to the current controller, and improve the safety of motor control. A current protection method is proposed that introduces the bus current signal into the speed closed loop.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: a current protection method for motor control, the method comprising:

[0007] Filter the bus current;

[0008] Determine whether the bus current is greater than the overcurrent threshold value. If so, proceed to the next step. If not, do not perform current protection.

[0009] Convert bus current values ​​to speed equivalent values;

[0010] The speed equivalent value is introduced as a feedback item into the speed closed-loop control to obtain the motor control command;

[0011] According to the motor control instructions, the motor speed is adjusted to reduce the bus current.

[0012] The current protection method for motor control provided by the present invention also has the following technical feature: the overcurrent threshold value is 75% of the rated current of the motor.

[0013] The current protection method for motor control provided by the present invention also has such a technical feature that the conversion of the bus current value into a speed equivalent value comprises:

[0014] Calculate the conversion ratio coefficient kp_cur;

[0015] According to the conversion ratio coefficient kp_cur, the bus current value is converted into the speed equivalent value speed_cur.

[0016] The current protection method for motor control provided by the present invention also has the following technical feature: the conversion ratio coefficient kp_cur is:

[0017] kp_cur=speed_max÷(cur_max–cur_over_limit)

[0018] Among them, speed_max is the maximum target speed; cur_max is the maximum allowable current; cur_over_limit is the overcurrent threshold.

[0019] The current protection method for motor control provided by the present invention also has such a technical feature that the speed equivalent value speed_cur is:

[0020] speed_cur=kp_cur×cur_feedback

[0021] Where cur_feedback is the feedback bus current; kp_cur is the current conversion proportional coefficient.

[0022] The current protection method for motor control provided by the present invention also has such a technical feature that the speed equivalent value is introduced into the speed closed-loop control as a feedback item, and the speed closed-loop output value ctrl_out is:

[0023] ctrl_out=kp×delta_speed(n)+ki×(delta_speed(n)-delta_speed(n-1)),

[0024] Among them, delta_speed(n) is the current speed difference, delta_speed(n-1) is the speed difference of the previous beat, kp is the speed closed loop proportional coefficient, ki is the speed closed loop integral coefficient,

[0025] The current speed difference delta_speed(n) is:

[0026] delta_speed(n)=speed_target–speed_feedback–speed_cur,

[0027] Among them, speed_target is the target speed, speed_feedback is the feedback speed, and speed_cur is the speed equivalent value.

[0028] Beneficial Effects

[0029] The current protection method for motor control proposed in the present invention converts the bus current signal into speed correction values ​​and introduces it into the speed closed loop in the form of feedback items. It can predict the bus current changes in advance and realize current protection in a closed loop manner, thereby improving the accuracy of current protection and the safety of motor control. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A flow chart of the current protection method for motor control provided by the present invention;

[0032] Figure 2 A schematic diagram of the relationship between bus current and target speed provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of the relationship between current protection and speed closed loop provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The present application is further described in detail below in conjunction with the accompanying drawings and examples, but it should be noted that these implementation methods are not limitations of the present application, and equivalent changes or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these implementation methods are all within the scope of protection of the present application.

[0035] In the description of the embodiments of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the creation of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the creation of the present application.

[0036] In addition, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0037] The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it 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, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention of this application can be understood by specific circumstances.

[0038] like Figure 1-3 As shown, an embodiment of the present application provides a current protection method for motor control, the method comprising:

[0039] Filter the bus current;

[0040] Determine whether the bus current is greater than the overcurrent threshold value. If so, proceed to the next step. If not, do not perform current protection.

[0041] Convert bus current values ​​to speed equivalent values;

[0042] The speed equivalent value is introduced as a feedback item into the speed closed-loop control to obtain the motor control command;

[0043] According to the motor control instructions, the motor speed is adjusted to reduce the bus current.

[0044] In some embodiments, the overcurrent threshold is 75% of the rated current of the motor.

[0045] In some embodiments, converting the bus current value into a speed equivalent value includes:

[0046] Calculate the conversion ratio coefficient kp_cur;

[0047] According to the conversion ratio coefficient kp_cur, the bus current value is converted into the speed equivalent value speed_cur.

[0048] In some embodiments, the conversion ratio coefficient kp_cur is:

[0049] kp_cur=speed_max÷(cur_max–cur_over_limit)

[0050] Among them, speed_max is the maximum target speed; cur_max is the maximum allowable current; cur_over_limit is the overcurrent threshold.

[0051] In some embodiments, the speed equivalent value speed_cur is:

[0052] speed_cur=kp_cur×cur_feedback

[0053] Wherein, cur_feedback is the feedback bus current; kp_cur is the current conversion proportional coefficient.

[0054] In some embodiments, the speed equivalent value is introduced into the speed closed-loop control as a feedback term, and the speed closed-loop output value ctrl_out is:

[0055] ctrl_out=kp×delta_speed(n)+ki×(delta_speed(n)-delta_speed(n-1)),

[0056] Among them, delta_speed(n) is the current speed difference, delta_speed(n-1) is the speed difference of the previous beat, kp is the speed closed loop proportional coefficient, ki is the speed closed loop integral coefficient, and the current speed difference delta_speed(n) is:

[0057] delta_speed(n)=speed_target–speed_feedback–speed_cur,

[0058] Among them, speed_target is the target speed, speed_feedback is the feedback speed, and speed_cur is the speed equivalent value.

[0059] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application. The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present application, and these improvements and variations should also be regarded as the protection scope of the present application.

Claims

1. A current protection method for motor control, characterized in that: The method comprises: Filter the bus current; Determine whether the bus current is greater than the overcurrent threshold value. If so, proceed to the next step. If not, do not perform current protection. Convert bus current values ​​to speed equivalent values; The speed equivalent value is introduced as a feedback item into the speed closed-loop control to obtain the motor control command; According to the motor control instructions, the motor speed is adjusted to reduce the bus current.

2. The current protection method for motor control according to claim 1, characterized in that: The over-current threshold value is 75% of the rated current of the motor.

3. The current protection method for motor control according to claim 1, characterized in that: The converting of the bus current value into a speed equivalent value comprises: Calculate the conversion ratio coefficient kp_cur; According to the conversion ratio coefficient kp_cur, the bus current value is converted into the speed equivalent value speed_cur.

4. The current protection method for motor control according to claim 3, characterized in that: The conversion ratio coefficient kp_cur is: kp_cur=speed_max÷(cur_max–cur_over_limit) Among them, speed_max is the maximum target speed; cur_max is the maximum allowable current; cur_over_limit is the overcurrent threshold.

5. The current protection method for motor control according to claim 3, characterized in that: The speed equivalent value speed_cur is: speed_cur=kp_cur×cur_feedback Where cur_feedback is the feedback bus current; kp_cur is the current conversion proportional coefficient.

6. The current protection method for motor control according to claim 1, characterized in that: The speed equivalent value is introduced into the speed closed-loop control as a feedback item, and the speed closed-loop output value ctrl_out is: ctrl_out=kp×delta_speed(n)+ki×(delta_speed(n)-delta_speed(n-1)), Among them, delta_speed(n) is the current speed difference, delta_speed(n-1) is the speed difference of the previous beat, kp is the speed closed loop proportional coefficient, ki is the speed closed loop integral coefficient, The current speed difference delta_speed(n) is: delta_speed(n)=speed_target–speed_feedback–speed_cur, Among them, speed_target is the target speed, speed_feedback is the feedback speed, and speed_cur is the speed equivalent value.

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