A Method for Current Sharing and Thermal Equilibrium of the Driving Motors of a Deep-Sea Robot

Abstract

The present invention discloses a method for current sharing and thermal balance of a driving motor of a deep-sea robot, which includes the following steps: Step S1: Construct a differential equation set describing the input-output characteristics of the motor, covering both mechanical and electrical parts; Step S2: Measure the current and speed of each armature in real time and calculate the current difference; Step S3: Construct a parameter matrix and a solution matrix for calculating the control gain, and establish a weight matrix and an adjustment coefficient for dynamically calculating the control signal; Step S4: Update the control weight matrix in real time according to the current difference, iteratively update the solution matrix, calculate the control voltage signal and apply it to each armature; The current sharing and thermal balance method proposed by the present invention is based on the current signals of each armature of the motor, calculates the deviation signal and dynamically adjusts the control voltage, which not only ensures that the motor speed accurately tracks the target signal, but also ensures that the currents of each armature converge, thereby achieving thermal balance between the armatures and ensuring the stable operation of the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of deep - sea motor control, and more specifically, to a method for current sharing and thermal balance of a driving motor of a deep - sea robot. Background Art

[0002] As a key ocean operation tool, deep - sea robots are widely used in fields such as deep - sea exploration, resource development, and environmental monitoring. The deep - sea motor in them, as the core power unit, directly determines the overall performance of the deep - sea robot. Since the deep - sea motor needs to operate for a long time and at high intensity, a large amount of heat is easily generated. If the heat cannot be conducted and dissipated in a timely and effective manner, it will cause the motor to overheat, thereby reducing efficiency and even damaging the motor. The deep - sea environment has characteristics such as high water pressure, strong corrosiveness, and lack of natural convection, making it difficult to directly apply many traditional thermal management methods, and specific solutions need to be designed for these extreme conditions.

[0003] To optimize the heat dissipation efficiency of deep - sea motors, the heat dissipation can be achieved by optimizing the motor structure layout, key component materials, oil - circuit design, and impellers, etc. Among them, adopting a motor structure layout with multiple modular stators is an effective solution. This design divides the motor into multiple independent working areas, each partition is equipped with an independent stator, armature, and impeller, and the rotating shaft is driven by multiple armatures in cooperation. Through this layout of multiple modular stators, the motor is divided into multiple thermal management areas, and heat can be conducted and dispersed more efficiently within each area. In the motor design with multiple modular stators, by ensuring that the current of each armature converges under the overall load, the armatures can generate heat evenly, ensuring the thermal balance of the motor. Its core principle is to precisely control the drive voltage of the armatures of each motor segment so that the current and heat generation of each armature are consistent, thereby avoiding uneven heat generation caused by local overload and ensuring a stable temperature distribution while the motor operates efficiently. Although the design of a deep - sea robot driving motor with multiple modular stators has been proposed, the corresponding research and application of current sharing and thermal balance are still in the exploratory stage. In particular, there is still a lack of a systematic technical solution on how to coordinate the current of each partition armature to keep the motor with a uniform thermal distribution under the overall load.

[0004] Therefore, it is necessary to propose a method for current sharing and thermal balance applicable to the driving motor of a deep - sea robot with multiple modular stators to ensure that the motor can maintain a uniform and stable temperature distribution under different working conditions, thereby improving the working efficiency and reliability of the deep - sea robot motor system. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above - mentioned prior art and provide a method for current sharing and thermal balance of a driving motor of a deep - sea robot.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A method for current sharing and thermal balance of a driving motor of a deep - sea robot, comprising the following steps:

[0008] Step S1, considering a DC motor with n modular stators, constructing a differential equation set describing the input - output characteristics of the motor, covering both the mechanical part and the electrical part, for comprehensively describing the dynamic behavior of the motor;

[0009] Step S2, measuring the current values of each armature and the motor speed in real - time, and calculating the standard deviation of the current and the current difference between each armature;

[0010] Step S3, constructing a parameter matrix for calculating the control gain and a solution matrix for calculating the control signal, constructing a control weight matrix and a weight adjustment coefficient for dynamically calculating the control signal;

[0011] Step S4, according to the calculated standard deviation and current difference, updating the control weight matrix in real - time at a certain period, iteratively updating the solution matrix, calculating the control voltage signal and applying it to each armature.

[0012] Further, the step S1 includes the following steps:

[0013] Step S101, constructing variables and parameters for describing the dynamic characteristics of the motor. The variable represents the motor output, the variable represents the induced current of the j - th armature, the variable represents the control voltage signal input to the j - th armature, the parameter is the resistance of the j - th armature, the parameter is the inductance of the j - th armature, the parameter is the viscous friction coefficient of the motor, the parameter is the armature constant of the j - th armature, is the electromotive force constant of the j - th armature. For the j - th armature, j = 1, 2, …, n;

[0014] Step S102, constructing the mechanical part of the motor equation. According to the fact that the product of the motor inertial load J and the derivative of the rotational speed angular velocity is equal to the sum of all torques on the motor shaft, the following equation is obtained:

[0015] (1)

[0016] In formula (1), is the derivative operator, indicating the derivative of a certain variable with respect to time t;

[0017] Step S103, constructing the electrical part of the motor equation. According to the relationship between the applied voltage, induced electromotive force, resistance voltage and inductance voltage of each armature, the following equation is obtained:

[0018] (2)

[0019] In Equation (2), is the induced electromotive force of the j-th armature;

[0020] Step S104: Construct a system of differential equations describing the behavior of the motor. Based on Equation (1) and Equation (2), the differential equations describing the behavior of the motor can be obtained:

[0021] (3)

[0022] In Equation (3), the first row of the system of equations is used to describe the relationship between the applied voltage and the induced current , and the second row of the system of equations is used to describe the relationship between the induced current and the angular velocity of the motor shaft.

[0023] Furthermore, the said Step S2 includes the following steps:

[0024] Step S201: Measure the current values of each armature in the motor , (j = 1, 2,..., n) and the motor speed ;

[0025] Step S202: Calculate the mean value of the current of each armature;

[0026] Step S203: Calculate the standard deviation of the current of each armature. The symbol represents the absolute value;

[0027] Step S204: Calculate the difference between the currents of each armature, k = 1, 2,..., n, .

[0028] Furthermore, the said Step S3 includes the following steps:

[0029] Step S301: Construct the parameter matrices , and required for calculating the control gain.

[0030] , , ,

[0031] , , , ,

[0032] , , where diag(V) represents generating a diagonal matrix with vector V as the diagonal elements, represents the transpose operation of a matrix or vector;

[0033] Step S302, construct an iterative solution matrix for calculating the control signal, and construct a real iterative solution matrix of dimension and assign an initial value to make it positive definite or semi - positive definite;

[0034] Step S303, construct a control weight matrix , and construct a real positive definite matrix of dimension and assign an initial value , where represents an identity matrix of dimension;

[0035] Step S304, construct a weight adjustment coefficient , and construct a positive real number and assign a value.

[0036] Furthermore, the said Step S4 includes the following steps:

[0037] Step S401, calculate the current deviation matrix ,

[0038] (4)

[0039] Step S402, update the value of the control weight matrix at a certain period, and update it to ;

[0040] Step S403, when the value of the control weight matrix is updated, perform iterative calculation, and update the value of the iterative solution matrix according to Equation (5),

[0041] (5)

[0042] In Equation (5), represents the value of the solution matrix after the k - th iteration;

[0043] Step S404, after each iterative calculation, calculate the difference between and to check the convergence condition

[0044] (6)

[0045] If the convergence condition in Equation (6) is not satisfied, return to step S403 and continue the iteration. If the convergence condition is satisfied, stop the iteration and output . In Equation (6), is a preset small positive number used to determine whether the solution converges. The symbol represents the matrix norm;

[0046] Step S405, calculate the control signal according to Equation (7)

[0047] (7)

[0048] where , , is the set target signal of the motor speed;

[0049] Step S406, drive each armature with the voltage signal calculated according to Equation (7), and return to step S401.

[0050] The beneficial effects of the present invention are:

[0051] By real-time monitoring of the current signals of each armature in the drive motor of the deep-sea robot, calculating their deviation signals and dynamically updating the control voltage signal, the present invention not only ensures that the motor speed accurately tracks the target signal, but also guarantees that the currents of each armature tend to be consistent in the case of deviations in the parameters of each armature, thereby achieving thermal balance between the armatures and ensuring the stable operation of the motor. Description of the Drawings

[0052] Figure 1 is a schematic diagram of a control structure for the current sharing and thermal balance method of the drive motor of the deep-sea robot in this embodiment;

[0053] Figure 2 is a flowchart of a current sharing and thermal balance method for the drive motor of the deep-sea robot in this embodiment;

[0054] Figure 3 is an effect diagram of a current sharing and thermal balance method for the drive motor of the deep-sea robot in this embodiment. Detailed Embodiments

[0055] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0056] Embodiment: A method for achieving current sharing and thermal balance of a driving motor of a deep - sea robot. Based on real - time detection of the armature current in each partition and calculation of its mean value and deviation, the control weight matrix is dynamically adjusted and the control voltage is updated accordingly, so that the armature currents converge, thereby achieving current sharing and thermal balance of each armature. Figure 1 The process of implementing thermal balance control is as follows: For the driving motor of a deep - sea robot with multiple modular stators, first, complete the sensor configuration. Independently configure high - precision current sensors for each partition to collect phase - current signals in real - time, and use an encoder to accurately measure the motor speed signal. All sensing data is synchronously transmitted to a high - performance workstation. Then, the workstation realizes the real - time calculation of the control voltage signal. The workstation calculates the current difference in real - time based on the current sensing data, combines the dynamically updated weight matrix and the speed - tracking target, and calculates the control voltage signal according to the steps S1 - S4. Finally, the workstation applies the calculated control voltage signal to the motor through the motor driver. As Figure 1 、 Figure 2 shown, the real - time calculation of the control voltage signal specifically includes the following steps:

[0057] Step S1, considering a DC motor with n modular stators, construct a differential equation system that describes the input - output characteristics of the motor, covering both the mechanical part and the electrical part, to comprehensively describe the dynamic behavior of the motor.

[0058] Specifically, step S1 includes the following steps:

[0059] Step S101, construct the variables and parameters that describe the dynamic characteristics of the motor. The variable represents the output of the motor, that is, the angular velocity of the rotating shaft. The variable represents the induced current of the j - th armature. The variable represents the control voltage signal (input control signal) applied to the j - th armature. The parameter is the resistance of the j - th armature. The parameter is the inductance of the j - th armature. The parameter is the viscous friction coefficient of the motor, representing the proportional relationship between the frictional force on the rotating shaft and the angular velocity of the rotating shaft. The parameter is the armature constant of the j - th armature, representing the proportional relationship between the torque and the induced current by the applied voltage . The parameter is the electromotive - force constant of the j - th armature, representing the proportional relationship between its induced electromotive force and the angular velocity of the rotating shaft. For the j - th armature, j = 1, 2, …, n;

[0060] Step S102, construct the mechanical part of the motor equation. According to the fact that the product of the motor inertia load J and the derivative of the rotational angular velocity is equal to the sum of all torques on the motor shaft, the following equation is obtained:

[0061] (1)

[0062] In formula (1), is a derivative operator, indicating the derivative of a certain variable with respect to time t;

[0063] Step S103: Construct the electrical part of the motor equation. According to the relationship between the applied voltage, induced electromotive force, resistance voltage, and inductance voltage of each armature, the following equation is obtained:

[0064] (2)

[0065] In formula (2), is the induced electromotive force of the j-th armature;

[0066] Step S104: Construct a differential equation set to describe the behavior of the motor. Based on formula (1) and formula (2), a differential equation to describe the behavior of the motor can be obtained:

[0067] (3)

[0068] In formula (3), the first row of the equation set is used to describe the relationship between the applied voltage and the induced current , and the second row of the equation set is used to describe the relationship between the induced current and the angular velocity of the motor shaft.

[0069] Step S2: Measure the current value of each armature and the motor speed in real time, and calculate the standard deviation of the current and the current difference between each armature;

[0070] Specifically, step S2 includes the following steps:

[0071] Step S201: Measure the current value of each armature in the motor , (j = 1, 2,..., n) and the motor speed ;

[0072] Step S202: Calculate the average value of the current of each armature;

[0073] Step S203: Calculate the standard deviation of the current of each armature. The symbol represents the absolute value;

[0074] Step S204: Calculate the difference between the currents of each armature, k = 1, 2,..., n, .

[0075] Step S3, construct the parameter matrix required for calculating the control gain and the solution matrix for calculating the control signal, and construct the control weight matrix and the weight adjustment coefficient for dynamically calculating the control signal;

[0076] Specifically, in step S301, construct the parameter matrix required for calculating the control gain 、 and ,

[0077] , , ,

[0078] , , , ,

[0079] , , where diag(V) represents generating a diagonal matrix with vector V as the diagonal elements, represents the transpose operation of a matrix or vector;

[0080] Step S302, construct the iterative solution matrix for calculating the control signal, and construct -dimensional real iterative solution matrix and assign an initial value to make it positive definite or semi-positive definite (for example, assign the initial value as the zero matrix or the identity matrix);

[0081] Step S303, construct the control weight matrix , and construct -dimensional real positive definite matrix and assign an initial value (for example ), where represents -dimensional identity matrix;

[0082] Step S304, construct the weight adjustment coefficient , and construct a positive real number and assign a value (for example ), where increasing the value of the adjustment weight coefficient can accelerate the convergence speed of each armature current, but too high a weight coefficient may cause oscillations in the motor output. On the contrary, reducing the weight coefficient can slow down the convergence speed and improve the stability of the system at the same time.

[0083] Step S4, according to the calculated standard deviation and current difference, update the control weight matrix in real time at a certain period, iteratively update the solution matrix, calculate the control voltage signal and apply it to each armature;

[0084] Specifically, step S4 includes the following steps:

[0085] Step S401: Calculate the current deviation matrix at a certain period (e.g., 0.1 s). ,

[0086] (4)

[0087] In formula (4), the diagonal elements of the matrix are the standard deviations obtained in step S203 arranged in order, and the non - diagonal element in the j - th row and k - th column of the matrix is the current difference obtained in step S204 ;

[0088] Step S402: Update the control weight matrix at a certain period (e.g., 0.1 s), that is, update the value of to ;

[0089] Step S403: When the value of the control weight matrix is updated, perform iterative calculation and update the value of the iterative solution matrix according to formula (5),

[0090] (5)

[0091] In formula (5), represents the value of the solution matrix after the k - th iteration;

[0092] Step S404: After each iterative calculation, calculate the difference between and to check the convergence condition

[0093] (6)

[0094] If the convergence condition in formula (6) is not satisfied, return to step S403 and continue the iteration. If the convergence condition is satisfied, stop the iteration and output . In formula (6), is a preset very small positive number (e.g., ), used to judge whether the solution converges, and the symbol represents the matrix norm;

[0095] Step S405: Calculate the control signal according to formula (7)

[0096] (7)

[0097] Among them, , , is the set target signal of the motor speed;

[0098] Step S406, drive each armature according to the voltage signal calculated in Equation (7) and return to Step S401.

[0099] In this embodiment, the implementation structure of the current sharing and thermal balance method for the drive motor of the deep-sea robot with multiple modular stators is as Figure 1 shown. Among them, the current of each armature is collected in real time through a current sensor, and the speed of the motor shaft is obtained through an encoder. These current and speed signals are sent to a high-performance workstation. As the center of data processing and control, the high-performance workstation calculates the control signal according to the methods in Steps S1 - S4 and sends it to the driver. The driver applies voltage according to this signal to control the operation of the motor.

[0100] In this embodiment, the drive motor of the deep-sea robot with multiple modular stators includes three partitions, and each partition is equipped with an armature. Let the parameters of each armature in Equation (3) be as follows: , , , , , , , , , , , . Let the target signal that the motor speed needs to track be:

[0101] .

[0102] Detect the current and speed signals according to Steps S1 - S4 described in this embodiment, calculate the current deviation, generate the control signal and act on the motor, and obtain the current sharing and thermal balance effect of the motor as Figure 3 shown. Among them, in the time period of 0 - 15 seconds, the method of updating the control weight matrix according to the current deviation in Steps S401 and S402 is not adopted (partially using the method of this embodiment). At this time, the motor does not consider the current sharing and thermal balance during the process of tracking the target speed. The result shows that the motor can track the target speed, but the current deviation of Armatures 1 - 3 is large. Since 15 seconds, the current sharing method has been adopted (executed according to Steps S1 - S4 of this embodiment). At this time, the motor not only accurately tracks the target speed, but also the currents of Armatures 1 - 3 quickly converge. At 30 seconds, when the target signal changes, the motor speed can still respond quickly and track, and at the same time, the currents of Armatures 1 - 3 also quickly tend to be consistent after a short oscillation.

[0103] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the concept of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A method for current sharing and thermal balance of a driving motor of a deep-sea robot, characterized in that, It includes the following steps: Step S1: Consider a DC motor with n modular stators, and construct a differential equation set describing the input-output characteristics of the motor, covering the mechanical part and the electrical part, for comprehensively describing the dynamic behavior of the motor; Step S2: Measure the current values of each armature and the motor speed in real time, and calculate the standard deviation of the current and the current difference between each armature; Step S3: Construct a parameter matrix required for calculating the control gain and a solution matrix for calculating the control signal, and construct a control weight matrix and a weight adjustment coefficient for dynamically calculating the control signal; Step S4: According to the calculated standard deviation and current difference, based on the weight adjustment coefficient defined in Step S3, update the control weight matrix in real time at a certain period, substitute the updated control weight matrix and the parameter matrix generated in Step S3 into Equation (5) for iterative calculation of the solution matrix, and generate a control voltage signal in real time based on the latest solution matrix and act on each armature, so that the armature currents converge, thereby realizing the equal-current thermal balance of each armature; (5) In formula (5), represents the value of the solution matrix after the k-th iteration is completed; , and are parameter matrices required for constructing the calculation control gain, is the control weight matrix, represents the transpose operation of a matrix or vector.

2. A method for current sharing and thermal balance of a driving motor of a deep-sea robot according to claim 1, characterized in that The said Step S1 includes the following steps: Step S101, construct variables and parameters describing the dynamic characteristics of the motor. The variable represents the output speed of the motor. The variable represents the induced current of the j-th armature. The variable represents the control voltage signal input to the j-th armature. The parameter is the resistance of the j-th armature. The parameter is the inductance of the j-th armature. The parameter is the viscous friction coefficient of the motor. The parameter is the armature constant of the j-th armature. is the electromotive force constant of the j-th armature. For the j-th armature, j = 1, 2, …, n; Step S102: Construct the mechanical part of the motor equation. According to the fact that the product of the motor inertia load J and the derivative of the motor output speed is equal to the sum of all torques on the motor shaft, the following equation is obtained: (1) In formula (1), is a derivative operator, indicating the derivative of a certain variable with respect to time t; Step S103: Construct the electrical part of the motor equation. According to the relationship between the applied voltage, induced electromotive force, resistance voltage, and inductance voltage of each armature, the following equation is obtained: (2) In Equation (2), is the induced electromotive force of the j-th armature; Step S104: Construct a differential equation set describing the motor behavior. Based on Equation (1) and Equation (2), a differential equation describing the motor behavior is obtained: (3) In Equation (3), the first row of the system of equations is used to describe the relationship between the applied voltage and the induced current while the second row of the system of equations is used to describe the relationship between the induced current and the output rotational speed of the motor .

3. A method for current sharing and thermal balance of a driving motor of a deep-sea robot according to claim 1, characterized in that, The said Step S2 includes the following steps: Step S201, measure the current values of each armature in the motor in real time , (j = 1, 2, …, n) and the output speed of the motor ; Step S202, calculate the mean value of the current of each armature ; Step S203, calculate the standard deviation of the current of each armature , the symbol represents the absolute value; Step S204, calculate the difference between each armature current , where k = 1, 2, …, n, .

4. A method for current sharing and thermal balance of a driving motor of a deep-sea robot according to claim 1, characterized in that, The said Step S3 includes the following steps: Step S301, construct the parameter matrix required for calculating the control gain , and , ， ， ， ， ， ， ， , , where diag(V) represents generating a diagonal matrix with vector V as the diagonal elements, represents the transpose operation of a matrix or vector; and represent the resistances of armature 1 and armature n respectively, and represent the inductances of armature 1 and armature n respectively, and represent the electromotive force constants of armature 1 and armature n respectively, and represent the armature constants of armature 1 and armature n respectively, represents the inertial load of the motor, represents the viscous friction coefficient of the motor, represents the total number of modular stators of the motor, i.e., the total number of armatures; Step S302, construct an iterative solution matrix for calculating the control signal, and construct a real iterative solution matrix of dimensions and assign an initial value to make it positive definite or semi-positive definite; Step S303, construct a control weight matrix , construct a real positive definite matrix of dimension and assign an initial value , where represents the identity matrix of dimension Step S304, construct a weight adjustment coefficient , construct a positive real number and assign a value.

5. A method for current sharing and thermal balance of a driving motor of a deep-sea robot according to claim 1, characterized in that, The said Step S4 includes the following steps: Step S401, calculate the current deviation matrix at a certain period , (4) Among them, , , respectively represent the standard deviations of the currents of armature 1, armature j, and armature n, represents the difference between the currents of armature j and armature k; Step S402: Update the control weight matrix at a set period with its value updated to ; where is the constructed weight adjustment coefficient Step S403, when the value of the control weight matrix is updated, iterative calculation is performed, and the value of the iterative solution matrix is updated according to Equation (5); Step S404, after each iterative calculation, calculate and the difference between them, and check the convergence condition (6) If the convergence condition in Equation (6) is not satisfied, return to step S403 and continue the iteration. If the convergence condition is satisfied, stop the iteration and output , in Equation (6), is a preset small positive number used to determine whether the solution converges. The symbol represents the matrix norm; Step S405: Calculate the control signal according to Equation (7) (7) Among them, , , is the set target signal of the motor speed; is the output speed of the motor, , are the induced currents of armature 1 and armature n respectively; Step S406, drive each armature with the voltage signal calculated according to Equation (7), and return to Step S401. ​

Images