A lateral thruster load protection system and control method

Abstract

This invention discloses a lateral thruster load protection system, including a thrust motor current detection module, a thrust motor overload judgment module, and a load protection module. It also discloses its control method, which involves real-time detection of the thrust motor current using a current sensor, calibrating and calculating the current signal, and determining whether an overload has occurred by calculating the deviation from the thrust motor's rated value. If an overload is detected, a compliant protection mode is activated. This invention provides advantages such as timely load protection, stable pitch control, high control accuracy, and strong anti-interference capabilities for controlling the lateral thruster.

Description

Technical Field

[0001] This invention belongs to the field of marine propulsion system technology, specifically relating to a lateral thruster load protection system and control method. Background Technology

[0002] With the increasing demands for maneuverability of ships and marine engineering platforms, lateral thrusters are widely used in cargo ships, engineering vessels, oil tankers, and special-purpose work platforms. Lateral thrusters provide lateral thrust as needed, improving the ship's lateral maneuverability.

[0003] Adjustable-pitch lateral thrusters are driven by a constant-speed motor. The blade angle is controlled by regulating the flow direction and flow rate of hydraulic oil through the hub cylinder, allowing for adjustable thrust direction and magnitude in constant-speed mode. Due to the influence of pitch and external water flow, the load on the propulsion motor is constantly changing. Excessive load or prolonged overload operation of the propulsion motor can lead to damage and affect the safety of the vessel.

[0004] Common adjustable pitch lateral thrusters use a method of reducing the pitch for load protection. This control method reduces the thrust of the lateral thruster, resulting in low efficiency. At the same time, it cannot avoid overload caused by external water flow, which can lead to overload of the drive motor. Summary of the Invention

[0005] One of the objectives of this invention is to improve the efficiency of lateral thrusters, provide protection for the propulsion motor throughout the entire process, and prevent the propulsion motor from operating under overload conditions for a long time, thus providing a lateral thruster load protection system.

[0006] The technical solution adopted by this invention to solve its technical problem is: a lateral thruster load protection system, comprising: a thrust motor current detection module, used to calculate the real-time current of the thrust motor through three current sensors respectively installed on the U, V, and W phase lines of the three-phase asynchronous motor; a thrust motor overload judgment module, used to calculate the deviation between the real-time current feedback value of the thrust motor and the rated current setting value; and a load protection module, used to judge the overload state of the thrust motor based on the deviation and enter the load protection mode.

[0007] The second objective of this invention is to provide a control method for the aforementioned lateral thruster load protection system, comprising the following steps:

[0008] (1) Propulsion motor current sampling and processing: Real-time current signals are collected by three Hall sensors on the main circuit of the propulsion motor. The signals of each Hall sensor are filtered and equalized and then processed to calculate the real-time current of the propulsion motor.

[0009] (2) The thrust motor overload judgment module calculates the difference between the real-time current fed back by the propulsion motor and the rated current setting value. If the deviation is greater than 0 and the overload time exceeds 1 second, the propulsion motor is judged to be overloaded, and the load protection module is activated to enter the load protection mode.

[0010] (3) The load protection module protects the propulsion motor: it blocks the handle control command, and the pitch control command is automatically reduced or increased according to the set speed until the propulsion motor is no longer overloaded. It maintains the current pitch, and if the propulsion motor is not overloaded within a stable time, it slowly increases the pitch control command until the handle control command is reached.

[0011] During the execution of the load protection function, when the absolute value of the pitch control command is detected to be greater than the absolute value of the handle control command, the protection mode is exited and the action follows the handle control command; when the pitch control command is detected to be continuously decreasing, but the propulsion motor is still overloaded, the minimum set pitch control command is maintained.

[0012] The control method for the lateral thruster load protection system involves averaging the real-time current over 10 sampling periods, taking the median value from every 100 averages, and then averaging the current values ​​of the three channels again.

[0013] The advantages and positive effects of this invention are as follows:

[0014] 1. The present invention obtains the propulsion motor current signal by collecting three currents through the thrust motor current detection module, filtering and taking the median value, thereby reducing current signal sampling interference and ensuring the accuracy of the current.

[0015] 2. The present invention uses a thrust motor overload judgment module to perform a delay processing on the overload judgment to avoid false judgments.

[0016] 3. Due to external factors such as ocean currents, side-propulsion motors are highly susceptible to overload, and prolonged overload can lead to motor burnout. This invention can adjust the pitch according to the propulsion motor current to reduce the motor load. To minimize pitch fluctuations, a strategy of rapidly reducing the pitch and slowly restoring it is employed to further protect the propulsion motor.

[0017] 4. To ensure the maneuverability of the vessel, the present invention sets a minimum pitch for load protection to prevent zero thrust from the lateral thrusters due to overload. Simultaneously, during load protection, the handle can be operated in the direction of low thrust, preventing loss of control during vessel maneuvering.

[0018] 5. The present invention has good adaptability and can change the control parameters to achieve different responses according to actual needs. Attached Figure Description

[0019] Figure 1 This is a functional flowchart of the load protection system of the present invention;

[0020] Figure 2 The current curve of the motor. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and the following embodiments.

[0022] Example 1

[0023] This invention discloses a lateral thruster load protection system, comprising:

[0024] The thrust motor current detection module is used to calculate the real-time current of the propulsion motor by means of three current sensors respectively set on the U, V and W phase lines of the three-phase asynchronous motor.

[0025] The thrust motor overload detection module is used to determine the overload status of the propulsion motor. By calculating the deviation between the real-time current feedback value of the propulsion motor and the rated current setting value, it determines whether the propulsion motor is overloaded. If it is overloaded, it enters the load protection mode.

[0026] Example 2

[0027] The present invention discloses a control method for a lateral thruster load protection system, comprising the following steps:

[0028] (1) Propulsion motor current sampling and processing: Real-time current signals are collected by three Hall sensors on the main circuit of the propulsion motor. The signals of each Hall sensor are filtered and equalized and then processed to calculate the real-time current of the propulsion motor. The average value is taken every 10 sampling cycles, and the median value is taken based on every 100 average values. The average value of the current values ​​of the three channels is taken again.

[0029] (2) The thrust motor overload judgment module calculates the difference between the real-time current fed back by the propulsion motor and the rated current setting value. If the deviation is greater than 0 and the overload time exceeds 1 second, the propulsion motor is judged to be overloaded, and the load protection module is started to enter the load protection mode.

[0030] (3) The load protection module protects the propulsion motor: it blocks the handle control command, and automatically decreases or increases the pitch control command according to the set speed until the propulsion motor is no longer overloaded. It maintains the current pitch, and if the propulsion motor is not overloaded within a stable time, it slowly increases the pitch control command until the handle control command is reached.

[0031] During the execution of the load protection function, when the absolute value of the pitch control command is detected to be greater than the absolute value of the handle control command, the protection mode is exited and the action follows the handle control command; when the pitch control command is detected to be continuously decreasing, but the propulsion motor is still overloaded, the minimum set pitch control command is maintained.

[0032] Depending on the ship type and application requirements, the control model parameters can be set, including: propulsion motor rated current, load protection pitch reduction speed, load protection pitch increase speed, and load protection minimum pitch setting value.

[0033] Example 3

[0034] A multi-purpose workboat is equipped with bow and stern side thrusters, both of which are adjustable pitch type. The bow thruster uses a 700KW type III asynchronous motor with a rated speed of 1500r / min and a rated current of 1050A. The design still water lateral speed is 6kn. The side thruster blade diameter is 1200mm, the wake coefficient is 0.246, the slip efficiency is 0.891, the maximum pitch on the port side is 50°, and the maximum pitch on the starboard side is 50°.

[0035] 1. Hall effect sensors are installed on the U-phase, V-phase, and W-phase of the main circuit of the three-phase asynchronous motor. The sensor range is 0-2000A. The average value is taken for 10 sampling periods of each sensor, and then the median value is taken from every 100 average values. The processed values ​​of the three sensors are averaged to calculate the real-time current of the propulsion motor.

[0036] 2. According to Figure 1 The model programming software sets the rated current of the propulsion motor to 1050 * 0.98 = 1029A based on the motor parameters. When the load protection function is activated, the pitch reduction speed is 0.001. The controller's task execution cycle is 100µs, therefore the pitch command decreases by 10° per second, and the solenoid valve remains open to reduce the pitch; when the propulsion motor current drops below the rated current, the pitch command increases by 0.00001 per sweep cycle, that is, increases by 1° per second.

[0037] See propulsion motor current Figure 2 Based on the observations during the operation of this lateral thruster, the propulsion motor current consistently fluctuated around the rated current, and the propulsion motor did not experience prolonged overload, indicating good application performance.

[0038] The control method of the present invention has been applied on actual ships and the feedback control effect is good.

[0039] The above embodiments are merely examples and illustrations of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A control method for a side thruster load protection system, characterized in that, The protection system comprises a thrust motor current detection module for calculating real-time current of the propulsion motor through current sensors on U, V and W phase lines of the three-phase asynchronous motor, a thrust motor overload judgment module for calculating deviation of real-time current feedback value of the propulsion motor from rated current set value, and a load protection module for judging overload state of the propulsion motor according to the deviation and entering a load protection mode. (1) propulsion motor current sampling processing: real-time current signals are collected through three Hall sensors on a main circuit of the propulsion motor, signals of each Hall sensor are filtered and equalized for reprocessing, and real-time current of the propulsion motor is calculated; (2) the thrust motor overload judgment module calculates difference between the real-time current of the propulsion motor and the rated current set value, and judges that the propulsion motor is overloaded when the deviation is greater than 0 and overload time exceeds 1S, and starts the load protection module; (3) the load protection module shields handle control instructions, decreases or increases pitch control instructions according to set speed until the propulsion motor is no longer overloaded, maintains current pitch, slowly increases the pitch control instructions until the handle control instructions are reached; when it is detected that an absolute value of the pitch control instructions is greater than an absolute value of the handle control instructions, the protection mode is exited and the handle control instructions are followed; when it is detected that the pitch control instructions are continuously decreased but the propulsion motor is still overloaded, the minimum set pitch control instructions are maintained.

2. A control method of a side thruster load protection system according to claim 1, characterized in that, The real-time current is an average value of every 10 sampling periods, median values are processed on the basis of every 100 average values, and the current values of the three channels are averaged again.

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