Immersed brushless direct current motor suitable for full-sea-depth closed-loop operation

Abstract

The invention discloses an immersion brushless direct current motor suitable for full sea depth closed loop operation, the motor comprises an end cover, a rotor assembly, a stator assembly, an outer shell, a magnetic encoder and a motor driver assembly, the rotor assembly is arranged between the stator assembly and the outer shell, one end of the rotor assembly is connected with the end cover, the other end of the rotor assembly is connected with the stator assembly, and the magnetic encoder is connected with the motor driver assembly. The stator assembly is in a colloid potting sealing mode, and the magnetic encoder and the motor driver assembly are arranged in a cavity in the rear portion of the stator assembly and are in a colloid potting sealing mode. According to the invention, through the integrated potting stator assembly, the magnetic encoder and the motor driver assembly, waterproof and pressure-resistant processing can be carried out more conveniently, the size of the motor can be reduced more conveniently, the motor is more suitable for full-sea-depth closed-loop operation, and the problems of high manufacturing cost and complex and heavy equipment of a traditional motor are solved.

Description

Technical Field

[0001] The present invention relates to the field of deep-sea power tools, and in particular to a submerged brushless DC motor suitable for closed-loop operation at full sea depth. Background Art

[0002] The full-sea-depth motor is one of the important research and development directions of my country's deep-sea exploration technology. It is designed to cope with the extreme conditions of the deep-sea environment. The deep-sea environment has high pressure, low temperature and strong corrosion, which puts extremely high requirements on the pressure resistance, sealing and corrosion resistance of the motor. At present, the common full-sea-depth motor is oil-filled compensation type, which requires a heavy metal shell and oil compensation device, complicated equipment and low power density. For example, Chinese patent publication number CN108418370A discloses a DC motor power device that can be used to measure liquid viscosity under high pressure conditions, including an integral pressure-resistant shell, a permanent magnet brushless DC motor power mechanism and a forced rotation actuator; and Chinese patent publication number CN102832749A discloses an oil-filled pressure-compensated deep-sea motor and a manufacturing method thereof, wherein a pressure compensator provided with a piston is connected to the tail end of the permanent magnet brushless DC motor, and the inner cavities of the permanent magnet brushless DC motor and the pressure compensator are interconnected, and at the same time, the deformation resistance of the end shell of the pressure compensator close to the piston end face is made smaller than the deformation resistance of the permanent magnet brushless DC motor shell, and then the inner cavities of the permanent magnet brushless DC motor and the pressure compensator are filled with insulating hydraulic oil.

[0003] As an underwater power unit, it is necessary to accurately control the motor to output a specified speed, torque and angle underwater, and feed back its position and speed to the controller to achieve closed-loop control. The current common technology is to place the sensor at the rear of the motor and seal it for pressure resistance, but this increases the motor manufacturing cost and manufacturing process, and reduces system reliability. For example, the publication number CN110829740A discloses a submerged integrated permanent magnet synchronous motor, which is powered by a drive controller to drive the external connection mechanism to rotate at a certain speed, and uses a Hall sensor assembly to achieve closed-loop control of the motor position and speed; the invention places the driver in the control section, achieves waterproofing through a mechanical structure, and is protected by a pressure-resistant shell.

[0004] In speed and torque control applications, the motor driver receives control instructions and adjusts the motor speed according to these instructions. At the same time, the actual speed of the motor is monitored in real time and compared with the target speed, and any deviation is eliminated by adjusting the current. Traditional deep-sea motor control drivers are often placed in a waterproof and pressure-resistant chamber together with sensors to achieve waterproof and pressure-resistant effects, which increases the complexity of the system. Motor drivers generate heat during operation, especially in high-voltage and high-current applications. Improper thermal management may cause device performance degradation or even damage. Summary of the invention

[0005] The purpose of the present invention is to provide a submersible brushless DC motor suitable for closed-loop operation at full sea depth. Through the integrated potting stator assembly, magnetic encoder and motor driver assembly, it is more convenient to perform waterproof and pressure-resistant treatment and reduce the size of the motor, making it more suitable for closed-loop operation at full sea depth, and solving the problems of high manufacturing cost and complex and bulky equipment of traditional motors.

[0006] The present invention solves the above technical problems by the following technical solutions:

[0007] A submerged brushless DC motor suitable for closed-loop operation at full sea depth, the motor comprising an end cover, a rotor assembly, a stator assembly, an outer shell, and a magnetic encoder and a motor driver assembly. The rotor assembly is arranged between the stator assembly and the outer shell, one end of which is connected to the end cover, and the other end of which is connected to the stator assembly. The stator assembly is in a colloid potting and sealing form, and the magnetic encoder and the motor driver assembly are arranged in a cavity at the rear of the stator assembly and are in a colloid potting and sealing form.

[0008] The submersible brushless DC motor provided by the present invention is in a completely water-permeable form, and all components are immersed in seawater for operation.

[0009] The rotor assembly includes a rotor shaft, a rotor yoke, a rotor magnetic steel, a special magnetic steel for a magnetic encoder and two stainless steel bearings. The rotor shaft and the rotor yoke are connected by an interference fit. The rotor magnetic steel is bonded to the rotor yoke at equal intervals along the inner surface of the rotor yoke. The special magnetic steel for the magnetic encoder is assembled in a groove at the end of the rotor shaft. The inner holes of the two stainless steel bearings are interference fit with the end of the rotor shaft and are positioned by the shaft shoulder of the rotor shaft.

[0010] The rotor magnets are coaxially installed, have the same magnetizing polarity and waveform, are made of 35UH NdFeB permanent magnets, and the rotor shaft is a solid shaft.

[0011] Preferably, the magnetic steel dedicated to the magnetic encoder is radially magnetized, and the material is 35UH neodymium iron boron permanent magnet.

[0012] The rotor yoke is provided with evenly distributed convex keys, and the rotor magnetic steel is positioned and centered by the convex keys.

[0013] Preferably, the stator assembly comprises a stator core, a stator winding, a potting colloid and an inner frame, the stator winding is wound on the stator core, the stator core and the inner frame are connected by interference fit, and the potting colloid used for sealing is formed by demolding the stator core, the stator winding and the inner frame through a mold to form a stator assembly as a whole.

[0014] Preferably, the stator core is a semi-closed flat-bottomed slot.

[0015] The magnetic encoder and the motor driver assembly are arranged in the cavity at the rear of the inner frame.

[0016] The magnetic encoder and motor driver assembly comprises a magnetic encoder, a copper column, a motor driver and a magnetic encoder bracket which are connected in sequence. The potting colloid wraps the magnetic encoder, the copper column, the motor driver and the magnetic encoder bracket and is arranged in a cavity at the rear of the stator assembly.

[0017] The motor driver supplies power and communicates to the stator assembly via a cable, and the magnetic encoder detects the rotation speed and position accuracy of the rotor assembly.

[0018] Preferably, the rotor magnets in the rotor assembly are 28, and the stator core in the stator assembly adopts a 14-slot structure.

[0019] The advantages of the present invention compared with the prior art are:

[0020] In view of the existing technology of full-sea-depth motors, traditional motors have the problems of high manufacturing cost, complex and bulky equipment, and difficulty in application in occasions requiring high performance and low cost. A submerged brushless DC motor suitable for full-sea-depth closed-loop operation is proposed, which has the following advantages:

[0021] The motor as a whole, including sensors and drive controllers, does not require a pressure-resistant casing at all: the built-in drive controller supplies power to the motor stator, which can drive actuators such as reducers to rotate at a specified speed or angle. The stator component of the motor is potted with a colloid to achieve waterproof and pressure-resistant effects, while also achieving excellent heat dissipation effects; a magnetic encoder and a motor driver component are used to achieve closed-loop control of the motor position and speed, solving the problems of large motor size, high cost, complex maintenance, and unfriendly environment caused by the use of pressure-resistant casings and oil-filled compensation in the prior art to achieve waterproof and pressure-resistant effects; by installing the magnetic encoder and motor driver components inside the motor and using colloid potting, waterproof and pressure-resistant treatment can be performed more conveniently and the motor size can be reduced, while having the advantages of low cost, reliable operation, high power density, and compact size. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the motor structure provided by the present invention;

[0023] Figure 2 A structural diagram of a rotor assembly provided by the present invention;

[0024] Figure 3 A cross-sectional view of a rotor assembly provided by the present invention;

[0025] Figure 4 A structural diagram of the stator core provided by the present invention;

[0026] Figure 5 A plan view of the magnetic encoder and motor driver assembly provided by the present invention;

[0027] Figure 6 A cross-sectional view of a magnetic encoder and a motor driver assembly provided by the present invention;

[0028] Figure 7 This is the appearance diagram of the reduction motor model DM400 of Dayang Intelligent Technology in Comparative Example 2. DETAILED DESCRIPTION

[0029] In view of the fact that traditional motors cannot meet the requirements of submersible type, small size, integration and high power density, the present invention has made structural improvements and provided a submersible brushless DC motor that can operate in a closed loop and is suitable for full sea depth, such as Figure 1 As shown, it specifically includes an end cover 1, a rotor assembly 2, an outer shell 3, a stator assembly 4, a magnetic encoder and a motor driver assembly 5. The rotor assembly 2 is arranged between the stator assembly 4 and the outer shell 3, one end of which is connected to the end cover 1, and the other end is connected to the stator assembly 4. The stator assembly 4 is in a colloid potting and sealing form. The magnetic encoder and the motor driver assembly 5 are arranged in a cavity at the rear of the stator assembly 4 and are in a colloid potting and sealing form.

[0030] The specific structure is:

[0031] The outer shell 3, the stator assembly 4 and the end cover 1 are centered through the stopper and fastened with bolts;

[0032] like Figure 2 and Figure 3 As shown, the rotor assembly 2 includes a rotor shaft 10, a rotor yoke 9, a rotor magnetic steel 8, a magnetic steel 6 for a magnetic encoder, a stainless steel bearing 7 and a stainless steel bearing 11; the rotor shaft 10 and the rotor yoke 9 are connected by interference fit and assisted by special glue bonding to output speed and torque and drive the external mechanism to rotate together, the rotor magnetic steel 8 for generating magnetic flux is bonded to the rotor yoke 9 at equal intervals along the inner surface of the rotor yoke 9, wherein the rotor yoke 9 uses evenly distributed convex keys to center and center the rotor magnetic steel 8, ensuring that the rotor magnetic steel 8 is equidistantly placed and bonded along the inner surface of the rotor yoke 9, and the gaps between the rotor magnetic steels 8 are uniform, and the special magnetic steel 6 for generating and detecting magnetic flux is assembled in the groove at the end of the rotor shaft 10, and the inner holes of the stainless steel bearings 7 and the stainless steel bearings 11 for supporting the rotor assembly 2 are interference fit with the end of the rotor shaft 10, and are positioned by the shaft shoulder of the rotor shaft 10.

[0033] In this embodiment, the rotor magnet 8 is coaxially installed, with the same magnetizing polarity and waveform, and is made of 35UH NdFeB permanent magnets. The permanent magnets have high residual magnetic density and coercive force, are magnetized in parallel, and are surface mounted. A stainless steel sleeve is added to the surface to suppress the thermal expansion of the magnet and ensure the safety and reliability of the magnet during long-term operation. The magnetic encoder-specific magnet 6 is radially magnetized, and is made of the same 35UH NdFeB permanent magnet.

[0034] In this embodiment, the rotor shaft 10 is a solid shaft, which enables the motor to output high torque at low speed and smoothly. Figure 4 As shown, the stator assembly 4 includes a potting colloid 12, a stator winding 13, a stator core 14 and an inner frame 15. The stator winding 13 is wound on the stator core 14. The stator core 14 and the inner frame 15 are connected by interference fit. The potting colloid 12 used for sealing is formed by potting the stator core 14, the stator winding 13 and the inner frame 15 in a mold and then demolding to form the stator assembly 4 as a whole.

[0035] In this embodiment, the stator core 14 is a semi-closed flat-bottomed slot, the slot has little effect on the magnetic field, and the flat bottom and yoke are relatively thick, which is beneficial to reducing the loss of the stator core 14.

[0036] In the rotor assembly 2, as Figure 2 and Figure 3 As shown, the number of rotor magnets 8 is 28, ensuring that the rotor assembly 2 is a 28-level structure. At the same time, the stator core 14 adopts a 14-slot structure, which reduces the cogging torque and eliminates the unbalanced magnetic pull.

[0037] The motor adopts a magnetic encoder 17 with small size, wide frequency response and easy installation to achieve high-precision, non-contact measurement of the motor speed and position, reducing the implementation cost of the system. The magnetic encoder and motor driver assembly 5 includes a magnetic encoder bracket 20, a magnetic encoder 17, a potting colloid 16, a motor driver 19, and a copper column 18. Figure 5 and Figure 6 As shown, the motor, magnetic encoder and motor driver assembly 5 are designed, assembled and potted in an integrated manner, and the potting colloid 16 wraps the magnetic encoder 17, the magnetic encoder bracket 20, the motor driver 19 and the copper column 18 to achieve waterproof and pressure resistance. Figure 5 and Figure 6As shown, the magnetic encoder and motor driver assembly 5 are placed in the gap at the rear of the inner frame 15, and due to electromagnetic shielding, the operation of the magnetic encoder 17 and the motor driver 19 is not affected by the operation of the motor. The product integration is improved, and the pressure resistance and corrosion resistance requirements of the underwater motor are met. At the same time, the heat dissipation conditions are greatly improved when the motor works in the seawater environment for a long time. The current density of the motor is higher than that of the conventional motor when the motor is running, which reduces the size of the motor and improves the power density; it meets the pressure resistance and corrosion resistance requirements of the underwater motor and improves the reliability of the motor's long-term operation. The motor is in the form of colloid potting and sealing, which effectively isolates the seawater and has good sealing reliability. At the same time, if the magnetic encoder and motor driver assembly 5 are damaged, the magnetic encoder and motor driver assembly can be replaced separately, which provides convenience for maintenance;

[0038] The specific connection method of the end cover 1, the rotor assembly 2, the outer shell 3, the stator assembly 4, and the encoder assembly 5 is:

[0039] The rotor assembly 2 is arranged between the stator assembly 4 and the outer shell 3 for generating a torque and driving the external connection mechanism to rotate together. The end cover 1 supporting one end of the rotor assembly 2 is heat-fitted into the inner hole of the front end surface of the outer shell 3, and the other end of the rotor assembly 2 is supported by a stainless steel bearing 7 placed in the stator assembly 3. A certain distance is left between the surface of the magnetic encoder and motor driver assembly 5 used to detect the speed and position accuracy of the rotor assembly 2 and the encoder-specific magnet 6 assembled at the end of the rotor assembly 2, and the magnetic encoder and motor driver assembly 5 are fixed in the rear cavity of the stator assembly 4 by bolts, and the stator assembly 4 is powered and communicated through cables, and the magnetic encoder and motor driver assembly 5 are used to detect the speed and position accuracy of the rotor assembly 2. The magnetic encoder and motor driver assembly 5 are fixed by bolts.

[0040] The dimensions of the submersible brushless DC motor provided in this embodiment are: motor length 50 mm, motor diameter 80 mm. The submersible brushless DC motor provided in this embodiment can operate at a full sea depth of 0-11000m.

[0041] The working process of the water-immersed brushless DC motor provided above is:

[0042] The motor is powered and driven by an external drive controller. The rotating magnetic field of the stator component 1 interacts with the air gap magnetic field generated by the rotor component 2 to generate torque, driving the rotor component 2 to rotate at the rated speed and torque. The rotor shaft 11 drives the external reducer and other connecting mechanisms through keys to output the speed and torque. The motor detects the position and speed of the rotor component 2 by using a magnetic encoder and a motor driver component 5. When the rotor component 2 rotates, the magnetic encoder and the motor driver component 5 detect the magnetic field changes of the encoder's dedicated magnet according to the Hall effect, and convert them into a sine wave. When the motor runs continuously, the rotation direction and position range of the motor rotor can be determined by the changing Hall signal state. The motor driver 19 realizes closed-loop control by providing three-phase current to the stator winding 13 and detecting the electrical signal of the magnetic encoder 17 in real time.

[0043] Comparative Example 1

[0044] The application publication number CN 110829740 A discloses a submerged integrated permanent magnet synchronous motor, which places a driver in a control section, is waterproofed by a mechanical structure, and is protected by a pressure-resistant casing, and can operate at a water depth of 500 m.

[0045] Compared with comparative example 1, the magnetic encoder 17 and the motor driver 19 provided by the present invention are placed in the potting colloid 16, and do not need the protection of the pressure-resistant shell, and can cooperate with the motor body to operate at full sea depth (0-11000m). In terms of size, the motor provided by the present invention can reduce the length by 50% compared with comparative example 1.

[0046] Comparative Example 2

[0047] The model of the reduction motor of Dayang Intelligent Technology is DM400, and the product dimensions are as follows Figure 7 shown.

[0048] The sea depth model (0-6000m) of the reduction motor of Example 2 is an oil-filled compensation type, which requires the motor to be filled with compensation hydraulic oil to achieve waterproof and pressure-resistant effects, and an external compensation oil tank is also required, and the equipment is highly complex. Under the condition that the torque and speed achieved are relatively consistent, the length of the motor provided by the present invention is only 20% of the reduction motor (the length of the motor provided by the present invention is 50mm, and the length of the reduction motor product is 275mm); the diameter is reduced by 10% (the diameter of the motor provided by the present invention is 80mm, and the diameter of the reduction motor product is 88mm).

[0049] In summary, the submerged brushless DC motor suitable for closed-loop operation at full sea depth provided by the present invention does not require any pressure-resistant casing protection at all, is driven by a built-in drive controller, drives the external connecting mechanism to rotate at a certain speed or angle, and adopts a magnetic encoder and a motor driver assembly to realize closed-loop control of the motor position and speed. The magnetic encoder and the motor driver assembly can be installed in the cavity at the rear of the motor stator assembly and are not subject to electromagnetic interference. With a good mechanical structure, they can effectively isolate seawater and can work in a full sea depth environment without a pressure-resistant casing. The motor, the magnetic encoder, and the motor controller realize integrated design, assembly, and testing, which improves the integration of the product, reduces the size of the motor, and has a high cost performance.

[0050] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A submersible brushless DC motor suitable for closed-loop operation at full sea depth, characterized in that: The motor includes an end cover, a rotor assembly, a stator assembly, an outer shell, and a magnetic encoder and a motor driver assembly. The rotor assembly is arranged between the stator assembly and the outer shell, one end of which is connected to the end cover, and the other end is connected to the stator assembly. The stator assembly is in a colloid potting and sealing form. The magnetic encoder and the motor driver assembly are arranged in a cavity at the rear of the stator assembly and are in a colloid potting and sealing form.

2. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 1 is characterized in that: The rotor assembly includes a rotor shaft, a rotor yoke, a rotor magnetic steel, a special magnetic steel for a magnetic encoder and two stainless steel bearings. The rotor shaft and the rotor yoke are connected by an interference fit. The rotor magnetic steel is bonded to the rotor yoke at equal intervals along the inner surface of the rotor yoke. The special magnetic steel for the magnetic encoder is assembled in a groove at the end of the rotor shaft. The inner holes of the two stainless steel bearings are interference fit with the end of the rotor shaft and are positioned by the shaft shoulder of the rotor shaft.

3. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 2 is characterized in that: The rotor magnet is coaxially installed, has the same magnetizing polarity and waveform, is made of 35UH NdFeB permanent magnet, and the rotor shaft is a solid shaft; the magnetic encoder special magnet is radially magnetized, and is made of 35UH NdFeB permanent magnet.

4. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 2 is characterized in that: The rotor yoke is provided with evenly distributed convex keys, and the rotor magnetic steel is positioned and centered by the convex keys.

5. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 1 is characterized in that: The stator assembly includes a stator core, a stator winding, a potting colloid and an inner frame. The stator winding is wound on the stator core. The stator core and the inner frame are connected by interference fit. The potting colloid used for sealing is used to seal the stator core, the stator winding and the inner frame through a mold and then demolded to form the stator assembly as a whole.

6. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 5 is characterized in that: The stator core is a semi-closed flat bottom slot.

7. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 5, characterized in that: The magnetic encoder and the motor driver assembly are arranged in the cavity at the rear of the inner frame.

8. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 1 is characterized in that: The magnetic encoder and motor driver assembly comprises a magnetic encoder, a copper column, a motor driver and a magnetic encoder bracket which are connected in sequence. The potting colloid wraps the magnetic encoder, the copper column, the motor driver and the magnetic encoder bracket and is arranged in a cavity at the rear of the stator assembly.

9. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 8, characterized in that: The motor driver supplies power and communicates to the stator assembly via a cable, and the magnetic encoder detects the rotation speed and position accuracy of the rotor assembly.

10. The submersible brushless DC motor suitable for full sea depth closed-loop operation according to claim 1, characterized in that: The rotor assembly has 28 rotor magnets, and the stator core of the stator assembly has a 14-slot structure.

Images