Wireless energy transmission based superconducting magnetic levitation micro-thrust test bench

Abstract

The application discloses a superconducting magnetic suspension micro-thrust measuring device based on wireless energy transmission, which comprises a superconducting magnetic suspension thrust measuring rack, a wireless energy transmission device and related sensors and displacement control mechanisms. The device realizes long-time non-contact power supply for small electric thrusters carried on micro-nano satellites and is applied to long-period thrust measurement, whole-satellite attitude control and other ground experiments. The wireless energy transmission device is required to keep the output voltage stable for a long time. In order to ensure the reliability of experiments in the vacuum cabin, the device is required to have the function of real-time monitoring of the position of the wireless energy transmission coil and adjustment under the control of the outside of the cabin. In order to not introduce the interference of the bias torque of the wireless energy transmission coil during operation, the wireless energy transmission device is required to be coaxially installed with the superconducting composite bearing and the micro-nano satellite shell.

Description

Technical Field

[0001] This invention relates to the measurement of micro-thrust of space electric thrusters and the attitude control of the entire satellite, specifically a superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission. Background Technology

[0002] With the rapid development of micro and nanosatellites and the demand for high-precision drag-free control in various space missions, lightweight, small-sized, and high-specific-impulse space micro-thrusters have been rapidly developed. Common micro-thrusters include cold gas thrusters, pulsed plasma thrusters, ion thrusters, and Hall thrusters, which can generate steady-state thrust on the order of µN to mN. To improve the on-orbit reliability of micro-thrusters, it is necessary to accurately assess the thrust magnitude on the ground and conduct whole-satellite attitude control experiments. As a thrust measurement rig for measuring weak forces, it must meet the characteristics of high sensitivity, fast response, and high resolution. The superconducting magnetic levitation thrust measurement rig has a simple structure, high load-bearing capacity, high precision, and a lower friction loss coefficient. It can achieve levitation without the need for specific working fluid assistance, and it adopts a vacuum cryogenic environment, which can effectively simulate the working environment of outer space. Its suppression of zero drift is significantly better than other mechanical rigs, meeting the requirements of long-period thrust measurement.

[0003] Maintaining high-precision thrust measurement over extended periods is a significant challenge for magnetic levitation thrust test benches. Superconducting magnetic levitation thrust measurement employs a fully suspended measurement method isolated from the external environment, possessing a completely contactless, suspended characteristic. Therefore, the onboard electrical equipment cannot be directly connected to an external power source via wiring. Conventional power supplies, limited by size and mass, struggle to maintain energy output for several hours or even a day. Furthermore, the long-cycle ignition operation of the electric thruster requires a stable operating voltage, with voltage fluctuations below 0.01V to prevent them from affecting stable operation. Traditional batteries experience a slow voltage decrease as their charge depletes, making it difficult to meet the long-term, high-power power supply demands of the electric thruster. Therefore, achieving a stable, high-power voltage supply to the electric thruster in a contactless manner is the problem this invention aims to solve.

[0004] Devices that wirelessly transmit power to everyday household appliances can effectively solve the problem of contactless power supply. However, there are some challenges in mounting a wireless power transmission system on a superconducting magnetic levitation thruster. First, during stable operation, the horizontal or vertical offset between the power supply coil and the receiving coil must be limited to less than 10mm. Second, the subµN electromagnetic force generated between the coils during operation can cause interference torque on the moving frame, affecting the accuracy of micro-thrust measurement. Third, during long-cycle ignition tests, the thruster consumes a lot of power, resulting in a large offset of the satellite's center of mass, which changes the horizontality of the rotation plane and causes angular deviation between the receiving coil and the power supply coil.

[0005] Based on the above problems, this invention designs a superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission. Summary of the Invention

[0006] This invention addresses the need for long-cycle thrust measurement and evaluation of micro-thrusters, overcoming the aforementioned challenges by designing a superconducting magnetic levitation micro-thrust measurement platform based on wireless power transfer. The wireless power transfer system maintains a stable output voltage for extended periods with an error of less than 0.01V, effectively ensuring stable operation of the micro-thruster. The power supply coil's output voltage is adjustable between 0-48V to meet the thruster's operational requirements under different voltage conditions. The power supply coil is centrally mounted on the axis of the superconducting composite bearing, ensuring that the thrust frame is not affected by the bias torque caused by the minute electromagnetic forces between the coils during measurement, and also preventing excessive positional deviations between the two coils due to satellite oscillation, which could malfunction the wireless power transfer system. Two small laser displacement sensors are symmetrically mounted at both ends of the power supply coil in the wireless power transfer system for real-time monitoring of the working distance between the coils, preventing the coil spacing from exceeding the allowable operating range. The power supply coil is mounted on a connecting rod that can move in the Z-axis direction, meeting the requirement of controlling the coil spacing in the wireless power transfer system outside the vacuum chamber. The receiving coil is mounted above the micro-nano satellite, with no mechanical contact between the receiving coil and the power supply coil.

[0007] The magnetic levitation moving frame is equipped with a dual-axis tilt sensor and a linear motor that adjusts the center of gravity of the moving frame. The sensor is used to monitor the overall levelness of the satellite in real time and indirectly monitor the parallelism between the coils in the wireless power transmission system. The satellite's center of gravity shifts due to the consumption of working propellant during the long-term operation of the thruster. If the tilt exceeds the allowable range and causes abnormal wireless power supply, the linear motor can be wirelessly controlled from outside the cabin to adjust the position of the satellite's center of gravity and correct the levelness between the coils.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The structure of this invention includes: a wireless power transfer system and a superconducting magnetic levitation micro-thrust measurement system. The wireless power transfer system is the core component of the system, providing a stable power supply for long-term long-term thrust measurement and evaluation of the micro-thruster. It includes: a power supply coil, a receiving coil, an epoxy resin board, positioning holes, a square support, a small laser displacement sensor, and a wireless power transfer coil displacement control mechanism. The wireless power transfer coil displacement control mechanism includes: a stepper motor, a connecting rod, a movable optical panel, and a slide rail.

[0010] The superconducting magnetic levitation micro-thrust measurement system includes: a thrust frame, micro / nano satellites, a thruster, a thruster power module, a superconducting bearing, a measuring block, a dual-axis tilt sensor, a wireless leveling mechanism, a superconducting block array, a superconducting block sample holder, a vacuum chamber, a refrigerator cold head, and an optical panel.

[0011] In the wireless power transfer system, both the power supply coil and the receiving coil are fixed to a square epoxy resin plate, 2mm thick, for secure connection between the coils and other mechanisms. A square support bracket aligns and fixes the receiving coil to the superconducting bearing. Each coil has a 20mm diameter hole at its center to ensure the coil installation does not interfere with the normal operation of the superconducting magnetic levitation composite bearing. The superconducting bearing is secured to the upper and lower shells of the micro-nano satellite with bolts. Two small laser displacement sensors are symmetrically mounted at both ends of the power supply coil, with a range of 50mm and an accuracy of 0.1mm. These sensors are used to monitor the working distance between the coils in the wireless power transfer system in real time. The sensor readings can be read and recorded in real time outside the vacuum chamber via a data acquisition device. The coil displacement control mechanism in the wireless power transfer system is fixed to an optical panel. An optical panel with M5 array threaded holes is fixed to the internal stepper motor slider. The allowable travel of the slider on the slide rail is 200mm, with a displacement control accuracy of 0.1mm, meeting the requirements for changing the coil spacing.

[0012] The thruster and its power module are integrated and installed inside the microsatellite under test. A magnetically levitated moving frame is fixedly installed at the center of the microsatellite's side shell, used to carry the sensors required for thrust testing. A dual-axis tilt sensor is fixedly installed on one side of the magnetically levitated moving frame, with an angle measurement accuracy of 0.01° on the X and Y axes. It is used to measure the microsatellite's horizontal deviation in real time, and the measurement data also reflects the horizontal deviation between coils in the wireless power transfer system. A wireless leveling mechanism is fixedly installed on the other side of the magnetically levitated moving frame, installed along the frame's axis. Its working stroke is 150mm, and its displacement accuracy is 0.1mm. It can be wirelessly controlled from outside the vacuum chamber by a remote controller, and can carry a 200g mass block for reciprocating motion, compensating for the center of mass shift caused by the thruster consuming 100g of working propellant.

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

[0014] (1) A superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission can power the equipment on the thrust frame without cable connection, avoiding interference torque caused by cable contact friction; the output voltage of the wireless power transmission system can remain stable for a long time with an error of less than 0.01V, and the maximum output power can reach 100W, effectively ensuring the stable operation of the micro-thruster, and can be used for long-cycle µN level thrust measurement and evaluation.

[0015] (2) A superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission, wherein the power supply coil in the wireless power transmission system is installed in the center with the composite bearing of the magnetic levitation thrust frame to ensure that the thrust frame is not affected by the bias torque caused by the small electromagnetic force between the coils during measurement, and the relative position between the coils in the wireless power transmission system is not changed when the moving frame deflects.

[0016] (3) A superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission. The output voltage of the power supply coil can be adjusted arbitrarily between 0-48V, which can meet the working requirements of the thruster power supply module under different voltages, and can also meet the thrust measurement under different working voltage conditions of the same micro-thruster. The ignition and shutdown control of the micro-thruster can be realized by turning the wireless power transmission system on and off outside the vacuum chamber.

[0017] (4) A superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission. In the wireless power transmission system, small laser displacement sensors are mounted at both ends of the power supply coil for real-time monitoring of the coil spacing. This enables real-time monitoring of the working spacing of the coil outside the vacuum chamber, preventing the coil spacing from exceeding the normal operating range and affecting the power supply of the thruster.

[0018] (5) A superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission. The power supply coil in the wireless power transmission system is installed on the wireless power transmission coil displacement control mechanism. The working distance of the coil can be adjusted in real time outside the vacuum chamber according to the signal of the small laser displacement sensor, so as to ensure the stability of power supply and improve the repeatability of the experiment.

[0019] (6) A superconducting magnetic levitation micro-thrust measurement rig based on wireless power transmission, wherein the thrust measurement rig is equipped with a dual-axis tilt sensor for real-time measurement of the rig's levelness and a wireless leveling mechanism for correcting the levelness of the satellite's rotating plane. The leveling mechanism can be controlled according to the tilt signal to compensate for the center of mass shift of the moving frame caused by the consumption of the thruster's working fluid, ensuring that the angular deviation between coils in the wireless power transmission system is within the allowable working range and ensuring the stability of the power supply.

[0020] The beneficial effects of this invention are: it combines wireless power transfer technology with a superconducting magnetic levitation micro-thrust measurement system, possessing the advantages of wireless power transfer systems such as non-contact operation and high-power, long-term stable power supply, and superconducting magnetic levitation measurement systems such as low zero drift, high precision, and low friction loss coefficient. It also features sensors and corresponding adjustment mechanisms that can measure the coil spacing and parallelism in the wireless power transfer system in real time outside a vacuum chamber, ensuring the stability and repeatability of the coil power supply in the wireless power transfer system. This invention can meet the needs of long-cycle steady-state micro-thrust measurement for various types of micro-thrusters. Attached Figure Description

[0021] Figure 1 shows a superconducting magnetic levitation micro-thrust measurement platform based on wireless power transfer according to the present invention.

[0022] 1-Vacuum chamber, 2-Wireless power transfer coil displacement control mechanism, 3-Power supply coil, 4-Miniature laser displacement sensor, 5-Permanent magnet, 6-Receiving coil, 7-Support component, 8-Moving frame, 9-Dual-axis tilt sensor, 10-Thruster, 11-Wireless leveling mechanism, 12-Thruster power module, 13-Micro / nano satellite, 14-Measuring block, 15-Superconducting composite bearing, 16-Superconducting block array, 17-Sample rack, 18-Refrigerator cold head, 19-Optical panel, 20-Wireless control terminal

[0023] Figure 2 is a schematic diagram of the wireless power transfer coil displacement control mechanism of the present invention.

[0024] 201-Stepper motor, 202-Connecting rod, 203-Modible optical panel, 204-Slide rail

[0025] Figure 3 is a schematic diagram of the wireless power transfer coil of the present invention.

[0026] 301 - Epoxy resin board, 302 - Wireless power transmission coil, 303 - Positioning hole Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and implementation guidelines.

[0028] This invention relates to a superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission. Utilizing the pinning characteristics of superconductors in a vacuum environment and the strong unloading capacity of permanent magnet bias bearings, stable contactless levitation is achieved. The contactless power supply wireless power transmission system provides stable, long-term power to the electrical equipment on the thrust frame without affecting the normal operation of the superconducting magnetic levitation moving frame. Therefore, this invention designs a new method for long-term steady-state thrust measurement of micro-thrusters.

[0029] The superconducting composite bearing 15 is securely installed at the center of the upper and lower shells of the microsatellite 13, and the moving frame 8 is fixed at the center of the shells on both sides of the satellite, completing the basic framework construction. The alignment and installation of the wireless power receiving coil 6 with the superconducting composite bearing 15 is a crucial step. The receiving coil 6 is fixed to the microsatellite 13 via positioning holes 303 and a square support 7 made of epoxy resin. Epoxy resin is a non-magnetic material and does not affect the magnetic field distribution of the composite bearing. Above the receiving coil 6 is the power supply coil 3, with no mechanical contact between them. Two small laser displacement sensors 4 are symmetrically installed at both ends of the power supply coil 3, with a range of 50mm and an accuracy of 0.1mm. These sensors are used to monitor the working distance between the coils in the wireless power transfer system in real time. Referring to the sensor output signal, the coil distance is adjusted in real time via the wireless control terminal 20. The receiving coil 6 is connected to the thruster power module 12 inside the microsatellite 13 via wires to provide power.

[0030] The dual-axis tilt sensor 9, mounted on the magnetic levitation moving frame, has a measurement accuracy of 0.01° in the X and Y axes. It is fixedly mounted on the moving frame 8 and secured to the mounting surface with bolts. The wireless leveling mechanism for adjusting the center of gravity of the moving frame has a working stroke of 150mm and a displacement accuracy of 0.1mm. It can be wirelessly controlled from outside the vacuum chamber by a remote control and is installed along the long axis of the thrust frame arm and secured with bolts.

[0031] As shown in Figure 2, the wireless power transmission coil displacement control mechanism consists of 201-stepper motor, 202-connecting rod, 203-movable optical panel, and 204-slide rail.

[0032] The power supply coil 3 is aligned and installed with the permanent magnet 5 on the fixed frame. It is then connected and fixedly mounted on the movable optical panel 203 via a connecting rod 202. The optical panel has M5 array threaded holes for fixing the connecting rod. After the coil is installed, the level is measured with a level and finely adjusted to be level. The slider has a permissible stroke of 200mm and can be moved up and down along the Z-axis from outside the vacuum chamber, with a displacement control accuracy of 0.1mm.

[0033] As shown in Figure 3, the wireless power transmission coil consists of 301-epoxy resin board, 302-wireless power transmission coil, and 303-positioning hole. Both the power supply coil and the receiving coil are fixed on a square resin board with a side length of 150mm and a thickness of 2mm. The power supply coil is aligned with the permanent magnet on the fixed frame and fixed on the fixed frame. The receiving coil is aligned with the thrust frame composite bearing through a square epoxy resin support. There is a 20mm diameter circular hole at the center of both coils to ensure that the installation of the coils does not affect the normal operation of the superconducting magnetic levitation composite bearing.

[0034] The operation is as follows:

[0035] Turn on the wireless power transmission device and put it into working mode. Adjust the voltage of the receiving coil 6 so that the output voltage meets the working voltage of the micro-thruster 10 under test. After the electrical test is completed, turn off the DC regulated power supply. Install all equipment on the optical panel 19 inside the vacuum chamber. Close the door of vacuum chamber 1 and perform vacuum evacuation on vacuum chamber 1 until the internal pressure is below 10. -4 Pa; The cold head 18 of the refrigerator pre-cools the superconducting block array 16 fixed on the superconducting block sample holder 17. After cooling for 1.5 hours, the temperature of the superconducting block drops below 50K, reaching the superconducting state. The micro-nano satellite 13 is stably suspended, reaching the state required for the thrust measurement experiment.

[0036] Referring to the signal from the small laser displacement sensor 4, the wireless power transfer coil displacement control mechanism 2 is controlled outside the vacuum chamber 1 to move up and down along the Z-axis, adjusting the distance between the power supply coil 3 and the receiving coil 6 in the wireless power transfer system to the optimal working distance. The wireless power transfer system is then activated, and the receiving coil 6 begins to supply power. The thruster 10 enters the ignition state, and it can be observed that the balance position of the microsatellite 13 swings under the action of micro-thrust. If the working propellant of the thruster 10 is consumed excessively during prolonged ignition, the center of mass of the microsatellite 13 shifts, causing the signal of the dual-axis tilt sensor 9 to become abnormal. The wireless control terminal 20 controls the mass block installed on the wireless leveling mechanism 11 to move in 1mm increments along the axis of the moving frame 8. The output signal of the tilt sensor is observed after each step until the X and Y axis angles are both zero, at which point the adjustment ends, the center of mass shift compensation is completed, and the levelness of the microsatellite 13 returns to normal, ensuring the levelness between the power supply coil 3 and the receiving coil 6. After the long-cycle steady-state thrust test is completed, power supply coil 3 is turned off, thruster 10 and thruster power module 12 are shut down, and wireless control terminal 20 controls wireless energy transmission coil displacement control mechanism 2 to rise by 100mm and lock it to prevent the stepper motor from descending on its own under load. The electrical switches inside the vacuum chamber and the signal communication with the sensors are then turned off. Subsequently, the refrigerator, vacuum pump, and other mechanical equipment are shut down, completing the test. Once the superconducting block array returns to room temperature, the vacuum chamber is vented. When the pressure returns to atmospheric pressure, the vacuum chamber can be opened and the equipment removed.

Claims

1. A superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission, characterized in that, include: Wireless power transfer system, superconducting magnetic levitation micro-thrust measurement system, wireless power transfer coil displacement control mechanism; The wireless power transmission system includes: a power supply coil, a receiving coil, a support component, a positioning hole, and a small laser displacement sensor; The superconducting magnetic levitation micro-thrust measurement system includes: a vacuum chamber, a micro / nano satellite, a thruster, a thruster power module, a moving frame, a wireless leveling mechanism, a dual-axis tilt sensor, a measuring block, a superconducting composite bearing, a superconducting block array, a superconducting block sample holder, a refrigerator cold head, and an optical panel. The wireless power transmission coil displacement control mechanism includes a stepper motor, a connecting rod, a movable optical panel, and a slide rail; In the wireless power transfer system, the power supply coil is aligned with the axis of the superconducting composite bearing, and the receiving coil is fixedly installed to the microsatellite via positioning holes and an epoxy resin support. The power supply coil is located above the receiving coil, with no mechanical contact between them. The power supply coil is fixed below the connecting rod of the wireless power transfer coil displacement control mechanism. Two small laser displacement sensors are symmetrically installed at both ends of the power supply coil. During operation, the receiving coil supplies power to the thruster power module inside the microsatellite. The wireless power transfer system is used to provide high-power, long-term power to the microsatellite in a contactless manner. The superconducting composite bearing is fastened at the center of the upper and lower shells of the micro-nano satellite, and the moving frame is fixed at the center of the shells on both sides of the satellite. The moving frame is equipped with a dual-axis tilt sensor and a wireless leveling motor. The dual-axis tilt sensor measures the levelness of the micro-nano satellite in real time. The measurement accuracy of the dual-axis tilt sensor is 0.01°. The wireless leveling motor has a stroke of 150mm. Below the superconducting composite bearing is a superconducting block array, which is placed in a superconducting block sample holder. The cold head of the refrigerator pre-cools the superconducting block array fixed on the superconducting block sample holder. The wireless power transmission coil displacement control mechanism is located on the side of the micro-nano satellite. A connecting rod is installed on the movable optical panel, and a power supply coil is installed below the connecting rod. A stepper motor controls the movable optical panel to move on the slide rail.

2. The superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission as described in claim 1, characterized in that, The relative distance between the power supply coil and the receiving coil in the wireless power transfer system does not change when the micro-nano satellite rotates, enabling the wireless power transfer system to provide long-term stable power to the micro-thruster and micro-nano satellite.

3. The superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission as described in claim 1, characterized in that, The wireless power transfer system can maintain a stable and adjustable voltage with an accuracy of 0.01V for an extended period of time, meeting the stable operation requirements of the micro-thruster under different operating voltages.

4. The superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission as described in claim 1, characterized in that, Wireless ignition and shutdown control allows for the control of the micro-thruster on the micro-satellite from outside the vacuum chamber by controlling the switch of the power supply coil in the wireless power transmission system, eliminating the need for redundant control switches on the thrust measurement rig.

5. The superconducting magnetic levitation micro-thrust measurement platform based on wireless power transmission as described in claim 1, characterized in that, The small laser displacement sensors installed at both ends of the power supply coil are used to measure the distance between the power supply coil and the receiving coil; the stepper motor controls the position of the power supply coil according to the measurement results of the small laser displacement sensors, and the distance between the power supply coil and the receiving coil can be adjusted within a range of 15mm in a vacuum environment.

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