A time delay occultation method and permanent magnet synchronous motor system

Abstract

This invention belongs to the field of motor control technology, specifically a delayed star-sealing method and a permanent magnet synchronous motor system. After receiving a power-off signal from the motor's main power supply, the circuit between the inverter and the motor's three-phase windings remains open. The current rotor speed is monitored in real time. When the current speed exceeds a preset star-sealing start threshold, the inverter is controlled to convert the three-phase AC power generated by the rotor's inertial rotation into DC power and store it in an energy storage module. When the current speed decreases to the star-sealing start threshold, the circuit between the inverter and the motor's three-phase windings is first disconnected, and then the star-sealing contactor is closed, short-circuiting the motor's three-phase windings to achieve star-sealing braking. This invention avoids the large current impact during high-speed star-sealing by delaying the star-sealing timing to a low-speed range, while simultaneously recovering and storing inertial energy at high speeds, thus balancing braking safety and energy utilization efficiency.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, specifically a delayed star-sealing method and a permanent magnet synchronous motor system. Background Technology

[0002] The statements in this section merely refer to the background art related to this invention and do not necessarily constitute prior art.

[0003] Permanent magnet synchronous motors (PMSMs) are widely used in applications requiring frequent starts and stops, such as electric vehicles, rail transit, and industrial automation, due to their high efficiency, high power density, and strong overload capacity. Common braking methods for these motors include regenerative braking, reverse braking, and mechanical braking. Reverse braking and mechanical braking generate significant current surges and mechanical wear during operation, adversely affecting the lifespan of components. In contrast, braking is achieved by short-circuiting the three-phase windings of the motor, utilizing the rotor's permanent magnet magnetic field to cut the stator windings and generate reverse electromagnetic torque. This method is simple in structure and requires no external energy source; it is called star-mounted braking.

[0004] For star-shaped braking, when the motor is rotating at high speed, directly short-circuiting the three-phase windings will instantly generate extremely high induced currents in the stator windings, producing a large amount of Joule heat. In severe cases, this can lead to winding insulation damage or even burnout, along with the risk of high-temperature demagnetization of the permanent magnets. To avoid this hazard, existing solutions often rely on complex contactor interlocking and timing protection circuits, but these still cannot fundamentally eliminate the large current surge during high-speed star-shaped braking. Summary of the Invention

[0005] This invention provides a delayed star-sealing method and a permanent magnet synchronous motor system, which overcomes the safety hazards of existing star-sealing braking technology, such as the huge inrush current generated by directly short-circuiting the three-phase windings during high-speed power failure, which can easily cause overheating damage to the windings and demagnetization of the permanent magnets. It achieves safe recovery and energy storage of inertial energy in the high-speed range and smooth and reliable entry of star-sealing braking in the low-speed range, ensuring safe and efficient braking of the motor across the entire speed range.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of this invention discloses a delayed satellite sealing method, comprising the following steps: Obtain the main power supply failure signal of the motor and maintain the circuit continuity between the inverter and the three-phase windings of the motor; Detect the current speed of the motor rotor; When the current speed is higher than the preset star-sealing start threshold, the inverter is controlled to convert the three-phase AC power generated by the rotor's inertial rotation into DC power and store it in the energy storage module. When the current speed drops to the star-sealing start threshold, the circuit between the inverter and the motor three-phase windings is first disconnected, and then the star-sealing contactor is closed to short-circuit the motor three-phase windings, thereby achieving star-sealing braking.

[0007] Furthermore, the sealing start threshold is determined using a dynamic adaptive method, specifically by real-time correction of the reference sealing speed threshold based on at least one parameter, namely, the capacitor state of charge and the load inertia.

[0008] Furthermore, the method for correcting the satellite sealing start threshold based on the capacitor's state of charge is as follows: When the capacitor is in a high state of charge, the satellite sealing start threshold is increased to terminate energy storage in advance and switch to satellite sealing braking. When the capacitor is in a low state of charge, the satellite sealing start threshold is lowered and the satellite sealing braking is delayed to extend the energy storage time.

[0009] Furthermore, the method for adjusting the star-sealing start threshold based on load inertia is as follows: When the load inertia is greater than the preset value, the star sealing start threshold is raised to seal the star earlier and shorten the coasting time. When the load inertia is less than the preset value, the star-sealing start threshold is lowered to delay the star-sealing and fully recover the low-speed inertial energy.

[0010] Furthermore, the determination of the satellite sealing start threshold adopts a combination of offline calibration and real-time correction: the reference satellite sealing speed table under different working conditions is pre-calibrated and stored in the MCU program memory. The MCU uses linear interpolation and weighted correction algorithms to fine-tune the reference value obtained from the table lookup based on parameters such as real-time collected speed, capacitor state of charge, and speed drop slope.

[0011] Furthermore, during the process of controlling the disconnection of the circuit between the inverter and the three-phase winding of the motor and then controlling the closing of the star-sealing contactor, the contactor action delay is compensated by the speed advance prediction method: the speed drop slope is calculated in real time through the speed decay algorithm, the remaining time for the speed to drop to the star-sealing start threshold is estimated, the total action delay is deducted by the contactor disconnection delay, safety dead time and engagement delay, and the advance command time is calculated and the control command is pre-issued.

[0012] Furthermore, while issuing control commands in advance, hardware feedback from the auxiliary contacts of the contactor is introduced for interlocking verification. Only when the contacts of the preceding contactor are detected to be completely open is the control circuit of the subsequent star-sealed contactor allowed to be turned on, ensuring the action sequence of opening before closing.

[0013] Furthermore, the energy storage module is a supercapacitor bank, and its energy storage array adopts a hybrid topology structure of first series and then parallel connection: multiple individual capacitors are connected in series to increase the operating voltage, and several series capacitor banks are connected in parallel to expand the total energy storage capacity.

[0014] A second aspect of the present invention discloses a permanent magnet synchronous motor system, comprising: Permanent magnet synchronous motor module, used to realize bidirectional conversion of electrical energy and mechanical energy; The resolver speed detection module is used to detect the speed of the motor rotor and output a speed signal; The MCU main control module is connected to the resolver speed detection module to receive the speed signal and output a first control signal or a second control signal based on the comparison result of the speed signal and the preset star-sealing start threshold. The three-phase bidirectional inverter module has its AC side connected to the three-phase windings of the motor via a first contactor, and its DC side connected to the energy storage module. In response to the first control signal, the three-phase bidirectional inverter module rectifies the three-phase AC power generated by the inertial rotation of the motor into DC power and delivers it to the energy storage module. The high-speed energy storage module is connected to the DC side of the three-phase bidirectional inverter module and is used to store DC power. The low-speed star-sealing circuit includes a star-sealing contactor. The three main contacts of the star-sealing contactor are respectively connected to the U, V, and W phase winding leads of the motor. The star-sealing contactor closes in response to the second control signal, short-circuiting the three phase windings of the motor. The MCU main control module outputs a first control signal when the current speed is higher than the sealing start threshold, and outputs a second control signal to close the sealing contactor when the current speed drops to the sealing start threshold.

[0015] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects: After the main power supply to the motor is cut off, the star-sealing braking is not immediately executed. Instead, the inverter circuit is kept conducting first, and the three-phase AC power generated by the rotor's inertial rotation is rectified and stored in the energy storage module. When the speed naturally decreases to a safe threshold, the inverter circuit is disconnected and the star-sealing contactor is closed to achieve safe star-sealing braking at low speeds. By delaying the star-sealing timing to the low-speed range, the high current surge caused by excessively high induced electromotive force during high-speed star-sealing is fundamentally avoided, preventing the risk of winding overheating and permanent magnet demagnetization. At the same time, the inertial energy at high speeds is recovered and stored, achieving efficient energy utilization. Furthermore, automatic switching between energy storage and star-sealing is achieved through speed threshold control, balancing braking safety and energy recovery efficiency. Attached Figure Description

[0016] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0017] Figure 1Axonometric drawing of a permanent magnet synchronous motor system provided for one or more embodiments of the present invention; Figure 2 Rear axonometric view of a permanent magnet synchronous motor system provided for one or more embodiments of the present invention; Figure 3 An exploded view of a permanent magnet synchronous motor module drive device provided in one or more embodiments of the present invention; Figure 4 Exploded view of a motor rotor provided for one or more embodiments of the present invention; Figure 5 A front exploded view of the housing and support device provided in one or more embodiments of the present invention; Figure 6 An exploded rear view of the housing and support device provided for one or more embodiments of the present invention; Figure 7 Exploded view of a heat dissipation device provided in one or more embodiments of the present invention; Figure 8 An exploded view of a resolver speed detection module provided in one or more embodiments of the present invention; Figure 9 Axonometric view of a three-phase bidirectional inverter device provided in one or more embodiments of the present invention; Figure 10 An energy storage DC-DC converter provided in one or more embodiments of the present invention; Figure 11 Isometric views of a high-speed energy storage module and an auxiliary power module provided for one or more embodiments of the present invention; Figure 12 This is a schematic diagram of the wiring terminals of a high-speed energy storage module and an auxiliary power supply module provided for one or more embodiments of the present invention.

[0018] Figures 1-2 The components are: 1. Permanent magnet synchronous motor module; 2. Three-phase bidirectional inverter device; 3. Energy storage DC-DC converter; 4. High-speed energy storage module; 5. Resolver speed detection module; 6. Star-sealed circuit contactor. Figures 3-7 In the middle: 11 Motor stator, 12 Motor rotor, 13 Motor shaft, 14 Rotor weight reduction slot, 15 One-line permanent magnet slot, 16 V-type permanent magnet slot, 17 Permanent magnet, 18 Front cover, 19 Main body shell, 110 Support bearing, 111 Bearing mounting groove, 112 Junction box, 113 Motor support base, 114 Cooling fan, 115 Cooling end cover; Figure 8 In the middle: 51 resolver rotor, 52 resolver stator, 53 resolver fixed support, 54 resolver end cover; Figure 9 In the middle: 21 AC side connection terminal of inverter, 22 DC side connection terminal of inverter; Figure 10 In the middle: 31 DC-DC converter high-voltage side wiring terminal; 32 DC-DC converter low-voltage side wiring terminal; Figures 11-12 In the middle: 41 Capacitor bank energy storage module, 42 First output auxiliary power supply module DC-DC converter, 43 Second output auxiliary power supply module DC-DC converter, 44 Energy storage converter side terminal, 45 First auxiliary power supply side terminal of capacitor bank, 46 Second auxiliary power supply side terminal of capacitor bank, 47 First auxiliary power supply capacitor bank side terminal, 48 First auxiliary power supply output side terminal, 49 Second auxiliary power supply capacitor bank side terminal, 410 Second auxiliary power supply output side terminal. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0021] As described in the background section, existing star-sealing braking technology suffers from a large inrush current during high-speed power failure due to the direct short circuit of the three-phase windings, which can easily cause overheating and damage to the windings and demagnetization of the permanent magnets. The root cause lies in the lack of a differentiated strategy based on speed dimension in the timing control of star-sealing braking. In other words, existing solutions treat star-sealing braking as a binary decision of "no star-sealing / immediate star-sealing after power failure," ignoring the decisive influence of motor speed on the star-sealing current. Since the induced electromotive force is proportional to the speed, high-speed star-sealing inevitably involves a high-current inrush, a direct consequence of the law of electromagnetic induction.

[0022] This solution provides a delayed star-sealing method and a permanent magnet synchronous motor system. After the motor is powered off, the inverter circuit is kept on to rectify the AC power generated by the rotor's inertial rotation and store it in the capacitor bank. When the speed drops to a safe threshold, the inverter circuit is disconnected and the star-sealing contactor is closed to achieve safe star-sealing braking at low speeds, taking into account both energy recovery and braking safety.

[0023] Figure 1 The front axle view of the permanent magnet synchronous motor system includes a permanent magnet synchronous motor module 1, a three-phase bidirectional inverter device 2, an energy storage DC-DC converter 3, a high-speed energy storage module 4, and a resolver speed detection module 5.

[0024] In this embodiment, the permanent magnet synchronous motor module 1 is independently installed on one side of the base, while the other side of the base is used to house the three-phase bidirectional inverter device 2, the energy storage DC-DC converter 3, the high-speed energy storage module 4, and the resolver speed detection module 5. This facilitates the export, import, and connection of the wiring for each module.

[0025] The permanent magnet synchronous motor module 1 converts three-phase AC power into mechanical energy for shaft rotation, and converts the mechanical energy of the shaft during inertial rotation into three-phase AC power.

[0026] The three-phase bidirectional inverter device 2 realizes the mutual conversion between three-phase AC and DC power. When the motor is in the starting state, the energy storage module outputs voltage, and the three-phase bidirectional inverter device 2 receives DC power from the DC-DC converter 3 and converts it into the three-phase AC power required by the motor. When the motor is de-energized, the shaft continues to rotate under inertia, driving the motor rotor to rotate. The permanent magnet inside the rotor continuously cuts the stator windings, generating three-phase AC power in the windings. At this time, the three-phase bidirectional inverter device 2 receives the three-phase AC power from the motor and converts it into DC power for energy storage.

[0027] The energy storage DC-DC converter 3 is used for voltage boosting and bucking. When current flows from the motor to the energy storage module, the energy storage DC-DC converter 3 performs a step-down function, reducing and limiting the drastically changing high-voltage DC current emitted by the motor at different speeds to precisely match the charging voltage and current required by the energy storage module. When current flows from the energy storage module to the motor, it actively boosts the lower and fluctuating voltage output by the energy storage module to a stable and ideal DC bus high voltage for motor starting.

[0028] The high-speed energy storage module 4 is used to store and release electrical energy. When the motor is de-energized and the rotor continues to rotate under inertia, the three-phase AC power generated by the motor is rectified into DC power by the three-phase bidirectional inverter device 2, and then stepped down by the DC-DC converter 3 before being sent to the high-speed energy storage module 4 for storage, thus recovering inertial energy. When the motor is in the starting state, the electrical energy stored in the high-speed energy storage module 4 is stepped up by the DC-DC converter 3 and then converted into the three-phase AC power required by the three-phase bidirectional inverter device 2, thus enabling the motor to start automatically.

[0029] The resolver speed detection module 5 is used to detect the rotor speed of the motor in real time. When the motor is powered off and the shaft continues to rotate under inertia, the resolver speed detection module 5 is installed at the tail of the motor and rotates synchronously with the shaft. It senses the change in rotor angle through the resolver, and after being processed by the resolver decoding chip, it outputs a real-time speed signal to the MCU main control module, providing a speed basis for determining whether the motor should be in a high-speed energy storage state or a low-speed star-sealing state.

[0030] After the permanent magnet synchronous motor module 1 is powered off, the shaft continues to rotate under inertia, and the motor generates AC power, which is converted into DC power by the three-phase bidirectional inverter device 2. After being stepped down by the energy storage DC-DC converter 3, it is sent to the high-speed energy storage module 4 for storage, which is used for the working power of the MCU main control module and other modules, as well as the auxiliary power for the next start of the motor.

[0031] The MCU main control module is used to receive power supply and shutdown information, speed information, set the starting speed of the star circuit, and control the opening and closing of the contactor.

[0032] When the motor is operating normally, the contactor connecting the inverter and the three-phase windings of the motor is in the closed state, and the star-sealing circuit contactor is in the open state. The main power supply continues to provide power, and the star-sealing circuit does not start.

[0033] Once a power outage is detected in the motor, the rotational speed of the shaft under inertia is received in real time. The device is in a high-speed energy storage state until the starting speed of the star-sealing circuit is reached. When the speed drops to the starting speed of the star-sealing circuit, the contactor connecting the inverter and the three-phase windings of the motor is immediately disconnected, and the star-sealing circuit contactor is closed, thus starting the star-sealing circuit.

[0034] The MCU main control module obtains the inherent action delay reference values ​​of the two types of contactors through actual measurement. The disconnection delay, engagement delay, and safety dead time are calibrated offline and then stored in the MCU program memory as basic delay parameters. The module calibrates and stores the disconnection delay of the preceding contactor, the engagement delay of the following star-sealed contactor, and the circuit safety dead time. A software-based timing delay compensation mechanism is used in the control timing. After issuing the command to disconnect the main circuit contactor, the module waits for the calibrated disconnection delay to be superimposed with the safety dead time before issuing the star-sealed contactor closing command. Simultaneously, hardware feedback from the contactor auxiliary contacts is introduced for interlocking verification. Only after the preceding contactor contacts are detected to be completely disconnected is the subsequent star-sealed contactor control circuit allowed to conduct. Through software timing compensation and hardware contact closed-loop verification, the inherent delay of the contactors is accurately offset, strictly ensuring the action sequence of disconnection followed by closing, and preventing short-circuit faults caused by simultaneous conduction of the upper and lower circuits.

[0035] In subsequent operation, the contactor delay is dynamically updated simultaneously. By calculating the speed drop slope in real time, the remaining time to reach the star-sealing threshold is estimated, the total action delay is dynamically deducted, and the advance command time is calculated to offset the inherent delay deviation of the contactor. Load inertia adaptive correction, combined with load inertia identification, adaptively adjusts the delay prediction advance to match the speed decay characteristics under different loads, further optimizing the delay accuracy.

[0036] The system employs a speed prediction method to compensate for the overall contactor action delay. It relies on a resolver module to collect motor speed data in real-time at high frequency. Based on the real-time sampled data, it calculates the current actual speed drop slope and uses this to estimate the remaining time before the speed drops to the star-sealing threshold. After deducting the total action delay of contactor disconnection, safety dead zone, and engagement, it reverses and pre-issues control commands. During the process, the speed sampling signal is low-pass filtered for noise reduction, and the prediction lead is adaptively corrected using load inertia identification. Ultimately, the system achieves precise matching between the moment the star-sealing contactor contacts fully close and the moment the motor speed reaches the set threshold.

[0037] Figure 2 This is a rear axle view of a permanent magnet synchronous motor system, including the star-sealed circuit contactor 6 and the resolver detection module 5.

[0038] The resolver detection module 5 is installed at the rear of the motor and is used to detect the rotational speed of the shaft under inertial rotation in real time after the motor is powered off. The speed signal is then sent to the MCU main control module, which determines whether to maintain the energy storage working state or the satellite shutdown working state based on the preset speed threshold.

[0039] The sealing circuit contactor 6 can short-circuit the three-phase windings. After the three-phase windings are short-circuited, the motor rotor continues to rotate under the action of inertia. The magnetic field of the permanent magnet inside the rotor cuts the stator windings to generate back electromotive force, which stops the rotor from rotating and achieves rotor braking.

[0040] Figure 3 This is an exploded view of the permanent magnet synchronous motor module drive unit. It includes the motor stator 11, the motor rotor 12, and the motor shaft 13.

[0041] The motor stator 11 is a cylindrical structure made of stacked stator silicon steel sheets with 24 slots and an insulating coating on the surface. Four positioning ribs protrude symmetrically around the outside of the motor stator. The 24 slots are used for winding the three-phase AC windings, which consist of coils wound with insulated copper wire and connected in a specific manner to form symmetrical U, V, and W three-phase windings.

[0042] The motor rotor 12 is made of stacked silicon steel sheets. The silicon steel sheets have V-shaped and I-shaped slots for placing permanent magnets, as well as slots for weight reduction and heat dissipation. All slots are evenly arranged circumferentially. The silicon steel sheets have a through hole at their center and symmetrical inward-facing lugs for mating with the shaft.

[0043] The motor shaft 13 is designed as a stepped shaft, with a spline at the left end for power connection with the load and transmission of torque. The middle section has two long slots for circumferential fixation and torque transmission with the through hole at the center of the motor rotor. The right side is divided into three sections, each for mounting the bearing, cooling fan, and resolver.

[0044] Figure 4 This is an exploded view of the motor rotor. It includes rotor weight reduction slot 14, straight permanent magnet slot 15, V-shaped permanent magnet slot 16, and permanent magnet 17.

[0045] The rotor weight reduction slot 14 is used to reduce the amount of rotor material used, reduce the overall weight of the motor, and at the same time facilitate the heat dissipation of the rotor core and permanent magnets, reduce the rotor temperature, and prevent the permanent magnets from demagnetizing due to high temperature.

[0046] The straight permanent magnet slot 15 and the V-shaped permanent magnet slot 16 are used for the installation of permanent magnet 17. The V-shaped permanent magnets are arranged obliquely to form a magnetic focusing effect, which gathers the magnetic lines of force and increases the magnetic flux density in the air gap. The straight permanent magnets are arranged radially to supplement the main magnetic flux of the foundation. The composite structure has small torque pulsation, low operating vibration and noise, higher rotor mechanical strength and is suitable for high-speed operation. It can also optimize the amount of magnet used, and reduce manufacturing costs while taking into account high and low speed power performance.

[0047] Figure 5 This is a front exploded view of the casing and support assembly. It includes the front cover 18, the main body casing 19, and the support bearing 110.

[0048] The front cover 18 has a circumferentially arranged heat dissipation groove at the top front end, a groove for installing the support bearing 110 in the middle, and a circumferentially arranged lug with threaded through holes at the rear. The front end of the main body shell 19 also has a circumferentially arranged lug with threaded through holes, which is connected and fixed to the lug of the cover 18 by bolts.

[0049] Figure 6 This is a rear exploded view of the housing and support assembly. It includes the bearing mounting groove 111, the junction box 112, and the motor support base 113.

[0050] The bearing mounting grooves 111 are designed on the front end of the front cover 18 and the rear end of the main body shell 19, respectively, to support the installation of the bearings 110, thereby supporting the rotor shaft, limiting the radial and axial positions of the shaft, ensuring the concentricity of the rotor and stator, reducing the frictional resistance when the shaft rotates, reducing wear and energy consumption, protecting the motor shaft and internal structure, and extending the service life of the whole machine.

[0051] Junction box 112 is installed on the outside of the main body housing 19, and has three terminals. It is internally conductive and is used for the outgoing of three-phase AC winding wiring and external connection of three-phase power lines.

[0052] The motor support 113 is installed on the lower part of the outer casing 19 to support the entire motor.

[0053] Figure 7 This is an exploded view of the heat dissipation device. It includes a cooling fan 114 and a heat dissipation end cover 115.

[0054] The cooling fan 114 is fixed to the rear of the motor shaft 13. When the motor shaft 13 rotates, it drives the cooling fan 114 to rotate. The fan carries away some of the heat generated by the motor through the airflow, thus achieving a certain degree of heat dissipation.

[0055] The heat dissipation end cap 115 has heat dissipation slots on the outside to facilitate heat dissipation.

[0056] The heat dissipation end cover 115 has circumferentially arranged threaded through holes on its outer side for connection and fixation with the main body casing 19. A threaded through hole is opened in the center of the rear surface for fixing the resolver.

[0057] Figure 8 This is an exploded view of the resolver speed detection module. It includes the resolver rotor 51, resolver stator 52, resolver fixed support 53, and resolver end cover 54.

[0058] The resolver rotor 51 is a solid iron core with multiple salient poles formed by stacking multiple silicon steel sheets. At the same time, the inner circle of the iron core is provided with protruding positioning ribs for fixing with the motor shaft 13.

[0059] The resolver stator 52 is composed of multiple iron-nickel soft magnetic alloy discs stacked together, each with 10 slots on its inner circumference. It also features heat dissipation slots on its surface to reduce weight and improve heat dissipation. The resolver windings are divided into excitation windings, sine windings, and cosine windings. The excitation windings are wound on all stator teeth, while the sine and cosine windings are grouped with a 90° spatial phase difference. A high-frequency excitation alternating current is applied to the stator to generate an alternating magnetic field. The rotor rotates synchronously with the motor shaft. The coupling magnetic flux between the stator and rotor windings changes with the rotation angle, inducing a modulated voltage in the stator's sine and cosine output windings whose amplitude varies with the rotor rotation angle according to a sine and cosine law. The back-end controller demodulates and processes these two signals to accurately calculate the real-time rotor speed and transmits the speed signal to the MCU main control module.

[0060] The resolver mounting bracket 53 is designed as a multi-layered boss shape. The lower boss has threaded through holes around its circumference and is fixed to the rear surface of the heat dissipation end cover 115 with bolts. The upper boss of the resolver mounting bracket 53 has a groove in the center for mounting the resolver rotor 51 and resolver stator 52. At the same time, it is provided with wiring terminals on the outside to facilitate the output of winding wiring and external connection of high-frequency excitation AC power.

[0061] The resolver end cap 54 has circumferentially arranged lugs with threaded holes at its bottom for connection and fixation with the threaded holes of the lower boss. The resolver end cap 54 has six through holes on its outer side for wire routing. The top surface of the resolver end cap 54 has heat dissipation grooves for easy heat dissipation.

[0062] Figure 9 This is an isometric view of a three-phase bidirectional inverter unit. The labels in the diagram are 21 for the AC side and 22 for the DC side of the inverter.

[0063] The inverter's AC side terminal 21 is electrically connected to the terminal block of the junction box 112 for AC power input and output. When the motor is operating normally, the inverter's AC side terminal 21 outputs three-phase AC power to the three-phase windings of the motor stator 11. After the motor is de-energized, the magnetic field of the motor rotor's permanent magnet cuts the motor stator windings, generating a three-phase induced current in the three-phase windings, which is then input to the inverter's AC side terminal 21.

[0064] The inverter's DC side terminal 22 is used for both DC power input and output. When the motor is operating normally, the inverter's DC side terminal 22 receives DC power from the power supply or energy storage module. After the motor is powered off, the inverter's DC side terminal 22 outputs DC power converted from three-phase AC power to the energy storage module.

[0065] Figure 10 This is an energy storage DC-DC converter. The diagram shows the high-voltage side terminal 31 and the low-voltage side terminal 32 of the DC-DC converter.

[0066] The high-voltage side terminal 31 of the DC-DC converter is electrically connected to the DC side terminal 22 of the inverter, used to output high-voltage DC power to the inverter or receive high-voltage DC power from the inverter. The low-voltage side terminal 32 of the DC-DC converter is electrically connected to the terminal of the capacitor bank energy storage module, used to output low-voltage DC power to the capacitor bank energy storage module or receive low-voltage DC power from the capacitor bank energy storage module. This enables the capacitor bank energy storage module to perform boost discharge when driving the motor and step-down charging of the capacitor bank energy storage module by the motor's inertial power generation.

[0067] Figure 11 This is an isometric view of the high-speed energy storage module and auxiliary power supply module. It includes the capacitor bank energy storage module 41 and the auxiliary power supply module 42.

[0068] The energy storage module 41 uses a hybrid topology of series-parallel connection for its energy storage array. First, multiple individual capacitors are connected in series to increase the system operating voltage, and then several capacitor banks formed by the series connection are connected in parallel to expand the total energy storage capacity.

[0069] The auxiliary power supply module 42 is used to enable the capacitor bank energy storage module 41 to supply power to the MCU main control module and the star-sealing circuit.

[0070] Figure 12 This diagram shows the wiring terminals for the capacitor bank energy storage module and the auxiliary power supply module. It includes terminal 44 on the energy storage converter side, terminal 45 on the first auxiliary power supply side of the capacitor bank, terminal 46 on the second auxiliary power supply side of the capacitor bank, terminal 47 on the capacitor bank side of the first auxiliary power supply, terminal 48 on the output side of the first auxiliary power supply, terminal 49 on the capacitor bank side of the second auxiliary power supply, and terminal 410 on the output side of the second auxiliary power supply.

[0071] The energy storage converter side terminal 44 is electrically connected to the low-voltage side terminal 32 of the energy storage DC-DC converter, which is used for the energy storage DC-DC converter 3 to transmit low-voltage DC power to the capacitor bank energy storage module of the high-speed energy storage module 4 or to transmit low-voltage DC power from the capacitor bank energy storage module to the energy storage DC-DC converter 3.

[0072] The three-phase AC power generated after the motor is powered off is transmitted to the three-phase bidirectional inverter device 2 through the electrical connection between the junction box 112 and the AC side terminal 21 of the inverter. After being rectified into DC power by the three-phase bidirectional inverter device 2, it is transmitted to the energy storage DC-DC converter 3 through the electrical connection between the DC side terminal 22 of the inverter and the high-voltage side terminal 31 of the DC-DC converter. The energy storage DC-DC converter 3 steps down the voltage to low-voltage DC power, and then transmits it to the capacitor bank energy storage module 41 through the electrical connection between the low-voltage side terminal 32 of the DC-DC converter and the side terminal 44 of the energy storage converter, thus storing electrical energy. Conversely, the capacitor bank energy storage module 41 can supply power to the three-phase windings of the motor stator.

[0073] The capacitor bank first auxiliary power supply side terminal 45 and the first auxiliary power supply capacitor bank side terminal 47 are electrically connected for the transmission of DC power between the capacitor bank energy storage module of the high-speed energy storage module 4 and the first output auxiliary power supply module DC-DC converter 42.

[0074] Through the electrical connection between the first auxiliary power supply side terminal 45 and the first auxiliary power supply capacitor group side terminal 47, DC power flows from the capacitor group energy storage module of the high-speed energy storage module 4 to the first output auxiliary power supply module DC-DC converter 42. Through the electrical connection between the first auxiliary power supply output side terminal 48 and the MCU main control module, power is supplied to the MCU main control module.

[0075] The capacitor bank's second auxiliary power supply side terminal 46 is electrically connected to the second auxiliary power supply capacitor bank side terminal 49, which is used for the transmission of DC power between the capacitor bank energy storage module of the high-speed energy storage module 4 and the second output auxiliary power supply module DC-DC converter 43.

[0076] The capacitor bank's second auxiliary power supply side terminal 46 is electrically connected to the second auxiliary power supply capacitor bank side terminal 49, and the second auxiliary power supply output side terminal 410 is electrically connected to the star-sealing circuit contactor 6, so that the current flows from the capacitor bank energy storage module of the high-speed energy storage module 4 to the star-sealing circuit contactor 6.

[0077] The working process of the above permanent magnet synchronous motor system includes the following steps: Step 1: Precharge the capacitor bank energy storage module to a voltage sufficient to start the auxiliary power supply and the MCU main control module.

[0078] Step 2: When the motor starts, the voltage in the capacitor bank energy storage module is boosted by the energy storage DC-DC converter, and the DC current is converted into the three-phase AC power required for the motor stator drive by the inverter, thereby realizing the starting of the auxiliary motor. At this time, the contactor used to connect the inverter and the motor is in the closed state, and the star contactor is in the open state.

[0079] Step 3: The motor rotor rotates under the drive of the three-phase AC power in the motor stator, which in turn drives the shaft to rotate. At this time, the motor is in normal working condition.

[0080] Step 4: After the main power supply to the motor is cut off, the motor shaft continues to rotate under the action of inertia. The rotary transformer located at the tail of the motor transmits the speed information to the MCU main control module through the rotary decoder chip. The MCU main control module uses a built-in algorithm to determine the start and stop of the high-speed energy storage module and the low-speed star-sealing circuit of the motor according to the speed.

[0081] Step 5: The start-up threshold of the star-sealing circuit adopts dynamic adaptiveness to match various operating conditions of the motor. A combination of offline table lookup and real-time parameter algorithm correction is used.

[0082] The determination of the system's offline table calibration parameters adopts a single-variable control method, adjusting only one parameter each time while keeping the others fixed. The safest star-sealing speed under different conditions without large current impact, permanent magnet demagnetization, and braking balance is measured. The calibration data is averaged and outliers are removed. The average of three valid tests is used as the baseline threshold to create a basic star-sealing speed table for capacitor SOC, load inertia, and light and heavy load conditions. This table is then stored in the MCU program memory as the baseline threshold.

[0083] Using the maximum allowable short-circuit current of the winding as a safety constraint, the corresponding maximum allowable star-sealing speed is calculated in reverse. This speed is the theoretical safety boundary of the star-sealing threshold. First, the theoretical safe speed is calculated using the motor's physical parameters to determine the core boundary of the threshold. The calculation steps are as follows: Stator phase induced electromotive force The relationship with electric angular velocity is shown in equation (1): (1) In the formula, The rotor's electric angular velocity (rad / s) The fundamental flux linkage (Wb) of the rotor permanent magnet.

[0084] The relationship between electric angular velocity and motor speed is shown in equation (2): (2) In the formula, p This represents the number of pole pairs of the motor. n The value is the rotational speed.

[0085] Three-phase short-circuit star-sealed current The calculation formula is as shown in formula (3): (3) In the formula, Stator phase resistance (Ω) The stator phase inductance is (H).

[0086] Safety constraints lead to the maximum permissible star-sealing rotation speed Let the short-circuit current be equal to the maximum allowable value of the winding, and then we can obtain equation (4): (4) When the motor is in the high-speed range, the electrical angular velocity of the stator winding is The inductive reactance of the winding is much larger than that of the stator phase resistance. The contribution of the phase resistance to the short-circuit current limiting is negligible. Therefore, it can be simplified to equation (5): (5) The result calculated by equation (5) This is the theoretical benchmark value for the star-sealing threshold.

[0087] Through experimental verification using the single-variable control method, and after mean filtering and outlier removal, the average value of three valid tests was taken to finally form a basic satellite rotation speed meter that integrates theoretical calculations and engineering measurements, which was then stored in the MCU program memory.

[0088] The MCU collects real-time speed, capacitor SOC, and speed drop slope through the resolver module, voltage and current sampling, and energy storage module sampling. It then uses linear interpolation and weighted correction algorithms to fine-tune the lookup table reference value.

[0089] First, ensure that parameter adjustments are performed according to the priority from motor safety to performance efficiency. When the capacitor SOC is ≥ 95%, overcharge protection is activated, and the star-mounted protection is switched off in advance. When no high-priority protection is triggered, low-priority parameter adjustments are performed.

[0090] Based on the real-time acquired capacitor SOC and load inertia, the MCU first locates four adjacent reference threshold points V in the pre-stored basic satellite sealing speed threshold table. 11 V 12 V 21 V 22 First, linear interpolation is performed along the SOC dimension to obtain intermediate thresholds V1 and V2 under fixed inertia. Then, quadratic linear interpolation is performed along the load inertia J dimension to finally calculate the initial interpolation threshold corresponding to the current working condition.

[0091] During the correction, to ensure that device safety takes precedence over energy recovery and braking efficiency, the capacitor SOC weight value is greater than the load inertia weight value. The capacitor SOC weight W1 = 0.6 and the load inertia weight W2 = 0.4 are set so that the final satellite sealing start threshold is equal to the initial interpolation threshold + (W1 × SOC correction amount + W2 × inertia correction amount).

[0092] Both types of inertia corrections are pre-calibrated and stored in the MCU. The capacitor SOC correction is determined by measuring the capacitor SOC while keeping the load inertia constant. For low SOC (≤30%), more energy storage is needed, so the threshold correction is lowered to a negative value. For medium SOC (30% to 85%), no adjustment is needed, and the correction is 0. For high SOC (85% to 95%), overcharging prevention is needed, so the threshold is raised, and the correction is positive. The load inertia correction is determined by measuring the load inertia while keeping the capacitor SOC constant. For large inertia, the threshold is raised, and the correction is positive. For the baseline inertia, no adjustment is needed, and the correction is 0. For small inertia, more energy recovery is needed, so the threshold is lowered, and the correction is negative.

[0093] In cases where there is a conflict between lowering the threshold for SOC (≤30%) and raising the threshold for large inertia, the high-priority rule should be followed, and the threshold should be lowered based on the safety control of SOC. The logic for raising the threshold for large inertia should not be activated for the time being.

[0094] In cases where there is a conflict between increasing the threshold for SOC (85% to 95%) and decreasing the threshold for small inertia, the high-priority rule should be followed, and the upward correction instruction for SOC should be adopted, while the reverse correction on the inertia side should be blocked.

[0095] If the motor shaft speed is higher than the starting speed of the sealing circuit, it is in a high-speed energy storage state. At this time, the contactor used to connect the inverter and the motor is in a closed state under the control of the MCU. The magnetic field of the permanent magnet in the motor rotor cuts the stator winding and generates three-phase AC current in the stator winding, converting the mechanical energy of the rotor into electrical energy, which is fed to the inverter to be converted into DC current. After being stepped down by the DC-DC converter, it flows to the capacitor bank energy storage module to realize the storage of electrical energy.

[0096] Step 6: When the motor shaft speed decreases to the starting speed of the star-sealing circuit, the MCU main control module controls the contactor connecting the inverter and the motor to disconnect, and the star-sealing contactor closes to short-circuit the three-phase windings of the motor. At this time, the permanent magnet magnetic field of the motor rotor continues to cut the stator windings at low speed. The rotor rotation still generates an induced electromotive force, which produces a huge short-circuit current in the short-circuited stator windings, forming a strong passive electromagnetic braking torque, causing the rotor to stop rotating quickly.

[0097] For different motor operating conditions, the MCU monitors the capacitor's SOC change in real time. When the capacitor is about to be fully charged (SOC ≥ 85%), the star-sealing start speed is proactively increased in advance. At higher speeds, energy recovery is terminated, the inverter is disconnected, and the star-sealing contactor is closed to stop charging and prevent overcharging from damaging the components. For medium charge (30% < SOC < 85%), the calibrated reference threshold is maintained, with high-speed full energy storage and low-speed smooth star-sealing braking. For capacitor depletion (SOC ≤ 30%), the star-sealing start speed is delayed and reduced. The switching speed is lowered to utilize low-speed inertial power generation for energy replenishment as much as possible, maximizing energy recovery.

[0098] The MCU monitors the motor temperature in real time. In the cold state (winding temperature < 40℃), the winding resistance is low, the permanent magnet magnetic performance is optimal, the star-sealing braking force is sufficient, and the engagement threshold is appropriately lowered, allowing for lower speeds before engaging star-sealing to extend the energy storage time. In the hot state (winding temperature 80~120℃), the braking force significantly decreases, the engagement threshold is raised, and the higher induced electromotive force generated at slightly higher speeds is used to compensate for torque loss and ensure braking rigidity. In the over-temperature protection state (winding temperature ≥ 130℃), the star-sealing threshold is forcibly raised, energy storage is immediately discontinued, and star-sealing is engaged, prioritizing the protection of the motor body.

[0099] The MUC determines whether the moment of inertia is large or small based on the speed decay slope. With a large moment of inertia, the entry speed is increased, the star is closed earlier, the coasting time is shortened, and braking is rapid. With a small moment of inertia, the entry speed is decreased, the star is closed later, and the residual inertial energy at low speeds is fully recovered.

[0100] This scheme allows the rotor to rotate freely due to inertia after the motor is powered off, while the inverter circuit remains open to rectify and store the electrical energy generated by the rotor's rotation. Once the speed naturally decreases to a safe level, star-lock braking is then applied. During high-speed operation, star-lock braking is not applied; this inertial energy is converted from mechanical energy to electrical energy by the inverter and stored. Star-lock braking is then applied after a delay to allow the speed to decrease further, thus avoiding the problem of high current.

[0101] The braking requirements and energy recovery potential of a motor vary under different operating conditions. Using a fixed star-sealing threshold cannot simultaneously ensure energy recovery efficiency and braking reliability in different scenarios. Therefore, this solution introduces a dynamic adaptive mechanism: star-sealing is initiated early when the energy storage module is nearly fully charged to avoid overcharging damage; star-sealing is delayed when the energy storage module is depleted to recover as much energy as possible. When the motor is cold, the permanent magnets are strong and the braking torque is abundant, allowing for a slightly delayed star-sealing to extend the energy storage time; when the motor is hot, the braking force weakens, requiring early star-sealing to ensure braking reliability; and when the temperature exceeds the limit, immediate star-sealing is forced to prioritize the protection of the motor itself. For high-inertia loads with long coasting times, early star-sealing shortens the braking distance; for low-inertia loads, delayed star-sealing fully recovers residual energy at low speeds.

[0102] Meanwhile, a strict "break-then-close" procedure must be followed between "disconnecting the inverter circuit" and "closing the star-sealing contactor" to prevent short-circuit faults caused by simultaneous conduction of two circuits. However, the contactor itself has an inherent operating delay, which may cause a deviation between the actual star-sealing engagement time and the theoretical threshold time. To address this issue, this solution predicts the time to reach the threshold based on the speed drop slope, and issues the command in advance after deducting the contactor's operating delay, ensuring precise matching between the star-sealing contact closing time and the speed reaching the threshold. The hardware section uses the contactor's auxiliary contacts to provide real-time feedback on the status of the preceding contactor, allowing the subsequent contactor to close only after confirming complete disconnection, thus eliminating the possibility of simultaneous conduction at the hardware level.

[0103] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A delayed star-sealing method, applied to a permanent magnet synchronous motor system, characterized in that, Includes the following steps: Obtain the main power supply failure signal of the motor and maintain the circuit continuity between the inverter and the three-phase windings of the motor; Detect the current speed of the motor rotor; When the current speed is higher than the preset star-sealing start threshold, the inverter is controlled to convert the three-phase AC power generated by the rotor's inertial rotation into DC power and store it in the energy storage module. When the current speed drops to the star-sealing start threshold, the circuit between the inverter and the motor three-phase windings is first disconnected, and then the star-sealing contactor is closed to short-circuit the motor three-phase windings, thereby achieving star-sealing braking.

2. The delayed satellite sealing method as described in claim 1, characterized in that, The sealing start threshold is determined in a dynamic adaptive manner, specifically by real-time correction of the reference sealing speed threshold based on at least one of the following parameters: capacitor state of charge, motor winding temperature, and load inertia.

3. The delayed satellite sealing method as described in claim 2, characterized in that, The method for correcting the star-sealing start threshold based on the capacitor's state of charge is as follows: When the capacitor is in a high state of charge, the satellite sealing start threshold is increased to terminate energy storage in advance and switch to satellite sealing braking. When the capacitor is in a low state of charge, the satellite sealing start threshold is lowered and the satellite sealing braking is delayed to extend the energy storage time.

4. The delayed satellite sealing method as described in claim 2, characterized in that, The method for correcting the star-sealing start threshold based on the motor winding temperature is as follows: When the winding temperature is in a cold state, reduce the star-sealing start-up threshold to extend the energy storage time. When the winding temperature is in a hot-engine state, the star-sealing start threshold is raised to compensate for the braking force decay. When the winding temperature is in an over-temperature state, the star-sealing start threshold is forcibly raised, energy storage is immediately disengaged and star-sealing braking is initiated.

5. The delayed satellite sealing method as described in claim 2, characterized in that, The method for adjusting the star-sealing start threshold based on load inertia is as follows: When the load inertia is greater than the preset value, the star sealing start threshold is raised to seal the star earlier and shorten the coasting time. When the load inertia is less than the preset value, the star-sealing start threshold is lowered to delay the star-sealing and fully recover the low-speed inertial energy.

6. The delayed satellite sealing method as described in claim 1, characterized in that, The determination of the star-sealing start threshold adopts a combination of offline calibration and real-time correction: the reference star-sealing speed table under different working conditions is pre-calibrated and stored in the MCU program memory. The MCU uses linear interpolation and weighted correction algorithms to fine-tune the reference value obtained from the table based on parameters such as real-time collected speed, capacitor state of charge, and speed drop slope.

7. The delayed satellite sealing method as described in claim 1, characterized in that, During the process of controlling the disconnection of the circuit between the inverter and the three-phase winding of the motor and then controlling the closing of the star-sealing contactor, the contactor action delay is compensated by the speed advance prediction method: the speed drop slope is calculated in real time through the speed decay algorithm, the remaining time for the speed to drop to the star-sealing start threshold is estimated, the total action delay is deducted by the contactor disconnection delay, safety dead time and engagement delay, and the advance command time is calculated and the control command is pre-issued.

8. The delayed satellite sealing method as described in claim 7, characterized in that, While issuing control commands, hardware feedback from the auxiliary contacts of the contactor is introduced for interlocking verification. Only when the contacts of the preceding contactor are detected to be completely open is the control circuit of the subsequent star-sealed contactor allowed to be turned on, ensuring the action sequence of opening before closing.

9. The delayed satellite sealing method as described in claim 1, characterized in that, The energy storage module is a supercapacitor bank, and its energy storage array adopts a hybrid topology structure of series connection followed by parallel connection: multiple individual capacitors are connected in series to increase the operating voltage, and several series capacitor banks are connected in parallel to expand the total energy storage capacity.

10. A permanent magnet synchronous motor system, characterized in that, include: Permanent magnet synchronous motor module, used to realize bidirectional conversion of electrical energy and mechanical energy; The resolver speed detection module is used to detect the speed of the motor rotor and output a speed signal; The MCU main control module is connected to the resolver speed detection module to receive the speed signal and output a first control signal or a second control signal based on the comparison result of the speed signal and the preset star-sealing start threshold. The three-phase bidirectional inverter module has its AC side connected to the three-phase windings of the motor via a first contactor, and its DC side connected to the energy storage module. In response to the first control signal, the three-phase bidirectional inverter module rectifies the three-phase AC power generated by the inertial rotation of the motor into DC power and delivers it to the energy storage module. The high-speed energy storage module is connected to the DC side of the three-phase bidirectional inverter module and is used to store DC power. The low-speed star-sealing circuit includes a star-sealing contactor. The three main contacts of the star-sealing contactor are respectively connected to the U, V, and W phase winding leads of the motor. The star-sealing contactor closes in response to the second control signal, short-circuiting the three phase windings of the motor. The MCU main control module outputs a first control signal when the current speed is higher than the sealing start threshold, and outputs a second control signal to close the sealing contactor when the current speed drops to the sealing start threshold.

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