Variable-frequency energy-saving motor and braking system thereof

Abstract

The invention relates to the technical field of motor manufacturing and power electronic driving control, in particular to a variable-frequency energy-saving motor and a braking system thereof, and the system comprises an integrated magnetic circuit transmission module, an impedance self-adaptive adjustment module and a high-frequency harmonic suppression module; wherein the impedance adjusting module adjusts topology according to the magnetic flux density; when the magnetic flux density is lower than a threshold value, a low-magnetic-resistance path is formed; when the voltage is higher than the threshold value, local magnetic saturation is utilized to block an original path, and magnetic flux is forced to migrate to a deep yoke part; the strategy of changing the space into the linearity effectively compensates magnetic conductivity reduction caused by material saturation, maintains the stator inductance in a linear range, solves the problem of brake failure caused by inductance collapse under high current, avoids over-current shutdown of a frequency converter, and remarkably improves the reliability of the motor under limit brake.

Description

Technical Field

[0001] This invention relates to the fields of motor manufacturing and power electronic drive control technology, specifically to a variable frequency energy-saving motor and its braking system. Background Technology

[0002] In the current industrial application environment of variable frequency motors, the motor system needs to frequently perform rapid braking and variable load driving tasks, and relies on the modulation current provided by the variable frequency driver for control. To achieve this control process, existing solutions typically use conventional asynchronous motors as the actuators. While these motors can operate under normal steady-state conditions, under high-current braking or transient overload conditions, their stator cores, with their fixed magnetic circuit topology, are highly susceptible to magnetic saturation due to magnetic flux density exceeding material limits. This leads to a step collapse of the equivalent inductance of the stator windings. This abrupt change in inductance characteristics causes a sharp increase in the rate of change of current, triggering the inverter's overcurrent protection mechanism, resulting in braking failure or system shutdown. Furthermore, the inherent high-frequency carrier component in the inverter's output current penetrates deep into the core, inducing the skin effect and generating additional eddy current losses and heat, thus limiting the overall energy efficiency of the system. Existing technologies struggle to simultaneously achieve the low magnetic reluctance path required for high-efficiency operation and the anti-saturation impedance characteristics required under extreme conditions at the physical level, and lack effective physical shielding mechanisms against high-frequency harmonics. Therefore, how to improve the adaptive adjustment capability of the motor magnetic circuit to different operating conditions without increasing control complexity to prevent inductor collapse and effectively suppress high-frequency harmonic losses has become an urgent technical problem to be solved. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides a variable frequency energy-saving motor and its braking system. Specifically, the technical solution of the present invention includes: The magnetic circuit transmission module based on the stator core, and the impedance adaptive adjustment module and high-frequency harmonic suppression module integrated on the stator core; The magnetic circuit transmission module is used to construct the main magnetic flux transmission channel of the stator core, carry the excitation magnetic flux input by the external excitation source, and determine the current magnetic flux density of the excitation magnetic flux based on the material properties. The impedance adaptive adjustment module is located in the stator tooth root and yoke connection area of ​​the magnetic circuit transmission module, and is configured to adjust the magnetic circuit topology according to the relationship between the current magnetic flux density and a preset saturation threshold: if the current magnetic flux density is lower than the preset saturation threshold, the impedance adaptive adjustment module keeps the first magnetic circuit channel open and guides the excitation flux through a low magnetic resistance path; if the current magnetic flux density is higher than the preset saturation threshold, the impedance adaptive adjustment module uses the local magnetic saturation effect to block the first magnetic circuit channel and forces the excitation flux to migrate to the second magnetic circuit channel; The high-frequency harmonic suppression module is located in the stator crown near the air gap region of the magnetic circuit transmission module, and is configured to generate an impedance barrier by utilizing the skin effect when receiving the high-frequency carrier component in the excitation flux. Preferably, the impedance adaptive adjustment module specifically includes symmetrically arranged flux overflow slits and a pilot saturation bridge located between the flux overflow slits; The pilot saturation bridge constitutes the first magnetic circuit channel. The minimum cross-sectional width of the pilot saturation bridge is configured to be smaller than the main magnetic circuit width of the magnetic circuit transmission module, so that when the current magnetic flux density reaches the preset saturation threshold, the pilot saturation bridge enters the magnetic saturation state before the main part of the magnetic circuit transmission module. Preferably, the magnetic circuit transmission module is further configured to: when the second magnetic circuit channel is activated, utilize the deep yoke region in the magnetic circuit transmission module that is far from the stator teeth as a detour path for the excitation flux; The effective magnetic path length of the second magnetic path channel is greater than that of the first magnetic path channel, so as to compensate for the equivalent inductance of the stator winding under the local magnetic saturation state. Preferably, the high-frequency harmonic suppression module specifically includes a closed cavity structure; The closed cavity structure is configured such that when a magnetic flux component with a frequency higher than a preset carrier frequency threshold is received, high-frequency eddy currents are induced in the peripheral region of the closed cavity structure, increasing the magnetic resistance to the high-frequency carrier component, thereby shielding the high-frequency carrier component from entering the main body of the magnetic circuit transmission module. Preferably, the impedance adaptive adjustment module is specifically configured to control the inductance reduction rate of the stator winding within a preset linear range by forcing the excitation flux to migrate to the second magnetic circuit channel; The preset linear range is defined as follows: under the condition that the current magnetic flux density increases due to the injection of DC braking current from an external excitation source, the rate of change of the equivalent inductance of the stator winding with the increase of current remains within a preset gradient threshold. The preset gradient threshold is determined based on the stability requirement of maintaining the current waveform without abrupt changes. Preferably, the system further includes an external drive control module, which is configured as follows: Inject the excitation flux into the magnetic circuit transmission module; Monitor the real-time current change rate of the stator winding; If the real-time current change rate is detected to remain within a preset safe range, it is determined that the impedance adaptive adjustment module has successfully switched to the second magnetic circuit channel and maintains or increases the output amplitude of the braking current. Preferably, the external drive control module further includes a braking strategy generation unit, which is specifically configured as follows: Based on the comparison between the real-time current change rate of the stator winding and the preset safety range, the frequency and amplitude of the DC braking component injected into the magnetic circuit transmission module are dynamically adjusted. When the current magnetic flux density fluctuates around the preset saturation threshold, a magnetic flux hysteresis control strategy is executed, that is, a difference is set between the turn-on threshold and the turn-off threshold to smooth the switching process between the first magnetic circuit channel and the second magnetic circuit channel. Preferably, the magnetic circuit transmission module is formed by stacking multiple layers of soft magnetic material sheets, and the impedance adaptive adjustment module and the high-frequency harmonic suppression module are geometric topological features formed by stamping on the soft magnetic material sheets; The preset saturation threshold is a magnetic flux density value determined based on the saturation inflection point of the BH magnetization curve of the soft magnetic material lamination and the minimum cross-sectional area of ​​the pilot saturation bridge. Preferably, a variable frequency energy-saving motor includes a variable frequency drive and a braking system of the variable frequency energy-saving motor according to claim 1, wherein the braking system of the variable frequency energy-saving motor is electrically connected to the variable frequency drive and is used to perform load driving and rapid braking tasks. Compared with the prior art, the present invention has the following beneficial effects: 1. This invention effectively solves the technical problem of braking failure caused by stator inductance collapse under high current conditions by constructing an impedance adaptive adjustment mechanism. The system utilizes the cooperation of a pilot saturation bridge and a magnetic flux overflow slit. When the braking current rises and the magnetic circuit tends to saturate, the local magnetic saturation effect is used to preferentially block the first magnetic circuit channel, forcing the excitation flux to migrate to the deep yoke region away from the stator teeth. This strategy of exchanging space for linearity uses the longer effective magnetic circuit length of the second magnetic circuit channel to compensate for the decrease in permeability caused by material saturation, thereby maintaining the equivalent inductance of the stator winding within the preset linear change range. This physically suppresses the surge in the rate of current change, avoids the inverter from shutting down due to overcurrent protection, and significantly improves the reliability and dynamic response speed of the motor under extreme braking conditions. 2. This invention utilizes a high-frequency harmonic suppression module to physically shield the carrier harmonics of the frequency converter, significantly reducing motor temperature rise and improving energy efficiency. By setting a closed cavity structure near the air gap region of the stator tooth crown, and utilizing the skin effect principle, it specifically targets the high-frequency eddy currents induced by the high-frequency carrier component around the cavity, constructing a high-impedance barrier. This structure is equivalent to setting a physical low-pass filter at the magnetic circuit entrance. Without hindering the transmission of the fundamental magnetic flux to ensure torque output, it effectively prevents high-frequency harmonics from penetrating deep into the iron core, greatly reducing the resulting high-frequency eddy current losses and hysteresis losses, and solving the problem of severe overheating in existing variable frequency motors under high-frequency modulation. 3. This invention ensures the smoothness and determinism of the magnetic circuit mode switching process through deep coupling of physical topology and control strategy; the pilot saturation bridge, as a magnetic fuse, precisely defines the physical critical point of magnetic circuit switching by utilizing the difference in its cross-sectional size, eliminating the chaos of the magnetic circuit state; in conjunction with the magnetic flux hysteresis control strategy of the external drive control module, by setting the difference between the opening and closing thresholds, it effectively prevents frequent switching between the first and second magnetic circuits caused by system disturbances in the critical state; this hardware and software collaborative mechanism not only suppresses electromagnetic noise and torque pulsation, but also ensures the stability of the current closed-loop control system, achieving a smooth and powerful braking experience; 4. This invention adopts an integrated stamping-formed geometric topology structure, realizing complex intelligent magnetic circuit control functions without increasing hardware costs; the impedance adaptive adjustment module and the high-frequency harmonic suppression module are both directly formed by multi-layer soft magnetic material sheets through precision stamping process, without the need for additional sensors, actuators or special expensive magnetic materials; this design is based entirely on the magnetization characteristics of the soft magnetic material itself for passive adjustment, which not only reduces the manufacturing difficulty and cost of the system, but also ensures the consistency of product performance in mass production through standardized geometric parameter constraints, making it easy to promote and apply on a large scale in the industrial field. Attached Figure Description The present invention will be further explained below with reference to the accompanying drawings and embodiments: Figure 1 This is a structural diagram of the system of the present invention. Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. Example 1: Please see Figure 1 A braking system for a variable frequency energy-saving electric motor includes a magnetic circuit transmission module based on a stator core, an impedance adaptive adjustment module and a high-frequency harmonic suppression module integrated on the stator core; wherein, the magnetic circuit transmission module is used to construct the main magnetic flux transmission channel of the stator core, carry the excitation magnetic flux input by an external excitation source, and determine the current magnetic flux density of the excitation magnetic flux based on material properties. The impedance adaptive adjustment module is located in the stator tooth root and yoke connection area of ​​the magnetic circuit transmission module. It is configured to adjust the magnetic circuit topology according to the relationship between the current magnetic flux density and the preset saturation threshold: if the current magnetic flux density is lower than the preset saturation threshold, the impedance adaptive adjustment module keeps the first magnetic circuit channel open and guides the excitation flux through the low magnetic resistance path; if the current magnetic flux density is higher than the preset saturation threshold, the impedance adaptive adjustment module uses the local magnetic saturation effect to block the first magnetic circuit channel and forces the excitation flux to migrate to the second magnetic circuit channel. The high-frequency harmonic suppression module is located in the stator tooth crown near the air gap region of the magnetic circuit transmission module. It is configured to generate an impedance barrier by utilizing the skin effect when it receives the high-frequency carrier component in the excitation flux. This embodiment provides a braking system for a variable frequency energy-saving motor. Its core lies in the innovative micro-geometric topology of the stator core, which physically solves the problem of inductance collapse caused by magnetic circuit saturation under high current braking conditions in traditional asynchronous motors. In this embodiment, the magnetic circuit transmission module refers to the stator core main structure made of laminated soft magnetic materials. Its main function is to construct the main magnetic flux transmission channel of the stator core to carry the excitation flux input from the external excitation source. Based on the BH magnetization characteristics of the material itself, this module determines the current magnetic flux density of the excitation flux under the current current excitation. The impedance adaptive adjustment module is located in the connection area between the stator tooth root and the yoke of the magnetic circuit transmission module. This module was designed to resolve the conflict between high-efficiency operation and the magnetic circuit impedance requirements of powerful braking. It is configured to adjust the impedance according to the current magnetic flux density. With preset saturation threshold The size relationship automatically adjusts the magnetic circuit topology; Specifically, the module operates in two modes: in normal operation mode, if the current magnetic flux density... Below the preset saturation threshold The impedance adaptive adjustment module keeps the first magnetic circuit channel open, guiding the excitation flux smoothly along a low magnetic resistance path to ensure the motor maintains high-efficiency operation; in braking or overload mode, if the current magnetic flux density... Above the preset saturation threshold The impedance adaptive adjustment module utilizes the local magnetic saturation effect to physically cut off or increase the resistance of the first magnetic circuit channel, and forces the excitation flux to migrate its path and enter the second magnetic circuit channel. In addition, the high-frequency harmonic suppression module is located in the stator tooth crown near the air gap region of the magnetic circuit transmission module. It is configured to generate an impedance barrier by utilizing the skin effect when it receives the high-frequency carrier component in the excitation flux, thereby preventing high-frequency harmonics from penetrating deep into the iron core at the source. This embodiment achieves passive intelligent control of the magnetic flux path by constructing such a flux diversion valve structure in situ on the stator core. This design can automatically sense changes in operating conditions without increasing the complexity of external sensors and control algorithms. During normal operation, it maintains low magnetic reluctance to save energy, and during braking, it prevents a sudden drop in inductance through path migration, thereby avoiding inverter malfunctions. Excessive current triggers overcurrent protection, significantly improving the braking reliability and dynamic response speed of the system under extreme conditions. Example 2: In this embodiment, the impedance adaptive adjustment module specifically includes a symmetrically arranged magnetic flux overflow slit and a pilot saturation bridge located between the magnetic flux overflow slits; wherein, the pilot saturation bridge constitutes a first magnetic circuit channel, and the minimum cross-sectional width of the pilot saturation bridge is configured to be smaller than the main magnetic circuit width of the magnetic circuit transmission module, so that when the current magnetic flux density reaches a preset saturation threshold, the pilot saturation bridge enters the magnetic saturation state before the main part of the magnetic circuit transmission module. Based on the above system, this embodiment provides a detailed definition of the specific structure of the impedance adaptive adjustment module. In this embodiment, the flux overflow slit refers to the air gap or non-magnetic filling area formed by stamping at the root of the stator teeth, which defines the boundary of magnetic flux flow. The pilot saturation bridge is the solid iron core connection between the two slits, which constitutes the first magnetic circuit channel mentioned above. To achieve the pilot saturation function, the minimum cross-sectional width of the pilot saturation bridge is... Configured to be significantly smaller than the main magnetic circuit width of the magnetic circuit transmission module This differentiated geometric design allows for the operation of magnetic flux densities that reach a preset saturation threshold. At this time, due to the principle of magnetic flux continuity, the magnetic flux density in the pilot saturation bridge with a smaller cross-sectional area will surge to the saturation point of the material first, thus entering the magnetic saturation state preferentially before the main body of the magnetic circuit transmission module; at this time, the relative permeability of the pilot saturation bridge... The magnetic reluctance drops sharply, approaching the permeability of air, effectively forming a high magnetic reluctance region. This embodiment utilizes a pilot saturation bridge as a magnetic fuse in the magnetic circuit system, precisely defining the critical trigger point for magnetic circuit switching. This structure ensures that a high impedance barrier can be quickly established at the tooth root when most of the stator core is not yet saturated in the initial stage of the braking current rise, creating physical conditions for forcing the magnetic flux into the second channel, ensuring the determinism and repeatability of mode switching, and avoiding control failure caused by chaotic magnetic circuit state. Example 3: The magnetic circuit transmission module is also configured to: when the second magnetic circuit channel is activated, utilize the deep yoke region in the magnetic circuit transmission module that is far from the stator teeth as a detour path for the excitation flux; wherein, the effective magnetic circuit length of the second magnetic circuit channel is greater than the effective magnetic circuit length of the first magnetic circuit channel, so as to compensate for the equivalent inductance of the stator winding under local magnetic saturation. This embodiment further illustrates the specific behavior after the magnetic flux path migration; the magnetic circuit transmission module is also configured to: when the second magnetic circuit channel is activated, that is, after the pilot saturation bridge is saturated, use the deep yoke region in the magnetic circuit transmission module that is far away from the stator teeth as the detour path of the excitation magnetic flux; specifically, when the pilot saturation bridge is blocked, the subsequently added excitation magnetic flux cannot pass through the bridge and is forced to bypass the magnetic flux overflow slit and diffuse into the deeper part of the stator yoke, which constitutes the second magnetic circuit channel; The key feature of this embodiment is that, although the effective magnetic path length of the second magnetic path channel is... Greater than the effective magnetic path length of the first magnetic path channel However, thanks to the unsaturated state of the deep yoke region, its relative permeability is... Much higher than the saturation permeability of the leader saturation bridge According to the physical formula for the definition of inductance: in, This refers to the number of turns in the stator winding. The effective cross-sectional area of ​​the magnetic circuit. The effective permeability of the magnetic circuit material. The effective length of the magnetic circuit is given by... The inductance gain resulting from the value difference covers the influence of the value difference. This increases the inductance loss, thereby compensating for the overall equivalent inductance. This embodiment compensates for the equivalent inductance of the stator winding under local magnetic saturation by using a strategy of exchanging space for linearity. This automatic extension mechanism of the magnetic circuit length ensures that the inductance value of the stator winding does not drop abruptly like that of a normal motor under high-current braking conditions, but maintains a certain degree of linearity, thereby suppressing the rate of change of current di / dt, preventing current runaway, and ensuring the electrical safety of the drive system. Example 4: The high-frequency harmonic suppression module specifically includes a closed cavity structure. The closed cavity structure is configured such that when a magnetic flux component with a frequency higher than the preset carrier frequency threshold is received, high-frequency eddy currents are induced in the surrounding area of ​​the closed cavity structure, increasing the magnetic resistance to the high-frequency carrier component, thereby shielding the high-frequency carrier component from entering the main body of the magnetic circuit transmission module. This embodiment details the structure and principle of the high-frequency harmonic suppression module; the module specifically includes a closed cavity structure, which is typically located at the center or both sides of the stator crown; the closed cavity structure is configured such that when the received frequency is higher than a preset carrier frequency threshold... When the magnetic flux component is high, the closed cavity structure forces the high-frequency magnetic flux to concentrate in the conductor region around the cavity, thereby enhancing the skin effect. Due to the presence of this cavity, part of the eddy current path is cut off, or the high-frequency magnetic flux is forced to induce high-frequency eddy currents in the region around the cavity. According to Lenz's law, these induced eddy currents will generate a reverse magnetic field, which significantly increases the magnetoresistance for the high-frequency carrier component, forming a magnetoresistance barrier for high-frequency signals. However, for the fundamental magnetic flux of 50Hz or 60Hz, due to its large penetration depth, this tiny cavity structure hardly constitutes any obstacle. This embodiment implements a frequency-selective magnetoresistive characteristic and constructs a physical low-pass filter for high-frequency signals. Without affecting the fundamental torque output of the motor, it effectively shields the high-frequency carrier harmonics output by the frequency converter from entering the main body of the stator core, thereby significantly reducing the high-frequency iron loss of the motor, including eddy current loss and hysteresis loss, reducing the motor temperature rise, and achieving the energy-saving goal. Example 5: The impedance adaptive adjustment module is specifically configured as follows: by forcing the excitation flux to migrate to the second magnetic circuit channel, the inductance reduction rate of the stator winding is controlled within a preset linear range. The preset linear range is defined as follows: under the condition that the current flux density increases due to the injection of DC braking current from the external excitation source, the rate of change of the equivalent inductance of the stator winding with the increase of current remains within a preset gradient threshold. The preset gradient threshold is determined based on the stability requirement of maintaining the current waveform without abrupt changes. In this embodiment, the impedance adaptive adjustment module is specifically configured as follows: by forcing the excitation flux to migrate to the second magnetic circuit channel, the inductance reduction rate of the stator winding is controlled within a preset linear range; the preset linear range is defined as: the current magnetic flux density caused by injecting DC braking current from the external excitation source. Under rising operating conditions, the equivalent inductance of the stator winding With current Increased rate of change Maintain at the preset gradient threshold Inside. This embodiment clarifies The specific calculation model is derived based on the physical constraints limiting the rate of change of current ripple, and satisfies dimensional consistency (Henry / Ampere). in, This refers to the DC bus voltage of the frequency converter. For switching cycles; The minimum safe inductance unit for preventing IGBT from overcurrent turn-off is the henry. The value is determined by the system hardware, and the specific calculation formula is as follows: in, The allowable peak current specified in the inverter IGBT module manual. This is the shortest dead time for overcurrent protection response; This is a dimensionless safety factor, typically ranging from 1.2 to 1.5; when the motor's operating ambient temperature is below 40℃ and heat dissipation is good, A value of 1.2 is acceptable; however, when the working environment is harsh or the requirements for braking reliability are extremely high, Use 1.5 to increase the margin; The physical meaning of this formula is: by limiting the rate of decrease of inductance, it ensures that the growth rate of current ripple does not exceed the thermal tolerance of the IGBT. To ensure the above electrical performance indicators To enable implementation through a mechanical structure, this embodiment further establishes constraint equations for the geometric dimensions of the pilot saturation bridge; the system is designed through the physical structural parameters of the connection area between the stator tooth root and the yoke, specifically requiring a specific aspect ratio for the pilot saturation bridge. The following impedance sensitivity constraints must be met: The parameters in the formula are defined as follows: This refers to the number of turns in the stator winding. Vacuum permeability ; The unit for the axial stacking thickness of the stator core is meters. The unit for the maximum design braking current under motor braking conditions is ampere. This is the differential gain of relative permeability of the soft magnetic material at the knee point of its magnetization curve; its definition originates from the point of maximum slope of the material's BH curve, and the calculation formula is:

[0004] For typical non-oriented silicon steel sheets, the maximum value can be obtained by taking the first derivative of the material's BH curve. This value typically falls within the range of... to between; The derivation of this formula is based on the following: According to Ohm's law for magnetic circuits, magnetic reluctance... ,inductance When the leading saturated bridge reaches the saturation knee point, its equivalent inductance is mainly determined by the bridge geometry. To ensure that the rate of change of inductance does not exceed It is necessary to ensure that the magnetic circuit has a sufficient geometric elongation ratio to limit the excessively rapid increase of magnetic flux; the numerator term on the right side of the formula Characterized by the inductance per unit width at the material knee, the denominator term This inequality represents the total allowable change in inductance. From a physical perspective, this ensures that the structural stiffness meets the stability requirements of the electrical control system. This embodiment transforms the abstract magnetic circuit structure design into specific electrical performance indicators, establishing a mapping relationship between physical topology and electrical control stability. By limiting the inductance decay rate, it ensures that the current closed-loop control system of the frequency converter can operate stably, avoiding PI regulator saturation or oscillation caused by inductance abrupt changes, thereby achieving a smooth and powerful braking process. Example 6: The system also includes an external drive control module, which is configured to: inject excitation flux into the magnetic circuit transmission module; monitor the real-time current change rate of the stator winding; if the real-time current change rate is detected to remain within a preset safe range, determine that the impedance adaptive adjustment module has successfully switched to the second magnetic circuit channel, and maintain or increase the output amplitude of the braking current; the external drive control module also includes a braking strategy generation unit, which is specifically configured to: dynamically adjust the frequency and amplitude of the DC braking component injected into the magnetic circuit transmission module based on the comparison result between the real-time current change rate of the stator winding and the preset safe range; when the current magnetic flux density fluctuates near a preset saturation threshold, execute a magnetic flux hysteresis control strategy, that is, set a difference between the turn-on threshold and the turn-off threshold to smooth the switching process between the first magnetic circuit channel and the second magnetic circuit channel. This embodiment introduces an external drive control module, realizing the synergy between hardware structure and software control; this module is configured to inject excitation flux into the magnetic circuit transmission module and execute the following logic: the system monitors the real-time current change rate of the stator winding in real time. ; Specifically, the external drive control module is configured with a cutoff frequency of The low-pass filter, the cutoff frequency Configured to match the inverter switching frequency satisfy The constraint relationship is designed to effectively filter out PWM switching noise while retaining the braking current. The system monitors the dynamic changes of the stator current; it filters the collected stator current and then calculates the difference between the filtered and filtered currents as the real-time current change rate; if the filtered real-time current change rate is detected to remain within a preset safe range... If the impedance adaptive adjustment module has successfully switched to the second magnetic circuit channel, it is determined that the physical anti-collapse mechanism has taken effect. Based on the judgment result, the system maintains or increases the output amplitude of the braking current to maximize the braking torque; furthermore, the external drive control module also includes a braking strategy generation unit; this unit is configured to dynamically adjust the frequency and amplitude of the DC braking component injected into the magnetic circuit transmission module based on the comparison result of the real-time current change rate of the stator winding and the preset safety range; the specific dynamic adjustment algorithm is as follows: calculate the real-time current change rate. With respect to the center value of the preset safety interval deviation Here, the deviation between the target value and the actual value is used to ensure the stability of the negative feedback control. An incremental PI algorithm is used to adjust the duty cycle of the braking voltage. : in, This represents the duty cycle of the current control period. The duty cycle of the previous control cycle. The deviation value for the kth sampling period. This is the deviation value at the previous sampling time. The preset proportional and integral gain coefficients; specifically, when the current magnetic flux density is at a preset saturation threshold. When there are fluctuations in the vicinity, a flux hysteresis control strategy is implemented; that is, an activation threshold is set. With the shutdown threshold There is a difference; the specific formula for calculating the difference is: in, This is the anti-interference coefficient, dimensionless. To prevent PWM switching noise from falsely triggering magnetic circuit switching, its typical value ranges from 1.05 to 1.15. The allowable current ripple amplitude is typically set to 5% to 10% of the rated current; This is the current real-time estimated equivalent inductance; this value is obtained by the external drive control module through real-time voltage sampling. With the rate of change of current The calculation shows that, ; This refers to the number of turns in the winding. This is the effective cross-sectional area of ​​the iron core, which is approximately equal to the width of the main magnetic circuit defined in Example 2. Multiply by the stacking thickness ; This strategy uses hysteresis at the software level, combined with magnetic saturation characteristics at the hardware level, to smooth the switching process between the first and second magnetic circuit channels. In practice, the external drive control module utilizes pre-stored stator core BH magnetization curve data to calculate the magnetic flux density threshold. and Real-time mapping to the corresponding current control threshold and This allows for the implementation of a flux hysteresis strategy at the current closed-loop control level, ensuring that the controller can directly respond to changes in the magnetic circuit state by adjusting the current output. This embodiment constructs a closed-loop feedback mechanism of hardware and software, realizing deep coupling between physical mechanism and control logic. The hardware provides the physical basis for anti-saturation, while the software confirms whether the physical mechanism is effective by monitoring the hardware response and optimizes the control strategy accordingly. In particular, the introduction of hysteresis control strategy effectively prevents electromagnetic noise and torque pulsation caused by frequent switching of magnetic circuit in critical state, ensuring the smoothness of braking process. Example 7: In this embodiment, the magnetic circuit transmission module is formed by stacking multiple layers of soft magnetic material laminations, and the impedance adaptive adjustment module and the high-frequency harmonic suppression module are geometric topological features formed by stamping on the soft magnetic material laminations; the preset saturation threshold is a magnetic flux density value determined based on the saturation inflection point of the BH magnetization curve of the soft magnetic material laminations and the minimum cross-sectional area of ​​the leading saturation bridge.

[0005] This embodiment details the system's manufacturing process and parameter determination method; the magnetic circuit transmission module is formed by stacking multiple layers of soft magnetic material laminations; the impedance adaptive adjustment module and the high-frequency harmonic suppression module are not post-processing but are geometric topological features formed in one step on the soft magnetic material laminations through a precision stamping process; a preset saturation threshold is included. It is not set arbitrarily, but is based on the saturation inflection point of the BH magnetization curve of the soft magnetic material lamination and the minimum cross-sectional area of ​​the leader saturation bridge. A defined magnetic flux density value; here, the minimum cross-sectional area. Minimum cross-sectional width of the pilot saturation bridge in Example 2 Thickness of the stator core The product is determined, i.e., the calculation formula is: Specifically, when the total magnetic flux flowing through the stator teeth causes the magnetic flux density to reach the saturation magnetic induction intensity of the material, the corresponding total magnetic flux density is the threshold. This embodiment ensures low cost and manufacturability of the solution, and verifies the feasibility of complex magnetic circuit topology in industrial production. By utilizing mature stamping technology, the above-mentioned complex functions are achieved without adding extra parts and assembly processes. At the same time, the parameter design method based on material physical properties ensures the consistency of motor performance in different batches and reduces the dependence on special and expensive magnetic materials. Example 8: A variable frequency energy-saving motor includes a variable frequency drive and a braking system of the variable frequency energy-saving motor according to any of the above embodiments. The braking system of the variable frequency energy-saving motor is electrically connected to the variable frequency drive and is used to perform load driving and rapid braking tasks. This embodiment provides a variable frequency energy-saving motor, which includes a variable frequency driver and a braking system of the variable frequency energy-saving motor of any of the above embodiments; the braking system of the variable frequency energy-saving motor, i.e., the stator part, is electrically connected to the variable frequency driver; in this embodiment, the variable frequency driver not only serves as a power source, but also as a carrier of the above-mentioned external drive control module; the motor system is used to perform load driving and rapid braking tasks, and is particularly suitable for industrial applications such as elevators, conveyor belts, and packaging machinery that require frequent starts and stops and have high energy efficiency requirements; This embodiment provides a system-level solution that breaks down the barriers between motor design and frequency conversion control strategy. The motor has excellent energy efficiency during normal operation and benefits from high-frequency harmonic suppression. It also has braking capability that surpasses that of ordinary motors of the same class during braking and benefits from impedance adaptive adjustment. This solves the industry pain point that ordinary asynchronous motors cannot adapt to high-performance frequency conversion braking in the prior art and improves the overall efficiency of the entire power system. It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A braking system for a variable frequency energy-saving electric motor, characterized in that, It includes a magnetic circuit transmission module based on the stator core, as well as an impedance adaptive adjustment module and a high-frequency harmonic suppression module integrated on the stator core; The magnetic circuit transmission module is used to construct the main magnetic flux transmission channel of the stator core, carry the excitation magnetic flux input by the external excitation source, and determine the current magnetic flux density of the excitation magnetic flux based on the material properties. The impedance adaptive adjustment module is located in the stator tooth root and yoke connection area of ​​the magnetic circuit transmission module, and is configured to adjust the magnetic circuit topology according to the relationship between the current magnetic flux density and a preset saturation threshold: if the current magnetic flux density is lower than the preset saturation threshold, the impedance adaptive adjustment module keeps the first magnetic circuit channel open and guides the excitation flux through a low magnetic resistance path; if the current magnetic flux density is higher than the preset saturation threshold, the impedance adaptive adjustment module uses the local magnetic saturation effect to block the first magnetic circuit channel and forces the excitation flux to migrate to the second magnetic circuit channel; The high-frequency harmonic suppression module is located in the stator crown near the air gap region of the magnetic circuit transmission module, and is configured to generate an impedance barrier by utilizing the skin effect when receiving the high-frequency carrier component in the excitation flux.

2. The braking system of the variable frequency energy-saving motor according to claim 1, characterized in that, The impedance adaptive adjustment module specifically includes symmetrically arranged flux overflow slits and a pilot saturation bridge located between the flux overflow slits; The pilot saturation bridge constitutes the first magnetic circuit channel. The minimum cross-sectional width of the pilot saturation bridge is configured to be smaller than the main magnetic circuit width of the magnetic circuit transmission module, so that when the current magnetic flux density reaches the preset saturation threshold, the pilot saturation bridge enters the magnetic saturation state before the main part of the magnetic circuit transmission module.

3. The braking system of the variable frequency energy-saving motor according to claim 1, characterized in that, The magnetic circuit transmission module is further configured to: when the second magnetic circuit channel is activated, utilize the deep yoke region in the magnetic circuit transmission module that is far from the stator teeth as a detour path for the excitation flux; The effective magnetic path length of the second magnetic path channel is greater than that of the first magnetic path channel, so as to compensate for the equivalent inductance of the stator winding under the local magnetic saturation state.

4. The braking system of the variable frequency energy-saving motor according to any one of claims 1-3, characterized in that, The high-frequency harmonic suppression module specifically includes a closed cavity structure; The closed cavity structure is configured such that when a magnetic flux component with a frequency higher than a preset carrier frequency threshold is received, high-frequency eddy currents are induced in the peripheral region of the closed cavity structure, increasing the magnetic resistance to the high-frequency carrier component, thereby shielding the high-frequency carrier component from entering the main body of the magnetic circuit transmission module.

5. The braking system of the variable frequency energy-saving motor according to claim 3, characterized in that, The impedance adaptive adjustment module is specifically configured to control the inductance reduction rate of the stator winding within a preset linear range by forcing the excitation flux to migrate to the second magnetic circuit channel. The preset linear range is defined as follows: under the condition that the current magnetic flux density increases due to the injection of DC braking current from an external excitation source, the rate of change of the equivalent inductance of the stator winding with the increase of current remains within a preset gradient threshold. The preset gradient threshold is determined based on the stability requirement of maintaining the current waveform without abrupt changes.

6. The braking system of the variable frequency energy-saving motor according to claim 1, characterized in that, The system also includes an external drive control module, which is configured as follows: Inject the excitation flux into the magnetic circuit transmission module; Monitor the real-time current change rate of the stator winding; If the real-time current change rate is detected to remain within a preset safe range, it is determined that the impedance adaptive adjustment module has successfully switched to the second magnetic circuit channel and maintains or increases the output amplitude of the braking current.

7. The braking system of the variable frequency energy-saving motor according to claim 6, characterized in that, The external drive control module further includes a braking strategy generation unit, which is specifically configured as follows: Based on the comparison between the real-time current change rate of the stator winding and the preset safety range, the frequency and amplitude of the DC braking component injected into the magnetic circuit transmission module are dynamically adjusted. When the current magnetic flux density fluctuates around the preset saturation threshold, a magnetic flux hysteresis control strategy is executed, that is, a difference is set between the turn-on threshold and the turn-off threshold to smooth the switching process between the first magnetic circuit channel and the second magnetic circuit channel.

8. The braking system of the variable frequency energy-saving motor according to claim 1, characterized in that, The magnetic circuit transmission module is formed by stacking multiple layers of soft magnetic material sheets, and the impedance adaptive adjustment module and the high-frequency harmonic suppression module are geometric topological features formed by stamping on the soft magnetic material sheets. The preset saturation threshold is a magnetic flux density value determined based on the saturation inflection point of the BH magnetization curve of the soft magnetic material lamination and the minimum cross-sectional area of ​​the pilot saturation bridge.

9. A variable frequency energy-saving electric motor, characterized in that, The invention includes a variable frequency drive and a braking system for the variable frequency energy-saving motor as described in claim 1, wherein the braking system of the variable frequency energy-saving motor is electrically connected to the variable frequency drive and is used to perform load driving and rapid braking tasks.

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