822 results about "Counter-electromotive force" patented technology

The invention discloses a hybrid effective flux linkage observer and a permanent magnet synchronous motor control method, device and system. The method comprises the following steps: carrying out Clarke conversion on an obtained three-phase current of the permanent magnet synchronous motor to obtain a current in a static coordinate system, and carrying out park conversion based on rotor position information to obtain a current in a synchronous rotating coordinate system; the effective flux linkage of the permanent magnet synchronous motor is obtained through the hybrid effective flux linkage observer; on the basis of the obtained effective flux linkage of the permanent magnet synchronous motor, dead-zone compensation voltage is obtained through self-adaptive gain dead-zone compensation calculation based on back electromotive force reconstruction, and the rotating speed and the rotor position of the permanent magnet synchronous motor are obtained through phase-locked loop calculation; according to the rotating speed and the rotor position of the permanent magnet synchronous motor, the current under the synchronous rotating coordinate system, the dead zone compensation voltage and the obtained reference rotating speed and reference current, the reference voltage of the motor at the k moment is obtained through a rotating speed loop and a current loop and used for achieving low-speed position-sensorless control over the permanent magnet synchronous motor.

The invention relates to the field of intelligent control of electromagnetic appliances, and provides a control method and system for online fault diagnosis of a magnetic latching relay, and the method comprises the steps: responding to an external control instruction, collecting real-time bus voltage and real-time environment temperature data, constructing environment state characteristics through a magnetothermal coupling algorithm, and generating an initial PWM drive duty ratio; pulse modulation voltage is loaded, a current sampling sequence is collected, a current change rate sequence is obtained through moving average filtering and electromechanical coupling decoupling, extreme value searching is executed to extract counter electromotive force distortion characteristics, and a dynamic current sequential sequence is generated; a fusion input tensor is constructed, armature state probability distribution is output through a gating circulation unit, and a real-time energy compensation instruction is generated in a displacement interval before closing; and according to the real-time energy compensation instruction, respectively generating an enhanced driving waveform, a delayed driving waveform or a vibration driving waveform. According to the method, multi-mode physical characteristic perception and depth time sequence deduction are fused, and online fault diagnosis and active intervention closed loop of the magnetic latching relay are realized.

The invention discloses an axial winding complementary type hybrid excitation high-speed magnetic flux reverse motor, and belongs to the technical field of power generation, power transformation or power distribution. The motor comprises a six-slot stator iron core, a four-tooth rotor iron core, a set of annular winding serving as an excitation winding and a set of concentrated winding serving as an armature winding, permanent magnet groups are attached to the inner surface of the tooth part of the stator core, two groups of axial permanent magnets are opposite in polarity, and two groups of circumferential permanent magnets are opposite in polarity; and the rotor iron core is formed by laminating a plurality of rotor iron core sections which have a mechanical angle of 45 degrees in the axial direction. The motor has the magnetic field adjusting capacity and has the advantages of being small in flux linkage, counter electromotive force sine, cogging torque and torque fluctuation, extra rising voltage caused by strong armature reaction during high-speed operation can be reduced through flux weakening, torque during low-speed operation can be improved through flux increasing, and due to the fact that the number of poles is small, loss is small during high-speed and high-frequency operation, and the motor is high in reliability. Compared with other magnetic flux reverse motors, the magnetic flux reverse motor is more suitable for high-speed operation.

The invention discloses a stator double-permanent-magnet flux reverse motor, and belongs to the technical field of motors. The motor comprises a stator, a rotor, tangential permanent magnets, Halbach array permanent magnets and windings, the stator is of a double-salient-pole structure formed by combining T-shaped stator iron core blocks. The rotor and the stator are coaxially assembled, and an air gap is reserved between the rotor and the stator. The tangential permanent magnets are installed between the stator iron core blocks and magnetized in the tangential direction, and the adjacent directions are opposite. The Halbach permanent magnets are arranged at the openings of the stator slots, so that the Halbach permanent magnets have a magnetism gathering effect and can provide relatively high air gap flux density; the winding adopts a double-layer centralized design and is embedded into a stator slot; the tangential permanent magnets and the Halbach permanent magnets form a parallel magnetic circuit, and the air gap flux density and the torque density are improved through magnetic field superposition; the number of winding pole pairs meets a specific formula, and the motor structure can be optimized through a finite element method. Compared with a traditional motor, the motor has higher air gap flux density, no-load back electromotive force and torque, lower torque pulsation and a higher power factor, and the electromagnetic performance and the operation stability are remarkably improved.

The invention discloses a motor control method and device, a motor, an air compressor, a storage medium and a computer program product, and the method comprises the steps: carrying out the processing of the components of the stator voltage of the motor on the alpha and beta axes and the components of the stator current of the motor on the alpha and beta axes through a preset sliding mode observer module, and carrying out the control of the motor; the components of the counter electromotive force estimated value of the motor on the alpha and beta axes are obtained; based on the components of the back electromotive force estimation value of the motor on the alpha axis and the beta axis, after a preset phase-locked loop module and a preset staged angle compensation module are used for processing, a rotor electrical angular speed estimation value of the motor and a rotor electrical angular position estimation value of the motor are obtained, and control over the motor is achieved. According to the scheme, by combining the sliding mode observer module, the phase-locked loop module and the staged angle compensation module, the rotor electrical angular velocity estimation value and the rotor electrical angular position estimation value of the motor are determined, sensorless control over the motor is achieved, and the control performance of the motor is improved.

The invention discloses a BLDC (brushless direct current) driving parameter self-tuning embedded system and method for multiple equipment types, and the method comprises the steps: constructing a BLDC unified mathematical model containing an electromagnetic torque equation, a back electromotive force equation and a mechanical motion equation, and building a nonlinear mapping relation library of motor type identification codes and a key electrical parameter set; a predefined multi-mode excitation signal sequence is injected into the to-be-driven BLDC motor, dynamic response data are synchronously collected, and the dynamic response data are used for representing the characteristics of the key electrical parameter set; based on collected dynamic response data, equivalent inductance and equivalent resistance in a key electrical parameter set are decoupled and extracted through a frequency domain impedance analysis method, and meanwhile, a counter electromotive force coefficient and rotational inertia in the key electrical parameter set are identified by combining time domain counter electromotive force zero crossing point detection with rotating speed differential operation. Based on a motor fingerprint feature library and a fuzzy adaptive architecture, multi-model debugging-free plug-and-play is realized, and stable control performance is maintained under a dynamic working condition.

The invention provides a control method and system of a permanent magnet synchronous motor, computer equipment and a medium, and belongs to the field of motor control, and the method comprises the steps: obtaining stator current and voltage signals of the permanent magnet synchronous motor; constructing and operating a second-order sliding mode observer to output a stator current observation value; based on the current observation error and the change rate thereof, constructing a mixed sliding mode surface containing a linear term and a nonsingular terminal term, and designing a sliding mode control law; the control law is fed back to an observer to correct the observation process, and meanwhile two-phase observation counter electromotive force which is free of buffeting and does not need low-pass filtering is directly exported; closed-loop demodulation is carried out on the back electromotive force through a phase-locked loop, estimated values of the rotor position and the rotating speed are extracted, and finally position-sensorless vector control of the permanent magnet synchronous motor is achieved. According to the method, the buffeting phenomenon of a traditional sliding-mode observer is inhibited, a low-pass filter is avoided, phase lag is eliminated, and the estimation precision and the dynamic response performance of the system are improved.

The invention discloses a high-speed brushless direct current motor torque ripple suppression method, device and equipment and a storage medium, and belongs to the technical field of motor control. The method comprises three steps of adaptive harmonic suppression processing, phase compensation angle calculation and dynamic phase compensation. According to the invention, the center frequency is dynamically adjusted through the adaptive harmonic wave notch filter, the dominant harmonic component is inhibited in real time, and in combination with cascade delay signal elimination, 6k fixed subharmonics are filtered through the CDSC filter, so that a fundamental wave current signal is obtained; park transformation is carried out on the fundamental wave current based on an FOC algorithm, a PI controller is utilized to generate a phase delay angle according to a d-axis current error, and then a reference current compensation module dynamically compensates a current reference value to ensure phase synchronization of phase current and back electromotive force. Compared with the prior art, additional hardware equipment is not needed, and the torque ripple of the BLDC is reduced.

The present invention discloses a method, device, equipment, and medium for suppressing motor back-electromotive force harmonics. The method includes: obtaining the three-way back-electromotive force of a synchronous motor; transforming the three-way back-electromotive force to obtain a direct-axis back-electromotive force and a quadrature-axis back-electromotive force; performing a Fourier transform on the quadrature-axis back-electromotive force and extracting the amplitude, frequency, and initial phase of each order harmonic of the quadrature-axis back-electromotive force; reconstructing each order harmonic of the quadrature-axis current based on the amplitude, frequency, and initial phase of each order harmonic of the quadrature-axis back-electromotive force; superimposing each order harmonic of the quadrature-axis current to obtain a reconstructed quadrature-axis current; and injecting the reconstructed quadrature-axis current into the quadrature-axis back-electromotive force to obtain the original torque representation value. This solution achieves suppression of motor back-electromotive force harmonics, with excellent harmonic suppression effect.

A controller for a permanent magnet synchronous motor includes a first control loop having a first filter. The first filter has a back-EMF voltage vector input, a magnetic flux vector output with a constant phase shift that is independent of motor speed, and an amplitude response that is inversely proportional to rotor electrical frequency. The first control loop is configured to: generate an adjusted magnetic flux vector from the magnetic flux vector output by the first filter and compensate for the constant phase shift introduced by the first filter; estimate the rotor electrical frequency from the adjusted magnetic flux vector; and feedback a filtered version of the rotor electrical frequency estimate to the first filter as an estimation of the rotor electrical frequency.

The invention discloses a humanoid robot joint motor control method with model prediction control, and relates to the technical field of robot motion control. The method is used for solving the problems of control instruction infeasibility and model disturbance caused by voltage saturation during high-speed motion. An error state space model of a joint motor system is established, and non-linear terms such as gravity are used as nominal feed-forward quantities for stripping; then, the rotating speed of the motor and the bus voltage of the driver are collected in real time, the back electromotive force is calculated, and the voltage margin is mapped into a dynamic torque physical limit value at the current moment; and meanwhile, estimating an unmodeled lumped disturbance value of the model by using an extended state observer. And finally, taking the dynamic limit as a real-time inequality constraint, introducing a disturbance value correction prediction equation, constructing and solving a quadratic programming problem, extracting an optimal compensation torque, superposing the optimal compensation torque with an inverse dynamic feedforward torque, and converting the superposed torque into a current signal to drive a motor, thereby realizing high-dynamic and high-precision robust control under the physical boundary constraint.

The invention belongs to the technical field of motor control, and particularly relates to a motor three-phase counter electromotive force phase sequence detection circuit and a running direction judgment device. The phase sequence detection circuit comprises a comparison circuit and further comprises a tachogenerator coaxially connected with the motor to be detected, and the output end of the tachogenerator is electrically connected with the input end of the comparison circuit so that the phase sequence of the three-phase counter electromotive force of the motor to be detected can be obtained through the three-phase voltage output by the tachogenerator through the comparison circuit. The three-phase counter electromotive force of the to-be-tested motor is directly detected through the tachogenerator coaxially connected with the to-be-tested motor. The rotor of the tachogenerator rotates along with the rotation of the motor to be tested, and the rotor of the tachogenerator cuts magnetic lines in the operation process, thereby generating the three-phase counter electromotive force of the motor to be tested. The technical problem that in the prior art, when ground voltage detection is not accurate due to external interference, detected counter electromotive force is not accurate, and then the motor control effect is affected is solved.

The invention relates to an optimal design method of a wind power controllable magnetic gearbox, and belongs to the field of wind power. The controllable magnetic gear box comprises an inner rotor, an outer rotor, a magnetism adjusting ring and a stator, an inner rotor average torque and torque pulsation, a stator no-load back electromotive force amplitude and a distortion rate are selected as optimization targets, ten parameters such as inner and outer rotor iron core thicknesses, a permanent magnet thickness, a magnetic adjusting ring thickness, a stator iron core outer radius and a stator winding turn number are selected as design variables to be optimized, an LHS experiment is carried out, and a BPNN proxy model is established and trained; performing Sobol 'global sensitivity analysis on the trained agent model to screen out key design variables to be optimized; optimizing the key design variables to be optimized by adopting NSGA-II to obtain an optimal solution set; and the optimal solution set is evaluated by adopting TOPSIS, and a group of optimal design variables are accurately selected, so that the optimization target is optimal. According to the method, the optimization precision and efficiency can be remarkably improved, and the purposes of reducing the cost and improving the performance are achieved.

An electrically powered aircraft is configured to check the health of its motors by determining a flux linkage associated with each of the motors. The flux linkage may be determined by measuring the back-EMF of stator coils of the motor. The flux linkage may be measured while the motor is not powered or may be estimated when the motor is in use. The flux linkage of a motor may be compared to a corresponding threshold value to assess whether the magnet(s) of the motor have degraded to a point at which they pose safety concerns. The flux linkage values may also be used to project when the motor needs to be maintained and / or replaced. The flux linkage value of a motor may be displayed, along with historical flux linkage values for that motor, to show a magnitude of demagnetization of the magnet(s) of the motor.

The invention discloses an irreversible demagnetization risk prediction method for a permanent magnet synchronous motor, and the method comprises the steps: constructing a relation model between the temperature of a magnetic block and the no-load counter electromotive force of the motor, and calculating a target no-load counter electromotive force at a highest allowable environment temperature through employing a reference no-load counter electromotive force. According to the method, a complete physical relation chain from the magnetic block temperature to the residual magnetism density and then to the motor no-load magnetic flux and the motor no-load counter electromotive force is considered, the motor no-load counter electromotive force at the highest allowable environment temperature is obtained based on the relation model by using the reference no-load counter electromotive force to serve as the target no-load counter electromotive force, and accurate assessment of the irreversible demagnetization risk is achieved. In the running process of the motor, the no-load counter electromotive force of the motor is monitored when the motor driving current is zero and the motor is in the no-load running state every time, when the difference value between the target no-load counter electromotive force and the monitored no-load counter electromotive force exceeds a preset threshold value Eh1, early warning is triggered, and when the difference value exceeds Eh2, shutdown protection is triggered; risk monitoring of the magnetic performance state is achieved by indirectly monitoring the no-load back electromotive force.

The utility model provides a back electromotive force electric energy recovery circuit of an unmanned aerial vehicle and the unmanned aerial vehicle. The multiple battery voltages are combined through the combining output circuit to supply power to the load, when back electromotive force exists due to deceleration of the unmanned aerial vehicle, the multiple battery voltages are detected through the comparison circuit, and if the back electromotive force voltage is larger than the voltage of each battery, at least one reverse charging circuit is opened to charge the battery. According to the embodiment, when the multiple batteries supply power to the unmanned aerial vehicle, mutual charging between the batteries can be prevented, counter electromotive force electric energy generated when the motor slows down can be absorbed through the batteries, uninterruptible power supply of the unmanned aerial vehicle can be achieved through hot plugging of the batteries when the unmanned aerial vehicle is in a standby state, and the unmanned aerial vehicle is convenient to use. The time for starting up, shutdown and initialization of the unmanned aerial vehicle due to battery replacement is shortened, and the working efficiency of the unmanned aerial vehicle is improved.

The control method comprises the following steps that A, an angle relation is extracted from counter electromotive force, the actual position of a rotor and the current rotating speed of the fan are obtained through phase-locked loop calculation, and the forward and reverse wind state of the fan is judged according to the positive or negative value of the current rotating speed value of the fan; and B, the starting mode of the air conditioner fan is controlled according to the clockwise and counterclockwise wind of the fan, the current rotating speed of the fan and the actual position of the rotor judged in the step A. Different starting control modes are selected by detecting the current forward and reverse wind states and the rotating speed of the draught fan, and the starting reliability of the draught fan is improved. Compared with forward and reverse wind judgment of a fan provided with a sensor, the hardware cost is reduced, and the structure is simplified; compared with some open-loop algorithms, the angle is calculated through closed-loop control of the phase-locked loop, and the anti-interference capability and the angle following real-time performance are better.

The invention discloses a pumping unit disc type permanent magnet motor multi-objective parameter optimization method, which relates to the technical field of motor design and optimization, and comprises the following steps: pre-establishing a multi-physical field coupling simulation model, constructing a disc type permanent magnet motor electromagnetic and thermal performance simulation model based on Motor-CAD and Maxwell software, and completing no-load, load and thermal performance tests of the motor. According to the method, the multi-physical field coupling simulation model is established in advance, so that comprehensive coupling analysis of electromagnetic and thermal performance of the disc type permanent magnet motor is realized, and high-precision data support is provided for multi-objective optimization; key structure parameters such as air gap length, slot opening width and the like are scientifically selected as optimization objects, maximization of motor efficiency and minimization of cogging torque are taken as core targets, and meanwhile, constraint requirements of output torque, back electromotive force and structure size are strictly adherent to each other, so that the pain point that multiple performances are difficult to consider at the same time in traditional optimization is effectively solved.

The invention discloses a dual three-phase permanent magnet synchronous motor harmonic suppression method based on virtual back electromotive force identification, and the method comprises the following steps: S1, building a driving system model of a DTP-PMSM; s2, constructing a harmonic model of the DTP-PMSM, analytically decomposing the nonlinear characteristic and the non-sinusoidal counter electromotive force of the inverter into dq and dqz subspaces, introducing the concept of virtual harmonic counter electromotive force, and unifying the nonlinearity of the inverter, the space harmonic counter electromotive force and cross coupling terms related to harmonic current into a single expression form; and S3, developing an identification principle based on current mapping, including amplitude and phase estimation, gain design and delay compensation, so as to estimate the amplitude and phase deviation of the virtual harmonic back electromotive force on line to realize harmonic suppression and avoid a complex algorithm and a large amount of parameter adjustment. According to the method, the operation effect is good in a wide rotating speed range, and meanwhile complex algorithms and a large amount of parameter adjustment are avoided.

The invention discloses an energy-saving operation control method and system for a permanent magnet direct current pump motor, and relates to the technical field of motor control, and the method comprises the steps: collecting a first drive current signal and a back electromotive force signal of the permanent magnet direct current pump motor; if a periodic peak and an electrical angle concentration phenomenon exist in the first driving current signal, performing quality evaluation on the back electromotive force signal to obtain back electromotive force credibility; if the back electromotive force credibility is greater than a preset credibility threshold value, applying operation parameter disturbance to the permanent magnet direct current pump motor; acquiring a second driving current signal of the permanent magnet direct current pump motor; performing disturbance response feature extraction on the permanent magnet direct current pump motor to obtain disturbance response features; identifying a disturbance source; and adjusting the operation strategy of the permanent magnet direct current pump motor to control the motor to operate. According to the method, the disturbance source can be recognized by combining the operation parameter disturbance and the disturbance response characteristics, the operation strategy is adjusted, motor operation control is achieved, and accuracy and reliability are improved.

A mechanical timepiece includes: a hairspring; a permanent magnet; a soft magnetic core; a control circuit for performing rate adjustment based on a counter-electromotive voltage caused in a coil by a motion of the permanent magnet accompanying a forward direction motion and a reverse direction motion of the balance wheel. The permanent magnet is arranged so that, under a state in which the hairspring is brought to an equilibrium length, a direction of magnetization is directed to the first end portion side or the second end portion side.

The invention relates to the technical field of motor driving, and discloses a motor driving circuit system of a high-speed air duct, which comprises a motor driving circuit composed of three half-bridge driving chips, and each chip is integrated with two high-voltage MOSFETs and a high-voltage grid driver to form a three-phase full-bridge driving topology; the current detection circuit comprises a single sampling resistor and a differential amplification circuit and is used for acquiring a motor phase current signal; the overcurrent comparison circuit comprises a high-speed comparator; a master control circuit; a back electromotive force detection circuit; an EMC filtering and power supply circuit; and a voltage detection circuit. High integration of a driving circuit is realized through a built-in half-bridge chip packaged by double MOSFETs and a driver QFN77, each chip integrates a temperature detection function and forms a three-phase full-bridge topology, the area of a PCB is reduced, the complete driving protection function is reserved, meanwhile, the layout complexity is remarkably reduced, and the requirements of portable equipment for compact space and low cost are met.

The utility model discloses a motor and a compressor, the compressor comprises a motor, and the motor comprises a rotor, a permanent magnet and a stator. The rotor is provided with a plurality of first through holes arranged at intervals in the circumferential direction of the rotor and a plurality of magnet grooves arranged at intervals in the circumferential direction of the rotor, the first through holes and the magnet grooves are arranged in a penetrating mode in the axis direction of the rotor, and the first through holes extend by a preset length in the circumferential direction of the rotor. The magnet grooves are formed in the sides, close to the outer circumferential face of the rotor, of the first through holes and communicate with the first through holes, all the magnet grooves extend in the radial direction of the rotor, the two ends, in the circumferential direction of the rotor, of one first through hole communicate with one magnet groove correspondingly, and the two magnet grooves communicating with the same first through hole are symmetrically formed along the center line of the first through hole. The multiple permanent magnets are embedded in the multiple magnet grooves in a one-to-one correspondence mode. The stator is provided with a second through hole, and the stator sleeves the periphery of the rotor through the second through hole. The problem of poor back electromotive force sine of the motor in the prior art is solved.

The invention provides a motor driving method and device, electronic equipment and a storage medium. The method comprises the following steps: determining a driving signal parameter of a driving signal corresponding to a current vibration period, and determining a driving stage of the current vibration period and a detection stage of a continuous driving stage; in the driving stage of the current vibration period, driving the motor to vibrate according to the driving signal, and in the detection stage of the current vibration period, obtaining the back electromotive force of the motor corresponding to the current vibration period; and according to the back electromotive force of the motor corresponding to the current vibration period, obtaining the driving signal frequency of the to-be-executed vibration period, and obtaining the driving stage of the to-be-executed vibration period and the detection stage following the driving stage. Through a real-time asynchronous closed-loop control mode, dynamic adjustment of driving signal parameters is realized, and the stability of motor vibration can be maintained when an external load changes.

The invention relates to a motor control circuit, method and module, a storage medium, a controller and a vehicle, and the motor control circuit comprises a detection circuit and a protection circuit. The detection circuit is used for detecting a detection parameter generated by the counter electromotive force generated by the motor; and the protection circuit is used for disconnecting the motor and the motor driving circuit when the detection parameter meets a first condition, so as to at least partially solve the problem that the ASC scheme cannot be directly executed, and the bus capacitor and the battery pack are reversely charged by overhigh counter electromotive force through the fly-wheel diode of the switching tube.

The invention discloses an SMO-EKF brushless direct current motor position-free control method based on SBA-GWO double-layer optimization, SMO adopts sliding mode surface gradient-rotating speed double-factor segmented gain, and an improved SBA-GWO algorithm is combined with a global exploration mechanism of a stingless bee algorithm and a group cooperation characteristic of a grey wolf optimization algorithm. An elite initialization strategy and a dynamic search mode switching mechanism based on a grey wolf level are introduced, and an SBA-GWO algorithm is adopted for parameter optimization: in the first layer, SMO counter electromotive force THD is taken as fitness, and optimal gain is searched; in the second layer, the EKF estimation error quadratic sum is used as the fitness, and the Q / R adaptive residual noise time-varying property is optimized. And constructing an SMO-EKF cooperative control closed loop according to the optimized parameters to realize brushless direct current motor position-free control. Compared with the prior art, in the BLDC full-rotating-speed-domain position-free control, the dynamic response speed and the steady-state buffeting suppression effect are both considered, the robustness and the engineering realizability are remarkably improved, a physical sensor is not needed, and the engineering cost is low.

The invention provides a power supply mode switching method and device, a vehicle and a storage medium, and relates to the field of high-voltage power supply. And when the motor supplies power to the whole vehicle and the power supply for supplying power to the whole vehicle needs to be converted from the motor to the high-voltage battery, the motor is controlled to stop generating power. Therefore, when the motor and the high-voltage battery are a high-voltage power supply, the high-voltage battery is regarded as a load, and the battery relay of the high-voltage battery is closed, the battery relay is prevented from being damaged. After the motor stops generating power, the motor is in a driving mode, the motor cuts a stator winding due to residual magnetism and generates back electromotive force with residual inductance, and when the back electromotive force is large, the motor enters a three-phase parallel common-path active discharge mode, so that the current of the three-phase winding is multiplied. And when the current of the three-phase winding is multiplied, the back electromotive force is rapidly reduced, and the rapid discharge of the back electromotive force can be realized. After the motor enters the active discharge mode, the counter electromotive force is detected, so that the battery relay of the high-voltage battery is closed when the counter electromotive force is small, and the error switching risk when the active discharge mode does not reach the expectation is avoided.

The invention discloses a motor permanent magnet health state online evaluation and residual life prediction method and system, and belongs to the technical field of motor state monitoring and fault prediction. The method comprises the following steps: state monitoring and signal acquisition working condition judgment; a back electromotive force signal and a d-axis injection optimization high-frequency signal are collected; performing FFT analysis, calculating THD, and identifying d-axis inductance Ld on line; fTHD and delta Ld are calculated; carrying out normalization on the characteristic quantity FTHD and the delta Ld, and carrying out cross validation; under the balance of the three-phase voltage, the health index HImagnet of the permanent magnet is calculated; and fitting the descending trend of the HImagnet, and predicting the remaining useful life RUL. According to the method, the evaluation precision and robustness can be remarkably improved by fusing the two strongly correlated and complementary characteristic quantities of the back electromotive force harmonic distortion FTHD and the d-axis inductance variation delta Ld, real-time early warning of the demagnetization fault of the permanent magnet is realized, and trend prediction of the residual life is realized.

The invention discloses a brushless motor rotor angle determination method and device, equipment and a storage medium. The method comprises the following steps: synchronously acquiring original angle data of a Hall sensor, an incremental encoder and a back electromotive force observation module; respectively determining confidence coefficients of the Hall sensor, the incremental encoder and the back electromotive force observation module according to the rotating speed of the rotor, and performing weighted fusion on the original angle data of the Hall sensor, the incremental encoder and the back electromotive force observation module to obtain an initial fusion angle; based on the motor temperature, the motor phase current and the rotor speed, calculating a temperature drift compensation angle through a segmented temperature drift coupling model, and compensating the initial fusion angle according to the temperature drift compensation angle to obtain a temperature drift compensated angle; and inputting the temperature drift compensated angle into an extended Kalman filter for state estimation and filtering to obtain a rotor angle estimation value at the current moment. By means of the method, high-precision real-time calculation of the rotor angle within the wide temperature range and the full rotating speed range can be achieved.

One aspect of the present disclosure provides an electric work machine including a brushless motor, a drive circuit, and a control circuit. The control circuit executes a driving operation, a braking operation, and a switching operation. In the driving operation, the brushless motor is rotated based on a back-EMF of the brushless motor. In the braking operation, a switch pair of six switches in the drive circuit is turned on, and the other four switches are turned off. The switching operation is performed during the braking operation. The switching operation includes switching the switch pair. In the switching operation, an off-target switch is turned off based on an electric current flowing through the off-target switch satisfying an off-requirement.