1091 results about "Voltage vector" patented technology

The invention discloses a decoupling control method and system for a matrix motor with harmonic suppression capability, and belongs to the technical field of motor driving systems, and the method comprises the steps: building a matrix motor current loop mathematical model which considers a DC disturbance term and an AC disturbance term at the same time; based on the matrix motor current loop mathematical model, establishing a self-adaptive quasi-resonance extended state observer which simultaneously considers direct current disturbance observation and alternating current disturbance observation and performs self-adaptive adjustment on control parameters; the direct current and alternating current lumped disturbance of a matrix motor current loop is observed in real time through an adaptive quasi-resonance extended state observer; compensating the observed direct current and alternating current lumped disturbance in a forward controller of the current loop and obtaining a voltage control quantity; and controlling the matrix motor through a voltage vector space transformation and SVPWM modulation method according to the voltage control quantity. The method is improved and optimized based on an existing matrix motor vector control system, and the system does not need to be modified on a large scale.

The invention discloses a dual three-phase permanent magnet motor current control method and system under high speed and low carrier wave ratio, and belongs to the technical field of permanent magnet motor control. The method mainly comprises the following steps: reconstructing a motor mathematical model by adopting VSD conversion and Park conversion; designing a linear expansion state observer; a reference value of an output voltage vector is obtained in combination with deadbeat predictive current control; and performing time delay compensation and angle delay compensation on the output voltage vector to obtain a reference value of a final output voltage vector, sending the reference value to an SVPWM module for modulation, and outputting a PWM pulse signal for driving a motor. No motor parameter is used in the current loop design process, system errors caused by mismatching of the motor parameters can be avoided, and the system robustness is improved; meanwhile, only one control parameter needs to be determined, the parameter setting difficulty is greatly reduced, and stable operation of the high-speed permanent magnet motor under the low carrier wave ratio is achieved.

The invention discloses a control method of a power converter based on subspace predictive control, which is used in the technical field of power converter control, and comprises the following steps: constructing a subspace predictor model of the power converter based on a historical data matrix of the power converter; predicting a linear part of the model and predicting a nonlinear part through a neural network; based on the linear part predicted value and the non-linear part predicted value of the current control period, obtaining a function relational expression of a future predicted output current; determining the optimal input voltage of the current control period based on the target function; and constructing a cost function by using the optimal input voltage of the current control period and the voltage vectors corresponding to the switching states of the power converter, and taking the switching state corresponding to the voltage vector when the value of the cost function is minimum as the optimal switching state of the current control period. The state of the power converter can be accurately predicted, and the negative influence of parameter mismatch on the power converter is reduced.

The invention discloses a high-precision model predictive current control method suitable for a dual three-phase permanent magnet synchronous motor, which comprises the following steps of: deducing a current discrete model of the dual three-phase permanent magnet synchronous motor by considering the change of a rotor position in a control period; constructing a candidate virtual voltage vector set consisting of 24 virtual voltage vectors and zero vectors, wherein the voltage components of the 24 virtual voltage vectors are 0 on a voltage vector xy plane; taking the error squares of the dq-axis current and the xy-axis current of the dual three-phase permanent magnet synchronous motor at the end of each control cycle as evaluation indexes, constructing a cost function, and evaluating the errors of the dq-axis current and the xy-axis current corresponding to different voltage vectors in the candidate virtual voltage vector set at the end of each control cycle by using the cost function. And screening to obtain a voltage vector with the minimum cost function and outputting the voltage vector. The method has smaller dq-axis current tracking error and electromagnetic torque tracking error when the motor operates at a low carrier wave ratio, and improves the steady-state performance of motor operation.

The invention relates to the technical field of inverter pulse width modulation, in particular to a neutral-point potential balance and low common-mode voltage modulation method and system based on an SVPWM inverter, and the method comprises the steps: determining a basic voltage vector based on different switching states of an NPC three-level inverter; respectively determining the midpoint current of each fundamental voltage vector, and determining the fundamental voltage vector causing midpoint potential deviation; combining with a large vector and a zero vector, and performing mode division of a single vector space region; determining an expected current according to the DC side capacitor voltage of the inverter, and constructing a target function based on the expected current; and performing region judgment according to the output synthesized voltage vector, determining a corresponding optimal division mode, obtaining each basic voltage vector of the synthesized voltage vector and a corresponding duty ratio, and determining a switching sequence to obtain a PWM wave. While the neutral-point potential balance and common-mode voltage suppression of the NPC three-level inverter are realized, the switching frequency of the inverter is effectively reduced, and the switching loss is reduced.

The invention relates to a permanent magnet synchronous motor current control method of an adjustable switching frequency FCS-MPC. Compared with the prior art, the defect that the switching frequency of an inverter is not fixed in current control of an existing FCS-MPC permanent magnet synchronous motor system is overcome. The method comprises the following steps: acquiring data of a driving system; constructing a discrete current prediction control model; determining a cost function and a delay compensation strategy; calculating a current error control band degree; selecting an optimal voltage vector; and outputting the voltage vector. According to the invention, the unique advantages of the FCS-MPC are reserved, and the defect that the inherent switching frequency is not fixed is overcome, so that the FCS-MPC can operate under the specified switching frequency in a wide speed regulation range; by introducing the PI type switching frequency controller, the zero-static-error tracking of the switching frequency reference value can be realized, and the control method realizes the effective regulation and control of the switching frequency on the basis of ensuring the current control performance of the permanent magnet motor.

The present invention provides a method for cooperatively suppressing a common-mode voltage and current harmonics of coupled three-level inverters, comprising: based on amplitude and phase angle of reference voltage vector, determining sector and region in which the reference voltage vector is located; selecting four basic voltage vectors with low common-mode voltage amplitudes to synthesize the reference voltage vector; writing volt-second balance equation based on selected basic voltage vectors, and calculating duty cycles thereof; and based on sector and region in which reference voltage vector is located, set value of voltage difference across capacitors on direct current side, and actual value of voltage difference across capacitors on direct current side, (1) updating duty cycles of basic voltage vectors, to realize separate control of capacitor voltage; and (2) designing and converting switching sequence into PWM drive signal of power switch, to control the coupled three-level inverter to operate.

The invention discloses a frequency conversion vector control method for a digital energy-saving pump station, which belongs to the technical field of vector control and comprises the following steps: constructing a coupling vector model, simulating the running states of a pump unit under different working conditions through a virtual test signal, and automatically correcting the coupling vector model; operating data of a pump set are collected in real time, an operating situation feature set is constructed, predictive vector control is carried out, an optimal voltage vector sequence is generated, and meanwhile load fluctuation of a pipe network is predicted; demand pre-judgment is carried out on the starting and stopping time and the action amplitude of the anti-backflow device, a bidirectional disturbance suppression mechanism is constructed, current vector parameters are pre-adjusted, and calculus correction is carried out based on deviation judgment; when multiple pumps operate in parallel, the instantaneous operation efficiency point of the pump set is calculated in real time, the efficiency change trend is predicted, a load distribution scheme is generated, the comprehensive energy efficiency is evaluated, energy efficiency self-optimization is carried out, the comprehensive energy efficiency of the system is improved, and control experience reuse is achieved.

The invention relates to the technical field of grid-connected inverter control, and discloses a grid-connected inverter model predictive control method based on a neutral-point potential fluctuation control factor, in the process of controlling a grid-connected inverter by using model predictive control, firstly, an SVPWM method and the model predictive control method are combined, the design of an objective function is simplified, and the model predictive control factor is optimized; the optimal switch sequence can be selected only by calculating the midpoint potential deviation; secondly, neutral-point potential balance control is realized in spatial modulation, a large sector is further divided into a plurality of small sectors, the position of the small sector where a reference voltage vector is located is determined, a switch sequence is selected from the determined small sectors for traversal, the traversal frequency is reduced, and the calculation efficiency is improved; and finally, designing a midpoint potential control factor, and greatly reducing the content of high-amplitude common-mode voltage on the premise of ensuring the balance of the midpoint potential. Moreover, the overall control structure is clear and easy to implement, and the dynamic performance and the steady-state tracking performance of the controller are both improved.

The invention provides a non-cascade permanent magnet synchronous motor model prediction speed current control system and method, and relates to the technical field of motor control, the system realizes the tracking of the rotating speed and the current in the same loop by introducing a model prediction speed current controller, only needs to set three influence factor parameters, and can realize the tracking of the rotating speed and the current. And the parameter setting workload of the traditional double-PID controller is obviously reduced. By adopting the saturation function type sliding mode load observer, the problem of high-frequency buffeting is effectively relieved, and the accuracy of load torque estimation is improved. The model prediction speed current controller is based on a discretized permanent magnet synchronous motor model, voltage vector output is optimized by constructing a cost function, rapid tracking of current and speed is achieved, and the dynamic performance of the system is improved. The objective of the invention is to solve the problems of limited bandwidth, complex parameter setting and insufficient dynamic performance in a conventional cascade control structure.

The invention relates to the technical field of parallel three-level converter control, and provides a parallel three-level converter model prediction control method and system, and the method comprises the steps: enabling a parallel three-level converter to be modeled as a series connection of an equivalent voltage source and an equivalent filter inductor according to the Thevenin theorem, enabling the parallel three-level converter to be equivalent to a five-level converter, and enabling the parallel three-level converter to be connected in parallel; a three-layer optimization control strategy is adopted; in the first layer, a candidate vector closest to a reference voltage vector is selected as an optimal five-level basic vector so as to track a parallel total output current; in the second layer, a redundant five-level voltage vector is selected to balance the neutral-point voltage; and in the third layer, selecting the candidate switching state which enables the circulating current suppression value function to be the minimum as the optimal redundant three-level switching state so as to suppress the circulating current. The method can effectively reduce output current harmonics under low switching frequency, and balance of neutral-point voltage and effective suppression of circulating current are realized to ensure safe and stable operation of a parallel converter system.

The invention discloses a modulation method and system for suppressing common-mode voltage and midpoint low-frequency oscillation of a three-level inverter, and the method comprises the steps: obtaining a reference voltage vector, and judging a sector where the reference voltage vector is located according to the division condition of a space sector; according to the space sector division condition and the position of the reference voltage vector, a synthetic virtual vector and a corresponding basic voltage vector are obtained, and the action sequence of the basic voltage vector is determined; based on the action sequence of the basic voltage vector, virtual vector action time is calculated according to volt-second balance, the virtual vector action time is distributed to the basic voltage vector action time, and a pulse width modulation signal is output to control the on-off of a power device of the inverter, so that the common-mode voltage of the three-level inverter is suppressed, and the three-level inverter is obtained. And safe and stable operation of the system is guaranteed.

The invention discloses a three-level ANPC converter model prediction control method and device based on Newton iteration method vector optimization, and belongs to the technical field of converter control, and the method comprises the steps: building a mathematical model of a three-level ANPC converter under a three-phase static coordinate system based on the Kirchhoff theorem; performing forward Euler discretization on the mathematical model of the three-level ANPC converter to obtain a current prediction equation model; establishing a cost function according to the control target; performing online search on the optimal voltage vector according to a cost function; voltage vector synthesis is carried out, voltage vectors selected when the optimal voltage vector falls in 36 different small sectors, a voltage vector action sequence and action time distribution are obtained through calculation, and then the action time of a pair of redundant positive and negative small vectors in the voltage vectors is adjusted to carry out neutral point potential balance control. According to the invention, rapid optimal voltage vector search and three-level ANPC converter output current and neutral point potential control are realized.

The application discloses a kind of water electrolysis hydrogen production rectifier transformer harmonic active inhibition optimization method, comprising the following steps: constructing rectifier circuit, rectifier circuit includes switch tube, the voltage vector and zero vector of switch tube output are combined, and combined output voltage vector is obtained;The harmonic amplitude is obtained by processing combined output voltage vector, Levy tangent flight strategy and confidence domain variation strategy are introduced in black-winged kite optimization algorithm to construct improved dynamic search algorithm, the total harmonic distortion is obtained by iterative calculation of harmonic amplitude by improved dynamic search algorithm, i.e. optimal switch tube combination, the switch tube of rectifier circuit is adjusted by optimal switch tube combination, and the total harmonic distortion of rectifier circuit is reduced.The optimal switch tube combination of rectifier circuit is iteratively calculated by improved dynamic search algorithm in the application, effectively reduces resource consumption, and processing speed is accelerated, and the efficiency and accuracy of electrolytic water hydrogen production rectifier are improved.

The invention provides a power distribution network fault section rapid calibration method based on a feeder terminal. According to the method, power distribution network line electrical quantity and distributed power supply output information are collected in real time through a feeder terminal and preprocessed, then fault transient signals are processed through complete set empirical mode decomposition of mean value self-adaptive noise, and intrinsic mode components are obtained to judge fault types. Thirdly, fault section preliminary positioning is carried out, and an approximate area is determined according to a positive sequence voltage vector for a symmetric short-circuit fault, a negative sequence voltage vector for an asymmetric short-circuit fault and a zero sequence current amplitude for a single-phase earth fault; then accurate calibration is carried out, a single-phase earth fault is judged through a filter and correlation coefficients, and short circuit and broken line faults are calibrated through a model or an intelligent algorithm in combination with line topology and electrical parameters. And finally, establishing a target function containing a penalty term, converting the target function into a Markov decision process, solving through an approximate dynamic programming algorithm, realizing rapid and accurate calibration of a fault section, and improving the power supply reliability of the power distribution network.

The invention relates to the technical field of motor control, discloses a direct current brushless motor control method and system based on current prediction, and aims to solve the problems of large torque ripple, low efficiency and poor stability caused by current loop lag in the prior art. The method comprises the following steps: acquiring a motor operation state signal in real time; determining a sector and an electrical angular velocity based on the rotor position and the rotational speed; inputting related parameters into the mixed current prediction model to obtain a three-phase current prediction value of the next period; a prediction error is calculated in combination with a current instruction, and an optimal voltage vector enabling a cost function to be minimum is solved through a model prediction control algorithm; and finally, a space vector pulse width modulation signal is generated to drive an inverter. According to the method, advanced control is realized by fusing a physical model and a data-driven prediction mechanism, the torque ripple is remarkably reduced, and the energy efficiency and robustness are improved.

The invention provides an acceptance test method and system for a substation station end. The method comprises the steps that current test data and voltage test data of a plurality of power monitoring lines marked at the station end of a substation are acquired, the current test data comprise current monitoring coefficients of the power monitoring lines, and the current monitoring coefficients are related to line average current values, current vector deviations and line monitoring current variances; the voltage test data comprises a voltage monitoring coefficient of each power monitoring line, and the voltage monitoring coefficient is related to a voltage vector deviation and a voltage average achievement deviation; and according to the current test data and the voltage test data, abnormity monitoring is carried out on each power monitoring line to obtain line abnormity classification data, then line abnormal points are positioned to obtain position data of the line abnormal points, and line abnormity early warning is issued. According to the method, the problem of low acceptance efficiency caused by difficulty in simultaneous fault positioning of a plurality of test abnormal positions in the prior art is solved.

The invention discloses a predictive control method and system for a network-building type inverter, and belongs to the technical field of power electronics, and the method comprises the steps: building an output voltage prediction model according to the output voltage data and historical control input signals of the network-building type inverter at the current moment; obtaining a current output voltage prediction value through the output voltage prediction model; obtaining a reference voltage vector of the inverter at the next moment according to a preset optimization criterion function and the current output voltage predicted value, and obtaining an optimal control input signal at the next moment; and according to the optimal control input signal at the next moment, regulating and controlling a switch element of the grid-forming inverter. Therefore, by implementing the method and the device, the problems that a traditional output voltage prediction model is easy to generate model mismatch for an actual inverter, and the reliability of a prediction result is greatly reduced when the data of the current sensor is changed due to the fact that a traditional grid-forming inverter model excessively depends on the data of the current sensor in the prior art can be solved.

The invention is suitable for the technical field of flexible power distribution of a power system, and discloses a modular multilevel converter multi-objective optimization method, system and device based on model predictive control and space vector modulation, and a medium. Obtaining an output current reference value and a circulating current reference value; obtaining a reference voltage vector based on the output voltage reference value, and screening out a plurality of groups of redundant voltage vector sequences through a space vector diagram; performing performance evaluation through rolling optimization by combining each redundant voltage vector sequence with a multi-target cost function to obtain an optimal voltage vector sequence; and on the basis of the optimal voltage vector sequence and the corresponding duty ratio, a switching signal for driving each sub-module switching device of the MMC is generated, and multi-target cooperative control is realized. The three targets of reference output current tracking, circulating current suppression and sub-module capacitor voltage balance are met, and the dynamic response capability, efficiency and reliability of MMC system operation are comprehensively improved.

The invention discloses motor control equipment and a motor control method for a sine wave filter. The motor control method comprises the following steps: compensating a current feedback vector output by a driver through a filter state compensator to obtain a motor current feedback signal; a motor current feedback signal and a given signal are synchronously input to a motor controller for operation, a motor stator voltage given vector is obtained and output to a filter state compensator for further processing, and a driver output given voltage vector is obtained and serves as a voltage signal to control the bus voltage of the sine filter. According to the method, only the direct-current bus voltage and the three-phase output current of the driver are collected, the problem of hardware compatibility does not exist, the motor is controlled to run along with the given signal through external filter state compensation, high current control response bandwidth can be achieved, resonance is avoided, and stable running of the motor is guaranteed.

The invention discloses a flux weakening method of a permanent magnet synchronous motor finite control set model prediction control system based on an expected fundamental wave voltage closed loop, and belongs to the technical field of permanent magnet synchronous motor speed regulation control. According to the method, the problems of voltage saturation and poor robustness of a finite control set model prediction control system in a weak magnetic region are solved. According to the method, one-step delay compensation is carried out on the stator current, the stator current predicted value predicted through delay compensation is substituted into the voltage vector model under current vector dead beat control, and the compensated voltage vector reference value can be calculated. And an expected fundamental wave voltage vector is calculated based on the compensated voltage vector reference value, and finally the expected fundamental wave voltage vector is used as feedback of closed-loop flux-weakening control, so that maximum voltage control can be realized, and voltage saturation of a flux-weakening area is avoided. The method provided by the invention has better current dynamic performance, faster acceleration time and better robustness. The method can be applied to field weakening control of the permanent magnet synchronous motor.

The invention belongs to the technical field of power electronics, and relates to a hybrid device common bridge arm three-level split output inverter modulation method and system, and the method comprises the steps: obtaining a mapping phase angle, a modulation degree and a region number according to a reference voltage vector generated by a three-phase original modulation wave; mapping the phase angle, the modulation degree and the switching period according to the size of the modulation degree to obtain two kinds of vector action time; generating two modulation waves according to the area number and the action time of the two vectors; generating a first pulse driving signal according to the area number, the first modulation wave and the forward and reverse carrier waves; generating a final carrier according to the area number and the forward and reverse carriers, and generating a second pulse driving signal according to the second modulated wave, the forward carrier, the forward carrier of the previous period and the final carrier; and selecting a driving signal from the two pulse driving signals according to the area number. The modulation degree can be maximized, driving pulses are respectively generated in different modulation degree ranges, the output current quality is high, and the total harmonic distortion rate is low.

The invention relates to the technical field of flexible power transmission of a power system, in particular to a coordinated optimization method and system of a distributed power flow controller and a medium, and the method comprises the steps: building a layered equivalent coupling model of the distributed power flow controller; taking minimization of the total loss of the flexible power transmission system as an optimization target, and performing global optimization on a parallel side output voltage vector and a series side injection voltage vector of the distributed power flow controller by using a layered equivalent coupling model to obtain an optimal coordinated optimization control strategy; obtaining a target control parameter in a target control mode according to the optimal coordination optimization control strategy; and according to the target control parameter and the real-time voltage and current data of the power transmission line, calculating a voltage compensation amount needing to be injected into the flexible power transmission system, and according to the voltage compensation amount, carrying out coordinated optimization control on the power flow of the power transmission line. According to the method, the parallel side and the series side of the distributed power flow controller are coordinated and optimized by establishing the layered equivalent coupling model, so that the voltage stability and power flow equilibrium distribution of the flexible power transmission system are effectively improved.

The invention discloses a permanent magnet motor model prediction control method and system based on a triangular discrete space, and the method proposes a voltage vector discretization strategy based on a regular triangle, generates as many as 6 * 4 < n-1 > virtual voltage vectors through n times of iterative segmentation, and carries out the current prediction at a next moment through the virtual voltage vectors. And finally, screening out an optimal voltage vector by taking the minimum cost function value as a target, and using the optimal voltage vector for motor control. Besides, on the basis of virtual voltage vectors constructed by relying on midpoints of a regular triangle, under the enlightenment of exploring a specific geometrical relationship between the virtual voltage vector constructed in each layer of iterative segmentation process and the optimal voltage vector, efficient optimal voltage vector search is realized, the number of voltage vectors for online evaluation is effectively reduced, and the efficiency of online evaluation is improved. Therefore, the calculation burden is greatly reduced. According to the technical scheme, accurate control over the permanent magnet motor can be ensured, current harmonics of the motor can be effectively reduced, and thrust fluctuation is reduced.

The invention discloses a two-degree-of-freedom prediction control method of an LCL filtering type three-phase grid-connected inverter system, and belongs to the field of power electronic converter control. A prediction control reference instruction is obtained by sampling parameters of inverter side current, capacitor voltage, network side current and power grid voltage at the moment k, and a continuous and discrete model of an LCL filtering type three-phase grid-connected inverter system is established; designing a control function based on a grid-side current reference tracking error and a gradient thereof, and establishing a prediction model; constructing a prediction cost function based on a control function, and obtaining a prediction control reference instruction by using a minimum value of the prediction cost function; and determining an optimal voltage vector and an action duty ratio according to the prediction control reference instruction, generating a control pulse signal according to a symmetrical five-section pulse mode, and acting on each switching tube in the inverter to realize prediction control of the LCL filtering type three-phase grid-connected inverter system. The method is simple in step, convenient to use, constant in switching frequency and good in stability.

The invention provides a phase delay error suppression method for a midpoint current sensor of a T-type three-level inverter, and the method comprises the steps: determining a sector and a sub-region where a target voltage vector is located according to the input target voltage vector, selecting a basic voltage vector for synthesis according to the sub-region where the target voltage vector is located, calculating the action time of the voltage vector, and calculating the phase delay error of the midpoint current sensor of the T-type three-level inverter. The switching time of the seven-segment switch is determined, so that a seven-segment PWM switching signal is generated; judging whether the target voltage vector is located in an unobservable area according to the action time of the basic voltage vector; if yes, maintaining the original seven-segment PWM switching signal to send waves; otherwise, adjusting the seven-segment PWM switching signal, and compensating the observable voltage vector which does not meet the minimum sampling time by shifting the PWM signal to obtain a plurality of stable current sampling windows; and phase delay error compensation of the reconstructed three-phase current is realized according to the relationship between the sampling currents. According to the method, the distortion of the reconstruction current is improved, so that the precision of the three-phase reconstruction current is effectively improved.

The invention discloses a new energy grid-connected three-level inverter midpoint potential balance modulation method and system, and the method comprises the steps: carrying out the sector judgment and reference voltage vector mapping of three-phase reference voltages va, vb and vc from a controller; calculating an optimal switching waveform and time parameters da1, db1 and dc1 thereof according to the mapped three-phase reference voltages va1, vb1 and vc1, the sampled midpoint potential deviation V1-V2 and the three-phase current iabc, and reflecting the time parameters da1, db1 and dc1 into time parameters da, db and dc of each phase waveform of an original voltage sector; and inputting the time parameters da, db and dc of each phase waveform of the original voltage sector into a modulator to generate a modulation signal so as to control the three-level inverter. The invention aims at suppressing the neutral-point potential fluctuation of the new energy grid-connected three-level inverter and reducing the current harmonic wave and the switching loss at the same time.

The invention discloses a harmonic suppression predictive control method and module for a three-phase grid-connected inverter system, and belongs to the field of power electronic control. The method comprises the following steps: firstly, establishing a continuous domain state space model of a three-phase grid-connected inverter system under a dq coordinate system, discretizing the state space model at a k moment, and obtaining a prediction model of a k + 1 sampling power grid current; enabling the power grid current prediction model to reach a power grid current reference value at a k + 1 sampling moment, and calculating a reference inverter voltage control reference value; calculating a voltage control reference value of the inverter integrated with harmonic suppression by combining the voltage control reference value of the reference inverter and the discretized quasi-resonance controller; determining an optimal voltage vector and action time of an inverter voltage control reference value capable of synthesizing the integrated harmonic suppression; and generating a control pulse signal and applying the control pulse signal to a switching tube of the three-phase grid-connected inverter to realize harmonic suppression prediction control of the three-phase grid-connected inverter system. The steps are simple, and the harmonic prediction and suppression control effect is good.

The invention discloses a double-fan air conditioner and a single-inverter and double-motor control method thereof. The control method comprises the steps that three-phase currents of a master motor and a slave motor which are the same in type and connected to the same inverter are collected, Park conversion is conducted to obtain d-axis components and q-axis components, and the observation angular frequency of the master motor is obtained through a position observer; calculating error angles of the master motor and the slave motor, controlling errors of the error angles through feedback, outputting a product of a motor speed difference reference value and the error angles, and obtaining a d-axis component compensation value idcomp through PI control; inputting a main motor angular frequency reference value in a speed control loop, outputting d-axis and q-axis component reference values of the current of the main motor, and compensating the d-axis component reference value of the current of the main motor with idcomp to obtain a final d-axis component reference value of the current of the main motor; and inputting the q-axis component reference value and the q-axis component reference value into a current control loop, generating a duty ratio signal of pulse width modulation, and controlling a master motor and a slave motor to rotate a voltage vector. According to the invention, through d-axis current injection compensation, system stability is realized.

The invention relates to the field of intelligent medical treatment, in particular to an electrical impedance imaging method and device based on mixed excitation and a program product. Comprising the steps that an initial current vector and an initial boundary voltage vector of mixed excitation are obtained, the mixed excitation comprises L kinds of excitation, and L is a natural number larger than 1; performing weighted fusion on the L excitation initial current vectors to obtain a mixed excitation current vector, and performing weighted fusion on the L excitation initial boundary voltages to obtain a mixed excitation voltage; performing electrical impedance imaging optimization function calculation based on the mixed excitation current vector and the mixed excitation voltage to obtain conductivity change; the optimization function is used for carrying out regularization calculation on regional potential distribution and conductivity variation based on the mixed excitation current vector and the mixed excitation voltage; an electrical impedance distribution image is generated based on the conductivity change. According to the invention, the resolution of EIT imaging is improved, and the method has good clinical value.