225 results about "Stator voltage" patented technology

The invention relates to the technical field of inverter power control, and discloses a given current-based inverter power control method and system, and the method comprises the steps: calculating a fluctuation compensation parameter based on a bus voltage, and carrying out the real-time compensation of a q-axis basic current, and obtaining a first given q-axis current; predicting the bus voltage of the next period and correcting the first given q-axis current in advance to obtain a second given q-axis current; on the basis of the stator voltage saturation state, weak magnetic d-axis current given is generated, low-pass filtering is carried out on the second q-axis current given and the weak magnetic d-axis current given, and a d-axis current instruction and a q-axis current instruction are obtained; a PWM driving signal corresponding to a dq-axis current instruction is generated, an inverter switch is controlled, meanwhile, a power deviation signal is collected to update q-axis basic current, accurate prediction of bus voltage and advanced correction of given current are achieved, compared with traditional lag compensation, the dynamic response is faster, and the power control precision and the operation stability are improved.

The invention discloses an AC excitation system rotor initial position on-line identification method and system, and the method comprises the steps: collecting a stator three-phase voltage signal when a stator is no-load, carrying out the Clarke conversion of the signal, obtaining a voltage component under a static coordinate system, and carrying out the low-pass filtering processing; calculating a stator flux linkage based on the stator current and the processed voltage component, and calculating a rotor flux linkage based on the rotor current; the rotor initial position offset is continuously accumulated through closed-loop adjustment by calculating the stator and rotor flux linkage angle and the phase difference until the phase difference approaches zero, and the accumulated rotor initial position offset is output; and combining the mechanical angle output by the encoder with the accumulated rotor initial position offset to obtain a corrected rotor position angle, and updating the corrected rotor position angle to an excitation system. According to the method, the in-phase characteristics of stator and rotor flux linkages are utilized, and the optimally designed low-pass filter is combined, so that the identification precision of the initial position of the rotor is remarkably improved, and the zero offset of the encoder is effectively compensated.

The invention relates to the technical field of power systems, in particular to a parameter prediction and control method and system of a sensorless motor. The method comprises the following steps: acquiring a sampling stator current and a sampling stator voltage of a motor and a motor rotating speed observation value obtained through an orthogonal phase-locked loop, and performing coordinate transformation on the sampling stator current to obtain a two-phase static coordinate system current; inputting the sampled stator voltage, the two-phase static coordinate system current and the motor rotating speed observation value into a sliding mode observer to obtain a back electromotive force observation value; inputting the back electromotive force observation value into a pre-constructed cross feedback frequency adaptive filter, eliminating harmonic waves and extracting a fundamental component to obtain a filtered fundamental wave back electromotive force observation value; and normalizing the fundamental wave back electromotive force observation value, and inputting the normalized fundamental wave back electromotive force observation value into an orthogonal phase-locked loop to obtain a motor rotor position prediction value and a rotating speed prediction value. By adopting the cross feedback frequency adaptive filter, the quality of the back electromotive force signal is improved, and the accuracy of rotor position and speed estimation is also 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.

An electric drive system includes an electric machine having a stator assembly and a rotor assembly. The stator assembly has a plurality of multi-phase stator windings, including a first stator winding and a second stator winding. A first inverter is adapted to feed the first stator winding. A second inverter is adapted to feed the second stator winding. The rotor assembly includes rotor windings having a single phase. A controller is configured to selectively command excitation of the rotor windings with a pulsed field current such that a direct-axis (d-axis) stator flux linkage is generated. A d-axis stator voltage is induced in the first stator winding and the second stator winding by the d-axis stator flux linkage. Pulsed power transfer is enabled through interaction of the d-axis stator voltage and respective d-axis winding currents in the first stator winding and the second stator winding.

A method for Field Oriented Control (FOC) of a Permanent Magnet Synchronous Motor (PMSM) with a constant Power Factor Control (PFC) Loop includes measuring a rotor position of the PMSM. A plurality of stator voltages of the PMSM is controlled with a required direct (d)-axis current, a required quadrature (q)-axis current, the rotor position and a plurality of measured stator currents of the PMSM in a three-phase stationary reference frame. The required d-axis current is determined with a required power factor, the plurality of measured stator currents transformed into two-phase stationary reference frame, the measured stator currents transformed into a rotational reference frame, and each of a required α-axis voltage and a required β-axis voltage transformed into the two-phase stationary reference frame, wherein a power factor of the PMSM is controlled to be equal to the required power factor.

The invention discloses a model-free sliding mode single-loop control method for a permanent magnet synchronous motor. The method comprises the following steps: step 1, establishing a permanent magnet synchronous motor mathematical model under a d-q coordinate system; step 2, establishing a hyperlocal model of the permanent magnet synchronous motor; step 3, designing a system state equation, including establishing equations of state variables and matching disturbance, non-matching disturbance and q-axis stator voltage; 4, designing a finite time generalized proportional-integral observer for estimating matching disturbance and non-matching disturbance and estimating the change rate of the non-matching disturbance; and step 5, designing a single-loop model-free sliding mode speed controller to obtain the single-loop model-free sliding mode speed controller. According to the model-free sliding mode single-loop control method for the permanent magnet synchronous motor, the permanent magnet synchronous motor hyper-local model is established, the designed permanent magnet synchronous motor hyper-local model does not contain any motor parameter, the dependence on the motor parameter of the system is eliminated, and the anti-interference capability of the system is improved.

The invention provides a method for enhancing transient stability of a grid-forming type doubly-fed fan. The method comprises the following steps: acquiring a current actual power grid voltage and a current actual stator voltage; determining a first theoretical curve based on the current actual power grid voltage; determining a current theoretical stator voltage corresponding to the current actual power grid voltage based on the current actual power grid voltage and the first theoretical curve; determining a given stator voltage based on the current theoretical stator voltage and the current actual stator voltage; determining an active power reference value based on the current theoretical stator voltage; and determining a compensation phase angle based on the current theoretical stator voltage and the current actual power grid voltage. Through the ways of dynamically adjusting the stator voltage and the active power reference value, directly compensating the phase angle and the like, power angle stability, fault current suppression and reactive support can be comprehensively considered, and the safe and stable operation capability of the grid-forming type double-fed fan under the working conditions of power grid voltage amplitude drop and phase jump is effectively improved.

The invention provides a damping boosting method for a high-inertia energy storage type synchronous phase modifier based on stator voltage feed-forward compensation, which is used for respectively calculating d-axis compensation modulation voltage and q-axis compensation modulation voltage of a grid-side converter and a rotor-side converter, and is used for enhancing small-disturbance stability in an HIESSC wide-slip operation range. Under a weak power grid connection condition, the method feeds HIESSC stator voltage disturbance forward to a rotor side converter and a grid side converter controller output voltage through a transfer function, so that reduction of a negative resistance region of HIESSC impedance characteristics can be realized, and adverse effects of grid-connected point voltage disturbance are inhibited, thereby improving the HIESSC impedance characteristics and enhancing small disturbance stability of an HIESSC grid-connected system.

The invention discloses a transient reactive characteristic modeling method for a flexible excitation system under a power grid voltage fault, and the structure and a control block diagram of the system meet the following requirements: a synchronous generator is connected with a three-phase voltage source type converter, the three-phase voltage source type converter is connected with a chopping converter, the chopping converter outputs excitation voltage according to a system control signal, and the excitation voltage is converted into the excitation voltage. Therefore, excitation current is provided for the synchronous machine. The modeling process comprises the following steps: analyzing a synchronous machine equivalent diagram and an AVR control block diagram in the flexible excitation system so as to establish a corresponding mathematical model; then voltage and current parameters of a synchronous machine end of the system in a steady state before a fault are calculated; the transient current caused by the stator voltage change and the excitation voltage change is further solved respectively; and finally, the transient reactive power of the synchronous machine side of the flexible excitation system is obtained. The method provides a theoretical basis for realizing dynamic strong excitation control of the flexible excitation system and improving the stability of the system under a transient condition.

The invention discloses a position-sensorless control method for double three-phase synchronous reluctance motors, and relates to the technical field of motor control. Establishing a motor mathematical model, and performing vector space decoupling transformation to obtain a voltage and flux linkage equation; deriving from a stator voltage equation to obtain a current and voltage model; the current model and the voltage model are combined to obtain a mixed type effective flux linkage observer; obtaining a result of dq-axis self-inductance and mutual inductance changing along with dq-axis current through finite element simulation; a mutual inductance value is introduced, dq-axis self-inductance and mutual inductance values are updated in real time through a table look-up method, position errors caused by magnetic saturation and a cross coupling effect are compensated, and an optimized mixed type effective flux linkage observer is obtained; and sending the observation result as an input signal to a phase-locked loop, and outputting the position and speed information of the motor. According to the hybrid flux linkage observer based on a current model and a voltage model, inductance nonlinear change caused by magnetic saturation and cross coupling effects is compensated on the basis, and the observation precision of the position observer is improved.

The invention discloses a non-electrolytic capacitor permanent magnet motor control method and system based on a non-linear observer, and the method comprises the steps: introducing a gradient search mechanism based on a stator voltage equation of a permanent magnet synchronous motor under a static coordinate system, and constructing a flux linkage observer equation; acquiring a voltage component and a current component of the permanent magnet synchronous motor in a static coordinate system, and observing the flux linkage observer equation to obtain a real component of a flux linkage amplitude error in a rotating coordinate system; and designing an exponential reaching law adaptive law, introducing an exponential reaching law to dynamically adjust the gradient search gain, and combining the real component of the flux linkage amplitude error under the rotating coordinate system as feedback to obtain the rotor position of the permanent magnet synchronous motor. The estimated flux linkage error value is used as the feedback quantity, and the real position of the rotor of the permanent magnet synchronous motor can be quickly and accurately tracked. The non-electrolytic capacitor permanent magnet motor control method and system based on the non-linear observer can be widely applied to the technical field of permanent magnet motor control.

The invention relates to a sensorless brushless direct current motor direct torque control method based on robust extended Kalman filtering. The method comprises the following steps: acquiring stator voltage and current, and estimating an estimated rotor position, an estimated speed and an estimated electromagnetic torque of a motor through a robust extended Kalman filtering algorithm; determining a voltage space sector where a rotor flux linkage vector is located based on the estimated rotor position and the estimated speed of the motor; determining a target value based on the estimated electromagnetic torque and a reference electromagnetic torque, the target value being used to characterize a magnitude of desired electromagnetic torque adjustment; based on the voltage space sector where the rotor flux linkage vector is located and the target value, a voltage vector corresponding to the motor is obtained, and the voltage vector is used for driving the rotor flux linkage vector to rotate in the needed direction. By adopting the method, accurate control of the motor is realized without adopting a sensor.

The invention relates to a dual three-phase permanent magnet synchronous motor turn-to-turn short circuit fault adaptive diagnosis method, and belongs to the technical field of motor fault diagnosis. A mathematical model and an adjustable model of a dual three-phase motor turn-to-turn short circuit fault are established, space vector decoupling transformation of a multi-phase motor is combined, a short circuit fault component is introduced into a harmonic sub-plane of a stator voltage equation, and a fault characteristic value is designed by using an x-y current residual error of a real motor and the adjustable model. A fundamental wave amplitude is extracted through orthogonal Fourier transform to serve as a fault degree feature, a model reference adaptive law of an observer and a segmented PI regulator based on a mapping relation between a short-circuit current residual error and a fault turn ratio is constructed, PI parameters are dynamically adjusted according to the rotating speed and the load working condition, and adaptive feedback estimation of the short-circuit turn ratio is achieved. The fault feature extraction precision and real-time performance are improved, the fault-tolerant algorithm is simplified, the parameter design of the disturbance observer is optimized, the problem of diagnosis distortion caused by working condition changes is solved, and a motor monitoring optimization solution is provided.

The invention discloses a permanent magnet synchronous motor control method and system based on online parameter identification, and relates to the field of motor control, and the control method comprises the steps: building a motor mathematical model of a permanent magnet synchronous motor in a static coordinate system, and the mathematical model is used for describing the relation between stator voltage and current and rotor electrical angle and electrical angular velocity; constructing a flux linkage observer, estimating a rotor flux linkage by observing the stator voltage and current, and calculating the position and speed of the rotor based on the rotor flux linkage; a recursive least square method is adopted to carry out online parameter identification, and motor parameters are updated in real time to compensate the influence of parameter changes on the control precision. According to the position-sensorless control method provided by the invention, accurate rotor position and speed estimation can be realized, and efficient control is realized. In combination with a gain adjustment and compensation method, the system can automatically adjust a control strategy according to different working conditions during motor operation, and the stability, precision and robustness of the system are improved.

The invention discloses an enhanced hybrid synchronous control method for a grid-forming doubly-fed wind power converter, and belongs to the field of electrical engineering. The control method comprises enhanced hybrid synchronous control based on a self-adaptive integrator, reactive-voltage droop control and stator voltage and rotor current double-closed-loop control. In order to solve the problem that the resynchronization stability problem of the grid-forming type doubly-fed wind power converter cannot be solved when a traditional grid-forming type converter depends on a hybrid synchronization control algorithm of virtual impedance and is faced with fault scenes such as power grid voltage drop and the like, an existing parameter design method is not suitable for a grid-forming type doubly-fed wind power converter system any more. According to the invention, the voltage synchronization loop based on the adaptive integrator is introduced, so that existence of a stable working point during a fault period is powerfully ensured. And the built adaptive integrator parameter design principle can ensure the synchronous and stable adaptive adjustment capability of the doubly-fed wind power converter under different fault working conditions.

The invention discloses an AC excitation system no-load voltage buildup and pre-synchronization grid-connected control method and system, and the method comprises the steps: obtaining the amplitude and phase of a power grid voltage in real time through a phase-locked loop when the rotating speed of a doubly-fed induction motor reaches a synchronous rotating speed range; detecting the mechanical position of the rotor by using an encoder and calculating a slip angle; carrying out fundamental component extraction and phase correction on the stator side no-load voltage; setting a stator voltage target value based on power grid voltage directional control and calculating target rotor current; constructing a rotor current inner loop control loop, calculating a feedforward decoupling item and performing phase compensation; superposing a stator voltage outer loop control loop, and correcting the rotor current through closed-loop adjustment to eliminate the deviation between the stator side no-load voltage and the power grid voltage; and when a preset synchronization condition is satisfied, closing the grid-connected circuit breaker and switching a control mode. Accurate no-load voltage buildup and smooth pre-synchronization grid connection of the excitation system are achieved through a double closed-loop control structure, and the stability and reliability of the grid connection process are improved.

The invention relates to the technical field of motor control, and particularly provides a permanent magnet synchronous motor sensorless control method and system, and the method comprises the steps: designing a linear state observer according to a stator voltage equation of a permanent magnet synchronous motor, and replacing an error linear term in the linear state observer with a nonlinear function containing an error term, a generalized nonlinear state observer is formed to accurately obtain the back electromotive force estimation value of the motor, a traditional orthogonal phase-locked loop is improved, a parallel phase-locked loop structure is adopted, the back electromotive force estimation values of a # imgabs0 # shaft and a # imgabs1 # shaft are subjected to parallel calculation, and rotor position estimation and rotor speed estimation are obtained. The generalized nonlinear state observer and the parallel-connected phase-locked loop structure are designed to replace a traditional second-order linear state observer and a cascaded orthogonal phase-locked loop structure, and the dynamic performance, the anti-interference performance and the rotor position estimation precision of the permanent magnet synchronous motor under complex working conditions are effectively improved.

The present invention discloses a method for adaptive reactive power limit support for doubly-fed wind turbines based on voltage drop depth, comprising: Step 1: Upon detecting a system short-circuit fault, obtaining the stator voltage drop depth; Step 2: Detecting the wind turbine's operating status after the fault and determining a reactive current proportionality coefficient using wind turbine parameters; Step 3: Determining a reactive power setpoint based on the reactive current proportionality coefficient and the voltage drop depth. This invention proposes an adaptive reactive power support control method that replaces the fixed control coefficients used in grid-connection standards. This method enables doubly-fed units to provide maximum reactive power support based on operating conditions, tapping the wind turbine's reactive power potential and thus broadening the range of fault ride-through capabilities.

The invention discloses a permanent magnet synchronous motor gradient three-parameter identification dead-beat current prediction method, which comprises the steps of reconstructing a motor stator voltage and current equation based on an initial motor parameter estimation value in a controller; injecting a periodic high-frequency excitation signal on the d-axis current reference value to construct a continuous excitation condition required by parameter identification; establishing a parameter identification model based on inductance, resistance and flux linkage based on the current prediction error of the d axis and the q axis, and updating a parameter estimation value in the controller by adopting a gradient descent method according to the model; a convergence step size value range is determined based on Lyapunov stability analysis, and global convergence and system stability in a gradient iteration process are ensured. According to the method, the problem of motor parameter disturbance is effectively solved, and the stability, dynamic responsiveness and robustness of a motor control system are remarkably improved under the condition that other complex hardware is not added.

The application discloses a network-constructing double-fed wind turbine grid connection method and device, equipment, storage medium and product, relates to the network-constructing double-fed wind turbine grid connection control technical field, and includes: in the case that the rotational speed of the network-constructing double-fed wind turbine is constant and the voltage of the direct current side capacitor is constant, the stator voltage phase and the stator voltage amplitude of the network-constructing double-fed wind turbine are adjusted to be synchronized with the power grid; the real-time voltage difference between the power grid voltage and the stator end voltage of the network-constructing double-fed wind turbine is detected; in the case that the real-time voltage difference is less than a preset threshold value, the grid connection breaker is controlled to close, and the network-constructing double-fed wind turbine is smoothly and stably connected to the power grid; wherein the grid connection breaker is arranged between the network-constructing double-fed wind turbine and the power grid. The application can realize the smooth and stable grid connection of the network-constructing double-fed wind turbine.

An electric drive system includes an electric machine having a stator assembly and a rotor assembly. The stator assembly has a plurality of multi-phase stator windings including a first stator winding and a second stator winding. A first inverter is configured to power the first stator winding. A second inverter is configured to power the second stator winding. The rotor assembly includes single-phase rotor windings. A controller is configured to selectively command excitation of the rotor windings with a pulsed field current such that stator flux linkage is created in the direct axis (d-axis). A d-axis stator voltage is induced in the first stator winding and the second stator winding by the stator flux linkage in the d-axis.The interaction of the d-axis stator voltage and the corresponding d-axis winding currents in the first stator winding and the second stator winding enables pulsed power transmission.

The application provides a method for observing rotor flux of an alternating current motor, and belongs to the technical field of motor control. The method comprises the following steps: calculating rotor observation flux based on a first voltage-type flux calculation model and stator voltage and stator current in a two-phase static coordinate system; obtaining an amplitude deviation by subtracting the amplitude of the rotor rated flux from the amplitude of the rotor observation flux, and obtaining a deviation compensation quantity by multiplying the amplitude deviation by a proportional integral operation; and compensating and correcting the first voltage-type flux calculation model based on the deviation compensation quantity to obtain a voltage-type flux calculation model with compensation correction, so that the amplitude of the rotor observation flux converges. The application converges the rotor observation flux to the rotor given flux by connecting a correction link based on the traditional voltage-type flux calculation model, and finally realizes accurate flux position observation.

The present invention proposes a position sensorless predictive control method and system for a permanent magnet synchronous motor, relating to the field of motor control technology. The method comprises calculating the d- and q-axis voltages and d- and q-axis currents of the motor; using the q-axis stator current observation value, the motor speed observation value, and the load torque observation value as state variables, and the q-axis stator current error as feedback, to determine the observed value of the motor speed; calculating the motor stator current based on the observed value of the motor speed; using the total unknown part of the motor system and the motor stator current as state variables, and the current observation error as feedback, to determine the αβ-axis stator current values ​​of the motor; and obtaining the desired stator voltage value based on the αβ-axis stator current values ​​of the motor, thereby controlling the motor using the desired stator voltage value. The present invention can effectively improve the observation accuracy and the anti-disturbance capability of the control system, and combines position sensorless control with predictive control to effectively improve the dynamic characteristics of the control system.

The invention discloses a rotating speed estimation method, system and device for a permanent magnet synchronous motor without a position sensor, and the method comprises the steps: obtaining the d-axis stator current and d-axis stator voltage of the motor in a current control period; reconstructing the d-axis stator current and the d-axis stator voltage of the current control period based on the rotor flux linkage and the d-axis inductance of the motor to obtain a d-axis expansion current and a d-axis expansion voltage; and inputting the d-axis expansion current and the d-axis expansion voltage of the current control period into an adaptive observer to obtain a rotating speed estimation value and a rotor position estimation value of the motor in the current control period. According to the rotating speed estimation method, the rotating speed and the rotor position of the salient pole permanent magnet synchronous motor can be estimated through the adaptive observer, the rotating speed and the rotor position of the non-salient pole permanent magnet synchronous motor can also be estimated, and meanwhile the rotating speed and rotor position estimation precision of the motor is guaranteed.

The invention discloses a permanent magnet synchronous motor control method, system and device based on H infinity filter, a medium and a product, and relates to the field of motors, and the method comprises the steps: optimizing the parameters of a permanent magnet synchronous motor at the current moment based on the H infinity filter; the permanent magnet synchronous motor parameters comprise stator resistance, stator inductance and permanent magnet flux linkage of the permanent magnet synchronous motor; based on the output rotating speed and the reference rotating speed of the permanent magnet synchronous motor at the current moment, a PI controller is adopted to determine reference stator current; based on the reference stator current, weak magnetic control is adopted to generate a stator current component; based on the stator current component and the optimized parameters of the permanent magnet synchronous motor, a mathematical model of the permanent magnet synchronous motor is adopted to calculate a reference stator voltage component; and converting the reference stator voltage component into a switching pulse of an inverter through space vector pulse width modulation so as to drive the permanent magnet synchronous motor. According to the invention, the control precision and robustness of the permanent magnet synchronous motor can be improved.

This invention discloses a method and system for no-load voltage build-up and pre-synchronization grid connection control of an AC excitation system. The method includes: acquiring the amplitude and phase of the grid voltage in real time via a phase-locked loop when the speed of the doubly-fed induction motor reaches the synchronous speed range; detecting the rotor mechanical position and calculating the slip angle using an encoder; extracting the fundamental component and correcting the phase of the stator-side no-load voltage; setting a target value for the stator voltage based on grid voltage-oriented control and calculating the target rotor current; constructing an inner-loop control loop for the rotor current, calculating the feedforward decoupling term and performing phase compensation; superimposing an outer-loop control loop for the stator voltage, and correcting the rotor current through closed-loop adjustment to eliminate the deviation between the stator-side no-load voltage and the grid voltage; and closing the grid connection circuit breaker and switching the control mode when the preset synchronization conditions are met. The dual-closed-loop control structure achieves precise no-load voltage build-up and smooth pre-synchronization grid connection of the excitation system, improving the stability and reliability of the grid connection process.

The present invention discloses a control method, device, motor, storage medium and processor for a motor. The method includes: in the field weakening control system of the motor, a single q-axis current regulator is adopted to freely switch between field weakening traction and braking control under field weakening conditions; in the control system of the single q-axis current regulator, a field weakening compensation module is added to perform field weakening compensation processing on the d-axis and q-axis currents of the motor; and an out-of-control limiting and compensation module is added to perform out-of-control limiting and compensation processing on the field weakening current of the motor to obtain the voltage vector angle of the field weakening control system of the motor; according to the voltage vector angle and the maximum stator voltage of the motor, the dq-axis reference voltage vector of the motor is determined to drive and control the system where the motor is located. With this solution, by adopting a single current loop control structure in the field weakening control of a permanent magnet synchronous motor and using a limiting method and a current compensation method for field weakening control, the stability of the control system of the permanent magnet synchronous motor can be improved.

A control device includes a current detector that detects a stator current flowing between a voltage application unit and a stator winding of a rotating machine; a control unit that computes a voltage command value that is a command value for a stator voltage to be applied to the stator winding on the basis of the stator current and a rotor position serving as position information of a rotor of the rotating machine; a PWM modulator that performs on-off control of switching elements of the voltage application unit so that a smoothed value of the stator voltage matches the voltage command value; and a position estimator that estimates, on the basis of the voltage command value and the stator current, the rotor position through a filter that removes a frequency component of a fundamental frequency of rotational speed of the rotating machine.

A method for providing grid formation control of a doubly-fed generator of a wind turbine includes receiving one or more voltage commands from an external controller via a stator voltage regulator of a converter controller. Further, the method includes determining one or more rotor current commands from a magnetizing current command and a stator current feedback signal of the doubly-fed generator via the stator voltage regulator. Accordingly, the method includes using the one or more rotor current commands to control a rotor voltage of the doubly-fed generator to achieve the one or more voltage commands.