A variable frequency converter instantaneous stop and restart method based on flux linkage state reconstruction

Abstract

The application belongs to the technical field of motor driving and control, and particularly relates to a variable frequency device instantaneous stop and restart method based on magnetic chain state reconstruction, which comprises the following steps: locking the inverter pulse and latching the initial rotor magnetic chain space vector when the DC bus is under voltage; continuously collecting the stator freewheeling current after the pulse is locked, and determining the stator freewheeling current zero value time according to the current zero value tolerance; obtaining the rotor electric angular velocity during power-off, updating the rotor magnetic chain state according to the rotor magnetic chain state equation containing the stator current forced term before the zero value time, setting the stator current forced term to zero from the zero value time and continuing to update to the pulse recovery time; if the pulse recovery time has not reached the zero value condition, the stator current forced term is kept updating to the pulse recovery time. The reconstructed rotor magnetic chain space vector obtained at the pulse recovery time is written into the vector controller, and the pulse locking is released, so as to reduce the rotor magnetic chain state deviation during the instantaneous stop and restart.

Description

Technical Field

[0001] This invention relates to the field of electric motor drive and control technology. More specifically, this invention relates to a method for instantaneous stop and restart of a frequency converter based on flux linkage state reconstruction. Background Technology

[0002] When industrial frequency converters drive fans, pumps, conveying equipment, and other inertial loads, DC bus undervoltage may occur due to grid fluctuations, upstream power supply switching, or short-term voltage drops. To protect the inverter power devices, the controller typically blocks the inverter pulse when the real-time DC bus voltage drops to the undervoltage action threshold. If the power supply is restored within the allowable instantaneous stop time, the frequency converter can perform speed tracking start, allowing the asynchronous motor that is still rotating to re-enter controlled operation.

[0003] Existing frequency converters can restart asynchronous motors after a short-term stop by re-acquiring the motor's operating status, such as speed and magnetic field direction, enabling the still-rotating motor to return to controlled operation. For example, Chinese patent document CN114640291B discloses a speed-tracking start method for asynchronous motors after a short-term stop. This method applies a zero vector to the three-phase inverter sequentially after a short stop and collects the three-phase current of the motor. It calculates the motor speed and magnetic field orientation angle using information such as the current vector angle and pulse release duration, and then uses the obtained speed and magnetic field orientation angle to initiate vector control. This technology avoids the problem of having to wait for the motor to completely demagnetize before restarting. Its key technology lies in using the actively applied zero vector and the resulting current response to obtain the speed and magnetic field orientation information required for restarting.

[0004] Regarding the handling of residual flux linkage during gate blocking, Japanese Patent Publication No. JP4667741B2 discloses an induction motor control device. After the power conversion device stops supplying power, this technology continues to calculate the restart flux linkage command based on the flux linkage, rotor speed, and motor circuit constant at the time of gate blocking. Simultaneously, it continues to advance the reference phase angle used for vector control, and uses the flux linkage command calculated during gate blocking as the initial value for restoring flux linkage control when power is restored. The patent further describes that its residual flux linkage attenuation relationship is based on the primary side after gate blocking. shaft current and The method is derived under the condition that the shaft current is zero from the moment of gate blocking; in another embodiment, the primary side current is also assumed to be zero during gate blocking as a condition to simplify the estimation of residual flux. Thus, it can be seen that the prior art can continuously estimate the residual flux based on the existing flux state, speed, and motor parameters during gate blocking, and use the estimation results for vector control recovery.

[0005] The aforementioned prior art demonstrates that the restart process of an asynchronous motor after an instantaneous stop can be improved by acquiring speed and magnetic field orientation information, estimating residual flux linkage, and restoring initial control settings. However, for voltage source inverters with anti-parallel diodes, blocking the gate drive pulse only indicates that the power switch stops controlled conduction, and does not necessarily mean that the actual current in the motor stator winding disappears simultaneously. Since the electromagnetic energy stored in the stator winding needs to be released, the actual stator current may still form a freewheeling path through the anti-parallel diodes in the inverter bridge and the DC side after the pulse blocking, and continue to exist for a period of time. During this period, the stator current is still an actual input affecting the change in rotor flux linkage state; therefore, when the residual flux linkage calculation directly uses the gate blocking moment as the boundary for the stator current to change from non-zero to zero, its calculation boundary may be earlier than the actual stator current disappearance boundary, thus causing some of the actual electromagnetic evolution after gate blocking not to be reflected in the rotor flux linkage state used for restart.

[0006] Therefore, the existing technology still has the following technical gap: during the short-term power outage process after the inverter pulse blockade, there may be a deviation between the rotor flux state used to restore vector control and the electromagnetic state of the motor during the actual power outage. Especially when there is still stator freewheeling current after the pulse blockade, this deviation will be transmitted to the initial state of restart as the flux state during the power outage evolves, thereby increasing the risk of current and electromagnetic torque mutations during the recovery of control. Summary of the Invention

[0007] To address the technical problem in existing inverter instantaneous stop and restart processes where the actual electromagnetic state after pulse blocking is not continuously reflected in the initial rotor flux linkage state used for recovery vector control, leading to deviations in the rotor flux linkage state during restart and easily causing sudden changes in current and electromagnetic torque, this invention provides an inverter instantaneous stop and restart method based on flux linkage state reconstruction. The method includes: responding to a real-time DC bus voltage drop to an undervoltage action threshold, blocking the inverter pulse, recording the pulse blocking time, and latching the initial rotor flux linkage space vector; continuously acquiring motor three-phase stator data after pulse blocking. The stator freewheeling current is converted into a stator freewheeling current space vector. A stator freewheeling current zero-value determination is performed based on the stator freewheeling current space vector and the current zero-value tolerance. When the zero-value determination condition is met, the corresponding sampling time is determined as the stator freewheeling current zero-value time, and the stator freewheeling current space vector is continuously acquired until the pulse recovery time. When the DC bus real-time voltage recovers and the restart condition is met, the inverter pulse is locked, and the predetermined time for executing the inverter pulse recovery action is determined as the pulse recovery time. The pulse lock time to the pulse recovery time is then obtained. The rotor electric angular velocity during the power outage is determined. Starting with the initial rotor flux linkage space vector, the rotor flux linkage state is updated according to the stator freewheeling current space vector, the rotor electric angular velocity during the power outage, the rotor time constant, and the mutual inductance between the stator and rotor, based on the rotor flux linkage state equation including the stator current forcing term. When the stator freewheeling current has reached zero at the pulse recovery time, the stator current forcing term is retained until the stator freewheeling current reaches zero, and then set to zero and updated continuously from the stator freewheeling current reaches zero. Up to the pulse recovery time; if the stator freewheeling current zero value has not been determined by the pulse recovery time, maintain the stator current forcing term and update it to the pulse recovery time; determine the rotor flux linkage space vector obtained at the pulse recovery time as the reconstructed rotor flux linkage space vector; before releasing the inverter pulse blockade, write the reconstructed rotor flux linkage space vector into the inverter vector controller, and use the rotor flux linkage state corresponding to the reconstructed rotor flux linkage space vector as the initial state of the recovery vector control. After completing the writing of the rotor flux linkage state, release the inverter pulse blockade.

[0008] This invention, even after a frequency converter pulse blockade, still determines the boundary of the stator current's effect on the rotor flux linkage state based on the actually collected stator freewheeling current, and directly controls the retention and zeroing of the stator current forcing term in the rotor flux linkage state equation using this actual current boundary. Therefore, the detection result of the stator freewheeling current is not only used to determine whether the current has disappeared, but also serves as a control condition for changes in the rotor flux linkage state evolution relationship, enabling the rotor flux linkage state after the pulse blockade to be continuously updated along the actual electromagnetic state until the pulse recovery time. Compared to the method of directly using the gate blockade time as the stator current disappearance boundary, this invention avoids using a flux linkage evolution relationship with zero stator current in advance when the actual freewheeling current still exists, and directly uses the reconstructed rotor flux linkage space vector formed at the pulse recovery time as the initial state for recovery vector control. This reduces the deviation between the initial rotor flux linkage state of recovery control and the actual remaining electromagnetic state of the motor, lowering the risk of sudden changes in restart current and electromagnetic torque caused by this state deviation.

[0009] Preferably, the determination of the zero value of the stator freewheeling current based on the stator freewheeling current space vector and the zero value tolerance includes: calculating the amplitude of the stator freewheeling current space vector at each sampling time; comparing the amplitude of the stator freewheeling current space vector with the zero value tolerance; and determining the sampling time at which the amplitude of the first stator freewheeling current space vector after pulse blocking is not greater than the zero value tolerance as the zero value time of the stator freewheeling current.

[0010] This invention calculates the magnitude of the stator freewheeling current space vector at each sampling moment and determines the first sampling moment after pulse blocking where the magnitude is not greater than the current zero tolerance as the stator freewheeling current zero value moment. This makes the input switching boundary of the rotor flux linkage state equation correspond to the time position when the actual sampled current first enters the zero value range, avoiding the inconsistency between the boundary and the actual current state caused by using a fixed delay time as the freewheeling termination boundary.

[0011] Preferably, the determination of the zero-current tolerance includes: under the condition of zero-current calibration with no current at the inverter output terminal, obtaining multiple sets of three-phase stator current zero-value samples of the motor through the current sampling channel; performing the same Clarke transformation as during normal operation of the inverter on each set of three-phase stator current zero-value samples of the motor to obtain the corresponding zero-current space vector; calculating the amplitude of each zero-current space vector, and determining the maximum value among the amplitudes of each zero-current space vector obtained during the zero-current calibration process as the zero-current tolerance.

[0012] Preferably, determining the pulse recovery time includes: determining the control period for unlocking the inverter pulse blockade based on the pulse recovery action sequence specified by the frequency converter, and determining the time corresponding to the control period for unlocking the inverter pulse blockade as the pulse recovery time.

[0013] This invention determines the actual PWM recovery boundary corresponding to the control cycle of the inverter pulse blockade to be unblocked as the pulse recovery time, so that the update endpoint of the rotor flux state during the power outage is consistent with the time boundary of the actual recovery of the controlled pulse of the three-phase inverter bridge, avoiding the time boundary deviation caused by taking the earlier DC bus recovery time or the restart permission formation time as the flux reconfiguration endpoint.

[0014] Preferably, obtaining the rotor electrical angular velocity during the power outage includes: obtaining the mechanical angular velocity corresponding to each sampling moment during the pulse blockade period through the existing speed detection function of the frequency converter; calculating the product of the rotor pole pairs and the mechanical angular velocity to obtain the rotor electrical angular velocity at the corresponding sampling moment.

[0015] Preferably, the rotor flux linkage state equation including the stator current forcing term is expressed in a two-phase stationary coordinate system as follows: ; In the formula, express The instantaneous rate of change of the rotor flux linkage component over time; express The instantaneous rate of change of the rotor flux linkage component over time; and These are the rotor flux linkage space vectors in the two-phase stationary coordinate system. Shaft rotor flux component and Rotor flux linkage component; and These are the space vectors of the stator freewheeling current in the two-phase stationary coordinate system. Axis current components and Axis current components; The rotor's electric angular velocity; The rotor time constant; For mutual inductance between stator and rotor; , The stator current forcing terms are respectively in shaft and Components on the axis.

[0016] Preferably, when the zero value of the stator freewheeling current is earlier than the pulse recovery time, the stator current forcing term in the rotor flux linkage state equation is set to zero from the zero value of the stator freewheeling current, and the rotor flux linkage amplitude and rotor flux linkage electrical angle at the pulse recovery time are calculated according to the free evolution relationship of the rotor flux linkage: ; In the formula, This is the moment when the stator freewheeling current reaches zero. This is the pulse recovery time; and These are the rotor flux amplitude and rotor flux electrical angle at the moment when the stator freewheeling current is zero; and These are the rotor flux amplitude and rotor flux electrical angle at the pulse recovery moment, respectively; It is a natural exponential function; The rotor time constant; For a moment The rotor's electric angular velocity; This is the time integration variable.

[0017] After the stator freewheeling current reaches zero, this invention sets the stator current forcing term to zero and updates the rotor flux amplitude according to the exponential decay relationship corresponding to the rotor time constant, and updates the rotor flux electrical angle according to the time integral of the rotor electrical angular velocity during the power-off period. This ensures that the flux amplitude decay and spatial rotation after the forced input disappears correspond to the rotor electromagnetic decay law and the actual rotor rotation process, respectively. As a result, the free evolution stage continues to advance continuously from the flux state already formed at the stator freewheeling current zero point to the pulse recovery point.

[0018] Preferably, determining the rotor flux space vector at the pulse recovery time includes: calculating based on the rotor flux amplitude and rotor flux electrical angle at the pulse recovery time. Shaft rotor flux component and Rotor flux linkage components: ; In the formula, This is the pulse recovery time; , These are the rotor flux amplitude and rotor flux electrical angle at the pulse recovery moment, respectively; , These are the pulse recovery times. Shaft rotor flux component and The rotor flux linkage component of the shaft; The shaft rotor flux component and the The rotor flux linkage components constitute the rotor flux linkage space vector obtained at the pulse recovery time.

[0019] Preferably, writing the reconstructed rotor flux linkage space vector into the inverter vector controller includes: when the inverter vector controller uses the rotor flux linkage components in a two-phase stationary coordinate system as the rotor flux linkage state, writing the reconstructed rotor flux linkage space vector... Shaft rotor flux component and The rotor flux linkage component is directly written into the corresponding rotor flux linkage state; when the frequency converter vector controller uses the rotor flux linkage amplitude and rotor flux linkage electrical angle as the rotor flux linkage state, it reconstructs the rotor flux linkage space vector... Shaft rotor flux component and The rotor flux linkage components are calculated to recover the flux linkage amplitude and the recovery flux linkage electrical angle, and the recovered flux linkage amplitude and the recovered flux linkage electrical angle are written into the corresponding rotor flux linkage state.

[0020] This invention directly writes the reconstructed rotor flux linkage space vector into the actual internal rotor flux linkage state form used in the inverter vector controller. axis, The rotor flux linkage component state is converted into rotor flux linkage amplitude and rotor flux linkage electrical angle and then written into the corresponding state, so that the same reconstruction result can be matched with the existing flux linkage state interface of the vector controller, avoiding the introduction of additional state transition deviations due to the re-establishment of another set of initial flux linkage states during recovery.

[0021] Preferably, updating the rotor flux linkage state according to the rotor flux linkage state equation including the stator current forcing term includes: within each sampling period in which the stator current forcing term is retained, updating the rotor flux linkage state by current sampling period. To determine the step size, an explicit Euler discretization method is used, based on the first step... Calculation of rotor flux linkage state at the sampling time. Rotor flux linkage state at each sampling time: ; In the formula, , The first The rotor flux linkage space vector at each sampling time in the two-phase stationary coordinate system Shaft rotor flux component and Rotor flux linkage component; For the first Each sampling time The instantaneous rate of change of the rotor flux linkage component over time; For the first Each sampling time The instantaneous rate of change of the rotor flux linkage component over time; , The first The rotor flux linkage space vector at each sampling time in the two-phase stationary coordinate system Shaft rotor flux component and Rotor flux linkage component; This is the current sampling period.

[0022] This invention uses the current sampling period as the discrete step length to convert the continuous rotor flux linkage state equation into a recursive relationship executed on a sampling cycle basis using an explicit Euler method. This allows the stator freewheeling current space vector, rotor electric angular velocity, and current rotor flux linkage state obtained at each sampling moment to jointly form the rotor flux linkage state at the next sampling moment within the same control cycle. This ensures that the rotor flux linkage state update is consistent with the existing current sampling and control interruption timing of the frequency converter. At the same time, each set of sampled data only participates in the corresponding state update once, eliminating the need to replay historical sampled data during pulse recovery. This facilitates continuous and real-time execution of rotor flux linkage state reconstruction during power outages in the digital controller.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention uses the actual stator freewheeling current state after pulse blocking as an important boundary condition for the evolution of rotor flux linkage state during power outage. This ensures that the forced response when the stator current still exists and the free evolution after the stator current enters the zero value range are continuously connected in the same rotor flux linkage state chain. This state chain is then updated to the actual pulse recovery time as the initial flux linkage state for recovery vector control. Furthermore, by using a zero-value judgment benchmark corresponding to the actual current sampling channel, a time boundary corresponding to the actual PWM recovery action, and a state writing method that matches the internal state form of the vector controller, the consistency and executability of the rotor flux linkage state boundary during instantaneous stop and restart are improved. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating an inverter instantaneous stop and restart method based on flux linkage state reconstruction according to the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] This embodiment takes a voltage source type three-phase frequency converter driving an AC squirrel-cage induction motor as an example. The frequency converter includes a DC bus, a DC bus voltage sampling channel, a three-phase current sampling channel, an encoder interface, a main controller, a gate drive circuit, a three-phase inverter bridge, and a vector controller. The power switching transistors of the three-phase inverter bridge are configured with anti-parallel diodes, and the motor adopts rotor flux-oriented vector control.

[0028] During the instantaneous stop, the inverter control power supply maintains normal operation of the main controller, DC bus voltage sampling channel, three-phase current sampling channel and encoder interface, enabling the main controller to continue to complete voltage monitoring, current sampling, speed sampling, timing and rotor flux status updates.

[0029] This embodiment directly uses the control benchmark and motor parameters determined during normal operation of the frequency converter. The undervoltage protection threshold is determined by the existing undervoltage protection configuration of the frequency converter. The current control interruption cycle is specified by the frequency converter control program. The main controller performs a three-phase stator current sampling once during each current control interruption, and the time interval between two adjacent current samples is used as the current sampling cycle. Rotor time constant mutual inductance between stator and rotor and rotor pole pairs The parameters are determined by the vector controller motor model parameter set corresponding to the current motor. In addition, the vector controller specifies a two-phase stationary coordinate system, Clarke transformation proportional relationship, and positive direction of rotor electric angular velocity. This embodiment adopts the coordinate definition, transformation proportional relationship, and positive direction.

[0030] The zero-current tolerance is determined and stored by the zero-current calibration of the three-phase current sampling channel. The specific process is as follows: the zero-current calibration adopts the sampling number specified by the existing zero-current calibration process of the frequency converter; under the calibration condition that it is confirmed that there is no current at the output of the frequency converter, the three-phase current sampling channel synchronously collects multiple sets of three-phase current zero-value samples. The main controller performs the same Clarke transformation as during normal operation on each set of three-phase current zero-value samples and calculates the amplitude of the corresponding zero-current space vector; the main controller determines the maximum value among all zero-current space vector amplitudes obtained by the zero-current calibration as the zero-current tolerance; therefore, the zero-current tolerance is not recalculated during subsequent operation, and the already determined zero-current tolerance is used as the benchmark for judging the zero value of the stator freewheeling current.

[0031] The main controller uses the same hardware control clock to represent the pulse blocking moment, the current sampling moment, the stator freewheeling current zero value moment, and the pulse recovery moment: (The clock is represented by the first...) The sampling time of each current control cycle is represented as follows: Within each current control cycle after a pulse blockade, the main controller first executes step S2 to form the stator freewheeling current space vector at the current sampling moment and completes the zero value judgment, then executes step S3 to form the rotor electric angular velocity at the current sampling moment, and then executes step S4 to calculate the rotor flux state at the next sampling moment based on the currently saved rotor flux state and the current and speed results formed in this cycle.

[0032] In this embodiment, the vector controller is based on a two-phase stationary coordinate system. Shaft rotor flux component and The rotor flux linkage component is used as the internal rotor flux linkage state. Therefore, in step S1, the two rotor flux linkage components are directly latched. After the pulse blockade, in each current control cycle, the main controller sequentially executes the stator current sampling and zero value judgment in step S2, the rotor speed sampling in step S3, and the rotor flux linkage state update in step S4. The above three actions are executed continuously in the same control loop until step S5 releases the pulse blockade. In step S5, the two rotor flux linkage components finally formed in step S4 are directly written back to the vector controller.

[0033] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0034] See Figure 1 This is a flowchart of a method for instantaneous stop and restart of a frequency converter based on flux linkage state reconfiguration, provided by an embodiment of the present invention. Figure 1 As shown, the method may include:

[0035] S1. Monitor the real-time voltage of the DC bus, block the inverter pulses, and latch the initial rotor flux space vector.

[0036] During normal operation, the DC bus voltage sampling channel collects the real-time DC bus voltage according to the specified control cycle. The main controller compares the real-time DC bus voltage with the determined undervoltage action threshold. When the real-time DC bus voltage first drops to the undervoltage action threshold, the main controller reads the data currently being used by the vector controller in the current control cycle. Shaft rotor flux component and Shaft rotor flux component The two rotor flux linkage components constitute the initial rotor flux linkage space vector. The main controller simultaneously reads the hardware control clock and records the pulse blocking action corresponding to the current control cycle as the pulse blocking time. .

[0037] If the vector controller stores the rotor flux linkage state, which includes the rotor flux linkage amplitude and the rotor flux linkage electrical angle, then it should be converted into a two-phase stationary coordinate system. Shaft rotor flux component and Shaft rotor flux component :

[0038]

[0039]

[0040] In the formula, , They are respectively Shaft rotor flux component and Rotor flux linkage component of shaft, For rotor flux amplitude, The rotor flux linkage is the electrical angle.

[0041] It should be noted that the initial rotor flux linkage space vector is not recalculated after it is formed, and the first state update in the subsequent step S4 directly uses this initial rotor flux linkage space vector as the starting state.

[0042] It should be noted that the obtained initial rotor flux space vector is directly derived from the rotor flux state that participated in normal vector control before the instantaneous stop. It is not necessary to re-execute motor parameter identification or re-estimate a set of initial flux after the instantaneous stop. Therefore, the obtained initial rotor flux space vector is state latched. In this way, the first rotor flux state update during the power outage uses the same state reference as the normal vector control before the instantaneous stop, avoiding state jumps at the reconstruction starting point due to resetting the zero flux or using another set of initial states.

[0043] After completing the recording of the initial rotor flux space vector and pulse blocking time, the main controller immediately sends a pulse blocking command to the gate drive circuit, and the gate drive circuit stops outputting drive pulses to the three-phase inverter bridge power switch tubes; after the power switch tubes stop being controlled to conduct, the main controller enters the cycle-by-cycle state update process during the power outage period consisting of steps S2 to S4.

[0044] S2. After pulse blocking, continuously acquire the space vector of stator freewheeling current and determine the time of zero value of stator freewheeling current based on the current zero value tolerance.

[0045] It should be noted that after the gate drive circuit stops outputting drive pulses, the electromagnetic energy stored in the stator windings will not immediately become zero due to the disappearance of the gate drive signal. The three-phase stator current of the motor may still continue to flow through the anti-parallel diodes of the three-phase inverter bridge. Therefore, pulse blocking only indicates that the three-phase inverter bridge has stopped its controlled switching, and does not indicate that the stator current effect in the rotor flux linkage state equation has disappeared. To ensure that subsequent rotor flux linkage state updates continue to use the actual existing stator current, the three-phase current sampling channel remains operational after pulse blocking.

[0046] Specifically, in the first Each sampling time The three-phase current sampling channels simultaneously acquire the U-phase stator current at the same moment. V-phase stator current and W-phase stator current The main controller performs a prescribed Clarke transformation on the three-phase stator currents to calculate the stator freewheeling current space vector. Axis current components and Axis current components :

[0047]

[0048]

[0049] In the formula, , The first The space vector of stator freewheeling current at each sampling time Axis current components and Axis current components; , , The first The U-phase stator current, V-phase stator current, and W-phase stator current at each sampling time; the two components obtained. and Constituting the first Stator freewheeling current space vector at each sampling time .

[0050] The main controller is based on two current components. and Calculate the magnitude of the stator freewheeling current space vector. :

[0051]

[0052] In the formula, For the first The magnitude of the stator freewheeling current space vector at each sampling time; , The first The space vector of stator freewheeling current at each sampling time Axis current components and The shaft current component; thus, at the same sampling moment, only one set of stator freewheeling current space vectors and the amplitude of one stator freewheeling current space vector are formed.

[0053] The main controller from the pulse blocking moment The process begins by comparing the magnitude of the stator freewheeling current space vector with the zero-current tolerance in each sampling cycle. When the magnitude of the stator freewheeling current space vector is greater than the zero-current tolerance, the current stator freewheeling current space vector indicates that stator freewheeling still exists, and the stator current forcing term is retained in the state update after this sampling moment in subsequent step S4. When the magnitude of the stator freewheeling current space vector is less than or equal to the zero-current tolerance for the first time, the sampling moment when the magnitude of the stator freewheeling current space vector is not greater than the zero-current tolerance is determined as the stator freewheeling current zero-value moment. .

[0054] It should be noted that the above processing makes the switching boundary of the subsequent stator current forcing term determined by the current state actually measured by the current sampling channel. The stator freewheeling current space vector and the stator freewheeling current zero value moment formed in step S2 directly enter step S4 to determine whether the current rotor flux linkage state update continues to include the stator current forcing term.

[0055] S3. Obtain the rotor electric angular velocity used for rotor flux electric angle propulsion during the power outage, and determine the pulse recovery time.

[0056] After completing the current processing at the current sampling moment in step S2, the encoder interface provides the motor mechanical angular velocity for the same control cycle according to the specified speed sampling method. .

[0057] The main controller determines the number of rotor pole pairs. Calculate the first Rotor electric angular velocity at each sampling time :

[0058]

[0059] In the formula, For the first The rotor electric angular velocity at each sampling moment; For the first The mechanical angular velocity of the motor at each sampling moment; denoted as the number of rotor pole pairs.

[0060] It should be noted that the obtained rotor electrical angular velocity and the stator freewheeling current space vector formed in step S2 use the same hardware control clock, therefore they correspond to the same sampling time, and the subsequent step S4 directly uses the rotor electrical angular velocity. Advance the current rotor flux linkage state.

[0061] The inverter has a built-in instantaneous stop and restart logic that provides a restart permission status and specifies the PWM update timing of the recovery pulse; in this embodiment, when the main controller is at the sampling time Upon first detection of a valid restart permission state, the main controller continues to keep the gate drive circuit in a pulse-blocked state and completes one state update in steps S2, S3, and S4 during the current control cycle. The existing PWM output timing recovers the PWM update boundary drive pulse after this state update, and the main controller records the unified control time corresponding to the PWM update boundary as the pulse recovery time. Furthermore, the obtained pulse recovery time represents the time boundary at which the three-phase inverter bridge is actually prepared to recover the controlled pulse.

[0062] Therefore, before the pulse blockade is lifted in the subsequent step S5, the subsequent step S4 can continuously update the rotor flux state to the pulse recovery time. Then, the reconstruction result at that moment is written to the vector controller to avoid the magnetic flux reconstruction endpoint being earlier than the actual pulse recovery boundary.

[0063] S4. Update the rotor flux state in segments with the zero value of the stator freewheeling current as the boundary, and form the reconstructed rotor flux space vector at the pulse recovery time.

[0064] Specifically, when the main controller first enters step S4 in this instantaneous stop recovery process, it directly uses the rotor time constant determined by the current vector controller motor model parameter set. Mutual inductance between stator and rotor The same sampling method will continue to be used in subsequent sampling cycles following this momentary pause recovery procedure. and .

[0065] The state relationship in this step is obtained based on the rotor voltage equation and rotor flux linkage equation of the AC squirrel-cage induction motor in a two-phase stationary coordinate system: With the AC squirrel-cage rotor winding short-circuited, the applied voltage to the rotor is zero. Therefore, the rotor voltage equation is expressed as:

[0066]

[0067] In the formula, For rotor resistance; This is the rotor current space vector converted to the same parameter system; is the rotor flux linkage space vector in the two-phase stationary coordinate system; The rotor's electric angular velocity; The imaginary unit; Let be the instantaneous rate of change of the rotor flux linkage space vector in the two-phase stationary coordinate system with time.

[0068] The rotor flux linkage equation is expressed as:

[0069]

[0070] In the formula, This represents the rotor flux linkage space vector in a two-phase stationary coordinate system. For mutual inductance between stator and rotor, This represents the space vector of stator current in a two-phase stationary coordinate system. Indicates rotor self-inductance, This represents the rotor current space vector converted to the same parameter system.

[0071] Based on the above rotor flux linkage equation, the rotor current space vector in the rotor voltage equation is eliminated. ,get:

[0072]

[0073] And Substituting the values, we obtain the rotor flux linkage state equation:

[0074]

[0075] In the formula, Let be the instantaneous rate of change of the rotor flux linkage space vector in the two-phase stationary coordinate system over time; is the rotor flux linkage space vector in the two-phase stationary coordinate system; The rotor time constant; The rotor's electric angular velocity; The imaginary unit; For mutual inductance between stator and rotor; This represents the space vector of stator current in a two-phase stationary coordinate system; This is the stator current forcing term, which reflects the effect of the actual stator current on the change in rotor flux linkage state through the mutual inductance between the stator and rotor.

[0076] It should be noted that after the pulse blockade, as long as the zero value of the stator freewheeling current has not been determined in step S2, step S4 must retain the actual sampled stator freewheeling current in the rotor flux linkage state update, and the stator current forcing term will still participate in the rotor flux linkage state change; only after the zero value of the stator freewheeling current is determined in step S2, the stator current forcing term will be set to zero in subsequent state updates from the zero value of the stator freewheeling current; if the zero value of the stator freewheeling current has not been detected by the pulse recovery time, the actual measured stator freewheeling current space vector will be used to retain the stator current forcing term throughout the reconstruction interval.

[0077] Therefore, the freewheeling interval and the free evolution interval after the stator freewheeling current is zero can be covered under the same rotor flux linkage state relationship; if the stator freewheeling current is not detected as of the pulse recovery time, it will not enter the stator current forced term zeroing interval.

[0078] The space vector equation is then expanded as follows: shaft and The two real-valued state equations of the shaft, in the two-phase stationary coordinate system used in this embodiment, are expanded as follows:

[0079]

[0080]

[0081] In the formula, express The instantaneous rate of change of the rotor flux linkage component over time; express The instantaneous rate of change of the rotor flux linkage component over time; and These are the rotor flux linkage space vectors in the two-phase stationary coordinate system. Shaft rotor flux component and Rotor flux linkage component; and These are the space vectors of the stator freewheeling current in the two-phase stationary coordinate system. Axis current components and Axis current components; The rotor's electric angular velocity; The rotor time constant; For mutual inductance between stator and rotor; , The stator current forcing terms are respectively in shaft and Components on the axis.

[0082] If the stator freewheeling current has not yet been recorded in step S2, the main controller uses the currently saved value. Shaft rotor flux component and Shaft rotor flux component As the starting value for this state update, based on the stator freewheeling current space vector formed in step S2... Axis current components and Axis current components and the rotor electric angular velocity formed in step S3 The rotor flux linkage state at the next sampling time is calculated using explicit Euler relations:

[0083]

[0084]

[0085] in, The first calculation based on the rotor flux linkage state equation Each sampling time The instantaneous rate of change of the rotor flux linkage component over time; The first calculation based on the rotor flux linkage state equation Each sampling time The instantaneous rate of change of the rotor flux component over time.

[0086] Instantaneous rate of change and Substituting the corresponding rotor flux linkage state equation, we obtain the rotor flux linkage state at the next sampling time as follows:

[0087]

[0088]

[0089] In the formula, , The first The rotor flux linkage space vector at each sampling time in the two-phase stationary coordinate system Shaft rotor flux component and Rotor flux linkage component; , The first The rotor flux linkage space vector at each sampling time in the two-phase stationary coordinate system Shaft rotor flux component and Rotor flux linkage component; The current sampling period; The rotor time constant; For the first The rotor electric angular velocity at each sampling moment; For mutual inductance between stator and rotor; , The first The space vector of stator freewheeling current at each sampling time Axis current components and Axial current component.

[0090] During the first state update, the initial rotor flux linkage space vector formed in step S1 is used. The two rotor flux components and As and Each time a state update is completed, the main controller replaces the two rotor flux linkage components of the previous sampling moment with the two newly obtained rotor flux linkage components; the next sampling period only uses the update result as the new current rotor flux linkage state, without recalculating the completed historical state; thus, the stator freewheeling current space vector formed at each sampling moment is only used as a forced input in one rotor flux linkage state update of the corresponding control period.

[0091] When step S2 first determines the zero value of the stator freewheeling current At the moment when the stator freewheeling current is zero The corresponding current Shaft rotor flux component and Shaft rotor flux component It is formed by the state update of the previous sampling period; at this moment, the main controller stops using the subsequent current sampling value as the stator current forcing term, and according to the zero value of the stator freewheeling current. The two corresponding current rotor flux components and Calculate the rotor flux linkage amplitude at the moment when the stator freewheeling current is zero. and rotor flux electrical angle :

[0092]

[0093]

[0094] In the formula, This is the moment when the stator freewheeling current reaches zero. , These are the moments when the stator freewheeling current is zero. The rotor flux amplitude and rotor flux electrical angle; , The rotor flux linkage space vector in the two-phase stationary coordinate system at the moment when the stator freewheeling current is zero. Shaft rotor flux component and The rotor flux linkage component; the amplitude of the rotor flux linkage and rotor flux electrical angle Only at the moment when the stator freewheeling current is zero It is formed once and serves as the starting state for the free evolution phase.

[0095] From the moment when the stator freewheeling current is zero At this point, the stator current forcing term is set to zero, and the rotor flux linkage state equation enters a free evolution state. In continuous time, the rotor flux linkage amplitude decays exponentially according to the rotor time constant between the moment the stator freewheeling current reaches zero and the moment of pulse recovery. The rotor flux linkage electrical angle advances according to the time integral of the rotor electrical angular velocity during the power-off period. Therefore, the rotor flux linkage amplitude and rotor flux linkage electrical angle at the moment of pulse recovery satisfy the following:

[0096]

[0097]

[0098] In the formula, At the moment when the stator freewheeling current is zero, The pulse recovery time, and These represent the rotor flux linkage amplitude and rotor flux linkage electrical angle at the moment when the stator freewheeling current is zero. and These represent the rotor flux amplitude and rotor flux electrical angle at the pulse recovery time, respectively. It is a natural exponential function. The rotor time constant, For a moment The rotor electric angular velocity, This is the time integration variable.

[0099] At the moment when the stator freewheeling current is zero Subsequently, the stator current forcing term is zero, and the rotor flux linkage amplitude is only controlled by the free decay relationship corresponding to the rotor time constant. To ensure that the digital control process continues to execute in the order of generating the next state from the previous state, the main controller calculates the rotor flux linkage amplitude at the next sampling time based on the rotor flux linkage amplitude at the previous sampling time in each subsequent sampling period. In the free evolution stage, the rotor flux linkage amplitude is equivalently represented by an exponential decay according to the rotor time constant in continuous time.

[0100]

[0101] In the formula, For the first The rotor flux amplitude at each sampling time; For the first The rotor flux amplitude at each sampling time; It is a natural exponential function; The current sampling period; is the rotor time constant.

[0102] The rotor flux electrical angle is still determined by the rotor's physical rotation. To ensure that the state update in each control cycle uses only the currently acquired rotor electrical angular velocity, the main controller, according to step S3, in the... The rotor electric angular velocity formed at each sampling time According to the current sampling period The rotor flux electrical angle at the next sampling time:

[0103]

[0104] In the formula, For the first The rotor flux electrical angle at each sampling time; For the first The rotor flux electrical angle at each sampling time; For the first The rotor electric angular velocity at each sampling moment; This is the current sampling period.

[0105] Furthermore, the first amplitude and electrical angle updates during the free evolution phase were performed at the moment when the stator freewheeling current was at its zero value. rotor flux amplitude and rotor flux electrical angle As the starting value, the rotor flux amplitude is calculated using the above continuous-time exponential decay relationship, and the rotor electrical angular velocity during the power outage is integrated over time to obtain the flux electrical angle at the pulse recovery time. After each update, the main controller replaces the amplitude and electrical angle of the previous sampling time with the newly obtained rotor flux amplitude and electrical angle, and subsequent sampling cycles continue to advance using the current results.

[0106] At the pulse recovery time If up to the pulse recovery time The moment when the stator freewheeling current reaches zero has been recorded. Then when Earlier At that time, the main controller had been continuously updated to the free evolution stage. rotor flux amplitude and rotor flux electrical angle ;when and When they are at the same time, the main controller directly... The corresponding rotor flux amplitude and rotor flux electrical angle As Calculate the rotor flux amplitude and rotor flux electrical angle at time t, and calculate the two rotor flux components at the pulse recovery time:

[0107]

[0108]

[0109] In the formula, This is the pulse recovery time; , The rotor flux linkage space vector at the pulse recovery moment in the two-phase stationary coordinate system are respectively Shaft rotor flux component and Rotor flux linkage component; The rotor flux amplitude at the pulse recovery moment; The rotor flux electrical angle is at the pulse recovery moment.

[0110] At this point, the two rotor flux components will be obtained and Constitutes the space vector of the reconstructed rotor flux linkage The object is formed once at the pulse recovery time. Step S5 directly uses the object and does not re-execute the amplitude, electrical angle or historical state reconstruction.

[0111] If the power grid recovers extremely quickly, up to the pulse recovery time... If step S2 has not yet detected and recorded the zero value of the stator freewheeling current, it indicates that the actual stator freewheeling current has not yet entered the zero-value tolerance within the entire pulse blocking interval. At this time, the main controller does not enter the free evolution stage, but continues to use the actual stator freewheeling current space vector formed in step S2 and the rotor electric angular velocity formed in step S3 to update the rotor flux linkage state to the pulse recovery time according to the aforementioned explicit Euler relation containing the stator current forcing term. and pulse recovery time The corresponding current Shaft rotor flux component and The rotor flux linkage components directly constitute the reconstructed rotor flux linkage space vector. .

[0112] For example, when the stator freewheeling current is zero Earlier than the pulse recovery time At that time, pulse blocking moment until the stator freewheeling current reaches zero value This corresponds to the freewheeling reconstruction interval that retains the stator current forcing term, at the moment when the stator freewheeling current is zero. To the pulse recovery time This corresponds to the free evolution interval where the stator current forcing term is zero; when and When the same time period is reached, the continuous flow reconstruction interval extends to The duration of the free evolution interval is zero; when it ends Not yet formed At that time, the freewheeling reconstruction interval extends directly to the pulse recovery time. .

[0113] S5. Write the reconstructed rotor flux space vector into the inverter vector controller and restore vector control with the corresponding rotor flux state.

[0114] When the inverter vector controller uses the rotor flux linkage amplitude and rotor flux linkage electrical angle as the flux linkage state, it writes the amplitude of the reconstructed rotor flux linkage space vector into the corresponding flux linkage amplitude state, writes the electrical angle of the reconstructed rotor flux linkage space vector into the corresponding flux linkage electrical angle state, and aligns the direct axis of the field orientation coordinate system with this electrical angle; when the inverter vector controller uses... shaft and When the shaft flux linkage component is used as the flux linkage state, the two components of the reconstructed rotor flux linkage space vector are directly written.

[0115] The vector controller in this embodiment is based on Shaft rotor flux component and The rotor flux linkage component is used as the internal rotor flux linkage state; therefore, before the PWM output action corresponding to the pulse recovery moment, the main controller reconstructs the rotor flux linkage space vector formed in step S4. The two rotor flux linkage components are directly written into the corresponding rotor flux linkage state of the vector controller.

[0116] After the rotor flux linkage state is written, the main controller sends a command to the gate drive circuit to release the pulse blockade. The gate drive circuit resumes outputting drive pulses to the three-phase inverter bridge power switch according to the specified PWM output timing. The vector controller continues to execute the existing vector control from the reconstructed rotor flux linkage state.

[0117] Since the rotor flux state before pulse recovery directly uses the rotor flux state continuously updated during the power outage, the recovery control does not need to be re-initialized from zero flux or directly from the moment of pulse blockade using the free evolution result with zero stator current, thereby reducing the deviation between the initial flux amplitude and electrical angle of restart and the actual remaining electromagnetic state of the motor.

[0118] For example, for a four-pole asynchronous motor, the number of rotor pole pairs Current sampling period Rotor time constant mutual inductance between stator and rotor The initial rotor flux space vector formed at the pulse blocking moment is: Its corresponding flux linkage amplitude is The magnetic flux electrical angle is .

[0119] The maximum value of all zero-current space vector magnitudes obtained in the existing zero-current calibration is Then the tolerance for zero current is determined as .

[0120] Using the sampling point corresponding to the pulse blocking moment as The five sampling times starting from the pulse blocking moment are as follows: , , , and The corresponding stator freewheeling current space vector is taken in sequence. , , , and .exist At the sampling time, the amplitude of the stator freewheeling current space vector is The first time is no greater than Therefore, the main controller will Record the moment when the stator freewheeling current is zero. .

[0121] Encoder interface in to The internal mechanical speed is continuously acquired, and when the motor mechanical speed changes from... Linear change to The main controller calculates the corresponding rotor electric angular velocity based on the motor mechanical speed and rotor pole pair number obtained at each sampling time, and the mechanical speed... With the mechanical angular velocity of the motor The conversion relationship between them is Rotor electric angular velocity With the mechanical angular velocity of the motor The conversion relationship between them is Then the rotor electric angular velocities near the pulse blocking time and the pulse recovery time are respectively and .

[0122] exist to Within the freewheeling reconstruction interval, the main controller performs explicit Euler state updates cycle by cycle using the space vectors of the first four non-zero stator freewheeling currents and the rotor electrical angular velocity at the same sampling moment. After four state updates are completed... The corresponding rotor flux amplitude is The rotor flux linkage electrical angle is The amplitude and electrical angle are in It is formed once and serves as the starting state for subsequent stages of free evolution.

[0123] exist to Within the free evolution range, the main controller calculates the rotor flux amplitude for the next sampling moment cycle by cycle based on the rotor flux amplitude at the previous sampling moment, and advances the rotor flux electrical angle for the next sampling moment according to the current sampling period based on the rotor electrical angular velocity already obtained at the current sampling moment. When the existing instantaneous stop restart logic is in When the corresponding PWM update boundary recovery pulse is applied, the amplitude of the reconstructed rotor flux is obtained. The reconstructed rotor flux linkage electrical angle is The main controller calculates the reconstructed rotor flux linkage space vector based on this amplitude and electrical angle. After directly writing the two rotor flux components into the corresponding rotor flux state of the vector controller, the pulse blockade is released.

[0124] As a comparison, under the condition that other parameters, encoder speed samples, and numerical update methods are kept the same, only the values ​​from 0 to... The stator current forcing term within the freewheeling reconstruction interval is set to zero, and the rotor flux linkage state is updated within this interval using the same explicit Euler relation as in this embodiment; The calculation continues using the same free evolution relationship as in this embodiment until... The obtained flux linkage amplitude is The rotor flux linkage electrical angle is .

[0125] Since the two sets of calculations above use the same motor parameters, encoder speed samples, and numerical update methods, they are both within the range of 0 to... The difference within the freewheeling reconstruction interval lies solely in whether or not the stator current forcing term corresponding to the actual stator freewheeling current is retained. Therefore, the difference in rotor flux amplitude and rotor flux electrical angle formed at the pulse recovery moment between the two sets of results reflects the influence of the stator current forcing term on the evolution of the rotor flux state within this freewheeling interval. This comparison indicates that the actual stator freewheeling current boundary formed in step S2 needs to enter step S4 as a switching condition for the stator current forcing term.

[0126] Another boundary case is when the restart permission state is already valid before the stator freewheeling current reaches the current zero tolerance. In this case, the main controller still executes steps S2, S3, and S4 in the existing sequence until the corresponding pulse recovery time. ; due to the end Before the stator freewheeling current reaches zero, step S4 does not proceed to the free evolution stage, but instead directly... The corresponding current Shaft rotor flux component and The rotor flux linkage component of the shaft is determined as the reconstructed rotor flux linkage space vector.

[0127] In another implementation of the vector controller, if the vector controller uses flux linkage amplitude and flux linkage electrical angle as the internal rotor flux linkage state, then steps S1 to S4 still form the same reconstructed rotor flux linkage space vector according to the above-described ordinary implementation path; only before writing the state in step S5, the main controller calculates the recovered flux linkage amplitude and recovered flux linkage electrical angle once based on the two rotor flux linkage components of the reconstructed rotor flux linkage space vector:

[0128]

[0129]

[0130] The main controller writes the recovery flux amplitude and recovery flux electrical angle into the corresponding rotor flux state specified by the vector controller, and then releases the pulse blockade according to the same pulse recovery timing sequence.

[0131] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for instantaneous stop and restart of a frequency converter based on flux linkage state reconfiguration, characterized in that, include: In response to the DC bus real-time voltage drop to the undervoltage action threshold, the inverter pulse is blocked, the pulse blocking time is recorded, and the initial rotor flux linkage space vector is latched. After the pulse blockade, the three-phase stator current of the motor is continuously collected and transformed into a stator freewheeling current space vector. The stator freewheeling current zero value determination is performed according to the stator freewheeling current space vector and the current zero value tolerance. When the zero value determination condition is met, the corresponding sampling time is determined as the stator freewheeling current zero value time, and the stator freewheeling current space vector is continuously collected until the pulse recovery time. Once the DC bus real-time voltage recovers and meets the restart conditions, the inverter pulse is locked, the time when the inverter pulse recovery action is scheduled to be executed is determined as the pulse recovery time, and the rotor electric angular velocity during the power outage period between the pulse lock time and the pulse recovery time is obtained. Starting with the initial rotor flux linkage space vector as the initial state, the rotor flux linkage state is updated according to the stator freewheeling current space vector, the rotor electrical angular velocity during the power-off period, the rotor time constant, and the mutual inductance between the stator and rotor, based on the rotor flux linkage state equation including a stator current forcing term. When the stator freewheeling current has been determined to be zero by the pulse recovery time, the stator current forcing term is retained until the stator freewheeling current reaches zero, and then set to zero and updated until the pulse recovery time. When the stator freewheeling current has not been determined by the pulse recovery time, the stator current forcing term is retained and updated until the pulse recovery time. The rotor flux linkage space vector obtained at the pulse recovery time is determined as the reconstructed rotor flux linkage space vector. Before unlocking the inverter pulse blockade, the reconstructed rotor flux linkage space vector is written into the inverter vector controller, and the rotor flux linkage state corresponding to the reconstructed rotor flux linkage space vector is used as the initial state for restoring vector control. After the rotor flux linkage state is written, the inverter pulse blockade is unlocked.

2. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 1, characterized in that, The stator freewheeling current zero-value determination is performed based on the stator freewheeling current space vector and the current zero-value tolerance, including: Calculate the magnitude of the stator freewheeling current space vector at each sampling time; The magnitude of the stator freewheeling current space vector is compared with the current zero tolerance. The sampling time at which the amplitude of the first stator freewheeling current space vector after the pulse blockade is not greater than the current zero tolerance is determined as the stator freewheeling current zero value time.

3. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 2, characterized in that, The determination of the zero-value tolerance of the current includes: Under the condition of zero-current calibration with no current at the inverter output, multiple sets of zero-value samples of the three-phase stator current of the motor are obtained through the current sampling channel. Perform the same Clarke transformation as when the frequency converter is running normally on the three-phase stator current zero value samples of each group of motors to obtain the corresponding zero current space vector; Calculate the magnitude of each zero-current space vector, and determine the maximum value among the magnitudes of each zero-current space vector obtained during the zero-current calibration process as the zero-current tolerance.

4. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 1, characterized in that, The determination of the pulse recovery time includes: The control period for unlocking the inverter pulse blockade is determined according to the pulse recovery action sequence specified by the inverter, and the time corresponding to the control period for unlocking the inverter pulse blockade is determined as the pulse recovery time.

5. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 1, characterized in that, Obtaining the rotor electrical angular velocity during the power outage includes: The mechanical angular velocity corresponding to each sampling moment during the pulse blockade is obtained by using the existing speed detection function of the frequency converter; the rotor electric angular velocity at the corresponding sampling moment is obtained by calculating the product of the rotor pole pair number and the mechanical angular velocity.

6. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 1, characterized in that, The rotor flux linkage state equation, which includes the stator current forcing term, is expressed in a two-phase stationary coordinate system as follows: ； ； In the formula, express The instantaneous rate of change of the rotor flux linkage component over time; express The instantaneous rate of change of the rotor flux linkage component over time; and These are the rotor flux linkage space vectors in the two-phase stationary coordinate system. Shaft rotor flux component and Rotor flux linkage component; and These are the space vectors of the stator freewheeling current in the two-phase stationary coordinate system. Axis current components and Axis current components; The rotor's electric angular velocity; The rotor time constant; For mutual inductance between stator and rotor; , The stator current forcing terms are respectively in shaft and Components on the axis.

7. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 6, characterized in that, When the zero point of the stator freewheeling current is earlier than the pulse recovery time, the stator current forcing term in the rotor flux linkage state equation is set to zero from the zero point of the stator freewheeling current, and the rotor flux linkage amplitude and rotor flux linkage electrical angle at the pulse recovery time are calculated according to the free evolution relationship of the rotor flux linkage. ； ； In the formula, This is the moment when the stator freewheeling current reaches zero. This is the pulse recovery time; and These are the rotor flux amplitude and rotor flux electrical angle at the moment when the stator freewheeling current is zero; and These are the rotor flux amplitude and rotor flux electrical angle at the pulse recovery time, respectively. It is a natural exponential function; The rotor time constant; For a moment The rotor's electric angular velocity; This is the time integration variable.

8. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 7, characterized in that, The determination of the rotor flux space vector at the pulse recovery moment includes: Calculate based on the rotor flux amplitude and rotor flux electrical angle at the pulse recovery time. Shaft rotor flux component and Rotor flux linkage components: ； ； In the formula, This is the pulse recovery time; , These are the rotor flux amplitude and rotor flux electrical angle at the pulse recovery time, respectively. , These are the pulse recovery times. Shaft rotor flux component and Rotor flux linkage component; The The shaft rotor flux component and the The rotor flux linkage components constitute the rotor flux linkage space vector obtained at the pulse recovery time.

9. The inverter instantaneous stop and restart method based on flux linkage state reconfiguration according to claim 1, characterized in that, Writing the reconstructed rotor flux space vector into the inverter vector controller includes: When the inverter vector controller uses the rotor flux linkage component in the two-phase stationary coordinate system as the rotor flux linkage state, it will reconstruct the rotor flux linkage space vector. Shaft rotor flux component and The rotor flux linkage component is directly written into the corresponding rotor flux linkage state. When the inverter vector controller uses the rotor flux linkage amplitude and rotor flux linkage electrical angle as the rotor flux linkage state, it reconstructs the rotor flux linkage space vector... Shaft rotor flux component and The rotor flux linkage components are calculated to recover the flux linkage amplitude and the recovery flux linkage electrical angle, and the recovered flux linkage amplitude and the recovered flux linkage electrical angle are written into the corresponding rotor flux linkage state.

10. A method for instantaneous stop and restart of a frequency converter based on flux linkage state reconfiguration according to claim 6, characterized in that, The step of updating the rotor flux linkage state according to the rotor flux linkage state equation containing the stator current forcing term includes: During each sampling period in which the stator current forcing term is retained, the current sampling period is used. To determine the step size, an explicit Euler discretization method is used, based on the first step... Calculation of rotor flux linkage state at the sampling time. Rotor flux linkage state at each sampling time: ； ； In the formula, , The first The rotor flux linkage space vector at each sampling time in the two-phase stationary coordinate system Shaft rotor flux component and Rotor flux linkage component; For the first Each sampling time The instantaneous rate of change of the rotor flux linkage component over time; For the first Each sampling time The instantaneous rate of change of the rotor flux linkage component over time; , The first The rotor flux linkage space vector at each sampling time in the two-phase stationary coordinate system Shaft rotor flux component and Rotor flux linkage component; This is the current sampling period.

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