Inverter power control method and system based on given current

Abstract

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.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inverter power control, and particularly relates to an inverter power control method and system based on current given. BACKGROUND

[0002] In a permanent magnet synchronous motor drive system, a system without electrolytic capacitor has a significantly increased bus voltage fluctuation due to a substantial reduction in capacitor capacity. The fluctuation usually presents harmonic characteristics such as double frequency and quadruple frequency, which seriously affects the power control accuracy and operation stability of the system. The traditional inverter power control method mainly adopts a fixed current given strategy, that is, fixed dq-axis current given values are calculated according to power instructions, and then power output is realized through current loop control. Due to the severe fluctuation of the bus voltage, the fixed current given cannot adapt to the voltage change, resulting in a large deviation between the actual output power and the expected power, and a decrease in power tracking accuracy. SUMMARY

[0003] The present application provides an inverter power control method and system based on current given, which realizes accurate prediction of the bus voltage and early correction of the current given, has a faster dynamic response than the traditional lag compensation, and improves the power control accuracy and operation stability.

[0004] In a first aspect, the present application provides an inverter power control method based on current given, which comprises: calculating a fluctuation compensation parameter based on the bus voltage and performing real-time compensation on a q-axis basic current to obtain a first q-axis current given; predicting the bus voltage of the next period and performing early correction on the first q-axis current given to obtain a second q-axis current given; generating a field-weakening d-axis current given based on the saturation state of the stator voltage, and performing low-pass filtering on the second q-axis current given and the field-weakening d-axis current given to obtain a dq-axis current instruction; generating a PWM driving signal corresponding to the dq-axis current instruction and controlling the inverter switch, and simultaneously collecting a power deviation signal to update the q-axis basic current.

[0005] In combination with the first aspect, in a first implementation manner of the first aspect of the present application, the calculation of the fluctuation compensation parameter based on the bus voltage and the real-time compensation on the q-axis basic current to obtain the first q-axis current given comprises: collecting the bus voltage according to the inverter switching frequency; setting a sliding window based on the fundamental period of the motor, and performing moving average calculation on the bus voltage by using the sliding window to obtain a bus voltage average value and simultaneously calculate a voltage fluctuation amplitude; extracting fluctuation components in the bus voltage and identifying strengths of second-harmonic and fourth-harmonic harmonic components to obtain voltage fluctuation spectrum data; determining a voltage fluctuation rate by using a ratio of the voltage fluctuation amplitude to the bus voltage average value, and generating a fluctuation compensation parameter in combination with the voltage fluctuation rate and the voltage fluctuation spectrum data; real-time compensating the q-axis basic current by using the fluctuation compensation parameter to obtain a first q-axis current given value.

[0006] In combination with the first aspect, in a second implementation manner of the first aspect of the application, the real-time compensating the q-axis basic current by using the fluctuation compensation parameter to obtain a first q-axis current given value includes: constructing a main compensation term and a harmonic compensation term based on the fluctuation compensation parameter, the main compensation term being modulated according to a square sine function of a motor rotor electric angle and a bus voltage fluctuation rate, and the harmonic compensation term being modulated according to a motor fundamental second-harmonic sine function; dividing a product of the motor electric angle frequency, the bus capacitance value and the bus voltage nominal value by the average output power, and multiplying the result by a coefficient of 0.5 to obtain a main compensation coefficient, and multiplying the main compensation coefficient by the main compensation term to obtain a main compensation current component; calculating a deviation power value of an actual output power from a power reference value, and updating a harmonic compensation coefficient according to the deviation power value to obtain an updated harmonic compensation coefficient; multiplying the updated harmonic compensation coefficient by the harmonic compensation term to obtain a harmonic compensation current component; superimposing the q-axis basic current, the main compensation current component and the harmonic compensation current component to obtain the first q-axis current given value.

[0007] In combination with the first aspect, in a third implementation manner of the first aspect of the application, the predicting a next-period bus voltage and calculating a prediction deviation, and the using the prediction deviation to pre-correct the first q-axis current given value to obtain a second q-axis current given value includes: calculating a bus charging current according to a current input power, and calculating an inverter output current according to dq-axis current given values and a current rotating speed; subtracting the bus charging current from the inverter output current to obtain a bus current difference value; multiplying the bus current difference value by a bus capacitance value to obtain a calculation result, and superimposing the calculation result on the bus voltage to obtain a next-period bus voltage; detecting a time variation rate of an electromagnetic torque to obtain a torque variation rate, calculating a load variation coefficient according to a ratio of the torque variation rate to a rated torque, and adjusting a prediction control gain based on the load variation coefficient to obtain an adaptive gain; A prediction deviation is generated according to the bus voltage of the next cycle, and a second q-axis current given value is calculated according to the prediction deviation and the first q-axis current given value using the adaptive gain.

[0008] In combination with the first aspect, in a fourth implementation manner of the first aspect of the application, the second q-axis current given value is calculated according to the prediction deviation and the first q-axis current given value using the adaptive gain, including: The difference between the bus voltage of the next cycle and a bus voltage reference value is taken as the prediction deviation; The prediction deviation is multiplied by the adaptive gain to obtain a target deviation value, and the target deviation value is multiplied by a q-axis current rated value to obtain a q-axis current correction amount; The q-axis current correction amount is subjected to algebraic addition operation with the first q-axis current given value to obtain the second q-axis current given value.

[0009] In combination with the first aspect, in a fifth implementation manner of the first aspect of the application, the field-weakening d-axis current given value is generated based on the stator voltage saturation state, and the second q-axis current given value and the field-weakening d-axis current given value are subjected to low-pass filtering to obtain the dq-axis current instruction, including: The stator voltage is calculated based on the square sum and square root operation of the dq-axis voltage components, and the maximum output voltage limit value is calculated according to the bus voltage; The voltage margin is obtained by performing difference operation between the maximum output voltage limit value and the stator voltage and then dividing the result by the maximum output voltage limit value, and the stator voltage saturation state is confirmed when the voltage margin is lower than a saturation judgment threshold value; If saturation occurs, the voltage difference between the stator voltage and a safe voltage boundary value is calculated, the voltage excess amount is determined as positive when the voltage difference is positive, and the voltage excess amount is set to zero when the voltage difference is negative or zero; The voltage excess amount is input into a field-weakening control gain to perform linear transformation, and the field-weakening d-axis current given value is output; The second q-axis current given value and the field-weakening d-axis current given value are subjected to low-pass filtering to obtain the dq-axis current instruction.

[0010] In combination with the first aspect, in a sixth implementation manner of the first aspect of the application, the voltage excess amount is input into a field-weakening control gain to perform linear transformation, and the field-weakening d-axis current given value is output, including: The voltage excess amount is taken as an input signal and input into a linear transformer, multiplied by a field-weakening control gain to perform proportional amplification, and a field-weakening current amplitude is obtained; According to the second q-axis current given, a maximum allowable power angle corresponding to an upper limit of a field weakening current is calculated, and an effective field weakening current amplitude is selected according to the field weakening current amplitude and the upper limit of the field weakening current; A mathematical sign transformation is performed on the effective field weakening current amplitude, a positive value is converted into a corresponding negative value, a field weakening current value is obtained, and the field weakening current value is output as a field weakening d-axis current given.

[0011] In combination with the first aspect, in a seventh implementation manner of the first aspect of the application, the low-pass filtering of the second q-axis current given and the field weakening d-axis current given to obtain the dq-axis current instruction comprises: A q-axis current change rate of the second q-axis current given and a d-axis current change rate of the field weakening d-axis current given are detected; When the q-axis current change rate exceeds a first preset limit value or the d-axis current change rate exceeds a second preset limit value, a slope limiting process is performed to obtain the dq-axis current given; According to the power change rate, a running state is judged, a target cutoff frequency is calculated as a first cutoff frequency in a steady state running, and the target cutoff frequency is calculated as a second cutoff frequency in a dynamic running, the first cutoff frequency being lower than the second cutoff frequency; The dq-axis current given is input into a first-order low-pass filter for filtering processing to obtain a filtered dq-axis current signal, and a cutoff frequency of the first-order low-pass filter is set as the target cutoff frequency; A time derivative of the dq-axis current given is calculated, the time derivative is multiplied by a filter time constant to generate a feedforward compensation signal, and the feedforward compensation signal is superimposed on the filtered dq-axis current signal to obtain a dq-axis current instruction.

[0012] In combination with the first aspect, in an eighth implementation manner of the first aspect of the application, the generation of a PWM driving signal corresponding to the dq-axis current instruction and the control of an inverter switch, and the acquisition of a power deviation signal to update the q-axis basic current comprise: A deviation operation is performed on a dq-axis current feedback value and the dq-axis current instruction to obtain a current deviation, and the current deviation is input into a PI controller for proportional and integral operation to obtain a dq-axis voltage control amount; A dq-axis decoupling compensation voltage is calculated according to a motor rotor position angle and motor parameters, and an addition operation is performed on the dq-axis decoupling compensation voltage and the dq-axis voltage control amount to obtain a dq-axis voltage given; The dq-axis voltage given is converted into a three-phase voltage instruction through coordinate transformation, a sector position and an action time are calculated by using an SVPWM modulation algorithm, a PWM driving signal is generated to control an inverter power switch tube to turn on and off; The instantaneous output power is calculated, a power deviation signal is obtained by subtracting the power reference value from the instantaneous output power, the power deviation signal is processed by using a power loop PI controller, a q-axis basic current regulation amount is obtained, and the q-axis basic current is updated.

[0013] In a second aspect, the application provides a current reference-based inverter power control system, comprising: A real-time compensation module is configured to calculate a fluctuation compensation parameter based on the bus voltage and to perform real-time compensation on the q-axis basic current to obtain a first q-axis current reference. An advance correction module is configured to predict the bus voltage of the next period and to perform advance correction on the first q-axis current reference to obtain a second q-axis current reference. A low-pass filtering module is configured to generate a field-weakening d-axis current reference based on the saturation state of the stator voltage and to perform low-pass filtering on the second q-axis current reference and the field-weakening d-axis current reference to obtain a dq-axis current instruction. A control updating module is configured to generate a PWM driving signal corresponding to the dq-axis current instruction and to control the inverter switch, and to collect a power deviation signal to update the q-axis basic current.

[0014] In the technical solution provided by the application, a dynamic current reference generation mechanism based on a bus voltage fluctuation compensation parameter is established, real-time adjustment of the current reference according to the voltage fluctuation is realized, and the problem of insufficient power control accuracy of the traditional fixed current reference method is overcome. A first-order prediction model based on the principle of capacitor charging and discharging and an adaptive gain adjustment strategy are used to realize accurate prediction of the bus voltage and advance correction of the current reference, and compared with the traditional lag compensation, the technical solution has a faster dynamic response. Through FFT spectrum analysis and an online learning algorithm, the double-frequency and four-frequency harmonic components are accurately compensated, and the output current harmonic content is effectively reduced. A simplified field-weakening control algorithm based on voltage margin is used to replace the traditional complex segmented control, and the running stability in the full-speed range is improved. The adaptive filtering processing technology is combined with the feedforward compensation mechanism to maintain good dynamic response while ensuring current smoothness. A multi-layer closed-loop control architecture from voltage detection to power feedback is constructed as a whole, and the power control accuracy, dynamic performance and running stability of the electrolytic capacitor-free permanent magnet synchronous motor driving system are significantly improved.

[0015] Other features and advantages of the present application will be set forth in the following specification, and in part will become apparent to those skilled in the art from the following specification, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0016] In order to make the above objectives, characteristics and advantages of the present application more apparent, clear and easy to understand, the following will describe in detail the preferred embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 An embodiment of the inverter power control method based on current given in the embodiments of the present application; Figure 2 An embodiment of the inverter power control system based on current given in the embodiments of the present application. DETAILED DESCRIPTION

[0018] In order to make the objectives, technical solutions and advantages of the embodiments of the present application more apparent, the following will describe the technical solutions of the present application in a clear and complete manner with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0019] The terms "comprise" and "have" and any variations thereof mentioned in the embodiments of the present application are intended to cover the inclusions without exclusivity. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but can optionally further comprise other steps or units not listed, or can optionally further comprise other steps or units inherent to the process, method, product or device.

[0020] In order to facilitate the understanding of the embodiments, first, a kind of inverter power control method based on current given disclosed in the embodiments of the present application will be introduced in detail. As shown in Figure 1 The inverter power control method based on current given includes the following steps: 101, based on bus voltage calculation fluctuation compensation parameter, and the q-axis basic current is compensated in real time, and the first q-axis current given is obtained; Specifically, the bus voltage is sampled in real time according to the switching frequency of the inverter, so as to ensure that the collected data covers the dynamic change characteristics of the voltage. A sliding window is set according to the fundamental period of the motor, and the moving average of the bus voltage is calculated through the sliding window to obtain the average value of the bus voltage. By comparing the sampling data with the average value, the fluctuation amplitude of the voltage is obtained, which is used to represent the change degree of the voltage relative to the average level. The frequency domain analysis is performed on the change component of the voltage signal, the main frequency component in the voltage fluctuation is extracted by using the fast Fourier transform method, and the harmonic components of the double frequency and the four times frequency are identified, and the amplitude is recorded to form the frequency spectrum data of the voltage fluctuation. The ratio of the voltage fluctuation amplitude to the average value of the bus voltage is used to determine the voltage fluctuation rate, which reflects the relative relationship between the voltage fluctuation and the average value. The voltage fluctuation rate and the frequency spectrum data are combined to obtain the fluctuation compensation parameter, and the fluctuation compensation parameter is input into the current compensation link to correct the q-axis basic current. In the updating process of the controller, the fluctuation compensation parameter is superimposed on the q-axis basic current reference value to obtain the first q-axis current given value. The first q-axis current given value is adjusted in real time in the value with the fluctuation of the bus voltage, so that the inverter can maintain the stability of the power output under the condition of the change of the bus voltage, and reduce the power deviation caused by the voltage disturbance.

[0021] 102. predicting the bus voltage of the next period and correcting the first q-axis current given value in advance to obtain a second q-axis current given value; Specifically, a current-power relationship model corresponding to the operating state of the motor is established. In the real-time calculation link of the controller, the bus charging current is calculated according to the current input power, and the grid input power is associated with the grid voltage and the power factor to obtain a current value that can represent the charging state of the bus. At the same time, the controller calculates the inverter output current according to the current dq-axis current given value and the motor speed, combined with the inverter modulation degree and the bus voltage level, to obtain the real-time current demand on the load side. By subtracting the bus charging current from the inverter output current, the bus current difference is obtained, which reflects the charge-discharge balance required by the bus capacitor in the current control period. The bus current difference is multiplied by the bus capacitance value to obtain a prediction of the voltage change. The prediction is superimposed on the current bus voltage to obtain the next cycle bus voltage prediction value. Real-time assessment of load disturbance is performed to detect the change rate of electromagnetic torque in the time dimension. By calculating the ratio between the instantaneous change speed of torque and the rated torque, a load change coefficient is obtained, which reflects the influence of load fluctuation on the dynamic performance of the system. In predictive control, the load change coefficient is used to modify the prediction gain of the controller, thereby forming an adaptive gain. When the load changes rapidly, the prediction gain is automatically increased to ensure the timeliness of the prediction correction action; when the load changes smoothly, the prediction gain is correspondingly reduced to avoid oscillation caused by excessive compensation. The next cycle bus voltage prediction value is compared with the target voltage reference value to calculate the prediction error, which represents the degree of deviation of the bus voltage from the expected level in the next cycle. The prediction error is weighted using the adaptive gain, and combined with the first q-axis current given value to obtain the corrected second q-axis current given value.

[0022] 103. generating a field weakening d-axis current given value based on the saturation state of the stator voltage, and low-pass filtering the second q-axis current given value and the field weakening d-axis current given value to obtain the dq-axis current instruction; Specifically, the actual amplitude of the stator voltage is obtained by square and square root operation based on the dq-axis voltage components. At the same time, the controller calculates the maximum output voltage limit that the inverter can provide according to the bus voltage, which is used to determine whether the motor operation is close to the saturation boundary. The difference between the maximum output voltage limit and the stator voltage is calculated, and the difference result is divided by the maximum output voltage limit to calculate the voltage margin. The voltage margin value represents the remaining space between the stator voltage and the available voltage. When the voltage margin is lower than the preset saturation judgment threshold, it is confirmed that the motor has entered the stator voltage saturation state, and the field weakening control strategy needs to be started. After detecting the saturation state, the difference between the stator voltage and the safe voltage boundary value is calculated, and it is used as the judgment basis of the voltage excess. When the difference is positive, it means that the stator voltage has exceeded the safe boundary, and the voltage excess is the positive value at this time; when the difference is negative or zero, it means that the stator voltage is still within the safe range, and the voltage excess is set to zero. The voltage excess is input into the field weakening control gain module, and through linear transformation relationship, it is converted into the corresponding field weakening d-axis current given value. The role of the field weakening current is to weaken the stator flux by introducing negative d-axis current, thereby reducing the demand of the motor for voltage and avoiding the system from continuing to fall into voltage saturation. The second q-axis current given value and the field weakening d-axis current given value are low-pass filtered to obtain the dq-axis current command, which is more smooth and stable in value, avoiding the impact of sudden changes and high-frequency components on the inverter switching devices and the motor operating state.

[0023] 104. Generate PWM drive signals corresponding to the dq-axis current commands and control the inverter switches, while collecting power deviation signals to update the q-axis basic current.

[0024] Specifically, the real-time feedback value of the dq-axis current is collected, and a current deviation is obtained by difference operation of the dq-axis current instruction. The current deviation is input into the current loop PI algorithm to perform proportional and integral operation, forming a dq-axis voltage control amount for driving the inverter. The dq-axis decoupling compensation voltage is calculated by combining the motor rotor position angle and the motor parameters, which is used to offset the cross influence related to inductance coupling and flux linkage. The decoupling compensation voltage and the voltage control amount are added to obtain the dq-axis voltage given for modulation. The voltage given is converted into a three-phase voltage instruction through inverse coordinate transformation, and the modulation unit determines the action time of the adjacent basic vector and the adjacent sector according to the three-phase voltage instruction. The space vector pulse width modulation is used to generate three-phase PWM duty cycle, and the on-off sequence and duration of the power switch tube are controlled accordingly to ensure that the modulation depth and the DC bus utilization rate are within a safe range. After the PWM drive signal is issued, the power calculation unit calculates the instantaneous output power with real-time voltage and current data as input, and obtains a power deviation signal by difference operation with the power reference value. The power deviation signal enters the power loop PI algorithm to generate a q-axis basic current regulation amount, which is superimposed and updated with the current q-axis basic current to form a new q-axis basic current. In order to suppress the high-frequency pulsation and sampling noise introduced by modulation, the controller configures amplitude limiting, slope limiting and anti-integral saturation processing in the discrete implementation of the current loop and the power loop, and considers dead-time compensation and minimum conduction time constraint in the SVPWM execution process, so as to maintain small deviation operation in the steady state interval, and maintain fast convergence and no obvious overshoot of electromagnetic response in dynamic working conditions, realizing the continuous control process of current tracking, decoupling compensation, space vector modulation and power closed loop collaborative work.

[0025] In a specific embodiment, the process of step 101 can specifically include the following steps: Collect the bus voltage according to the inverter switching frequency; Set a sliding window based on the fundamental period of the motor, and use the sliding window to calculate the moving average of the bus voltage to obtain the average value of the bus voltage and calculate the voltage fluctuation amplitude synchronously; Extract the fluctuation component in the bus voltage and identify the harmonic component strength of the double-frequency and four-frequency, to obtain the voltage fluctuation frequency spectrum data; Determine the voltage fluctuation rate using the ratio of the voltage fluctuation amplitude to the average value of the bus voltage, and generate the fluctuation compensation parameter combining the voltage fluctuation rate and the voltage fluctuation frequency spectrum data; Use the fluctuation compensation parameter to compensate the q-axis basic current in real time to obtain the first q-axis current given.

[0026] Specifically, the bus voltage sampling frequency is set to the same level as the inverter switching frequency, so that the instantaneous value of the voltage is obtained every switching cycle, thereby comprehensively covering the fluctuation characteristics of the voltage in the time domain. The voltage sampling data is continuously input into the calculation module of the controller, and a sliding window based on the fundamental period of the motor is established in the control algorithm. The moving average calculation is performed on the sampled voltage data through the sliding window, thereby effectively filtering out high-frequency interference and obtaining the average value of the bus voltage. The difference between the sampling value and the moving average value is used as the voltage fluctuation amplitude to represent the size of the voltage instantaneous change. The voltage fluctuation component is input into the frequency spectrum analysis module, and the fast Fourier transform is used to perform frequency domain decomposition on the voltage fluctuation component to obtain the amplitude data corresponding to each frequency point. In the analysis results, the second harmonic and the fourth harmonic components are identified, which are derived from the motor electrical angle frequency and its high-order components, and are the main factors causing current fluctuation and power pulsation. By extracting and determining the amplitude of the second harmonic and the fourth harmonic, the frequency spectrum data of the bus voltage is formed, and the characteristics of the voltage fluctuation in the frequency domain are described. The voltage fluctuation rate is obtained by ratio operation of the voltage fluctuation amplitude and the average value of the bus voltage, which reflects the relative size of the voltage fluctuation relative to the average level, and is used as a quantitative index of system operation stability. If the voltage fluctuation rate is high, it means that the proportion of voltage transient change is obvious, which will interfere with the current instruction tracking, so a larger correction amplitude needs to be given in the compensation calculation. The calculation result of the voltage fluctuation rate is fused with the frequency spectrum data to form the fluctuation compensation parameter. The fluctuation compensation parameter is input into the current given correction module to compensate the q-axis basic current in real time. The controller superimposes the basic current reference value and the compensation parameter in the calculation process, so that the q-axis current reference value can be adjusted in real time with the fluctuation of the bus voltage, and the first q-axis current given is generated. The first q-axis current given is updated according to the real-time state of the voltage, and its value is corrected with the change of the voltage fluctuation in amplitude and harmonic characteristics. Through real-time updating, the current control of the inverter can follow the dynamic change of the bus voltage, avoid the power deviation caused by voltage deviation or harmonic disturbance, and improve the power control accuracy of the system under the condition of fast fluctuation and complex load.

[0027] In a specific embodiment, the process of performing real-time compensation on the q-axis basic current by using the fluctuation compensation parameter to obtain the first q-axis current given can specifically include the following steps: The main compensation term and the harmonic compensation term are constructed based on the fluctuation compensation parameter, the main compensation term is modulated according to the square sine function of the motor rotor electrical angle and the bus voltage fluctuation rate, and the harmonic compensation term is modulated according to the second harmonic sine function of the motor fundamental. The product of the motor electrical angle frequency and the bus capacitance value and the bus voltage nominal value is divided by the average output power, and then multiplied by a coefficient of 0.5 to obtain a main compensation coefficient. The main compensation coefficient is multiplied by the main compensation term to obtain a main compensation current component. a deviation power value of the actual output power and the power reference value is calculated, and a harmonic compensation coefficient is updated according to the deviation power value, to obtain an updated harmonic compensation coefficient; the updated harmonic compensation coefficient is multiplied by the harmonic compensation term to obtain a harmonic compensation current component; the q-axis basic current, the main compensation current component and the harmonic compensation current component are superimposed to obtain a first q-axis current given value.

[0028] Specifically, a current modulation model is established, dynamic fluctuation information of the bus voltage is mapped to a q-axis current correction signal, and the compensation effect is refined into two components: on the one hand, it is used to offset the slow change trend of the overall amplitude of the bus voltage, and on the other hand, it is used to correct the high-frequency disturbance caused by voltage harmonics in real time. In the current modulation model, the main compensation term is used to respond to low-frequency fluctuations, and the construction method is to use the square sine function of the motor rotor electric angle as the fundamental wave modulation factor, and multiply it with the bus voltage fluctuation rate to form an amplitude modulation result that changes with the periodic rotation state of the rotor. The main compensation term can simulate the influence of bus voltage fluctuation on the main power component of the motor, so that the current given value has dynamic adjustment capability related to the rotor position. At the same time, the harmonic compensation term adopts a double-frequency sine function based on the electric angle frequency as the modulation factor to match the double-frequency disturbance mode in the bus voltage, and to align the compensation with the main harmonic component in the frequency domain, thereby forming a targeted suppression of high-frequency disturbance. In the construction process of the main compensation current component, the main compensation coefficient is calculated according to the bus capacitance value, the motor electric angle frequency and the average output power in the current control period. The physical meaning of the main compensation coefficient lies in representing the sensitivity and required response depth of the system to bus voltage disturbance, and it has load correlation and operating state correlation. The main compensation coefficient is calculated in real time through a preset model to ensure that the compensation strength is in a reasonable proportion to the power level. The main compensation coefficient is multiplied by the main compensation term to obtain the main compensation current component. The output power at the current time is calculated, and the deviation power value is obtained by subtracting the reference power value from the actual output power, which reflects the error degree between the current control result and the target power. According to the deviation power value, the original harmonic compensation coefficient is modified by using an incremental adjustment strategy, and the updated harmonic compensation coefficient is obtained by weighting the error term based on the original coefficient and combining the harmonic modulation mode of the current rotor angle. The updated coefficient can adaptively change with the actual power error of the system to enhance the closed-loop performance of the compensation. The updated harmonic compensation coefficient is multiplied by the harmonic compensation term to generate the harmonic compensation current component. The harmonic compensation current component mainly compensates for the part of the q-axis current affected by high-frequency harmonic modulation, so that the current reference value can maintain an amplitude structure consistent with the target output in the frequency domain. The main compensation current component and the harmonic compensation current component are superimposed by addition with the q-axis basic current to obtain the first q-axis current given value.

[0029] In a specific embodiment, the process of performing step 102 can specifically include the following steps: Calculate bus charging current according to current input power, and calculate inverter output current according to dq-axis current given value and current rotating speed; Subtract bus charging current from inverter output current to obtain bus current difference; Multiply bus current difference by bus capacitance value to obtain a ratio, multiply the ratio by control period to obtain a calculation result, and superimpose the calculation result on bus voltage to obtain next period bus voltage; Detect time rate of change of electromagnetic torque to obtain torque rate of change, calculate load change coefficient according to ratio of torque rate of change to rated torque, and adjust prediction control gain based on load change coefficient to obtain adaptive gain; Generate prediction deviation according to next period bus voltage, and calculate second q-axis current given value according to prediction deviation and first q-axis current given value using adaptive gain.

[0030] Specifically, the controller collects input power data in real time, and divides the input power by the instantaneous value of the bus voltage to obtain the bus charging current, which represents the energy inflow from the power grid or DC power supply to the bus capacitor. At the same time, according to the dq-axis current given value of the motor operation and the current speed, the output current of the inverter is calculated through the mathematical model of the motor, reflecting the power transmission from the inverter to the motor side. Subtract the bus charging current from the inverter output current to obtain the bus current difference, which describes the net charging and discharging current that the bus capacitor needs to bear in the current period. Perform a ratio operation on the bus current difference and the bus capacitance value, and then multiply it by the control period to obtain a calculation result for predicting the voltage change, which represents the change amplitude of the voltage across the capacitor due to the net current inflow or outflow in a control period. Add the voltage change directly to the current bus voltage to obtain the predicted value of the bus voltage in the next period. The control system introduces a dynamic adjustment mechanism for load change factors. The controller obtains the instantaneous value of the time rate of change of electromagnetic torque by monitoring the time rate of change of electromagnetic torque in real time, and performs a ratio calculation on the torque rate of change and the rated torque to obtain a load change coefficient, which reflects the deviation between the current motor load and the rated operating conditions. The more intense the load fluctuation, the larger the coefficient value. In the predictive control strategy, the load change coefficient is used to modify the gain of the controller, thereby forming an adaptive gain. When a rapid load change is detected, the gain of the predictive control is correspondingly increased to ensure that the correction action can keep up with the rapid changes in voltage and current; while in the case of stable load, the adaptive gain is reduced to reduce the risk of oscillation caused by excessive compensation. Through adaptive adjustment, good stability and response speed are maintained under different load conditions. Compare the predicted voltage with the expected reference voltage to calculate the prediction error. The prediction error represents the degree to which the bus voltage deviates from the ideal reference value. Combine the prediction error with the adaptive gain to form the correction amount of the first q-axis current given value. The prediction error is amplified or reduced by the adaptive gain, and then operated with the first q-axis current given value to obtain the second q-axis current given value.

[0031] In a specific embodiment, the process of generating a prediction error according to the bus voltage of the next period and calculating a second q-axis current given value according to the prediction error and a first q-axis current given value using an adaptive gain can specifically include the following steps: The difference between the bus voltage of the next period and the bus voltage reference value is taken as the prediction error; The prediction error is multiplied by the adaptive gain to obtain a target deviation value, and the target deviation value is multiplied by the q-axis current rated value to obtain a q-axis current correction amount; The q-axis current correction amount is algebraically added to the first q-axis current given value to obtain the second q-axis current given value.

[0032] Specifically, the bus voltage prediction result of the next cycle is read, and the bus voltage reference value is read from the power target management module. The bus voltage prediction result and the bus voltage reference value are respectively subjected to denoising and quantization processing, and discrete low-pass filtering and uniform scaling coefficient are used to avoid amplitude distortion and phase mismatch caused by different numerical paths. The difference between the two is calculated after time alignment at the same sampling time, and the difference is defined as the prediction deviation. The prediction deviation is multiplied by the adaptive gain, which is derived from the real-time conversion result of the load change evaluation unit to the ratio of the electromagnetic torque change rate to the rated torque, and is smoothed and updated according to the amplitude limit and slope constraint in each control cycle, which is used to improve the correction strength in fast load disturbance and to suppress excessive amplification in stable working conditions. The controller multiplies the prediction deviation and the adaptive gain to obtain the target deviation value, which is then multiplied by the q-axis current rated value and subjected to unit consistency check and symbol inheritance rule to form the q-axis current correction amount. In order to avoid electromagnetic shock caused by current reference jump, the q-axis current correction amount enters two levels of constraints: the first level is amplitude limiting, which sets the upper and lower limits according to a certain proportion of the rated current to ensure that the correction amount does not exceed the allowable working boundary of the inverter and the motor; the second level is the change rate limit, which is linearly limited according to the control period and the allowed rising / falling slope to ensure the continuity and derivability of the reference trajectory. The q-axis current correction amount after constraint is subjected to algebraic addition operation with the first q-axis current given at the same sampling time, and the calculation sequence adopts the write-back strategy of correcting first and saving later to avoid race conditions caused by concurrent tasks to shared buffers; the addition result is output as the second q-axis current given, which is subjected to consistency check by anti-integration saturation logic and field coupling constraint before being written back. If a conflict with the d-axis field limiting value, the maximum power angle limit or the overcurrent protection threshold is detected, the q-axis current correction amount is rolled back and trimmed according to the priority table to ensure consistency with the global safety strategy.

[0033] In a specific embodiment, the process of performing step 103 can specifically include the following steps: Based on the dq-axis voltage components, the stator voltage is calculated by square sum and square root operation, and the maximum output voltage limit is calculated based on the bus voltage; After the difference between the maximum output voltage limit and the stator voltage is calculated and then divided by the maximum output voltage limit, the voltage margin is obtained, and when the voltage margin is lower than the saturation judgment threshold, the stator voltage saturation state is confirmed; If saturated, the voltage difference between the stator voltage and the safe voltage boundary value is calculated, and when the voltage difference is positive, the voltage excess is determined, and when the voltage difference is negative or zero, the voltage excess is set to zero; The voltage excess is input into the field control gain for linear transformation, and the field d-axis current given is output; The second q-axis current given and the field d-axis current given are subjected to low-pass filtering to obtain the dq-axis current command.

[0034] Specifically, the d-axis voltage component and the q-axis voltage component are squared respectively, and the results are added together, and then the amplitude of the stator voltage is obtained by square root operation. The stator voltage value represents the voltage support required by the motor stator under the current operating condition. At the same time, the controller calculates the maximum output voltage limit that the inverter can provide according to the DC bus voltage, and the maximum output voltage limit is equal to the bus voltage divided by the square root of three and is modified by the modulation method and the dead time, representing the voltage capability boundary of the inverter under the current power supply condition. Subtract the maximum output voltage limit from the stator voltage and divide the difference by the maximum output voltage limit to obtain a dimensionless ratio, i.e. the voltage margin. The voltage margin can reflect the remaining space of the current stator voltage relative to the output voltage limit of the inverter. When the voltage margin is greater than the preset threshold, it indicates that the system is still in the safe interval, and when the voltage margin is lower than the saturation judgment threshold, it is confirmed that the inverter enters the stator voltage saturation state, and the field weakening control strategy needs to be started. After determining that it enters the saturation state, the difference between the stator voltage and the safe voltage boundary value is calculated to determine the degree of voltage overrun. The safe voltage boundary value is set as a fixed proportional coefficient of the maximum output voltage limit to ensure a safety margin during operation. If the stator voltage is greater than the safe voltage boundary value, the difference is positive, and the positive value is defined as the voltage overrun; if the difference is zero or negative, it means that the stator voltage has not exceeded the safe boundary, and the voltage overrun is set to zero at this time. The voltage overrun is input into the field weakening control gain link for linear transformation. The field weakening control gain, as a proportional coefficient, directly maps the voltage overrun to the negative current required to be applied in the d-axis direction to generate the field weakening d-axis current reference. The function of the field weakening current is to offset a part of the flux generated by the permanent magnet, reduce the voltage required by the motor stator, and thus relieve voltage saturation. Through linear transformation, the field weakening current is proportional to the voltage overrun, so that the field weakening compensation can not only remain stable when the voltage overrun is small, but also increase the compensation depth quickly when the voltage overrun is serious. The second q-axis current reference and the field weakening d-axis current reference are input into a low-pass filter module to obtain the dq-axis current command. By setting an appropriate cutoff frequency, the low-pass filter effectively eliminates high-frequency fluctuations caused by sampling noise, rapid switching and transient disturbances, while retaining the main dynamic trends of the signal. During the filtering process, the second q-axis current reference can maintain the stability of the output power, while the field weakening d-axis current reference can be gradually applied to avoid electromagnetic shocks to the motor and inverter caused by sudden changes in the current reference.

[0035] In a specific embodiment, the process of inputting the voltage overrun into the field weakening control gain for linear transformation and outputting the field weakening d-axis current reference can specifically include the following steps: The voltage overrun is input as an input signal into a linear transformer, multiplied by the field weakening control gain for proportional amplification to obtain the field weakening current amplitude; The maximum allowable power angle corresponding to the flux-weakening current upper limit value is calculated according to the second q-axis current given value, and the effective flux-weakening current amplitude is selected according to the flux-weakening current amplitude and the flux-weakening current upper limit value. The mathematical sign transformation is performed on the effective flux-weakening current amplitude, and the positive value is converted into a corresponding negative value to obtain the flux-weakening current value, and the flux-weakening current value is output as the flux-weakening d-axis current given value.

[0036] Specifically, the voltage excess is taken as an input signal to a linear transformer, and the linear transformer performs calculation according to proportional operation logic inside and multiplies a preset flux-weakening control gain to complete proportional amplification. The value of the flux-weakening control gain is determined according to motor parameters and inverter voltage capacity in the design stage, and reflects the size of the required compensation current corresponding to the unit voltage excess. Through proportional amplification operation, the output quantity obtained is the preliminary calculated flux-weakening current amplitude, which reflects the degree of flux-weakening compensation required to be applied on the d-axis in order to maintain normal operation of the motor and the inverter under the current voltage deviation. The flux-weakening current cannot be increased indefinitely, otherwise it will affect the torque capacity of the motor. After the flux-weakening current amplitude is calculated, a constraint condition is introduced. The maximum allowable power angle is calculated according to the second q-axis current given value, and the upper limit value of the flux-weakening current is derived based on this. The power angle is defined as the phase angle between the motor voltage and current, and an excessively large power angle will cause the motor to operate close to instability, so it is necessary to ensure that the compensation amount of the flux-weakening current will not cause the power angle to exceed the allowable range. Through joint calculation of the second q-axis current given value and the motor inductance parameters, the upper limit value of the flux-weakening current corresponding to the maximum allowable power angle is obtained. Based on the flux-weakening current amplitude and the flux-weakening current upper limit value, the effective value is selected. When the flux-weakening current amplitude is less than or equal to the upper limit value, it indicates that the compensation amount does not exceed the allowable range, and at this time the flux-weakening current amplitude is directly taken as the effective flux-weakening current amplitude; when the flux-weakening current amplitude is greater than the upper limit value, it indicates that the compensation will cause excessive flux-weakening, thereby reducing the torque capacity of the system or affecting the operation stability, and at this time the effective flux-weakening current amplitude is limited to the upper limit value, so as to ensure that the compensation is carried out within the safety boundary. The mathematical sign transformation is performed on the effective flux-weakening current amplitude. Because the essence of flux-weakening control is to apply a part of negative current in the d-axis direction to offset the excessively high voltage demand caused by the permanent magnet flux linkage, therefore any positive value of the flux-weakening current amplitude must be converted into a corresponding negative value through mathematical sign transformation, so as to meet the physical meaning of the flux-weakening current. The controller completes this process through sign inversion operation when implemented, and the effective flux-weakening current amplitude is multiplied by -1 to obtain the final flux-weakening current value. The flux-weakening current value is negative in value and represents the directionality characteristic of offsetting the flux linkage in meaning. The flux-weakening current value after sign transformation is output as the flux-weakening d-axis current given value and is directly input into the current loop control module to form the dq-axis current instruction with the q-axis current reference value.

[0037] In a specific embodiment, the process of performing low-pass filtering on the second q-axis current command and the field-weakening d-axis current command to obtain the dq-axis current command can specifically include the following steps: detecting a q-axis current change rate of the second q-axis current command and a d-axis current change rate of the field-weakening d-axis current command; performing slope limiting processing when the q-axis current change rate exceeds a first preset limit value or the d-axis current change rate exceeds a second preset limit value to obtain the dq-axis current command; judging the operating state according to the power change rate, calculating the target cutoff frequency as a first cutoff frequency in steady-state operation, and calculating the target cutoff frequency as a second cutoff frequency in dynamic operation, the first cutoff frequency being lower than the second cutoff frequency; inputting the dq-axis current command into a first-order low-pass filter for filtering processing to obtain a filtered dq-axis current signal, the cutoff frequency of the first-order low-pass filter being set as the target cutoff frequency; calculating a time derivative of the dq-axis current command, multiplying the time derivative by a filter time constant to generate a feedforward compensation signal, and superimposing the feedforward compensation signal on the filtered dq-axis current signal to obtain the dq-axis current command.

[0038] Specifically, the continuous change process of the second q-axis current given and the field-weakening d-axis current given is monitored, and the rate of change thereof is calculated by the numerical difference in two adjacent control periods. The current rate of change reflects the time derivative characteristic of the current reference signal, and is an important basis for measuring the smoothness and dynamic mutation risk of the current trajectory. When the rate of change of the q-axis current is detected to exceed a first preset limit value, or the rate of change of the d-axis current exceeds a second preset limit value, a slope limiting mechanism is triggered, the maximum change amplitude of the current increment in each period is forcibly limited, the current trajectory is kept in a continuous and slow change range, and problems such as voltage peak, current impact or modulation instability of the inverter power device caused by too fast change are avoided. The dq-axis current given signal is obtained after the limiting process. The target filtering characteristic is set according to the operating state. The judgment basis of the operating state is the current power output change speed. When the power change rate is lower than the set threshold in the continuous period, it is determined that the state is stable, a lower cut-off frequency is selected for filtering processing, the signal stability is strengthened, and the residual high-frequency noise or electromagnetic disturbance in the current reference is reduced; and when the power change rate exceeds the threshold, it is determined that the state is dynamic, a higher cut-off frequency is selected, and sufficient signal bandwidth is reserved, so that the current reference can respond to external disturbance or load mutation in time. On this basis, the target cut-off frequency is determined and the corresponding parameters are configured, a first-order low-pass filter is constructed, and the dq-axis current given after limiting is processed. In the filtering process, the dq-axis current given after limiting is input into the low-pass filter for real-time operation, so that the output signal retains the original dynamic trend while removing high-frequency fluctuations, and a smooth current trajectory with response capability is obtained. Considering the inherent delay effect of the low-pass filtering process, a feedforward compensation mechanism is introduced to improve the dynamic performance of the overall control chain. The time change rate of the dq-axis current given is calculated, and a signal for feedforward compensation is generated according to the previously set filtering parameters. The compensation signal can provide an advance response when the current changes rapidly, and offset the control lag problem caused by filtering. The feedforward compensation signal is superimposed on the filtered dq-axis current signal to form the dq-axis current command.

[0039] In a specific embodiment, the process of step 104 can specifically include the following steps: The dq-axis current feedback value and the dq-axis current command are subjected to deviation operation to obtain a current deviation, and the current deviation is input into a PI controller for proportional and integral operation to obtain a dq-axis voltage control quantity; The dq-axis decoupling compensation voltage is calculated according to the motor rotor position angle and motor parameters, and the dq-axis decoupling compensation voltage and the dq-axis voltage control quantity are subjected to addition operation to obtain a dq-axis voltage given; The dq-axis voltage given is converted into a three-phase voltage command through coordinate transformation, and the sector position and action time are calculated by using the SVPWM modulation algorithm to generate a PWM drive signal for controlling the on-off of the inverter power switch tube. The instantaneous output power is calculated, and a power deviation signal is obtained by subtracting the power reference value from the instantaneous output power; the power deviation signal is processed by a power loop PI controller to obtain a q-axis basic current regulation amount and update the q-axis basic current.

[0040] Specifically, the dq-axis current command is taken as the target current value of the current control period, and is compared with the actual dq-axis current feedback value collected cycle by cycle. The current deviation at the current time is calculated by subtracting the feedback value from the high-speed sampling channel from the current command, reflecting the instantaneous error state of the current control loop in the current control period, and is the direct input quantity for executing closed-loop regulation. The controller sends the current deviation as an input signal to the proportional-integral controller of the current loop, forms a response term proportional to the error in the proportional regulation channel to provide fast dynamic compensation capability, and accumulates the current error in the integral channel to eliminate steady-state deviation and improve steady-state control accuracy. The proportional and integral results are combined to form the voltage control quantity in the dq-axis direction, representing the control voltage required to drive the motor current to quickly approach the target command under the current error state. To improve the accuracy of current regulation and reduce the cross-coupling interference between dq-axes, the decoupling compensation voltage in the dq-axis direction is calculated based on the known motor parameters and motor rotor position angle. The decoupling compensation voltage is used to offset the cross-interference components caused by inductance coupling, flux linkage change and electrical angular velocity. In this process, the controller calculates the additional voltage introduced in the d-axis due to the q-axis change and the cross voltage introduced in the q-axis due to the interaction of the d-axis and the flux linkage according to the current electrical angular velocity, permanent magnet flux linkage parameters and d-axis and q-axis current values. After performing addition operation on the calculated dq-axis decoupling compensation voltage and the dq-axis voltage control quantity output by the current error PI controller, the dq-axis voltage given value is generated. The dq-axis voltage given value is input into the coordinate transformation module for transformation from the rotating coordinate system to the stationary three-phase coordinate system, i.e. completing the conversion process from the dq coordinate system to the three-phase abc coordinate system. The conversion process relies on the current electrical angle information and maps the two-dimensional voltage vector into three-phase voltage commands through the sine and cosine projection of the voltage given value in the electrical angle space. After obtaining the three-phase voltage commands, the controller enters the modulation stage and uses the space vector pulse width modulation algorithm to modulate the target three-phase voltage vector. In the modulation process, the controller determines which part of the six sectors the current three-phase voltage vector is located in, and then calculates the action time corresponding to each sector according to the modulation depth and the distribution of the voltage vector, and further synthesizes the PWM control waveform required by the target voltage vector. After completing the modulation calculation, three-phase PWM drive signals are generated according to the calculated action time, which are input into the power switch control interface of the inverter to control the on-off sequence and duration of the power devices, and output the corresponding voltage modulation waveform. While the inverter executes PWM drive and completes voltage output, the dq-axis voltage and current feedback values at the output end are collected in real time, and the instantaneous output power is calculated according to the motor static energy model. The output power is compared with the power reference value of the system to obtain the power deviation signal of the current period.The power deviation signal is input into a power loop PI controller as an outer loop feedback signal for adjustment processing, in which an immediate response to the current power deviation is formed in a proportional adjustment channel, and a correction mechanism for accumulated errors is established in an integral channel. The PI controller output is analyzed into a q-axis basic current adjustment amount, and is used to update the current q-axis basic current value. The q-axis basic current value will serve as a starting reference point for generating the first q-axis current in the next control cycle, thereby completing the closed-loop coupling between the entire power control and current control.

[0041] The above describes the inverter power control method based on current given in the embodiment of the application, and the inverter power control system based on current given in the embodiment of the application is described below. Referring to Figure 2 The inverter power control system based on current given in the embodiment of the application includes one embodiment: The real-time compensation module 201 is configured to calculate fluctuation compensation parameters based on the bus voltage, and to perform real-time compensation on the q-axis basic current to obtain the first q-axis current given value. The advance correction module 202 is configured to predict the bus voltage in the next cycle and to perform advance correction on the first q-axis current given value to obtain the second q-axis current given value. The low-pass filter module 203 is configured to generate a field-weakening d-axis current given value based on the stator voltage saturation state, and to perform low-pass filtering on the second q-axis current given value and the field-weakening d-axis current given value to obtain the dq-axis current instruction. The control update module 204 is configured to generate a PWM drive signal corresponding to the dq-axis current instruction and to control the inverter switch, while collecting the power deviation signal to update the q-axis basic current.

[0042] Through the cooperation of the above-mentioned components, through the establishment of a q-axis current given generation mechanism based on bus voltage fluctuation compensation parameters, the current given is adjusted in real time with the bus voltage fluctuation, the power control accuracy problem of the traditional fixed current given method in the voltage fluctuation environment is overcome, and the power tracking performance of the electrolytic capacitor-free system is significantly improved. A first-order prediction model based on the principle of capacitor charging and discharging and an adaptive gain adjustment strategy are used to realize accurate prediction of the bus voltage in the next control period and advance correction of the current given, which has faster dynamic response speed and higher control accuracy than the traditional lag compensation method. Through FFT spectrum analysis to identify the second and fourth harmonic components in the bus voltage, and combining the online learning algorithm to adaptively adjust the harmonic compensation coefficient, accurate compensation of the voltage fluctuation harmonic is realized, the harmonic content of the output current is effectively reduced, and the electromagnetic compatibility of the system is improved. A weak magnetic judgment mechanism based on the stator voltage vector amplitude and voltage margin is established, a linear weak magnetic control algorithm is used to replace the traditional complex segmented control, while ensuring the voltage saturation protection at high speed, and the running stability in the full speed range is improved. A low-pass filter with a change rate limit and an adaptive cutoff frequency adjustment is designed, combined with a feedforward compensation mechanism to reduce filtering delay, while maintaining good dynamic response capability while ensuring current given smoothness, avoiding system oscillation caused by current mutation, realizing high-precision power control, and having stronger robustness and adaptability than existing open-loop or single closed-loop control methods.

[0043] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, system and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0044] The integrated unit, if realized in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various program code storage media.

[0045] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalent replacements; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for inverter power control based on current given, characterized by, The application relates to a method for generating q-axis current given value of inverter, comprising the following steps: calculating fluctuation compensation parameter based on bus voltage and compensating q-axis basic current in real time to obtain first q-axis current given value; predicting bus voltage of next period and correcting the first q-axis current given value in advance to obtain second q-axis current given value; generating weak magnetic d-axis current given value based on stator voltage saturation state and low-pass filtering the second q-axis current given value and the weak magnetic d-axis current given value to obtain dq-axis current instruction; generating PWM driving signal corresponding to the dq-axis current instruction and controlling inverter switch, and collecting power deviation signal to update the q-axis basic current.

2. The current command-based inverter power control method of claim 1, wherein, The application relates to a method for generating q-axis current given value of inverter, comprising the following steps: collecting bus voltage according to inverter switch frequency; setting sliding window based on motor fundamental wave period and calculating moving average of the bus voltage by using the sliding window to obtain bus voltage average value and calculate voltage fluctuation amplitude synchronously; extracting fluctuation component in the bus voltage and identifying harmonic component strength of double frequency and four times frequency to obtain voltage fluctuation frequency spectrum data; determining voltage fluctuation rate by using the ratio of the voltage fluctuation amplitude to the bus voltage average value and generating fluctuation compensation parameter by combining the voltage fluctuation rate and the voltage fluctuation frequency spectrum data; compensating q-axis basic current in real time by using the fluctuation compensation parameter to obtain first q-axis current given value.

3. The current reference based inverter power control method of claim 2, wherein, The application relates to a method for generating q-axis current given value of inverter, comprising the following steps: constructing main compensation term and harmonic compensation term based on the fluctuation compensation parameter, the main compensation term is modulated according to square sine function of motor rotor electric angle and bus voltage fluctuation rate, and the harmonic compensation term is modulated according to motor fundamental wave double frequency sine function; dividing the product of the motor electric angle frequency, the bus capacitance value and the bus voltage nominal value by the average output power, multiplying the result by a coefficient of 0.5 to obtain main compensation coefficient, multiplying the main compensation coefficient by the main compensation term to obtain main compensation current component; calculating deviation power value of actual output power and power reference value and updating harmonic compensation coefficient according to the deviation power value to obtain updated harmonic compensation coefficient; multiplying the updated harmonic compensation coefficient by the harmonic compensation term to obtain harmonic compensation current component; superimposing q-axis basic current, the main compensation current component and the harmonic compensation current component to obtain first q-axis current given value.

4. The current command-based inverter power control method of claim 1, wherein, The application relates to a method for generating q-axis current given value of inverter, comprising the following steps: calculating bus charging current according to current input power, calculating inverter output current according to dq-axis current given value and current rotating speed at the same time; subtracting the bus charging current from the inverter output current to obtain bus current difference value; multiplying the ratio of the bus current difference value to bus capacitance value by control period to obtain calculation result, and superimposing the calculation result on the bus voltage to obtain bus voltage of next period. Detecting a time change rate of an electromagnetic torque to obtain a torque change rate, calculating a load change coefficient according to a ratio of the torque change rate to a rated torque, and adjusting a predictive control gain based on the load change coefficient to obtain an adaptive gain; Generating a prediction deviation according to a bus voltage of a next cycle, and calculating a second q-axis current given value according to the prediction deviation and the first q-axis current given value by using the adaptive gain.

5. The current reference based inverter power control method of claim 4, wherein, The generating a prediction deviation according to a bus voltage of a next cycle, and calculating a second q-axis current given value according to the prediction deviation and the first q-axis current given value by using the adaptive gain comprises: Taking a difference between the bus voltage of the next cycle and a bus voltage reference value as the prediction deviation; Multiplying the prediction deviation by the adaptive gain to obtain a target deviation value, and multiplying the target deviation value by a q-axis current rated value to obtain a q-axis current correction amount; Performing an algebraic addition operation on the q-axis current correction amount and the first q-axis current given value to obtain the second q-axis current given value.

6. The current command-based inverter power control method of claim 1, wherein, The generating a field-weakening d-axis current given value based on a stator voltage saturation state, and performing a low-pass filtering operation on the second q-axis current given value and the field-weakening d-axis current given value to obtain a dq-axis current instruction comprises: Calculating a stator voltage based on a square sum and square root operation on dq-axis voltage components, and calculating a maximum output voltage limit value according to a bus voltage; Performing a difference operation on the maximum output voltage limit value and the stator voltage, and dividing a result of the difference operation by the maximum output voltage limit value to obtain a voltage margin, and confirming the stator voltage saturation state when the voltage margin is lower than a saturation judgment threshold value; If the stator voltage is saturated, calculating a voltage difference value between the stator voltage and a safe voltage boundary value, and determining a voltage excess amount as positive when the voltage difference value is positive, and setting the voltage excess amount as zero when the voltage difference value is negative or zero; Inputting the voltage excess amount into a field-weakening control gain to perform a linear transformation, and outputting a field-weakening d-axis current given value; Performing a low-pass filtering operation on the second q-axis current given value and the field-weakening d-axis current given value to obtain the dq-axis current instruction.

7. The current reference based inverter power control method of claim 6, wherein, The inputting the voltage excess amount into a field-weakening control gain to perform a linear transformation, and outputting a field-weakening d-axis current given value comprises: Inputting the voltage excess amount as an input signal into a linear transformer, multiplying the voltage excess amount by a field-weakening control gain to perform a proportional amplification, and obtaining a field-weakening current amplitude value; Calculating a maximum allowable power angle corresponding to an upper limit value of a field-weakening current according to the second q-axis current given value, and selecting an effective field-weakening current amplitude value according to the field-weakening current amplitude value and the upper limit value of the field-weakening current; Performing a mathematical sign transformation on the effective field-weakening current amplitude value to convert a positive number value into a corresponding negative number value, obtaining a field-weakening current numerical value, and outputting the field-weakening current numerical value as the field-weakening d-axis current given value.

8. The current reference based inverter power control method of claim 7, wherein, The performing a low-pass filtering operation on the second q-axis current given value and the field-weakening d-axis current given value to obtain the dq-axis current instruction comprises: Detecting a q-axis current change rate of the second q-axis current given value and a d-axis current change rate of the field-weakening d-axis current given value; Performing a slope limiting process when the q-axis current change rate exceeds a first preset limit value or the d-axis current change rate exceeds a second preset limit value, and obtaining the dq-axis current instruction; According to the power change rate to determine the operation state, the target cut-off frequency is calculated as a first cut-off frequency in the steady state operation, and the target cut-off frequency is calculated as a second cut-off frequency in the dynamic operation, and the first cut-off frequency is lower than the second cut-off frequency; The given dq-axis current is filtered by a first-order low-pass filter to obtain a filtered dq-axis current signal, and the cut-off frequency of the first-order low-pass filter is set as the target cut-off frequency; The time derivative of the given dq-axis current is calculated, the time derivative is multiplied by a filter time constant to generate a feedforward compensation signal, and the feedforward compensation signal is superimposed on the filtered dq-axis current signal to obtain a dq-axis current instruction.

9. The current reference based inverter power control method of claim 1, wherein, The generation of the PWM driving signal corresponding to the dq-axis current instruction and the control of the inverter switch are simultaneously performed, and the power deviation signal is collected to update the q-axis basic current, including: The deviation operation is performed on the dq-axis current feedback value and the dq-axis current instruction to obtain a current deviation, and the current deviation is input into a PI controller to perform proportional and integral operations to obtain a dq-axis voltage control amount; The dq-axis decoupling compensation voltage is calculated according to the motor rotor position angle and the motor parameters, and the addition operation is performed on the dq-axis decoupling compensation voltage and the dq-axis voltage control amount to obtain a dq-axis voltage given value; The dq-axis voltage given value is converted into a three-phase voltage instruction through coordinate transformation, the sector position and the action time are calculated by using the SVPWM modulation algorithm, and the PWM driving signal is generated to control the on-off of the inverter power switch tube. The instantaneous output power is calculated, the power deviation signal is obtained by subtracting the power reference value from the instantaneous output power, and the power loop PI controller is used to process the power deviation signal to obtain the q-axis basic current adjustment amount and update the q-axis basic current.

10. An inverter power control system based on current given, characterized by, The current-given-based inverter power control method is used to perform the method according to any one of claims 1-9, including: A real-time compensation module is configured to calculate fluctuation compensation parameters based on bus voltage and to perform real-time compensation on the q-axis basic current to obtain a first q-axis current given value; An advance correction module is configured to predict the bus voltage of the next period and to perform advance correction on the first q-axis current given value to obtain a second q-axis current given value; A low-pass filtering module is configured to generate a field-weakening d-axis current given value based on the saturation state of the stator voltage and to perform low-pass filtering on the second q-axis current given value and the field-weakening d-axis current given value to obtain a dq-axis current instruction; A control updating module is configured to generate a PWM driving signal corresponding to the dq-axis current instruction and to control the inverter switch, and to collect a power deviation signal to update the q-axis basic current.

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