A power supply device and a control method with adjustable output voltage

Abstract

The application provides a power supply device and a control method with adjustable output voltage, the power supply device comprising: a front-stage three-level AC / DC structure input side receiving a wide voltage range of three-phase alternating current; a rear-stage isolation type three-level DC / DC structure output side connected with a load end through a DC bus; wherein the front-stage three-level AC / DC structure is connected with the rear-stage isolation type three-level DC / DC structure through a DC capacitor, the front-stage three-level AC / DC structure rectifies the three-phase alternating voltage input into a stable DC voltage, and the rear-stage isolation type three-level DC / DC structure converts the DC voltage into different stable DC voltages according to different input voltage levels of the load. The power supply device controls the turn-on time and turn-off time of the switch tube through the control method to achieve the purpose of adjusting the output voltage. The application solves the technical problem that the conventional PI control method in the prior art has poor dynamic performance, slow response speed, is sensitive to external disturbance changes, and influences the overall performance of the power supply device system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to a power supply device with adjustable output voltage and a control method of the power supply device with adjustable output voltage. BACKGROUND

[0002] In the field of power electronics, the power supply device composed of AC / DC and DC / DC two-stage structure is a common topology. Among them, the AC / DC structure and the DC / DC structure mostly adopt two-level and three-level converters, such as six-switch voltage type PWM rectifier, I-type NPC three-level converter, T-type three-level converter, two-level / three-level step-down converter, two-level / three-level step-up converter, two-level / three-level step-down / step-up converter. Compared with the traditional two-level converter, the three-level converter has smaller voltage stress on a single switching device, lower switching loss of power switching tube, higher system efficiency, and can realize higher level of voltage output and power output.

[0003] In a direct current ring network power supply system, the load end of the direct current bus is connected to a topology structure of different voltage levels, so the power supply device composed of three-level AC / DC and three-level DC / DC two-stage structure needs a control method to widen the input voltage range of the alternating current side and adjust the output voltage of the direct current side.

[0004] In the prior art, for the two-stage structure power supply, whether it is a front-stage three-level AC / DC structure or a rear-stage isolated three-level DC / DC structure, it is a strongly coupled, multi-variable and nonlinear system. The traditional PI control method has poor dynamic performance, slow response speed, and is sensitive to external disturbance changes, which affects the overall performance of the power supply device system. SUMMARY

[0005] The present application solves the technical problem of the traditional PI control method in the prior art, which has poor dynamic performance, slow response speed, and is sensitive to external disturbance changes, which affects the overall performance of the power supply device system.

[0006] To solve the above problems, the present application provides a power supply device with adjustable output voltage, comprising: a front-stage three-level AC / DC structure, which receives a wide voltage range three-phase alternating current at the input side; a rear-stage isolated three-level DC / DC structure, which is connected to the load end through a direct current bus at the output side; wherein the front-stage three-level AC / DC structure is connected to the rear-stage isolated three-level DC / DC structure through a direct current capacitor, the front-stage three-level AC / DC structure rectifies the three-phase alternating current voltage input to a stable direct current voltage, and the rear-stage isolated three-level DC / DC structure converts the direct current voltage into different stable direct current voltages according to different input voltage levels of the load.

[0007] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: the front stage uses a front-stage three-level AC / DC structure to receive a wide-voltage-range three-phase alternating current input to achieve a stable direct current voltage output, and the rear stage uses a rear-stage isolated three-level DC / DC structure to convert different voltage levels required by a load end; the front-stage three-level AC / DC structure and the rear-stage isolated three-level DC / DC structure are connected through a direct current capacitor, the load end is connected to an output side of the rear-stage isolated three-level DC / DC structure through a direct current bus, and the load can be a DC / DC structure or a DC / AC structure. Meanwhile, the AC / DC and DC / DC two-stage converter of the power supply device adopts a three-level structure converter, and compared with a traditional two-level structure converter, the voltage stress borne by a single switch tube is smaller, the switching loss of a power switch tube is lower, and the system efficiency is higher.

[0008] In an example of the present application, the front-stage three-level AC / DC structure converts the three-phase alternating current into a first direct current voltage; the rear-stage isolated three-level DC / DC structure adopts a first-order linear active disturbance rejection control strategy to convert the first direct current voltage into a second direct current voltage, and adjusts the output to adapt to loads of different voltage level topologies; wherein the amplitude of the second direct current voltage is adjustable.

[0009] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: the front-stage three-level AC / DC structure converts the wide-voltage-input three-phase alternating current into a required stable direct current voltage (that is, a first direct current voltage) through a control method, and the rear-stage isolated three-level DC / DC structure converts the first direct current voltage into a stable direct current voltage (defined as a second direct current voltage) with adjustable amplitude through a control method, and different amplitude voltage levels of the second direct current voltage are suitable for connecting to different loads through a direct current bus, so as to adjust the output to adapt to loads of different voltage level topologies.

[0010] In an example of the present application, the front-stage three-level AC / DC structure adopts a double-loop control strategy of a PI voltage loop + model predictive current control; and the rear-stage isolated three-level DC / DC structure adopts a double-loop control strategy of a first-order linear active disturbance rejection voltage loop + a PI current loop.

[0011] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: the front-stage three-level AC / DC structure adopts a double-loop control strategy of a PI voltage loop + model predictive current control, solving the problem of poor dynamic performance of a PI control strategy; and the rear-stage isolated three-level DC / DC structure adopts a double-loop control strategy of a first-order linear active disturbance rejection voltage loop + a PI current loop, balancing the performance of output side voltage stability and anti-interference, and improving the dynamic response performance of the controller. In the present application, the front-stage three-level AC / DC structure and the rear-stage isolated three-level DC / DC structure are combined to form a power supply device to achieve the purpose of wide-voltage input and adjustable output voltage.

[0012] In another aspect, the application also provides a control method of the output voltage adjustable power supply device, which is applied to the output voltage adjustable power supply device of the first embodiment, and the control method comprises: establishing a value function of a switching vector according to a grid-side current prediction value, a current given value and a DC-side upper and lower capacitor voltage deviation; selecting an optimal switching vector according to the value function, and applying the optimal switching vector to the next control cycle of the front-stage three-level AC / DC structure.

[0013] In an example of the application, before the value function of the switching vector is established according to the grid-side current prediction value, the current given value and the DC-side upper and lower capacitor voltage deviation, the control method further comprises: obtaining an output voltage of the DC-side of the front-stage three-level AC / DC structure, and obtaining a first voltage difference value by subtracting the output voltage from a DC-side voltage reference value; inputting the first voltage difference value to a DC voltage loop PI controller to generate an active current reference value, and setting a reactive current reference value to 0; collecting grid-side three-phase currents, obtaining an active current actual value and a reactive current actual value after matrix coordinate transformation, and setting a reactive current given value to 0; collecting grid-side three-phase voltages, obtaining a voltage required by a phase-locked loop and an angle required by a phase-locked loop output after matrix coordinate transformation; and performing discretization calculation on the grid-side current prediction value at k+1 time and the grid-side current prediction value at k+2 time according to a grid-side prediction current model of the three-level AC / DC structure.

[0014] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: after the grid-side current prediction value at k+1 time and the grid-side current prediction value at k+2 time are discretely calculated according to the grid-side prediction current model of the three-level AC / DC structure, the process of online value function optimization is started, that is, the value of the switching function is preferentially selected as the value corresponding to the optimal switching vector that makes the absolute value gmin of the value function minimum in the switching sequence, and the value is applied to the next control cycle of the front-stage three-level AC / DC structure.

[0015] In an example of the application, the control method further comprises: establishing a linear extended state observer according to a transfer function of the voltage loop, combining an output quantity observation value, a total disturbance observation value and an observer coefficient; obtaining a current loop given quantity by combining the linear extended observer according to a given DC-side voltage and an actual output voltage; collecting an actual current, obtaining a third current difference value by subtracting the actual current from the current loop given quantity, inputting the third current difference value to a current loop PI controller to obtain a control signal, and generating a modulation signal by the control signal through a PWM waveform generator.

[0016] ​​In one example of the present application, the current loop given quantity is obtained according to the given DC side voltage and the actual output voltage in combination with the linear extended observer, including: the DC side voltage is subtracted from the actual output voltage, and the error is gain processed to obtain a second control quantity when the disturbance is not compensated; the total disturbance of the system observed by the linear extended state observer is subtracted from the second control quantity to obtain a second difference value, and the second difference value is divided by a compensation factor to obtain a system control quantity, which is the current loop given quantity.

[0017] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the power supply device in the present application can adjust the output voltage range of the rear-stage isolation type three-level DC / DC structure through the control method, can be suitable for connecting different voltage levels of loads on the DC bus, and can improve the system control performance, robustness and anti-interference performance, so that the system DC side has a wide range of output voltage and fast response under interference.

[0018] In one example of the present application, the three-phase alternating current at the input side of the front-stage three-level AC / DC structure is boosted by an isolation transformer.

[0019] In one example of the present application, the control method further includes: the rear-stage isolation type three-level DC / DC structure adjusts the duty cycle of the control signal of the plurality of switching tubes according to the load connected to the DC bus with different input voltage levels.

[0020] In one example of the present application, the rear-stage isolation type three-level DC / DC structure adjusts the duty cycle of the control signal of the plurality of switching tubes according to the load connected to the DC bus with different input voltage levels, including: collecting the voltage signals of the different load input ends of the DC side of the rear-stage isolation type three-level DC / DC structure; the voltage signals generate control signals through a control link; the control signals generate modulation signals through a PWM waveform generator to the rear-stage isolation type three-level DC / DC structure to control the turn-on time and turn-off time of the plurality of switching tubes, and output different amplitude DC voltages.

[0021] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the front-stage three-level AC / DC structure adopts a model predictive current control strategy to improve the response speed of the system while ensuring that the output side outputs stable DC voltage; the rear-stage isolation type three-level DC / DC structure adopts a double closed-loop control strategy of first-order linear active disturbance rejection voltage loop + PI current loop to adjust the duty cycle of the switching tube, and the output side outputs different amplitude DC voltages. The power supply device controls the turn-on time and turn-off time of the switching tube through the control method to achieve the purpose of adjusting the output voltage.

[0022] After the technical scheme of the present application is adopted, the following technical effects can be achieved:

[0023] (1) The front-stage three-level AC / DC structure adopts a double-loop control strategy of PI voltage loop + model predictive current control, solves the problem of poor dynamic performance of the PI control strategy, and improves the dynamic response performance of the controller; the rear-stage isolated three-level DC / DC structure adopts a double-loop control strategy of first-order linear active disturbance rejection voltage loop + PI current loop, and gives consideration to the performance of output-side voltage stability and anti-interference;

[0024] (2) The power supply device is composed of the front-stage three-level AC / DC structure and the rear-stage isolated three-level DC / DC structure to realize wide voltage input and adjustable output voltage;

[0025] (3) The AC / DC and DC / DC two-stage converters of the power supply device adopt three-level structure converters, and compared with the traditional two-level structure converters, the voltage stress borne by a single switch tube is smaller, the switching loss of the power switch tube is lower, and the system efficiency is higher;

[0026] (4) The power supply device in the application can adjust the output voltage range of the rear-stage isolated three-level DC / DC structure through the control method, can be suitable for connecting loads of different voltage grades on the DC bus, and can improve the system control performance, robustness and anti-interference performance, and ensure that the system DC side has a wide range of output voltage and fast response under interference. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings;

[0028] Figure 1 A system block diagram of the output voltage adjustable power supply device provided by the embodiment of the application is shown in the figure;

[0029] Figure 2 A structure diagram of the front-stage three-level AC / DC structure in the application is shown in the figure; Figure 1

[0030] A control block diagram of the front-stage three-level AC / DC structure is shown in the figure; Figure 3

[0031] A structure diagram of the rear-stage isolated three-level DC / DC structure in the application is shown in the figure; Figure 4 Figure 1 A control block diagram of the rear-stage isolated three-level DC / DC structure is shown in the figure.

[0032] Figure 5

[0033] ​​Reference signs:

[0034] 100 - front-stage three-level AC / DC structure; 101 - voltage loop PI controller; 102 - value function; 103 - predicted current model; 200 - rear-stage isolated three-level DC / DC structure; 201 - current loop PI controller; 202 - linear extended state observer. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application are described clearly and completely. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0036] Embodiment one

[0037] Reference Figure 1 , which is a system block diagram of a power supply device with adjustable output voltage provided by the embodiment of the present application, in combination with Figure 2 and Figure 4 , the power supply device comprises: a front-stage three-level AC / DC structure 100 and a rear-stage isolated three-level DC / DC structure 200. The front-stage three-level AC / DC structure 100 receives a wide voltage range of three-phase alternating current on the input side. The output side of the rear-stage isolated three-level DC / DC structure 200 is connected to the load end through a DC bus. The front-stage three-level AC / DC structure 100 is connected to the rear-stage isolated three-level DC / DC structure 200 through a DC capacitor. The front-stage three-level AC / DC structure converts the three-phase alternating current voltage input into a stable DC voltage. The rear-stage isolated three-level DC / DC structure converts the DC voltage into different stable DC voltages according to different input voltage levels of the load.

[0038] In a specific embodiment, the front stage uses the front-stage three-level AC / DC structure 100 to receive a wide voltage range of three-phase alternating current input to achieve a stable DC voltage output. The rear stage uses the rear-stage isolated three-level DC / DC structure 200 to convert different voltage levels required by the load end. The front-stage three-level AC / DC structure 100 is connected to the rear-stage isolated three-level DC / DC structure 200 through a DC capacitor. The load end is connected to the output side of the rear-stage isolated three-level DC / DC structure 200 through a DC bus. The load can be a DC / DC structure or a DC / AC structure.

[0039] Specifically, the pre-stage three-level AC / DC structure 100 has a pre-stage input terminal and a pre-stage output terminal. The pre-stage input terminal is connected to a wide-range three-phase AC voltage boosted by an isolation transformer, and the pre-stage output terminal outputs a stable DC voltage. The post-stage three-level DC / DC structure 200 has a post-stage input terminal and a post-stage output terminal. The post-stage input terminal is connected to the input terminal of the pre-stage three-level AC / DC structure 100 through a DC capacitor, and the post-stage output terminal is connected to the load on the DC bus through an isolation transformer. The pre-stage three-level AC / DC structure 100 rectifies the three-phase AC voltage input into a stable DC voltage, and the post-stage three-level DC / DC structure 200 converts the DC voltage into different stable DC voltages according to the load with different input voltage levels through a control method.

[0040] The preamplifier three-level AC / DC structure 100 consists of a three-phase type I NPC three-level PWM rectifier bridge circuit, which can convert a wide-range input three-phase AC voltage into a wide-range output DC voltage. It includes three arms of the three-level rectifier bridge, each arm containing four switching transistors, four anti-parallel diodes, and two midpoint clamping diodes. For example... Figure 2 As shown, a three-level rectifier bridge, taking one arm as an example, includes four switching transistors. Four anti-parallel diodes and two clamping diodes , Three-phase input filter inductor L, output support capacitor , , , The switching states are complementary. , The switching states are complementary, and , You cannot activate them at the same time.

[0041] The subsequent isolated three-level DC / DC structure 200 consists of an isolated three-level step-down circuit. It can convert the DC voltage output from the preceding three-level AC / DC structure 100 into an adjustable, stable DC output voltage through a control strategy. For example... Figure 4 As shown, this isolated three-level buck converter circuit includes eight switching transistors. 8 anti-parallel diodes Four clamping diodes, an isolation transformer, and isolation-side rectifier diodes D9 and D2. 10 Filter capacitor C5.

[0042] Further, the front-stage three-level AC / DC structure 100 converts three-phase alternating current into a first direct current voltage; the rear-stage isolated three-level DC / DC structure 200 adopts a first-order linear active disturbance rejection control strategy to convert the first direct current voltage into a second direct current voltage, and adjusts the output to adapt to loads of different voltage level topologies; wherein the amplitude of the second direct current voltage is adjustable.

[0043] Specifically, the front-stage three-level AC / DC structure 100 converts wide-voltage input three-phase alternating current into a required stable direct current voltage (i.e. the first direct current voltage) through a control method, and the rear-stage isolated three-level DC / DC structure 200 converts the first direct current voltage into a stable direct current voltage with adjustable amplitude (defined as the second direct current voltage here) through a control method. The second direct current voltage with different amplitude voltage levels is suitable for connecting to different loads, so as to adjust the output to adapt to loads of different voltage level topologies.

[0044] Further, the front-stage three-level AC / DC structure 100 adopts a double closed-loop control strategy of PI voltage loop + model predictive current control; and the rear-stage isolated three-level DC / DC structure 200 adopts a double closed-loop control strategy of first-order linear active disturbance rejection voltage loop + PI current loop.

[0045] Specifically, the front-stage three-level AC / DC structure 100 adopts a double closed-loop control strategy of PI voltage loop + model predictive current control, which solves the problem of poor dynamic performance of the PI control strategy and improves the dynamic response performance of the controller; and the rear-stage isolated three-level DC / DC structure 200 adopts a double closed-loop control strategy of first-order linear active disturbance rejection voltage loop + PI current loop, which takes into account the performance of output side voltage stability and anti-interference. In this application, the front-stage three-level AC / DC structure 100 and the rear-stage isolated three-level DC / DC structure 200 are combined to form a power supply device to achieve the purpose of wide-voltage input and adjustable output voltage.

[0046] Embodiment Two

[0047] Referring to Figure 3 and Figure 5 , the embodiment also provides a control method of the output voltage adjustable power supply device, the control method being applied to the output voltage adjustable power supply device of the first embodiment, and the control method comprising:

[0048] establishing a value function of a switching vector according to a network side current prediction value, a current given value, and a direct current side upper and lower capacitor voltage deviation;

[0049] selecting an optimal switching vector according to the value function, and applying the optimal switching vector to a next control period of the front-stage three-level AC / DC structure.

[0050] Furthermore, before establishing the value function of the switching vector based on the predicted grid-side current, the current setpoint, and the DC-side upper and lower capacitor voltage deviations, the control method also includes:

[0051] Obtain the output voltage on the DC side of the front-end three-level AC / DC structure, and calculate the difference between the output voltage and the DC side voltage reference value to obtain the first voltage difference value;

[0052] The first voltage difference is input to the DC voltage loop PI controller to generate an active current reference value, and the reactive current reference value is set to 0.

[0053] The three-phase current on the grid side is collected, and the actual values ​​of active current and reactive current are obtained after matrix coordinate transformation. The reactive current setpoint is set to 0.

[0054] The three-phase voltage on the grid side is collected, and after matrix coordinate transformation, the voltage required by the phase-locked loop and the angle required for the phase-locked loop output are obtained.

[0055] Based on the three-level AC / DC structure grid-side predicted current model, the grid-side predicted current values ​​at time k+1 and k+2 are discretized and calculated.

[0056] In one specific embodiment, the control method for the front-end three-level AC / DC structure 100 in the power supply device with adjustable output voltage specifically includes the following process:

[0057] Step S11: Sample the DC-side output voltage of the pre-amplifier three-level AC / DC structure. , and the DC side voltage reference value The difference (i.e., the first voltage difference) is calculated by the DC voltage loop PI controller 101 to generate an active current reference value. The reactive current reference value Set to 0; simultaneously collect the three-phase current on the grid side ( Figure 3 In , and The actual current value of the active current loop is obtained after matrix coordinate transformation. and the actual current value of the reactive current loop Set the reactive current loop setpoint value to 0; grid-side three-phase voltage ( Figure 3 In , and The required voltage for the phase-locked loop is obtained through matrix coordinate transformation. and The required angle for the phase-locked loop output is set to θ. The actual value of the active current is... That is, the actual current value of the active current loop and the actual value of the reactive current loop. The actual current value of the reactive current loop, the reactive current given value is the given value of the reactive current loop.

[0058] Step S12: According to the three-level AC / DC structure grid-side prediction model, the discrete calculation of k+1 time grid-side current prediction value I αβ (k+1) and k+2 time grid-side current prediction value I αβ (k+2) is carried out; Specifically, according to the three-level AC / DC structure grid-side prediction current model 103, there is the following expression:

[0059] ;

[0060] In the formula, L is the grid-side inductance, and R is the equivalent impedance of the line; is the sampling period of the system; is the k+2 time grid-side current prediction value in the two-phase coordinate system; is the k+1 time grid-side current prediction value in the two-phase coordinate system; are the axis component and the axis component of the grid voltage respectively; is the k+1 time grid-side voltage calculation value in the two-phase coordinate system; and the calculation formula is as follows:

[0061] ;

[0062] In the formula, is the k+1 time DC side stable voltage prediction value; , and are the three-phase switching states that may be used in the k+1 period.

[0063] At the same time, the upper and lower DC capacitor voltage deviation prediction model of the front-stage three-level AC / DC structure 100 is established, and the formula is as follows:

[0064] , ;

[0065] In the formula, is the k+2 time DC side upper and lower capacitor voltage deviation; is the k+1 time DC side upper and lower capacitor voltage deviation; C is the DC side capacitor value; is the k+1 time three-phase grid-side current.

[0066] The current given value and The current given value at the k+2 moment can be calculated from the current values at previous moments, and the formula is as follows:

[0067] ;

[0068] In the formula, is the current given value at the k+2 moment in the two-phase αβ coordinate system; is the current given value at the k+1 moment in the two-phase αβ coordinate system; is the current given value at the k moment in the two-phase αβ coordinate system; is the current given value at the k-1 moment in the two-phase αβ coordinate system;

[0069] Step S13: There are 27 switching states for the three-level I-type NPC structure, and in order to select the optimal switching vector, the reference current fast tracking and the midpoint potential balance need to be considered, and the value function 102 of the switching vector is established as follows: ;

[0070] In the formula, is the weight factor of the voltage deviation of the upper and lower capacitors on the DC side, and by setting different values, the priority of the current control and the midpoint balance control can be adjusted; after the value function 102 obtains the optimal switching vector by reasonably selecting values, the PWM modulation link is entered, and the driving signals of the switching tubes are outputted to act on the three-level I-type NPC rectifier.

[0071] Further, the control method further comprises:

[0072] According to the transfer function of the voltage loop, the output quantity observation value, the total disturbance observation value, and the observer coefficient are combined to establish a linear extended state observer;

[0073] According to the given DC side voltage and the actual output voltage, the current loop given quantity is obtained in combination with the linear extended observer;

[0074] The actual current is collected, and the actual current is subtracted from the current loop given quantity to obtain a third current difference value, and the third current difference value is inputted into the current loop PI controller to obtain a control signal, and the control signal is inputted into the PWM waveform generator to generate a modulation signal.

[0075] Further, according to the given DC side voltage and the actual output voltage, the current loop given quantity is obtained in combination with the linear extended observer, which comprises:

[0076] The DC side voltage is subtracted from the actual output voltage, and the error is gain-processed to obtain a second control quantity when the disturbance is not compensated;

[0077] The system total disturbance observed by the linear extended state observer is subtracted from the second control quantity to obtain a second difference value, and the system control quantity is obtained by dividing the second difference value by a compensation factor, and the system control quantity is a current loop given quantity.

[0078] In one specific embodiment, the control method of the output-voltage-adjustable power supply device with the rear-stage isolation three-level DC / DC structure 200 specifically includes the following processes:

[0079] Step S21: The linear active disturbance rejection controller adopted by the voltage loop is usually composed of three parts: a linear tracking differentiator, a linear extended state observer 202, and a linear state error feedback. The linear tracking differentiator is omitted in this application. According to the transfer function of the voltage loop, the linear extended state observer is established, which is specifically represented as: , wherein f is the system total disturbance, y is the output quantity, is a compensation factor, and u is a control quantity.

[0080] For the linear extended state observer 202, the linear extended state observer 202 is designed as: , , , are the observed values of the output quantity and the total disturbance, respectively, , are the derivative state variables of , , , are observer coefficients.

[0081] The state space expression of the linear extended state observer 202 is obtained by designing the linear extended state observer 202: ; in the formula, , , , ;

[0082] According to the above formula and the state observer design principle, the linear extended state observer 202 is designed as: ;

[0083] In the formula, , and are the states of the real-time reconstructed isolation three-level DC / DC mechanism DC voltage and total disturbance, z represents the estimated state of the extended state observer, and T represents the matrix transpose; is the observer gain matrix to be designed, is the observer output estimation value, and the linear extended state observer 202 equation is rewritten again as:

[0084] ;

[0085] In the formula, Here, is the input matrix, u is the input of the linearly extended observer of the controlled object, and y is the output of the linearly extended observer of the controlled object. This is the output state variable of the linear state observer. Using the pole placement method, the gain matrix L is chosen to place all the poles of the LESO characteristic equation within it. At that point, we obtained:

[0086] ;

[0087] In the formula, s is the eigenvalue of the matrix, I is the identity matrix, and A-LC= .

[0088] The final observer gain matrix is: In the formula, This represents the observer bandwidth.

[0089] Step S22: Using the given DC side voltage With actual output voltage The difference is calculated, and the gain is applied to the error to obtain the control quantity without compensation for the disturbance. Specifically, for a first-order linear active disturbance rejection, the disturbance compensation element in the linear state error feedback is as follows:

[0090] ;

[0091] We can obtain: ;

[0092] In the formula, U dc2 This is the actual DC-side voltage value. This represents the control quantity without compensation for disturbances; therefore, a proportional controller can be designed to synthesize this control signal. ;

[0093] In the formula, It is the gain of the proportional controller. Set the voltage value for the voltage loop.

[0094] Step S23: The first-order linear active disturbance rejection voltage loop controller has three controller parameters that need to be designed, namely... , , After determining the parameters, the first-order linear active disturbance rejection voltage loop controller outputs the setpoint of the current loop; specifically, the system disturbance quantity f observed by the linear extended state observer is compared with... Take the difference to obtain the second difference value, then divide the second difference by... The system control quantity u is then obtained, which is the current loop setpoint IL*.

[0095] Step S24: the actual current IL is subtracted from the given amount current IL* to obtain a third current difference value, the third current difference value is input into the current loop PI controller 201 to calculate a modulation signal, the modulation signal and the carrier signal generate a PWM wave as a control signal of the switch tube in the later-stage isolation type three-level DC / DC structure, so as to realize the turn-on time and turn-off time of the switch tube.

[0096] Further, the three-phase alternating current at the input side of the former three-level AC / DC structure is boosted by an isolation transformer.

[0097] Specifically, the wide voltage input at the input end of the former three-level AC / DC structure 100 is boosted by an isolation transformer for the three-phase voltage.

[0098] Further, the control method further comprises:

[0099] The later-stage isolation type three-level DC / DC structure adjusts the duty cycle of the control signal of the plurality of switch tubes to adjust the different input voltage levels of the load connected by the DC bus;

[0100] The voltage signal at the input end of the different loads at the DC side of the later-stage isolation type three-level DC / DC structure is collected;

[0101] The voltage signal generates a control signal through a control link;

[0102] The control signal generates a modulation signal through a PWM waveform generator to the later-stage isolation type three-level DC / DC structure to control the turn-on time and turn-off time of the plurality of switch tubes, and output different amplitude direct current voltages.

[0103] Specifically, the former three-level AC / DC structure 100 adopts a model predictive current control strategy to improve the response speed of the system while ensuring the stable direct current voltage output at the output side; the later-stage isolation type three-level DC / DC structure 200 adopts a double closed-loop control strategy of a first-order linear active disturbance rejection voltage loop + PI current loop to adjust the duty cycle of the switch tube, and output different amplitude direct current voltages at the output side.

[0104] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; 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 power supply device with adjustable output voltage, characterized in that, The power supply device comprises: a front-stage three-level AC / DC structure (100) receiving a wide-voltage-range three-phase alternating current on the input side; a rear-stage isolated three-level DC / DC structure (200) connected to the load end through a DC bus on the output side; wherein the front-stage three-level AC / DC structure (100) is connected to the rear-stage isolated three-level DC / DC structure (200) through a DC capacitor, the front-stage three-level AC / DC structure rectifies the three-phase alternating current into a stable DC voltage, and the rear-stage isolated three-level DC / DC structure converts the DC voltage into different stable DC voltages according to different input voltage levels of the load; The power supply device adopts a control method, and the control method further comprises: According to the transfer function of the voltage loop, the output quantity observation value, the total disturbance observation value and the observer coefficient are combined to establish a linear extended state observer; According to the given DC side voltage and the actual output voltage, the current loop given value is obtained in combination with the linear extended observer; The actual current is collected, and the actual current is subtracted from the current loop given value to obtain a third current difference value, and the third current difference value is input into a current loop PI controller to obtain a control signal, and the control signal is input into a PWM waveform generator to generate a modulation signal; According to the given DC side voltage and the actual output voltage, the current loop given value is obtained in combination with the linear extended observer, which comprises: The DC side voltage is subtracted from the actual output voltage, and the error is gain to obtain a second control quantity when the disturbance is not compensated; The total disturbance of the system observed by the linear extended state observer is subtracted from the second control quantity to obtain a second difference value, and the system control quantity is obtained after the second difference value is divided by a compensation factor. The system control quantity is the current loop given value.

2. The power supply device according to claim 1, wherein: The front-stage three-level AC / DC structure (100) converts the three-phase alternating current into a first DC voltage; The rear-stage isolated three-level DC / DC structure (200) adopts a first-order linear active disturbance rejection control strategy, converts the first DC voltage into a second DC voltage, and adjusts the output to adapt to the load of different voltage level topologies; Wherein, the amplitude of the second DC voltage is adjustable.

3. The power supply device according to claim 1, wherein: The front-stage three-level AC / DC structure (100) adopts a PI voltage loop + model predictive current control double-loop control strategy; The rear-stage isolated three-level DC / DC structure (200) adopts a first-order linear active disturbance rejection voltage loop + PI current loop double-loop control strategy.

4. A control method of an output voltage adjustable power supply device, the control method being applied to the output voltage adjustable power supply device according to any one of claims 1 to 3, characterized by, The control method comprises: According to the network side current prediction value, the current given value and the DC side upper and lower capacitor voltage deviation, a value function of the switching vector is established; According to the value function, the optimal switching vector is selected and applied to the next control period of the front-stage three-level AC / DC structure.

5. The control method according to claim 4, wherein, Before the value function of the switching vector is established according to the grid-side current prediction value, the current given value and the DC-side upper and lower capacitor voltage deviation, the control method further comprises: An output voltage of a DC side of the pre-stage three-level AC / DC structure is acquired, and the output voltage is subtracted from a DC voltage reference value to obtain a first voltage difference value; The first voltage difference value is input to a DC voltage loop PI controller to generate an active current reference value, and a reactive current reference value is set to 0; Three-phase grid-side currents are collected, and active current actual values and reactive current actual values are obtained after matrix coordinate transformation, and a reactive current given value is set to 0; Three-phase grid-side voltages are collected, and voltages required by a phase-locked loop and an angle required by an output of the phase-locked loop are obtained after matrix coordinate transformation; According to a grid-side current prediction model of the three-level AC / DC structure, the grid-side current prediction value at k+1 time and the grid-side current prediction value at k+2 time are calculated.

6. The control method according to claim 4, characterized in that, The three-phase alternating current at the input side of the pre-stage three-level AC / DC structure is boosted by an isolation transformer.

7. The control method according to claim 4, characterized by, The control method further comprises: The post-stage isolation-type three-level DC / DC structure is connected to loads of different input voltage levels through a DC bus, and the duty cycles of control signals of a plurality of switching tubes in the post-stage isolation-type three-level DC / DC structure are adjusted.

8. The control method according to claim 7, characterized in that, The post-stage isolation-type three-level DC / DC structure is connected to loads of different input voltage levels through a DC bus, and the duty cycles of control signals of a plurality of switching tubes in the post-stage isolation-type three-level DC / DC structure are adjusted, comprising: A voltage signal of an input end of the post-stage isolation-type three-level DC / DC structure is collected; The voltage signal generates a control signal through a control link; The control signal generates a modulation signal to the post-stage isolation-type three-level DC / DC structure through the PWM waveform generator to control on and off time of the plurality of switching tubes, and outputs DC voltages of different amplitudes.

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