Control method and device of dual active bridge converter, storage medium and electronic equipment

Abstract

The invention discloses a control method and device of a dual active bridge converter, a storage medium and electronic equipment. Relates to the technical field of power electronics, and the method comprises the steps that voltage information of the dual-active bridge converter and the current phase shift ratio of the dual-active bridge converter are obtained, the voltage information at least comprises the input voltage and the output voltage of the dual-active bridge converter, and the current phase shift ratio represents the phase shift ratio of the dual-active bridge converter at the current moment; determining the transmission power of the dual-active bridge converter by using a power observer based on the voltage information and the current shift phase; a target shift phase ratio is generated based on the transmission power and a plurality of target regulators, the types of the target regulators including: proportional-integral regulators, the target shift phase ratio being a shift phase ratio after adjusting the current shift phase ratio, and the dual active bridge converter is controlled based on the target shift phase ratio. According to the invention, the technical problem of poor control effect of controlling the dual-active bridge converter in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a control method, device, storage medium and electronic equipment of a dual active bridge converter. Background Art

[0002] The dual active bridge converter (DAB) has the characteristics of bidirectional energy flow and simple topology. It can achieve higher switching frequency and lower device loss, thereby improving power density and converter efficiency. Therefore, it is widely used in various types of DC conversion scenarios, such as electric vehicles, DC distribution networks, microgrids, distributed energy and other fields.

[0003] In the related art, the following two methods are generally used to control the DAB converter:

[0004] (1) The dual-loop control of the DAB converter includes two control loops: an outer voltage control loop and an inner high-frequency inductor current control loop. The outer voltage control loop adjusts the output voltage of the DAB converter and generates a current reference for the inner high-frequency inductor current control loop. The inner high-frequency inductor current control loop generates a phase shift duty cycle as a control signal, using the most commonly used single phase shift (SPS) modulation method to control the power transfer between the two sides of the H bridge. However, the high-frequency inductor current must be measured for feedback calculation. The measurement of the DAB high-frequency inductor current requires devices such as wide-bandwidth current sensors, high-sampling rate analog-to-digital converters, and precise and accurate signal processing circuits. Current sensors will bring high equipment costs.

[0005] (2) Predictive current mode control of DAB converters. It uses a predictive control algorithm to increase the bandwidth of the converter's current feedback loop, making it possible to track the current reference within one switching cycle. However, its structure is quite different from the traditional dual-loop control, and its feedforward plus feedback control structure is relatively complex, which is not conducive to the simplified design of the overall model.

[0006] (3) Dual active bridge converter under single voltage loop control. Since the high-frequency transformer isolation link current of the dual active bridge converter is a high-frequency alternating current, it cannot be directly sampled for closed-loop feedback control, and the traditional voltage and current dual closed-loop structure cannot be realized. When the output side load fluctuates, since the inner loop current and power variables are not added to the feedback control, only the output voltage feedback loop provides a shift ratio. In order for the output voltage to follow the reference setting, its transient current is not controlled, which will increase the electrical stress on the device, accelerate the aging of the device, or cause damage to the device. The output voltage cannot return to a stable value in a short time, which will reduce the overall response speed of the system and even cause the entire system to stop running.

[0007] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0008] The embodiments of the present invention provide a control method, device, storage medium and electronic device for a dual active bridge converter, so as to at least solve the technical problem of poor control effect of controlling a dual active bridge converter in the related art.

[0009] According to one aspect of an embodiment of the present invention, a control method for a dual active bridge converter is provided, comprising: obtaining voltage information of the dual active bridge converter and a current shift phase ratio of the dual active bridge converter, wherein the voltage information at least includes: an input voltage and an output voltage of the dual active bridge converter, and the current shift phase ratio represents a shift phase ratio of the dual active bridge converter at a current moment; determining a transmission power of the dual active bridge converter using a power observer based on the voltage information and the current shift phase ratio; generating a target shift phase ratio based on the transmission power and a plurality of target regulators, and controlling the dual active bridge converter based on the target shift phase ratio, wherein the type of the target regulator includes: a proportional-integral regulator, and the target shift phase ratio is a shift phase ratio after adjusting the current shift phase ratio.

[0010] Furthermore, the multiple target regulators include at least: a first regulator and a second regulator, wherein the first regulator is deployed in a voltage control loop, and the second regulator is deployed in a power control loop, the voltage control loop is used to control the input voltage, and the power control loop is used to control the transmission power, and a target shift ratio is generated based on the transmission power and the multiple target regulators, including: based on the first regulator, obtaining a power value of a preset power; based on the power value of the preset power, the second regulator and the transmission power, generating the target shift ratio.

[0011] Furthermore, the parameters of the first regulator are determined in the following manner: determining the open-loop gain of the voltage control loop; determining the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the second regulator based on the open-loop gain of the voltage control loop; determining the parameters of the first regulator based on the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the first regulator.

[0012] Furthermore, the parameters of the second regulator are determined in the following manner: obtaining information about an equivalent leakage inductance of the transformer in the dual active bridge converter and a parasitic resistance in the dual active bridge converter; and determining the parameters of the second regulator based on the information about the equivalent leakage inductance of the transformer and the parasitic resistance.

[0013] Furthermore, based on the information of the equivalent leakage inductance of the transformer and the parasitic resistance, the parameters of the second regulator are determined, including: determining the proportional adjustment coefficient of the second regulator based on the equivalent leakage inductance of the transformer; determining the integral adjustment coefficient of the second regulator based on the information of the parasitic resistance; determining the parameters of the second regulator based on the proportional adjustment coefficient of the second regulator and the integral adjustment coefficient of the second regulator.

[0014] Furthermore, the power observer is obtained in the following manner: determining a voltage signal of a transformer of the dual active bridge converter; decomposing the voltage signal of the transformer using a Fourier decomposition strategy to obtain a decomposition result; obtaining a current on an inductor of the dual active bridge converter, and determining the power observer based on the decomposition result and the current on the inductor.

[0015] Furthermore, based on the target shift phase ratio, the dual active bridge converter is controlled, including: based on the target shift phase ratio, adopting a single phase shift modulation strategy to generate a switching signal, wherein the switching signal is used to control the switching device of the dual active bridge converter; based on the switching signal, the dual active bridge converter is controlled.

[0016] According to another aspect of an embodiment of the present invention, a control device for a dual active bridge converter is provided, comprising: an acquisition unit, used to acquire voltage information of the dual active bridge converter and a current shift phase ratio of the dual active bridge converter, wherein the voltage information at least includes: an input voltage and an output voltage of the dual active bridge converter, and the current shift phase ratio represents the shift phase ratio of the dual active bridge converter at a current moment; a determination unit, used to determine the transmission power of the dual active bridge converter using a power observer based on the voltage information and the current shift phase ratio; a processing unit, used to generate a target shift phase ratio based on the transmission power and a plurality of target regulators, and control the dual active bridge converter based on the target shift phase ratio, wherein the type of the target regulator includes: a proportional-integral regulator, and the target shift phase ratio is a shift phase ratio after adjusting the current shift phase ratio.

[0017] Furthermore, the multiple target regulators include at least: a first regulator and a second regulator, wherein the first regulator is deployed in a voltage control loop, and the second regulator is deployed in a power control loop, the voltage control loop is used to control the input voltage, and the power control loop is used to control the transmission power, and the processing unit includes: a first acquisition subunit, used to acquire a power value of a preset power based on the first regulator; and a generation subunit, used to generate the target shift ratio based on the power value of the preset power, the second regulator and the transmission power.

[0018] Furthermore, the parameters of the first regulator are determined by the following sub-units: a first determination sub-unit, used to determine the open-loop gain of the voltage control loop; a second determination sub-unit, used to determine the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the second regulator based on the open-loop gain of the voltage control loop; and a third determination sub-unit, used to determine the parameters of the first regulator based on the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the first regulator.

[0019] Furthermore, the parameters of the second regulator are determined by the following sub-units: a second acquisition sub-unit, used to obtain information about the equivalent leakage inductance of the transformer in the dual active bridge converter and the parasitic resistance in the dual active bridge converter; and a fourth determination sub-unit, used to determine the parameters of the second regulator based on the information about the equivalent leakage inductance of the transformer and the parasitic resistance.

[0020] Furthermore, the fourth determination subunit includes: a first determination module, used to determine the proportional adjustment coefficient of the second regulator based on the equivalent leakage inductance of the transformer; a second determination module, used to determine the integral adjustment coefficient of the second regulator based on the information of the parasitic resistance; and a third determination module, used to determine the parameters of the second regulator based on the proportional adjustment coefficient of the second regulator and the integral adjustment coefficient of the second regulator.

[0021] Furthermore, the power observer is obtained through the following sub-units: a fifth determination sub-unit, used to determine the voltage signal of the transformer of the dual active bridge converter; a decomposition sub-unit, used to decompose the voltage signal of the transformer using a Fourier decomposition strategy to obtain a decomposition result; a processing sub-unit, used to obtain the current on the inductor of the dual active bridge converter, and determine the power observer based on the decomposition result and the current on the inductor.

[0022] Furthermore, the processing unit also includes: a generating subunit, used to generate a switching signal based on the target phase shift ratio and adopt a single phase shift modulation strategy, wherein the switching signal is used to control the switching device of the dual active bridge converter; and a controlling subunit, used to control the dual active bridge converter based on the switching signal.

[0023] According to another aspect of an embodiment of the present invention, there is also provided an electronic device, comprising: a processor; and a memory for storing executable instructions of the processor; wherein the processor is configured to execute any one of the above-mentioned control methods of a dual active bridge converter by executing the executable instructions.

[0024] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is provided, which stores a computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute any one of the above-mentioned control methods for the dual active bridge converter.

[0025] In the present invention, the voltage information of the dual active bridge converter and the current shift ratio of the dual active bridge converter are obtained, wherein the voltage information at least includes: the input voltage and output voltage of the dual active bridge converter, and the current shift ratio represents the shift ratio of the dual active bridge converter at the current moment; based on the voltage information and the current shift ratio, the transmission power of the dual active bridge converter is determined by using a power observer; based on the transmission power and multiple target regulators, a target shift ratio is generated, and based on the target shift ratio, the dual active bridge converter is controlled, wherein the type of the target regulator includes: a proportional-integral regulator, and the target shift ratio is a shift ratio after adjusting the current shift ratio. Thus, the technical problem of poor control effect of controlling the dual active bridge converter in the related art is solved. In the invention, the transmission power of the dual active bridge converter is calculated by a power observer, and the transmission power is used as a feedback signal to generate a new shift ratio to control the dual active bridge converter. This avoids the situation in the related art where when a given value of the output voltage undergoes a step change, the system power is out of control in a short period of time and produces a large spike, causing the device to be under excessive stress and the single voltage closed-loop system to respond slowly, thereby achieving the technical effect of improving the control efficiency of the dual active bridge converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0027] Figure 1 is a flow chart of an optional control method of a dual active bridge converter according to an embodiment of the present invention;

[0028] Figure 2 is an equivalent working principle diagram of an optional dual active bridge converter according to an embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of an optional double closed-loop control according to an embodiment of the present invention;

[0030] Figure 4 is an optional double closed-loop equivalent control block diagram according to an embodiment of the present invention;

[0031] Figure 5 is a topological structure diagram of an optional DAB module according to an embodiment of the present invention;

[0032] Figure 6 is a schematic diagram of an optional switch state according to an embodiment of the present invention;

[0033] Figure 7 is a schematic diagram of another optional control method of a dual active bridge converter according to an embodiment of the present invention;

[0034] Figure 8 is a schematic diagram of an observation result of input power by an optional power observer according to an embodiment of the present invention;

[0035] Fig. 9 is a schematic diagram of two different inductor current waveforms and their respective observed values ​​before and after a given voltage step according to an optional embodiment of the present invention;

[0036] Fig.10 is a comparison diagram of output voltage responses of an optional single closed-loop system and a double closed-loop system according to an embodiment of the present invention;

[0037] Fig.11 is an input power response comparison diagram of an optional single closed-loop system and a double closed-loop system according to an embodiment of the present invention;

[0038] Fig.12 is a schematic diagram of an optional control device of a dual active bridge converter according to an embodiment of the present invention;

[0039] Fig.13 is a schematic diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0041] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0042] Embodiment 1

[0043] According to an embodiment of the present invention, a method embodiment of an optional control method for a dual active bridge converter is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0044] Figure 1 is a flow chart of an optional control method of a dual active bridge converter according to an embodiment of the present invention, such as Figure 1 As shown, the method comprises the following steps:

[0045] Step S101, obtaining voltage information of the dual active bridge converter and the current shift phase ratio of the dual active bridge converter, wherein the voltage information at least includes: the input voltage and the output voltage of the dual active bridge converter, and the current shift phase ratio represents the shift phase ratio of the dual active bridge converter at the current moment.

[0046] Figure 2 is an equivalent working principle diagram of an optional dual active bridge converter according to an embodiment of the present invention, such as Figure 2 As shown in FIG. 1 , U1(m) (abbreviated as U1) and U2(m) (abbreviated as U2) represent the input and output voltages of the dual active bridge converter, respectively. L (Right now Figure 2 U L (m)) and i L (Right now Figure 2 i L (m)) are the inductor voltage and inductor current, jω represents a complex number, where j is an imaginary unit, ω represents the system frequency, and U AB and U CD They are the output voltage between the primary H-bridge and the input voltage between the secondary H-bridge. Both voltages are high-frequency square wave voltages and are connected to both sides of the high-frequency AC transformer (or high-frequency isolation transformer, or transformer for short) of the dual active bridge converter. Assume the switching frequency is f s , the transformation ratio of the high-frequency isolation transformer is n=1. The diagonal switches in each full bridge are turned on and off at the same time, and the switches on the same bridge arm are turned on and off complementary to each other. That is, assuming that the duty cycle is 50%, there is a phase shift angle Dπ / 2 between the turn-on and turn-off of the corresponding switches on both sides of the full bridge, where D is the phase shift ratio (0<D<1) and T is the switching period. When D>0, U AB Advance U CD , power flows from the primary side to the secondary side; when D<0, U AB Hysteresis U CD , power flows from the secondary side to the primary side. By controlling the high-frequency square wave voltage U AB , U CDThe frequency, phase and amplitude of the inductor are used to control the magnitude and direction of the inductor current and realize smooth switching of the power direction. The power characteristics of the dual active bridge converter during operation can be determined by the transformer equivalent leakage inductance and the square wave voltage sandwiched on both sides of the equivalent leakage inductance.

[0047] The above voltage information may include: input voltage and output voltage of the dual active bridge converter.

[0048] Step S102: Determine the transmission power of the dual active bridge converter using a power observer based on the voltage information and the current shift ratio.

[0049] In this embodiment, the voltage square wave signal at both ends of the transformer can be expanded into odd harmonics such as 1, 3, and 5 through Fourier decomposition. By processing these sinusoidal wave signals, the current and power transmitted on the equivalent leakage inductance of the dual active bridge (i.e., the above-mentioned transmission power) can be obtained.

[0050] Step S103, generating a target shift phase ratio based on the transmission power and multiple target regulators, and controlling the dual active bridge converter based on the target shift phase ratio, wherein the types of target regulators include: proportional-integral regulators, and the target shift phase ratio is a shift phase ratio after adjusting the current shift phase ratio.

[0051] It should be noted that an optional control system of a dual active bridge converter (referred to as the system for short) can be used to execute the control method of the dual active bridge converter provided in this embodiment. The control system of the dual active bridge converter can be a dual closed-loop control structure, including: a voltage control loop (or called a voltage outer loop) and a power control loop (or called a power inner loop). The voltage control loop is used to control the input voltage so that the voltage is stable near a preset voltage, and the power control loop is used to control the transmission power so that the transmission power is stable near a preset power value.

[0052] Figure 3 is a schematic diagram of an optional double closed-loop control according to an embodiment of the present invention, such as Figure 3 As shown, including: U2*: given output voltage value; G PI1 (s): control function of the first PI regulator (PI regulator of the voltage outer loop); G PI2 (s): control function of the second PI regulator (PI regulator of the power inner loop); P in *: given power value; G dib2 (s): From duty cycle D to output DC current i b The transfer function between 2: i b 2: Current before the output capacitor; i c : output side capacitor current; i2: output side load current; Z L (s): load impedance; RL0 : resistance value on the output side; s: used to express the Laplace expression; C2: capacitance value on the output side; IPO: power observer; U2: output voltage.

[0053] In this embodiment, the transmission power Pin can be superimposed on the voltage outer loop (voltage control loop) PI regulator as the feedback amount of the inner loop control (power control loop). By using the principle of double closed-loop control, the voltage outer loop controls the given value of the output inner loop power through the first-level PI regulator (proportional-integral regulator). The inner loop control performs closed-loop tracking of the power signal based on this given value. Through the second-level PI controller (or regulator), the zero-error tracking of the inner loop power is achieved, and the outer voltage loop can achieve zero-error tracking of the output voltage. The inner loop and the outer loop feedback paths work together to generate a new shift ratio D* (corresponding to the target shift ratio).

[0054] The new phase shift ratio D* can be converted into a switching signal (S1-S8) through a single phase shift modulation link to control the dual active bridge converter, thereby achieving precise control of the dual active bridge converter.

[0055] Through the above steps, in the embodiment, the transmission power of the dual active bridge converter is calculated by the power observer, and the transmission power is used as a feedback signal to generate a new shift ratio to control the dual active bridge converter, thereby avoiding the situation in the related art that when the given value of the output voltage undergoes a step change, the power of the system is not controlled in a short time and a large spike is generated, causing the device to be subjected to excessive stress and the single voltage closed-loop system to respond slowly, thereby achieving the technical effect of improving the control efficiency of the dual active bridge converter. In addition, the technical problem of poor control effect of controlling the dual active bridge converter in the related art is solved.

[0056] Optionally, the multiple target regulators include at least: a first regulator and a second regulator, wherein the first regulator is deployed in a voltage control loop and the second regulator is deployed in a power control loop, the voltage control loop is used to control the input voltage, and the power control loop is used to control the transmission power, and a target shift ratio is generated based on the transmission power and the multiple target regulators, including: based on the first regulator, obtaining a power value of a preset power; based on the power value of the preset power, the second regulator and the transmission power, generating a target shift ratio.

[0057] The dual closed-loop control structure can add the observed power (corresponding to the transmission power) as inner loop (corresponding to the power control loop) feedback to the system (control system of the dual active bridge converter) control process, effectively optimizing the control structure of the dual active bridge converter. By reasonably designing the PI regulators of the voltage outer loop and the inner loop, precise control of the voltage outer loop output voltage signal and the inner loop analog input power signal can be achieved. The active power transmitted by the system (corresponding to the transmission power) can be determined by the phase difference (i.e., the phase shift ratio) between the transformer equivalent leakage inductance and the square wave voltage sandwiched on both sides of the equivalent leakage inductance.

[0058] First, the small signal transfer formula between the input power (corresponding to the transmission power) and the shift ratio can be determined, that is, the control object of the inner loop is:

[0059]

[0060] The control object may refer to the object to be controlled by the PI regulator, that is, the object to be controlled by the PI control to achieve the corresponding effect, which may refer to the duty cycle D (i.e., the shift ratio) to the transfer power P of the inner loop. in The transfer function between them, input a duty cycle, and through the control of the PI controller, the ideal input power (corresponding to the preset power) L can be obtained. r Inductance, R s Represents parasitic resistance.

[0061] In the transfer function G PD (s) After that, the double closed-loop equivalent control block diagram of the system is as follows Figure 4 ( Figure 4 , which is an optional double closed-loop equivalent control block diagram according to an embodiment of the present invention, includes: U2*: a given output voltage value; G PI1 (s): control function of the first PI regulator (the PI regulator of the voltage outer loop, corresponding to the first regulator); G PI2 (s): control function of the second PI regulator (PI regulator of the power inner loop, corresponding to the second regulator); P in *: given power value; G dib2 (s): From duty cycle D to output DC current i b The transfer function between 2: i b 2: Current before the output capacitor; i c : output side capacitor current; i2: output side load current; Z L (s): load impedance; R L0 : resistance value on the output side; s: used to express the Laplace expression; C2: capacitance value on the output side; IPO: power observer; U2: output voltage.

[0062] Generating a target shift ratio based on the transmission power and a plurality of target regulators includes: acquiring a power value of a preset power based on a first regulator; and generating a target shift ratio based on the power value of the preset power, a second regulator, and the transmission power.

[0063] like Figure 4 As shown, the given output voltage voltage value (or preset value) U2* is compared with the output voltage U2, and the given value of the power inner loop power (corresponding to the power value of the preset power) is obtained through the first PI regulator (corresponding to the first regulator). Then, the power values ​​of the input power and the preset power are compared, and then the duty cycle is adjusted through the second PI regulator (corresponding to the second regulator) to generate a target shift ratio.

[0064] Optionally, the parameters of the first regulator are determined in the following manner: determining the open-loop gain of the voltage control loop; determining the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the second regulator based on the open-loop gain of the voltage control loop; determining the parameters of the first regulator based on the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the first regulator.

[0065] In the process of setting the parameters of the voltage control loop (voltage outer loop), the control object of the voltage outer loop is:

[0066]

[0067] Among them, Z L0 (s) corresponds to Figure 3 Z L (s) represents the parallel sum of the output side resistance and capacitance, i.e., the output side impedance.

[0068] When the system is a resistive load, the PI controller G is introduced PI1 (s), the outer open-loop transfer function of the double closed-loop system is:

[0069]

[0070] Where R0 is the resistance on the output side, k pw It is the proportional coefficient of the PI regulator of the voltage control loop, that is, kp1, and U0 corresponds to U2, that is, the output voltage.

[0071] The same controller parameter design method as the single-loop control is used to design the outer loop to be one-third slower than the inner loop, which means that the bandwidth of the voltage loop in the double closed loop is 400Hz. PI1 The parameter design process of (s) is:

[0072] In the high frequency band, omitting the integral term of the regulator, the voltage outer loop open-loop gain is:

[0073]

[0074] The calculation formula of kp1 (corresponding to the proportional adjustment coefficient of the first regulator) is:

[0075]

[0076] To ensure the coordination with the power inner loop, if the cutoff frequency is set at about 400 Hz, it can be concluded that kp1=459.4. Specifically, s=jw, j is an operator representing the imaginary part, and w=2*π*f.

[0077] Similarly, in the low frequency band, the proportional term of the regulator can be omitted, and we get:

[0078]

[0079] Get k i1 The calculation formula of (the integral adjustment coefficient of the first regulator) is:

[0080]

[0081] If the frequency is set to 1 Hz and the amplitude is greater than 54 dB, then k i1 =7423.6.

[0082] The parameters of the second regulator are composed of the proportional regulation coefficient of the first regulator and the integral regulation coefficient of the first regulator.

[0083] Optionally, the parameters of the second regulator are determined by: obtaining information about an equivalent leakage inductance of a transformer in a dual active bridge converter and a parasitic resistance in the dual active bridge converter; and determining the parameters of the second regulator based on the information about the equivalent leakage inductance and the parasitic resistance of the transformer.

[0084] In this embodiment, information about the equivalent leakage inductance of the transformer in the dual active bridge converter and the parasitic resistance in the dual active bridge converter can be obtained, and according to a preset calculation formula, parameters of the second regulator can be determined based on the information about the equivalent leakage inductance and parasitic resistance of the transformer.

[0085] Optionally, based on information about the equivalent leakage inductance and parasitic resistance of the transformer, parameters of the second regulator are determined, including: determining a proportional adjustment coefficient of the second regulator based on the equivalent leakage inductance of the transformer; determining an integral adjustment coefficient of the second regulator based on information about the parasitic resistance; and determining parameters of the second regulator based on the proportional adjustment coefficient of the second regulator and the integral adjustment coefficient of the second regulator.

[0086] The control object of the inner loop of the system is a first-order lag system. In order to ensure the rapid response characteristics of the inner loop system to system disturbances, the inner loop PI controller G can be designed according to the zero-pole cancellation method. PI2 (s), that is:

[0087]

[0088] Among them, kp2 represents the proportional adjustment coefficient of the second regulator, and ki2 can represent the integral adjustment coefficient of the second regulator.

[0089] At this time, the open-loop transfer function of the inner loop of the system is as follows:

[0090]

[0091] in, After the inner loop transfer function is corrected by the PI regulator, the bandwidth of the system can be about 1200Hz, and its response speed is fast. At this time, in order to facilitate the design of the system outer loop regulator, in the inner loop control, Set as input, P in As the output, the closed-loop transfer function of the inner loop system is derived:

[0092]

[0093] After determining the parameters of the PI controller, when the system operates under specified conditions, the system can control the on and off of the dual active bridge switch tube according to the shift phase given by the regulator, so that the dual active bridge converter reaches the preset operating state.

[0094] Optionally, the power observer is obtained by: determining a voltage signal of a transformer of a dual active bridge converter; decomposing the voltage signal of the transformer using a Fourier decomposition strategy to obtain a decomposition result; obtaining a current on an inductor of the dual active bridge converter, and determining a power observer based on the decomposition result and the current on the inductor.

[0095] The voltage square wave signal at both ends of the transformer is decomposed by Fourier to obtain a sinusoidal signal (corresponding to the decomposition result), and its expression is as follows:

[0096]

[0097] U ab with U cd They are the voltage sinusoidal signals on the primary and secondary sides of the transformer, U1 and U2 represent the input and output voltages of the dual active bridge converter, m is the harmonic order, and n is the high-frequency transformer ratio.

[0098] By using the observation and calculation method to measure the current instead of the traditional sensor sampling method, the transmission inductor current on the leakage inductance of the dual active bridge (corresponding to the current on the inductor of the dual active bridge converter) can be obtained in real time:

[0099]

[0100] L is the equivalent leakage inductance of the high-frequency transformer, and ω is the system frequency.

[0101] Active power P L It is expressed as the product of voltage and inductor current:

[0102]

[0103] Ignore the higher harmonics and keep only the fundamental wave. Assume that the transformer has no excitation current and the converter has no loss. The system input power P in That is the power P transmitted on the inductor Lr , the calculation formula of the power observer in this embodiment is:

[0104]

[0105] The voltage square wave signal at both ends of the transformer is decomposed by Fourier to obtain a sinusoidal signal, including:

[0106] During the operation of the dual active bridge, the voltage converted to both ends of the inductor is:

[0107]

[0108] Using the harmonic analysis method, U AB Expanded into Fourier series, that is, expanded into an AC sine waveform:

[0109]

[0110] Because U CD Hysteresis U AB The phase of is Dπ, then U CD The Fourier expansion of is:

[0111]

[0112] It can be seen that the waveform obtained by decomposing the square wave contains only odd-order harmonic components, and the phasor form of its m-th harmonic is:

[0113]

[0114] In summary, based on the Fourier decomposition and calculation of the square wave signal, the real-time transmission power of the dual active bridge converter can be calculated by inputting the voltage shift phase D on both sides, thus achieving the purpose of calculating the real-time transmission power of the dual active bridge converter.

[0115] Optionally, the dual active bridge converter is controlled based on the target shift phase ratio, including: based on the target shift phase ratio, using a single phase shift modulation strategy to generate a switching signal, wherein the switching signal is used to control the switching device of the dual active bridge converter; based on the switching signal, the dual active bridge converter is controlled.

[0116] Figure 5 is a topological structure diagram of an optional DAB module according to an embodiment of the present invention, such as Figure 5 As shown, the DAB module consists of a set of completely symmetrical H-bridges and a high-frequency isolation AC transformer. The H-bridge on each side consists of four switch tubes (S1~S4 / S5~S8) and four reverse parallel diodes (D1~D4 / D5~D8). The full bridges on both sides are connected to the primary and secondary sides of the high-frequency isolation transformer through the transformer equivalent leakage inductance Lr. U1 and U2 are the DC voltages on the input and output sides respectively, n is the transformation ratio of the high-frequency isolation transformer, U AB with U CD are the equivalent voltages of the H bridge at both ends, U L is the voltage on the inductor. During operation, UL=nU AB -U CD , while i L is the current transmitted through the inductor.

[0117] The new phase shift ratio D* is converted into a switching signal S1-S8 through a single phase shift modulation link to control the dual active bridge, thus achieving precise control of the converter. Under the single phase shift modulation control mode, the working waveform of the module is Figure 6 is a schematic diagram of an optional switch state according to an embodiment of the present invention, the switch state is as follows Figure 6 As shown, the states of s1-s8 are high when the corresponding switch is turned on, and 0 when it is turned off. In this working state, the converter has 6 intervals (i.e., t1 to t6) in one working cycle, and the voltage on the inductor and the inductor current periodically jump around the 0 axis as the output voltage changes.

[0118] Figure 7 is a schematic diagram of another optional control method of a dual active bridge converter according to an embodiment of the present invention, such as Figure 7As shown, the dual active bridge converter input voltage U1, output voltage U2, and phase shift ratio D can be calculated through the power observer to obtain the input power Pin (corresponding to the transmission power) through power observation, and a new phase shift ratio can be generated through dual closed-loop control of the outer loop voltage and the inner loop power, and single phase shift control can be performed to perform pulse width modulation (PWM).

[0119] Figure 8 is a schematic diagram of an optional power observer observing the input power according to an embodiment of the present invention, such as Figure 8 As shown, the simulation waveforms of the observed power and the actual input power when the given voltage step is 10% are given. It can be seen that the power observer of this embodiment not only has almost no error with the true value in the steady state, but also can track the change of the true value well when the system is in a transient process. The designed observer has good dynamic performance.

[0120] Fig. 9 is a schematic diagram of two different inductor current waveforms and their respective observed values ​​before and after a given voltage step according to an optional embodiment of the present invention, such as Fig. 9 As shown, when the system is running stably, there is U AB =nU CD At this time, the voltage across the inductor only has a phase change, and there is no difference in amplitude. The voltage on the inductor can only have three values, that is, the waveform of the inductor current presents a trapezoidal wave state. AB ≠nU CD When the voltage across the inductor is 4, the slope of the inductor current waveform will have four values. It can be seen that the waveform of OBS (the waveform of the observed value) is basically consistent with the waveform of REL (the waveform of the actual value). Both are symmetrical with the time axis and are periodically changing waveforms. When the waveform of REL changes, OBS can also simulate its changes well.

[0121] Fig.10 is a comparison diagram of output voltage responses of an optional single closed-loop system and a double closed-loop system according to an embodiment of the present invention, such as Fig.10 As shown in the figure, it can be seen from the simulation waveform that when facing an output voltage step, the dual closed-loop control has less oscillation than the single closed-loop control, and the overshoot of the output voltage is reduced. The system shows better dynamic characteristics under dual closed-loop control.

[0122] Fig.11 is an input power response comparison diagram of an optional single closed-loop system and a double closed-loop system according to an embodiment of the present invention, such as Fig.11As shown, it can be seen from the simulation waveform that when facing an output voltage step, the peak value of the input power of the dual closed-loop control is greatly reduced compared with the single closed-loop control, and the dual closed-loop control greatly reduces the stress on the switching device.

[0123] In this embodiment, based on Fourier decomposition theory, a new method is used to measure the input and output voltages of the dual active bridge converter. By converting the square wave signals at both ends of the transformer into sinusoidal signals, the current can be measured by observation and calculation to replace the traditional sensor sampling method, so as to achieve the purpose of obtaining the active power transmitted on the leakage inductance of the dual active bridge in real time. Then, based on the result of the power observer, on the basis of the dual closed-loop feedback control principle of the voltage outer loop and the power inner loop, the dual active bridge converter is precisely controlled, which not only improves the stability and control accuracy of the system, but also effectively reduces the overshoot of the output voltage and the peak value of the input power generated at a given step, and at the same time improves the response speed of the output voltage.

[0124] Embodiment 2

[0125] Embodiment 2 of the present invention provides an optional control device for a dual active bridge converter, wherein each implementation unit in the control device for the dual active bridge converter corresponds to each implementation step in Embodiment 1.

[0126] Fig.12 is a schematic diagram of an optional control device for a dual active bridge converter according to an embodiment of the present invention, such as Fig.12 As shown, the control device includes: an acquisition unit 121, a determination unit 122, and a processing unit 123.

[0127] An acquisition unit 121 is used to acquire voltage information of the dual active bridge converter and a current shift phase ratio of the dual active bridge converter, wherein the voltage information at least includes: an input voltage and an output voltage of the dual active bridge converter, and the current shift phase ratio indicates a shift phase ratio of the dual active bridge converter at a current moment;

[0128] A determination unit 122, configured to determine the transmission power of the dual active bridge converter using a power observer based on the voltage information and the current shift ratio;

[0129] The processing unit 123 is used to generate a target shift phase ratio based on the transmission power and multiple target regulators, and control the dual active bridge converter based on the target shift phase ratio, wherein the types of target regulators include: proportional-integral regulators, and the target shift phase ratio is a shift phase ratio after adjusting the current shift phase ratio.

[0130] In the control device of the dual active bridge converter provided in the second embodiment of the present invention, the voltage information of the dual active bridge converter and the current shift ratio of the dual active bridge converter can be obtained by the acquisition unit 121, wherein the voltage information at least includes: the input voltage and the output voltage of the dual active bridge converter, the current shift ratio represents the shift ratio of the dual active bridge converter at the current moment, the transmission power of the dual active bridge converter is determined by the determination unit 122 based on the voltage information and the current shift ratio using a power observer, the target shift ratio is generated based on the transmission power and multiple target regulators by the processing unit 123, and the dual active bridge converter is controlled based on the target shift ratio, wherein the types of target regulators include: proportional-integral regulators, and the target shift ratio is a shift ratio after adjusting the current shift ratio.

[0131] Optionally, in the control device of the dual active bridge converter provided in Embodiment 2 of the present invention, the multiple target regulators include at least: a first regulator and a second regulator, wherein the first regulator is deployed in a voltage control loop and the second regulator is deployed in a power control loop, the voltage control loop is used to control the input voltage, and the power control loop is used to control the transmission power, and the processing unit includes: a first acquisition subunit, used to acquire a power value of a preset power based on the first regulator; and a generation subunit, used to generate a target shift ratio based on the power value of the preset power, the second regulator and the transmission power.

[0132] Optionally, in the control device of the dual active bridge converter provided in Embodiment 2 of the present invention, the parameters of the first regulator are determined by the following sub-units: a first determination sub-unit, used to determine the open-loop gain of the voltage control loop; a second determination sub-unit, used to determine the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the second regulator based on the open-loop gain of the voltage control loop; and a third determination sub-unit, used to determine the parameters of the first regulator based on the proportional adjustment coefficient of the first regulator and the integral adjustment coefficient of the first regulator.

[0133] Optionally, in the control device of the dual active bridge converter provided in Example 2 of the present invention, the parameters of the second regulator are determined by the following sub-units: a second acquisition sub-unit, used to obtain information on the equivalent leakage inductance of the transformer in the dual active bridge converter and the parasitic resistance in the dual active bridge converter; and a fourth determination sub-unit, used to determine the parameters of the second regulator based on the information on the equivalent leakage inductance and parasitic resistance of the transformer.

[0134] Optionally, in the control device of the dual active bridge converter provided in Embodiment 2 of the present invention, the fourth determination subunit includes: a first determination module, used to determine the proportional adjustment coefficient of the second regulator based on the equivalent leakage inductance of the transformer; a second determination module, used to determine the integral adjustment coefficient of the second regulator based on information of the parasitic resistance; and a third determination module, used to determine the parameters of the second regulator based on the proportional adjustment coefficient of the second regulator and the integral adjustment coefficient of the second regulator.

[0135] Optionally, in the control device of the dual active bridge converter provided in Example 2 of the present invention, the power observer is obtained through the following sub-units: a fifth determination sub-unit, used to determine the voltage signal of the transformer of the dual active bridge converter; a decomposition sub-unit, used to decompose the voltage signal of the transformer using a Fourier decomposition strategy to obtain a decomposition result; a processing sub-unit, used to obtain the current on the inductor of the dual active bridge converter, and determine the power observer based on the decomposition result and the current on the inductor.

[0136] Optionally, in the control device of the dual active bridge converter provided in Example 2 of the present invention, the processing unit also includes: a generating subunit, used to generate a switching signal based on the target phase shift ratio and adopting a single phase shift modulation strategy, wherein the switching signal is used to control the switching device of the dual active bridge converter; and a controlling subunit, used to control the dual active bridge converter based on the switching signal.

[0137] The control device of the above-mentioned dual active bridge converter may also include a processor and a memory. The above-mentioned acquisition unit 121, determination unit 122, processing unit 123, etc. are all stored in the memory as program units, and the processor executes the above-mentioned program units stored in the memory to realize corresponding functions.

[0138] The processor includes a kernel, and the kernel retrieves the corresponding program unit from the memory. One or more kernels can be set, and the transmission power of the dual active bridge converter is calculated by adjusting the kernel parameters through the power observer, and the transmission power is used as a feedback signal to generate a new shift ratio to control the dual active bridge converter, thereby avoiding the situation in the related art that when the given value of the output voltage undergoes a step change, the power of the system is uncontrolled in a short time and a large spike is generated, causing the device to be subjected to excessive stress and the single voltage closed-loop system to respond slowly, thereby achieving the technical effect of improving the control efficiency of the dual active bridge converter.

[0139] The above-mentioned memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one storage chip.

[0140] According to another aspect of an embodiment of the present invention, there is also provided an electronic device, comprising: a processor; and a memory for storing executable instructions of the processor; wherein the processor is configured to execute any one of the above-mentioned control methods of a dual active bridge converter by executing the executable instructions.

[0141] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is provided, which stores a computer program, wherein when the computer program is running, the device where the computer-readable storage medium is located is controlled to execute any one of the above-mentioned control methods for the dual active bridge converter.

[0142] Fig.13 is a schematic diagram of an electronic device according to an embodiment of the present invention, such as Fig.13 As shown, an embodiment of the present invention provides an electronic device 130, which includes a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, any one of the above-mentioned control methods of the dual active bridge converter is implemented.

[0143] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0144] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0145] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0146] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0147] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0148] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0149] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A control method for a dual active bridge converter, characterized in that: include: Acquire voltage information of a dual active bridge converter and a current shift phase ratio of the dual active bridge converter, wherein the voltage information at least includes: an input voltage and an output voltage of the dual active bridge converter, and the current shift phase ratio represents a shift phase ratio of the dual active bridge converter at a current moment; Determining the transmission power of the dual active bridge converter using a power observer based on the voltage information and the current shift ratio; Based on the transmission power and multiple target regulators, a target shift phase ratio is generated, and based on the target shift phase ratio, the dual active bridge converter is controlled, wherein the types of the target regulators include: a proportional-integral regulator, and the target shift phase ratio is a shift phase ratio after adjusting the current shift phase ratio.

2. The control method according to claim 1, characterized in that: The multiple target regulators include at least: a first regulator and a second regulator, wherein the first regulator is deployed in a voltage control loop, and the second regulator is deployed in a power control loop, the voltage control loop is used to control the input voltage, and the power control loop is used to control the transmission power. Based on the transmission power and the multiple target regulators, a target shift ratio is generated, including: Based on the first regulator, obtaining a power value of a preset power; The target shift ratio is generated based on the power value of the preset power, the second regulator, and the transmission power.

3. The control method according to claim 2, characterized in that: The parameters of the first regulator are determined by: determining an open loop gain of the voltage control loop; Determining a proportional adjustment coefficient of the first regulator and an integral adjustment coefficient of the second regulator based on an open-loop gain of the voltage control loop; Based on a proportional regulation coefficient of the first regulator and an integral regulation coefficient of the first regulator, a parameter of the first regulator is determined.

4. The control method according to claim 3, characterized in that: The parameters of the second regulator are determined by: Acquiring information about an equivalent leakage inductance of a transformer in the dual active bridge converter and a parasitic resistance in the dual active bridge converter; Based on the information of the equivalent leakage inductance of the transformer and the parasitic resistance, parameters of the second regulator are determined.

5. The control method according to claim 4, characterized in that: Determining parameters of the second regulator based on information about the equivalent leakage inductance of the transformer and the parasitic resistance includes: determining a proportional adjustment coefficient of the second regulator based on an equivalent leakage inductance of the transformer; determining an integral adjustment coefficient of the second regulator based on the information of the parasitic resistance; Based on a proportional regulation coefficient of the second regulator and an integral regulation coefficient of the second regulator, a parameter of the second regulator is determined.

6. The control method according to claim 4, characterized in that: The power observer is obtained in the following way: Determining a voltage signal of a transformer of the dual active bridge converter; Decomposing the voltage signal of the transformer by using Fourier decomposition strategy to obtain a decomposition result; A current on an inductor of the dual active bridge converter is obtained, and the power observer is determined based on the decomposition result and the current on the inductor.

7. The control method according to claim 1, characterized in that: Based on the target shift ratio, controlling the dual active bridge converter includes: Based on the target phase shift ratio, a single phase shift modulation strategy is adopted to generate a switching signal, wherein the switching signal is used to control the switching device of the dual active bridge converter; Based on the switching signal, the dual active bridge converter is controlled.

8. A control device for a dual active bridge converter, characterized in that: include: An acquisition unit, used to acquire voltage information of a dual active bridge converter and a current shift phase ratio of the dual active bridge converter, wherein the voltage information at least includes: an input voltage and an output voltage of the dual active bridge converter, and the current shift phase ratio represents a shift phase ratio of the dual active bridge converter at a current moment; A determination unit, configured to determine the transmission power of the dual active bridge converter using a power observer based on the voltage information and the current shift ratio; A processing unit is used to generate a target shift phase ratio based on the transmission power and multiple target regulators, and control the dual active bridge converter based on the target shift phase ratio, wherein the types of the target regulators include: a proportional-integral regulator, and the target shift phase ratio is a shift phase ratio after adjusting the current shift phase ratio.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, wherein when the computer program is executed, the device where the computer-readable storage medium is located is controlled to execute the control method of the dual active bridge converter according to any one of claims 1 to 7.

10. An electronic device, characterized in that: It includes one or more processors and a memory, wherein the memory is used to store one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the control method of the dual active bridge converter described in any one of claims 1 to 7.

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