An electric vehicle power mutual aid device in constant power mode and its control method

Abstract

The application designs a constant power mode electric vehicle power interconnection device and a control method thereof, the device comprises: a battery unit, a Boost step-up conversion unit, a double active bridge step-up converter (DAB), a voltage / current sensor, an A / D module, an IGBT driving module, a UDE-based robust voltage controller; considering that the electric vehicle fast charging standard is a constant power active load, and the circuit tracking error caused by external interference and the uncertainty of the system and the load characteristics, the UDE-based robust control is modeled by using the constant power load, the stable boundary is given, and a UDE-based robust voltage controller is adopted for the load electric vehicle with different circuit parameters, so as to improve the robustness of the system and realize high-precision tracking. The charging demand of different types of electric vehicles is met, and a technical basis is provided for the electric energy interconnection of electric vehicles.

Description

Technical Field

[0001] The present invention belongs to the field of circuit devices or systems for power supply and distribution, and specifically relates to an electric vehicle power mutual aid device in a constant power mode and a control method thereof. Background Art

[0002] With the global fossil fuel crisis and increasingly severe ecological and environmental pollution, new energy vehicles, represented by electric vehicles, are poised to become the mainstream of the future automotive industry. However, range anxiety is a major obstacle to the development of electric vehicles, and the limited number of charging stations significantly limits their range. Therefore, an emergency energy supply solution for electric vehicles is urgently needed. Wallbox previously released a device called Quasar, which allows electric vehicles to provide power to the outside world, but it cannot be used between two electric vehicles.

[0003] Based on the relevant technical requirements of the national standard, this device needs to achieve constant power output. However, the constant power signal exhibits a negative resistance increment, which seriously affects the stability of the device. One solution is to introduce a passive damping network into the converter system to improve system stability, but passive components will cause additional power loss and reduce efficiency. Active damping solutions have also been proposed to improve stability and reduce power loss, but traditional active damping solutions imitate passive components in a way that may conflict with other control objectives.

[0004] Furthermore, to suppress interference and uncertainty, various types of disturbance rejection control (DRC) have been proposed. Within frequency-domain DRC, the disturbance observer (DOB) has been widely used in control systems. It utilizes a disturbance estimation filter to compensate for disturbances. By selecting an appropriate disturbance estimation filter, disturbance rejection can be easily achieved. Compared to frequency-domain DRC, time-domain DRC is more suitable for multiple-input, multiple-output (MIMO) systems.

[0005] Among the known devices for externally powering electric vehicles is the Quasar device announced by Wallbox. However, this device requires significant modifications to existing electric vehicles, is expensive, and is not specifically designed for vehicle-to-vehicle power supply. Therefore, it is difficult to popularize and promote the use of electric vehicles for external power supply. To overcome the shortcomings of this device and achieve inter-vehicle power sharing without significant vehicle modifications, it is crucial to select a suitable boost topology that operates with high voltage gain and high power density, and a control strategy that can maintain stable output voltage despite circuit parameter uncertainty and external disturbances during inter-vehicle power supply.

[0006] Traditional boost converters struggle to achieve high voltage gain and high power density. New boost converters have been proposed, such as multi-level boost converters and diode-capacitor boost converters. However, due to electromagnetic saturation, they are difficult to apply in high-power density environments.

[0007] Research on control strategies for devices reveals that constant-power loads, characterized by negative impedance and nonlinearity, can easily lead to low-frequency and subsynchronous oscillations in the system. The characteristics of the battery output of electric vehicles result in a low power supply short-circuit ratio, adversely affecting circuit stability. To achieve stable operation of boost converters with both a weak power supply and a constant-power load, passive damping control techniques, which add passive components such as capacitors and resistors, were first proposed to achieve stable system operation. However, the addition of physical components increases system cost and power consumption. Based on this, active damping techniques using virtual impedance injection have been proposed, which can improve the system's stable operating margin and response speed. However, these control strategies are difficult to adapt to multiple types of electric vehicles simultaneously, and suffer from problems such as poor versatility and low tolerance.

[0008] Due to its soft-switching capabilities, DAB enables isolated bidirectional power transmission and has been widely adopted in industrial applications, including DC microgrids, on-board chargers, and electric aircraft. However, system nonlinearity and external interference, such as dead-time effects, power device on-state voltage drops, and load variations, can lead to tracking errors in the DAB output voltage.

[0009] Phase-shift control is one of the most commonly used control methods for DAB. Single-phase-shift control is simple and easy to feedback-adjust, but it only controls the power output of the system by adjusting a single variable. It cannot adjust characteristics such as the system's return power and current stress, hindering converter efficiency. Extended phase-shift control, by adding an inner phase shift in the primary-side bridge, increases control freedom and reduces the converter's return power to a certain extent. Based on dual phase-shift control, the same inner phase shift is introduced in both H-bridges, in addition to the outer phase shift. Based on an analysis of factors influencing DAB's soft switching characteristics and return power, a piecewise linear control approach is employed to improve return power. Compared to extended phase-shift control, dual phase-shifting better reduces return power and expands the soft switching range at light loads. Triple phase-shift control presents a multitude of operating modes for DAB, and the mathematical model for return power is complex, making it difficult to generalize in practical engineering applications. Digitally controlled DABs suffer from at least one computational delay. This time delay results in additional phase lag, compromising system stability. Summary of the Invention

[0010] In view of the deficiencies in the prior art, the present invention provides an electric vehicle power mutual aid device in a constant power mode and a control method thereof.

[0011] An electric vehicle power mutual aid device in a constant power mode includes: a battery unit, a Boost boost conversion unit, a dual active bridge boost conversion unit, a voltage / current sensor, an A / D module, an IGBT drive module, and a robust voltage controller based on UDE;

[0012] The Boost converter unit has an input end connected to the battery of the energy supply vehicle and an output end connected to the dual-active bridge-type boost converter unit; the dual-active bridge-type boost converter unit has an input end connected to the Boost converter unit and an output end connected to the load vehicle; the voltage / current sensor has an input end connected to the dual-active bridge-type boost converter unit and an output end connected to the A / D module; the A / D module has an input end connected to the voltage / current sensor and an output end connected to the UDE-based robust voltage controller; the UDE-based robust voltage controller has an input end connected to the A / D module and an output end connected to the IGBT driver module; the IGBT driver module has an input end connected to the UDE-based robust voltage controller and an output end connected to the dual-active bridge-type boost converter unit;

[0013] The dual-active bridge-type boost conversion unit is composed of two symmetrical H-bridges on the primary and secondary sides, a path inductor L, an output-side capacitor C, and a high-frequency transformer that isolates the primary and secondary bridges. The transformer has a transformation ratio of 1:n. The two symmetrical H-bridges on the primary and secondary sides are composed of fully controlled power devices Q1 to Q8. Q1 to Q4 are connected in parallel with the path inductor L, which is also connected in parallel with the fully controlled power devices Q5 to Q8 and the output-side capacitor C. All of these are connected in parallel with the high-frequency transformer that isolates the primary and secondary bridges.

[0014] On the other hand, a method for controlling an electric vehicle power mutual aid device in a constant power mode specifically comprises the following steps:

[0015] Step 1: Connect the battery voltage of the energy-supplying electric vehicle to the Boost converter circuit through a powered wire and an electric clamp with positive and negative polarity, and connect the energy-consuming vehicle directly to the power output port of the dual-active bridge boost converter circuit through the charging port; the on-board battery power supply is a weak power supply, and the weak power supply is equivalent to the Thevenin equivalent circuit of the power supply series inductor; the equivalent inductance L = 1 / SCR [pu], SCR is called the minimum short-circuit ratio, which is often used to characterize the strength of the power grid and belongs to a weak power input system. Finally, the boost converter unit voltage is equivalent to the input voltage V dc , the input current is i u ;

[0016] Step 2: The battery unit transmits its equivalent voltage signal to the Boost conversion unit, and the input voltage V dcAfter passing through the Boost conversion unit, a local boost is performed to the voltage V in Output;

[0017] The Boost converter unit is modeled using the generalized average model of Thevenin equivalent impedance. The average modeling is shown below:

[0018]

[0019]

[0020] Among them, u u Indicates the duty cycle in the Boost circuit, ΔL gu Indicates the Thevenin equivalent inductance, L u Indicates the path inductance in the Boost circuit, ΔC u Indicates the capacitance uncertainty caused by parasitic capacitance; V in is the output voltage of the Boost circuit, C u is the output capacitance of the Boost circuit, V dc Indicates the input voltage of the battery unit connected to the Boost circuit, i u is the path current of the Boost circuit, i in is the output current of the Boost circuit;

[0021] Step 3: Based on the local boost signal V obtained in step 2 in , accessing a high-voltage-gain dual-active bridge-type boost conversion unit through the power input port; the dual-active bridge-type boost conversion unit collects the voltage value after the initial boost of the Boost circuit through the power input port, and performs a stable boost conversion on the input voltage by changing the transformation ratio of the internal transformer;

[0022] When the dual-active bridge boost conversion unit uses a single-phase shift SPS to modulate the internal transformer of the dual-active bridge boost conversion unit, if F s is the switching frequency, D is the phase shift angle, and the fixed duty cycle is 50%. At this time, the transfer power of the input port and output port of the dual active bridge boost conversion unit is:

[0023]

[0024] Where V in represents the input voltage of the dual active bridge boost converter unit, L represents the inductance of the transformer, V o represents the output voltage of the dual-active bridge boost conversion unit; n represents the transformation ratio of the transformer;

[0025] By modulating the corresponding transformer ratio, the input voltage V inReach the rated voltage V required for charging electric vehicles out ;

[0026] Step 4: Based on the phase-shift modulation strategy and boost process described in step 3, the circuit structure and phase-shift modulation method of the DAB boost conversion unit are integrated and reconstructed by integrating the circuit structure of the dual-active bridge boost conversion unit. The dynamic current model of the dual-active bridge boost conversion unit is obtained, which provides a general linear model for the robust voltage controller based on UDE.

[0027] The general linear model is given by UDE for the output voltage V o Tracking reference voltage V ref Perform collection and calculation to obtain the corresponding current tracking value m ref The current tracking quantity is used as the input of the dual-active bridge boost conversion unit. The control quantity is obtained by performing time delay calculation and phase conversion on the current tracking quantity to drive the dual-active bridge boost conversion unit to work. The dual-active bridge boost conversion circuit outputs a dynamic current m. This current is a dynamically changing current, so the model is a dynamic linear model. m is finally decomposed into the current i passing through the output capacitor of the dual-active bridge boost conversion unit. c and the output port current i of the dual active bridge boost converter unit o ,i o It is returned to the UDE-based robust voltage controller as a closed-loop input;

[0028] The UDE-based robust voltage controller initializes the output voltage V of the dual active bridge boost converter unit. o The dynamic output current m is obtained through the dual active bridge boost conversion unit circuit structure and phase shift modulation strategy, and then the estimated value of the output current m is obtained through the disturbance estimator. ref , the estimated value m ref The input is fed into the robust voltage controller to obtain the actual controller component, thereby obtaining the control signal of the IGBT drive module, and finally driving the dual active bridge boost converter unit to work;

[0029] The specific operation includes initializing the output voltage, and the output voltage obtained by initialization according to Kirchhoff's law is:

[0030] V out =V o -V in

[0031] Among them, V o is the output voltage of the dual active bridge boost converter unit, V out is the actual charging input voltage of the final electric vehicle, V inThe output voltage of the Boost circuit is simultaneously used as the input voltage of the dual active bridge voltage conversion unit;

[0032] The dynamic current model of the dual active bridge voltage conversion unit is rewritten as:

[0033]

[0034]

[0035] where C is the output capacitance of the dual active bridge voltage conversion unit;

[0036] At this time, the specific current m ref The phase shift angle is:

[0037]

[0038] Step 5: Based on the reconstructed dynamic current model of the dual active bridge voltage conversion unit in step 4, the voltage / current sensor converts the output current m of the dual active bridge voltage conversion unit into a digital signal and transmits it as input to the UDE-based robust voltage controller; that is, the UDE-based robust voltage controller is designed based on the current model of the dual active bridge voltage conversion unit, at this time, if the output of the robust controller is directly designed as the phase shift angle, the controller will lose its universality, but since the current model is the same, the current-oriented controller design concept can simplify the design of the controller, at this time, the current tracking error caused by the phase shift angle D should be considered in the design of the controller to compensate for the non-deterministic nature of the system and the tracking error of the voltage, considering the system characteristics, external disturbances, and uncertainties caused by internal parameter changes, the ideal current model is designed as a transfer function:

[0039]

[0040] where C is the output capacitance, i o is the output current of the dual active bridge voltage conversion unit, V o is the output voltage of the dual active bridge voltage conversion unit, represents the calculation delay, Δ Total (s) represents the uncertainty of the system, and f(s) represents the external disturbance;

[0041] Step 6: Based on the reconstructed linear model of the dual active bridge voltage conversion unit in step 4 and the ideal current model in step 5, the linear system of the UDE-based robust voltage control strategy, the reference value of the system state, and the tracking error convergence are obtained;

[0042] Step 6.1: The linear system of the UDE-based robust voltage control strategy is defined as:

[0043]

[0044] Where x(t) represents the system state, V(t) represents the input state of the system, A and B represent the known system state matrices that determine the closed-loop state of the system, ΔA represents the unknown state of the system, and f(t) represents the external disturbance;

[0045] Step 6.2: The control objective of the UDE is to eliminate external disturbances and uncertainties to ensure that the system state variable x(t) tracks its reference value x m (t), where the uncertainty and disturbance V d (t) The system under the controller can be expressed as:

[0046] V d (t)=ΔAx(t)+f(t)

[0047] The reference value of the system state is also expressed as:

[0048]

[0049] Among them A m and B m is the reference system state matrix, r(t) is the reference signal, when the system state variable x(t) tracks its reference value x well m (t), by choosing the system matrix A m and B m Determine the performance of the corresponding closed-loop system;

[0050] Step 6.3: Track x(t) to its reference value x m The tracking error of (t) is defined as: e(t)x m (txt)

[0051] The corresponding tracking error convergence rate is defined as:

[0052]

[0053] Where K is the state feedback gain; based on The control input of the dual active bridge boost conversion unit should satisfy:

[0054] V(t)=B + [A m x(t)-Ax(t)+B m r(t)-V d (t)]

[0055] Among them B + represents the pseudo-inverse of the system state matrix B;

[0056] Step 7: Based on the uncertainty and disturbance V of the linear system d (t), an estimated value V is introduced here de (t) replaces the uncertainty of the system and the external disturbance value, and the disturbance estimator is expressed in the time domain as:

[0057] V de (t) = g f (t)*V d (t) = L -1 {G f (s)[sx(s)-Ax(s)-Bu(s)]}

[0058] Among them, V de (t) is V d The estimated value of (t), g f (t) represents the filter G f (s) the strict impulse response, L -1 represents the Laplace operator, V de (t) in G f (s) within the bandwidth of V d (t); s represents the frequency domain, and x(s) is the frequency domain representation of x(t);

[0059] Step 8: Based on the time domain representation of the disturbance estimator proposed in Step 7, the state system reference is defined as:

[0060]

[0061] Wherein, α represents the closed-loop bandwidth of the dual-active bridge boost converter unit, satisfying α>0;

[0062] The voltage tracking error at this time is expressed as:

[0063] e(t)=V m (t)-V o (t)

[0064] Its dynamic characteristics should meet the following requirements:

[0065]

[0066] It can be seen that the convergence speed of the tracking error is determined by α+k;

[0067] Step 9: Based on the robust voltage linear system of the UDE and the dynamic model of the dual active bridge boost converter unit, the corresponding control law is obtained; when the system disturbance does not disappear, a disturbance estimation filter is designed;

[0068] Step 9.1: The corresponding control law is:

[0069] m ref (t) = m fb (t)-f e (t)

[0070] Among them, m fb (t) is the state feedback quantity, f e (t) represents the estimated value of the external disturbance f(t), which is expressed as:

[0071] m fb (t) = αC[V ref (t)-V o (t)+ke(t)]+i o (t)

[0072]

[0073] Among them, T s represents the sampling time of the UDE-based robust voltage controller; is the reference output voltage of the dual active bridge boost conversion unit;

[0074] Step 9.2: If the time delay cannot be determined, the system uncertainty and disturbance will disappear, and the state feedback m fb (t) Achieve tracking performance; when the disturbance does not disappear, the disturbance estimation filter is designed as:

[0075] G f (s) = β / (s + β)

[0076] The disturbance within the bandwidth β is estimated by using a disturbance filter. Once the controller parameters of closed-loop bandwidth α, tracking convergence speed k, and disturbance rejection bandwidth β are set, the UDE-based robust controller controls the dual-active bridge boost converter unit and responds to external disturbances.

[0077] Step 10: Based on the control law obtained in Step 9 and the designed disturbance estimation filter, when the power output port is connected to a constant power load, the relationship between voltage and current in the device circuit changes in the opposite direction. At this time, the incremental impedance caused by the constant power load is expressed as:

[0078] ΔR=-V o / I o

[0079] According to the incremental impedance, the equivalent output impedance Z of the constant power load is obtained s , specifically:

[0080] According to the dynamic model of the dual-active bridge boost converter unit and the control law of the robust voltage controller based on UDE, the ideal voltage source is expressed as:

[0081]

[0082] Output impedance Z s Expressed as:

[0083]

[0084] The corresponding output voltage V o for:

[0085]

[0086] When the device circuit meets:

[0087] ||Z s (z) / Z L (z)|| ∞ <1

[0088] At this time, the device circuit maintains a stable state. When the design of the control parameters meets the following conditions, the circuit is stably controlled, that is, 1 / (zG s The roots of (z)+α+k) are inside the unit circle;

[0089] Step 11: Based on the control law obtained in step 9, the closed-loop bandwidth α, error convergence speed k, and interference suppression bandwidth β are reasonably set according to the standards of electric vehicles, and the device circuit stability condition obtained in step 11 under the constant power mode is considered. Finally, the control signal is sent by the robust voltage controller based on UDE and transmitted to the IGBT drive module. The IGBT module converts the control signal of the robust voltage controller based on UDE into an IGBT drive signal, and performs switching control on the fully controlled devices, realizing the phase shift modulation of the dual active bridge boost conversion unit, and finally realizing the voltage gain process, with the voltage V out Output;

[0090] Step 12: The energy-consuming car that needs to be charged is directly connected to the power output port of the dual-active bridge boost conversion unit to obtain the voltage V after the battery pack of the energy-supplying electric vehicle is boosted and converted. out , and during the constant power charging process, due to the design of the controller, the circuit can maintain a stable output, so that the energy-consuming electric vehicle can obtain a stable input charging voltage;

[0091] In the constant power charging mode, the charging mode of the electric vehicle is the fast charging mode, which realizes efficient power sharing between electric vehicles.

[0092] The beneficial technical effects of the present invention are:

[0093] 1. According to the national standard "GB-T 20234.1-2015 Electric Vehicle Conductive Charging Connection Device," there are currently four types of electric vehicle charging modes. This invention utilizes the fourth type, commonly known as fast charging, also known as DC charging. Fast charging has a charging voltage of 200V-600V and a charging power of generally over 30kW. A five-minute charge can provide an electric vehicle with 10 kilometers of driving range, effectively meeting the rapid energy transfer requirements of electric vehicles.

[0094] 2. The circuit characteristics of the present invention are well adapted to the working state under high power and high voltage. Electric vehicles will obtain the maximum power supply in the shortest time and have the characteristics of high efficiency.

[0095] 3. Safe and reliable use. Due to differences in the models of the power supply and load electric vehicles, as well as the electronic components of the device itself, minor system disturbances are inevitable. The DAB circuit topology used in this invention has good symmetry, achieving ZVS switching on both the primary and secondary sides. It also has low current and voltage stress on the switching tubes and maintains good regulation performance within a range of large input voltage and load variations.

[0096] 4. Achieve the performance requirements of constant power, high current, and high gain. Compared with other DC converters, the present invention adopts a high-efficiency DAB circuit topology structure to avoid problems such as reactive power and ensure the acquisition of stable DC power supply energy. On this basis, if a high-frequency power transformer is added to the DAB circuit topology structure, the power density can be significantly improved to achieve the goals of high current and high gain. Moreover, the control strategy of the present invention fully considers the impact of the disturbance on the system stability. Therefore, the influence of the disturbance is eliminated through UDE, so that the overall output power can be maintained in a constant state, overcoming the power instability caused by the system disturbance.

[0097] 5. Compared to the Quasar device, this invention achieves breakthroughs in portability and affordability. Its DAB circuit topology and layered control assembly significantly reduce the use of capacitors, resistors, and other components, effectively reducing the device's weight and size, and significantly lowering production costs. The device can be carried by an adult. Furthermore, it enables bidirectional energy transfer between different electric vehicles, making it suitable for vehicle-to-vehicle energy sharing scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Figure 1 An operating mode diagram of an electric vehicle power mutual aid device based on a constant power charging mode according to an embodiment of the present invention;

[0099] Figure 2 A diagram of the charging output mode of an embodiment of the present invention;

[0100] Figure 3 The embodiment of the application provides energy for electric vehicle battery Thevenin equivalent;

[0101] Figure 4 The embodiment of the application Boost step-up conversion unit;

[0102] Figure 5 The embodiment of the application is a dual active bridge step-up conversion unit under phase shift control;

[0103] Figure 6 The embodiment of the application is a dynamic model of output current of the dual active bridge step-up conversion unit;

[0104] Figure 7 The embodiment of the application is a whole control chart;

[0105] Figure 8 The embodiment of the application is a working flow chart of the electric vehicle power interconnection device under constant power mode;

[0106] Figure 9 The embodiment of the application is a constant power load output impedance chart. DETAILED DESCRIPTION

[0107] The application will be further described below in combination with the drawings and embodiments;

[0108] The purpose of the application is to provide an electric vehicle power interconnection device based on constant power charging mode and a control method thereof, which meets the fast charging standard of electric vehicles. Through the DAB hardware topology and the robust voltage control strategy based on UDE, the electric quantity interconnection between vehicles is realized, a new charging method is provided for the charging difficulty and range anxiety problem of long-distance driving of electric vehicles caused by the lack of charging piles in remote areas under the background of double carbon target and the booming development of electric vehicles, thereby effectively alleviating the range anxiety problem hindering the development of electric vehicles, improving the enthusiasm of consumers to purchase electric vehicles, promoting the development of electric vehicles, and at the same time, this is also an effective practice of the concept of energy "sharing", which is highly consistent with the distribution and interaction concept of new power systems, and promotes the popularization of new energy. In addition, the device has the characteristics of high efficiency, portability, safety, economy and the like, which will help to realize industrialization, large-scale and application production in the electric vehicle industry, stimulate the demand for power batteries, become the key to consume a large amount of renewable energy, and then promote the popularization of green energy.

[0109] As Figure 1As shown, the present invention provides an electric vehicle power mutual aid device in constant power mode with portable, economical and high-gain characteristics, comprising: a battery unit, a Boost boost conversion unit, a dual active bridge boost conversion unit, a voltage / current sensor, an A / D module, an IGBT drive module, and a robust voltage controller based on UDE;

[0110] Its working mode is based on the electric vehicle power mutual aid device based on the constant power charging mode. The electric vehicle with sufficient power provides electric energy to the electric vehicle with less power that needs power input through the electric vehicle power mutual aid device based on the constant power charging mode. Its charging output mode is as follows: Figure 2 shown.

[0111] The electric vehicle with sufficient power provides a battery unit as the access power source for the device. The battery unit is the battery pack of the electric vehicle, which is generally composed of 4 to 6 groups of 12V batteries, that is, the output voltage is about 48 to 72V. Figure 3 After the Thevenin equivalent shown, the battery unit provides a voltage V to the Boost conversion unit. dc , the Boost conversion unit consists of an input capacitor, an inductor, a set of complementary conducting switches and diodes, and an output capacitor, such as Figure 4 As shown, V dc Under the boosting effect of the Boost boost conversion circuit, V dc Achieve V in The local boost is then used as the input voltage of the dual active bridge boost conversion unit through the power input port, as shown in Figure 5 The figure shows a dual-active bridge boost conversion unit under phase-shift control. The dual-active bridge boost conversion unit is composed of two symmetrical H-bridges on the primary and secondary sides, a path inductor L, an output side capacitor C, and a high-frequency transformer isolating the primary and secondary side bridges. The transformer has a transformation ratio of 1:n, and its primary and secondary sides have good symmetry, which is easy to implement soft switching. The power transmission of the conversion unit can be achieved by adjusting the phase shift between the primary side square wave voltage and the secondary side square wave voltage. The two symmetrical H-bridges on the primary and secondary sides are composed of control power devices Q1 to Q8. The Q1 to Q4 are connected in parallel with the path inductor L, and the path inductor L is also connected in parallel with the control power devices Q5 to Q8 and the output side capacitor C. They are connected in parallel with the high-frequency transformer isolating the primary and secondary side bridges. The circuit structure and modulation method of the dual-active bridge boost conversion unit are obtained. Figure 6 The current output mode is shown in the figure. The input voltage is Figure 7 The boost effect of the dual active bridge boost converter unit under the robust voltage control strategy based on UDE is shown to achieve the input voltage from V in to V oThe final output voltage is the rated voltage V of the electric vehicle to be charged through the power output port to the energy-consuming electric vehicle with insufficient power. out , in constant power charging mode, it can achieve a charging process of 10 kilometers of driving in 5 minutes.

[0112] The Boost conversion unit has an input end connected to the battery of the energy vehicle through an electrical clamp, and an output end directly connected to the dual-active bridge boost conversion unit; the battery is input to the Boost conversion unit after the Thevenin equivalent voltage V dc , after the preliminary boost conversion of the Boost boost conversion unit, the gain voltage from the battery unit is input to the dual-active bridge boost conversion unit; the dual-active bridge boost conversion unit has an input end connected to the Boost boost conversion unit and an output end connected to the load vehicle; after the boost conversion, it provides a charging interface in a constant power mode for an electric vehicle with insufficient power; the voltage / current sensor has an input end connected to the dual-active bridge boost conversion unit and an output end connected to the A / D module; it is used to collect the voltage and current of the power output port of the dual-active bridge boost conversion unit; the A / D module has an input end connected to the voltage / current sensor and an output end connected to a robust voltage controller based on UDE; it is used to collect the voltage and current of the power output port of the dual-active bridge boost conversion unit The voltage and current analog signals of the power output port are converted into digital signals and transmitted to the UDE-based robust voltage controller; the UDE-based robust voltage controller has an input end connected to the A / D module and an output end connected to the IGBT driver module; it controls according to the voltage and current digital signals of the power output port and sends the control signal to the IGBT driver module; the IGBT driver module has an input end connected to the UDE-based robust voltage controller and an output end connected to the dual-active bridge-type boost conversion unit; it converts the IGBT drive signal according to the control signal of the UDE-based robust voltage controller and sends the IGBT drive signal to the dual-active bridge-type boost conversion unit for controlling the dual-active bridge-type boost conversion unit;

[0113] On the other hand, a control method for an electric vehicle power mutual aid device in a constant power mode is shown in the overall control diagram. Figure 7 As shown in the working diagram of the device Figure 8 As shown, the specific steps include:

[0114] Step 1: Connect the battery voltage of the energy-supplying electric vehicle to the Boost converter circuit through the power wire and the positive and negative polarity electric clamps, and connect the energy-consuming vehicle directly to the power output port of the dual-active bridge boost converter circuit through the charging port; Figure 2The vehicle-mounted battery is powered by a weak power supply, and the weak power supply is equivalent to a Thevenin equivalent circuit of a series inductance of the power supply; wherein the equivalent inductance L = 1 / SCR [p.u.], and the SCR is referred to as a minimum short-circuit ratio, which is commonly used to characterize the strength of the power grid. According to the IEEE1204-1997 standard, when the SCR is 2-3, the system belongs to a weak power grid system. The minimum short-circuit ratio of a common DC charging pile of an electric vehicle can reach SCR>20. Therefore, it belongs to a weak power supply input system, and the voltage of the final boost voltage conversion unit is equivalent to the input voltage V dc , and the input current is i u ; the boost voltage conversion unit is as shown in Figure 4 ;

[0115] Step 2: The battery unit transmits the equivalent voltage signal to the boost voltage conversion unit, and the input voltage V dc is locally boosted by the boost voltage conversion unit, and the voltage V in is output.

[0116] A generalized average model of the Thevenin equivalent impedance is used to establish a model of the boost voltage conversion unit, as shown in Figure 3 , and the average modeling is as shown below:

[0117]

[0118]

[0119] wherein u u represents the duty ratio in the boost circuit, ΔL gu represents the Thevenin equivalent inductance value, L u represents the inductance in the boost circuit, ΔC u represents the capacitance uncertainty value caused by the parasitic capacitance; V in is the output voltage of the boost circuit, C u is the output capacitance of the boost circuit, V dc represents the input voltage of the battery unit connected to the boost circuit, i u is the path current of the boost circuit, and i in is the output current of the boost circuit.

[0120] Step 3: Based on the locally boosted signal V in obtained in step 2, a voltage high-gain dual active bridge voltage conversion unit is connected through an electric energy input port; the dual active bridge voltage conversion unit collects the voltage value after the initial boost of the boost circuit through the electric energy input port, and stably boosts and converts the input voltage by changing the transformer ratio; as shown in Figure 5FIG. 1 is a schematic diagram of a dual-active bridge-type boost converter unit using a phase-shift control scheme;

[0121] Where V in represents the input voltage of the dual-active bridge boost converter unit, Q1 to Q8 represent fully controlled power devices, C represents the output capacitor, L represents the leakage inductance of the transformer, V o Represents the output voltage of the dual active bridge boost converter unit, V ref Indicates V o Tracking reference voltage, i o Represents the output current of the dual active bridge boost converter unit.

[0122] When the dual-active bridge boost conversion unit uses a single-phase shift SPS to modulate the internal transformer of the dual-active bridge boost conversion unit, if F s is the switching frequency, D is the phase shift angle, and the fixed duty cycle is 50%. At this time, the transfer power of the input port and output port of the dual active bridge boost conversion unit is:

[0123]

[0124] Where V in represents the input voltage of the dual active bridge boost converter unit, L represents the inductance of the transformer, V o represents the output voltage of the dual-active bridge boost conversion unit; n represents the transformation ratio of the transformer;

[0125] By modulating the corresponding transformer ratio, the input voltage V in Reach the rated voltage V required for charging electric vehicles out ;

[0126] Step 4: Based on the phase-shift modulation strategy and boost process described in step 3, the circuit structure and phase-shift modulation method of the DAB boost conversion unit are integrated and reconstructed by integrating the circuit structure of the dual-active bridge boost conversion unit to obtain the dynamic current model of the dual-active bridge boost conversion unit, which provides a general linear model for the robust voltage controller based on UDE; Figure 6 As shown, where u ref Indicates the output voltage u o Tracking reference voltage, m represents the output current of the dual active bridge boost converter unit, which is composed of the output capacitor current i c and the output port current i o composition.

[0127] The general linear model is given by UDE for the output voltage V o Tracking reference voltage V ref Perform collection and calculation to obtain the corresponding current tracking value m refThe current tracking quantity is used as the input of the dual-active bridge boost conversion unit. The control quantity is obtained by performing time delay calculation and phase conversion on the current tracking quantity to drive the dual-active bridge boost conversion unit to work. The dual-active bridge boost conversion circuit outputs a dynamic current m. This current is a dynamically changing current and therefore a dynamic linear model. m is finally decomposed into the current i passing through the output capacitor of the dual-active bridge boost conversion unit. c and the output port current i of the dual active bridge boost converter unit o ,i o It is returned to the UDE-based robust voltage controller as a closed-loop input;

[0128] The UDE-based robust voltage controller initializes the output voltage V of the dual active bridge boost converter unit. o The dynamic output current m is obtained through the dual active bridge boost conversion unit circuit structure and phase shift modulation strategy, and then the estimated value of the output current m is obtained through the disturbance estimator. ref , the estimated value m ref The input is fed into the robust voltage controller to obtain the actual controller component, thereby obtaining the control signal of the IGBT drive module, and finally driving the dual active bridge boost converter unit to work;

[0129] The specific operation includes initializing the output voltage, and the output voltage obtained by initialization according to Kirchhoff's law is:

[0130] V out =V o -V in

[0131] Among them, V o is the output voltage of the dual active bridge boost converter unit, V out is the actual charging input voltage of the final electric vehicle, V in The output voltage of the Boost circuit is also used as the input voltage of the dual active bridge boost conversion unit;

[0132] When the robust voltage control of UDE is adopted and the power output characteristics of the SPS solution are used, the dynamic current model of the dual active bridge boost converter unit is rewritten as:

[0133]

[0134]

[0135] Wherein, C is the output capacitance of the dual active bridge boost converter unit;

[0136] At this time, a specific current m is generated ref The phase shift angle is:

[0137]

[0138] Step 5: Based on the dynamic current model of the dual-active bridge boost converter unit reconstructed in Step 4, the voltage / current sensor converts the output current m of the dual-active bridge dual-boost converter unit into a digital signal and transmits it as input to the UDE-based robust voltage controller. That is, the UDE-based robust voltage controller is designed based on the current model of the dual-active bridge boost converter unit. In this case, if the output of the robust controller is directly designed as a phase shift angle, the controller will lose its universality. However, since the current model is the same, the current-oriented controller design concept can simplify the controller design. In this case, the current tracking error caused by the phase shift angle D should be taken into account in the controller design to compensate for the system uncertainty and voltage tracking error. Taking into account the uncertainties brought about by system characteristics, external disturbances, and internal parameter changes, the ideal current model is designed as the transfer function:

[0139]

[0140] Where C is the output capacitance, i o is the output current of the dual active bridge boost converter unit, V o is the output voltage of the dual active bridge boost converter unit, represents the computation delay, Δ Total (s) represents the uncertainty of the system, f(s) represents the external disturbance;

[0141] Based on the external disturbance and uncertainty of internal circuit parameters in the process of realizing voltage gain, the stability of the output signal of the present invention is bound to be affected. In practical applications, in order to avoid interference between the two switches of the same-phase bridge arm and thus cause distortion of the output voltage, and change the transmission characteristics of the dual-active bridge boost conversion unit, the present invention regards the nonlinearity caused by the dead zone effect as the uncertainty of the system. Based on this, the control strategy adopted by the present invention is the control of the mixed domain (DRC) scheme based on the disturbance observer, in which the UDE uses the time domain model and state measurement value to realize feedback control and interference estimation, and uses the frequency domain filter to make the control law causal.

[0142] Step 6: Based on the reconstructed linear model of the dual active bridge boost converter unit in step 4 and the ideal current model in step 5, the linear system of the robust voltage control strategy of the UDE, the reference value of the system state, and the tracking error convergence are obtained;

[0143] Step 6.1: The linear system of the robust voltage control strategy of the UDE is defined as:

[0144]

[0145] Where x(t) represents the system state, V(t) represents the input state of the system, A and B represent the known system state matrices that determine the closed-loop state of the system, ΔA represents the unknown state of the system, and f(t) represents the external disturbance;

[0146] Step 6.2: The control objective of the UDE is to eliminate external disturbances and uncertainties to ensure that the system state variable x(t) tracks its reference value x m (t), where the uncertainty and disturbance V d (t) The system under the controller can be expressed as:

[0147] V d (t)=ΔAx(t)+f(t)

[0148] The reference value of the system state is also expressed as:

[0149]

[0150] Among them A m and B m is the reference system state matrix, r(t) is the reference signal, when the system state variable x(t) tracks its reference value x well m (t), by choosing the system matrix A m and B m Determine the performance of the corresponding closed-loop system;

[0151] Step 6.3: Track x(t) to its reference value x m The tracking error of (t) is defined as: e(t)x m (txt)

[0152] The corresponding tracking error convergence rate is defined as:

[0153]

[0154] Where K is the state feedback gain; based on The control input of the dual active bridge boost conversion unit should satisfy:

[0155] V(t)=B + [A m x(t)-Ax(t)+B m r(t)-V d (t)]

[0156] Among them B + represents the pseudo-inverse of the system state matrix B;

[0157] Step 7: Based on the uncertainty and disturbance V of the linear system d(t), an estimated value V is introduced here de (t) replaces the uncertainty of the system and the external disturbance value, and the disturbance estimator is expressed in the time domain as:

[0158] V de (t) = g f (t)*V d (t) = L -1 {G f (s)[sx(s)-Ax(s)-Bu(s)]}

[0159] Among them, V de (t) is V d The estimated value of (t), g f (t) represents the filter G f (s) the strict impulse response, L -1 represents the Laplace operator, V de (t) in G f (s) within the bandwidth of V d (t); s represents the frequency domain, and x(s) is the frequency domain representation of x(t);

[0160] Step 8: Based on the time domain representation of the disturbance estimator proposed in Step 7, the state system reference is defined as:

[0161]

[0162] Wherein, α represents the closed-loop bandwidth of the dual-active bridge boost converter unit, satisfying α>0;

[0163] The voltage tracking error at this time is expressed as:

[0164] e(t)=V m (t)-V o (t)

[0165] Its dynamic characteristics should meet the following requirements:

[0166]

[0167] It can be seen that the convergence speed of the tracking error is determined by α+k;

[0168] Step 9: Based on the robust voltage linear system of the UDE and the dynamic model of the dual active bridge boost converter unit, the corresponding control law is obtained; when the system disturbance does not disappear, a disturbance estimation filter is designed;

[0169] Step 9.1: The corresponding control law is:

[0170] m ref (t) = m fb (t)-f e(t)

[0171] Among them, m fb (t) is the state feedback quantity, f e (t) represents the estimated value of the external disturbance f(t), which is expressed as:

[0172] m fb (t) = αC[V ref (t)-V o (t)+ke(t)]+i o (t)

[0173]

[0174] Among them, T s represents the sampling time of the UDE-based robust voltage controller; is the reference output voltage of the dual active bridge boost conversion unit;

[0175] Step 9.2: If the time delay cannot be determined, the system uncertainty and disturbance will disappear, and the state feedback m fb (t) Achieve tracking performance; when the disturbance does not disappear, the disturbance estimation filter is designed as:

[0176] G f (s) = β / (s + β)

[0177] The disturbance within the bandwidth β is estimated by using a disturbance filter. Once the controller parameters of closed-loop bandwidth α, tracking convergence speed k, and disturbance rejection bandwidth β are set, the UDE-based robust controller controls the dual-active bridge boost converter unit and responds to external disturbances.

[0178] Step 10: Based on the control law obtained in Step 9 and the designed disturbance estimation filter, when the power output port is connected to a constant power load, the relationship between voltage and current in the device circuit changes in the opposite direction. At this time, the incremental impedance caused by the constant power load is expressed as:

[0179] ΔR=-V o / I o

[0180] According to the incremental impedance, the constant power load is obtained as follows Figure 9 The equivalent output impedance Z shown s , where V s The ideal voltage source representing the output voltage of the dual active bridge boost converter unit under no-load conditions, Z s Represents the output impedance of the dual active bridge boost converter unit, Z L Indicates constant power load, V oIndicates the output voltage of the equivalent output to the constant power load, i o Indicates the equivalent output current.

[0181] According to the dynamic model of the dual-active bridge-type boost converter unit and the control law of the robust voltage controller of the disturbance estimator, the ideal voltage source is expressed as:

[0182]

[0183] Output impedance Z s Expressed as:

[0184]

[0185] The corresponding output voltage V o for:

[0186]

[0187] When the device circuit meets:

[0188] ||Z s (z) / Z L (z)|| ∞ <1

[0189] When we design the control parameters, considering that the input voltage of the charging car is 200-600V and the input power is about 30KW, the circuit can be stably controlled if the control parameters meet the following conditions:

[0190] At this time, the device circuit maintains a stable state. When the design of the control parameters meets the following conditions, the circuit is stably controlled, that is, 1 / (zG s The roots of (z)+α+k) are inside the unit circle;

[0191] Step 11: Based on the control law obtained in step 9, the closed-loop bandwidth α, error convergence speed k, and interference suppression bandwidth β are reasonably set according to the standards of electric vehicles, and the device circuit stability condition obtained in step 11 under the constant power mode is considered. Finally, the control signal is sent by the robust voltage controller based on UDE and transmitted to the IGBT drive module. The IGBT module converts the control signal of the robust voltage controller based on UDE into an IGBT drive signal, and performs switching control on the fully controlled devices, realizing the phase shift modulation of the dual active bridge boost conversion unit, and finally realizing the voltage gain process, with the voltage V out Output;

[0192] Step 12: The energy-consuming car that needs to be charged is directly connected to the power output port of the dual-active bridge boost conversion unit to obtain the voltage V after the battery pack of the energy-supplying electric vehicle is boosted and converted. out, and during the constant power charging process, due to the design of the controller, the circuit can maintain a stable output, so that the energy-consuming electric vehicle can obtain a stable input charging voltage;

[0193] In the constant power charging mode, the electric vehicle is charged in a fast charging mode, which enables efficient power sharing between electric vehicles. The overall flow chart is as follows: Figure 8 shown.

[0194] This invention innovatively proposes vehicle-to-vehicle energy sharing, exploring an alternative energy supply solution for emergency situations based on the limited battery capacity and inadequate supporting infrastructure of current electric vehicles. By overcoming the limitations of traditional power supplies, the invention utilizes alternative, more robust electric vehicles to provide energy, providing a practical and feasible emergency energy supply solution.

[0195] The present invention adopts a dual-active bridge-type boost converter circuit topology. According to the relevant provisions of the national standard and the current industrial status, the present invention needs to meet the requirements of constant power and high gain, and must be a DC converter. This topology has good symmetry and is widely used in new energy fields such as hybrid vehicles, battery energy storage, supercapacitor charging, UPS uninterruptible power supply systems and solar power generation. The input voltage is controlled by the boosting effect and control strategy of the Boost boost conversion unit and the dual-active bridge-type boost conversion unit, and finally outputs a constant power that meets the electric vehicle fast charging standard and outputs an output voltage that meets the rated input voltage standard, which can meet the relevant requirements of the present invention for power and voltage.

[0196] The robust voltage control strategy based on a disturbance observer adopted by the present invention comprehensively considers system uncertainty caused by the uncertainty of the energy supply / energy consumption vehicle type, external interference, load characteristics such as dead zone effects, calculation time delays, circuit parameter uncertainty, and constant power load (constant power), thereby effectively reducing the tracking error of the dual-active bridge boost converter circuit and improving the stability and output performance of the output voltage.

[0197] The present invention establishes a dynamic model by modeling the output current model of the dual-active bridge boost converter circuit, which will provide a linear control law under the constant power mode for the control strategy, greatly reducing the computational burden of the digital processor, providing support for our selection of a digital processor with limited but economical computing power, and has the advantages of simple controller design and low computational burden of the control algorithm.

[0198] This paper derives the output impedance of a dual-active bridge-type boost converter unit under robust voltage control based on a disturbance observer to demonstrate the stability boundary of the dual-active bridge-type boost converter unit when connected to a constant-power load. This ensures that the output signal is stable during constant-power charging.

Claims

1. A method for controlling electric vehicle power mutual assistance in constant power mode, characterized in that: The following steps are involved: Step 1: Connect the battery voltage of the energy-supplying electric vehicle to the Boost converter circuit through a powered wire and an electrical clamp with positive and negative polarity, and connect the energy-consuming vehicle directly to the power output port of the dual-active bridge boost converter circuit through the charging port; the on-board battery power supply is a weak power supply, and the weak power supply is equivalent to the Thevenin equivalent circuit of the power supply series inductor; the equivalent inductance L = 1 / SCR [p.u.], SCR is called the minimum short-circuit ratio, which is often used to characterize the strength of the power grid and belongs to a weak power input system. Finally, the boost converter unit voltage is equivalent to the input voltage , the input current is ; Step 2: The battery unit transmits its equivalent voltage signal to the Boost conversion unit, and the input voltage After passing through the Boost conversion unit, a local boost will be performed to voltage is the output of the Boost circuit; The Boost converter unit is modeled using the generalized average model of Thevenin equivalent impedance. The average modeling is shown below: ； ； in, Represents the duty cycle in the Boost circuit, represents the Thevenin equivalent inductance value, Represents the path inductance in the Boost circuit, Indicates the capacitance uncertainty value caused by parasitic capacitance; is the output voltage of the Boost circuit, is the output capacitance of the Boost circuit, Indicates the input voltage of the battery unit connected to the Boost circuit. is the path current of the Boost circuit, is the output current of the Boost circuit; Step 3: Output voltage of the Boost circuit based on the output voltage obtained in step 2 , accessing a high-voltage-gain dual-active bridge-type boost conversion unit through the power input port; the dual-active bridge-type boost conversion unit collects the voltage value after the initial boost of the Boost circuit through the power input port, and performs a stable boost conversion on the input voltage by changing the transformation ratio of the internal transformer; When the dual-active bridge boost conversion unit uses a single-phase shift SPS to modulate the internal transformer of the dual-active bridge boost conversion unit, if is the switching frequency, D is the phase shift angle, and the fixed duty cycle is 50%. At this time, the transfer power of the input port and output port of the dual active bridge boost conversion unit is: ； in Represents the input voltage of the dual active bridge boost converter unit, that is The output voltage of the Boost circuit is also the input voltage of the dual active bridge boost conversion unit. represents the inductance of the transformer, represents the output voltage of the dual-active bridge boost conversion unit; n represents the transformation ratio of the transformer; By modulating the corresponding transformer ratio, the input voltage Reach the rated voltage required for electric vehicle charging ; Step 4: Based on the single-phase shifted SPS and boost process in step 3, the circuit structure and phase shift modulation method of the DAB boost conversion unit are integrated and reconstructed by integrating the circuit structure of the dual-active bridge boost conversion unit to obtain the dynamic current model of the dual-active bridge boost conversion unit; The dynamic current model of the dual active bridge boost converter unit is used to calculate the output voltage through UDE. Tracking reference voltage Collect and calculate to get the estimated value of the corresponding output current The estimated value of the output current is used as the input of the dual-active bridge boost conversion unit. The control quantity is obtained by performing time delay calculation and phase conversion on the current tracking quantity to drive the dual-active bridge boost conversion unit to work. The dual-active bridge boost conversion circuit outputs a dynamic current , the current is a dynamically changing current, so the model is a dynamic linear model, Finally, it is decomposed into the current through the output capacitor of the dual active bridge boost converter unit and the output port current of the dual active bridge boost converter unit , It is returned to the UDE-based robust voltage controller as a closed-loop input; Step 5: Based on the dynamic current model of the dual-active bridge boost converter unit reconstructed in step 4, the voltage / current sensor converts the output current of the dual-active bridge dual-boost converter unit to Converted into a digital signal and passed as input to the UDE-based robust voltage controller; that is, the UDE-based robust voltage controller is designed according to the current model of the dual-active bridge boost converter unit. At this time, if the output of the robust controller is directly designed as a phase shift angle, the controller will lose its versatility. However, since the current model is the same, the current-oriented controller design concept can simplify the controller design. At this time, the phase shift angle The resulting current tracking error should be taken into account in the controller design to compensate for the system uncertainty and voltage tracking error. Taking into account the uncertainties brought about by system characteristics, external disturbances, and internal parameter changes, the ideal current model is designed as a transfer function; Step 6: Based on the reconstructed linear model of the dual active bridge boost converter unit in step 4 and the ideal current model in step 5, the linear system of the robust voltage control strategy of the UDE, the reference value of the system state, and the tracking error convergence are obtained; Step 7: Uncertainty and disturbance based on linear system , an estimated value is introduced here Instead of the uncertainty of the system and the external disturbance value, the disturbance estimate is expressed in the time domain; Step 8: Based on the time domain representation of the disturbance estimator proposed in step 7, redefine the state system reference value; Step 9: Based on the robust voltage linear system of the UDE and the dynamic model of the dual active bridge boost converter unit, the corresponding control law is obtained; when the system disturbance does not disappear, a disturbance estimation filter is designed; Step 10: Based on the control law obtained in step 9 and the designed disturbance estimation filter, when the power output port is connected to a constant power load, the relationship between the voltage and current in the device circuit changes in the opposite direction, and finally the condition for the device circuit to remain stable is obtained; Step 11: Based on the control law obtained in step 9, reasonably set the closed-loop bandwidth according to the standards of electric vehicles , error convergence speed , interference suppression bandwidth , and considering the device circuit stability conditions obtained in constant power mode, the control signal is finally sent by the robust voltage controller based on UDE and transmitted to the IGBT drive module. The IGBT module converts the control signal of the robust voltage controller based on UDE into an IGBT drive signal, and performs switch control on the fully controlled devices, realizing the phase shift modulation of the dual active bridge boost conversion unit, and finally realizing the voltage gain process, with voltage Output; Step 12: The energy-consuming car that needs to be charged is directly connected to the power output port of the dual-active bridge boost conversion unit to obtain the voltage after the boost conversion of the battery pack of the energy-supplying electric vehicle. , and during the constant power charging process, due to the design of the controller, the circuit can maintain a stable output, so that the energy-consuming electric vehicle can obtain a stable input charging voltage; In the constant power charging mode, the electric vehicle is charged in a fast charging mode, which enables efficient power sharing between electric vehicles. The electric vehicle power mutual assistance control method under constant power mode realizes power mutual assistance based on the electric vehicle power mutual assistance device under constant power mode, which specifically includes: a battery unit, a Boost boost conversion unit, a dual active bridge boost conversion unit, a voltage / current sensor, an A / D module, an IGBT drive module, and a robust voltage controller based on UDE; The Boost conversion unit has an input end connected to the battery of the energy supply vehicle and an output end connected to the dual-active bridge-type boost unit; the dual-active bridge-type boost conversion unit has an input end connected to the Boost conversion unit and an output end connected to the load vehicle; the voltage / current sensor has an input end connected to the dual-active bridge-type boost conversion unit and an output end connected to the A / D module; the A / D module has an input end connected to the voltage / current sensor and an output end connected to the UDE-based robust voltage controller; the UDE-based robust voltage controller has an input end connected to the A / D module and an output end connected to the IGBT driver module; the IGBT driver module has an input end connected to the UDE-based robust voltage controller and an output end connected to the dual-active bridge-type boost conversion unit.

2. The electric vehicle power mutual assistance control method in constant power mode according to claim 1, characterized in that: The dual-active bridge-type boost conversion unit is composed of two symmetrical H-bridges on the primary and secondary sides, a path inductor L, an output-side capacitor C, and a high-frequency transformer that isolates the primary and secondary bridges. The transformer has a transformation ratio of 1:n. The two symmetrical H-bridges on the primary and secondary sides are composed of fully-controlled power devices Q1 to Q8. Q1 to Q4 are connected in parallel with the path inductor L, which is also connected in parallel with the fully-controlled power devices Q5 to Q8 and the output-side capacitor C. All of these are connected in parallel with the high-frequency transformer that isolates the primary and secondary bridges.

3. The electric vehicle power mutual assistance control method in constant power mode according to claim 2, characterized in that: In step 4, the UDE-based robust voltage controller initializes the output voltage of the dual active bridge boost converter unit. , dynamic output current is obtained through dual active bridge boost conversion unit circuit structure and phase shift modulation strategy , and then the estimated value of the output current is obtained through the disturbance estimator , the estimated value of the output current The input is fed into the robust voltage controller to obtain the actual controller component, thereby obtaining the control signal of the IGBT drive module, and finally driving the dual active bridge boost converter unit to work; The specific operations include: initializing the output voltage of the dual active bridge boost conversion unit , the output voltage is initialized according to Kirchhoff's law: ； in, is the output voltage of the dual active bridge boost converter unit, The actual charging input voltage for the final electric vehicle; When the robust voltage control of UDE is adopted and the power output characteristics of the SPS solution are used, the dynamic current model of the dual active bridge boost converter unit is rewritten as: ； ； Wherein, C is the output capacitance of the dual active bridge boost converter unit; The estimated output current at this time is The phase shift angle is: 。 4. The electric vehicle power mutual assistance control method in constant power mode according to claim 3, characterized in that: The ideal current model in step 5 is designed to have a transfer function as follows: ； in is the output capacitance, is the output current of the dual active bridge boost converter unit, is the output voltage of the dual active bridge boost converter unit, represents the computation delay, represents the uncertainty of the system, Indicates external interference.

5. The electric vehicle power mutual assistance control method in constant power mode according to claim 4, characterized in that: Step 6 is as follows: Step 6.1: The linear system of the robust voltage control strategy based on UDE is defined as: (t)=( A+ ) (t) +BV(t)+ f(t) in Indicates the system status, Represents the input state of the system, and represents the known system state matrix that determines the closed-loop state of the system, Indicates an unknown state of the system, Indicates external disturbance; Step 6.2: The control objective of the UDE is to eliminate external disturbances and uncertainties to ensure that the system state variables Track its reference value , where the uncertainty and disturbance The system under the controller is represented as: ； The reference value of the system state is also expressed as: = ； in and is the reference system state matrix, is the reference signal, when the system state variable Track its reference value By choosing the system matrix and Determine the performance of the corresponding closed-loop system; Step 6.3: Track its reference value The tracking error is defined as: ; The corresponding tracking error convergence rate is defined as: = + ； in, is the state feedback gain; based on (t), The control input of the dual active bridge boost conversion unit satisfies: ； in Represents the system state matrix Pseudo-reversal.

6. The electric vehicle power mutual assistance control method in constant power mode according to claim 5, characterized in that: The disturbance estimation in step 7 is expressed in the time domain as: ； in, yes The estimated value of Representation filtering The strict impulse response of represents the Laplace operator, exist Achieved within the bandwidth An estimate of ; s represents the frequency domain, and x(s) is the frequency domain representation of x(t).

7. The electric vehicle power mutual assistance control method in constant power mode according to claim 6, characterized in that: Step 8 Redefine the status system reference value as follows: = ； in, Represents the closed-loop bandwidth of the dual-active bridge boost converter unit, satisfying ; The voltage tracking error at this time is expressed as: ； Its dynamic characteristics should meet the following requirements: ； It can be seen that the tracking error convergence speed is given by Determined.

8. The electric vehicle power mutual assistance control method in constant power mode according to claim 7, characterized in that: Step 9 is as follows: Step 9.1: The corresponding control law is: ； in, is the state feedback quantity, Represents the external disturbance The estimated value of is expressed as: ； = +C ； in, represents the sampling time of the UDE-based robust voltage controller; is the reference output voltage of the dual active bridge boost conversion unit; Step 9.2: If the time delay cannot be determined, the system uncertainty and disturbance will disappear, and the state feedback To achieve tracking performance; when the disturbance does not disappear, the disturbance estimation filter is designed as: ； Bandwidth estimation via perturbation filter The disturbance amount within; when the controller parameter closed loop bandwidth , tracking convergence speed and disturbance rejection bandwidth After setting, the UDE-based robust voltage controller will control the dual-active bridge boost converter unit and respond to external disturbances.

9. The electric vehicle power mutual assistance control method in constant power mode according to claim 8, characterized in that: Step 10 is as follows: When the power output port is connected to a constant power load, the relationship between voltage and current in the device circuit changes in the opposite direction. At this time, the incremental impedance caused by the constant power load is expressed as: ； According to the incremental impedance, the equivalent output impedance of the constant power load is obtained , specifically: According to the dynamic model of the dual-active bridge-type boost converter unit and the control law of the robust voltage controller of the disturbance estimator, the ideal voltage source is expressed as: ； Output impedance Expressed as: ； The corresponding output voltage for: ； in, It is a constant power load; When the device circuit meets: ； At this time, the device circuit maintains a stable state. When the design of the control parameters meets the following conditions, the circuit is stably controlled, namely, The roots of are inside the unit circle.

Images