WO2022193343A1

WO2022193343A1 - Three-port bidirectional isolation converter and rail transit vehicle

Info

Publication number: WO2022193343A1
Application number: PCT/CN2021/082609
Authority: WO
Inventors: 周峰武; 张小勇; 刘金榕; 周帅; 饶沛南; 张庆; 曹金洲; 罗盼
Original assignee: 株洲中车时代电气股份有限公司
Priority date: 2021-03-16
Filing date: 2021-03-24
Publication date: 2022-09-22
Also published as: CN113014108A

Abstract

A three-port bidirectional isolation converter and a rail transit vehicle, comprising a control module and a converter circuit. The converter circuit comprises an inductor module and a dual active bridge converter circuit respectively connected to a first port, a second port, and a third port, and the inductor module and an input full-bridge converter module in the dual active bridge converter circuit constitutes two bidirectional buck-boost converter circuits which are connected in an interleaved parallel manner. In the present application, only one-stage DC/DC conversion is performed between any two ports, the conversion efficiency is high, the number of power switching devices, energy storage elements, filter elements and control elements is reduced, the power density is high, and the cost is low.

Description

A three-port bidirectional isolation converter and rail transit vehicle

This application claims the priority of the Chinese patent application filed on March 16, 2021 with the application number 202110281582.5 and the invention title "A three-port bidirectional isolation converter and rail transit vehicle", the entire contents of which are by reference Incorporated in this application.

technical field

The present application relates to the field of rail transit, in particular to a three-port bidirectional isolation converter and a rail transit vehicle.

Background technique

In systems with three ports of power supply bus, energy storage device, and load, such as new energy power generation, distributed power grid, and on-board energy storage two-way power supply, the traditional three-port two-way isolation converter structure is shown in Figure 1. Among them, the first The port V1 is used for connecting the power supply bus, the first port V2 is used for connecting the energy storage device, and the third port V3 is used for connecting the load. A non-isolated buck-boost converter is used for bidirectional conversion between the first port V1 and the second port V2, and a DAB (Dual Active Bridge) converter is used between the first port V1 and the third port V3. To achieve bidirectional isolation conversion, two-stage DC-DC conversion is performed between the second port V2 and the third port V3, that is, bidirectional conversion is realized by a buck-boost converter and a DAB converter successively, and the conversion efficiency is low. In addition, the above two DC/DC converters require independent power switching devices, energy storage components, filter components and control components, which reduces the power density and efficiency of the system, increases the number of components, and increases the system cost and control complexity. .

Therefore, how to provide a solution to the above technical problem is a problem that those skilled in the art need to solve at present.

SUMMARY OF THE INVENTION

The purpose of the present application is to provide a three-port bidirectional isolated converter and a rail transit vehicle, in which only one level of DC/DC conversion is performed between any two ports, and the conversion efficiency is high, while reducing power switching devices, energy storage elements, The number of filter elements and control elements, high power density and low cost.

In order to solve the above technical problems, the present application provides a three-port bidirectional isolation converter, which includes a control module and a conversion circuit, and the conversion circuit includes an inductance module and a dual port connected to the first port, the second port, and the third port respectively. an active bridge conversion circuit, wherein the inductance module and the input full-bridge conversion module in the dual active bridge conversion circuit form two interleaved parallel bidirectional buck-boost conversion circuits;

The control module is configured to control the first port and the second port to perform a corresponding bidirectional power conversion operation through the bidirectional buck-boost conversion circuit, and control the first port and the third port to pass through the bidirectional buck-boost conversion circuit. The dual active bridge conversion circuit performs a corresponding power bidirectional conversion operation, and the second port and the third port are controlled to perform a corresponding power bidirectional conversion operation through the dual active bridge conversion circuit.

Preferably, the input full-bridge conversion module includes a first filter capacitor, a second filter capacitor and a first full-bridge circuit, and the inductance module includes a first inductor and a second inductor, wherein:

The first end of the first filter capacitor is respectively connected to the negative electrode of the first port and the first end of the first full-bridge circuit, and the first end of the second filter capacitor is connected to the positive electrode of the second port and the first end of the first full bridge circuit. The second end of the first full-bridge circuit is connected, and the common end after the first filter capacitor and the second filter capacitor are connected are respectively connected to the negative electrode of the second port, the positive electrode of the first port, and the The first end of the first inductor is connected to the first end of the second inductor, the second end of the second inductor is connected to the third end of the first full-bridge circuit, and the first end of the first inductor is connected to the third end of the first full-bridge circuit. The two terminals are connected to the fourth terminal of the first full-bridge circuit.

Preferably, the first full-bridge circuit includes:

a first primary bridge arm composed of a first switch module and a second switch module;

a second primary bridge arm composed of a third switch module and a fourth switch module;

The common terminal of the first switch module and the second switch module is used as the third terminal of the first full-bridge circuit, and the common terminal of the third switch module and the fourth switch module is used as the first switch module. The fourth terminal of the full bridge circuit.

Preferably, the process of performing the corresponding bidirectional power conversion operation by the bidirectional buck-boost conversion circuit includes:

Output the corresponding pulse signal to the bidirectional buck-boost conversion circuit, when the first duty cycle of the pulse signal is less than 0.5, the bidirectional buck-boost conversion circuit performs a step-down operation, when the first duty cycle of the pulse signal is less than 0.5. When a duty cycle is greater than 0.5, the bidirectional buck-boost conversion circuit performs a boosting operation.

Preferably, the conversion circuit further includes an output full-bridge conversion module, a transformer and a resonant inductor, wherein:

The input full-bridge conversion module is respectively connected to the first port and the second port, the output full-bridge conversion module is connected to the third port, and the input full-bridge conversion module passes through the resonant inductance and The transformer is connected to the output full-bridge conversion module.

Preferably, the output full-bridge conversion module includes a second full-bridge circuit and a third filter capacitor, wherein:

The second full-bridge circuit is connected to the secondary side of the transformer, and the third filter capacitor is connected in parallel with the second full-bridge circuit.

Preferably, the second full-bridge circuit includes:

a first secondary side bridge arm composed of a fifth switch module and a sixth switch module;

The second secondary side bridge arm formed by the seventh switch module and the eighth switch module.

Preferably, the process of performing the corresponding bidirectional power conversion operation by the dual active bridge conversion circuit includes:

A phase shift control operation is performed on the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit.

Preferably, the process of performing a phase-shift control operation on the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit includes:

Inputting corresponding pulse signals to the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit respectively, the pulse signal corresponding to the input full-bridge conversion module and the output full-bridge conversion module The phase shift time between the corresponding pulse signals of the module is the product of the phase shift angle and the half switching period.

Preferably, the process of inputting the corresponding pulse signal to the output full-bridge transformation module includes:

The corresponding pulse signals are respectively input to the first secondary side bridge arm and the second secondary side bridge arm in the output full-bridge conversion module, and the pulse signal corresponding to the first secondary side bridge arm is ahead of the first secondary side bridge arm. The time of the pulse signal corresponding to the two secondary side bridge arms is the product of the second duty cycle and the switching period.

Preferably, the control module is also used for:

determining a voltage mode of the three-port bidirectional isolated converter;

The optimal operating point corresponding to each of the voltage modes is obtained, and the optimal operating point is the operating point that minimizes the return power of the three-port bidirectional isolated converter under the target output power.

Preferably, the process of obtaining the optimal operating point corresponding to each of the voltage modes includes:

The optimal operating point corresponding to each of the voltage modes is obtained by the Lagrange multiplier method.

Preferably, the process of obtaining the optimal operating point corresponding to each of the voltage modes by the Lagrangian multiplier method includes:

Obtain a plurality of operating points corresponding to each of the voltage modes by the Lagrangian multiplier method;

The operating point satisfying the boundary conditions of the voltage mode is determined as the optimal operating point.

In order to solve the above technical problems, the present application also provides a rail transit vehicle, including:

vehicle body;

A three-port bidirectional isolated converter as described in any of the above.

The present application provides a three-port bidirectional isolated converter, with only one level of DC/DC conversion between any two ports, high conversion efficiency, and multiplexing of the input full-bridge conversion module in the dual active bridge conversion circuit at the same time, Together with the inductance module, it forms two interleaved parallel bidirectional buck-boost conversion circuits, and the power conversion control between any two ports can be realized through one control module, reducing power switching devices, energy storage elements, filter elements and control. number of components, high power density and low cost. The present application also provides a rail transit vehicle, which has the same beneficial effects as the above-mentioned three-port bidirectional isolation converter.

Description of drawings

In order to describe the embodiments of the present application more clearly, the following will briefly introduce the drawings that are used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, which are not relevant to ordinary skills in the art. As far as personnel are concerned, other drawings can also be obtained from these drawings on the premise of no creative work.

1 is a schematic structural diagram of a three-port bidirectional converter in the prior art;

2 is a schematic structural diagram of another three-port bidirectional converter provided by the application;

Fig. 3a is a kind of pulse signal waveform diagram provided by the application;

Fig. 3b is another pulse signal waveform diagram provided by the application;

4a is a schematic diagram of a voltage mode provided by the application;

FIG. 4b is another schematic diagram of voltage mode provided by the application;

Fig. 4c is another schematic diagram of voltage mode provided by the application;

FIG. 4d is a schematic diagram of another voltage mode provided by the application;

FIG. 4e is a schematic diagram of another voltage mode provided by the application;

FIG. 4f is another schematic diagram of voltage mode provided by the application;

4g is another schematic diagram of voltage mode provided by the application;

FIG. 4h is a schematic diagram of another voltage mode provided by the application;

FIG. 4i is a schematic diagram of another voltage mode provided by the application;

FIG. 4j is another schematic diagram of voltage mode provided by the application;

FIG. 5 is a schematic diagram of another voltage mode boundary condition provided by the present application.

Detailed ways

The core of the present application is to provide a three-port bidirectional isolated converter and a rail transit vehicle, in which only one level of DC/DC conversion is performed between any two ports, and the conversion efficiency is high, while reducing power switching devices, energy storage elements, The number of filter elements and control elements, high power density and low cost.

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

Please refer to FIG. 2. FIG. 2 is a schematic structural diagram of a three-port bidirectional isolated converter provided by the application. The three-port bidirectional isolated converter includes a control module 1 and a conversion circuit 2. The conversion circuit 2 includes an inductance module and a A dual active bridge conversion circuit connected to the first port V1, the second port V2, and the third port V3, the inductance module and the input full-bridge conversion module in the dual active bridge conversion circuit form two interleaved parallel bidirectional buck-boost conversion circuit;

The control module 1 is used to control the first port V1 and the second port V2 to perform the corresponding power bidirectional conversion operation through the bidirectional buck-boost conversion circuit, and control the first port V1 and the third port V3 to perform the corresponding power through the dual active bridge conversion circuit. The power bidirectional conversion operation is controlled, and the second port V2 and the third port V3 are controlled to perform the corresponding power bidirectional conversion operation through the dual active bridge conversion circuit.

In this embodiment, the three-port bidirectional isolation converter is provided with a first port V1, a second port V2 and a third port V3, wherein the first port V1 is used to connect with the power supply bus, and the power supply bus includes the motor vehicle traction intermediate DC bus, Urban rail DC distribution network, etc. The second port V2 is used to connect with the energy storage device, which includes power batteries and super capacitors, etc., and the third port V3 is used to connect to the load, which includes on-board chargers, auxiliary converters, etc. device, etc.

Specifically, the dual active bridge conversion circuit includes an input full-bridge conversion module, an output full-bridge conversion module, and a resonant inductor Lr and a transformer Tr arranged between the input full-bridge conversion module and the output full-bridge conversion module, and the input full-bridge conversion module The modules are respectively connected with the first port V1 and the second port V2, and the output full-bridge conversion module is connected with the third port V3. The input full-bridge circuit includes a first filter capacitor C1, a second filter capacitor C2 and a first full-bridge circuit, and the first full-bridge circuit includes a first primary bridge arm M1 composed of a first switch module S1 and a second switch module S2 , the second primary bridge arm M2 composed of the third switch module S3 and the fourth switch module S4. The first inductor L1 and the second inductor L2 in the inductor module are composed of the first filter capacitor C1, the second filter capacitor C2, the first switch module S1, the second switch module S2, the third switch module S3 and the fourth switch module S4 Two-way staggered parallel bidirectional buck-boost conversion circuit.

The output full-bridge conversion module includes a second full-bridge circuit and a third filter capacitor C3, the second full-bridge circuit is connected to the secondary side of the transformer Tr, and the third filter capacitor C3 is connected in parallel with the second full-bridge circuit. The second full bridge circuit includes a first secondary bridge arm M3 formed by a fifth switch module Q1 and a sixth switch module Q2, and a second secondary bridge arm M4 formed by a seventh switch module Q3 and an eighth switch module Q4.

The control module controls the bidirectional buck-boost conversion circuit, which can realize the buck-boost conversion between the first port V1 and the second port V2, and the control module controls the dual active bridge conversion circuit, which can realize the first port V1 and the second port V2. Power bidirectional conversion operation between the third port V3, the second port V2 and the third port V3. The bidirectional buck-boost conversion circuit or the dual active bridge conversion circuit only performs one-level DC/DC conversion. Therefore, with the structure of this embodiment, only one level of DC/DC conversion is required between any two ports. efficient.

It can be understood that this embodiment multiplexes the input full-bridge conversion module in the dual active bridge conversion circuit, and together with the inductance module constitutes a two-way staggered parallel bidirectional buck-boost conversion circuit, which reduces the number of power switching devices and energy storage elements. , the number of filter components, high power density, low cost.

Further, the bidirectional buck-boost conversion circuit and the dual active bridge conversion circuit both realize energy conversion by turning on/off the switch module of the internal full bridge circuit, and the present application only uses one control module 1 to convert to the dual active bridge. The circuit and the bidirectional buck-boost conversion circuit output the corresponding pulse signal, which can control the on/off of their respective internal switch modules, thereby realizing the energy conversion between any two ports, further improving the power density and reducing the cost.

Specifically, the switch module may include a switch tube, and may also include a diode in anti-parallel with the switch tube. The switch tube may be selected from IGBT (Insulated Gate Bipolar Transistor, insulated gate bipolar transistor), GTO (Gate Turn-off Thyristor, gate electrode) Turn-off thyristor), GTR (Giant Transistor, high power transistor or power transistor), MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor, metal oxide semiconductor field effect transistor), IGCT (Integrated Gate-Commutated Thyristor, integrated gate commutation thyristor), IEGT (Injection Enhanced Gate Transistor, electron injection enhanced gate transistor) or other semiconductor switching devices with similar functions.

On the basis of the above-mentioned embodiment:

As a preferred embodiment, the process of performing a corresponding bidirectional power conversion operation by a bidirectional buck-boost conversion circuit includes:

Output the corresponding pulse signal to the bidirectional buck-boost conversion circuit. When the first duty cycle of the pulse signal is less than 0.5, the bidirectional buck-boost conversion circuit performs a step-down operation. When the first duty cycle of the pulse signal is greater than 0.5, A bidirectional buck-boost converter circuit performs the boost operation.

Specifically, the first port V1 and the second port V2 are connected through two interleaved parallel bidirectional buck-boost conversion circuits, and the control module 1 uses PWM control to control the input full-bridge conversion module in the bidirectional buck-boost conversion circuit, to The switch module of the input full-bridge conversion module inputs the pulse signal used to realize PWM control. The schematic diagram of the pulse signal is shown in Figure 3a and Figure 3b, where Ths is the half switching period, Ts is the switching period, and D1 is the control _of the second switch. The duty ratio of the pulse signal of the module S2 and the fourth switch module S4, 1-D ₁ is to control the duty ratio of the pulse signal of the first switch module S1 and the third switch module S3, control the third switch module S3 and the fourth switch module S3 and the fourth The pulse signal of the switch module S4 lags behind the pulse signal for controlling the first switch module S1 and the second switch module S2 by a phase angle of 180° respectively.

As shown in Figure 3a, when D ₁ <0.5, the PWM control of the bidirectional buck-boost conversion circuit makes the first primary side bridge arm M1 and the second primary side in the first full-bridge circuit in the dual active bridge conversion circuit The output voltage V _AB of the bridge arm M2 is a rectangular wave with a duty ratio of D ₁ ; as shown in Figure 3b, when D ₁ > 0.5, the PWM control of the bidirectional buck-boost conversion circuit makes the first in the dual active bridge conversion circuit. The output voltage V _AB of the first primary bridge arm M1 and the second primary bridge arm M2 in a full-bridge circuit is a rectangular wave with a duty ratio of 1-D ₁ , and its amplitude is V ₁ +V ₂ , V ₁ is the voltage of the first port V1, and V ₂ is the voltage of the second port V2. Then the relationship between the first port V1 and the second port V2 is satisfied:

When D ₁ <0.5, V ₂ <V ₁ , the step-down conversion from the first port V1 to the second port V2 is realized, and when D ₁ >0.5, V ₂ >V ₁ , the first port V1 to the second port V1 is realized. The boost conversion of the port V2, in this way, the bidirectional buck-boost conversion circuit realizes the wide voltage range conversion between the first port V1 and the second port V2, which can satisfy the wide voltage change between the first port V1 and the second port V2 range of application requirements.

As a preferred embodiment, the process of performing the corresponding bidirectional power conversion operation by the dual active bridge conversion circuit includes:

As a preferred embodiment, the process of performing the phase-shift control operation on the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit includes:

Input the corresponding pulse signal to the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit respectively, and the phase shift between the pulse signal corresponding to the input full-bridge conversion module and the pulse signal corresponding to the output full-bridge module The time is the product of the phase shift angle and the half switching period.

As a preferred embodiment, the process of inputting the corresponding pulse signal to the output full-bridge transformation module includes:

The corresponding pulse signals are respectively input to the first secondary side bridge arm M3 and the second secondary side bridge arm M4 in the output full-bridge conversion module, and the pulse signal corresponding to the first secondary side bridge arm M3 is ahead of the second secondary side bridge arm M4. The time of the pulse signal is the product of the second duty cycle and the switching period.

Specifically, the duty cycle of the pulse signals controlling the four switch modules of the second full-bridge circuit in the dual active bridge conversion circuit is 0.5, and the pulse signals controlling the fifth switch module Q1 and the sixth switch module Q2 are 180° complementary, The pulse signals for controlling the seventh switch module Q3 and the eighth switch module Q4 are 180° complementary. The fifth switch module Q1 and the eighth switch module Q4 are in the same phase, and the sixth switch module Q2 and the seventh switch module Q3 are in the same phase, so the output voltage V _CD of the second full-bridge circuit in the dual active bridge conversion circuit is the duty cycle Than 50% of the square wave, its amplitude is V ₃ . Phase-shift control is used for the first full-bridge circuit and the second full-bridge circuit in the dual active bridge conversion circuit. The phase shift time is Dψ×Ths, and the size and positive and negative of Dψ are used to control the power of the dual active bridge conversion circuit. The size and direction of the transmission, thus realizing the PWM and single phase shift control of the dual active bridge conversion circuit.

Further, phase shift control can also be used between the two secondary side bridge arms in the second full bridge circuit of the dual active bridge conversion circuit, that is, the fifth switch module Q1 and the sixth switch module in the first secondary side bridge arm M3. The time when the control pulse of the switch module Q2 leads the seventh switch module Q3 and the eighth switch module Q4 in the second secondary side bridge arm M4 respectively is D ₂ ×Ts, then the output voltage V _CD of the secondary side of the dual active bridge conversion circuit is Rectangular wave with duty cycle D ₂ . In this way, PWM and dual phase shift control of the dual active bridge conversion circuit can be realized, and the circulating current loss can be reduced when the primary and secondary side voltages of the dual active bridge conversion circuit are not matched, thereby improving the conversion efficiency.

The voltage on the primary side of the dual active bridge conversion circuit is denoted as V _bus , there are:

It can be seen from the above formula that V _bus is higher than the voltage of V ₂ , which can reduce the bus current, thereby reducing the conduction loss and improving the efficiency of the dual active bridge conversion circuit.

As a preferred embodiment, the control module 1 is also used for:

Determine the voltage mode of the three-port bidirectional isolated converter;

The optimal operating point corresponding to each voltage mode is obtained, and the optimal operating point is the operating point that minimizes the return power of the three-port bidirectional isolated converter under the target output power.

As a preferred embodiment, the process of obtaining the optimal operating point corresponding to each voltage mode includes:

The optimal operating point corresponding to each voltage mode is obtained by the Lagrangian multiplier method.

As a preferred embodiment, the process of obtaining the optimal operating point corresponding to each voltage mode by the Lagrangian multiplier method includes:

Obtain multiple operating points corresponding to each voltage mode by the Lagrangian multiplier method;

Considering that there are three control degrees of freedom in PWM and dual-phase-shift control, different combinations of D ₁ , D ₂ and Dψ will appear during control, resulting in different combinations of duty cycle and phase relationship for V _AB and V _CD . The duty cycle and phase relationship between V _AB and V _CD is called the voltage mode. The difference between the converted values of V _AB and V _CD is applied to the resonant inductor Lr, so that the current iLr on the resonant inductor Lr has different slopes. When Dψ> ₀ , different combinations of D1, D2, and _Dψ can cause the converter to exhibit 10 different voltage modes, as shown in Figures 4a to 4j.

Specifically, the copper loss of the high frequency transformer Tr is proportional to the square of the effective value of the current iLr of the resonant inductor Lr. In order to reduce the copper loss of the transformer Tr, the smaller the effective value of the current iLr of the resonant inductor Lr, the better. From this point of view, the modes shown in FIGS. 4d and 4i contradict the goal of reducing the effective value of the current iLr of the resonant inductor Lr. Taking Fig. 4d as an example, when changing the time period of θ ₂ -θ ₁ , the output power of the converter remains unchanged, but reducing the time period of θ ₂ -θ ₁ can significantly reduce the effective current iLr of the resonant inductor Lr. Therefore, in the stage of θ ₁ ≤ ωt ≤ θ ₂ , the current iLr of the resonant inductor Lr only circulates on the primary side, which is not beneficial to increase the power transmission, but only increases the effective value of the inductor current, resulting in increased loss. Likewise, Figure 4i is the same. By limiting the range of the duty ratios D ₁ and D ₂ , it can be ensured that the converter does not work in the two voltage modes shown in FIG. 4d and FIG. 4i. Further, the boundary conditions of each voltage mode are shown in Figure 5.

When the duty cycle D ₁ is constant, there are various combinations of (D ₂ , Dψ) that can make the output power of the converter the same. The working point is the optimal working point.

It can be understood that whether D ₁ ≤ 0.5 or D ₁ ≥ 0.5, the return power has the following trend: when the output power of the converter is small, that is, when the phase shift angle Dψ is small, as the duty cycle D ₂ increases, The return power of the large converter gradually decreases; when the output power increases and the phase shift angle Dψ is close to 0.5, the return power of the converter basically does not change with the change of D ₂ , but increases with the increase of the phase shift angle. big. According to the variation law of the return power with the control variables D ₂ and Dψ under different conditions, the working point with the minimum return power can be found to realize the optimization of the return power, so as to reduce the return power loss of the converter and improve the power conversion efficiency.

Under the condition of the same output power Po, the optimal operating point (D ₂ , Dψ) can be selected by the Lagrange multiplier method so that the return power is the minimum value. First, the Lagrangian function is constructed as f(D ₂ ,Dψ)=Pb(D ₂ ,Dψ)+λPo(D ₂ ,Dψ) according to the constraints and the objective function; then each voltage mode is corresponding to different conditions _The expressions of the return _power and output power of the

The relational expressions of D ₁ , D ₂ and Dψ can be obtained by solving. If the relationship satisfies the boundary conditions of the corresponding mode, the combination of D ₁ , D ₂ and Dψ satisfying the relationship can be used as the optimal operating point.

In summary, the present application can realize the bidirectional flow of energy between any two ports of the three ports, and realize the operation of a wide voltage variation range; the power device and the control module are multiplexed, the structure is simple, and the power density is high; any two ports are connected. It only undergoes one-stage DC-DC conversion, and the conversion efficiency is high; the current reduction reduces the conduction loss and further improves the efficiency of the converter; realizes the multiplexing of the power switching device and the control unit, with a simple structure, high power density, and components. Low cost and low cost; adopting PWM and dual phase-shift control strategy can reduce circulating current loss and improve conversion efficiency; control according to the minimum return power of the converter, that is, the optimal operating point, to further improve the converter efficiency.

On the other hand, the present application also provides a rail transit vehicle, comprising:

vehicle body;

A three-port bidirectional isolated converter as in any of the above.

For the introduction of a rail transit vehicle provided in the present application, please refer to the above-mentioned embodiments, which will not be repeated in the present application.

The rail transit vehicle provided by the present application has the same beneficial effects as the above-mentioned three-port bidirectional isolation converter.

It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply these entities or operations. There is no such actual relationship or sequence between operations. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article, or device that includes the element.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, this application is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

A three-port bidirectional isolation converter is characterized by comprising a control module and a conversion circuit, the conversion circuit comprising an inductance module and a dual active bridge conversion circuit respectively connected to a first port, a second port and a third port, The inductance module and the input full-bridge conversion module in the dual active bridge conversion circuit form two interleaved parallel bidirectional buck-boost conversion circuits;

The control module is configured to control the first port and the second port to perform a corresponding bidirectional power conversion operation through the bidirectional buck-boost conversion circuit, and control the first port and the third port to pass through the bidirectional buck-boost conversion circuit. The dual active bridge conversion circuit performs a corresponding power bidirectional conversion operation, and the second port and the third port are controlled to perform a corresponding power bidirectional conversion operation through the dual active bridge conversion circuit.
The three-port bidirectional isolated converter according to claim 1, wherein the input full-bridge conversion module comprises a first filter capacitor, a second filter capacitor and a first full-bridge circuit, and the inductance module comprises a first inductor and the second inductor, where:

The first end of the first filter capacitor is respectively connected to the negative electrode of the first port and the first end of the first full-bridge circuit, and the first end of the second filter capacitor is connected to the positive electrode of the second port and the first end of the first full bridge circuit. The second end of the first full-bridge circuit is connected, and the common end after the first filter capacitor and the second filter capacitor are connected are respectively connected to the negative electrode of the second port, the positive electrode of the first port, and the The first end of the first inductor is connected to the first end of the second inductor, the second end of the second inductor is connected to the third end of the first full-bridge circuit, and the first end of the first inductor is connected to the third end of the first full-bridge circuit. The two terminals are connected to the fourth terminal of the first full-bridge circuit.
The three-port bidirectional isolated converter according to claim 2, wherein the first full-bridge circuit comprises:

a first primary bridge arm composed of a first switch module and a second switch module;

a second primary bridge arm composed of a third switch module and a fourth switch module;

The common terminal of the first switch module and the second switch module is used as the third terminal of the first full-bridge circuit, and the common terminal of the third switch module and the fourth switch module is used as the first switch module. The fourth terminal of the full bridge circuit.
The three-port bidirectional isolated converter according to claim 3, wherein the process of performing the corresponding bidirectional power conversion operation by the bidirectional buck-boost conversion circuit comprises:

Output a corresponding pulse signal to the bidirectional buck-boost conversion circuit, when the first duty cycle of the pulse signal is less than 0.5, the bidirectional buck-boost conversion circuit performs a step-down operation, and when the first duty cycle of the pulse signal is less than 0.5, the bidirectional buck-boost conversion circuit performs step-down operation. When a duty cycle is greater than 0.5, the bidirectional buck-boost conversion circuit performs a boosting operation.
The three-port bidirectional isolated converter according to claim 1, wherein the conversion circuit further comprises an output full-bridge conversion module, a transformer and a resonant inductor, wherein:

The input full-bridge conversion module is respectively connected to the first port and the second port, the output full-bridge conversion module is connected to the third port, and the input full-bridge conversion module passes through the resonant inductance and The transformer is connected to the output full-bridge conversion module.
The three-port bidirectional isolated converter according to claim 5, wherein the output full-bridge conversion module comprises a second full-bridge circuit and a third filter capacitor, wherein:

The second full-bridge circuit is connected to the secondary side of the transformer, and the third filter capacitor is connected in parallel with the second full-bridge circuit.
The three-port bidirectional isolated converter according to claim 6, wherein the second full-bridge circuit comprises:

a first secondary side bridge arm composed of a fifth switch module and a sixth switch module;

The second secondary side bridge arm formed by the seventh switch module and the eighth switch module.
The three-port bidirectional isolated converter according to claim 7, wherein the process of performing the corresponding bidirectional power conversion operation by the dual active bridge conversion circuit comprises:

A phase shift control operation is performed on the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit.
The three-port bidirectional isolated converter according to claim 8, wherein the phase-shift control is performed on the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit The operation process includes:

Inputting corresponding pulse signals to the input full-bridge conversion module and the output full-bridge conversion module in the dual active bridge conversion circuit respectively, the pulse signal corresponding to the input full-bridge conversion module and the output full-bridge conversion module The phase shift time between the corresponding pulse signals of the module is the product of the phase shift angle and the half switching period.
three-port bidirectional isolation converter according to claim 9, is characterized in that, the process of inputting corresponding pulse signal to described output full-bridge conversion module comprises:

The corresponding pulse signals are respectively input to the first secondary side bridge arm and the second secondary side bridge arm in the output full-bridge conversion module, and the pulse signal corresponding to the first secondary side bridge arm is ahead of the first secondary side bridge arm. The time of the pulse signal corresponding to the two secondary side bridge arms is the product of the second duty cycle and the switching period.
The three-port bidirectional isolation converter according to any one of claims 1-10, wherein the control module is further used for:

determining a voltage mode of the three-port bidirectional isolated converter;

The optimal operating point corresponding to each of the voltage modes is obtained, and the optimal operating point is the operating point that minimizes the return power of the three-port bidirectional isolated converter under the target output power.
The three-port bidirectional isolated converter according to claim 11, wherein the process of obtaining the optimal operating point corresponding to each of the voltage modes comprises:

The optimal operating point corresponding to each of the voltage modes is obtained by the Lagrange multiplier method.
The three-port bidirectional isolated converter according to claim 12, wherein the process of obtaining the optimal operating point corresponding to each of the voltage modes by the Lagrangian multiplier method comprises:

Obtain a plurality of operating points corresponding to each of the voltage modes by the Lagrangian multiplier method;

The operating point satisfying the boundary conditions of the voltage mode is determined as the optimal operating point.
A rail transit vehicle, comprising:

vehicle body;

The three-port bidirectional isolation converter according to any one of claims 1-13.