阅读说明：本技术 一种车用柔性电-电混合电源系统 (Flexible electricity-electricity hybrid power supply system for vehicle ) 是由 王亚雄 张晨阳 丁阿鑫 于 2019-11-28 设计创作，主要内容包括：本发明提出一种车用柔性电-电混合电源系统,以柔性辅助电源与主电源组合形成车用混合动力电源；所述柔性辅助电源内置有由多个辅助电源单体相互连接组成的最小可操纵单元；最小可操纵单元之间的连接关系可在串联与并联之间切换；最小可操纵单元间形成<I>n</I>个串联连接和<I>m</I>个并联连接的结构；所述<I>n、m</I>为正整数；柔性辅助电源通过更改<I>n、m</I>的值,使柔性辅助电源可在高功率放电和快速充电模式之间切换,并维持主电源的工作电压稳定；本发明需求功率所处的功率区间确定主电源的工作点,柔性改变邻近辅助电源内部模组的连接方式并与主电源直接并联,维持主电源在稳定电压下工作,避免采取经传统的直流/直流变换器连接的能量损耗,提高了经济性。(The invention provides a flexible electric-electric hybrid power supply system for a vehicle, which combines a flexible auxiliary power supply and a main power supply to form a hybrid power supply for the vehicle; the flexible auxiliary power supply is internally provided with a minimum operable unit formed by connecting a plurality of auxiliary power supply units; the connection relation between the minimum steerable units can be switched between series connection and parallel connection; formation between minimum steerable units n A series connection of m A plurality of parallel connected structures; the above-mentioned n、m Is a positive integer; flexible auxiliary power supply through change n、m The value of (3) to enable the flexible auxiliary power supply to be switchable between a high-power discharge mode and a fast charge mode and to maintain the working voltage of the main power supply to be stable; the power interval where the required power is positioned determines the working point of the main power supply, flexibly changes the connection mode of the internal module of the adjacent auxiliary power supply and is directly connected with the main power supplyAnd the main power supply is maintained to work under a stable voltage, the energy loss caused by connection of a traditional direct current/direct current converter is avoided, and the economy is improved.)

1. A vehicle flexible electricity-electricity hybrid power supply system characterized in that: the system combines a flexible auxiliary power supply and a main power supply to form a hybrid power supply for the vehicle; the flexible auxiliary power supply is internally provided with a plurality of minimum operable units formed by connecting flexible auxiliary power supply units; the connection relationship between the minimum operable units is switchable between a series connection and a parallel connection; n series connections and m parallel connections are formed between the minimum operable units; n and m are positive integers; the flexible auxiliary power supply can realize switching between a high-power discharge mode and a quick charge mode by changing the values of n and m, and the working voltage of the main power supply is kept stable.

2. A flexible electric-electric hybrid power supply system for vehicle according to claim 1, characterized in that: the vehicle hybrid power supply is directly connected to a direct current bus and is connected with an alternating current load motor through a direct current alternating current inverter; the flexible auxiliary power supply is directly connected with the main power supply in parallel.

3. A flexible electric-electric hybrid power supply system for vehicle according to claim 1, characterized in that: the main power supply is a fuel cell power supply; the fuel cell power supply comprises components including but not limited to a fuel cell stack, a fuel cell air compressor and a fuel cell hydrogen circulating pump; the minimum operable unit built in the flexible auxiliary power supply is a minimum operable unit with a connection relation capable of being changed in real time; the type of the flexible auxiliary power supply unit can be a super capacitor or a storage battery.

4. A flexible electric-electric hybrid power supply system for vehicle according to claim 1, characterized in that: and if the flexible auxiliary power supply is in a high-charging-voltage quick charging mode, increasing the number n of the minimum operable units of the flexible auxiliary power supply in series connection and reducing the number m of the minimum operable units in parallel connection so as to improve the terminal voltage of the flexible auxiliary power supply and enable the flexible auxiliary power supply to meet the high-charging-voltage requirement.

5. A flexible electric-electric hybrid power supply system for vehicle according to claim 1, characterized in that: when the flexible auxiliary power supply is in a low-charging-voltage quick charging mode or a state of a quick charging mode by vehicle braking energy recovery, the number m of the parallel connection of the flexible auxiliary power supply is increased, and the number n of the series connection of the flexible auxiliary power supply is reduced, so that the current of the flexible auxiliary power supply is increased, and the charging rate of the flexible auxiliary power supply under low voltage is improved.

6. A flexible electric-electric hybrid power supply system for vehicle according to claim 1, characterized in that: the main power supply is a fuel cell power supply, and when the flexible auxiliary power supply maintains the stable working voltage of the main power supply by changing the values of n and m, the working method comprises the following steps;

step A1, determining an output power interval where the power value is located by calculation according to the magnitude of the required power, and calculating the output voltage of the fuel cell power supply as the bus reference voltage according to the median power value of the interval;

and step A2, changing the serial connection and parallel connection quantity of the minimum operable units in the adjacent flexible auxiliary power supply modules, so that the terminal voltage value of the flexible auxiliary power supply modules can be flexibly switched to be close to and stable with the bus reference voltage value, thereby ensuring the stable and efficient operation of the fuel cell.

7. The flexible electric-electric hybrid power supply system for vehicle according to claim 6, characterized in that: the calculation of the serial number n and the parallel number m of the minimum steerable unit of the flexible auxiliary power supply comprises the following steps:

step B1, calculating the required power of the automobile according to the running speed working condition of the automobile: there is (equation 1) as:

wherein: m is the mass of the vehicle, f is the coefficient of friction, v is the speed of travel of the vehicle, C_DThe coefficient of air resistance of the automobile, A is the windward area, η is the transmission efficiency of the automobile, α is the inclination angle of the ramp;

step B2, dividing the power of fuel cell power source into R zonesEach interval having a length P_max/R；P_maxThe maximum output power of the fuel cell is the power interval of the fuel cell power supply, which can be divided into 0, P_max/R]，[P_max/R,2P_max/R]，[2P_max/R,3P_max/R]，[3P_max/R,4P_max/R]，……，[P_max-P_max/R,P_max](ii) a Median power P of the interval_iAre respectively P₁,P₂,P₃……P_RAs shown in (equation 2);

step B3, judging a power interval where the required power of the automobile is located according to the power interval of the fuel cell power supply in the step B2 by using the required power which is required to be borne by the hybrid power supply and calculated in the step B1, and defining the interval as a working interval of the fuel cell power supply;

step B4, according to the working interval of the fuel cell determined in step B3, the median power P of the working interval of the fuel cell power supply is obtained according to the formula 2_iAnd obtaining the power P of the fuel cell by using the power-voltage curve of the fuel cell_iCorresponding voltage V of_fc；

Step B5 according to the voltage V in step B4_fcAnd calculating the number of parallel branches of the flexible auxiliary power supply and the minimum number of steerable units required to be connected in series for each parallel branch by an integer function, wherein the calculation is shown in a formula 3 and a formula 4:

wherein: n is the minimum total number of the controllable units of the super capacitor module; n is the minimum operable unit number of each parallel branch of the flexible auxiliary power supply in series connection, and m is the minimum operable unit number of the super capacitor moduleNumber of parallel branches of longitudinal units, V_auxMinimum operable cell voltage for flexible auxiliary power supply]Is a rounding function.

8. A flexible electric-electric hybrid power supply system for vehicle according to claim 7, characterized in that: the flexible auxiliary power supply designs the serial-parallel number m and n of the flexible auxiliary power supply according to the actual power requirement through the steps B1 to B5, and switches the connection mode of the internal minimum controllable unit of the auxiliary power supply in real time, so that the terminal voltage of the flexible auxiliary power supply module is adjusted, the direct-current bus voltage is stabilized, the fluctuation power is absorbed, and the voltage of the fuel cell is kept stable in a working interval.

9. A flexible electric-electric hybrid power supply system for vehicle according to claim 8, characterized in that: in the flexible auxiliary power supply and in a connecting circuit among the flexible auxiliary power supplies, a switch responsible for switching the serial and parallel states is formed by connecting two reverse IGBTs in series, so that the high control potential is switched on, and the low control potential is switched off.

Technical Field

The invention relates to the technical field of power supplies, in particular to a flexible electric-electric hybrid power supply system for a vehicle.

Background

With the rapid development of global economy, global problems such as energy shortage, environmental pollution, climate warming and the like become increasingly prominent. Among them, in the automobile industry, the development of automobiles with low fuel consumption and less exhaust emission has become an important development target in the automobile industry all over the world.

In order to actively respond to the national energy-saving and emission-reducing policy, the development of new energy automobiles becomes a consensus so as to reduce the problems of environmental pollution, resource shortage and the like faced by internal combustion engine automobiles. In the development process of new energy automobiles, the development of hybrid electric automobiles is one of the mainstream trends of the current development. The reason is that on one hand, the hybrid electric vehicle can reduce the emission of waste, reduce the pollution of the traditional internal combustion engine to the environment and reduce the dependence on fossil energy; on the other hand, the hybrid electric vehicle effectively avoids the defect of insufficient cruising distance of the pure electric vehicle. Therefore, the hybrid electric vehicle plays a role of starting before and after in the development process of the vehicle, and is one of the key directions of the development of new energy vehicles.

Recently, electric-electric hybrid power systems have also gained more and more attention due to their energy saving, high efficiency and simple structure. In order to enable an electric-electric hybrid electric vehicle to better meet working condition requirements, economy and dynamic performance, different electric-electric hybrid power configurations and control methods have become important research points. The topological structure of the current automobile hybrid power system is generally that a main energy supply power source is connected with a direct current/direct current converter, and an auxiliary power source is connected with a bus through a bidirectional direct current/direct current converter to carry out combined power supply. The structure isolates the main power supply and the auxiliary power supply through the direct current/direct current converter, so that the problem of inconsistent output voltage of the main power supply and the auxiliary power supply can be effectively solved, the main power supply and the auxiliary power supply can be controlled to supply power independently, and the control of the power supply is more accurate. However, the electric-electric hybrid power system also has some problems at present, on one hand, the electric-electric hybrid power system needs to design a complex controller because the electric-electric hybrid power system needs to accurately control the direct current/direct current converter, so that the calculated amount of the system is greatly increased; on the other hand, the energy utilization of the system is reduced due to the power loss of the dc converter itself. If the structure of the hybrid power system can be changed, the use of a direct current/direct current converter is reduced, the system structure is simplified, the system efficiency is improved, and the improvement of the overall vehicle performance is of great significance.

Disclosure of Invention

In view of the above, the present invention provides a flexible electric-electric hybrid power supply system for a vehicle, which can determine a required power of the vehicle according to a driving condition of a hybrid vehicle, determine a working point of a fuel cell according to a power interval where the required power is located, further change an auxiliary power supply module in a serial-parallel connection manner adjacent to a minimum operable unit to obtain a flexible working manner, and directly connect a main power supply and a flexible auxiliary power supply module with a bus, thereby avoiding the adoption of a conventional dc/dc converter, reducing energy loss, and improving economy.

The invention adopts the following technical scheme.

A flexible electric-electric hybrid power supply system for a vehicle, the system combining a flexible auxiliary power supply and a main power supply to form a hybrid power supply for the vehicle; the flexible auxiliary power supply is internally provided with a plurality of minimum operable units formed by connecting flexible auxiliary power supply units; the connection relationship between the minimum operable units is switchable between a series connection and a parallel connection; n series connections and m parallel connections are formed between the minimum operable units; n and m are positive integers; the flexible auxiliary power supply can realize switching between a high-power discharge mode and a quick charge mode by changing the values of n and m, and the working voltage of the main power supply is kept stable.

The vehicle hybrid power supply is directly connected to a direct current bus and is connected with an alternating current load motor through a direct current alternating current inverter; the flexible auxiliary power supply is directly connected with the main power supply in parallel.

The main power supply is a fuel cell power supply; the fuel cell power supply comprises components including but not limited to a fuel cell stack, a fuel cell air compressor and a fuel cell hydrogen circulating pump; the minimum operable unit built in the flexible auxiliary power supply is a minimum operable unit with a connection relation capable of being changed in real time; the type of the flexible auxiliary power supply unit can be a super capacitor or a storage battery.

And if the flexible auxiliary power supply is in a high-charging-voltage quick charging mode, increasing the number n of the minimum operable units of the flexible auxiliary power supply in series connection and reducing the number m of the minimum operable units in parallel connection so as to improve the terminal voltage of the flexible auxiliary power supply and enable the flexible auxiliary power supply to meet the high-charging-voltage requirement.

When the flexible auxiliary power supply is in a low-charging-voltage quick charging mode or a state of a quick charging mode by vehicle braking energy recovery, the number m of the parallel connection of the flexible auxiliary power supply is increased, and the number n of the series connection of the flexible auxiliary power supply is reduced, so that the current of the flexible auxiliary power supply is increased, and the charging rate of the flexible auxiliary power supply under low voltage is improved.

The main power supply is a fuel cell power supply, and when the flexible auxiliary power supply maintains the stable working voltage of the main power supply by changing the values of n and m, the working method comprises the following steps;

step A1, determining an output power interval where the power value is located by calculation according to the magnitude of the required power, and calculating the output voltage of the fuel cell power supply as the bus reference voltage according to the median power value of the interval;

and step A2, changing the serial connection and parallel connection quantity of the minimum operable units in the adjacent flexible auxiliary power supply modules, so that the terminal voltage value of the flexible auxiliary power supply modules can be flexibly switched to be close to and stable with the bus reference voltage value, thereby ensuring the stable and efficient operation of the fuel cell.

According to the steps A1 and A2, the calculation of the serial number n and the parallel number m of the minimum steerable unit of the flexible auxiliary power supply comprises the following steps:

step B1, calculating the required power of the automobile according to the running speed working condition of the automobile:

wherein: m is the mass of the vehicle, f is the coefficient of friction, v is the speed of travel of the vehicle, C_DThe coefficient of air resistance of the automobile, A is the windward area, η is the transmission efficiency of the automobile, α is the inclination angle of the ramp;

step B2, dividing the power of the fuel cell power supply into R sections, each section having a length of P_max/R；P_maxThe maximum output power of the fuel cell is the power interval of the fuel cell power supply, which can be divided into 0, P_max/R]，[P_max/R,2P_max/R]，[2P_max/R,3P_max/R]，[3P_max/R,4P_max/R]，……，[P_max-P_max/R,P_max](ii) a Median power P of the interval_iAre respectively P₁,P₂,P₃……P_RAs shown in (equation 2);

step B3, judging a power interval where the required power of the automobile is located according to the power interval of the fuel cell power supply in the step B2 by using the required power which is required to be borne by the hybrid power supply and calculated in the step B1, and defining the interval as a working interval of the fuel cell power supply;

step B4, according to the working interval of the fuel cell determined in step B3, the median power P of the working interval of the fuel cell power supply is obtained according to the formula 2_iAnd obtaining the power P of the fuel cell by using the power-voltage curve of the fuel cell_iCorresponding voltage V of_fc；

Step B5 according to the voltage V in step B4_fcAnd calculating the number of parallel branches of the flexible auxiliary power supply and the minimum number of steerable units required to be connected in series for each parallel branch by an integer function, wherein the calculation is shown in a formula 3 and a formula 4:

wherein: n is the minimum total number of the controllable units of the super capacitor module; n is the minimum number of the controllable units of each parallel branch of the flexible auxiliary power supply in series connection, m is the number of the parallel branches of the minimum controllable units of the super capacitor module, and V_auxMinimum operable cell voltage for flexible auxiliary power supply]Is a rounding function.

The flexible auxiliary power supply designs the serial-parallel number m and n of the flexible auxiliary power supply according to the actual power requirement through the steps B1 to B5, and switches the connection mode of the internal minimum controllable unit of the auxiliary power supply in real time, so that the terminal voltage of the flexible auxiliary power supply module is adjusted, the direct-current bus voltage is stabilized, the fluctuation power is absorbed, and the voltage of the fuel cell is kept stable in a working interval.

In the flexible auxiliary power supply and in a connecting circuit among the flexible auxiliary power supplies, a switch responsible for switching the serial and parallel states is formed by connecting two reverse IGBTs in series, so that the high control potential is switched on, and the low control potential is switched off.

The invention has the advantages that:

1. the traditional mode that an auxiliary power supply and a main power supply are connected with a bus through a direct-current converter is abandoned, the power supply structure is simplified, and the power loss of the direct-current converter is reduced.

2. The novel structure that any adjacent auxiliary power supply structure is changeable is adopted, the fluctuation of load power is alleviated, and the stable work of the main power supply under ideal working voltage is ensured.

3. Adopt the changeable novel structure of arbitrary adjacent auxiliary power supply structure, effectual improvement auxiliary power supply's charge rate avoids auxiliary power supply to be punctured by high charging voltage simultaneously.

Drawings

The invention is described in further detail below with reference to the following figures and detailed description:

FIG. 1 is a schematic diagram of the system architecture of the present invention;

FIG. 2 is a schematic diagram of a connection structure of a flexible auxiliary power supply;

FIG. 3 is a schematic diagram of a partial parallel structure of a flexible auxiliary power supply

FIG. 4 is a schematic diagram of the smallest operable units in the flexible auxiliary power supply when all connected in series;

FIG. 5 is a schematic diagram of the smallest operable units in the flexible auxiliary power supply when all are connected in parallel;

FIG. 6 is a schematic diagram of the overall structure of a simulation model of the flexible auxiliary power supply;

FIG. 7 is a schematic diagram of the output power of a fuel cell power supply of a flexible electric-electric hybrid power supply system;

FIG. 8 is a schematic diagram of the output power of the fuel cell power supply independent power supply system;

FIG. 9 is a schematic diagram of the independent output voltage of the independent power supply system of the fuel cell power supply;

FIG. 10 is a schematic diagram of the output voltage of a fuel cell power supply of a flexible electric-electric hybrid power supply system;

FIG. 11 is a schematic diagram of output power of a variable structure super capacitor module of the flexible electric-electric hybrid power system.

Detailed Description

1-11, a flexible electric-electric hybrid power supply system for a vehicle, the system combining a flexible auxiliary power supply and a main power supply to form a hybrid power supply for the vehicle; the flexible auxiliary power supply is internally provided with a plurality of minimum operable units formed by connecting flexible auxiliary power supply units; the connection relationship between the minimum operable units is switchable between a series connection and a parallel connection; n series connections and m parallel connections are formed between the minimum operable units; n and m are positive integers; the flexible auxiliary power supply can realize switching between a high-power discharge mode and a quick charge mode by changing the values of n and m, and the working voltage of the main power supply is kept stable.

The vehicle hybrid power supply is directly connected to a direct current bus and is connected with an alternating current load motor through a direct current alternating current inverter; the flexible auxiliary power supply is directly connected with the main power supply in parallel.

The main power supply is a fuel cell power supply; the fuel cell power supply comprises components including but not limited to a fuel cell stack, a fuel cell air compressor and a fuel cell hydrogen circulating pump; the minimum operable unit built in the flexible auxiliary power supply is a minimum operable unit with a connection relation capable of being changed in real time; the type of the flexible auxiliary power supply unit can be a super capacitor or a storage battery.

And if the flexible auxiliary power supply is in a high-charging-voltage quick charging mode, increasing the number n of the minimum operable units of the flexible auxiliary power supply in series connection and reducing the number m of the minimum operable units in parallel connection so as to improve the terminal voltage of the flexible auxiliary power supply and enable the flexible auxiliary power supply to meet the high-charging-voltage requirement.

When the flexible auxiliary power supply is in a low-charging-voltage quick charging mode or a state of a quick charging mode by vehicle braking energy recovery, the number m of the parallel connection of the flexible auxiliary power supply is increased, and the number n of the series connection of the flexible auxiliary power supply is reduced, so that the current of the flexible auxiliary power supply is increased, and the charging rate of the flexible auxiliary power supply under low voltage is improved.

The main power supply is a fuel cell power supply, and when the flexible auxiliary power supply maintains the stable working voltage of the main power supply by changing the values of n and m, the working method comprises the following steps;

step A1, determining an output power interval where the power value is located by calculation according to the magnitude of the required power, and calculating the output voltage of the fuel cell power supply as the bus reference voltage according to the median power value of the interval;

and step A2, changing the serial connection and parallel connection quantity of the minimum operable units in the adjacent flexible auxiliary power supply modules, so that the terminal voltage value of the flexible auxiliary power supply modules can be flexibly switched to be close to and stable with the bus reference voltage value, thereby ensuring the stable and efficient operation of the fuel cell.

According to the steps A1 and A2, the calculation of the serial number n and the parallel number m of the minimum steerable unit of the flexible auxiliary power supply comprises the following steps:

step B1, calculating the required power of the automobile according to the running speed working condition of the automobile:

wherein: m is the mass of the vehicle, f is the coefficient of friction, v is the speed of travel of the vehicle, C_DThe coefficient of air resistance of the automobile, A is the windward area, η is the transmission efficiency of the automobile, α is the inclination angle of the ramp;

step B2, dividing the power of the fuel cell power supply into R sections, each section having a length of P_max/R；P_maxThe maximum output power of the fuel cell is the power interval of the fuel cell power supply, which can be divided into 0, P_max/R]，[P_max/R,2P_max/R]，[2P_max/R,3P_max/R]，[3P_max/R,4P_max/R]，……，[P_max-P_max/R,P_max](ii) a Median power P of the interval_iAre respectively P₁,P₂,P₃……P_RAs shown in (equation 2);

step B3, judging a power interval where the required power of the automobile is located according to the power interval of the fuel cell power supply in the step B2 by using the required power which is required to be borne by the hybrid power supply and calculated in the step B1, and defining the interval as a working interval of the fuel cell power supply;

step B4, according to the working interval of the fuel cell determined in step B3, the median power P of the working interval of the fuel cell power supply is obtained according to the formula 2_iAnd obtaining the power P of the fuel cell by using the power-voltage curve of the fuel cell_iCorresponding voltage V of_fc；

Step B5 according to the voltage V in step B4_fcAnd calculating the number of parallel branches of the flexible auxiliary power supply and the minimum number of steerable units required to be connected in series for each parallel branch by an integer function, wherein the calculation is shown in a formula 3 and a formula 4:

wherein: n is the minimum total number of the controllable units of the super capacitor module; n is the minimum number of the controllable units of each parallel branch of the flexible auxiliary power supply in series connection, m is the number of the parallel branches of the minimum controllable units of the super capacitor module, and V_auxMinimum operable cell voltage for flexible auxiliary power supply]Is a rounding function.

In this embodiment, a variable structure super capacitor is selected as a flexible auxiliary power supply for example. The flexible auxiliary power supply consists of a variable structure super capacitor module; the series structure and the parallel structure between any adjacent minimum operable units in the variable structure super capacitor module can be flexibly switched; through the steps B1 to B5, the flexible auxiliary power supply, namely the variable structure super capacitor module, is designed according to the actual power requirement, the serial-parallel number m and n of the flexible auxiliary power supply are designed, the connection mode of the internal minimum controllable unit of the auxiliary power supply is switched in real time, the terminal voltage of the flexible auxiliary power supply module is adjusted, the direct-current bus voltage is stabilized, the fluctuation power is absorbed, and the voltage of the fuel cell is kept stable in the working interval.

In the flexible auxiliary power supply and in a connecting circuit among the flexible auxiliary power supplies, a switch responsible for switching the serial and parallel states is formed by connecting two reverse IGBTs in series, so that the high control potential is switched on, and the low control potential is switched off.