An electric drive main power circuit applied to a new energy vehicle and the new energy vehicle

Abstract

The embodiment of the application discloses an electric drive main power circuit applied to a new energy automobile and the new energy automobile, the electric drive main power circuit comprises a DC-DC module and a new energy automobile electric drive inverter, an output end of a new energy automobile power battery is connected to an input side of the DC-DC module, and an input end of the new energy automobile electric drive inverter is connected to an output side of the DC-DC module, so that the output voltage of the new energy automobile power battery is transmitted to the input side of the new energy automobile electric drive inverter through voltage reduction. The mode of adding the DC-DC module for voltage reduction before the new energy automobile electric drive inverter can realize adjustment of the input voltage of the electric drive inverter according to the actual working condition of the new energy automobile, so that the loss of the electric drive inverter and the efficiency of the automobile power control system as a whole are adjusted.

Description

Technical Field

[0001] This invention relates to the field of power electronics system technology, and in particular to an electric drive main power circuit for new energy vehicles and the new energy vehicle itself. Background Technology

[0002] In recent years, the new energy vehicle market has developed rapidly, but insufficient range remains a major challenge for new energy vehicles in competing with traditional fuel vehicles. In the three-electric system of new energy vehicles, the electric drive inverter is a crucial component of the powertrain system, and its losses and efficiency have a significant impact on the overall vehicle efficiency and range. Therefore, control strategies for high-efficiency electric drive inverters have always been an important research direction for new energy vehicles.

[0003] The 800V voltage platform has always been the development direction of modern new energy vehicles. Compared with 400V new energy vehicles, 800V new energy vehicles can provide higher charging efficiency and longer range. However, the higher inverter output voltage will bring higher power transistor switching losses, which will seriously affect the inverter's operating efficiency under low-speed conditions. Currently, the methods to optimize the efficiency of electric drive inverters at the hardware level generally consider optimizing power devices or adding a front-end Boost DC-DC converter module. However, using all SiC devices will significantly increase the hardware cost of the electric drive inverter, while using a Boost DC-DC converter module will reduce the voltage level of the power battery, thereby reducing the battery charging power. In some cases, it is necessary to ensure a high charging power for the new energy vehicle's power battery while ensuring low switching losses in the electric drive inverter. To achieve this, existing technologies generally use multiple power battery banks connected in series and parallel. When a higher battery voltage is required, multiple power battery banks are connected in series; when a lower battery voltage is required, multiple power battery banks are connected in parallel. However, this method may cause voltage imbalance during battery charging, thereby damaging the battery. At the same time, the voltage adjustment range is also limited during battery discharge. Summary of the Invention

[0004] This application provides an electric drive main power circuit and a new energy vehicle for use in new energy vehicles, which helps to ensure high charging power of the new energy vehicle's power battery while ensuring low switching losses of the electric drive inverter.

[0005] The first aspect of this application provides an electric drive main power circuit for new energy vehicles. The electric drive main power circuit includes a DC-DC converter module and a new energy vehicle electric drive inverter. The input side of the DC-DC converter module is connected to the output terminal of the new energy vehicle power battery, and the output side of the DC-DC converter module is connected to the input terminal of the new energy vehicle electric drive inverter, so as to transmit the output voltage of the new energy vehicle power battery to the input side of the new energy vehicle electric drive inverter by stepping down the voltage.

[0006] Optionally, the DC-to-DC module is used to control the output voltage of the DC-to-DC module in real time by detecting the speed of the new energy vehicle's power motor and the input current of the new energy vehicle's electric drive inverter, so as to realize that the input DC voltage of the new energy vehicle's electric drive inverter changes with the motor's operating conditions.

[0007] Optionally, the new energy vehicle electric drive inverter is used to adjust the output current of the new energy vehicle electric drive inverter according to the changes in motor speed and DC voltage on the input side of the new energy vehicle electric drive inverter, so as to control the motor torque.

[0008] Optionally, the DC-to-DC module includes a DC-DC buck converter composed of a non-isolated Buck circuit, and the new energy vehicle electric drive inverter includes a three-phase two-level inverter.

[0009] Optionally, the non-isolated Buck circuit includes a first switching transistor, a second switching transistor, a first input capacitor, an output capacitor, and a freewheeling inductor; one end of the first input capacitor is connected to the drain of the first switching transistor, the other end of the first input capacitor is connected to the source of the second switching transistor and one end of the output capacitor, the source of the first switching transistor is connected to the drain of the second switching transistor and one end of the freewheeling inductor, and the other end of the freewheeling inductor is connected to the other end of the output capacitor.

[0010] Optionally, the three-phase two-level inverter includes three sets of parallel bridge arms and a second input capacitor. The second input capacitor is connected in parallel with the three sets of parallel bridge arms. Each set of bridge arms includes two series-connected third switching transistors. The three-phase stator windings of the permanent magnet synchronous motor for new energy vehicles are connected between each pair of series-connected third switching transistors.

[0011] Optionally, one end of the output capacitor is connected to one end of the second input capacitor, and the other end of the output capacitor is connected to the other end of the second input capacitor.

[0012] Optionally, one end of the first input capacitor is also connected to the positive output terminal of the new energy vehicle power battery, and the other end of the first input capacitor is also connected to the negative output terminal of the new energy vehicle power battery.

[0013] Optionally, the first switch, the second switch, and the third switch are all power switches.

[0014] The second aspect of this application provides a new energy vehicle, including the electric drive main power circuit as described in the first aspect of this application.

[0015] As can be seen, the electric drive main power circuit applied to new energy vehicles in this application embodiment, or a new energy vehicle including such an electric drive main power circuit, comprises a DC-DC converter and a new energy vehicle electric drive inverter. The input side of the DC-DC converter is connected to the output terminal of the new energy vehicle's power battery, and the output side of the DC-DC converter is connected to the input terminal of the new energy vehicle's electric drive inverter, so as to transmit the output voltage of the new energy vehicle's power battery to the input side of the new energy vehicle's electric drive inverter through voltage reduction. By adding a DC-DC converter to the front stage of the new energy vehicle's electric drive inverter for voltage reduction, the input voltage of the electric drive inverter can be adjusted according to the actual operating conditions of the new energy vehicle, thereby adjusting the losses of the electric drive inverter and the overall efficiency of the vehicle's power control system. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the structure of an electric drive main power circuit provided in one embodiment of this application is shown;

[0018] Figure 2 A schematic diagram of the structure of a DC-DC converter module provided in one embodiment of this application is shown;

[0019] Figure 3 This paper shows a schematic diagram of the structure of a new energy vehicle electric drive inverter according to an embodiment of this application;

[0020] Figure 4 A schematic diagram of the structure of an electric drive main power circuit provided in another embodiment of this application is shown. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0022] Please refer to Figure 1This document illustrates a schematic diagram of an electric drive main power circuit according to an embodiment of this application. The electric drive main power circuit 1 includes a DC-DC converter 10 and a new energy vehicle electric drive inverter 20. The input side of the DC-DC converter 10 is connected to the output terminal of the new energy vehicle power battery, and the output side of the DC-DC converter 10 is connected to the input terminal of the new energy vehicle electric drive inverter 20, so as to transmit the output voltage of the new energy vehicle power battery to the input side of the new energy vehicle electric drive inverter 20 by stepping down the voltage.

[0023] The DC-to-DC module 10 is used to control the output voltage of the DC-to-DC module in real time by detecting the speed of the new energy vehicle's power motor and the input current of the new energy vehicle's electric drive inverter 20, so as to realize that the input DC voltage of the new energy vehicle's electric drive inverter changes with the motor's operating conditions.

[0024] The operating curve range of the new energy vehicle's power motor will change with the change of the DC side voltage of the electric drive inverter. The new energy vehicle electric drive inverter is used to adjust the output current of the new energy vehicle electric drive inverter according to the changes in motor speed and the DC voltage on the input side of the new energy vehicle electric drive inverter, so as to control the motor torque.

[0025] Specifically, the new energy vehicle electric drive inverter is used to calculate the minimum input voltage of the new energy vehicle electric drive inverter at different motor speeds based on the relationship between the DC side voltage of the new energy vehicle electric drive inverter and the motor speed, under the condition that the input current of the new energy vehicle electric drive inverter does not exceed the specified maximum current, so as to adjust the output current of the new energy vehicle electric drive inverter according to the minimum input voltage to control the motor torque.

[0026] The relationship between the DC-side voltage of the electric drive inverter and the motor speed of the new energy vehicle is obtained by transforming the efficiency objective function of the electric drive main power circuit according to a mathematical method for achieving efficiency optimization.

[0027] Specifically, the efficiency objective function is transformed according to a mathematical method for achieving efficiency optimization. That is, the input voltage of the new energy vehicle electric drive inverter is used as the independent variable, and the derivative of the efficiency objective function is calculated. The value of the input voltage of the new energy vehicle electric drive inverter when the derivative is 0 is determined as the relationship between the DC side voltage of the new energy vehicle electric drive inverter and the motor speed.

[0028] The specified maximum current is determined based on the actual speed and torque of the new energy vehicle motor, the input voltage of the new energy vehicle electric drive inverter, the rated torque of the new energy vehicle motor, the conduction loss of the electric drive inverter of the new energy vehicle motor under rated torque, the rated voltage of the new energy vehicle motor, and the switching loss of the electric drive inverter of the new energy vehicle motor under rated torque and rated voltage.

[0029] In one specific embodiment of this application, the specified maximum current satisfies:

[0030]

[0031] in, For the specified maximum current, This refers to the actual rotational speed of the electric motor in the new energy vehicle. This refers to the actual torque of the electric motor in the new energy vehicle. This refers to the input voltage of the electric drive inverter for the new energy vehicle. The rated torque of the electric motor in the new energy vehicle is... This refers to the conduction loss of the electric drive inverter for the new energy vehicle motor under rated torque. The rated voltage of the electric motor of the new energy vehicle. The switching losses of the electric drive inverter for the new energy vehicle motor under rated torque and rated voltage are given. This is an empirical constant, usually taken as 1.

[0032] The efficiency objective function is determined based on the rated torque and actual torque of the new energy vehicle motor, the conduction loss of the electric drive inverter of the new energy vehicle motor under rated torque, the switching loss of the electric drive inverter of the new energy vehicle motor under rated torque and rated voltage, the input voltage and rated voltage of the new energy vehicle electric drive inverter, the constant ratio of the total loss of the DC-to-DC module to the input current of the new energy vehicle electric drive inverter, and the specified maximum current.

[0033] In one specific embodiment of this application, the efficiency objective function is:

[0034]

[0035] in, For the efficiency objective function, and These are the rated torque and actual torque of the electric motor in the new energy vehicle, respectively. This refers to the conduction loss of the electric drive inverter for the new energy vehicle motor under rated torque. The switching losses of the electric drive inverter for the new energy vehicle motor under rated torque and rated voltage are given. and These are the input voltage and rated voltage of the electric drive inverter for the new energy vehicle, respectively. This is the ratio of the total loss of the DC-to-DC module to the constant of the input current of the new energy vehicle electric drive inverter. This refers to the actual torque of the electric motor in the new energy vehicle. This is an empirical constant, usually taken as 1.

[0036] For example, different values ​​such as 0.8, 1, 1.2, and 1.5 can be used, which need to be determined according to the specific type of new energy vehicle. More specifically, it needs to be determined according to the specific parameters of each circuit component in the electric drive main power circuit of the new energy vehicle, and no restrictions are made here.

[0037] As can be seen, the method of adding a DC-to-DC converter to the front stage of the electric drive inverter in this embodiment of the application can adjust the input voltage of the electric drive inverter according to the actual operating conditions of the new energy vehicle, thereby adjusting the losses of the electric drive inverter and the overall efficiency of the vehicle power control system.

[0038] Please refer to Figure 2 This illustration shows a schematic diagram of a DC-to-DC module according to an embodiment of this application. The DC-to-DC module 10 includes a DC-to-DC buck converter composed of a non-isolated Buck circuit, wherein the non-isolated Buck circuit includes a first switching transistor. Second switching transistor First input capacitor Output capacitor freewheeling inductor The first input capacitor One end is connected to the first switching transistor The drain connection, the first input capacitor The other end is connected to the second switching transistor The source and output capacitor One end is connected to the first switching transistor. The source of the second switch The drain and the freewheeling inductor One end is connected to the freewheeling inductor. The other end is connected to the output capacitor The other end is connected.

[0039] The non-isolated Buck circuit is a two-port network, and the first input capacitor... One end is also connected to the positive output terminal of the new energy vehicle power battery, and the first input capacitor The other end is also connected to the negative output terminal of the new energy vehicle power battery.

[0040] As can be seen, by adding a non-isolated Buck circuit to the front stage of the electric drive inverter in this embodiment, the efficiency of converting the electrical power output from the power battery to the mechanical power output from the motor is increased while ensuring the charging efficiency of the new energy vehicle. Compared with the traditional method of changing the series and parallel connection of the batteries, this method can achieve stepless adjustment of the input voltage of the electric drive inverter, reduce the probability of battery failure, and improve the reliability of power supply. Compared with the front-stage Boost converter circuit scheme, this method provides a higher voltage level for the power battery of the new energy vehicle, thereby ensuring the charging efficiency of the battery.

[0041] Please refer to Figure 3 This document illustrates a schematic diagram of a new energy vehicle electric drive inverter according to an embodiment of this application. The new energy vehicle electric drive inverter 20 includes a three-phase two-level inverter, which comprises three sets of parallel bridge arms and a second input capacitor. The second input capacitor The bridge arm is connected in parallel with the three sets of parallel bridge arms. Each set of bridge arms includes two third switching tubes connected in series. The middle of each pair of third switching tubes connected in series is connected to the three-phase stator winding of the new energy vehicle power permanent magnet synchronous motor.

[0042] Specifically, the first group of bridge arms is controlled by the third switch. and the third switching transistor The bridge is connected in series, and the second group of bridge arms is composed of the third switch. and the third switching transistor The bridge is composed of series connections, and the third group of bridge arms consists of the third switch. and the third switching transistor Composed of series connections.

[0043] Please refer to Figure 4 This illustration shows a schematic diagram of the main power circuit for electric drive provided in another embodiment of this application. The main power circuit 1 for electric drive includes a DC-DC converter 10 and a new energy vehicle electric drive inverter 20. The input side of the DC-DC converter 10 is connected to the output terminal of the new energy vehicle power battery, and the output side of the DC-DC converter 10 is connected to the input terminal of the new energy vehicle electric drive inverter 20, so as to transmit the output voltage of the new energy vehicle power battery to the input side of the new energy vehicle electric drive inverter 20 by stepping down the voltage.

[0044] The DC-to-DC module 10 is used to control the output voltage of the DC-to-DC module in real time by detecting the speed of the new energy vehicle's power motor and the input current of the new energy vehicle's electric drive inverter 20, so as to realize that the input DC voltage of the new energy vehicle's electric drive inverter changes with the motor's operating conditions.

[0045] The operating curve range of the new energy vehicle's power motor will change with the change of the DC side voltage of the electric drive inverter. The new energy vehicle electric drive inverter is used to adjust the output current of the new energy vehicle electric drive inverter according to the changes in motor speed and the DC voltage on the input side of the new energy vehicle electric drive inverter, so as to control the motor torque.

[0046] The DC-to-DC module 10 includes a DC-DC buck converter composed of a non-isolated Buck circuit, wherein the non-isolated Buck circuit includes a first switching transistor. Second switching transistor First input capacitor Output capacitor freewheeling inductor The first input capacitor One end is connected to the first switching transistor The drain connection, the first input capacitor The other end is connected to the second switching transistor The source and output capacitor One end is connected to the first switching transistor. The source of the second switch The drain and the freewheeling inductor One end is connected to the freewheeling inductor. The other end is connected to the output capacitor The other end is connected.

[0047] The non-isolated Buck circuit is a two-port network, and the first input capacitor... One end is also connected to the positive output terminal of the new energy vehicle power battery, and the first input capacitor The other end is also connected to the negative output terminal of the new energy vehicle power battery.

[0048] The new energy vehicle electric drive inverter 20 includes a three-phase two-level inverter, which comprises three sets of parallel bridge arms and a second input capacitor. The second input capacitor The bridge arm is connected in parallel with the three sets of parallel bridge arms. Each set of bridge arms includes two third switching tubes connected in series. The middle of each pair of third switching tubes connected in series is connected to the three-phase stator winding of the new energy vehicle power permanent magnet synchronous motor.

[0049] Specifically, the first group of bridge arms is controlled by the third switch. and the third switching transistor The bridge is connected in series, and the second group of bridge arms is composed of the third switch. and the third switching transistor The bridge is composed of series connections, and the third group of bridge arms consists of the third switch. and the third switching transistor Composed of series connections.

[0050] Wherein, the output capacitor One end is connected to the second input capacitor One end is connected to the output capacitor. The other end is connected to the second input capacitor The other end is connected.

[0051] Wherein, the first switching transistor The second switching transistor The third switching transistor All of them are power switching transistors.

[0052] The second aspect of this application provides a new energy vehicle, including the electric drive main power circuit as described in the first aspect of this application.

[0053] It should be noted that the new energy vehicle in this application embodiment can be a traditional 400V voltage platform, an 800V voltage platform that is currently under development, or other voltage platforms in the future, which are not limited here.

[0054] It is understood that the specific examples in this application are only intended to help those skilled in the art better understand the implementation methods of this application, and are not intended to limit the scope of the invention.

[0055] It is understood that in the various embodiments of this application, the sequence number of each process does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not limit the implementation process of the embodiments of this application in any way.

[0056] It is understood that the various implementation methods described in this application can be implemented individually or in combination, and the implementation methods in this application are not limited in this respect.

[0057] Unless otherwise stated, all technical and scientific terms used in the embodiments of this application have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this application includes any and all combinations of one or more of the associated listed items. The singular forms "a," "the," and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0058] The above are merely specific embodiments of this application, but the scope of protection of this invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. An electric drive main power circuit applied to a new energy vehicle, characterized in that, The electric drive main power circuit comprises a DC-DC module and a new energy vehicle electric drive inverter, an output end of a new energy vehicle power battery is connected to an input side of the DC-DC module, and an output side of the DC-DC module is connected to an input end of the new energy vehicle electric drive inverter, so that the output voltage of the new energy vehicle power battery is transmitted to the input side of the new energy vehicle electric drive inverter through voltage reduction, the DC-DC module comprises a non-isolated Buck circuit composed of a DC voltage reduction converter, the non-isolated Buck circuit comprises a first switch tube, a second switch tube, a first input capacitor, an output capacitor and a freewheeling inductor, one end of the first input capacitor is connected to the drain of the first switch tube, the other end of the first input capacitor is connected to the source of the second switch tube and one end of the output capacitor, the source of the first switch tube is connected to the drain of the second switch tube and one end of the freewheeling inductor, the other end of the freewheeling inductor is connected to the other end of the output capacitor, and the first switch tube and the second switch tube are power switch tubes. The new energy vehicle electric drive inverter is used to calculate the minimum input voltage of the new energy vehicle electric drive inverter at different motor speeds according to the relationship between the DC side voltage of the new energy vehicle electric drive inverter and the motor speed under the condition that the input current of the new energy vehicle electric drive inverter does not exceed the specified maximum current, to adjust the output current of the new energy vehicle electric drive inverter according to the minimum input voltage, and to control the motor torque, and the specified maximum current satisfies: wherein, is a specified maximum current, is an actual rotational speed of the new energy automobile motor, is an actual torque of the new energy automobile motor, is an input voltage of the electric drive inverter of the new energy automobile, is a rated torque of the new energy automobile motor, is a conduction loss of the electric drive inverter of the new energy automobile motor at the rated torque, is a rated voltage of the new energy automobile motor, is a switching loss of the electric drive inverter of the new energy automobile motor at the rated torque and the rated voltage, is an empirical constant.

2. The electric drive main power circuit according to claim 1, characterized in that, The DC-DC module is used to control the output voltage of the DC-DC module in real time by detecting the motor speed of the new energy vehicle power motor and the input current of the new energy vehicle electric drive inverter, so that the DC voltage of the input side of the new energy vehicle electric drive inverter changes with the change of the motor working condition.

3. The electric drive main power circuit of claim 1, wherein, The new energy vehicle electric drive inverter is used to adjust the output current of the new energy vehicle electric drive inverter according to the change of the motor speed and the DC voltage of the input side of the new energy vehicle electric drive inverter, so as to control the motor torque.

4. The electrically driven main power circuit according to any one of claims 1 to 3, characterized in that The new energy vehicle electric drive inverter comprises a three-phase two-level inverter.

5. The electric drive main power circuit of claim 4, wherein, The three-phase two-level inverter comprises three groups of parallel bridge arms and a second input capacitor, the second input capacitor is connected in parallel with the three groups of parallel bridge arms, each group of bridge arms comprises two third switch tubes connected in series, and the three-phase stator windings of the new energy vehicle power permanent magnet synchronous motor are connected to the middle of each two third switch tubes in series.

6. The electric drive main power circuit of claim 5, wherein, One end of the output capacitor is connected to one end of the second input capacitor, and the other end of the output capacitor is connected to the other end of the second input capacitor.

7. The electrically driven main power circuit according to any of claims 4-6, characterized in that, One end of the first input capacitor is also connected to the positive output end of the new energy vehicle power battery, and the other end of the first input capacitor is also connected to the negative output end of the new energy vehicle power battery.

8. The electrically driven main power circuit according to claim 5 or 6, characterized in that, The first switch tube, the second switch tube and the third switch tube are power switch tubes.

9. A new energy vehicle, characterized in that, The electric drive main power circuit comprises the electric drive main power circuit according to any one of claims 1-8.

Images