阅读说明：本技术 车辆用逆变器系统 (Inverter system for vehicle ) 是由 金凡植 于 2018-11-30 设计创作，主要内容包括：本发明提供了一种车辆用逆变器系统。该系统包括：能量存储装置,配置为存储电能；以及第一逆变器,包括多个第一开关器件并将能量存储装置中存储的能量转换为AC电力。第二逆变器包括多个与第一开关器件的类型不同的第二开关器件,并且与第一逆变器并联连接到能量存储装置。第二逆变器将能量存储装置中存储的能量转换成AC电力。电动机由第一逆变器和第二逆变器转换的AC电力驱动。控制器基于电动机的所需输出功率生成PWM信号,并且通过将生成的PWM信号输入到第一逆变器和第二逆变器中的至少一者或多者来操作电动机。(The invention provides an inverter system for a vehicle. The system comprises: an energy storage device configured to store electrical energy; and a first inverter including a plurality of first switching devices and converting energy stored in the energy storage device into AC power. The second inverter includes a plurality of second switching devices of a type different from that of the first switching devices, and is connected to the energy storage device in parallel with the first inverter. The second inverter converts energy stored in the energy storage device into AC power. The motor is driven by the AC power converted by the first inverter and the second inverter. The controller generates a PWM signal based on a required output power of the motor, and operates the motor by inputting the generated PWM signal to at least one or more of the first inverter and the second inverter.)

1. An inverter system for a vehicle, comprising:

an energy storage device configured to store electrical energy;

a first inverter including a plurality of first switching devices and configured to convert energy stored in the energy storage device into alternating-current power;

a second inverter including a plurality of second switching devices of a type different from that of the first switching devices, connected to the energy storage apparatus in parallel with the first inverter, and configured to convert energy stored in the energy storage apparatus into alternating-current power;

a motor driven by the alternating-current power converted by the first inverter and the second inverter; and

a controller configured to generate a pulse width modulation signal based on a required output power of the motor, and configured to operate the motor by inputting the generated pulse width modulation signal to at least one of the first inverter or the second inverter.

2. The inverter system of claim 1, wherein the first switching device is a silicon carbide field effect transistor and the second switching device is a silicon insulated gate bipolar transistor.

3. The inverter system according to claim 2, wherein the controller is configured to drive the first inverter by inputting a pulse width modulation signal to the first switching device when a required output power of the motor is less than a predetermined reference.

4. The inverter system according to claim 2, wherein the controller is configured to drive the second inverter by inputting a pulse width modulation signal to the second switching device when a required output power of the motor is greater than a predetermined reference.

5. The inverter system according to claim 2, wherein the controller is configured to drive the first inverter and the second inverter by generating a first pulse width modulation signal and a second pulse width modulation signal and inputting the first pulse width modulation signal to the first switching device and the second pulse width modulation signal to the second switching device when a required output power of the motor is greater than a predetermined reference.

6. The inverter system of claim 5, wherein the controller is configured to input the first pulse width modulated signal to the first switching device and the second pulse width modulated signal to the second switching device, turn on the second switching device a predetermined time later than the first switching device, and turn off the second switching device the predetermined time later than the first switching device.

7. The inverter system of claim 5, wherein the controller is configured to input the second pulse width modulated signal to the first switching device and the first pulse width modulated signal to the second switching device, turn on the first switching device a predetermined time later than the second switching device, and turn off the first switching device the predetermined time later than the second switching device.

8. The inverter system of claim 6, wherein the predetermined time is 1/4 of a period of the first pulse width modulated signal.

9. The inverter system of claim 7, wherein the predetermined time is 1/4 of a period of the first pulse width modulated signal.

10. The inverter system of claim 1, wherein switching and conduction losses of the first inverter are less than switching and conduction losses of the second inverter.

11. The inverter system according to claim 1, wherein a rated output power of the first inverter for driving the motor is smaller than a rated output power of the second inverter for driving the motor.

12. The inverter system according to claim 1, wherein the motor is a single motor that operates by selectively receiving the first inverter-converted electric power or the second inverter-converted electric power according to a required output power of the motor, or by simultaneously receiving the first inverter-converted electric power and the second inverter-converted electric power.

13. The inverter system according to claim 1, wherein the motor includes a first motor driven by the electric power converted by the first inverter and a second motor driven by the electric power converted by the second inverter.

Technical Field

The present disclosure relates to an inverter system for a vehicle, and more particularly, to an inverter system for a vehicle that improves efficiency and output by driving an inverter according to required output power of the vehicle.

Background

Recently, technologies related to environmentally friendly vehicles using electric energy as power for driving the vehicles have been actively developed to cope with air pollution and oil exhaustion. Environmentally friendly vehicles include hybrid electric vehicles, fuel cell electric vehicles, and electric vehicles.

Meanwhile, as shown in fig. 1, according to the related art automobile inverter system for realizing high output, the motor is driven by connecting a plurality of switching elements S1-S6 in parallel to realize high output. However, although high output can be achieved by connecting a plurality of switching elements in parallel to the motor in the inverter system of the related art, the overall fuel efficiency of the vehicle may be reduced due to excessive switching loss and conduction loss of the switching elements in an eco-friendly driving mode in which the motor requires relatively small output power.

Recently, in order to solve this problem, research has been actively conducted relating to a silicon carbide field effect transistor (SiC-FET) having a minimum loss in an eco-friendly driving mode in which a motor requires relatively small output power. However, SiC-FETs are expensive compared to Si-IGBTs and have poor heat dissipation capability due to their small size, and thus there is a limitation in configuring an inverter by connecting a plurality of SiC-FETs. Therefore, there is a need for an inverter system that can take advantage of the advantages of both Si-IGBTs and SiC-FETs.

Disclosure of Invention

The present disclosure provides an inverter system for a vehicle that drives a motor by generating a Pulse Width Modulation (PWM) signal based on an output power of the motor and then inputting the PWM signal to at least one or more of a first inverter and a second inverter, thereby improving efficiency and output of the vehicle.

According to an aspect of the present disclosure, an inverter system for a vehicle may include: an energy storage device configured to store electrical energy; a first inverter having a plurality of first switching devices and configured to convert energy stored in an energy storage apparatus into Alternating Current (AC) power; a second inverter having a plurality of second switching devices of a type different from that of the first switching devices, and connectable to the energy storage apparatus in parallel with the first inverter, and configured to convert energy stored in the energy storage apparatus into AC power; a motor driven by the AC power converted by the first inverter and the second inverter; and a controller configured to generate a Pulse Width Modulation (PWM) signal based on a required output power of the motor, and configured to operate the motor by inputting the generated PWM signal to at least one or more of the first inverter and the second inverter.

The first switching device may be a silicon carbide field effect transistor (SiC-FET) and the second switching device may be a silicon insulated gate bipolar transistor (Si-IGBT). The controller may be configured to drive the first inverter by inputting the PWM signal to the first switching device when a required output power of the motor is less than a predetermined reference. The controller may be configured to drive the second inverter by inputting the PWM signal to the second switching device when the required output power of the motor is greater than a predetermined reference.

When the required output power of the motor is greater than the predetermined reference, the controller may be configured to drive the first inverter and the second inverter by generating a first PWM signal and a second PWM signal and inputting the first PWM signal to the first switching device and the second PWM signal to the second switching device. The controller may be configured to input the first PWM signal to the first switching device and the second PWM signal to the second switching device, turn on the second switching device later than the first switching device by a predetermined time, and turn off the second switching device later than the first switching device by a predetermined time.

The controller may be configured to input the second PWM signal to the first switching device and the first PWM signal to the second switching device, turn on the first switching device later than the second switching device by a predetermined time, and turn off the first switching device later than the second switching device by a predetermined time. The predetermined time may be 1/4 of the period of the first PWM signal. The predetermined time may be 1/4 of the period of the first PWM signal. The switching loss and the conduction loss of the first inverter may be smaller than the switching loss and the conduction loss of the second inverter. The rated output power of the first inverter for driving the motor may be smaller than the rated output power of the second inverter for driving the motor.

The motor may be a single motor that operates by selectively receiving the converted power of the first inverter or the converted power of the second inverter according to a required output power of the motor, or by simultaneously receiving the converted power of the first inverter and the converted power of the second inverter. The motor may include a first motor driven by the electric power converted by the first inverter and a second motor driven by the electric power converted by the second inverter.

According to the present disclosure, the motor may be driven by generating a PWM signal based on the output power of the motor and then inputting the PWM signal to at least one or more of the first inverter and the second inverter, thereby improving the efficiency and output of the vehicle. Further, when the required output power of the motor is greater than a predetermined level, it is possible to reduce a Direct Current (DC) -link current ripple of the inverter system by driving the first and second inverters by inputting PWM signals having different on/off time points to the first and second switching devices, and thus to reduce the manufacturing cost.

Drawings

The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

fig. 1 is a diagram showing a related art inverter system;

fig. 2 is a diagram illustrating an inverter system for a vehicle according to an exemplary embodiment of the present disclosure;

fig. 3 is a graph illustrating first and second PWM signals input to first and second inverters when a required output power of a motor is greater than a predetermined reference in an inverter system for a vehicle according to an exemplary embodiment of the present disclosure;

fig. 4 is a graph showing a current ripple value of a DC link capacitor when a first PWM signal and a second PWM signal are not shifted in an inverter system for a vehicle according to an exemplary embodiment of the present disclosure;

fig. 5 is a graph showing a current ripple value of a DC link capacitor when a first PWM signal and a second PWM signal are shifted in an inverter system for a vehicle according to an exemplary embodiment of the present disclosure; and is

Fig. 6 is a diagram illustrating an inverter system according to another exemplary embodiment of the present disclosure.

Detailed Description

It should be understood that the term "vehicle" or "vehicular" or other similar terms as used herein include automobiles in general, such as passenger vehicles including Sport Utility Vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle having two or more power sources, for example, a vehicle having gasoline power and electric power.

While the exemplary embodiments are described as using multiple units to implement the exemplary operations, it will be understood that the exemplary operations may also be implemented by one or more modules. Further, it is understood that the term controller/control unit refers to a hardware device that includes a memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute the modules to perform one or more operations described further below.

Further, the control logic of the present invention may be embodied as a non-transitory computer readable medium containing executable program instructions executed by a processor, controller/control unit, or the like. Examples of the computer readable medium include, but are not limited to, a ROM, a RAM, a Compact Disc (CD) -ROM, a magnetic tape, a floppy disk, a flash disk, a smart card, and an optical data storage device. The computer-readable recording medium CAN also be distributed over network-coupled computer systems so that the computer-readable medium is stored and executed in a decentralized manner, such as through a telematics server or a Controller Area Network (CAN).

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The term "about" as used herein is understood to be within the normal tolerance of the art, e.g., within 2 standard deviations of the mean, unless otherwise indicated or apparent from the context. "about" can be understood as being within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the stated value. Unless otherwise clear from the context, all numbers provided herein are modified by the term "about".

An inverter system for a vehicle according to an exemplary embodiment of the present disclosure is described below with reference to the accompanying drawings.

Fig. 2 is a diagram illustrating a vehicle inverter system according to the present disclosure. As shown in fig. 2, the inverter system for a vehicle according to the present disclosure may include an energy storage device 100, a first inverter 200, a second inverter 300, a motor M, and a controller 400. The detailed configuration of the inverter system for a vehicle according to the present disclosure is described in detail below.

The energy storage device 100 may be configured to store electrical energy and provide electrical energy for driving the electric motor M. According to an exemplary embodiment, energy storage device 100 may be a battery that stores and provides electrical energy for driving an electric motor in a vehicle. However, this is only an exemplary embodiment, and various devices including a super capacitor may be used as the energy storage device of the present disclosure as long as they can store and provide electric energy for driving the motor in the vehicle.

First inverter 200 may include a plurality of first switching devices 210 and be configured to convert energy stored in energy storage device 100 into AC power. As shown in fig. 2, the first switching devices 210 are connected in parallel with each other, and the output terminals of the parallel-connected first switching devices 210 may be connected to the phases of the motor. The first switching device 210 of the first inverter 200 may be configured to convert DC power transmitted from the energy storage device 100 into AC power, and the conversion of DC power into AC power by the inverter is well known in the art and thus will not be described in detail.

The first switching device may be a silicon carbide field effect transistor (SiC-FET). In the present disclosure, a SiC-FET may be used as the first switching device because the switching loss and the conduction loss of the SiC-FET at low load are much smaller than those of the Si-IGBT. In other words, when the required output power of the motor is small, the motor M can be driven by the first inverter 200 including the SiC-FET to reduce the switching loss and the conduction loss, so that the overall fuel efficiency of the vehicle can be improved.

The switching loss and the conduction loss of the first inverter 200 composed of the first switching devices 210 may be less than those of the second inverter 300, which will be described below. Further, the rated output power of the first inverter 200 for driving the motor may be smaller than the rated output power of the second inverter 300 for driving the motor. The second inverter 300 may include a plurality of second switching devices 310 of a different type from the first switching devices 210, and is configured to convert energy stored in the energy storage apparatus 100 into AC power. As shown in fig. 2, the second switching devices 310 are connected in parallel with each other, and the output terminals of the parallel-connected second switching devices 310 may be connected to the phases of the motor. Second inverter 300 may be connected to energy storage device 100 in parallel with first inverter 200.

The second switching device 310 of the second inverter 300 may be configured to convert DC power transmitted from the energy storage device 100 into AC power by being turned on/off by a controller 400, which will be described below. The conversion of DC power to AC power by an inverter is well known in the art and therefore will not be described in detail. The second switching device 310 may be a silicon insulated gate bipolar transistor (Si-IGBT). High output can be achieved by connecting the Si-IGBT as the second switching device 310 in parallel and driving the motor M via the second inverter 300 including the Si-IGBT in a high output mode requiring large output power of the motor.

The motor M may be driven by the AC power converted by the first inverter 200 and the second inverter 300. In other words, motor M may be driven by electric power supplied through first inverter 200 and second inverter 300, thereby being able to drive the vehicle. The controller 400 may be configured to generate a Pulse Width Modulation (PWM) signal based on a required output power of the motor M, and may be configured to operate the motor M by inputting the generated PWM signal to at least one or more of the first inverter 200 and the second inverter 300. The required output power of the motor M may be the required output power of the vehicle. In other words, controller 400 may be configured to drive motor M by driving at least one or more of first inverter 200 and second inverter 300, depending on whether the vehicle requires an eco-drive mode in which relatively low output power or a sport mode or high output mode in which relatively high output power is required.

Specifically, when the required output power of the motor M is less than a predetermined reference, that is, in an eco-friendly driving mode in which the vehicle requires relatively low output power, the controller 400 may be configured to drive the first inverter 200 by inputting a PWM signal to the first switching device 210. In other words, when the required output power of the motor M is less than the predetermined reference, the controller 400 may be configured to reduce switching loss and conduction loss by causing the electric energy supplied from the energy storage device 100 to be converted into AC power by the first inverter 200 and then transmitted to the motor M, and thus may improve the fuel efficiency of the vehicle.

Further, when the required output power of the motor M is greater than a predetermined reference, that is, in a sport mode or a high output mode in which the vehicle requires relatively high output power, the controller 400 may be configured to drive the second inverter 300 by inputting the PWM signal to the second switching device 310. In other words, when the required output power of the motor M is greater than the predetermined reference, the controller 400 may achieve a high output by causing the electric energy supplied from the energy storage device 100 to be converted into AC power by the second inverter 300 and then transmitted to the motor M.

Further, when the required output power of the motor M is greater than a predetermined reference, that is, in a sport mode or a high output mode in which the vehicle requires relatively high output power, the controller 400 may be configured to drive the first and second inverters 200 and 300 by generating the first and second PWM signals and then inputting the first PWM signal to the first switching device 310 and the second PWM signal to the second switching device 310. In other words, when the required output power of the motor M is greater than the predetermined reference, the controller 400 may achieve a high output by causing the electric energy supplied from the energy storage device 100 to be converted into AC power by the first inverter 200 and the second inverter 300 and then transmitted to the motor M.

Referring to fig. 3 to describe the first PWM signal and the second PWM signal in detail, the second PWM signal may be turned on later than the first PWM signal by a predetermined time and may be turned off later than the first PWM signal by a predetermined time. According to an exemplary embodiment, the predetermined time may be 1/4 of the period of the first PWM signal. In other words, assuming that the period of the first PWM signal according to the exemplary embodiment is 'a', as shown in fig. 3, the second PWM signal may be turned on later by 0.25a (1/4 of the period of the first PWM signal) than the turn-on of the first PWM signal, and may be turned off later by 0.25a (1/4 of the period of the first PWM signal) than the turn-off of the first PWM signal. Further, although not shown in the drawings, according to another exemplary embodiment, the first PWM signal may be turned on later than the second PWM signal by a predetermined time, and the first PWM signal may be turned off later than the second PWM signal. Depending on the exemplary embodiment, the predetermined time may be 1/4 of the period of the first PWM signal.

As described above, when the required output power of the motor M is greater than the predetermined reference, the controller 400 may be configured to generate the first PWM signal and the second PWM signal and then input the first PWM signal to the first switching device 210 and the second PWM signal to the second switching device 310, turn on the second switching device 310 later than the first switching device 210 by a predetermined time and turn off the second switching device 310 later than the first switching device 210 by a predetermined time. Further, according to another exemplary embodiment, when the required output power of the motor M is greater than the predetermined reference, the controller 400 may be configured to input the second PWM signal to the first switching device 210 and the first PWM signal to the second switching device 310, turn on the first switching device 210 later by a predetermined time than the second switching device 310 and turn off the first switching device 210 later by a predetermined time than the second switching device 310.

According to the present disclosure, when the required output power of the motor M is greater than the predetermined reference, the controller 400 may be configured to drive the first and second inverters 200 and 300 by generating the first and second PWM signals having different on/off time points and then inputting the signals to the first and second switching devices 210 and 310, whereby current ripples generated by the operation of the inverters may be reduced. Therefore, the material cost of the capacitor C between the energy storage device 100 and the first inverter 200 and the second inverter 300 can be reduced.

In particular, referring to fig. 2, in the inverter system for a vehicle according to the present disclosure, a capacitor C connected in parallel with the energy storage device 100 may be disposed between the energy storage device 100 and the first and second inverters 200 and 300. The capacitor C prevents a current ripple component from being transferred to the energy storage device 100 by absorbing current ripples generated by the operations of the first inverter 200 and the second inverter 300. Referring to fig. 4 and 5, according to the present disclosure, since the controller 400 drives the first inverter 200 and the second inverter 300 in the above-described manner, the magnitude of the current ripple may be further reduced as compared to inputting the first PWM signal and the second PWM signal to the first inverter 200 and the second inverter 300 without a shift, and thus, the material cost of the capacitor C absorbing the current ripple component may be reduced.

Meanwhile, as shown in fig. 2, the motor M according to an exemplary embodiment of the present disclosure may be a single motor that selectively receives the power converted by the first inverter 200 or the power converted by the second inverter 300 through the controller 400 according to a required output power of the motor, or operates by simultaneously receiving the power converted by the first inverter 200 and the power converted by the second inverter 300. Specifically, when the motor M is a three-phase motor according to an exemplary embodiment, as shown in fig. 2, the output terminals of the first inverter 200 and the second inverter 300 may be commonly connected to the phases a, b, and c of the motor M, respectively. When the required output power of the motor is less than the predetermined reference, the controller 400 may be configured to drive the motor M by operating the first switching device 210 to drive the first inverter 200. Further, when the required output power of the motor is greater than the predetermined reference, the controller 400 may be configured to drive the motor M by operating the second switching device 310 to drive the second inverter 300, or by operating the first switching device 210 and the second switching device 310 to drive the first inverter 200 and the second inverter 300.

On the other hand, as shown in fig. 6, according to another exemplary embodiment of the present disclosure, the motor may include a first motor 500 driven by the electric power converted by the first inverter 200 and a second motor 600 driven by the electric power converted by the second inverter 300. Specifically, as shown in fig. 6, when the motors include a first motor 500 and a second motor 600, the output terminal of the first inverter 200 may be connected to the phases a, b, and c of the first motor 500, respectively, and the output terminal of the second inverter 300 may be connected to the phases a, b, and c of the second motor 600, respectively. When the required output power of the motor is less than the predetermined reference, the controller 400 may be configured to drive the first motor 500 by operating the first switching device 210 to drive the first inverter 200. In particular, when the required output power of the motor is greater than a predetermined reference, the controller 400 may be configured to drive the second motor 600 by operating the second switching device 310 to drive the second inverter 300.

Further, although not shown in detail in the drawings, the inverter system for a vehicle according to the present disclosure may further include: an input voltmeter (not shown) configured to measure a voltage input from energy storage device 100 to first inverter 200 and second inverter 300; a voltage converter (not shown) configured to convert the voltage measured by the input voltmeter and input the converted voltage to the controller 400; an output current meter (not shown) configured to measure currents output from the first inverter 200 and the second inverter 300; and a current converter (not shown) configured to convert the current measured by the output current meter and input the converted current to the controller 400. In this configuration, voltage information data input to the inverter through the voltage converter and output current information data input through the current converter and output from the inverter may be used to operate the inverter under the control of the controller 400.