Inverter system for vehicle

Abstract

An inverter system for a vehicle, comprising: an energy storage device configured to store electric energy; a first inverter including a plurality of first switching elements and configured to convert the electric energy stored in the energy storage device into alternating current (AC) power; a second inverter including a plurality of second switching elements different from the plurality of first switching elements; a motor configured to be driven by receiving the AC power converted by the first inverter and the second inverter; current sensors respectively arranged between the first inverter and the motor and between the second inverter and the motor and configured to detect a current input to the motor; and a controller configured to generate a pulse width modulation (PWM) signal for controlling the drive of the motor.

Description

Technical Field

[0001] The present disclosure relates to an inverter system for a vehicle, and more particularly, to an inverter system for a vehicle capable of improving efficiency and output by driving an inverter according to a required output amount of a vehicle and thus allowing the vehicle to be driven according to a limp-home mode when an inverter fails. Background Art

[0002] Recently, as a response to air pollution and oil depletion crises, technologies related to environmentally friendly vehicles using electric energy as vehicle power are actively developed. Environmentally friendly vehicles include hybrid electric vehicles, fuel cell electric vehicles, electric vehicles, and the like.

[0003] refer to Figure 1 In a conventional inverter system for a vehicle for outputting high output, a plurality of switching elements S1 to S6 are connected in parallel to drive the motor for high output. However, in a conventional inverter system, high output can be obtained by connecting a plurality of switching elements in parallel to the motor, but in a fuel economy driving mode where the required output of the motor is relatively low, excessive switching loss and conduction loss occur in the switching elements, so that there is a limitation that the fuel efficiency of the vehicle is reduced as a whole. In addition, in a conventional inverter system for a vehicle, there is a limitation that limp home driving is not possible when a fault such as a disconnection occurs between the motor and the inverter. Summary of the invention

[0004] Therefore, the present disclosure has been made keeping in mind the above-mentioned problems arising in the related art, and the present disclosure aims to propose an inverter system for a vehicle, which is capable of improving the efficiency and output of the vehicle by differently controlling the timings at which the first inverter and the second inverter are turned on and off based on the output amount of the motor, and maintaining the drive of the vehicle by limp-home driving when a fault (such as a wire break, etc.) occurs between the motor and the first inverter or the second inverter.

[0005] According to an exemplary embodiment of the present disclosure, an inverter system for a vehicle includes: an energy storage device configured to store electric energy; a first inverter including a plurality of first switching elements and configured to convert the electric energy stored in the energy storage device into alternating current (AC) power; a second inverter including a plurality of second switching elements different from the plurality of first switching elements, connected to the energy storage device in parallel with the first inverter, and configured to convert the electric energy stored in the energy storage device into AC power; a motor configured to be driven by receiving the AC power converted by the first inverter and the second inverter; current sensors respectively disposed between the first inverter and the motor and between the second inverter and the motor, and configured to detect a current input to the motor; and a controller configured to generate a pulse width modulation (PWM) signal for controlling the driving of the motor, determine a fault occurrence position between the first inverter and the motor or between the second inverter and the motor based on the detected current, and control the motor to be driven by the first inverter or the second inverter according to the fault occurrence position.

[0006] When it is determined that a fault occurs between the first inverter and the motor, the controller may allow the motor to be driven by the second inverter, and when it is determined that a fault occurs between the second inverter and the motor, the controller may allow the motor to be driven by the first inverter.

[0007] When it is determined that no fault occurs between the first inverter and the second inverter and the motor, the controller may control operations of the first inverter and the second inverter based on a required output amount of the motor.

[0008] When the required output of the motor is less than a predetermined reference, the controller may control the plurality of first switching elements to drive the first inverter.

[0009] When the required output of the motor is greater than a predetermined reference, the controller may control the plurality of second switching elements to operate the second inverter.

[0010] When the required output of the motor is greater than a predetermined reference, the controller may input a first PWM signal obtained by converting the PWM signal to the first inverter to control the first switching elements to be turned on before the second switching elements and turned off after the second switching elements.

[0011] When the required output of the motor is greater than a predetermined reference, the controller may input a second PWM signal obtained by converting the PWM signal to the second inverter to control the second switching elements to be turned on after the first switching elements and turned off before the first switching elements.

[0012] Each of the plurality of first switching elements may be a silicon carbide-field effect transistor (SiC-FET) and each of the plurality of second switching elements may be a silicon-insulated gate bipolar transistor (IGBT).

[0013] 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.

[0014] The first inverter may have a rated output for driving the motor that is smaller than a rated output of the second inverter.

[0015] The motor may be a single motor that operates by selectively or simultaneously receiving electric power converted by the first inverter and the second inverter according to output required by the motor.

[0016] The electric motor may include a first electric motor driven by receiving electric power converted by the first inverter and a second electric motor driven by receiving electric power converted by the second inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0018] Figure 1 is a diagram showing a conventional inverter system according to the prior art;

[0019] Figure 2 is a diagram showing an inverter system for a vehicle according to one embodiment of the present disclosure;

[0020] Figure 3 is a flowchart showing a process of driving a motor by a first inverter or a second inverter according to a fault occurrence position between the first inverter and the second inverter and the motor in an inverter system for a vehicle according to one embodiment of the present disclosure;

[0021] Figure 4 is a diagram showing pulse width modulation (PWM) signals input to a first inverter and a second inverter when a required output of a motor is greater than a reference in an inverter system of a vehicle according to an embodiment of the present disclosure; and

[0022] Figure 5 is a diagram illustrating an inverter system for a vehicle according to another embodiment of the present disclosure. DETAILED DESCRIPTION

[0023] Hereinafter, an inverter system for a vehicle according to an exemplary embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0024] Figure 2 is a diagram showing an inverter system for a vehicle according to one embodiment of the present disclosure, Figure 3 is a flowchart showing a process of driving the motor by the first inverter or the second inverter according to a fault occurrence position between the first inverter and the second inverter and the motor, and Figure 4 is a diagram showing pulse width modulation (PWM) signals input to the first inverter and the second inverter when the required output of the motor is greater than a reference.

[0025] like Figure 2 As shown in FIG. 1 , an inverter system for a vehicle according to an embodiment of the present disclosure may include an energy storage device 100, a first inverter 200, a second inverter 300, a motor M, a controller 400, and a current sensor 500. Hereinafter, a detailed configuration of the inverter system for a vehicle according to the present disclosure will be described in detail.

[0026] The energy storage device 100 stores electric energy and can be used to provide electric energy for driving the motor M. According to the present embodiment, the energy storage device 100 may be a battery that stores and provides electric energy for driving the motor M of the vehicle. However, this is merely an example, and various devices including supercapacitors and the like may be used as the energy storage device of the present disclosure as long as they can be used to store and provide electric energy for driving the motor of the vehicle.

[0027] The first inverter 200 includes a plurality of first switching elements 210 and is used to convert the electric energy stored in the energy storage device 100 into alternating current (AC) power. Figure 2 As shown in FIG. 1 , a plurality of first switching elements 210 are connected in parallel to each other and a plurality of output terminals of the first switching elements 210 connected in parallel may be connected to respective phases a, b, and c of the motor M. In addition, the plurality of first switching elements 210 in the first inverter 200 may convert direct current (DC) power transmitted from the energy storage device 100 into AC power and converting DC power into AC power through an inverter is a well-known technology, so a detailed description thereof will be omitted.

[0028] Each of the plurality of first switching elements 210 may be a silicon carbide field effect transistor (SiC-FET). In the present disclosure, the reason for using SiC-FET as each of the plurality of first switching elements 210 is that SiC-FET has switching loss and conduction loss that are significantly lower than those of Si-insulated gate bipolar transistor (IGBT) under low load. That is, when the required output of the motor M is small, the motor M is driven by the first inverter 200 including the SiC-FET, so that the switching loss and conduction loss can be reduced and thus the overall fuel efficiency of the vehicle can be improved.

[0029] The first inverter 200 configured with the plurality of first switching elements 210 may have switching loss and conduction loss lower than those of the second inverter 300 to be described below. In addition, the first inverter 200 may have a rated output for driving the motor M that is lower than the rated output of the second inverter 300.

[0030] The second inverter 300 includes a plurality of second switching elements 310 of a different kind from the plurality of first switching elements 210 and may be used to convert the electric energy stored in the energy storage device 100 into AC power. Figure 2 As shown in , a plurality of first switching elements 310 are connected in parallel to each other and a plurality of output terminals of the parallel-connected first switching elements 310 may be connected to respective phases a, b, and c of the motor M. In addition, the second inverter 300 may be connected to the energy storage device 100 in a parallel relationship with the first inverter 200 .

[0031] In addition, the plurality of second switching elements 310 in the second inverter 300 may be turned on and off by the controller 400 to be described below to convert the DC power transmitted from the energy storage device 100 into AC power. Conversion from DC power to AC power by an inverter is a well-known technology, and thus a detailed description thereof will be omitted.

[0032] The second switching element 310 may be a silicon insulated gate bipolar transistor (Si-IGBT). In the present disclosure, a plurality of second switching elements 310 as Si-IGBTs are connected in parallel, and in a high output mode in which the required output of the motor M is high, the motor M is driven by the second inverter 300 including the Si-IGBT so that a high output can be output. For the convenience of description, in the following detailed description, it will be described by assuming that the plurality of first switching elements 210 are SiC-FET devices and the plurality of second switching elements 310 are Si-IGBT devices.

[0033] The motor M may be driven by receiving AC power converted by the first inverter 200 and the second inverter 300. That is, the motor M is driven by power provided by the first inverter 200 and the second inverter 300 to drive the vehicle.

[0034] like Figure 2As shown in , the current sensor 500 is disposed between the first inverter 200, the second inverter 300 and the motor M and can detect the current input to the motor M. Specifically, the current sensor 500 can be arranged between the multiple output terminals of the multiple first switching elements 210 connected in parallel and the respective phases a, b, and c of the motor M, and can be arranged between the multiple output terminals of the multiple second switching elements 310 connected in parallel and the respective phases a, b, and c of the motor M. That is, the current sensor 500 can detect the current of the respective phases a, b, and c of the input motor M at each of the multiple output terminals of the multiple first switching elements 210 connected in parallel and the multiple second switching elements 310 connected in parallel.

[0035] The controller 400 may generate a PWM signal for controlling the driving of the motor M. Here, the controller 400 may receive an output current of the motor M, and compare the output current of the motor M with a current reference, and generate a PWM signal to guide the output current of the motor M to converge to the current reference.

[0036] In addition, the controller 400 can determine the fault occurrence position between the first inverter 200 and the second inverter 300 and the motor M based on the current detected at the current sensor 500. In this case, when the current is not detected at a specific position by the current sensor 500, the controller 400 can determine the fault (such as a broken line) that occurred at the corresponding position. In addition, if the fault occurrence position is determined, the controller 400 can drive the motor M through the first inverter 200 or the second inverter 300 according to the fault occurrence position.

[0037] For example, for reference Figure 3 To describe, when no current is detected between the first inverter 200 and the motor M, the controller 400 may determine that a fault occurs between the first inverter 200 and the motor M, thereby preventing the operation of the first inverter 200 and allowing the motor M to be driven by the second inverter 300 connected in parallel with the first inverter 200. On the other hand, when no current is detected between the second inverter 300 and the motor M, the controller 400 may determine that a fault occurs between the second inverter 300 and the motor M, thereby preventing the operation of the second inverter 300 and allowing the motor M to be driven by the first inverter 200 connected in parallel with the second inverter 300.

[0038] As described above, in the present disclosure, when a fault (such as wire breakage, etc.) occurs between the inverter and the motor, according to the above method, the vehicle continues to travel in the limp home mode so that the vehicle can be stored in a service center for repair.

[0039] On the other hand, when it is determined that no fault occurs between the first inverter 200, the second inverter 300 and the motor M, the controller 400 may control the driving (manipulation) of the first inverter 200 and the second inverter 300 based on the required output of the motor M. Here, the required output of the motor M may be the required output of the vehicle. In other words, the controller 400 may drive one or more of the first inverter 200 and the second inverter 300 according to a fuel economy driving mode in which the required output of the vehicle is relatively low and a sport mode or a high output mode in which the required output of the vehicle is relatively high, thereby driving the motor M.

[0040] More specifically, when the required output of the motor M is less than a reference, that is, in a fuel economy driving mode in which the required output of the vehicle is relatively low, the controller 400 may drive the first inverter 200 by inputting a PWM signal to the plurality of first switching elements 210. In other words, when the required output of the motor M is less than a predetermined reference, the controller 400 converts the electric energy provided from the energy storage device 100 into AC power through the first inverter 200 and transmits the AC power to the motor M, thereby improving the overall fuel efficiency of the vehicle.

[0041] In addition, when the required output of the motor M is greater than the reference, that is, in the sport mode or high output mode where the required output of the vehicle is relatively high, the controller 400 may drive the second inverter 300 by inputting a PWM signal to the plurality of second switching elements 310. In other words, when the required output of the motor M is greater than the predetermined reference, the controller 400 converts the electric energy provided from the energy storage device 100 into AC power through the second inverter 300 and transmits the AC power to the motor M, thereby outputting a high output.

[0042] refer to Figure 3 , when the required output of the motor M is greater than the reference, the controller 400 may control the plurality of first switching elements 210 to be turned on before the plurality of second switching elements 310 and to be turned off after the plurality of second switching elements 310 by inputting a first PWM signal obtained by converting the PWM signal to the first inverter 200. In addition, when the required output of the motor M is greater than the predetermined reference, the controller 400 may control the plurality of second switching elements 310 to be turned on after the plurality of first switching elements 210 and to be turned off before the plurality of first switching elements 210 by inputting a second PWM signal obtained by converting the PWM signal to the second inverter 300.

[0043] As described above, in the present disclosure, when the required output of the motor M is greater than the reference, the PWM signal is converted and input to the first inverter 200 and the second inverter 300 so as to control the multiple first switching elements 210 to be turned on before the multiple second switching elements 310 and to be turned off after the multiple second switching elements 310, so that the switching losses of the multiple first switching elements 210 of the first inverter 200 and the second switching elements 310 of the second inverter 300 can be reduced.

[0044] Reference Figure 2 , the motor M according to one embodiment of the present disclosure may be a single motor that operates by selectively or simultaneously receiving the power converted by the first inverter 200 and the second inverter 300 according to the required output amount of the motor M. Specifically, as Figure 2 As shown in , according to the present embodiment, when the motor M is a three-phase motor, the output terminals of the first inverter 200 and the second inverter 300 are commonly connected to the phases a, b, and c of the motor M. In this case, when the required output of the motor M is less than a predetermined reference, the controller 400 can drive the motor M by controlling the plurality of first switching elements 210 to drive the first inverter 200. In addition, when the required output of the motor M is greater than a predetermined reference, the controller 400 can drive the motor M by controlling the plurality of second switching elements 310 to drive the second inverter 300 or by controlling the plurality of first switching elements 210 and the plurality of second switching elements 310 to drive the first inverter 200 and the second inverter 300.

[0045] refer to Figure 5 , a motor according to another embodiment of the present disclosure may include: a first motor 600 driven by receiving power converted by a first inverter 200 and a second motor 700 driven by receiving power converted by a second inverter 300. More specifically, as Figure 5 As shown in , when the motor is configured with the first motor 600 and the second motor 700, the output terminal of the first inverter 200 can be connected to the phases a, b, and c of the first motor 600, and the output terminal of the second inverter 300 can be connected to the phases a, b, and c of the second motor 700. In this case, when the required output of the motor is less than a predetermined reference, the controller 400 can drive the first motor 600 by controlling the plurality of first switching elements 210 to drive the first inverter 200. In addition, when the required output of the motor is greater than the predetermined reference, the controller 400 can drive the second motor 700 by controlling the plurality of second switching elements 310 to drive the second inverter 300.

[0046] According to the present disclosure, differently controlling the time points at which the first inverter and the second inverter are turned on and off based on the output amount of the motor makes it possible to improve the efficiency and output of the vehicle and reduce the switching loss.

[0047] Furthermore, when a failure such as disconnection occurs between the electric motor and the first inverter and the second inverter, limp-home driving is performed so that the running of the vehicle can be maintained.

[0048] Although specific embodiments of the present disclosure have been described and shown, it will be understood by those skilled in the art that various modifications and substitutions may be made without departing from the technical spirit disclosed in the appended claims.

Claims

1. An inverter system for a vehicle, comprising: an energy storage device configured to store electrical energy; a first inverter comprising a plurality of first switching elements, wherein the first inverter is configured to convert the electric energy stored in the energy storage device into AC power; a second inverter comprising a plurality of second switching elements different from the plurality of first switching elements, wherein the second inverter is connected to the energy storage device in a parallel relationship with the first inverter and is configured to convert the electrical energy stored in the energy storage device into AC power; a motor configured to be driven by receiving the AC power converted by the first inverter and the second inverter; current sensors disposed between the first inverter and the motor and between the second inverter and the motor, respectively, wherein each of the current sensors is configured to detect a current input into the motor; and a controller configured to: generate a pulse width modulation signal for controlling the driving of the motor, determine a fault occurrence position between the first inverter and the motor or between the second inverter and the motor based on the detected current, and control the motor to be driven by the first inverter or the second inverter according to the fault occurrence position, Wherein, when there is no fault between the first inverter and the motor and between the second inverter and the motor, the controller controls the operation of the first inverter and the second inverter based on the required output of the motor, wherein, when the required output of the motor is less than a reference value, the controller controls the plurality of first switching elements to operate the first inverter, wherein the switching loss and conduction loss of the first inverter are smaller than the switching loss and conduction loss of the second inverter, When the required output of the motor is greater than a reference value, the controller controls the plurality of second switching elements to operate the second inverter. The first inverter has a rated output for driving the motor that is smaller than a rated output of the second inverter for driving the motor.

2. The inverter system according to claim 1, wherein: When a fault occurs between the first inverter and the motor, the controller controls the motor to be driven by the second inverter, and When a fault occurs between the second inverter and the motor, the controller controls the motor to be driven by the first inverter.

3. The inverter system according to claim 1, wherein: When the required output of the motor is greater than a reference value, the controller inputs a first pulse width modulation signal obtained by converting the pulse width modulation signal to the first inverter to control the multiple first switching elements to be turned on before the multiple second switching elements and to be turned off after the multiple second switching elements.

4. The inverter system according to claim 1, wherein: When the required output of the motor is greater than a reference value, the controller inputs a second pulse width modulation signal obtained by converting the pulse width modulation signal to the second inverter to control the multiple second switching elements to be turned on after the multiple first switching elements and to be turned off before the multiple first switching elements.

5. The inverter system according to claim 1, wherein: Each of the plurality of first switching elements is a silicon carbide field effect transistor, and each of the plurality of second switching elements is a silicon insulated gate type bipolar transistor.

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

7. The inverter system according to claim 1, wherein: The electric motor comprises: a first electric motor driven by receiving electric power converted by the first inverter; and The second electric motor is driven by receiving the electric power converted by the second inverter.

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