ELECTRIC DRIVE SYSTEM FOR ELECTRIC VEHICLE

Abstract

Vehicle (112), comprising: an inverter (126); a motor (114, 118) coupled to the inverter (126); a traction battery (124) which is coupled to the inverter (126) and has a terminal voltage equal to a rail voltage between rails (180) of the inverter (126), so that the rail voltage is unregulated; a voltage converter (132) configured to reduce the terminal voltage below an intermediate bus voltage threshold on an intermediate bus (182); and an additional converter configured to take power from the intermediate bus (182) to supply additional consumers.

Description

TECHNICAL AREA

[0001] The present disclosure relates to electric drive systems for vehicles. GENERAL STATE OF THE ART

[0002] Electric vehicles include an electric machine for generating electricity and propulsion. The electric machine may have an inverter to convert direct current (DC) into alternating current (AC), which the electric machine requires. A high-voltage or traction battery can supply electricity to the electric propulsion machine or electric propulsion motor. The inverter may include a boost converter to increase the voltage of the rails connected to the inverter in order to maintain the inverter voltage supplied by the battery.

[0003] Document DE 10 2011 009 706 A1 discloses an electric powertrain for a vehicle and a method for operating a vehicle with an electric powertrain comprising a high-voltage network (high-voltage bus), a traction inverter, and an electric machine, wherein the traction inverter is coupled between the high-voltage bus and the electric machine. The method includes generating an electrical voltage for the high-voltage bus with the electric machine and the traction inverter when the electric machine is mechanically driven.

[0004] Document DE 10 2012 000 442 A1 describes vehicle systems that include electric and hybrid powertrain systems, in particular comprising a high-voltage battery that is electrically connected via a high-voltage bus to a rectifier / inverter and a DC / DC converter, wherein the DC / DC converter is electrically connected to a low-voltage bus and a low-voltage battery. SUMMARY

[0005] A vehicle may include an inverter, a motor coupled to the inverter, and a traction battery coupled to the inverter with a terminal voltage equal to the rail voltage between the inverter's rails, meaning the rail voltage is unregulated. The vehicle may also include a voltage converter configured to reduce the terminal voltage below an intermediate bus voltage threshold, and an auxiliary converter configured to draw power from the intermediate bus to supply additional loads.

[0006] An electrical distribution system of the vehicle may include a half-bridge step-down converter configured to take power from a traction battery, which may be electrically coupled to an inverter bus and may have a terminal voltage equal to an inverter bus voltage, and to step down the terminal voltage to an intermediate bus voltage, which supplies power to an auxiliary voltage regulator that may be configured to maintain an auxiliary bus voltage of an auxiliary bus.

[0007] A procedure can be carried out by a vehicle's control system and may include the following steps: actuating switches of a voltage converter to reduce a terminal voltage of a traction battery to supply an intermediate bus, actuating switches of an inverter that takes an unregulated voltage from a traction battery equal to the battery's terminal voltage to drive an electric machine, and actuating switches of an auxiliary converter to reduce an intermediate bus voltage to supply auxiliary consumers. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is an overview of a hybrid electric vehicle with a power-split configuration; and Fig. Figure 2 is a schematic view of an electric drive for the hybrid electric vehicle with a step-down converter. DETAILED DESCRIPTION

[0008] Embodiments of the present disclosure are described herein. It is understood, however, that the disclosed embodiments are merely examples and that other embodiments may take different and alternative forms. The figures are not necessarily to scale; some features may be greatly enlarged or reduced to show details of certain components. Accordingly, the specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis to teach a person skilled in the art the diverse uses of the present invention.As the person skilled in the art will understand, various features illustrated and described with reference to any of the figures can be combined with features illustrated in one or more other figures to create embodiments not expressly illustrated or described. The combinations of illustrated features provide representative embodiments for typical applications. However, various combinations and modifications of the features, consistent with the teachings of this disclosure, may be desirable for specific applications or implementations.

[0009] Hybrid and electric vehicles have electric drive systems to supply and receive power from electric machines. These electric machines can be drive motors, generators, or a combination of both. The electric drive system may include a high-voltage or traction battery. The traction battery may be configured to directly supply the voltage required by the inverter. This means the inverter's rails are connected to the battery without a boost converter. The higher voltage of the battery makes it impossible for typical auxiliary power converters (e.g., electric air conditioning, auxiliary power bus) to step down the voltage, as required by current standard configurations.To maintain voltage at the required auxiliary consumers, a variable voltage step-down converter can be configured to reduce the bus voltage supplied by the traction battery, allowing the auxiliary voltage converters to further reduce the voltage without adjustment. This enables power savings from the electric vehicle by increasing the terminal voltage of the traction battery and providing a step-down converter without additional modification.

[0010] Fig. Figure 1 shows an electrified vehicle 112, which can be referred to as a plug-in hybrid electric vehicle (PHEV). A plug-in hybrid electric vehicle 112 can include one or more electric machines 114 mechanically coupled to a hybrid transmission 116. The electric machines 114 can operate as a motor or generator. Additionally, the hybrid transmission 116 is mechanically coupled to a motor 118. The hybrid transmission 116 is also mechanically coupled to a drive shaft 120, which is mechanically coupled to the wheels 122. The electric machines 114 can provide propulsion or deceleration when the motor 118 is switched on or off. The electric machines 114 can also act as generators, providing fuel efficiency benefits by recovering energy that would normally be lost as heat in a friction braking system.The electric motors 114 can also reduce the vehicle's emissions by allowing the motor 118 to operate at more efficient speeds and by enabling the hybrid electric vehicle 112 to operate in an electric mode in which the motor 118 is switched off under certain conditions. An electrified vehicle 112 can also be a battery electric vehicle (BEV). In a BEV configuration, the motor 118 may not be present. In other configurations, the electrified vehicle 112 can be a full hybrid electric vehicle (FHEV) without plug-in capability.

[0011] A traction battery or battery pack 124 stores energy that can be used by the electric machines 114. The vehicle battery pack 124 can provide a high-voltage direct current (DC) output. The traction battery 124 can be electrically coupled to one or more power electronics modules 126. One or more contactors 142 can, when open, isolate the traction battery 124 from other components and, when closed, connect the traction battery 124 to other components. The power electronics module 126 is also electrically coupled to the electric machines 114 and provides the capability for bidirectional energy transfer between the traction battery 124 and the electric machines 114. For example, a traction battery 124 can provide a DC voltage while the electric machines 114 operate on three-phase alternating current (AC).The power electronics module 126 can convert the DC voltage into three-phase AC current to operate the electric machines 114. In a regeneration mode, the power electronics module 126 can convert the three-phase AC current from the electric machines 114, which act as generators, into DC voltage that is compatible with the traction battery 124.

[0012] In addition to providing energy for propulsion, the traction battery 124 can supply energy to other electrical systems of the vehicle. The vehicle 112 can include a DC / DC converter module 128, which converts the high-voltage DC output of the traction battery 124 into a low-voltage DC supply compatible with low-voltage vehicle consumers. An output of the DC / DC converter module 128 can be electrically connected to an auxiliary battery 130 (e.g., a 12 V battery) to charge the auxiliary battery 130. The low-voltage systems can also be electrically connected to the auxiliary battery 130. A step-down converter 132 can be located on the high-voltage bus to reduce bus voltages for the electrical consumers 146 and the DC / DC converter 128. One or more electrical consumers 146 can be connected to the high-voltage bus.The electrical loads 146 may have an associated control unit that operates and controls the electrical loads 146 appropriately. Examples of electrical loads 146 may be a fan, an electric heating element, and / or an air conditioning compressor.

[0013] One or more wheel brakes 144 can be provided to slow down the vehicle 112 and prevent it from moving. The wheel brakes 144 can be actuated hydraulically, electrically, or in a combination thereof. The wheel brakes 144 can form part of a braking system 150. The braking system 150 can include other components to operate the wheel brakes 144. For simplicity, the figure shows a single connection between the braking system 150 and one of the wheel brakes 144. A connection between the braking system 150 and the other wheel brakes 144 is implied. The braking system 150 can include a controller to monitor and coordinate the braking system 150. The braking system 150 can monitor the brake components and control the wheel brakes 144 to slow down the vehicle.The Brake System 150 can respond to commands from the driver and can also operate autonomously to implement features such as stability control. The Brake System 150's control unit can implement a procedure for applying the required braking force when requested by another control unit or sub-function.

[0014] Electronic modules in the vehicle 112 can communicate via one or more vehicle networks. The vehicle network can include a variety of communication channels. One channel of the vehicle network can be a serial bus, such as a CAN (Controller Area Network) bus. One of the vehicle network channels can be an Ethernet network, defined by the IEEE 802 series of standards. Additional vehicle network channels can include discrete connections between modules and can carry power signals from the auxiliary battery 130. Different signals can be transmitted over different channels of the vehicle network. For example, video signals can be transmitted over a high-speed channel (e.g., Ethernet), while control signals can be transmitted over CAN or discrete signals.The vehicle network can include all hardware and software components that contribute to the transmission of signals and data between modules. The vehicle network is in . Fig. Figure 1 is not shown, but it can be implied that the vehicle network can be connected to any electronic module present in the vehicle 112. A vehicle system controller (VSC) 148 may be present to coordinate the operation of the various components.

[0015] Now, with reference to Fig. Figure 2 shows an electrical distribution system for the vehicle 112. The distribution system includes a high-voltage traction battery 124, which is connected to the busbars 180 of the inverter 126. The busbars 180 have the same voltage as the terminals of the traction battery 124. The terminal voltage can be higher than 500 volts. The inverter 126 is connected to a traction motor 114 or a generator. A voltage converter 132 is connected in parallel to the inverter 126 and the high-voltage battery 124. The voltage converter 132 has an output to an intermediate bus 182, which supplies power to other auxiliary loads, including a DC / DC converter 128 and an electric AC compressor DC / DC converter 146. The voltage converter 132 can be a step-down converter, as shown in Figure 2. Fig.2 shown, or another type of voltage regulator known or currently unknown in the field. The intermediate bus 182 can have a voltage below 400 volts. Both converters 128 and 146 are auxiliary regulators for additional electrical consumers. The auxiliary regulators 128 and 146 can also be step-down converters or another type of voltage regulator known or currently unknown in the field. The auxiliary regulators can be configured to maintain an auxiliary bus voltage to supply the electrical consumers. The auxiliary electrical consumers can be a vehicle air conditioning system, a heating system, infotainment systems, vehicle control systems, or other vehicle or non-vehicle consumers that require a step-down voltage.The voltage converter 132 can include an upper and lower switch 172, 170 with respective antiparallel diodes and a capacitor pair 178 of an intermediate inductor 174 in a low-pass filter arrangement. The switches can be IGBT switches or any other type of semiconductor switch. The vehicle can also include a smoothing capacitor 176 in parallel with the rails 180 of the inverter 126 to maintain the rail voltage.

Claims

[1] Vehicle (112), comprising: an inverter (126); a motor (114, 118) coupled to the inverter (126); a traction battery (124) which is coupled to the inverter (126) and has a terminal voltage equal to a rail voltage between rails (180) of the inverter (126), so that the rail voltage is unregulated; a voltage converter (132) configured to reduce the terminal voltage below an intermediate bus voltage threshold on an intermediate bus (182); and an additional converter configured to take power from the intermediate bus (182) to supply additional consumers. [2] Vehicle (112) according to claim 1, wherein the voltage converter (132) includes an upper and lower switch (172, 170) with respective antiparallel diodes and a capacitor pair (178) of an intermediate inductor (174) in a low-pass filter output arrangement, such that the output voltage is regulated by switching the switches (172, 170). [3] Vehicle (112) according to claim 1, wherein the voltage converter (132) is a step-down converter. [4] Vehicle (112) according to claim 1, wherein the additional converter is a step-down converter. [5] Vehicle (112) according to claim 1, wherein the intermediate bus voltage threshold is 400 volts. [6] Vehicle (112) according to claim 1, wherein the terminal voltage is above 400 volts. [7] Electrical distribution system of a vehicle (112), comprising: a half-bridge buck converter configured to to receive power from a traction battery (124) which is electrically coupled to an inverter bus (180) and has a terminal voltage equal to a voltage of the inverter bus (180), and to transform the terminal voltage down to an intermediate bus voltage, which supplies power to an auxiliary voltage regulator configured to maintain an auxiliary bus voltage of an auxiliary bus. [8] Electrical distribution system of a vehicle (112) according to claim 7, wherein the terminal voltage is higher than 400 volts. [9] Electrical distribution system of a vehicle (112) according to claim 7, wherein the intermediate bus voltage is below 400 volts. [10] Electrical distribution system of a vehicle (112) according to claim 7, wherein the auxiliary bus is connected to an air conditioning system of the vehicle (112). [11] Electrical distribution system of a vehicle (112) according to claim 7, wherein the auxiliary bus is connected to an auxiliary battery (130). [12] Procedures, including: by controlling a vehicle (112), Operating a voltage converter (132) and an inverter (126) connected to an unregulated terminal voltage of a traction battery (124), such that the voltage converter (132) reduces the voltage to supply an intermediate bus voltage, and the inverter (126) drives an electric machine (114); and Operating an additional converter to reduce the intermediate bus voltage in order to supply additional consumers. [13] Method according to claim 12, wherein the voltage converter (132) includes an upper and lower switch (172, 170) with respective antiparallel diodes and a capacitor pair (178) of an intermediate inductor (174) in a low-pass filter output arrangement, such that the output voltage is regulated by switching the switches (172, 170). [14] Method according to claim 12, wherein the voltage converter (132) is a step-down converter. [15] Method according to claim 12, wherein the additional converter is a step-down converter.

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