All-in-one DC vehicle charger

Abstract

The present disclosure provides an "integrated DC vehicle charger." A vehicle has a drive system including a battery, two inverters, a motor, and a switch. The vehicle also has a controller that operates the switch to couple one of the inverters to a charging port and operates at least one of the inverters to cause DC current from the charging port to flow through the one of the inverters, the motor, and the other of the inverters to the battery in sequence in response to a charging mode.

Description

Technical Field

[0001] The present disclosure relates to automotive electric drive and charging systems. Background Art

[0002] Hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs) can rely on traction batteries to power traction motors for propulsion, with a power inverter in between converting direct current (DC) power to alternating current (AC) power. Typical AC traction motors are three-phase motors powered by three sinusoidal signals, each driven with 120 degrees of phase separation, but other configurations are possible. Furthermore, many electrified vehicles may include a DC-DC converter to convert the voltage of the traction battery to the operating voltage level of the traction motor. Summary of the Invention

[0003] A vehicle has a traction battery; an electric motor having two sets of windings sharing a common neutral line; and a first inverter and a second inverter. During propulsion, each inverter powers a dedicated set of the windings using power from the traction battery, and during charging, directs charging current from a charging port sequentially through the first inverter, the windings, and the second inverter to the traction battery.

[0004] A vehicle has a drive system including a battery, two inverters, a motor, and a switch. The vehicle also has a controller that, in response to a charging mode, operates the switch to connect one of the inverters to a charging port, and operates at least one of the inverters so that a direct current from the charging port flows sequentially through the one of the inverters, the motor, and the other of the inverters to the battery.

[0005] A method for controlling a vehicle powertrain system includes: coupling, by a controller, one of a pair of inverters to a charging port in response to a charging mode so that a direct current from the charging port flows sequentially through the one of the pair of inverters, a motor, and the other of the pair of inverters to a traction battery; and decoupling the one of the pair of inverters from the charging port and coupling the one of the pair of inverters to the traction battery in response to a propulsion mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 Schematic diagram of a conventional off-board DC vehicle fast charging ecosystem.

[0007] Figure 2 is a schematic diagram of the powertrain system of an electrified vehicle.

[0008] Figure 3 Schematic diagram of an electrified vehicle powertrain with integrated DC charging capability.

[0009] Figure 4 is a schematic diagram of an electrified vehicle. DETAILED DESCRIPTION

[0010] Various embodiments of the present disclosure are described herein. However, the disclosed embodiments are merely exemplary, and other embodiments may take various forms and alternative forms not expressly shown or described. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural details and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the invention in different ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the accompanying drawings may be combined with features shown in one or more other drawings to produce embodiments not expressly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of the present disclosure may be desired for particular applications or implementations.

[0011] Despite their architectural differences, electric vehicles (EVs) share similarities in their structure. For example, batteries, inverters, and electric motors are typical building blocks of EVs. To energize the batteries and power the motors, two types of chargers can be used: onboard chargers and off-board (standalone) chargers. Onboard chargers offer the flexibility of charging anywhere there is an electrical outlet. However, they can add weight, bulk, and cost to the vehicle. Therefore, it is desirable to avoid these drawbacks by using existing hardware, such as inverters and electric motors, to charge the batteries.

[0012] Considering that the vehicle is not driven during charging and that the battery is not charged during driving except by means of regenerative braking, it seems feasible to integrate the on-board charger and the traction system. In addition, DC fast chargers are already widespread and many people are focusing on this design. The significant reduction in charging time is what makes these types of chargers attractive. Here, we propose to use the vehicle's multi-phase electric machine to implement a DC charger. In some instances, the combination of two symmetrical inverters and the motor windings forms a full-bridge DC-DC converter. The activation of some of the switches in one of the inverters and the utilization of the diodes of the other inverter can result in a reduction of the DC supply voltage at the battery (buck mode). In this case, the motor windings act as a filter inductor. The activation of the switches of both inverters and the utilization of the diodes of the other inverter can result in an increase of the DC supply voltage at the battery (boost mode). In this case, the motor windings act as a boost inductor. In both cases, if the switches are not operated simultaneously, interleaved operation can be performed, which can improve the output voltage quality.

[0013] Referring to Figure 1 , a conventional off-board DC fast charging ecosystem 10 for a vehicle 12 includes a medium voltage utility grid 14, a conventional transformer 16, a building electrical line 18, an off-board DC fast charger 20, and a charging cord 22. The off-board DC fast charger 20 includes an AC / DC converter 24, a capacitor 26, and a DC / DC converter 28. AC power from the medium voltage utility grid is transmitted to the building electrical line 18 via the conventional transformer 16. The AC power is then converted to DC power by the off-board DC fast charger 20 in the usual manner for delivery to the vehicle 12 via the charging cord 22.

[0014] Referring to Figure 2 , a traction drive system 30 includes a traction battery 32, symmetrical inverters 34, 36, and an electric machine 38. Each of the inverters 34, 36 includes switching elements and a DC link capacitor as is conventional. In other arrangements, only one of the inverters 34, 36 can include a DC link capacitor as is known in the art. The electric machine 38 includes two sets of windings 40, 42, three windings in each set, and a common neutral 44. That is, the electric machine 38 is a six-phase electric machine. During propulsion, DC power from the traction battery 32 is converted by the inverters 34, 36 to AC power for delivery to the electric machine 38. During regenerative braking, AC power from the electric machine 38 is converted by the inverters 34, 36 to DC power for delivery to the traction battery 32.

[0015] Referring to Figure 3Traction drive system 46 with integrated fast charging capability includes a traction battery 48, inverters 50, 52, and a motor 53. In this example, inverter 50 includes switch-diode pairs 54, 56, 58, 60, 62, 64, and a DC link capacitor 66. Furthermore, inverter 52 includes switch-diode pairs 68, 70, 72, 74, 76, 78, and a DC link capacitor 80. Motor 53 includes windings 82, 84, 86, 88, 90, 92, and a common neutral line 94. Windings 82, 84, 86 and 88, 90, 92 are arranged in two groups of three. That is, motor 53 is a six-phase motor.

[0016] In other arrangements, only one of the inverters (e.g., inverter 52) may include a DC link capacitor. In such an arrangement, the DC link function may need to be associated with the charging port 99. Furthermore, the motor 53 may include additional sets of windings, which may require the use of additional inverters, etc. Other arrangements are also contemplated.

[0017] The traction drive system 46 also includes a switchgear 96 and a controller 98. The switchgear 96 includes switches S1 and S2 that selectively electrically couple a charging port 99 thereto. The charging port 99 is configured to receive power from a DC power source 100. The inverters 50 and 52, the motor 53, and the switchgear 96 are in communication with and / or controlled by the controller 98.

[0018] During propulsion, the controller 98 places the switch S1 in position X and opens the switch S2 to electrically connect the traction battery 48 to the inverter 50 and disconnect the charging port 99 from the traction drive system 46. The DC power from the traction battery 48 can then be converted to AC power via the inverters 50, 52 for delivery to the motor 53.

[0019] During charging, the controller 98 places the switch S1 in position Y and closes the switch S2 to electrically connect the inverter 50 to the charging port 99 and disconnect the traction battery 48 from the inverter 50. The DC power from the charging port 99 can then flow through the inverter 50, the motor 53, the inverter 52, and to the traction battery 48.

[0020] If the power from the charging port 99 is neither stepped up nor stepped down, the controller 98 may close one or more of the switches of the switch-diode pairs 54 , 58 , 62 to allow current to flow through the corresponding windings and neutral of the motor 53 and the diodes of the corresponding switch-diode pairs 68 , 72 , 76 to the traction battery 48 .

[0021] If the power from the charging port 99 is to be reduced in voltage, the controller 98 can enable one or more of the switches of the switch-diode pairs 54, 58, 62 at a certain duty cycle to cause current to flow intermittently through the corresponding windings and neutral of the motor 53 and the diodes of the corresponding switch-diode pairs 68, 72, 76 to the traction battery 48.

[0022] If the power from the charging port 99 is to be boosted, the controller 98 may enable one or more of the switches of the switch-diode pairs 54 , 58 , 62 and one or more of the switches of the switch-diode pairs 70 , 74 , 78 at a duty cycle so that current intermittently flows through the corresponding windings and neutral of the motor 53 and intermittently flows through the diodes of the corresponding switch-diode pairs 68 , 72 , 76 and the switches of the corresponding switch-diode pairs 70 , 74 , 78 to the traction battery 48 .

[0023] In this design, switches S1 and S2 are used to disconnect the traction battery 48 from the inverter 50. Thus, the inverters 50 and 52 and windings 82-92 form a three-way interleaved full-bridge DC-DC converter. This adds a DC-DC stage, rather than connecting the traction battery 48 directly to the charging port 99 as in conventional DC fast-charging methods. Because this is a full-bridge DC-DC converter, it can both step up and step down the input voltage as described above. This makes the traction drive system 46 compatible with any commercially available DC fast charger, regardless of its output voltage level.

[0024] Some arrangements can provide certain benefits. For example, because the DC-DC stage is incorporated into the charger, the design of the power supply can be simplified. The system is compatible with different DC voltage levels (different brands and products) because, in the case of a full-bridge DC-DC converter, the voltage can be adjusted to any desired value. Compared to conventional DC fast charging, there are no added components, except for two possible switches. Due to the full control of the output voltage level, trickle charging is possible. This can be useful if the battery voltage is low for any reason and charging at conventional power may cause problems. The three-way interleaved design can reduce the current ripple on the DC bus and thereby extend the service life of the components. Due to the boost function, the input voltage of the charger can be reduced.

[0025] The architecture envisioned in this paper can be implemented in a variety of vehicle configurations. For example, Figure 4An electrified vehicle 102 is shown that includes one or more electric machines 104 mechanically coupled to a hybrid transmission 106. The electric machines 104 can operate as motors or generators. Additionally, the hybrid transmission 106 is mechanically coupled to an engine 108 and a drive shaft 110 that is mechanically coupled to wheels 112.

[0026] The traction battery or battery pack 114 stores energy that can be used by the motor 104. The vehicle battery pack 114 can provide a high-voltage direct current (DC) output. The traction battery 114 can be electrically coupled to one or more power electronics modules 116 that implement the architecture discussed above. One or more contactors 118 can further isolate the traction battery 114 from other components when open, and connect the traction battery 114 to the other components when closed. The power electronics module 116 is also electrically coupled to the motor 104 and provides the ability to transfer energy bidirectionally between the traction battery 114 and the motor 104. For example, the traction battery 114 can provide a DC voltage, while the motor 104 operates on alternating current (AC) to function. The power electronics module 116 can convert the DC voltage into AC to operate the motor 104. In regenerative mode, the power electronics module 116 can convert the AC power from the motor 104, which acts as a generator, into a DC voltage compatible with the traction battery 114.

[0027] The vehicle 102 may include a variable voltage converter (VVC) (not shown) electrically coupled between the traction battery 114 and the power electronics module 116. The VVC may be a DC / DC boost converter configured to increase or boost the voltage provided by the traction battery 114. By increasing the voltage, current requirements may be reduced, resulting in a reduction in wiring size for the power electronics module 116 and the electric motor 104. Additionally, the electric motor 104 may operate with higher efficiency and lower losses.

[0028] In addition to providing energy for propulsion, the traction battery 114 can also provide energy for other vehicle electrical systems. The vehicle 102 can include a DC / DC converter module 120 that converts the high-voltage DC output of the traction battery 114 into a low-voltage DC power source compatible with low-voltage vehicle loads 121. The output of the DC / DC converter module 120 can be electrically coupled to an auxiliary battery 122 (e.g., a 12V battery) to charge the auxiliary battery 122. Low-voltage systems can be electrically coupled to the auxiliary battery 122. One or more electrical loads 124 can be coupled to the high-voltage bus. The electrical loads 124 can have associated controllers that operate and control the electrical loads 124 as needed. Examples of electrical loads 124 can include fans, electric heating elements, and / or air conditioning compressors.

[0029] The electrified vehicle 102 can be configured to recharge the traction battery 114 from an external power source 126. The external power source 126 can be a connection to an electrical outlet. The external power source 126 can be electrically coupled to a charger or electric vehicle supply equipment (EVSE) 128. The external power source 126 can be a distribution network or transmission grid provided by a utility company. The EVSE 128 can provide circuitry and controls to regulate and manage the transfer of energy between the power source 126 and the vehicle 102. The external power source 126 can provide DC or AC power to the EVSE 128. The EVSE 128 can have a charging connector 130 for plugging into a charging port 132 of the vehicle 102. The charging port 132 can be any type of port configured to transfer power from the EVSE 128 to the vehicle 102. The EVSE connector 130 can have pins that mate with corresponding recesses in the charging port 132. Alternatively, the various components described as being electrically coupled or connected can use wireless inductive coupling to transfer power.

[0030] In some configurations, the electrified vehicle 102 can be configured to provide power to an external load. For example, the electrified vehicle can be configured to operate as a backup generator or power outlet. In such an application, the load can be connected to the EVSE connector 130 or other outlet. The electrified vehicle 102 can be configured to return power to the power source 126. For example, the electrified vehicle 102 can be configured to provide alternating current (AC) power to the power grid. The voltage supplied by the electrified vehicle can be synchronized with the power line.

[0031] The electronic modules in the vehicle 102 can communicate via one or more vehicle networks. The vehicle network can include multiple channels for communication. One channel of the vehicle network can be a serial bus, such as a controller area network (CAN). One of the channels of the vehicle network can include an Ethernet network defined by the Institute of Electrical and Electronics Engineers (IEEE) 802 series of standards. Additional channels of the vehicle network can include discrete connections between modules and can include power signals from the auxiliary battery 122. Different signals can be transmitted on different channels of the vehicle network. For example, a video signal can be transmitted via a high-speed channel (e.g., Ethernet), while control signals can be transmitted via CAN or discrete signals. The vehicle network can include any hardware and software components that facilitate the transmission of signals and data between modules. The vehicle network is not shown, but it can be implied that the vehicle network can be connected to any electronic module present in the vehicle 102. A vehicle system controller (VSC) 134 can be present to coordinate the operation of the various components.

[0032] The vehicle 102 also includes a DC / DC converter module 120 for converting the voltage of the high voltage bus to a voltage level suitable for the auxiliary battery 122 and low voltage loads 121 (e.g., approximately 12 volts). The vehicle 102 can also include additional switches, contactors, and circuitry to selectively select the flow of power between the traction battery 114 and the DC / DC converter 120.

[0033] The disclosed processes, methods, logic, or strategies can be provided to and / or implemented by a processing device, controller, or computer, which can include any existing programmable electronic control unit or special purpose electronic control unit. Similarly, the processes, methods, logic, or strategies can be stored as data and instructions executable by a controller or computer in a number of forms, including but not limited to: information permanently stored on various types of articles, which can include persistent, non-writable storage media such as ROM devices; and information variably stored on writable storage media, such as floppy disks, tapes, CDs, RAM devices, and other magnetic and optical media. The processes, methods, logic, or strategies can also be implemented in software executable objects. Alternatively, they can be embodied in whole or in part by suitable hardware components, such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices, or a combination of hardware, software, and firmware components.

[0034] The language used in the specification is descriptive, not limiting, and it is understood that changes can be made in the specific details disclosed without departing from the spirit and scope of the disclosure and the claims. As previously described, features of various embodiments can be combined to form further embodiments not explicitly described or illustrated. While various embodiments can have been described as providing advantages or superior features over other embodiments or prior art implementations, it will be appreciated that one or more features or characteristics described in connection with one or more embodiments can be selectively applied to other embodiments without departing from the scope of the disclosure as claimed. Such features or characteristics can include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, and the like. As such, embodiments described as not being as desirable as other embodiments or prior art implementations for one or more features or characteristics can be as desirable and can be the preferred embodiment for the particular application and can be the best mode contemplated.

Claims

1. A vehicle, comprising: traction batteries; a motor having two sets of windings sharing a common neutral line; as well as A first inverter and a second inverter, wherein the first inverter and the second inverter are configured to: During propulsion, each inverter powers a dedicated one of the two sets of windings using power from the traction battery, and During charging, at least one switch of the first inverter is turned on or enabled at a predetermined duty cycle, thereby directing DC current from the charging port through the first inverter, the two sets of windings, and the second inverter to the traction battery.

2. The vehicle of claim 1 , further comprising a switch arrangement configured to selectively couple the first inverter to the traction battery and disconnect the first inverter from the charging port during propulsion.

3. The vehicle of claim 1 , further comprising a switch device configured to selectively couple the first inverter to the charge port and disconnect the first inverter from the traction battery during charging.

4. The vehicle of claim 1 , further comprising a controller programmed to operate the inverter to reduce the voltage at the traction battery during charging.

5. The vehicle of claim 1 further comprising a controller programmed to operate the inverter to increase the voltage at the traction battery during charging.

6. The vehicle of claim 1, wherein the motor is a six-phase motor.

7. A vehicle, comprising: A drive system comprising a battery, two inverters, a motor, and a switch; as well as A controller is programmed to operate the switch to couple one of the inverters to a charging port in response to a charging mode, and to enable at least one switch of the one of the inverters at a predetermined duty cycle so that a direct current from the charging port flows sequentially through the one of the inverters, the motor, and the other of the inverters to the battery.

8. The vehicle of claim 7, wherein the controller is further programmed to operate the inverter to reduce the voltage at the battery.

9. The vehicle of claim 7, wherein the controller is further programmed to operate the inverter to increase the voltage at the battery.

10. The vehicle of claim 7, wherein the controller is further programmed to operate the switch to couple the one of the inverters to the battery and disconnect the one of the inverters from the charging port in response to a propulsion mode so that each of the inverters powers a set of windings of the electric motor.

11. The vehicle of claim 7, wherein the motor includes two sets of windings sharing a common neutral line.

12. A method for controlling a vehicle powertrain system, the method comprising: Through the controller, In response to a charging mode, one of the pair of inverters is coupled to a charging port, and at least one switch of the one of the pair of inverters is turned on or enabled at a predetermined duty cycle so that a direct current from the charging port flows sequentially through the one of the pair of inverters, a motor, and the other of the pair of inverters to a traction battery; and In response to a propulsion mode, the one of the pair of inverters is decoupled from the charging port and the one of the pair of inverters is coupled to the traction battery.

13. The method of claim 12, further comprising operating at least one of the inverters to reduce the voltage at the traction battery.

14. The method of claim 12, further comprising operating at least one of the inverters to increase the voltage at the traction battery.

15. The method of claim 12, further comprising operating at least one of the inverters to maintain a voltage at the traction battery.

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