Patent Grant
11607968
This disclosure relates to vehicle power systems and the control thereof.
Certain vehicles may be powered by electric machines that convert electrical energy to mechanical energy.
A vehicle power system has a DC to AC converter, a pair of AC to DC converters, and a transformer including a core, a primary winding wound about the core and electrically connected to an output of the DC to AC converter, and a pair of secondary windings wound about the core. Each of the secondary windings is electrically connected to an input of one of the AC to DC converters. The system also has a controller that operates in a charge mode such that a magnitude of voltage at an input of the DC to AC converter is half of a magnitude of voltage at a collective output of the AC to DC converters to transfer power from the input of the DC to AC converter to the collective output. Voltages of capacitors of the AC to DC converters are balanced.
A vehicle has a DC to AC converter, a pair of AC to DC converters, and a transformer including a core, a primary winding wound about the core and electrically connected to an output of the DC to AC converter, and a pair of secondary windings wound about the core. Each of the secondary windings is electrically connected to an input of one of the AC to DC converters. The vehicle also has a traction battery electrically connected to a collective output of the AC to DC converters, a motor drive electrically connected to the collective output such that the traction battery is electrically between the collective output and the motor drive, and a controller. The controller operates in a drive mode such that switches of one of the AC to DC converters activate with a duty cycle, and switches of the other of the AC to DC converters and DC to AC converter are off to transfer power from the traction battery to the motor drive or vehicle loads.
A vehicle power system has a DC to AC converter, a pair of AC to DC converters, and a transformer including a core, a primary winding wound about the core and electrically connected to an output of the DC to AC converter, and a pair of secondary windings wound about the core. Each of the secondary windings is electrically connected to an input of one of the AC to DC converters. The system also has a traction battery electrically connected to a collective output of the AC to DC converters, and a controller that operates in a grid power/on-board generator mode such that switches of at least one of the AC to DC converters activate with a duty cycle and switches of the DC to AC converter remain off to transfer power from the traction battery to the input of the DC to AC converter.
Embodiments are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments may take various and alternative forms. The figures are not necessarily to scale. Some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art.
Various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.
Increasing DC bus voltage is a trend to enhance power capability of traction inverters and motors. Recently, 800V DC bus-based electric drive systems are a topic of interest. When a high DC bus voltage is designed, the existing OBC 20, OBG 18, APM 24, and other electronic loads 22 may no longer be applicable because they are rated for a lower voltage (e.g., 400V). They should be re-designed to fit a higher DC bus voltage, which may result in more expense and development time.
In addition, for a 400V system, the converters such as the OBC 20 and APM 24 use switches (e.g., MOSFETs) with a voltage rating that is less than 650V to increase switching frequency, reduce converter size, and optimize performance. If the DC bus voltage is 800V however, 1200V power devices should be selected. It may be challenging to select MOSFETs of voltage rating over 650V because of limited choice, higher expense, and lower performance, such as high voltage drops, high reverse recovery losses, high leakage currents, and low switching speeds.
Here, an integrated high voltage (e.g., 800V) traction battery power system for electric vehicle applications is proposed to overcome the issues above.
The DC to AC converter 32 includes switches 50, 52, 54, 56 (e.g., MOSFETs) arranged in a typical H-bridge configuration and capacitor 58. The transformer 38 includes a primary winding 60, secondary windings 62, 64, and a core 66. The AC to DC converter 34 includes switches 68, 70, 72, 74 (e.g., MOSFETs) arranged in a typical H-bridge configuration and capacitor 76. The AC to DC converter 34 includes switches 78, 80, 82, 84 (e.g., MOSFETs) arranged in a typical H-bridge configuration and capacitor 86.
The capacitor 58 is electrically connected across the input of the DC to AC converter 32. The primary winding 60 is wound around the core 66 and electrically connected to the output of the DC to AC converter 32. The secondary windings 62, 64 are wound around the core 66 and are respectively electrically connected to the inputs of the AC to DC converters 34, 36. The capacitor 76 is electrically connected across the output of AC to DC converter 34. The capacitor 86 is electrically connected across the output of the AC to DC converter 36. The vehicle loads 44 are also electrically connected to the output of the AC to DC converter 36.
In this arrangement, when voltage Vb of the traction battery is 800V, the capacitors 58, 76, 86 have voltages of 400V, so the voltage stresses of the switches 50-56, 68-74, 78-84 and capacitors 58, 76, 86 are 400V. 600V MOSFETs can thus be used for the switches 50-56, 68-74, 78-84. With high switching frequency, the (high frequency) transformer 38 can have relatively small size.
A utility grid 88 and plug 90 are shown being electrically connected with the inverter 46. Other arrangements, however, are also possible.
The circuitry of
Power system 28′ for vehicle 30′ includes a DC to AC converter 32′, AC to DC converters 34′, 36′, transformer 38′, traction battery 40′, motor drives 42′, vehicle loads 44′, and inverter/rectifier 46′. The inverter/rectifier 46′ is electrically connected to an input of the DC to AC converter 32′. The transformer 38′ is electrically connected between the DC to AC converter 32′ and AC to DC converters 34′, 36′. The AC to DC converters 34′, 36′ collectively define an output 48′. The traction battery 40′ is electrically connected to the output 48′. The motor drives 42′ are electrically connected to the traction battery 40′ such that the traction battery 40′ is electrically between the AC to DC converters 34′, 36′ and the motor drives 42′.
The DC to AC converter 32′ includes switches 50′, 52′, 54′, 56′ (e.g., MOSFETs) arranged in a typical H-bridge configuration and capacitor 58′. The transformer 38′ includes a primary winding 60′, secondary windings 62′, 64′, and a core 66′. The AC to DC converter 34′ includes switches 68′, 70′, 72′, 74′ (e.g., MOSFETs) arranged in a typical H-bridge configuration and capacitor 76′. The AC to DC converter 36′ includes diodes 92′, 94′, 96′, 98′ arranged in a typical H-bridge configuration and capacitor 86′.
A utility grid 88′ and plug 90′ are shown being electrically connected with the inverter 46′. Other arrangements, however, are also possible as mentioned above.
Operational Modes
Battery Charging Mode—In this mode, the rectifier 46 transfers power from the grid 88 to the traction battery 40. The motor drives 42 are OFF, but the vehicle electronic loads 44 may consume energy. Referring again to
Vehicle Driving Mode—In this mode, the motor drives 42 work to drive the vehicle 30. The inverter/rectifier 46 does not operate and the switches 50-56 and 78-84 are OFF. The switches 68-74 are controlled with 50% duty cycle as shown in
Vehicle to Grid or On-Board Generating Mode—In this mode, the inverter 46 works as an on-board generator or a vehicle to grid facilitator (i.e., vehicle to grid, the traction battery 40 transfers power to the grid 88). The traction battery 40 provides power to the grid 88 or plug 90. The switches 68-74 and 78-84 are controlled at 50% duty cycle as shown in
The topologies and control strategies herein may offer several benefits. Certain arrangements provide an 800V traction battery power system that integrates the functions of an on-board charger, on-board generator, and vehicle to grid facilitator, supplies power to vehicle loads, and achieves an interface between an 800V traction battery and 400V power systems.
A straight forward control method is proposed to operate the integrated traction battery power system. There is only one closed-loop control for battery charging mode, as shown in
For the 800V/400V arrangements, existing 400V hardware designs for on-board chargers, on-board generators, auxiliary power modules, and other electronic loads can be used. Additionally, 600V MOSFETs can be used to achieve the 800V traction battery power system, which eases the burden in selection of components, improves efficiency, and lowers expense. Use of a single high frequency isolated transformer, as opposed to two, to achieve on-board charging and on-board generating functionalities reduces expense, losses, and required packaging space.
The traction battery charging current is 100 A (70 kW), the capacitor 86 provides a 25 A current to the vehicle electronic loads 44. The capacitors 76, 86 have the same voltage of 350V. The switches 50-56 show 400V voltage stress and the switches 68-74 and 78-84 have 350V voltage stress.
The traction battery 40 has a discharge current of 172.5 A (138 kW) for the motor drives 42 and vehicle loads 44. Even though the capacitor 86 provides a 25 A current to the vehicle electronic loads 44, the capacitors 76, 86 have the same voltage of 400V under the voltage balance control shown in
The voltage of the capacitor 58 is controlled to 400V. The traction battery 40 has a discharge current of 62.4 A for the vehicle loads 44 and vehicle to grid or on-board generating operation. Even though the capacitor 86 provides a 25 A current to the vehicle electronic loads 44, the capacitors 76, 86 have the same voltage of 400V under the voltage balance control. The voltage stresses are also shown.
The algorithms, methods, or processes disclosed herein can be deliverable to or implemented by a computer, controller, or processing device, which can include any dedicated electronic control unit or programmable electronic control unit. Similarly, the algorithms, methods, or processes can be stored as data and instructions executable by a computer or controller in many forms including, but not limited to, information permanently stored on non-writable storage media such as read only memory devices and information alterably stored on writeable storage media such as compact discs, random access memory devices, or other magnetic and optical media. The algorithms, methods, or processes can also be implemented in software executable objects. Alternatively, the algorithms, methods, or processes can be embodied in whole or in part using suitable hardware components, such as application specific integrated circuits, field-programmable gate arrays, state machines, or other hardware components or devices, or a combination of firmware, hardware, and software components.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. The words processor and processors may be interchanged herein, as may the words controller and controllers.
As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes may include, but are not limited to strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, embodiments described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3950691 | Ohba | Apr 1976 | A |
| 6737756 | Gale | May 2004 | B1 |
| 6930404 | Gale et al. | Aug 2005 | B1 |
| 7719138 | Gallegos-Lopez | May 2010 | B2 |
| 20090168461 | Nakahori | Jul 2009 | A1 |
| 20210191892 | Yu | Jun 2021 | A1 |
| 20220161673 | Jimenez Pino | May 2022 | A1 |
| Number | Date | Country |
|---|---|---|
| 102010001243 | Jul 2011 | DE |
