Active ripple energy storage circuit via standalone amplifier module connected to a high-voltage DC bus

Abstract

A motor vehicle power system includes a battery power control module including a bidirectional power factor correction circuit and an isolated DC / DC converter connected between a bus and the bidirectional power factor correction circuit. The system further includes a traction battery connected to the bus and a boost module including a capacitor connected between the battery power control module and the traction battery.

Description

FIELD OF TECHNOLOGYThis disclosure relates to automotive power systems.GENERAL STATE OF THE ARTA motor vehicle may use electrical energy from a traction battery to power an electric machine. The electric machine may convert this electrical energy to mechanical energy to propel the vehicle. The motor vehicle may include various power electronics equipment to condition and store electrical energy.SUMMARYA vehicle has a power system that includes a traction battery, a battery current control module, an amplifier module, and a bus that electrically connects the traction battery, the battery current control module, and the amplifier module. The vehicle also includes a controller that, while the battery current control module is supplying AC current from an AC source to the bus, operates the boost module to alternately store energy from the bus and discharge energy to the bus such that the traction battery receives DC current from the bus.A method includes, while a battery current control module outputs AC current from an AC source to a bus, operating an amplifier module such that a capacitor thereof alternately stores energy from the bus and discharges energy to the bus, causing a traction battery to receive DC current from the bus.An automotive power system includes a bus, a battery current control module including a bidirectional power factor correction circuit and an isolated DC / DC converter coupled between the bus and the bidirectional power factor correction circuit and switchable to an AC source, a traction battery coupled to the bus, and an amplifier module including a capacitor coupled to the bus between the battery current control module and the traction battery and switchable to a DC charge source.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a schematic diagram of a battery current control module circuit with active ripple energy storage circuit added. FIG. 2 is a schematic diagram of an amplification circuit that charges an 800 V traction battery from a 400 V DC fast charging station. FIG. 3 is a block diagram of a high voltage charging architecture of an electric vehicle configured to charge a traction battery using power from an AC grid, a 400V DC fast charging station, and an 800V DC fast charging station. FIGS. 4A, 4B, 4C, and 4D show typical waveforms for AC line voltage, battery current control module current, boost current, and traction battery current, respectively.DETAILED DESCRIPTIONEmbodiments 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 respect to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not expressly illustrated or described. The illustrated combinations of 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.Battery current control modules (BCCMs) play a role in managing the flow of electric current to and from the traction battery. BCMs function as controllers that interface between the traction battery, the charging system, and the electrical loads. They monitor and control various parameters such as the state of charge, voltage, and temperature of the battery, and manage the flow of current to the traction battery based on this information. BCCMs may facilitate charge control by supervising the charging process of the traction battery and managing the voltage and current supplied by the charging system. By monitoring the state of charge of the traction battery and adjusting the charging parameters accordingly, BCCMs attempt to ensure that the traction battery receives the appropriate level of charge to maintain performance. Likewise, BCCMs may be responsible for discharge control. They may manage the current output by the traction battery to the electrical loads in the vehicle. By controlling the current flow, BCCMs may ensure a controlled supply of power to the various electrical components and systems. BCCMs may also implement various measures for the traction battery. For example, they may monitor the battery temperature to prevent overheating. They can also detect overvoltage or undervoltage situations and implement measures to exclude short circuits or excessive current consumption. BCCMs may have diagnostic capabilities. These modules may monitor the state and performance of the battery system. They can log codes and provide diagnostic information, which facilitates maintenance.Communication interfaces are often included in BCCMs. These interfaces, such as a controller area network (CAN) or local interconnect network (LIN), allow BCCMs to exchange information with other vehicle systems that include the engine control unit or the body control module. This allows coordinated operation and integrated control across various vehicle functions. BCCMs may receive commands or instructions from other controllers and adjust current flow accordingly.The electrolytic capacitor bank is considered one of the large components in the BCCM. It can consume almost 20% of the total BCCM housing volume. To help increase the power density of the BCCM, an active ripple energy storage circuit may be added, which may reduce the overall size of the electrolytic capacitor bank by up to 70% estimated.Referring to FIG. 1, an on-board charger circuit topology 10 includes an electromagnetic interference filter 12, a bidirectional power factor correction circuit 14 (e.g., a one / three phase bidirectional totem pole power factor correction circuit), an active ripple energy storage circuit 16, and an isolated high voltage DC / DC converter 18. The active ripple energy storage circuit 16 is connected between the bidirectional power factor correction circuit 14 and the high voltage isolated DC / DC converter 18. The high voltage insulated DC / DC converter 18 is connected between the active ripple energy storage circuit 16 and a traction battery 20. The topology 10 is connected to an AC source 22 via the electromagnetic interference filter 12. Power from the AC source 22 may thus charge the traction battery 20.Components associated with the active ripple energy storage circuit 16 may introduce certain problems. The reduction in package size associated with incorporating the active ripple energy storage circuit 16 may not be sufficient to warrant the introduction of these certain problems. Here, an amplifier module is proposed to perform the function of the active ripple energy storage circuit 16.Referring to FIG. 2, an amplifier circuit topology 24 includes an electromagnetic interference filter 26 and an amplifier circuit 28. The topology 24 is connected to a 400 V DC fast charge source 32 via the electromagnetic interference filter 26. Power from the 400V DC fast charge source 32 may thus charge the traction battery 20.As mentioned above, an implementation of an active ripple energy storage circuit using an amplifier module mounted on a DC bus is proposed. Referring to FIG. 3, a vehicle 34 includes the topology 10', the traction battery 20, the topology 24, a high voltage bus 34, and a controller 36. the topology 10' is the topology 10 with the active ripple energy storage circuit 16 omitted and the bidirectional power factor correction circuit 14 connected directly to the isolated high voltage DC / DC converter 18. The topologies 10', 24 are connected to the traction battery 20 via the high-voltage bus 34. The controller 36 is in communication with and / or exercises control over the components of FIG. 3.The AC source 22 can be connected to the topology 10' via the electromagnetic interference filter. The 400 V DC fast charge source 32 is switchable to the topology 24 via the electromagnetic interference filter 26. An 800V DC fast charging station 38 is connectable to the high voltage bus 34.In a typical implementation, the on-board boost circuit is not utilized while the traction battery is charged via the AC grid. This is not the case here. The topology 24 is used to implement the energy storage function. When the traction battery 20 is charged from the AC source 22, the input of the boost module 24 would be disconnected from the 400V DC fast charging station 32 and unloaded. The high voltage DC bus 34 would also be disconnected from the 800V fast charge DC station 38. The amplifier module 24 is controlled via the controller 36 to store energy and discharge energy into its input capacitor C 1. Capacitor C 1 is expected to experience a ripple voltage that is proportional to the power output to traction battery 20. The current generated by the amplifier module 24 is synchronized to the AC line voltage from the AC source 22. The amplifier module 24 is controlled via the controller 36 to generate an AC current proportional to and synchronized with the AC current generated by the BCCM 10'. The AC current of the boost module is controlled via the controller 36 to minimize the ripple current delivered to the traction battery 20. The current generated by the amplifier module 24 has an average value of zero.The bidirectional power factor correction circuit 14 converts AC to DC, synchronizing input current to AC voltage for a power factor of one. It produces DC with a low frequency ripple, excluding active ripple energy storage and only using output capacitors for filtering purposes, not for energy storage. The output current of the BCCM converter varies directly with the AC voltage, thereby ensuring instantaneous power matching between the AC input and the DC output. This converter charges the traction battery 20 with a current that mirrors the AC voltage that drops to zero when the AC input does so. Meanwhile, the amplifier circuit 28 adjusts the voltage across the capacitor C 1 to produce an AC current, adjusting the output of the BCCM to be very similar to a DC current for the traction battery 20, and managing low frequency ripple according to the magnitude and voltage of the C 1. The amplifier circuit 28 is configured for bi-directional power and is capable of passing excess current from the BCCM 10' back to the C1 and vice versa to ensure continuous battery charging with minimal ripple. It controls the voltage of the C1 within a predefined range. By utilizing the lower switch (e.g., metal-oxide-semiconductor field effect transistor) as the active switch and the upper switch (e.g., metal-oxide-semiconductor field effect transistor) as the synchronous rectifier, the circuit 28 functions similar to a boost converter, effectively increasing the voltage from the C 1 to the level required by the traction battery 20.Referring to FIGS. 4A, 4B, 4C, and 4D, the BCCM 10' in this example does not include an energy storage element. Therefore, its output current is proportional to the instantaneous power of the AC grid. This means that when the AC line voltage is zero, the output current of the BCCM 10' is zero. The amplifier module 24 is operated to absorb the ripple current by charging and discharging its input capacitor C 1. Thus, the net current delivered to the traction battery 20 is DC.It is also possible to add a small energy storage capacitor in the BCCM 10' so that the BCCM output current does not drop to zero during the zero crossing of the AC line voltage. This reduces the load on the amplifier module 24: the average energy stored in the capacitor C 1 in an AC conduction cycle is reduced.The BCCM module 10' is configured to operate normally even when the amplifier module 24 is inoperative. The boost module 24 aims to reduce the low frequency ripple provided to the traction battery 20 while charging from the AC source 22.Because the amplifier module 24 is implemented as a separate module, communication between the BCCM 10' and the amplifier module 24 may be established in various ways. The BCCM 10' may send line voltage, frequency and phase information to the amplifier module 24. A controller in the boost module 24 derives the reference current that minimizes the low frequency ripple seen at the traction battery 20 for a given charging current in a known manner. The BCCM 10' may produce an analog or digital signal for the reference current that is fed to the amplifier controller. The BCCM 10' may communicate reference current signals to the amplifier module 24 via digital communication methods such as CAN, LIN, I2C, Ethernet, etc., as proposed above.The algorithms, methods, or processes disclosed herein may be executable or implemented by a computer, controller, or processing device, which may include any dedicated electronic control unit or programmable electronic control unit. Additionally, the algorithms, methods, or processes may be stored in many forms as computer or controller executable data and instructions including, without limitation, 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 may also be implemented in software executable objects. Alternatively, the algorithms, methods, or processes may be implemented 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. For example, a vehicle may not include a port configured to receive charge from an 800 V DC fast charging station. Other BCCM and amplifier module architectures are also contemplated, etc.The terms 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 these disclosed subject matters. The terms "controller" and "controllers" may be used interchangeably herein, for example, because the functionality of a controller may be distributed across multiple controllers / modules that include battery current control modules and amplifier modules, all of which may communicate via the techniques described above.As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be expressly described or illustrated. While various embodiments could have been described as providing 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 will understand that one / 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, building, size, serviceability, weight, mullability, ease of assembly, etc. Thus, 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.According to the present invention, there is provided a vehicle comprising: a power system including a traction battery, a battery current control module, an amplifier module, and a bus electrically connecting the traction battery, the battery current control module, and the amplifier module; and a controller programmed to, while the battery current control module is delivering AC current from an AC source to the bus, operate the amplifier module to alternately store energy from the bus and discharge energy to the bus such that the traction battery receives DC current from the bus.According to one embodiment, the AC current is proportional to a current power of the AC source such that when a voltage of the AC source has a value of zero, the AC current has a value of zero.According to an embodiment, current associated with an operation of the amplifier module has an average value of zero.According to an embodiment, the battery current control module is configured to communicate information related to the AC source to the amplifier module.According to one embodiment, the battery current control module includes a bidirectional power factor correction circuit and an isolated DC / DC converter.According to one embodiment, the bidirectional power factor correction circuit is a bidirectional totem pole power factor correction circuit.According to an embodiment, the isolated DC / DC converter includes a transformer, a jumper, and a switch bank connected between the transformer and the jumper.According to the present invention, a method includes: while a battery current control module is supplying AC current from an AC source to a bus, operating an amplifier module such that a capacitor thereof alternately stores energy from the bus and discharges energy to the bus, causing a traction battery to receive DC current from the bus.In one aspect of the invention, the AC current is proportional to a current power of the AC source such that when a voltage of the AC source has a value of zero, the AC current has a value of zero.In one aspect of the invention, current associated with the operating has an average value of zero.In one aspect of the invention, the method includes communicating information related to the AC source to the amplifier module.According to the present invention, there is provided an automotive power system comprising: a bus; a battery current control module including a bidirectional power factor correction circuit and an isolated DC / DC converter connected between the bus and the bidirectional power factor correction circuit and configured to be connected to an AC source; a traction battery connected to the bus; and an amplifier module including a capacitor connected between the battery current control module and the traction battery to the bus and configured to be connected to a DC charge source.According to an embodiment, the invention is further characterized by a controller programmed to, while the battery current control module is supplying AC current from the AC source to the bus, operate the amplifier module to alternately store energy from the bus in the capacitor and discharge energy from the capacitor to the bus such that the traction battery receives DC current from the bus.According to one embodiment, the AC current is proportional to a current power of the AC source such that when a voltage of the AC source has a value of zero, the AC current has a value of zero.According to an embodiment, current associated with an operation of the amplifier module has an average value of zero.According to an embodiment, the battery current control module is configured to communicate information related to the AC source to the amplifier module.According to an embodiment, the isolated DC / DC converter includes a transformer, a jumper, and a switch bank connected between the transformer and the jumper.

Claims

A vehicle, comprising: a power system including a traction battery, a battery current control module, an amplifier module, and a bus electrically connecting the traction battery, the battery current control module, and the amplifier module; and a controller programmed to, while the battery current control module is supplying AC current from an AC source to the bus, operate the amplifier module to alternately store energy from the bus and discharge energy to the bus such that the traction battery receives DC current from the bus.The vehicle of claim 1, wherein the AC current is proportional to a current power of the AC source such that when a voltage of the AC source has a value of zero, the AC current has a value of zero.The vehicle of claim 1, wherein current associated with operation of the amplifier module has an average value of zero.The vehicle of claim 1, wherein the battery current control module is configured to communicate information related to the AC source to the amplifier module.The vehicle of claim 1, wherein the battery current control module includes a bidirectional power factor correction circuit and an isolated DC / DC converter.The vehicle of claim 5, wherein the bidirectional power factor correction circuit is a bidirectional totem pole power factor correction circuit.The vehicle of claim 5, wherein the isolated DC / DC converter includes a transformer, a jumper, and a switch bank connected between the transformer and the jumper.A method comprising: while a battery current control module is supplying AC current from an AC source to a bus, operating an amplifier module such that a capacitor thereof alternately stores energy from the bus and discharges energy to the bus, causing a traction battery to receive DC current from the bus.The method of claim 8, wherein the AC current is proportional to a current power of the AC source such that when a voltage of the AC source has a value of zero, the AC current has a value of zero.The method of claim 8, wherein current associated with the operating has an average value of zero.The method of claim 8, further comprising communicating information related to the AC source to the amplifier module.An automotive power system, comprising: a bus; a battery current control module including a bidirectional power factor correction circuit and an isolated DC / DC converter coupled between the bus and the bidirectional power factor correction circuit and configured to be coupled to an AC source; a traction battery coupled to the bus; and an amplifier module including a capacitor coupled between the battery current control module and the traction battery to the bus and configured to be coupled to a DC charge source.The automotive power system of claim 12, further comprising a controller programmed to, while the battery current control module is supplying AC current from the AC source to the bus, operate the amplifier module to alternately store energy from the bus in the capacitor and discharge energy from the capacitor to the bus such that the traction battery receives DC current from the bus.The automotive power system of claim 13, wherein the AC current is proportional to a current power of the AC source such that when a voltage of the AC source has a value of zero, the AC current has a value of zero.The automotive power system of claim 12, wherein current associated with operation of the amplifier module has an average value of zero.

Images